Multijunction thermophotovoltaic cell for efficient power generation out of the waste heat in solid oxide fuel cell

Multijunction thermophotovoltaic (MTPV) cells, with integrated back surface reflector, are combined in solid oxide fuel cells (SOFCs) as a highly efficient novel hybrid system to exploit waste heat. The intellectual merit of using MTPV cell is verified analytically in terms of power output density and efficiency of the TPV cell, SOFC and designed hybrid system. Optimum performance analysis of the hybrid system is obtained based on the ratio of the emitter area to the surface area of the contact electrode, back surface reflectivity, the band gaps, as well as the number of junctions. Optimal key parameters of the systems were suggested at the maximum power density. Use of MTPV eliminated the historical tradeoff between efficiency and power density of TPV converters to provide practically-viable high performance TPV systems. The proposed model significantly increases the employment of the waste heat produced in SOFCs for conversion to electricity. Results showed that, the innovative use of MTPV in the hybrid system, leads to a more efficient hybrid system than other SOFC-based ones because of obtaining higher efficiency and power density.