Zu-Guo Shen

Performance comparison investigation on solar photovoltaic-thermoelectric generation and solar photovoltaic-thermoelectric cooling hybrid systems under different conditions

ABSTRACT The performance of solar photovoltaic-thermoelectric generation hybrid system (PV-TGS) and solar photovoltaic-thermoelectric cooling hybrid system (PV-TCS) under different conditions were theoretically analysed and compared. To test the practicality of these two hybrid systems, the performance of stand-alone PV system was also studied. The results show that PV-TGS and PV-TCS in most cases will result in the system with a better performance than stand-alone PV system. The advantage of PV-TGS is emphasised in total output power and conversion efficiency which is even poorer in PV-TCS than that in stand-alone PV system at the ambient wind speed uw being below 3 m/s. However, PV-TCS has obvious advantage on lowering the temperature of PV cell. There is an obvious increase in tendency on the performance of PV-TGS and PV-TCS when the cooling capacity of two hybrid systems varies from around 0.06 to 0.3 W/K. And it is also proved that not just a-Si in PV-TGS can produce a better performance than the stand-alone PV system alone at most cases.

Experimental Study on The Effect of Wind on Heat Losses from a Fully Open Cylindrical Cavity with only Bottom Wall Heated

An experimental study using electrical heating method has been performed to explore the impact of wind speed, wind incidence angle as well as cavity inclination on the heat losses from a fully open cylindrical cavity with only bottom wall heated at constant heat flux. The cavity under different inclinations is subjected to four different wind speeds of 1.15, 1.84, 2.94, 5.69 m/s, and wind incidence angles from 0° (wind blowing parallel to cavity aperture plane) to 90° (wind blowing vertically to cavity aperture plane) at intervals of 30°. Results reveal that, the average temperature of cavity wall decreases with increasing wind speed and wind incidence angle. The combined convection heat loss increases obviously with the increase of wind speed, while the radiation and conduction heat losses decrease for all wind incidence angles. The variations of convection heat loss with the cavity inclination at constant heat flux boundary condition are quite different from that at constant wall temperature boundary condition. The combined free-forced convection heat loss Nusselt number Nuc is more sensitive to the wind speed and wind incidence angle in comparison with the radiation heat loss Nusselt number Nur. In addition, new correlations of Nusselt numbers have been developed to estimate the convection heat loss and radiation heat loss due to the environmental wind.