1

THE GUIDED TOOL FOR

OVERVIEW & MAINTANENCES

OF CENTRALISED AIR

CONDITIONING SYSTEM

2

INDEX

1. Introduction to Air conditioning systems

2. Chiller plant room a. Chilled water central air conditioning systems

b. Chilled central air conditioners

c. Water pumps

3. Cooling tower

4. Air Handling Units

5. Grills low side

APPENDIX Conclusion

3

CHAPTER 1

INTRODUCTION TO AIR CONDITIONING SYSTEMS

4

INTRODUCTION TO AIR CONDITIONING SYSTEMS

Air conditioning is a combined process that performs many functions simultaneously. It

conditions the air, transports it, and introduces it to the conditioned space. It provides heating

and cooling from its central plant or rooftop units. It also controls and maintains the

temperature, humidity, air movement, air cleanliness, sound level, and pressure differential in a

space within predetermined limits for the comfort and health of the occupants of the

conditioned space or for the purpose of product processing.

The term HVAC&R is an abbreviation of heating, ventilating, air conditioning, and refrigerating.

The combination of processes in this commonly adopted term is equivalent to the current

definition of air conditioning. Because all these individual component processes were

developed prior to the more complete concept of air conditioning, the term HVAC&R is often

used by the industry.

AIR CONDITIONING

An air conditioning, or HVAC&R, system is composed of components and equipment arranged

in sequence to condition the air, to transport it to the conditioned space, and to control the

indoor environmental parameters of a specific space within required limits.

Most air conditioning systems perform the following functions:

1. Provide the cooling and heating energy required

2. Condition the supply air, that is, heat or cool, humidify or dehumidify, clean and purify, and

Attenuate any objectionable noise produced by the HVAC&R equipment

3. Distribute the conditioned air, containing sufficient outdoor air, to the conditioned space

4. Control and maintain the indoor environmental parameters such as temperature, humidity,

Cleanliness, air movement, sound level, and pressure differential between the conditioned

space and surroundings within predetermined limits

Parameters such as the size and the occupancy of the conditioned space, the indoor

environmental parameters to be controlled, the quality and the effectiveness of control, and

the cost involved determine the various types and arrangements of components used to

provide appropriate characteristics.

Air conditioning systems can be classified according to their applications as

(1) Comfort air Conditioning systems

(2) Process air conditioning systems.

5

Assembly diagram:

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6

Energy Wheel: The energy wheel turns and absorbs the heat and moisture from the outdoor air

that comes into the AHU through the duct which supplies the outside air to the building. The

exhaust air (cooler and partly conditioned) which has to leave the building is first made to pass

through the energy recovery wheel. The moisture and heat absorbed by the energy recovery

wheel from the outdoor air from II is absorbed by the exhaust air which is cooler and partly

conditioned, thereby lowering the humidity and temperature of the outdoor air which is to be

passed over the cooling coils and then to conditioned space. Basically, an energy recovery

wheel utilizes the partially conditioned exhaust air leaving the building to condition the

incoming outside air. Other benefits of energy recovery wheels include removing moisture

from outdoor air which reduces or prevents moisture and humidity problems and it will also

reduce mechanical cooling in the summer.

An air system is sometimes called the air-handling system. The function of an air system is to Condition, to transport, to distribute the conditioned, recirculating, outdoor, and exhaust air, and to control the indoor environment according to requirements. The major components of an air system are the air-handling units, supply/return ductwork, fan-powered boxes, space diffusion devices, and exhaust systems. An air-handling unit (AHU) usually consists of supply fan(s), filter(s), a cooling coil, a heating coil, a mixing box, and other accessories. It is the primary equipment of the air system. An AHU conditions the outdoor/ recirculating air, supplies the conditioned air to the conditioned space, and extracts the returned air from the space through ductwork and space diffusion devices. A fan-powered variable-air-volume (VAV) box, often abbreviated as fan-powered box, employs a small fan with or without a heating coil. It draws the return air from the ceiling plenum, mixes it with the conditioned air from the air-handling unit, and supplies the mixture to the conditioned space. Space diffusion devices include slot diffusers mounted in the suspended ceiling; their purpose is to distribute the conditioned air evenly over the entire space according to requirements. The return air enters the ceiling plenum through many scattered return slots. Exhaust systems have exhaust fan(s) and ductwork to exhaust air from the lavatories, mechanical rooms, and electrical rooms. For study purpose we have taken the HVAC system of a large commercial building in a city like Bangalore , India, which operates , water cooled operation of 3 nos 800 TR chillers, 3 nos 800 TR cooling tower and 25 nos of AHU’S which caters the need of 300 odd tenats and common areas. The details are presented in the subsequent chapters below. We start with common problems faced by maintenance personnel. Issues in HVAC System –Observation queries raised by Facility team

Surging problems: Whenever all 3 chillers are running there is a surge problem and chiller trips automatically and unable to avoid it.

Maintaining condenser approach and range up to 4-5 is practically difficult.

Cooling tower capacity to be analysed on its position and capacities. Its present efficiency.

7

Whether we can maintain the water hardness less than 200 ppm and TDS less than 1500 ppm as per chiller standards after using the chemicals (anti scalant, Biocides).

The condenser water flow rate (using ultrasonic flow meter), condenser pressure are adequate or not.

Condition of fills in the cooling tower are good or not ?

Whether with the present load status can the plant run one sequence chiller-cooling tower- condenser pump.

Commenting on overall healthiness of the cooling tower, its fan condition and all other parameters. If conditions of occupancy not met

If designed parameter of chilled water and flow rate is supplied properly by Developer to the tenant Ceiling mounted /Floor mounted AHU the scope would end since the Internal CSU unit is self-supplied by end user/ tenant.

Hence its essential shop wise analyze the problem where ever issues are raised whether the CSU units are selected for adequate TR and appropriate coil sizing and thermostats of two way valves functional etc. needs to be conducted case wise when issues are raised.

Above false ceiling sealing to be cross checked for any mixing of zones above false ceiling etc. General Observation

Thermometers reading across the chiller and the chiller inbuilt sensors both are showing

different temperatures. Both needs to be checked for accuracy and the faulty set to be calibrated.

8

CHAPTER 2

CHILLER PLANT ROOM

9

CHILLER PLANT ROOM

A. Chilled Water Central Air Conditioning Plants

The chilled water types of central air conditioning plants are installed in the place where whole large buildings, shopping mall, airport, hotel etc., comprising of several floors are to be air conditioned. The plant room comprises of chiller units placed on civil foundations, primary, secondary pumps for pumping water from and to the AHU’s respectively positioned in different floors and condenser pumps for pumping water to and from cooling tower

In chilled water plants, the ordinary water or brine solution is chilled to very low temperatures of about 6 to 8 degree Celsius by the refrigeration plant. This chilled water is pumped to various floors of the building and its different parts. In each of these parts the air handling units are installed, which comprise of the cooling coil, blower and the ducts. The chilled water flows through the cooling coil. The blower absorbs return air from the air conditioned rooms that are to be cooled via the ducts. This air passes over the cooling coil and gets cooled and is then passed to the air conditioned space.

Chilled Central Air Conditioners Various Parts of the Chilled Water Air Conditioning Plant

Chiller is the heart of HVAC system. As the name indicates it is the machine which chills water and gives this chilled water further to units on low side. Chiller employs a gas usually termed as refrigerant that is passed through various components, finally exchanges heat to the medium (water or glycol) which carries this chillness to AHU, for cooling purpose or the equipment where process chilled water is required.

Chiller is classified as water cooled or air cooled. Generally Air cooled chillers are available for lower capacities (<500 TR). Air cooled chillers is devoid of cooling towers as the fans are part of condenser unit itself. Air cooled units are used wherever capacities are less and where there is a space constraint. Water cooled chillers on other hand are chillers of larger capacities (>500 TR) and which employs another unit called “cooling tower”. Individual standalone water cooled chillers are available up to 5000TR. The size of chiller is based on its capacity or tonnage (TR). 1 ton is defined as the amount of heat required to bring down temperature of water by 1°C. A 100TR chiller has a 100 times capacity to bring down the temperature of water. Similarly an 800ton chiller has capacity 800 times to bring down the temperature of water.

10

Chiller schematic:

11

12

Chiller description: A chiller comprises basically of 4 components.

Compressor: A compressor compresses the refrigerant and pushes it to the condenser. The compressor is classified depending on type of compression. Generally different compressors are screw type, centrifugal type, scroll type, reciprocation type etc.

Screw type utilizes screw elements to compress the gas. The gas is allowed to pass through the screw profile, which is rotating on a common rotor and gas progresses it get compressed.

Reciprocation type uses a piston cylinder arrangement. The piston pushes the gas and compresses it.

Centrifugal type uses a backward current impeller on a rotor. As the refrigerant passes through the impeller its pressure increases and gets pushed forward to the condenser.

Scroll type, as the refrigerant gets compressed, its pressure and temperature increases before entering the condenser.

Condenser: condenser is the section of chiller where gaseous foam condensation takes place. The high temperature refrigerant gets condensed and becomes liquid phase at the end of condensation. The condenser usually consists of tube made of cu, where water passes through it and gas flows on the opposite direction around its periphery. The mode of heat exchange is convection where there is no physical contact and as the refrigerant and water traverses through opposite direction the refrigerant

13

gradually becomes cool and condensed, water eventually gains heat. The pressure of refrigerant is maintained constant. The operating pressure is between 720-780 KPA for an 800TR chiller. Expansion valve: It’s a float value where there is pressure drop of the refrigerant. The pressure drops and the refrigerant regains its gaseous form. Evaporator: The refrigerant travels through a shell and water returning from AHU travels through the tube. Here too there is a heat exchange between the refrigerants and water. The water which is at high temperature say 14°C up to 7°C gets pumped back to AHU. The PH scale diagram of a chiller is given below indicating flow of refrigerant.

12 compression stage 23 condensation stage 34 Expansion stage 41 Evaporation stage Refrigerents commonly called as gas used in chillers:

1) CFC’s (chloro flouro carbons) R11, R12, R13,R14, R15 etc

2) HCFC’s (Hydro chloro flouro carbons) R22, R123, R124, R141b, R142b

3) HFC’s (Hydro flouro carbons) R32, R123, R134a, R143a, R142b

In modern day chillers HCFC’s are most commonly used refrigerant as the have ODP (Ozone depletion potential) very minimal or zero. These refrigerants even in case of leak, escape to surroundings may not cause depletion of ozone and protects it.

