Investigation On A Novel Cryogenic Heat Transfer Method Based On Natural Circulation Cooling And Cryogenic Heat Pipe

A novel heat transfer method of cryogenic heat transfer is proposed, which combines the cryogenic heat pipe (CHP) and natural circulation cooling (NCC) together. As an efficient heat transfer method, the cryogenic heat pipe (CHP) can transfer more heat within a small temperature difference, while the natural cooling circulation (NCC) can fleetly cool down an object in a large temperature range. The method takes advantages of the NCC and the CHP, and eliminates the disadvantage of the NCC for its low thermodynamic efficiency. Furthermore, it has also the merit of a self-feedback process, which makes the object come back to the objective temperature quickly.The experiments have been performed to verify the effective working temperature and maximum heating power. The effects of filling ratio and inclination angle on its heat transfer rate is experimentally investigated. For this self-made thermosyphon, the optimum filling ratio is about 0.185 and the optimum inclination angle to the horizon is about 50°. In the experiments, if the filling ratio is more or less, it is bad at the performance of heat transfer. So it is suggested that the filling ratio should be between 0.15 and 0.2. On the ground application, the inclination angle is important factor. In the paper, the performance of heat transfer is the best between 30° and 60°. So the thermosyphon should keep a certain inclination angle when it is working.The experiments have been performed to study the flow characteristics of small size pipe and a novel cryogenic heat transfer method based on natural circulation cooling and cryogenic heat pipe. By the software of FLUENT, some numericalsimulations have been done only about the natural circulation cooling. The results are compared with that simply cooled by a NCC or a CHP, which show the potential for further applications. It is proved that only CHP or NCC is not enough to transfer more heat during the total process of cooling. In the compound system, the natural circulation has more important effect during cooling process and the cryogenic heat pipe has more important effect during steady working process. They both keep the object in the cryogenic condition. They affect each other and make the other work in the better condition. The working temperature of thermosyphon is decided by the working fluid. If the cooling temperature is higher than the working temperature, the thermosyphon can't work. During the different condition, the natural circulation and thermosyphon should be changed in the compound system.