An experimental study of a carbon dioxide-filled thermosyphon for acquisition of low-temperature waste energy

The aim of this work is to assess the possibility and usefulness of accessing low-temperature energy using a carbon dioxide-filled two-phase thermosyphon. Various parameters, such as working fluid filling ratio, coolant mass flow rate, and temperature difference between evaporator and condenser, affect the heat transfer of thermosyphon system. In order to investigate the performance of thermosyphon system, we monitored the temperature distribution along the thermosyphon and measured input heat to evaporator section and output heat from condenser, as well. The results show that the heat transfer rate of this system increases with increasing mass flow rate and bath temperature (waste energy temperature). The results also show that the overall heat transfer coefficient increases with increasing coolant mass flow rate but decreases with increasing the temperature difference between bath and condenser section. The reason for this decrease is partly due to the decreasing of the enthalpy of vaporization of the carbon dioxide with increasing temperature. Copyright (C) 2009 John Wiley & Sons, Ltd.