Let us take an example of a 800 TR chiller of a xxxx Brand make with all specs given below

1

2

3

4

14

CHILLER Calculations:

IKW =

Motor KW = V=voltage of 3 , I=Amps, Cos = power factor Tonnage (TR) = ( ) IKW of chiller = 449/800=0.56

System IKW of 800TR chiller: Based on formulas mentioned above, the IKW of chillers are calculated. Example below is the tabulated record of a real time 800 TR chiller which is operational in a large commercial building.

15

Chiller#1

Chiller#2

TIME Delta T( 'F) Tons

%

Efficiency Volts(V)

Load (

Amps) PF Motor KW IKW

% OF

COOLING

CAPACITY

KWH

consumption

9:00:00

10:00:00

11:00:00

12:00:00 9.9 747.45 93.43125 392.4 691.9 0.9 244.3514 0.3269134 95.36 407.8

13:00:00 9.9 747.45 93.43125 396.7 690 0.9 246.3507 0.3295882 94.5 397

14:00:00 9.18 693.09 86.63625 401.4 626.5 0.9 226.32939 0.3265512 86.5 440

15:00:00 9.54 720.27 90.03375 402 646 0.9 233.7228 0.3244933 89.1 401

16:00:00 9.54 720.27 90.03375 401 646 0.9 233.1414 0.3236861 91.8 406

17:00:00 9.36 706.68 88.335 397.9 661.9 0.9 237.03301 0.3354177 91.2 504

18:00:00 9.9 747.45 93.43125 395.7 691.9 0.9 246.40635 0.3296626 95 347

19:00:00 10.08 761.04 95.13 403.5 686.2 0.9 249.19353 0.3274382 94.3 438

20:00:00 9.54 720.27 90.03375 400.8 654 0.9 235.91088 0.3275312 91.2 448

21:00:00 9.9 747.45 93.43125 400 661.4 0.9 238.104 0.3185551 92.9 355

22:00:00 11.52 869.76 108.72 404 688.1 0.9 250.19316 0.2876577 95.8 282

23:00:00 8.5 641.75 80.21875 405 538.1 0.9 196.13745 0.3056291 74.8 511

4936.8

TIME

Delta T ( 'F) Tons

Efficiency

of

Tonnage (

%)

Volt (V) I (Amps) PF Motor KW IKW % OF

COOLING

CAPACITY

CHILLER kW from

Conserv Meter

9:00:00

10:00:00

11:00:00

12:00:00 11.34 791.91 98.98875 401 695.6 0.9 251.04204 0.3170083 95.6

13:00:00 11.16 779.34 97.4175 402 688.1 0.9 248.95458 0.3194428 95.6

14:00:00 10.62 741.63 92.70375 400 658 0.9 236.88 0.3194046 89.1

15:00:00 10.48 731.85333 91.481667 398 611 0.9 218.8602 0.2990493 83

16:00:00 9.54 666.21 83.27625 399 583 0.9 209.3553 0.3142482 80

17:00:00 9.72 678.78 84.8475 401 598 0.9 215.8182 0.3179501 83.9

18:00:00 9.72 678.78 84.8475 396 596 0.9 212.4144 0.3129356 81.4

19:00:00 10.08 703.92 87.99 396 609 0.9 217.0476 0.3083413 86.2

20:00:00 10.3 719.28333 89.910417 396 609 0.9 217.0476 0.3017554 83.9

21:00:00 11.7 817.05 102.13125 399 678.1 0.9 243.50571 0.2980304 93.2 200.1

22:00:00 10.26 716.49 89.56125 400 599.1 0.9 215.676 0.3010175 82.1 266

23:00:00 6.84 477.66 59.7075 399 421.9 0.9 151.50429 0.3171802 58.5 119.8

585.9

16

Chiller#3

Chiller technical details : Let us take an example of 3 nos 800 TR capacity water

colled chillers of centrifuge type. Basically when the chiller is commissioned, data

sheet can be obtained by the manufacturer. This data will be in use and be

beneficial for operation and maintenaces of chillers. Every chiller will have a

unique serial no. Given below is a technical data of 800 TR chiller commissioned

and operational in a large commercial building in Bangalore.

Chiller Model xxxxxxxxx

Starter / VFD .. Starter - Unit Mounted, Wye-Delta Capacity ……………………………………………..………… 800 Tons Chiller Input Power …………………………………… 0.562 kW/Ton Refrigerant Type ……………………………………….. R-134a (Shipped Separately) Cooler Water box Type ................ Nozzle-in-Head, 150 psi Passes .... ………………………………………………………….. 2 Nozzle Arrangement …………………………………………. D Tubing .............. Super E2 (SUPE2), .025 in, Copper

TIME

TonsEfficiency

TR% OF

COOLING

CAPACITY

V (volts) I (Amps) PF Motor KW IKW

KWH

consumption

9:00:00 767.34 95.9175 95 395 693.8 0.9 246.6459 0.3214297 89.4

10:00:00 377.58 47.1975 58.3 397 421.9 0.9 150.74487 0.3992396 192.7

11:00:00 767.34 95.9175 97.4 399 705 0.9 253.1655 0.3299261 202.8

12:00:00 742.98 92.8725 96.9 392 699.4 0.9 246.74832 0.3321063 413

13:00:00 742.98 92.8725 96.6 389 695.6 0.9 243.52956 0.327774 348

14:00:00 718.62 89.8275 93.2 401 694.8 0.9 250.75332 0.3489373 543

15:00:00 682.08 85.26 83.6 402 609 0.9 220.3362 0.3230357 326.6

16:00:00 633.36 79.17 82.4 399 598.1 0.9 214.77771 0.3391084 516

17:00:00 633.36 79.17 82.1 396 601 0.9 214.1964 0.3381906 290.9

18:00:00 645.54 80.6925 83.6 399 603.6 0.9 216.75276 0.3357697 374.7

19:00:00 669.9 83.7375 88.1 396 594 0.9 211.7016 0.3160197 342.7

20:00:00 669.9 83.7375 86.5 397 622 0.9 222.2406 0.3317519 526.6

17

Entering Temperature ………………………………… 55.96F Leaving Temperature ……………………………. ... 44.00F Flow Rate …………………..………………………… 1600.0gpm Pressure Drop …………………………………………. 25.9ft/wg Fluid Type ……………………………………………….. Fresh Water Fouling Factor (hr-sqft-F)/BTU ................. 0.00010 Suction Temperature ………………………………….. 43.21F Compressor Map ID .......... ………………………………………………….. 21 Flow Fraction …………………………………………… 1.00 .... Head Fraction ………………………………………….. 0.97 .... Flow Controls Float Valve Size ……………………………………….. 8 ......... Flasc Orifice ........ ……………………………………………. 29 Control Paramters Surge/HGBP GVmin ………………………………….. 5% ..... Surge/HGBP Delta Tsmin .. ……………………………32.9F Surge Line Shape Factor …………………………….. -0.04 Surge/HGBP GVmax ……………………………………..100% Surge/HGBP Delta Tsmax …………………………… 56.37F Cooler Min DP . …………………………………………. 3.0psi Condenser Min DP ... ……………………………………… 2.2 psi Weights and Approximate Dimensions Total Rigging Weight …………………………………… 20684lb Total Operating Weight …………………………………24847lb Refrigerant Weight …………………………………….. 1430lb Length x Width x Height ..... 193.50 x 79.88 x 86.50 in Condenser Water box Type ………………………. Nozzle-in-Head, 150 psi Passes ....... ……………………………………………………….. 2 Nozzle Arrangement ………………………………………… S . Tubing Spike Fin III (SPK3), …………………………..025 in, Copper Entering Temperature ………………………………… 85.00F Leaving Temperature ………………………………….. 95.21F Flow Rate ……………………………………………….. 2184.0gpm Pressure Drop …………………………………………... 29.5ft wg Fluid Type ……………………………………………… Fresh Water Fouling Factor (hr-sqft-F)/BTU ……………………… 0.00025 Condensing Temperature ……………………………...98.18F Electrical Data (Starter per Z-415) Chiller Main Power Voltage/Hertz …………………….. 415-3-50 Oil Pump Voltage/Hertz ……………………………….. 400-3-50 Chiller Input Power ……………………………………… 0.562 kW/Ton Motor RLA ... ……………………………………….……….. 724 Motor OLTA …………………………………………....... 782 ...

18

Motor LRYA ……………………..……………………. ..... 1903 Motor LRDA ………………………………………. ......... 5524 Max Fuse/CB Amps ……………………………… ....... 1600 Min Circuit Ampacity …………………………….. ....... 909

Maintenance of chillers: Condenser approach going up: One of the most common practical applications is that condenser approach rising. This value can be viewed on the display of chillers. Usually the approach sensor is calibrated by Manufacturer and recommended by them to verify the data periodically Reason: Actually no predefined value for maintaining condenser approach. But most manufacturers recommend approach to be maintained as less as possible below 2° C even 1° C a patience value.

If approach is maintained constant then it is an indication is parameter is maintained well.

If approach shoots beyond 4.5°C then maintained constant, then water parameters are to be checked.

If continuous variation of approach/fluctuation above 4.5 °C then solution to bring down is cited below

Chiller surge problem/ tripping: Possible surge causes are: 1. Poor water flow in condenser. 2. Poor water flow in evaporator. 3. Scaled condenser. 4. Scaled evaporator. 5. Low refrigerant charge. 6. Combination of all above. 7. No condensable gas in refrigerant. 8. Bad refrigerant quality. Solution – Chiller manufacturer to survey the chillers and check condition and give report on

Condenser maintenance approach and range up to 4-5 Increased approach temperature between liquid refrigerant and leaving water indicates water-side fouling. With clean tubes, approach temperature will typically vary from 10F at 100% load to 1F at 10% load. This emphasizes the importance of duplicating the baseline load conditions when comparing approach temperatures. Ideally condenser approach should be minimal ( < 2 C). Over the period of time as the unit runs, approach degrees raises. For a well maintained chiller approaches should be <3 at peak load conditions and all times

19

A lower-than-expected approach temperature, accompanied by high condenser head pressure, high leaving condenser water temperature and higher-than-normal condenser water temperature differential indicate insufficient condenser water flow rate. A smaller condenser water temperature differential along with a high approach temperature. Solution: Check water parameters of condenser. The water parameter to be maintained within IS 3025 standards.

20

Recommended water quality is given below

But practically depending on water program for cooling tower, it is difficult to maintain all the parameters as cited above, also the recommendation of manufacture are far below than that general standard practices IS3025. But to maintain healthy water parameters for purposes of keeping approach within 4°C, it is recommended atleast to maintain water parameters atleast 10-15% as mentioned before. Still if problem persists Descaling of condenser is mandatory.

