Comparison of Solar Sorption Cooling Systems Using TRNSYS Software

Rebecca SelwynMarie-Esther GuillermDr Hind Saidani-Scott

Outline

•Traditional Refrigeration•Problems with Vapour Compression Cycles•Sorption Cycles

Introduction

•Aims•Context•System Layout•Comparisons

TRNSYS Simulation

•Results•Discussion

Conclusions

•Improving the SimulationNext Steps

Traditional Refrigeration• Vapour

compression cycle• High efficiency (COP

>3)

• Replace compressor with sorption cycle

Heat based compression instead of electric compressor

Condenser

Expansion Valve

Evaporator

Compressor

Qc

W

Qe

Vapour Compression vs. Sorption Cycles: Refrigerant

Traditional Refrigerants• Ozone depletion• Montreal Protocol to

eliminate use of traditional refrigerants

Need to find suitable replacement refrigerants

Sorption Refrigerants• Sorbent-refrigerant

working pair• Range of working pairs

give range of characteristics

Vapour Compression vs. Sorption Cycles: Compression

Sorption Generator• Pressure increased

through heat cycle• Requires low grade heat

input (>170°C), e.g. Solar thermal or waste industrial heat

Electric Compressor• Climate change• Kyoto protocol to reduce

greenhouse gas emissions

Need to find alternatives to traditional electric compressors

Outline

•Traditional Refrigeration•Problems with Vapour Compression Cycles•Sorption Cycles

Introduction

•Aims•Context•System Layout•Comparisons

TRNSYS Simulation

•Results•Discussion

Conclusions

•Improving the SimulationNext Steps

TRNSYS Simulation: Aims

Simulation of Sorption

Cooling Systems

Connect pre-defined

components together to model

simple system

Create adsorption chiller component

in Matlab

Use real weather data for heat

source

Compare adsorption and

absorption under identical

conditions

TRNSYS Simulation: Context

Malaysian weather dataHuman cooling:– Air conditioned office

environment: ‘Seated, light work, typing’

– PCs, lighting, windows

Food cooling:– Refrigerated storage– Heats of respiration of

fruit and veg.

2m

10m10m

TRNSYS Simulation: System Layout

Weather Data

Solar PanelSorption System

Cooling Load

TRNSYS Simulation: Comparisons

Cooling System• Absorption– LiBr-water

• Adsorption– Activated carbon-

methanol– Zeolite-methanol– Silica gel-water

Cooling Application• Human cooling (air

conditioning)• Food cooling

(refrigeration)

Outline

•Traditional Refrigeration•Problems with Vapour Compression Cycles•Sorption Cycles

Introduction

•Aims•Context•System Layout•Comparisons

TRNSYS Simulation

•Results•Discussion

Conclusions

•Improving the SimulationNext Steps

Results: Human Cooling

Sorbent volume (m3) COP0

0.10.20.30.40.50.60.70.80.9

Human Cooling

Zeolite-methanol Silica gel-water Activated carbon-methanol LiBr-water

Results: Food Cooling

Sorbent volume (m3) COP0

0.10.20.30.40.50.60.70.80.9

Food Cooling

Zeolite-methanol Silica gel-water Activated carbon-methanol LiBr-water

Discussion

• Ratio of COP to required adsorbent volume

• For freezing use activated carbon-methanol

Human cooling Food coolingZeolite-methanol 3.40 3.05Silica gel-water 3.35 4.30Activated carbon-methanol 2.84 3.33

Outline

•Traditional Refrigeration•Problems with Vapour Compression Cycles•Sorption Cycles

Introduction

•Aims•Context•System Layout•Comparisons

TRNSYS Simulation

•Results•Discussion

Conclusions

•Improving the SimulationNext Steps

Next Steps

Extending the simulation scope

Effect of non-equilibrium

conditions in sorption process

Effect of different climates

Ionic liquids as possible sorbents

Thank You

Any Questions?