Grid-shape electrical circuit assembled with resistance temperature detectors for multipoint temperature measurement of solid oxide fuel cells

A multipoint temperature measurement technique using a grid-shape sensor array constructed with resistance temperature detectors (RTDs) is proposed to reduce the number of cables for measurement compared with the conventional approaches such as thermocouples. DC voltage is applied between a set of nodes in the circuit, and the voltage of the other selected nodes at the outer perimeter and the response current are measured as outputs. Theoretical expressions to correlate these outputs with the resistance of the RTDs are derived to obtain the temperature of the RTDs. The feasibility of the proposed method is examined by applying the method to temperature measurement of a flat plate under uniform, linear, and radial temperature distributions near room temperature. The accuracy estimated by comparing the results obtained by this proposed method with those obtained by conventional thermocouple measurement is confirmed within 0.51 K in the temperature range tested. Moreover, the proposed circuit was established to profile the temperature of a practical-size solid oxide fuel cell (SOFC) at its operating temperatures of 920-1000 K with and without power generation. Through the experiments conducted, the proposed technique is proven to be feasible for multipoint temperature measurement of operating SOFCs.