Mechanical Descaling of Condensor:

Chiller is to be taken for shutdown. Condenser inlet and outlet valves to be closed. If valves are not holding properly, dummy plates of condenser pipes to be fixed. Chemicals are used for Descaling. The most common descaling chemical is ASR-32 chemical. The chemical is mixed with water in a bucket and pumped into the condenser tubes till the water is emptied. All scale formation inside the tubes will come and out again next set of chemicals is poured into a tub mixed with water and recirculates again the end caps are open and brushed with mechanical brushes will Teflon bristles. The whole set of exercises of chemical circulation is done for 6-8 hours till most of the scales inside the condenser tubes are removed. The hard scales inside the tubes are thus dissolved and eventually removed off in the process.

Then the condenser valves to be opened and chiller to be switched on by ensure oil pressure is atleast 130 PSI. When chiller is running at its peak load based on the base demand set by the operator, the approach to be viewed and recorded. It is mandatory to view and record

21

approach on hourly basis and to ensure healthy maintenance practices is followed to keep up the approach at a constant desired level.

ASR chemical connection to condenser inlet Scale inside the condenser tube

22

Dummy insertion between condenser inlet and cooling tower Header

23

Checking for scales inside condenser tubes ASR chemicals used for descaling

Jet pump condenser cleaning

24

Tube brushing inside condenser tube

Teflon based brush used for Descaling Chemical recirculation

25

1. Since Oil pressure less than 120 psi when oil is heated to 50 C of chiller # 1 > 4.2, new oil filter to be replaced and gasket.

2. New expansion float valve for replacement

26

3. Removing the old float valve after chiller shutdown

4. Old float valve removed

27

5. Gasket and new float valve fixing

6. New float valve with gasket ready for fixing

28

7. New float valve fixed and nitrogen purging in progress

8. After vacuuming and achieving vacuum pressure ( 200 micron) the same gas filled back.

29

9. New oil filter fixed for chiller # 2 ( due to low oil pressure fault)

Evaporator Descaling : Similar to the above, if evaporator approach is above 2.5°, then tubes of evaporator has to be descaled similar in lines of condenser descaling. Evaporator approach >2.5 is a general indication of possibility of scale formation on evaporator tubes.

Chiller energy calculations: Based on all the data, the chiller energy consumption is calculated

and tabulated based on the data below for a real time 800 TR chiller

Chiller Energy Parameter Units Chiller

Chiller Tonnage Tons 800

Operation Hrs. hrs./day 14

Operation days days/year 365

Load % 96

Design Chiller efficiency Kw/Ton 0.56

Cost KW-hr LC/KW-hr 7.81

Condenser Approach Temp before cleaning ˚C/º F 7.00

Condenser Approach Temp after cleaning ˚C/º F 3.00

30

Increase in Condenser Approach Temp in one year ˚C/º F 4.00 (approach before-after)

1° increased in approach reduce chiller performance by 3% % 12.00( approach*3)

DESIGN ENERGY CONSUMPTION

@ Design Chiller Efficiency Kw/ton 0.56

*Total Energy Consumption LC/year 17,164,106

CURRENT ENERGY CONSUMPTION

**@ Actual Chiller efficiency Kw/ton 0.627

***Total Energy Consumption LC/year 19,223,798

*Total design energy consumption is a multiplied factor of chiller tonnage, operation hours, operation days, maximum load and design chiller efficiency and cost of KW/hr. **Actual chiller efficiency is added factor of design chiller efficiency and multiplied factor of 1° increase in approach reduce chiller performance by 3% of designed chiller efficiency. ***Total actual energy consumption is percentage of chiller tonnage, operation hours, operation days, load, design chiller efficiency, cost KW-hr. This data to be viewed and analyzed periodically to understand the chiller consumption and efficiency of chillers. The monthly and annual consumption of actual has been mentioned in appendix.

Automatic tube cleaning (ATC) system: Since descaling ensures a proper chemical is an expensive methodology, most of the areas where the approaches are on higher side and despite descaling there is no decline of approach degrees then ATC is recommended. This system utilizes a sponge ball which circulates inside the condenser tubes. The scaling gets attracted and trapped on the surface of the balls. After this the ball gets into the collector where it is washed and it is ready for next cleaning. Tube life is enhanced by preventing fouling.

31

Advantages of using ATC:

Online cleaning with no chiller downtime Fully automatic, effortless cleaning Maintains constant optimal performance Lowers average condenser temperature by 2°C-3°C Delivers 6%-12% operating cost saving

32

A. Water Pumps: The water system includes primary, secondary and condenser water pumps. The purpose of the water pump system is (1) Secondary pumps to transport chilled water from the evaporator to the air-handling units and primary pump transfers water back from AHU to evaporator of chiller plant Secondary pumps:

33

2) Condenser pump to transport the condenser water from the cooling tower to the condenser inside the chiller plant. After the condenser water has been cooled in the cooling tower, it flows back to the condenser of the centrifugal chillers. The temperature of the condenser water again rises owing to the absorption of the condensing heat from the refrigerant in the condenser. After that, the condenser water is pumped to the cooling towers by the condenser water pumps.

Condenser pump:

34

3) Primary Pumps: The chilled water is cooled in three centrifugal chillers and then is distributed to the cooling coils of various air-handling units located on individual floors. The temperature of the chilled water leaving the coil increases after absorbing heat from the airstream flowing over the coil. Chilled water is then returned to the centrifugal chillers for re-cooling through the chilled water pumps. Primary pumps:

35

Below mentioned is the pump specifications which has to be understood to check and maintain healthiness of pumps. In usual practices stand by pumps are available in case if any one of the pump fails. Generally load on pump terminals are checked and verified with the rated load. Speed can be checked with devices like ultrasonic Tachymeter, to understand the speed in which its running. Couplings are checked for damages, misalignment etc. Electrical motors are to be checked for winding etc.

HVAC Water pump specifications

36

CHAPTER 3

COOLING TOWER

37

COOLING TOWER

The cooling tower is used to cool the water that absorbs heat from the compressor and the condenser. When water flows through these components some water gets evaporated, to make up this loss some water is also added in the cooling tower. The cooling tower is of evaporative type. Here the water is cooled by the atmospheric air and is re-circulated through the compressor and the condenser.

Cooling towers are the primary component used to exhaust heat in open recirculating cooling systems. They are designed to maximize air and water contact to provide as much evaporation as possible. This is accomplished by maximizing the surface area of the water as it flows over and down through the tower structure. First, the water is distributed evenly across the top of

38

the cooling tower structure. Tower distributions decks can be a series of spray nozzles oriented up or down (like a landscaping sprinkler system) to uniformly distribute the water over the tower structure. In some cases, the distribution deck may just be a series of holes through which the water falls onto the tower structure. Regardless the distribution deck must uniformly apportion the recirculating water across the tower structure. Broken nozzles or plugged orifices will impede uniform distribution across the tower structure, negatively impacting the overall heat exchange capacity of the system. As the water falls from the distribution deck, the surface area is further expanded in the fill section. Older tower systems may feature splash bars made of plastic, fiberglass, or wood that serve to break the falling water into tiny droplets. In recent years, many different forms of labyrinth like packing or film fill have been incorporated. The closely packed nature of film fill causes the water to travel through this portion of the tower in thin streams, improving thermal efficiency and the evaporation rate, thereby increasing heat rejection. To minimize losses due to drift and help direct airflow into the tower, louvers and drift eliminators are commonly used. Louvers are most often seen along the sides of the tower structure, while drift eliminators reside in the top section of the tower to capture entrained water droplets that may otherwise leave through the stack. Damaged or incorrectly oriented louvers along with damaged drift eliminators will lead to excessive losses due to drift from the tower structure. Therefore, louvers and drift eliminator sections should be routinely inspected and repaired to ensure optimal water usage. After the water passes through the fill it cascades down to a collection basin at the base of the tower structure. From the basin the cold water can be pumped back into the system to extract process or comfort cooling needs and begin the cycle all over again. By design, cooling towers consume large volumes of water through the evaporation process to maintain comfort cooling or process cooling needs, although they use significantly less water than similar capacity once-through cooling systems. Because the evaporative loss is water containing little to no dissolved solids, the water remaining in the cooling tower becomes concentrated with dissolved solids, which can lead to scaling and corrosive conditions. To combat these problems, water with high total dissolved solid content must be drained from the system via “blow down.” The associated losses caused by blow down, evaporation, drift, and system leaks must be accounted for by system make-up requirements.

39

Cooling tower hood

Inlet from

condenser

Outlet to

condenser

40

Let us take an example of cooling tower of 800 TR of 3 no’s, equal to that of chillers as mentioned in the previous chapter. The technical data sheet has to be obtained from the manufacturer of Cooling towers and to be recorded and used by the maintenance personnel to calculate data and carry out maintenance activities. An actual technical data sheet of an operational cooling tower is mentioned below

TECHNICAL DATA SHEET OF COOLING TOWER Designed Duty Conditions: Hot Water Temperature : 95.00°F Cold Water Temperature : 85.00°F Wet Bulb Temperature : 78.00°F Water Flow Rate : 2400.00 USGPM Heat Rejection Capacity : 30,26,700 KCal/hr ( 12.04 x 106 BTU/hr) 1. Components classification no. : ID-2480F4C2 (With FRP Cowl for reducing the noise) 2. Type : Induced Draught Counter flow 3. Distribution : Gravity flow (static)/ Main header and branch arm system 4. Wet bulb approach : 7°F 5. Dimensions (mm) # Approx. : 7200 x 6000 x (3715 + 1500) 6. Operating wt. (kg) : 11200 7. Fill wetted area (sq.) : 6605 8. Evaporation loss : 1.00% 9. Drift loss : 0.05% 10. Total water loss : 1.05% (without bleed off) 11. Fan dia. (mm) : 1800 12. No. of fans : 4 (Two per cell) 13. Air flow (CFM) : 50,700 CFM per cell x 4 14. Tip velocity (m/min) : 3925 15. Fan material & Type : Cast Aluminum, Axial flow 16. Motor HP : 10 HPx 04 Nos. (Two per cell) RPM : 710 Type : Squirrel Cage (IP55), TEFC 17. Make : New India (NEI) 18. Tower structure and Basin : FIBREGLASS 19. Fills : High efficiency PVC 'Fills pack with UV stabilization

41

20. Drift Eliminators : PVC 21. Fill support : HOT DIPPED GALVANIZED FRAME 22. Bird screen : HOT DIPPED GALVANIZED FRAME 23. Distribution supports : HOT DIPPED GALVANIZED FRAME 24. Ladder : M.S.H.D.G. 25. Hardware : Electroplated

Maintenance of cooling tower: Cooling tower capacity & efficiency Rated Capacity of cooling tower is in same capacity of chiller, 800 TR . The data sheet from manufacturer and found the same to be in order It is observed that cooling towers are placed in a well installation, two sides there is blockage of air flow due to the Walls and only one side air entry was seen prominently. Position of cooling tower: Location of cooling tower matter a lot and this has to be taken care initially during the design/commissioning itself. Basically the following to be taken care in the nascent stage it to prevent further problems.

