Development And Investigation Of Heat Transfer Performance Of Concentric Annular Heat Pipe Array

With the development of heat pipe technology, it has been widely used in spacecraftthermal control, electronic cooling, nuclear reactor control, and various domesticapplications due to their excellent thermal conductivity and flexible shape. In China, even allover the world, the reason why the mass of Low-grade waste heat cannot be utilizedeffectively is the lack of useful technology. And meanwhile, Low grade waste heat is theavailable approach to deal with the energy crisis. Therefore, an annular thermosyphon arrayhas been proposed and developed to solve this problem. This device consists of severalevaporator tubes that form a closed container with the annular are of the horizontal tube. Thisunique structure don’t only enhances the condensation heat transfer coefficient, but alsoincreases the condensing area. Heat recovery equipment with various capacities and formscan be assembled utilizing the heat pipe array. By testing and analyzing the temperaturedistribution on the wall of tubes, the heat transfer performance of the heat pipe array wasevaluated in various conditions.The theories of heat pipe have been introduced in the very beginning of this workespecially the mechanism of heat transfer, phase-change phenomena and fluid. The heattransfer limitations and the equivalent conductivity of the heat pipes are studied and analyzed.The experimental testing platform, testing means and process have been proposedand set up to measure its heat transfer performance especially for this developed device.Based on the theory of thermosyphon, a series of experimental studies were carried outon the property, including its isothermal performance, the performance of thermosyphonsurface temperature’s fluctuation, the operation temperature and obliquity. It revealsthat the maximum heat transport increases with the augment of the operationtemperature, evaporation length and condensation area, but showing the first growthafter the decline with increasing inclination and with the increase of the plate on the lawof growth dropped after the first. Eventually, the experimental data showed that theoptimum operating angle of the thermosyphon is50°～70°with evaporation length of270mm and filling Rate of15%.It was found that thermosyphon array studied here showed a self-repair feature inthe operating process near dry-out point according to the experimental phenomena andanalyzed the heat-transfer mechanism under the different work conditions. Byenhancing the heat flux to a certain degree, the evaporation temperature of single lateral increased rapidly, then turned down near other’s until drying out.Heat transfer capability of the concentric annular thermosyphon array is optimizedunder operating condition and design parameters in this work. This experimentalinvestigation work will play an important role for further research on the device andassembling the heat recovery system.