Heat and Mass Transfer
Omid Ahmadi; Sahand Majidi; Pooyan Hashemi Tari
Abstract
Phase Change Materials (PCMs) are known to be capable of storing a substantial amount of energy in relatively low volume. Also, since the phase change process occurs in a nearly constant temperature, PCMs are suitable to be used as storage units. The present study focuses on the effect of Heat Transfer ...
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Phase Change Materials (PCMs) are known to be capable of storing a substantial amount of energy in relatively low volume. Also, since the phase change process occurs in a nearly constant temperature, PCMs are suitable to be used as storage units. The present study focuses on the effect of Heat Transfer Fluid (HTF) flow parameters on heat transfer and melting process of PCM. The numerical results are validated against available experimental data. Then, the numerical study is extended to investigate the impacts of HTF flow parameters such as inlet temperature and mass flow rate. According to the obtained numerical results, the overall performance of the system is enhanced by increasing the inlet parameters of the HTF flow. In addition, the exergy analysis indicated that the stored exergy increases with increasing flow rate and inlet temperature of HTF. On the other hand, the exergy efficiency does not increase monotonically, but it reaches its maximum value in intermediate values of inlet flow rate and temperature.
Heat and Mass Transfer
Sidharth Sudhansu Chakrabarti; Akash Pandey; Pratik Dhage
Abstract
Solar energy is the highly recognized energy source, capable of fulfilling the world’s future energy demands. The solar photovoltaic technology involves the unmediated transformation of sunlight into electricity. A little fraction is converted into electricity and the remaining gets exhausted as ...
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Solar energy is the highly recognized energy source, capable of fulfilling the world’s future energy demands. The solar photovoltaic technology involves the unmediated transformation of sunlight into electricity. A little fraction is converted into electricity and the remaining gets exhausted as unused heat. This results in an increase in the operating temperature of the PV Panel. The conversion efficiency and the life span of the photovoltaic panel are affected by an increase in working temperature. Hence, an appropriate cooling technique is essentially required for maintaining the operating temperature of the module within the limits prescribed so as to obtain higher electrical yield and increased lifespan. The objective of this paper is to present a summary of the various cooling techniques used to enhance the performance of PV panels, namely air cooling - free and forced, water spray cooling, cooling by phase change materials, heat pipe cooling, liquid immersion cooling and forced water circulation. Several research articles are reviewed and classified on the basis of technology used for the thermal management of PV modules. The paper also investigates one of the passive evaporative cooling technique to control the temperature rise of the PV module and enhancement in efficiency. Around 12oC reduction in PV panel temperature under maximum insolation and 7.7 % increase in average electric power generation efficiency was observed under this technique.