It should be positioned so that it is free on all 4 sides ( atleast 4 entries) It should be located at such a place so that no construction activity is going on the

vicinity. No dust accumulates or possibility of it to entering into cooling tower anywhere in the surrounding.

It should be noted that no foreign particles can enter the body during any strong winds etc.

The fan can extract air and there is no obstruction of heat rejection or nothing above fan.

No hot air/extract fans/exhaust fans given hot air near the vicinity of cooling tower else hot air will disturb the heat exchangers of water inside cooling tower ( CDW Δt).

If Cooling tower is surrounded by walls on 3 sides there is chance of Bypass of hot air with air intake Sizing of the cooling tower: Generally it is mandatory that the cooling tower tonnage is atleast 1.25 times higher than the chiller tonnage in order to get a good condenser inlet temperature, and maintaining good condenser pressure.

42

Whether with the present load status we can run one sequence chiller cooling tower condenser pump. With all notified observations one chiller –Cooling tower and one condenser pumps will fall inadequate due to below possible reasons:

• As notified cooling tower might not be working to fullest potential • As notified there might be chances of condenser scaling inside chiller • As notified flow rates might not be adequate as per improper condenser water

balancing • Across the De-coupler line if a flow meter is fixed we can observe the quantum of

bypass • Currently the Secondary pumps are running in Manual mode and @ fixed HZ. • Entire Pumping system has to be made automatic and set in Auto mode. • All Tenant ( retailers, office cabins etc) Chilled water valves to be cross checked for

Functionality as the backpressure should modulate VFD of the pump with DP sensor sensing the same and for potential benefits of Energy savings Condenser pressure: condenser pressure plays an important role in knowing the flow of refrigerant and water inside the condenser tubes, Usually in this 800TR machine, the approach condenser pressure is to be maintained within 750-850 KPA. If the condenser pressure is higher than 850KPA, there is a trouble indicating variation in Δt of condenser, higher cold water inlet temperature not performing its action of reducing water temperature to a set value. If the pressure rises up to 900KPA, the chiller automatically trips.

43

Water balancing reports:

The above mentioned water balancing report has been studied during the commissioning stage of the equipment’s. The balancing has been done by rotating the balancing valves at a particular pressure and locked at that stage for the flow and pressure to be constant at all points of time. Based on the above chart timely pressure can be checked using ultra sonic digital flow meter to analyze the flow. The flow can be taken to calculate the tonnage of chiller at any point of time, also the IKW factor of chiller. Condenser temperature (Δt): Condenser temperature difference is also an important factor of indicating the performance of the cooling tower. In usual practice the condenser Δt to be maintained less ≤ 4~5°C. The cold water inlet to be around 25°C (at humid cities like Bangalore) and cold water outlet to be not more than 30°C. If cold water inlet raises above 25°C and crosses 30°C then the chiller trips. This is a direct indication that cooling tower performance is decreased due to insufficient airflow and heat exchange between air and water. Cooling tower to be free on all sides so that the fan can extract maximum air from surroundings the thumb rule says all 4 meters to be free with no obstruction up to 4 from cooling tower body.

Control Ref LocationValve

Size

(mm)

Design

Flow

(GPM)

Design

Pressure

Drop at F/O

(bar)

Initial

measure

d drop at

F/O (bar)

Pressure

drop (bar) Flow (GPM)

% of

Design

Turns

Kv

Value

Chiller No 01 Plant Room 250 1600 0.02 0.14 0.36 1812 113 10.0 1015

Chiller No 02 Plant room 250 1600 0.02 0.14 0.1 1676 104.7 12.0 1211

Chiller No 03 Plant room 250 1600 0.02 0.14 0.09 1624 101.5 12.0 1211

Chiller No 01 Plant Room 300 2400 - 2519.6 - 2410 100.4 9.0 -

Chiller No 02 Plant room 300 2400 - 2186.3 - 1676 104.7 14.0 -

Chiller No 03 Plant room 300 2400 - 2608.6 - 1624 101.5 9.0 -

Cooling Tower - 01 Terrace 300 2400 - 1857.8 - 2385.3 99.4 14.0 -

Cooling Tower - 02 Terrace 300 2400 - 2738.2 - 2512 104.6 12.0 -

Cooling Tower - 03 Terrace 300 2400 - 2663.8 - 2420 100.8 11.0 -

Shaft 01, 01A & 02 Basement 250 1837 0.06 2328.4 0.29 1810 98 8 762

Shaft 01B Basement 150 630 0.03 764.56 0.43 633.78 100.6 8 219.8

Shaft 03 Basement 150 362 0.11 341.33 0.19 423.64 117 8 219.8

Shaft 04 Basement 200 1016 0.16 866.4 0.47 1013.5 99.7 6 335.1

Shaft 05 Basement 200 825 0.16 753.46 0.3 822 99.6 8 335.1

REMARKS : Water Balancing is done with 4 Nos Secondary pumps running @ 45 Hz

WATER FLOW READING- CONDENSOR

WATER BALANCING REPORT

WATER FLOW READINGS - CHILLER

Settings

FINAL READINGS

WATER FLOW READING- COOLING TOWER

44

Chemical Dozing in cooling tower: This is the most important aspect in any water cooled system, which employs cooling tower. Adequate quantity of chemicals are dozed in cooling tower basin of chemicals dozed in cooling tower basin to keep check on growth of bacteria/algae to control hardness TDS in turn which prevents scale formation to prevent growth of microorganisms in cooling tower body to maintain PH ( keep system in alkaline mode $ diminish acid contents) to prevent fouling. In any application the following chemicals are used

Biocides anti algae Bio nil Corrosion PH corrector Anti scalant reduce hardness

These chemicals are manually put into the dozing system. Whether maintaining the water hardness less than 200 ppm and TDS less than 1500 ppm as per chiller standards after using the chemicals (anti scalant, Biocides). Cooling tower Dosing needs to be fully atomized system. Mechanically maintaining cooling tower: Condenser water and makeup water parameters to be checked and monitored on daily basis. If abnormalities found then:

Recheck the chemical program of cooling tower Add shock absorbing chemical if required Manually shut down the cooling tower and remove the algae formation. Note before

algae form there will be slime formation, which is an indicator of further algae growth inside cooling tower.

Check FRC level in cooling tower. If chlorine level is nil then it is an ideal habitat for microorganisms to grow.

45

Cooling tower inlet and outlet sensors connected to BMS: It is ideal to connect the cooling tower parameters to integrated building management systems. It helps the maintenance personnel to check the ongoing parameters at all times. The values help in identifying the problems and help to diagnose the variances.

Condenser

water outlet

sensor

46

COOLING TOWER SYSTEM CALCULATIONS: To properly operate and maintain a cooling tower, there needs to be a basic understanding of the system water’s use. Water use of the cooling tower is the relationship between make-up, evaporation, and blow down rates. There are a couple simple mathematical relationships between the blow down rate, evaporation rate, make-up rate, and cycles of concentration of a cooling tower that are very useful to understand the principal flow rates. The first relationship illustrates the overall mass balance consideration around a given cooling tower:

1. Evaporation rate = ( )

Δt is degree centigrade which is the difference in cooling tower inlet and outlet temperatures

2. low down =

3. Cycles of Concentration =

4. Make-up = Let us consider below a cooling Tower, 3 nos of 800 TR capacity as per data sheet catering a large commercial building from the time it starts operation till it is closed.

Condenser

water inlet

sensor

47

COOLING TOWER CALCULATIONS:

The values are tabulated based on calculations using formulae above.

consumption in KL consumption in KL consumption in KL

Hrs Timings Cooling Tower # 1 Cooling Tower # 2 Cooling Tower # 3 Blow Down ( Bleed ) KL Cumulative

8:30 A.M

1 hr 9:30 A.M 3.1 3.1

10:00 A.M

2 hr 10:30 A.M 6.2 6.2

11:00 A.M

3 hr 11:30 A.M 9.3 9.3

12:00 P.M 3.1

4 hr 12:30 P.M 12.4 12.4

1:00 P.M 6.2

5 hr 1:30 P.M 15.5 15.5

2:00 P.M 9.3

6 hr 2:30 P.M 18.6 18.6

3:00 P.M 12.4

7 hr 3:30 P.M 21.7 21.7

4:00 P.M 15.5

8 hr 4:30 P.M 24.8 24.8

5:00 P.M 18.6 9.75

9 hr 5:30 P.M 27.9 27.9

6:00 P.M 21.7

10 hr 6:30 P.M 31 31

7:00 P.M 24.8

11 hr 7:30 P.M 34.1 34.1

8:00 P.M 27.9

12 hr 8:30 P.M 37.2 37.2

9:00 P.M 31

13 hr 9:30 P.M 40.3 40.3 32.55 32.5510:00 P.M

14 hr 10:30 P.M 43.4 43.4

14.5 hr 11:00 P.M 44.95 44.95 132.2

3.25

3.25

3.25

48

Total Time 14.5 hrs

a) Evaporation Rate =

Flow rate = 2500 GPM

considered from Flow meter

reading of M/s Carier

(1.8 x 5 x 2500)/1000

22.5

b) Blow Down (m3/hr) (Evaporation rate/COC)-1 COC=3 COC (Cycle of Concentration)

6.5 KL per hour

Actual blow down per day 30 min

c) Total water required /lost for blow down per

day3.25

KL (or m3)

d) Make up for Cooling Tower/day 45 m3 For 14.5 hrs

e)Total water required for 1 cooling tower for 1

day48.25 c) + d)

When 2 cooling Towers running

a) Total time 14.5 hrs 8:30 A.M to 11:00 P.M

b) Make up for 2 Cooling Tower 90 KL (or m3)

c)

Total water required /lost for blow down per

day3.25 KL (or m3)

d) Total water required for 2 cooling Towers 93.25 KL (or m3)

3rd Cooling Tower

a) Total Time 10.5 Hrs 11:00 A.M to 9:30 P.M

b) Evaporation Rate 22.5

c) Actual Blow down/day 30 min

d) Total water required/Lost in blow down 3.25 KL ( or m3)

e) Make up for 3rd cooling tower 32.59 KL ( or m3)

f) Total water required only for 3rd cooling tower 35.84 KL ( or m3)

Grand Total water required per day when all

cooling towers are running129.09 KL ( or m3)

The Make up water source is

the Raw water filtered through

WTP. ( RO water not

considered here).

