Combined Thermosyphon and Thermoelectric Modules for Power Generation From Salinity Gradient Solar Ponds
Abstract
Salinity-gradient solar ponds can collect and store solar heat at temperatures up to 80oC. They can thus be a renewable source of heat for generation of electricity using thermoelectric modules capable of operating at temperature differences in the range 30 oC to 50 oC. The temperature difference between the lower convective zone and the upper convective zone is applied across the hot and cold surfaces of the thermoelectric modules. A system in which heat from the lower zone is transferred to the hot surface of the thermoelectric modules using gravity-assisted heat pipes as thermosyphons has been investigated experimentally. The modules are located so that their cold surfaces are in contact with the upper convective zone of the solar pond. The pipe surfaces are insulated in the region they pass through the gradient layer of the solar pond. Results for power output of the proposed combination of thermosyphon and thermoelectric cells operating over temperature differences existing in solar ponds are reported. The prospects for using solar pond – thermoelectric power generation for remote area power supply system are discussed. A potential advantage of such a system is its ability to continue to provide useful power output at night time or on cloudy days because of the thermal storage capability of the solar pond. The proposed combined thermosyphon and thermoelectric system was installed in a small experimental solar pond at RMIT campus in Bundoora and electric power was generated utilizing the temperature difference between the top and the bottom of the pond. Research results in the present work indicate that there is a significant potential for electric power generation from small solar ponds through a simple and passive device incorporating thermosyphons and thermoelectric cells.