HVAC DESIGN HVAC DESIGN HVAC DESIGN HVAC DESIGN

WHAT IS HVAC ?

HVACHVACHVACHVAC ((((heatingheatingheatingheating,,,, ventilationventilationventilationventilation, and, and, and, and air conditioningair conditioningair conditioningair conditioning) is the technology of indoor ) is the technology of indoor ) is the technology of indoor ) is the technology of indoor

and vehicular environmental comfort. HVAC system design is a and vehicular environmental comfort. HVAC system design is a and vehicular environmental comfort. HVAC system design is a and vehicular environmental comfort. HVAC system design is a sub discipline sub discipline sub discipline sub discipline

ofofofof mechanical mechanical mechanical mechanical engineeringengineeringengineeringengineering....

a)a)a)a) HeatingHeatingHeatingHeating

The temperature out side is less than insideThe temperature out side is less than insideThe temperature out side is less than insideThe temperature out side is less than inside

b) Ventilation b) Ventilation b) Ventilation b) Ventilation

Sending the air out from the space and /or supplying the fresh air into the Sending the air out from the space and /or supplying the fresh air into the Sending the air out from the space and /or supplying the fresh air into the Sending the air out from the space and /or supplying the fresh air into the

space .space .space .space .

c) Air conditioningc) Air conditioningc) Air conditioningc) Air conditioning

It mean a process by which the temperature,humidity,flowIt mean a process by which the temperature,humidity,flowIt mean a process by which the temperature,humidity,flowIt mean a process by which the temperature,humidity,flow and purity of the and purity of the and purity of the and purity of the

air is controlled simultaneously to get the required conditions.air is controlled simultaneously to get the required conditions.air is controlled simultaneously to get the required conditions.air is controlled simultaneously to get the required conditions.

WHY DO WE REQUIRE AIR CONDITIONING ?

1.1.1.1. To improve or control an industrial processTo improve or control an industrial processTo improve or control an industrial processTo improve or control an industrial process

2.2.2.2. To maintain human comfortTo maintain human comfortTo maintain human comfortTo maintain human comfort

MAN A HEAT MACHINE

� Food is the fuelFood is the fuelFood is the fuelFood is the fuel

� Every body movement s generate heat even the blink of an eye.Every body movement s generate heat even the blink of an eye.Every body movement s generate heat even the blink of an eye.Every body movement s generate heat even the blink of an eye.

� To maintain 98.6To maintain 98.6To maintain 98.6To maintain 98.6°°°°F , it reject heatF , it reject heatF , it reject heatF , it reject heat

In what way it reject heat?In what way it reject heat?In what way it reject heat?In what way it reject heat?

HEAT TRANSFER

1.1.1.1. ConductionConductionConductionConduction

2.2.2.2. ConvectionConvectionConvectionConvection

3.3.3.3. RadiationRadiationRadiationRadiation

CONDUCTION

The heat transfer due to conduction takes place if the two bodies at The heat transfer due to conduction takes place if the two bodies at The heat transfer due to conduction takes place if the two bodies at The heat transfer due to conduction takes place if the two bodies at

different temperature are in contact with each other . It is also true if a different temperature are in contact with each other . It is also true if a different temperature are in contact with each other . It is also true if a different temperature are in contact with each other . It is also true if a

substance is heated from one end , heat transfer take place to the substance is heated from one end , heat transfer take place to the substance is heated from one end , heat transfer take place to the substance is heated from one end , heat transfer take place to the

other end by conduction.other end by conduction.other end by conduction.other end by conduction.

CONVECTION

When liquid or gas is heated , expansion takes place. Due to this it becomes When liquid or gas is heated , expansion takes place. Due to this it becomes When liquid or gas is heated , expansion takes place. Due to this it becomes When liquid or gas is heated , expansion takes place. Due to this it becomes

lighter and rises up. Its place is taken by colder or dense fluid. This is a lighter and rises up. Its place is taken by colder or dense fluid. This is a lighter and rises up. Its place is taken by colder or dense fluid. This is a lighter and rises up. Its place is taken by colder or dense fluid. This is a

continuous process and thus heat transfer takes place due to these process and continuous process and thus heat transfer takes place due to these process and continuous process and thus heat transfer takes place due to these process and continuous process and thus heat transfer takes place due to these process and

heat is distributed through the mass.heat is distributed through the mass.heat is distributed through the mass.heat is distributed through the mass.

