UWE Bristol Engineering showcase 2015
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MUHAMMAD HUSSAIN<br />
BENG MECHANICAL ENGINEERING<br />
Investigation and Feasibility of a PV-T Solar-Powered Absorption Cooling<br />
System with a Dehumidifying Wheel in Dubai; (UAE)<br />
Introduction<br />
The increase in electricity consumption particularly during summer because of the wide-ranging use of air-conditioning systems<br />
and the risk of global energy shortage augmented the attention of scientists towards solar energy in the recent years. There is<br />
13% increase of electricity consumption per capita in the United Arab Emirates (UAE) from 8275.67 kWh in 1992 to 9388.58<br />
kWh in 2011 (World Bank 2014). The annual global irradiance stated by GeoModel Solar Energy (2011) is 1800kWh/m 2 .<br />
Though, utilizing the solar energy to constrain cooling processes is very striking especially in Dubai, United Arab Emirates where<br />
the solar radiation is at its peak. The best way of using solar radiation is to convert it into thermal and electrical energy passing<br />
through Photovoltaic-thermal solar collector and use it to drive thermal cooling cycle that is Absorption cooling and a<br />
dehumidifying system. The passive cooling uses sources of renewable energy such as sun’s radiation in order to provide the<br />
cooling and other household needs for example lightning and ventilation.<br />
Results & Analysis<br />
The results achieved for the<br />
performance of absorption cooling<br />
system through mass and energy<br />
balance equations. The moisture load<br />
for dehumidification is calculated for a<br />
building. The absorbent used is Lithiumbromide<br />
(Li-Br) based on its case study<br />
while considering the control strategies<br />
to prevent crystallisation. All<br />
calculations and results were created<br />
on the basis of solar radiation in Dubai .<br />
Variables Values Units<br />
Qevaporator 325 kW<br />
Qgenerator 395.36 kW<br />
Qcondenser 351.6 kW<br />
Qabsorber 348.55 kW<br />
Heat exchanger solution 131.46 kW<br />
Pump work<br />
0.0095<br />
3 kW<br />
COP<br />
0.8220<br />
35613 -<br />
Area of PV-T solar collector 2179 m^2<br />
Power of the system 326.9 kWp<br />
Recovery period 7.98 years<br />
Efficiency/COP<br />
1.6<br />
1.4<br />
1.2<br />
1<br />
0.8<br />
0.6<br />
0.4<br />
0.2<br />
0<br />
Thermal Regeneration Evaluation<br />
50 55 60 65 70 75 80 85 90 95<br />
Heating Water Setpoint (°C )<br />
Thermal COP<br />
Solar Fraction<br />
Regenerator<br />
Thermal COP<br />
Collector<br />
Efficiency<br />
Average Total<br />
Cooling<br />
Average Latent<br />
Cooling<br />
Final Designing Evaluation<br />
A detailed description of PV-T solar collector is retrieved with its drawbacks and solutions. The cooling energy is assumed as 325kW and all energy and mass<br />
equations of generator, absorber, evaporator and condenser are calculated on its basis. The area of a solar collector is obtained to be 2179m 2 and a PV phase<br />
power output of 326.9kWp. The energy at generator is achieved 395.36kW which resulted system’s Coefficient of Performance as 0.822. The heat source of Li-Br is<br />
reviewed at different temperatures and its problems are explained with a relevant solution. The cooling load is also calculated by assuming the size of building and<br />
using different strategies of shading factors to windows, walls and roof. The solar declination angle is 17.69° with a total cooling load 14.025kW and total<br />
dehumidified air is obtained to be 132.9m 3 /min. The internal concentration is also stated at different evaporator temperature which helps to classify the<br />
behaviour of a solution and its controlled limit. Also the evaluation of absorption cooling system with thermal regeneration is explained and concludes that<br />
increasing efficiency leads to the reduction in thermal COP and solar fraction but also increasing the average cooling load and regenerator thermal efficiency.<br />
Project Supervisor<br />
Dr. ARUNA PALIPANA<br />
Project Aims<br />
To overview solar PV-T assisted absorption cooling<br />
system with a desiccant dehumidifying wheel in<br />
order to have a maximum cooling with minimum<br />
energy consumption.<br />
Project Objectives<br />
• To investigate and obtain results of energy<br />
transferring through Photovoltaic-thermal solar<br />
collector.<br />
• To analyze absorption cooling system in Dubai<br />
based on its results of performance assisted with a<br />
thermal phase of collector.<br />
• Obtain the moisture load and reduce the level of<br />
humiidity through desiccant dehumidifier assisted<br />
by a PV phase of solar collector.<br />
• Obtain the economic feasibility and pay-back<br />
period of a complete cooling & dehumidifying<br />
system.<br />
Project Conclusion<br />
The investigation and feasibility of a Solar PV-T<br />
Absorption Cooling system with a dehumidifying<br />
wheel conclude that this system is an environmental<br />
responsive operation ideology with zero energy<br />
consumption and a COP of 0.822 which is an effective<br />
value of a cooling system. The concept of PV-T solar<br />
collector can help generate two forms of energy<br />
through a single unit with a backup strategy of cooling<br />
even at night. The solar cooling system does require<br />
more space but the payback value makes it stronger<br />
and a valuable appliance. Overall, the system based<br />
on its results, theoretical research and final designing<br />
concept proves that it can be used practically at both<br />
small and large-scale. Therefore, it is practicable in<br />
Dubai; United Arab Emirates weather conditions and<br />
an intensive effort needs to be planned to publicise<br />
this green technology in market.
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