Professor Kim Choon NG, Mechanical Engineering, National University of Singapore, and Visiting Professor Water Desalination and Reuse Centre, KAUST, SA Email: mpengkc@nus.edu.sg Kim.ng@kaust.edu.sa

Solar powered adsorption cooling cum desalination

Adsorption-triggered-evaporation Desorption-activated-condensation

25-33°C

28-36°C

55-85°C, from Solaror waste heat

45-75°C25-30°C28-33°C

7-28°C12-33°C

Mesoporous adsorbent

SiO3.nH2 O , 800m2/g

Cooling power, Tchilled = 7-20°C, 25- 32 Rtons/tonne

Potable water TDS <10ppm, pH =7.3,±0.15 to 12 m3/tonne.day

Advantages:-Produce two useful effects with low-temperature heat input,-low specific energy (electric) consumption (1.38kWh/m3), -no major moving part, inexpensive materials for construction

• The daily average radiation in Thuwal (KAUST) is about 22 MJ/m2.day (latitude λ=22o , sunshine hours from 9 to 13 h/day)

• Estimated thermal rating is 1300 kWh/m 2.year, as compared with 925 kWh/m 2.year @ 65o C in Singapore .

• Recommend to use tube collectors because (i) it is easy to handle, (ii) it reduces the dust accumulation – dust particles will slide over the tube curvature whilst those accumulated on top could be blown over by strong wind.

Provide shading that reduces heat stress in green houses.

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Exhaust Gas

Why Co-Generation ?

Electricity (- max at 1.3 MW)

Steam (4800 kg/h)

• Cooling (7o C and 15-18

0C)• Water

(5 l/m2 .day)

Electricity from grid ( )42.0th

“Kettle” Boiler (8 bar)

Electrically-operated decicant dehumidifier

Gas Turbines x 2 units of 700 kW

Temperature cascaded utilization of exhaust energy with AB_AD chillers

Waste heat operated boiler (8 bar)

Steam driven AB/AD chillers

375 to 500oC

125o C

Primary fuel, (Town gas)

TriGen EUF =0.85- Thermally-driven design

Conventional EUF=0.52

DARI’s energy needs

Conventional approach

Co-generation cum solar

Primary fuel

diesel

electricity

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Grid of KAUST

Electric chillers (400 Rtons)

CWS =7 C

Gas Turbines (2x 700 kW)

360 kW1000 to 1200 kW

Steam(177 C, 8.3 bar)

AB chillers (COP 0.9 to 1.1) giving 800 to 1000 Rtons

AD Chillers (COP =0.5 to 0.65) giving 120 to 150 Rtons

500-600 kW for use in DARI

CWS = 9-10 C

CWS = 14 to 18 CWater production75 m /day

Further waste heat recovery

50-60 kW 20 to 25 kW

Seawater Cooling Towers (1200 Rtons)

40 – 55 kW

Exhaust leaving at < 125 C

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Sea Water Tank

Pre-treatment sea water tank

Sea water feeding line

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Reactor Bed Condensate drainage

Collection tank

Release Valve

Condenser

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Pretreatment

tank

Hot water

storage Waste heat recovery

from exhaust Fresh water

storage

Post treatme n t

tank

Sea water

Silo-type adsorber-desorber beds

Condenser and evaporator Cooling water system

valves

E x haust gas

2 0 0 to 25 0 C

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Reaction bed tower

Evaporator

Condenser

Purified water

storage tank Reaction bed tower

1

2 3

4

5

d d

H

Can the AD cycle scale to a commercial size ? – to work closely with industry partners of KAUST

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