Vishal Bhalla

Numerical Study of Solar Photovoltaic/Thermal (PV/T) Hybrid Collector Using Nanofluids

The commonly used methods to harness solar energy are solar thermal and solar photovoltaic (PV). A new category photovoltaic/thermal (PV/T) hybrid combines these two technologies, and achieves higher combined efficiency. The challenge is to keep the operating temperature of the PV low and at the same time not compromise on the temperature of the thermal cycle. Various designs of PV/T hybrids (both flat plate and concentrated) have already been proposed which utilize air or water to remove the heat from PV cells in order to enhance the overall efficiency of PV/T hybrid collector. Recent papers have showed that nanofluids can be used as an optical filter to filter the required wavelength range (equivalent to the band gap of the PV cell) from solar spectra. Thus, the heating of PV cells can be significantly reduced and higher overall efficiencies can be achieved using selective absorption by nanofluids. In this study, a new design of a PV/T hybrid collector was proposed and two nanofluid filters that can be used with Silicon (Si) PV cells were identified and corresponding thermal and overall efficiencies of PV/T hybrid collector were calculated.Copyright

Enhancing the efficiency of absorption refrigeration cycle by ‘seeding’ nanoparticles directly in the working fluid

The fossil fuel-driven electricity grid supplies space cooling especially in tropical/temperate climate regions. The timing of the peak load closely coincides with the peak of available solar irradiance. Therefore, solar-driven space cooling can reduce the peak loads in a smart grid. Solar-powered, direct absorption refrigeration cycles fit well. The efficiency of this cycle can be enhanced through the use of new, engineered materials. This study analyses a model of ammonia–water based absorption refrigeration cycle in which nanoparticles are directly ‘seeded’ in the working fluid itself. The model has been tested at various locations in India.

Solar Thermal Energy: Use of Volumetric Absorption in Domestic Applications

Solar thermal systems are one of the renewable energy systems used in the residential buildings for the heating purpose, and with these systems, the usage of non-renewable energy resources decreases. To improve the performance of solar collectors, engineers and scientists are regularly working on it. Direct absorption-based solar thermal collectors (DASTC) are kind of solar collectors in which the fluid can be heated directly (without any absorption surface). The present study deals with numerical model of direct absorption-based solar collector which can be used for residential purposes. The absorbed energy fraction, effect of the height, length of collector, and mass flow rate on the collector efficiency have been determined. The analysis shows that collector efficiency increases with the increase of mass flow rate when the height of the fluid in the collector is same and the efficiency of the collector deceases with the increase of channel length. Further, it has been observed that it is beneficial to use an optimum volume fraction of the nanoparticles in DASTC because at an optimum volume fraction, the collector achieved maximum efficiency.