Passive Condensers

The condensation phenomenon plays an important role in the heat transfer process in the chemical and power industry, including nuclear power plants. Condensers that are based on natural forces are called passive condensers and they do not require pumps or blower to move fluid. Examples of passive condensers include passive condenser systems in nuclear reactor safety systems, closed loop heat pipes, passive condenser for harvesting dew from surrounding humid air and passive refrigeration systems. In nuclear reactors, there is a greater emphasis on replacing the active systems with passive systems in order to improve the reliability of operation and safety. Heat pipes with passive condensers have been developed to transport high heat flux from electronic devices. In practical operations of the passive condensers, small amounts of non-condensable gas may exist in working vapors due to characteristics of the system or dissolution of working vapors. It is well known that the presence of non-condensable gases in a vapor can greatly reduce the performance of condensers. This is because of the fact that the presence of non-condensable gas lowers the partial pressure of the vapor, thus reducing the saturation temperature at which condensation occurs. In this chapter, state-of-the art in passive condensers topics are covered including various types of passive condensers designs and their applications. The theory of passive condensation, condensation models, and experimental work on the passive condensers is presented. Practical heat transfer relations applicable to various passive condensers are presented and discussed.