Solar-Powered Cooling, Dehumidification and Air Conditioning

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 1

SOLAR-POWERED COOLING, DEHUMIDIFICATION

AND AIR CONDITIONING

Prof. Gershon Grossman

Faculty of Mechanical Engineering

Technion, Israel Institute of Technology

Haifa 32000, ISRAEL

November 2010

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 2

Demand for Air Conditioning

in the World is on the rise…

• Climate change and Global Warming

• Increased standard of living

• Demand for comfort • European countries with no A/C tradition: “12 participants

(national energy agencies, manufacturing experts, university

labs, electric utilities) from 8 countries including the EU

manufacturer’s association EUROVENT gathered to identify

suitable measures to transform the Central Air Conditioning

market in the direction of Energy Efficiency” (EU Report, 2003)

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 3

Demand for A/C associated with

increased demand for primary energy…

• Solar Cooling can Alleviate the Problem

• Closed-cycle systems: Absorption,

Adsorption, Jet-cooling….

• Open-cycle systems: Liquid desiccant,

Solid sorption

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Solar Cooling System

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 5

Solar Cooling/ Air Conditioning

TA TH

QH

QL QA1

QA2

TA TL

Heat

Engine

Heat

Pump

W

• Heat Pump driven by

Heat Engine

• Absorption/Adsorption

Heat Pump

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 6

Chemical Heat Pump Principle

NH3

H2O

+NH3 NH3

H2O

+NH3

Tpure = Tsolution

Ppure > Psolution

Tpure < Tsolution

Ppure = Psolution

Tsolution-Tpure=Temperature Lift

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 7

Absorption Heat Pump Principle

Desorber

Absorber

QM2

QH

Evaporator

Condenser

Comp

QL

QM1

W

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 8

Single-Effect LiBr-H2O Absorption Chiller

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 9

Prototype 50 TR (175 kW) Solar

Absorption Cooling System, Tadiran ASD

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 10

Tadiran ASD Solar Cooling Project

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 11

200 TR (700 kW) Solar Absorption Cooling

System at Tel-Hashomer Hospital, Israel

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 12

Absorption Working Fluid Pairs

• NH3-H2O

• H2O-LiBr

• Other absorbents for NH3 and H2O

• Organic absorbents for CFC/HCFC

• Ternary mixtures

• Additives – anti-corrosion, enhanced heat transfer

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 13

Absorption Systems –

first cooling machines in History

• Chemical Heat Pumps – as early as 18th century

• First continuously operating refrigerators – Edmond and

Ferdinand Carrè ~1860

• Gas-fired NH3-H2O domestic refrigerators up till ww2

• Large-scale H2O-LiBr chillers powered by waste heat and

solar

• Multi-effect gas-fired chillers for A/C ~1980’s and on

• Domestic NH3-H2O heat pump development

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 14

Absorption Multi-Staging

• Staging required

to benefit from hi-

temp heat source

• Double-effect

chillers: Series

and parallel

connections

•Triple-effect

systems

•Cascading

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 15

Multi-Staging allows improved performance

with high heat source temperatures

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

50 100 150 200 250

Heat Supply Temperature (oC)

CO

P

Carnot

1-effect

2-effect

3-effect

Chilled Water: 7.0oC

Cooling Water: 30.0oC

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 16

Research Needs

• Advanced cycles

• Advanced fluids

• Heat and mass transfer in absorption/desorption

• System simulation

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 17

ABSIM Modular Simulation Tool for Absorption and

other Thermal Systems

• User-oriented, modular and flexible

• Evaluate different cycle configurations and

working fluids

• Evaluate system performance in off-design

conditions

• Perform preliminary design optimization

• Check control strategies

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 18

ABSIM - Program Structure

S OLVER 1. Condition set of equations 2. App ly constraints 3. Solve system of equations

MAIN PRO GRAM 1. Interp ret inp ut 2. Form variable vector 3. Link units and form equations martix 4. Normalize 5. Activate solver

UNIT SUBRO UTINES 1. Absorber 2. Desorber 3. Heat exchr 4. Condenser 5. Evap orator 6. Valve 7. Mixer 8. Splitter 9. Rectifier 10. Analyzer 11. Compressor 12. Pump

PRO PERTY DATABAS E

OUTPUT

USER INPUT

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 19

Desiccant System Principle

Air Desiccant

QH

QL

Two types of Desiccants

• Adsorbent

• Absorbent

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 20

Liquid Desiccant vs. Absorption

Air LiCl-H2O

QH

LiBr-H2O

QH

Evap

Cond

QL QL

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 21

Cooling by controlled drying and

wetting

Dehumidifier

1

Controlled

wetting

Ambient Temp

3 2

4

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 22

Comfort

Zone

Cooling by controlled drying

and wetting

50%

70%

Saturation

100%

KgDryAir

OKgHW 2

)(0 CT

4

2

3

Desiccant

Dehumidifica

tion

Ambient HX

Wetting

1

6

5 Indirect Contact

Cooling

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 23

Schematic Description of Desiccant System

Air/Air H.X.

Fresh Air

Outlet

AirBlower

Solution Pump

Hot-Water

Pump

Water/Solution H.X.

Hot Water

From Storage

Tankto Absorber

to Storage

Tank

Drain

12

34

1h

56

7

8 9

Desorber

Fresh Air

Supply

Air

Absorber

Blower

Solution Pump

Cold-Water

Pump

Water/Solution H.X.

Cold Water

From Cooling

Tower

to Cooling

Tower

Drain

1c

10 11

1213

14

15

16

C.M.1

C.M.2

10c 10h

1c

SV

to

Solution

Storage

Tank

to Solution Storage Tank

From Solution

Storage Tank

Splitter

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 24

20-kW Solar Liquid Desiccant System at

Technion, Haifa, Israel

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 25

Control Unit - View of Computer Screen

Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 26

Solar Collector Field

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The End

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