This relates to thermal diode. Thermal diode is  used for a device which causes heat to flow preferentially in one direction. This refer to one-way-heat flow and hence acts as rectifier. Electrical power is generated proportional to thermal gradient or difference in heat flux. This can be used a) as a heat engine which converts a heat difference directly into electric power, b) as a heat engine working backwards as a refrigerator and c) as a heat pipe which will only allow heat to flow from the evaporator to the condenser.

More details: https://en.wikipedia.org/wiki/Thermal_diode

Further you can refer an article "Thermal Diode: Rectification of Heat Flux" by Li et al.

AR Reddy: thank you sir,

the component rectifier is feasible to sustain the high heat carrying capacity for larger application such as defense or aeronautical application.