Search Results

It is already well known that Loop Heat Pipes (LHPs) are able to transport heat over long distances, through flexible, small diameter tubes and against high gravitational heads. The existing experience of the conventional Heat Pipe history says that during the time some amount of non condensable gases (NCG) can be generated inside the closed system with the working fluid inside. It was shown in many previous publications how sensitive conventional heat pipes with composite wicks are on the presence of NCG. In spite LHPs are already widely applied in spacecraft, the NCG issue was not studied yet. The paper describes the work aimed at LHP operation study when NCG are injected. The experimental study of the LHP operation was performed. The LHP response on NCG injection with some increments was monitored in order to register any changes of the LHP performance. The End of Life (EOL) NCG amount in the ammonia LHP was calculated. The way of theoretical analysis is discussed in the paper.

Loop Heat Pipes have been shown to be reliable, self-starting, high capacity heat transport devices which offer significant performance improvements over conventional heat pipes. They are also capable of both constant and variable conductance operation, providing both temperature control and heat transport functions. Two different Loop Heat Pipes were tested to characterize their temperature control capabilities. Operation in both a passive, autoregulating mode and an active control mode were investigated. The test results demonstrate that temperature regulation in each mode is attainable. The effects of the operational environment on temperature control characteristics were found to be important and are discussed.