Analysis of Thermal Characteristics of Ultra-large Negative Pressure Cryogenic Heat Exchangers

In the context of the rapid development of large-scale scientific facilities in China, the requirement for ultra-large cryogenic systems is gradually increasing. At the same time, the heat exchanger within such facilities will be subjected to even more severe and extreme working conditions. Therefore, it is essential to carry out simulation research regarding their performance under extreme operating conditions. Of course, such studies will help to achieve a more exhaustive comprehension of how they respond in diverse harsh environments in practical application. In this work, based on the ultra-large helium cryogenic system, a comprehensive simulation model of a negative pressure throttle cryogenic heat exchanger was developed. The thermal characteristics of several fin types were compared and analyzed in detail to assess their heat transfer efficiency under the extreme conditions of negative pressure, high flow rate and the superfluid helium temperature range. The present simulation results showed that under the present examined conditions, the staggered and corrugated fins exhibit significantly enhanced heat transfer performance and effectively improve the heat exchange efficiency, but at the same time, their resistance characteristics are obviously weakened, and the resistance characteristics of corrugated fins are better than those of the staggered fins in terms of resistance characteristics. The comprehensive evaluation index was rigorously established to assess the performance of several different fin types under specific conditions. The corrugated fin had better comprehensive performance compared with flat fin as well as staggered fin. On this basis, further optimization studies were carried out on the structural parameters of the corrugated fins, exploring the effects of different parameters on the performance and determining the best parameter combinations. This research result can provide a reliable theoretical basis and design reference for related engineering applications, and at the same time is of great significance for improving heat transfer efficiency, energy saving and emission reduction.