Numerical and experimental study of a non-frosting thermoelectric generation device for low temperature waste heat recovery

Abstract

Liquefied natural gas (LNG) has great potential for power generation using thermoelectric generators (TEG) due to the large amount of cold energy released during LNG gasification, but frosting is a major issue which slows the heat transfer between the TEG and the environment and reduces the power generation efficiency. This study describes a non-frosting cryogenic thermoelectric generator for cold energy recovery. This device uses natural gas vapor on the hot side of the TEG to avoid frosting caused by direct contact of the TEG with air. The device characteristics were modeled using a thermodynamic analysis with the predictions verified by experiments to predict the output characteristics. The results show an optimal channel length for the selected design conditions that maximizes the power generation. Increasing the flow rate and enhancing the heat transfer on the hot side significantly increases the power output. For the design conditions of 1000 Nm3/h gasification capacity and 0.4 MPa working pressure, the optimum channel length is 9.8 m with 350 pairs of thermoelectric modules that gives the maximum power generation of 593.94 W with a 1.36% efficiency.