Economic, thermal analysis and optimizing of a novel hybrid fuel cell and two-stage thermoelectric device for waste heat-recovery applications

The role of any fuel cell is direct electricity-generation using electrochemical reaction. However, wasted heat is an unavoidable side-product of any fuel cell. Thermoelectric is another electricity generator producing electricity directly from a source of heat. Hence, this is a potential opportunity to recover the waste heat of the fuel cell by thermoelectric generator meaning higher overall performance of the system. This research proposes and optimizes a novel hybrid fuel cell and two-stage thermoelectric generator to catch the mentioned goal of the research. In this hybrid-system, the serpentine channels of the fuel-cell are directly in contact with ceramic layer of a two-stage thermoelectric generator. The proposed configuration is investigated using a validated 3D-finite-element-method. A comprehensive parametric analysis is provided to optimize the system. The results reveal a great performance for the suggested two-stage TEG configuration when the high-temperature skutterudites and low-temperature bismuth tellurides are employed in the high-temperature and the low-temperature stage respectively. The overall-output-power enhances 2.73-fold in the optimized configuration. Increasing the overall thickness enhances output power, with a notable 233 % increase, when h_t goes from 1 to 4. A remarkable 209 % growth is shown when the number of thermocouples in the low temperature stage increases from 36 to 144.