When 1 Cooling Tower Running

8:30 A.M to 11:00 P.M

(1.8 X Delta T X Flow Rate of condensor)/1000

Cooling Tower Water Requirements

49

Blending ratios for water based on number of chillers in operation: In most of modern commercial buildings and cities where pure water is scarce, water from other sources like recycled water from STP with further treatment like reverse Osmosis/ultrafiltration is used. If recycled water is used for cooling tower make up’s then it is suggested to analyze the parameters as per water recommendation. Especially recycled water coming through RO will be more acidic, which is harmful to metal pipes and tubes. Further if TDS is below the recommended bandwidth then the water becomes incapable of heat exchanging. It is recommended to blend the recycled water with normal water on particular blending ratios as mentioned below. Basically these blending ratios if used will prevent corrosion of pipes and tubes and helps in longevity at the pipes. Water to be mixed depending on number of machines in operation is given below.

50

51

Quarterly a year cooling tower is to be taken for a shut down and following to be done

Remove all fills and physically observe for damage fills, deposit fills etc. Fills are to be changed once every two years.

After fills are removed water to be let in to check for functionality of all spray nozzles, if spray nozzles found to be chocked then it requires immediate replacement.

Check for drift eliminations if drift eliminate. If drift eliminations are faulty, it may effect heat dissipation Check at condenser basin for any rust formation. If rust forms at basin then there is a

possibility of it enters the condenser tubes and thereby gradually leading to deterioration of heat exchange capability.

Check for PVC header pipes of cooling tower. If pipe is blocked due to large deposits of scales foreign particles then end caps to be removed and thoroughly brushed and cleaned. This is again indicator of scaling, foreign particles entry into cooling tower.

The condition of fills across cooling towers

• It was observed the nozzles and spray is non-uniform and fins are damaged in the cooling tower.

• Cooling tower requires fin requirement and servicing to maintain the same properly • Cooling tower manufacturer can be called for Inspection and repairs and mend the same

For proper functionality. • AMC to be given for proper maintenance of cooling towers.

Shown below is a real time solution of changing fills of cooling tower and clearing all the blocks of distribution pipes.

52

1. Fills arrived and stored

2. Cooling tower Basin cleaning ( Manual)

53

3. Existing fills removed from cooling tower and checking the nozzles/splash cups

4. Removing the blockages from distribution pipes and checking all splash cups

54

5. Pipe block removal of cooling tower headers

6. Sample and condition of old fills removed from cooling tower

55

7. Algae content mass removed from cooling Tower

8. Manual cleaning and removal of all masses

56

9. Cleaned cooling tower basin after water wash

10. FRP coating with primer

57

11. FRP Coating on cooling tower Basin.

PROPERTIES OF WATER Water and its properties plays a very important role in the HVAC system. In fact it is the water which is used as medium for heat exchange inside condenser and heat exchange inside evaporator of chiller. Again water is transported into AHU from evaporator is used as a heat exchange medium with air, which makes air to be cooled and provided to area to be cooled.

CHILLER

C

on

den

ser

Ev

apo

rato

r

AHU

Water Water Water Outlet

Water inlet

58

Now this water which is essential in chiller as well as AHU should fulfill certain criteria in order to perform well in terms of heat exchange at the same time ensure it doesn’t have effect the tubes inside the chillers and AHU through which it traverses. The performance of water depends on the chemistry of water. The following parameters to be looked into

1) Hardness 2) TDS 3) Alkalinity 4) Chlorides 5) Silica 6) PH 7) Turbidity

PH: PH should be neutral. Neutral PH means it should be equal to or near the value 7. If PH<7, then it is acidic If ph>7, then it is basic It is always best to have PH 7 or even slightly greater but not less. Low PH indicates acidic and severely puncture the metals especially the copper tubes through which it traverses. It is better recommended for a maintenance practitioner to keep the PH value slightly basic up to 8.5 and operate the plant. Still higher values of PH may lead to gradual corrosion. PH can be boosted by adding PH booster like caustic soda in a correct proportion so that it is maintained below 8.5 at all times. Turbidity: It is the measure of suspended particles in water. Suspended particles can be in the form of smoke, dust and other foreign particles which may not be visible to the naked eye. Usually turbidity is higher in places wherever there are constructive mining activities going on nearby. Turbidity is measured in terms of NTU. Ideally turbidity should be within 5NTU as per IS3025 standards. TDS: TDS refer to the presence of compounds present in water, which contains carbon. The compounds can be solid compound, chemical compound or gaseous compound. Generally TDS is the presence of suspended minerals dissolved ions of suspended metals. These compounds are suspended in water and can’t pass through a filtration process. Generally it differs from TSS (total suspended solids) in which the suspended solids cannot pass through ≤2 micron filters. As per IS 3025 standards the TDS should be less than 500mg/liter. For HVAC applications TDS recommended in cooling tower makeup should be about 250PPM depending on program at condenser basin it can be up to 1500PPM.

59

Practically TDS can be totally removed from water but it can be separated by using reverse osmosis process. A typical reverse osmosis plant consists of a membrane made of poly amide in a spiral wound form. The water is allowed to pass through this membrane at a very high pressure. The permeate that comes out of the membrane will have a very less TDS. The solvent which isn’t allowed to pass consists of very high TDS, which is drained out through a reject pipe. TDS shouldn’t be too less also in water for HVAC application for the sole reason that it has to perform its basic function. Practically very less TDS water may not do the function of heat exchange with refrigerant inside the condenser. Hardness: Hardness of water is due to the presence of calcium and magnesium ions in water. Higher quantities of calcium and magnesium makes the water very hard or also called hard water. Hard water may cause corrosion when it traverses through metal tubes. Hence hardness of water should be minimum. Total harness of water is the sum of total calcium and total magnesium ions in water. Generally hardness of water used for cooling tower makeup can be up to 50 depending on optimum COC at condenser basin it can be up to 200PPM. Water hardness can be controlled by using a softener plant. Softener plant consists of vessel with resins packed inside it. The resins are golden colored spherical forms and have sites on its surface which is sodium ion rich. The hard water having ions like ca2+, mg2+ when flowing in opposite direction happened into this na+ ion of gradually the ca+ and mg2+ gets reduced and thereby hardness of water also gets reduced. Once na+ ions are replaced with ca2+ and mg2+ ions they are regenerated by using water contains salt solution (NACL). Then the resins are changed within fresh sodium ion and ready to take on harness of water. Silica: Silica is the compound of silicon and oxygen. Silica content in water can form scale deposits on metals where water comes in contract. It is advisable to crack and ensures silica or Sio2 is less than 50PPM at condenser basin. Chloride: Chloride ions constitute total mineral content in water. It is collateral increase salinity in water. In makeup it is optimum to have less than 50PPM and in the condenser depending on COC program it should be less than 200PPM. If the above parameter especially PH hardness and TDS are not controlled properly it is evident that metals corrode form scales, cause bio fouling on the system which would decrease the system performance and efficiency. It would be time consuming and expensive to charge the metal pipes remove scales etc. Hence it is necessary to protect the process equipment’s against above variances of water parameters. An ideal cooling tower condenser water dosing system should consist features to overcome 1. To remove coarse debris and larger life forms.

60

2. To remove fine suspended matter to prevent erosion and to prevent the formation of accumulations of material which would adversely affect heat transfer and possibly induce corrosion Also, large accumulation of settled out solids can choke cooling system including cooling tower ponds 3. To remove excess free carbon dioxide (CO2) and iron/manganese present in water particularly in case of ground water More CO2 than equilibrium is aggressive, while less from equilibrium can give rise to calcium carbonate (CaCO3) scale formation. Similarly, large 1 amount of iron and manganese can foul the tubes and induce corrosion. 4. To inhibit the growth of micro-organisms on heat exchange surfaces 5. To prevent the formation of scale this would affect heat transfer and impede flow of water. Though calcium bicarbonate is by far the most common scale found in cooling water system, attention should also be paid on less commonly found scale like calcium sulphate, calcium phosphate, magnesium silicate, etc. 6. To remove the corrosive potential of the cooling water due to dissolved oxygen, dissolved or suspended salts, alkaline or acidic water velocity, temperature, microbial growth, etc. Let us now have an insight of water parameters used in the cooling tower application above for last 9 months. In this application tanker water (water from bore wells) is used.

1. Condenser water

61

s.no month TDS Hardness Chloride silica

1 14-Dec 3560 1075 130 90

2 15-Jan 3280 1000 130 70

3 15-Feb 2950 950 130 70

4 15-Mar 2710 800 130 70

5 15-May 3520 1150 130 70

6 15-Jun 2450 725 130 50

7 15-Jul 3200 825 130 70

8 15-Aug 4050 1050 130 80

9 15-Sep 2610 575 130 70

10 15-Oct 2490 550 130 60

Condenser water

0

500

1000

1500

2000

2500

3000

3500

4000

4500

14

-De

c

15

-Jan

15

-Fe

b

15

-Mar

15

-May

15

-Ju

n

15

-Ju

l

15

-Au

g

15

-Se

p

15

-Oct

1 2 3 4 5 6 7 8 9 10

TDS

Hardness

Standard condenser

TDS

Standard condenser hardness

62

2. Makeup water

0

20

40

60

80

100

120

140

160

180

200

14-Dec 15-Jan 15-Feb 15-Mar15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct

1 2 3 4 5 6 7 8 9 10

Chloride

silica

Standard condenser chloride

Standard condenser silica

s.no month TDS Hardness Chlorine Silica

1 14-Dec 780 250 40 10

2 15-Jan 780 250 40 10

3 15-Feb 780 250 40 10

4 15-Mar 800 250 40 10

5 15-May 760 250 40 10

6 15-Jun 820 275 40 10

7 15-Jul 800 270 40 10

8 15-Aug 810 270 40 10

9 15-Sep 810 200 40 10

10 15-Oct 800 200 40 10

63

0

100

200

300

400

500

600

700

800

900

14-Dec 15-Jan 15-Feb 15-Mar 15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct

1 2 3 4 5 6 7 8 9 10

TDS

Hardness

Standard TDS makeup

Standard hardness makeup

0

5

10

15

20

25

30

35

40

45

50

14-Dec 15-Jan 15-Feb 15-Mar 15-May 15-Jun 15-Jul 15-Aug 15-Sep 15-Oct

1 2 3 4 5 6 7 8 9 10

Chlorine

Silica

Standard chloride makeup

Standard silica makeup

64

COC Limiting factors: Higher cycle of concentration is advantageous form saving of water as in the water passes form cooling tower through header pipes to the condenser of the chiller and returns till it is lost in blow down. This is considered as a cycle of water journey. On the other hand keeping large COC tend to increase the ca+ and mg+ ions in the water leading to hardness thereby lead to scaling. Hence it is advisable to keep the COC optimum following in the concerns arising out of variances of water. Corrosion:-Water when contact with metal surface converts metal into its oxide. The metal then starts slowly dissolving; this is mainly due to high mineral deposition in water and presence of oxygen. Scaling:- As mentioned earlier calcium and magnesium ions in water constitute into hardness. They are usually soluble in water with higher concentration they tend to lose their solubility called inverse solubility. They precipitate out and tend to deposit on the metal surface. These