RADIATION

The heat transfer due to radiation takes place from one body to another without The heat transfer due to radiation takes place from one body to another without The heat transfer due to radiation takes place from one body to another without The heat transfer due to radiation takes place from one body to another without

effecting the medium through which heat travels. Heat flow from sun to earth effecting the medium through which heat travels. Heat flow from sun to earth effecting the medium through which heat travels. Heat flow from sun to earth effecting the medium through which heat travels. Heat flow from sun to earth

takes place in this fashion.takes place in this fashion.takes place in this fashion.takes place in this fashion.

EVAPORATION

Evaporation Evaporation Evaporation Evaporation is the process by which water is converted from its liquid is the process by which water is converted from its liquid is the process by which water is converted from its liquid is the process by which water is converted from its liquid

form to its form to its form to its form to its vapour vapour vapour vapour form and thus transferred from land and water form and thus transferred from land and water form and thus transferred from land and water form and thus transferred from land and water

masses to the atmospheremasses to the atmospheremasses to the atmospheremasses to the atmosphere. . . . EvaporationEvaporationEvaporationEvaporation of sweat from the skin surface of sweat from the skin surface of sweat from the skin surface of sweat from the skin surface

has a cooling effect due to thehas a cooling effect due to thehas a cooling effect due to thehas a cooling effect due to the evaporationevaporationevaporationevaporation of water.of water.of water.of water.

TTTThe he he he rate of evaporation depends upon:rate of evaporation depends upon:rate of evaporation depends upon:rate of evaporation depends upon:

Wind speedWind speedWind speedWind speed: the higher the wind speed, the more : the higher the wind speed, the more : the higher the wind speed, the more : the higher the wind speed, the more evaporationevaporationevaporationevaporation

TemperatureTemperatureTemperatureTemperature: the higher the temperature, the more : the higher the temperature, the more : the higher the temperature, the more : the higher the temperature, the more evaporationevaporationevaporationevaporation

HumidityHumidityHumidityHumidity: the lower the humidity, the more evaporation: the lower the humidity, the more evaporation: the lower the humidity, the more evaporation: the lower the humidity, the more evaporation

HUMIDITY

HumidityHumidityHumidityHumidity is the amount ofis the amount ofis the amount ofis the amount of water water water water vapourvapourvapourvapour (moisture)(moisture)(moisture)(moisture) in thein thein thein the airairairair. Water . Water . Water . Water

vapour vapour vapour vapour is the gas phase of water and is is the gas phase of water and is is the gas phase of water and is is the gas phase of water and is invisible. Humidity invisible. Humidity invisible. Humidity invisible. Humidity indicates the indicates the indicates the indicates the

likelihood likelihood likelihood likelihood of of of of precipitationprecipitationprecipitationprecipitation,,,, dewdewdewdew, or, or, or, or fogfogfogfog. Higher humidity reduces the . Higher humidity reduces the . Higher humidity reduces the . Higher humidity reduces the

effectiveness ofeffectiveness ofeffectiveness ofeffectiveness of sweatingsweatingsweatingsweating in cooling the body by reducing the rate in cooling the body by reducing the rate in cooling the body by reducing the rate in cooling the body by reducing the rate

ofofofof evaporationevaporationevaporationevaporation of moisture from the skin. This effect is calculated in of moisture from the skin. This effect is calculated in of moisture from the skin. This effect is calculated in of moisture from the skin. This effect is calculated in

aaaa heat indexheat indexheat indexheat index table, used during summer weather.table, used during summer weather.table, used during summer weather.table, used during summer weather.

RELATIVE HUMIDITY (RH)

It is the ratio of the actual moisture present in the air to the maximum moisture It is the ratio of the actual moisture present in the air to the maximum moisture It is the ratio of the actual moisture present in the air to the maximum moisture It is the ratio of the actual moisture present in the air to the maximum moisture

the air can hold in a particular temperature.the air can hold in a particular temperature.the air can hold in a particular temperature.the air can hold in a particular temperature.

Convection , radiation and evaporation Convection , radiation and evaporation Convection , radiation and evaporation Convection , radiation and evaporation

• All the 3 methods normally used at the same timeAll the 3 methods normally used at the same timeAll the 3 methods normally used at the same timeAll the 3 methods normally used at the same time

• All three methods gives off excess heatAll three methods gives off excess heatAll three methods gives off excess heatAll three methods gives off excess heat

• One method do more and other may do lessOne method do more and other may do lessOne method do more and other may do lessOne method do more and other may do less

• Depending on the surrounding conditions.Depending on the surrounding conditions.Depending on the surrounding conditions.Depending on the surrounding conditions.

What are the surrounding conditions?What are the surrounding conditions?What are the surrounding conditions?What are the surrounding conditions?

