The irreversible two-stage TEG consists of a top stage with m1h thermocouples and a bottom stage with m1c
thermocouples. Each thermocouple is composed of a P-type and an N-type semiconductor legs. The Joulean loss generates
an internal heat I2R1, where R1 is the total internal electrical resistance of the thermocouple and I is the working electrical
current generating from the thermocouple. The conduction heat losses are K1 .Th1