Makeup water for

cooling tower

65

deposits are called “scale” the scale formation limits heat exchange capability of the system. It lets uncontrolled they lead to puncture/failure of metal due to impending thermal stress. Fouling:- water contains suspended foreign particles of all kind. The suspended foreign particles are usually process oils, fine dust particles or flying particles. Fouling occurs due to poor water flow low pressure, exposure of cooling tower to contract areas, mining etc. these particles come out of the solution and form deposits like scale. Similar to scales they affect heat exchangers capabilities and reduce thermal surface area thereby reducing overall efficiency of cooling tower. Fouling usually happens when NTU>5, large NTU’s are indication of higher fouling. Biofilms/Algae content: - Water also contains microorganism’s species of different kind. These microorganisms/algae secrete matter called slim. These are sticky in nature and sticks to the fills etc thereby blocking free water flow and reducing water pressure. They indirectly lead to corrosion through the process of metabolism leading to uncontrolled corrosion. Treatment Options Traditional water treatment programs are designed and implemented to account for the system concerns outlined above. This ensures the tower system operates optimally and achieves the needed cooling requirement. These programs consist of chemical additives including corrosion inhibitors, dispersants, scale inhibitors, and biocides that function to protect the cooling system and keep heat exchange surfaces clean and free of deposits or bio-films. When this is accomplished, maximum cycles of concentration can be achieved, and the cooling system can be operated at peak efficiency both in terms of water use and energy use. Beyond traditional water treatment programs there are options to build upon the current program, improve the current program, or replace the current program.

66

Auto Dozing system skid

Auto dozing system in cooling tower is recommended if despite recharging chemical program and using proper chemicals the parameters are shooting up. If nothing can be done on design of cooling tower, if it can’t be re-posited, if water can’t be retreated then it is best to install an auto dozing system with a program where chemicals are dozed automatically as varied parameters the values are permanently recorded through probes and controller via a control panel. As and when parameter vary beyond the set/desired value then the probe/sensor signals the dozing pumps to doze the required quantity into cooling tower and dozing continues till the parameters are well within the set values Side stream filter: If fouling in cooling tower is very high then side stream filter is recommended sometimes. It is possible to control scale formation but fouling will be high due to entry of foreign particles. Ideally in water sample of cooling tower the turbidity should be maintained less than 5 NTU. If it’s more and as mentioned earlier position of cooling tower can’t be changed from side stream filter to be installed which prevent the fouling/foreign particles entering into the condenser.

Dozing Tank

Dozing Pump

Electrical panel

67

The sample showing increase in turbidity of CT water and as per lab analysis report is shown below.

Summary of observation for improving the system Additional cooling tower might be required to enhance the condenser water flow rate and keep a good approach temperature in case the problem does not solve after the below mentioned remedies as its observed the cooling tower isn’t well installed and hence deration might be one of the reasons apart from below observations 1. Chiller condenser descaling.

68

2. Secondary pump in Auto mode commissioning. 3. Balancing of chilled and condenser water flow rates for entire plant and low side works. 4. Checking/ Rectifying / Making chilled water two way valves functional for Tenant areas. 5. Implementation of Automation system of chemical dosing to ensure scientific dosing else chemicals would get wasted and not useful. 6. Cooling tower maintenance contracts. 7. All Pump flow checks- using flow meters. 8. Overall operation of plant and logs to be maintained by professional agency with AMC for all critical systems Chillers , pumps , cooling towers , water balancing etc.

69

CHAPTER 4

AIR HANDLING UNIT ROOMS

70

AIR HANDLING UNIT ROOMS

The air handling units are very important parts of the central air conditioning plants, packaged air conditioning plants and also the roof mounted split air conditioning systems. As the name suggests air handling unit is the box type of unit that handles the room air. It comprises of the cooling coil over which the hot return air from the room flows, gets cooled and flows back to the room to cool it. The circulation of the air is carried out by the blower. The filter in the air handling unit enables cleaning of the air. The air handling units are also called as fan coil units in case of roof mounted split AC units, since they comprise of the fan and the cooling coil. The air handling units are installed at the different places in the building to be air conditioned. They are connected to the cool air supply and return air ducts which are laid in all the rooms to be cooled. In case of the central air conditioning plants the air handling units are installed on the floor, while in case of the split air conditioners, they are mounted on the roof inside the room above the false ceiling. In case of packaged units they can be installed on the floor or the roof.

The air handling units are installed in the various parts of the building that are to be air conditioned, in the place called air handling unit rooms. The air handling units comprise of the cooling coil, air filter, the blower and the supply and return air ducts. The chilled water flows through the cooling coil. The blower absorbs the return hot air from the air conditioned space and blows it over the cooling coil thus cooling the air. This cooled air passes over the air filter and is passed by the supply air ducts into the space which is to be air conditioned. The air handling unit and the ducts passing through it are insulated to reduce the loss of the cooling effect.

71

AHU filters

Chilled water inlet and outlet

Filters

Inlet

water

Outlet

water

72

Blower and pulley:

Sweating:

Pulley

Sweating

Blower

Motor

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Maintenance of AHU’s: AHU’s are an integral part of HVAC towards the low side. It is the main area which caters cooling tower and humidity control at the area where it is intended. If cooling is desired temperature in the area is not achieved then first aspect any engineer/technician looks into the AHU whereas the name indicates Air Handling unit that takes place. In most of the common area the problem associated with AHU of the blower design inadequate or the blower motion rotary in opposite direction. The design of the blower has to be taken care of in the design stage itself depending on the CFM/ air flow the air handle is intended to give. In usual practice as far as maintenance are concerned the following is looked into checking the terminal of blow motor blower technically the amps of 3ø that is RYB to be checked using a clamp meter. There will be a design rating on the terminal for example if design rating is 10A then R=8.5A Y=9A B=9A If the results are greater than 6A on each phase then the terminals are healthy and it is understood that they are taking equal load. But if found less than 6A then pulley of blower and motor to be checked and replaced, lesser the pulley diameter more the rotation given by formula

The rotation of blower and motor can be checked using a tachometer which shows the speed (N) in the unit of revolution per minute. The motor and blower are connected by means of a transmission belt. These belts are usually made of rubber material and available in various sizes. It is mandatory to inspect the tension of belts and periodically change it if much wear and tear is to be found.

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a. Filters: Filters are an important part of AHU. The filters prevent the solid, dust and

other suspended particles entry into the unit and thereby ensuring good quality of air coming to common area. Commonly filters are available in various sizes. The filter capacity is mentioned in microns (10^-6). Less the microns more is its filtering capacity. In simple words, even the minute particles aren’t allowed to pass through. Below mentioned is the list of AHU filters with their dimension and quantity floor wise at a retail area.

S.no Floor AHU Number

Width Height Diameter Quantity

1 LG AHU1 475 630 48 8 2 LG AHU2 565 760 48 8

3 LG AHU3 562 760 48 8

4 LG AHU4 475 765 48 8 5 LG AHU5 610 610 48 8

6 LG AHU5 610 305 48 4 7 UG AHU1 510 630 48 6

8 UG AHU2 760 610 48 9 9 UG AHU3 760 630 48 4

10 UG AHU4 760 560 48 9

11 UG AHU5 560 760 48 4 12 UG AHU6 560 760 48 8

13 FF AHU1 760 630 48 4

Filters

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14 FF AHU2 760 610 48 9

15 FF AHU3 760 630 48 4 16 FF AHU4 575 510 48 12

17 FF AHU5 760 560 48 4 18 FF AHU6 640 640 48 6

19 FF AHU7 610 610 48 4

20 FF AHU7 305 610 48 2 21 SF AHU1 760 630 48 4

22 SF AHU2 760 610 48 9 23 SF AHU3 760 630 48 4

24 SF AHU4 760 500 48 9

25 SF AHU5 760 560 48 4 26 SF AHU6 760 630 48 4

27 SF AHU7 610 610 48 4 28 SF AHU7 305 610 48 2

LG - Lower Ground floor UG - Upper Ground floor FF - First floor

SF - Second floor

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AHU test with BMS: Below mentioned is the tabulated record of chilled water inlet and outlet temperatures at AHU. It is to be note that wherever the chilled water inlet and outlet temperature differences are <4° C, then the indication is that enough heat exchange not happening at coils. Physically good sweating is an indicator that good heat exchange is happening. The temperature difference and inlet and outlet of AHU’s to be equal to 4°C. Beyond 6°C, then it is again indicator that coils are blocked and requires cleaning.

Floo

r

AHU

no inlet outlet

delta

temp

filter

status

supply

Dampe

r status

return

Damper

status Sweating Status Remarks

LG AHU1 9.8 14.6 4.8 normal normal normal normal none

LG AHU2 10.1 14.3 4.2 normal normal normal normal none

LG AHU3 9.2 11.2 2 normal normal normal Less sweating

coil is bloked & belt is loose, Dscaling

to be done

LG AHU4 10.2 16.4 6.2 normal normal normal Less sweating AHU Dscaling to be done

LG AHU5 10.8 13.5 2.7 normal normal normal Less sweating AHU Dscaling to be done

UG AHU1 7.9 12.6 4.7 Normalnormal normal normal none

UG AHU2 8.1 15.3 7.2 Normalnormal normal Less/No sweting AHU Dscaling to be done

UG AHU3 8.5 13.4 4.9 Normalnormal normal normal none

UG AHU4 7.9 13.3 5.4 Normalnormal normal normal none

UG AHU5 8.3 12.3 4 Normalnormal

one not

connect

ed to normal none

UG AHU6 9.6 12.4 2.8 Normalnormal normal Less/No sweating AHU Dscaling to be done

FF AHU1 8.4 12.1 3.7 normal normal normal Less/No sweating AHU Dscaling to be done

FF AHU2 8.2 11.2 3 normal

one not

connec

ted to normal Less/No sweating AHU Dscaling to be done

FF AHU3 8.4 13.3 4.9 normal normal normal Normal none

FF AHU4 8.7 14.1 5.4 normal normal normal Normal Shaft inside AHU is open

FF AHU5 7.8 12.7 4.9 normal normal normal Normal none

FF AHU6 7.8 12.4 4.6 normal normal normal Normal none

SF AHU1 9.4 11.7 2.3 normal normal normal Less/No sweating AHU Dscaling to be done

SF AHU2 8.4 17.2 8.8 normal normal normal Normal

On/Off condition is not being showed

in graphs, Dscaling to be done

SF AHU3 8.6 14.2 5.6 normal normal normal Normal none

SF AHU4 8.4 14.9 6.5 normal normal normal Less/NO SWEATINGAHU Dscaling to be done

SF AHU5 7.8 12.7 4.9 normal normal normal Less/No sweating none

SF AHU6 7.8 12 4.2 normal normal normal Less/No sweating none

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Differential pressure switch connected to BMS to know the filter status

Temperature inlet and outlet sensors connected to BMS

Refer BMS in appendix

78

Actuator:

Actuator

79

CHAPTER 5

GRILLS LOW SIDE

80

Grills Low side:

On the low side the conditioned air is transported from the air handling unit to the area which needs to be cooled via ducts usually made of Galvanized ions. The common ducts will be running floor wise further branched to areas to be cooled. The point where air throw takes place through a diffuser commonly named as grills. The grills are available in various sizes and shapes. The commonly found grills are in the shape of circular, rectangular and square type. The main ducts are connected to grill via a collar which is usually made of galvanized ion.

