Condensation characteristics of a loop thermosyphon heat exchanger for a low temperature Stirling engine

Abstract

In the Stirling engine that utilizes waste heat, it is common to directly heat the working gas from high-temperature exhaust gas. However, this method results in a high temperature in the expansion space, leading to deterioration in reliability of engine components. To solve this problem, a low temperature Stirling engine was devised using a loop-type thermosyphon heat exchanger, which enables heat transfer by evaporating and condensing refrigerant between high-temperature exhaust gas and working gas. By using this method, the working gas can be indirectly heated through the low-temperature refrigerant, resulting in lower temperature in the expansion space and improved reliability. This study evaluated the condensation performance when applying a shell-and-tube heat exchanger to the heater. The results clarified the influence of the refrigerant amount on the heat transfer rate of the heater.