Investigation into topping cycle: Thermal efficiency with and without presence of thermoelectric generator

Thermoelectric power generation due to solar heating is a current interest in green energy research. One of the applications of the thermoelectric power generator is involved with the topping cycle, in which the thermoelectric generators were placed on the heat collector elements of a conventional solar concentration power plant. Although the topping cycle is practical and easy to operate, the efficiency of the thermal system with and without thermoelectric generator needs to be examined. In the present study, thermal efficiency of the topping cycle is analyzed and compared with its counterpart without the presence of the thermoelectric elements. Thermodynamic analysis for the efficiency of both the systems with and without thermoelectric generator is presented. The fluid flow and heat transfer in a tube with presence of thermoelectric elements resembling the solar heating system incorporated in the topping cycle are simulated numerically. It is found that, for a certain combination of operating and thermoelectric device parameters, thermal efficiency of the topping cycle becomes slightly higher than that of the same system without the presence of the thermoelectric generators.

► The overall efficiency ratio is introduced to assess the performance.
► Increasing the solar radiation reduces the overall efficiency ratio.
► Outer surface heat transfer coefficient reduces the overall efficiency ratio.
► The inner wall heat transfer coefficient enhances the overall efficiency ratio.
► The overall efficiency ratio increases with increasing working fluid temperature.