Commonly in most of the application of the low side, the difficulties found are the collar

connection from the duct to grill is improper, omission of collars itself or grills offset to collar. These difficulties arise when CFM checks where conducted on the grills. It is a difficult to correct these offsets in a running operation and rather it should have been corrected during the commissioning stage itself.

Standard CFM – 556 Grill Size – 4’X4” Area – 1.33 Sq.ft

81

Rectangular

return air grill

Rectangular

supply air grill

Square supply

air grill

82

Round diffuser

Rectangular air

supply grill

Insulated

supply air Duct collar

83

Below mentioned is the floor wise CFM reading taken at grills on a four story building using formulas mentioned above.

Rectangular air

supply grill

Ceiling

suspended unit

(AHU)

84

NAME

GRILL SIZE Ft

1 2 3 4 5 AREA sqft

AVERAGE

AVERAGE CFM

STANDARD

EXCESS

LOW

NIL

xxx 4'x4" 0 0 0 0 1.3333

0 0 556 556

xxx 4'x4" 0 0 0 0 0 1.3333

0 0 556 556

xxx 4'x4" 0 0 0 0 0 1.3333

0 0 556 556

xxx 4'x4" 150

150

150

1.3333

150 200 556 356

xxx 4'x4" 0 0 0 0 0 1.3333

0 0 556 556

xxx 4'x4" 250

150

380

1.3333

260 347 556 209

xxx 4'x4" 743

453

490

1.3333

562 749 556 193

The above chart shows the CFM readings taken floor wise in an operational commercial building. This chart is a clear indicator that the design CFM in each grill viz-a-viz is actual CFM in each grill. Where ever the actual CFM is shown less than the designed CFM then it is understood that there is no collar connectivity to the grill or the grill and the collars are offset. There is also possibility that there is air loss in the duct due to minor holes or duct joints. Note the readings are taken when AHU’s of the particular zone are in ON condition. The problems related to AHU’s are already mentioned elsewhere. Even the AHU’s to be checked for CFM readings at AHU supply duct.

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APPENDIX

Automation Automation systems are available providing a broad range of capacities to control single or multiple parameters in the cooling system such as conductivity and blow down control, pH control, and real-time chemical monitoring and dosing. Blow down controllers are available from several different commercial suppliers and offer a range of control points from simple conductivity/blow down control, to timed or meter relay chemical dosing. Many of them incorporate water meter inputs and alarm relays if threshold measurements are exceeded. Blow down controllers offer continuous monitoring and control of the blow down of the tower system. This ensures high conductivity is avoided, minimizing scaling and corrosive conditions and minimizes excessive blow down which wastes water. Blow down control and the other showing blow down controlled with a conductivity controller. The impact of implementing blow down controllers, revealing conductivity rates that stay much closer to the ideal set point compared to manual control. More robust automation platforms are also available from several manufacturers that provide system-wide monitoring and dosing. These platforms are scalable depending on the need, but offer conductivity/blow down control, pH control, real-time chemical monitoring and dosing, continuous corrosion monitoring, web-enabled reporting, and alarm relays. The benefit of these systems is tightened control of the various control points of the water treatment program, not only eliminating excessive water use and high cycle conditions, but also controlling chemical residuals and treatment dosing based on real-time corrosion and scaling indices. In trend terms, similar results to the conductivity improvements can be achieved on chemical treatment residuals, pH set point and acid feed, biocide dosing, and corrosion monitoring. The performance improvement real-time dosing achieves on chemical residuals, ensuring the proper dosage of corrosion and scale inhibitors at all times and eliminating overfeed or underfeed of charge of harmful or illegal substances. Filtration Filter systems are nothing new to industrial water systems, and have been used as pre-treatment in many different applications for many years. In recent years, side-stream filtration systems have become popular among many water treatment professionals. They function to remove suspended solids, organics, and silt particles down to 0.45 microns from a portion or all of the system water on a continual basis, thereby reducing fouling, scaling and microbiological activity. This allows the cooling system to work more efficiently and often reduces the amount

86

of water blown down. However, the net impact on water consumption must consider the fact that these platforms require back-washing to clean the filter system. The amount of water used to regenerate the filter system should be added to the water lost due to evaporation and blow down. Water Treatment Plant: The water used for HVAC system is filtered through a treatment process. The plant which treats this is called WTP. It consists of dual media filter and a mild steel vessel with rubber lining inside. The raw water (from bore tankers etc.) is passed through this treatment process to optimize the parameters and rendering it fit for use into system. Dual media filter: This is basically a vessel which consists of layers of sand and charcoal. The dual media does a dual function of removing suspended solids in water (sand) and organics especially Chlorine (activated carbon). Selected grades of sand are mixed together in fixed proportion. It is supported by gravels and pebbles. This allows the filter to work using surface filtration and depth filtration, thus allowing higher dirt holding capacity. It is externally fitted with necessary pipe work, manual valves, pressure gauges and sampling points at the inlet and outlet. A flow indicator, Rota meter type is provided in the inlet line to observe the flow during service/backwash. Raw water flows downwards through the filter bed and suspended matter is retained on the sand surface and between the sand grains immediately below the surface. The filtered water is evenly collected by strainer on plate type bottom collecting system. Operation on Dual Media Filter Backwash: Water is passed upwards through the column from bottom to top and then discharged to the drain for 10 minutes or till the effluent is clear, at required flow rate. This results in removal of free impurities from the sand bed. Rinse: Water is passed downwards through column. The water flows out through the bottom collector and flows to drain. The required flow rate is maintained by use of Rota meter till the effluent is clear for approx. 5 minutes. The above is recommended everyday Softener: Softener vessel consists of resin, which is golden coated. The resins have pores on its surface. It has free ions on its surface. Generally the free ions are sodium ions which can be replaced with other ions. Hardness in water is due to presence of Ca2+ mg+ ions. As the water passes through softener vessel, the ions are replaced with sodium ions over a period of time as the flow continues the hard ions over a period of time as the flow continues, the hard ions are replaced and water becomes soft as it continues to move faster. Equipment details: this is MSEP pressure vessel. Externally the unit is provided with frontal piping with necessary valves, pressure gauge and sample valve at the inlet and outlet brine

87

measuring tank and ejector for the injection of the brine solution in the tank. Internally the unit is provided with inlet distributor and bottom collection system for collecting water during service and distribute during backwash operation. Operation on Softener Plant Regeneration: When the supply of exchangeable ions within resin is exhausted, the treated water from resin deteriorates and the resin requires regeneration-reconversion of the resin into the operating form. In normal practice common salt ( NACL) is mixed with water and injected for regeneration activity. For a 400 m3/hr plant 220 Kgs of salt is to be used. As a good maintenance practice, regeneration is to be done every day. Building Management Systems (BMS) : The Integrated Building Management System (IBMS) supplier shall furnish and install a fully Integrated Building Automation System, incorporating direct digital controllers (DDC) for energy management, equipment monitoring and control, suitable for the building usage. The control strategies shall be developed to ensure that the specified project conditions are maintained, whilst giving due regard to minimizing of energy consumption.

Integration of the system shall mean that all the parts of the system are connected together through software program, electronic components and hardware packaging and communication network.

To provide maximum flexibility and to respond to changes in the building use, the system offered shall support the use of BACnet/ LON works, Profibus and Ethernet TCP/IP communication technologies and through DDC controller for system of electrical equipment’s, Electrical energy monitoring FAS, PAS, ACS controls ,CCTV ,Fire Pumps, water transfer & Booster Pumps, STP pumps, HVAC Systems, fresh air fans, smoke & toilet exhaust fans, jet fans, UPS, DG set etc.

The system design shall utilize the latest technology in “open” network architecture, distributive intelligence and processing, and direct digital control. The IBMS system offered should be from the latest offerings and should be of freely programmable management and automation stations for the full spectrum of today’s building application services.

88

DDCP :-

The out-station panel housing the DDC controllers shall be located inside the conditioned area. Proper care shall be taken to ensure that there is no induction problem between the control and power cables. These panels shall be IP54 and supplied by the specialist controls supplier.

The DDC controllers located inside these out-station panels shall provide the required signals to the various equipment’s connected to these DDC controllers. The DDC controllers shall be capable of accepting digital input signals in the form of volt-free contacts from Motor Control Centers. The MEP contractor shall co-ordinate this activity with the IBMS contractor.

All these outstations shall be connected with a communication bus cable and terminated to the IBMS central station. The IBMS supplier shall supply these bus cables.It shall be possible to connect the Portable hand held terminal to be connected to any of these panels and talk to any other DDC controllers on the same bus.