1.1.1.1. Temperature Temperature Temperature Temperature

2.2.2.2. Relative humidityRelative humidityRelative humidityRelative humidity

3.3.3.3. Air motionAir motionAir motionAir motion

Change in each of this surrounding condition will speed up or slow down the heat Change in each of this surrounding condition will speed up or slow down the heat Change in each of this surrounding condition will speed up or slow down the heat Change in each of this surrounding condition will speed up or slow down the heat rejection or gain.rejection or gain.rejection or gain.rejection or gain.

COMFORT ZONE FOR HUMAN BEINGS

What is the best temperature in which all will feel comfort?What is the best temperature in which all will feel comfort?What is the best temperature in which all will feel comfort?What is the best temperature in which all will feel comfort?

22222222----26.5 26.5 26.5 26.5 °°°°cccc

What is the best relative humidity which gives you comfort?What is the best relative humidity which gives you comfort?What is the best relative humidity which gives you comfort?What is the best relative humidity which gives you comfort?

30303030----70 %70 %70 %70 %

OUTSIDE AND INSIDE

A man in outdoorA man in outdoorA man in outdoorA man in outdoor---- using clothes to control the body temperatureusing clothes to control the body temperatureusing clothes to control the body temperatureusing clothes to control the body temperature

A man in indoorA man in indoorA man in indoorA man in indoor---- we can control his comfortwe can control his comfortwe can control his comfortwe can control his comfort

HowHowHowHow

By means of HVACBy means of HVACBy means of HVACBy means of HVAC

OPENING IN THE FIELD OF HVAC

� MarketingMarketingMarketingMarketing

� DesignDesignDesignDesign

� InstallationInstallationInstallationInstallation

� MaintenanceMaintenanceMaintenanceMaintenance

FUNDAMENTALS

The The The The purpose of air conditioning is to create a purpose of air conditioning is to create a purpose of air conditioning is to create a purpose of air conditioning is to create a room room room room climate comfortable climate comfortable climate comfortable climate comfortable

for for for for people. While people. While people. While people. While the temperature should be between the temperature should be between the temperature should be between the temperature should be between 20 20 20 20 and 26and 26and 26and 26°°°°C, a C, a C, a C, a

relative humidity between relative humidity between relative humidity between relative humidity between 30 30 30 30 and 65 % is permitted.and 65 % is permitted.and 65 % is permitted.and 65 % is permitted.

SENSIBLE HEAT (SH)

When a substance is heated and the temperature rises as the heat is added, the increase When a substance is heated and the temperature rises as the heat is added, the increase When a substance is heated and the temperature rises as the heat is added, the increase When a substance is heated and the temperature rises as the heat is added, the increase in heat is called sensible heat. Similarly , when heat is removed from a substance and in heat is called sensible heat. Similarly , when heat is removed from a substance and in heat is called sensible heat. Similarly , when heat is removed from a substance and in heat is called sensible heat. Similarly , when heat is removed from a substance and the temperature falls, the heat removed is called sensible heat. In this case the state the temperature falls, the heat removed is called sensible heat. In this case the state the temperature falls, the heat removed is called sensible heat. In this case the state the temperature falls, the heat removed is called sensible heat. In this case the state of substance is unchanged. of substance is unchanged. of substance is unchanged. of substance is unchanged. EgEgEgEg. The heat absorbed in heating of water . The heat absorbed in heating of water . The heat absorbed in heating of water . The heat absorbed in heating of water uptouptouptoupto the boiling the boiling the boiling the boiling temperature is the sensible heat.temperature is the sensible heat.temperature is the sensible heat.temperature is the sensible heat.

SH = weight x specific heat x temp. differenceSH = weight x specific heat x temp. differenceSH = weight x specific heat x temp. differenceSH = weight x specific heat x temp. difference

100kg potato have temperature is 25100kg potato have temperature is 25100kg potato have temperature is 25100kg potato have temperature is 25°°°°C. how much heat required to remove from C. how much heat required to remove from C. how much heat required to remove from C. how much heat required to remove from potato to reduce it temperature 5potato to reduce it temperature 5potato to reduce it temperature 5potato to reduce it temperature 5°°°°C.C.C.C.

Specific heat of potato = 0.86Specific heat of potato = 0.86Specific heat of potato = 0.86Specific heat of potato = 0.86

Weight = 100 kgWeight = 100 kgWeight = 100 kgWeight = 100 kg

Temp. differ. = 25Temp. differ. = 25Temp. differ. = 25Temp. differ. = 25----5 = 205 = 205 = 205 = 20

SH = 100x0.86x20 = 1720 k cal.SH = 100x0.86x20 = 1720 k cal.SH = 100x0.86x20 = 1720 k cal.SH = 100x0.86x20 = 1720 k cal.