89

Relative humidity and ambient temperature:

Display of chiller connected to BMS:

DDC panel

90

Display of cooling tower connected to BMS:

Display of AHU connected to BMS:

91

QUESTIONS TO BE PONDERED ON CHEMICAL TREATMENT OF HVAC SYSTEM

Facility name: Address: Concerned Department and person:

1. As you understand your cooling system requirements; which option you would like to opt in

terms of quality and price associated with maintenance of the system. High price – High Quality Low price – Low Quality Medium price – Medium Quality

3. How are you dosing your products?

Manually Based on flow Timer Automated controller Other

4. Is the CW system difficult to control (in terms of chemical dosage, maintaining the desired

cycles, etc.)? Yes No Sometimes (Please explain)

5. Are there wide variations in make-up water quality?

Yes No Sometimes

6. Are you looking for the option of less human intervention at your site?

Yes No

7. Is there a propensity for fouling/scaling?

Yes No

92

8. Are there any corrosion issues? Yes No

9. Are there any microbial issues?

Yes No

10. How critical is the CW operation?

Very critical Critical Not critical

11. Does the system need to run 24/7?

Yes No

12. Impacts of shutdowns/maintenance? Very High High low

13. Any environmental discharge concerns? Yes No If yes, please explain

14. How important are sustainability factors (water usage, energy usage, etc) to you? Very important Important Not important

15. Would you be interested in a ‘Green technology that will bring down your total cost of operations in future? Yes No

16. Are there any other operational issues? Yes (please explain) No

93

17. Would you like a team of experts to monitor your systems 24/7?

Yes, but at no extra cost Yes and I am ready to pay some reasonable amount for that I don’t think its required

18. If there is an upset in your system, how fast would you like to get notified? Within 30 minutes Within 30 to 60 minutes Within 2 hours I don’t need any notification

19. Would you like to receive monthly/weekly reports on the performance/health of your cooling water system? Yes. Monthly/weekly No

20. As world is becoming so advance in terms of technology and quick response, Do you feel that your asset performance and water analysis details should be at your fingertips? Strongly agree Moderately agree Agree Moderately disagree Strongly disagree

21. How important technology is for you? Would you like to use a state of the art technology that comes at a reasonable cost? Yes No

22. You are primarily bothered regarding which type of cost? Maintenance and shutdowns Water Energy Labor Chemical Any other

23. Please list down all your key drivers (water cost, water usage, energy cost, total cost, etc) for CW operations?

24. What is annual CW chemical usage? 25. What is existing contract type? Fixed basic agreements or variable based on actual

consumption?

94

26. In case you want install automated equipment for chemical dosing, what type of payment option you would prefer? Would you like it on rent or complete buy-out? No. of rooms Area of SQ Meter or Sq. ft No of cooling towers: CW system volume: No. of chillers Chiller tonnage: Blow down (COC): Annual usage of water MU cost Sewage cost Average cost related to chemical treatment (Per annum) Electricity/Energy usage cost(For the chiller) Any sustainability/green goal: Annual maintenance cost Regulatory costs Labor costs Other critical factors Any other performance related measures

95

General information:

Chillers

Type Make Capacity

(TR) Nos

Chilled Water Set Point

With VFD(Y/N)

Centrifugal xxxx 800 3 N/A N

Secondary Pumps Condenser Pumps

Qty Make Flow

(USGPM) Head (Mtrs)

KW With

VFD(Y/N) Qty Make

Flow (USGPM)

Head (Mtrs)

KW With VFD

(Y/N)

5 yyy 1198 38 37 Y 4 yyy 2400 24 45 N

Cooling Towers Hours of Operation per day

Qty Make Capacity

TR

Design Approach

- Deg F

No. of Fans-

Each CT Fan KW

With VFD(Y/N)

3 zzzz 800 7 4 7.5 N 14

96

Building energy data:

Oct-15

KWH Rs

1519600 12572782

KWH Rs KWH Rs KWH Rs KWH Rs

1618400 13516677 1653600 12920031 1654400 12896818 1580400 12364534

Jun-14 Jul-14 Aug-14 Sep-14

KWH Rs KWH Rs KWH Rs KWH Rs

1622000 12655163 1525200 11953811 1546400 12141583 1542400 12109553

Nov-14 Dec-14 Jan-15Oct-14

KWH Rs KWH Rs KWH Rs KWH Rs

1378400 10945281 1563200 12235577 1476800 12092471 1737600 14431550

May-15Mar-15 Apr-15Feb-15

KWH Rs KWH Rs KWH Rs KWH Rs

1703600 14514277 1738400 14305375 1695600 13918760 1474400 12298743

Jun-15 Jul-15 Aug-15 Sep-15

97

Chiller energy data:

Pumps energy data:

KWH Rs KWH Rs KWH Rs KWH Rs

216253 1654335 201049 1538025 196940 1506591 265418 2030447.7

Jun-14 Jul-14 Aug-14 Sep-14

KWH Rs KWH Rs KWH Rs KWH Rs

267585 2047025.25 213889 1636250.85 202174 1546631.1 204129 1561587

Dec-14 Jan-15Oct-14 Nov-14

KWH Rs KWH Rs KWH Rs KWH Rs

177842 1360491 239539 1832473 290160 2219724 325890 2493059

Feb-15 Mar-15 Apr-15 May-15

KWH Rs KWH Rs KWH Rs KWH Rs KWH Rs

308202 2357745 308184 2357608 293247 2243340 265103 2028038 281455 2153131

Jun-15 Sep-15 Oct-15Jul-15 Aug-15

KWH Rs KWH Rs KWH Rs KWH Rs

86333 660447.5 84551 646815.2 79362 607119.3 75477 577399.05

Jul-14 Aug-14 Sep-14Jun-14

KWH Rs KWH Rs KWH Rs KWH Rs

81148 620782.2 71741 548818.65 73860 565029 68762 526029.3

Dec-14 Jan-15Oct-14 Nov-14

KWH Rs KWH Rs KWH Rs KWH Rs

58212 445321.8 108925 833276.3 123801 947077.7 133041 1017764

Feb-15 Mar-15 Apr-15 May-15

KWH Rs KWH Rs KWH Rs KWH Rs KWH Rs

128576 983606.4 128465 982757.3 123848 947437.2 110739 847153.4 120143 919094

Jun-15 Jul-15 Aug-15 Sep-15 Oct-15

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Cooling tower energy data:

KWH Rs KWH Rs KWH Rs KWH Rs

302586 2314783 285600 2184840 276302 2113710.3 340895 2607846.75

Jun-14 Jul-14 Aug-14 Sep-14

KWH Rs KWH Rs KWH Rs KWH Rs

348733 2667807.45 285630 2185069.5 276034 2111660.1 272891 2087616

Dec-14 Jan-15Oct-14 Nov-14

KWH Rs KWH Rs KWH Rs KWH Rs

236054 1805813 348464 2665750 413961 3166802 458931 3510822

Feb-15 Mar-15 Apr-15 May-15

KWH Rs KWH Rs KWH Rs KWH Rs KWH Rs

436778 3341352 436649 3340365 417095 3190777 375842 2875191 401598 3072225

Jun-15 Jul-15 Aug-15 Sep-15 Oct-15

99

ANNEXURE FOR HVAC System

100

Specifications for HVAC system

1 Details on Air Conditioning System Ductable Type centralised system

2 Total Capacity of Air Conditioner 3 x 800TR

3 Total Area of Air Conditioned Space

Length X Width

Height of the false ceiling from FFL

4 Type of Ceiling POP false ceiling at common area and

open to waffle ceiling at retailers and

other areas

5 Height of Building from ground floor

6 Is the Space divided in floors

YES ( GF UG FF SF)

7 Maximum Number of people to occupy the Space

75000 on an average

8 Is CAD drawing available for the Space Layout

9 Temperature to be maintained

24 +/- 3 °C

10 Humidity level to be maintained

50 +/- 10

11 Wall thickness

12 Material used for construction of Wall & Ceiling POP Board –Ceiling

101

Plastered Brick Wall

13 Specify provision of insulation for the walls and ceiling Masonry Hollow block wall and POP

ceiling

14 Specify Material of insulation

15 Total Number of Electrical Appliances installed in the Space

.

16 Specify the Total Wattage of the Electrical Appliances KW lighting

17 Provision of Windows in the Space

18 Specify the Number of windows

19 Specify the type of windows

20 Specify the Total area of all windows

.

21 Are Dust Collectors installed inside the Working Air

Conditioned space

No

22 Specify the Total number of dust collectors occupying the

space

NA

23 Specify the specification of each dust collector in terms of

the Air extraction Capacity

NA

102

24 Total Wattage of the Machineries Installed in the Air

Conditioned Space

2 Ball Mills: 15KW

2 Vibrating Tables :7.5KW

& OTHERS

25 Total Heating Load present in the Space

All types of leakages possible to occur from this place must be specified. There are two doors for man &

materials movement. The frequency of operation of the door will be 4times in an hour.

Other Relevant Data:

1. Bengaluru ambient conditions are

Summer- 110 deg F and 78 Deg F, mean relative humidity 24%,

Monsoon- 88 deg F and 79 Deg F, Mean relative humidity- 68%

Winter - 50Deg F and 43 Deg F, mean relative humidity - 58%

2. Total Moisture Load In the area: Maximum. 300Kg

1. Air-conditioned & dehumidified area but it is not a cleaned room application.

26 Common Floor Utility Service Available

Electrical Service

Voltage: 415 ± 10%

Phase: 3-Phase + Neutral Earth

Frequency: 50 Hz ± 3%

27 Preferred Voltage At Equipment For

Control Panel 440 Volts AC

103

Field Equipment 24 Volts DC

28 Motors

Preferred Motor Specifications

415 Volts AC

3-Phase Induction Motor, Foot Mounted, TEFC, IP-

55 Protection, Class-F Insulation, EFF1

29 Electrical Panel

External, Remote Located Unit

30 Safety Protections Supplier to include all Safety Protections for the

Equipment as required for the Operation and

Maintenance as per relevant CE Standard

Guidelines applicable for Industrial Gas Fired

Appliances and Safety of Electrical / Electronic

Systems & Devices associated with the Equipment.

LOTO Provision should be Built-in for all Energy

Sources (Electricity, Hydraulic, etc as applicable)

with-in the Equipment Battery Limit.

Platform hand railing with toe guards in case of

suspended chilling system.

Safety protection for hydraulic hose/tube failure

31 Equipment Noise Level Limitation Should be less than 85 DBA measured at 1m distance

from source.

32 Scope Of Supply Design and Supply of the chiller, cooling tower,

AHU and ducting system to Meet Specifications.

Supplier Documentation along with CE Certification

for The Equipment Supplied.

Recommendations and Price Quote for Spares to

be maintained.

Operation and Maintenance Manuals: 2sets each of

Hard Copy and Soft Copy in CD.

Any other accessory specifically not indicated but

essential for the Equipment Safety or Operation.

104

CONCLUSION

The Goal— an Environmentally Friendlier, Energy-Efficient, and Cost-Effective HVAC&R System The goal is to provide an HVAC&R system which is environmentally friendlier, energy-efficient and cost-effective as follows:

Effectively control indoor environmental parameters, usually to keep temperature and humidity within required limits.

Provide an adequate amount of outdoor ventilation air and an acceptable indoor air quality.

Use energy-efficient equipment and HVAC&R systems.

Minimize ozone depletion and the global warming effect.

Select cost-effective components and systems.

Ensure proper maintenance, easy after-hour access, and necessary fire protection and smoke control systems.