Study on the overall heat transfer coefficient for the tube-in-tube heat exchanger used in mixed-gases coolers

In this paper, an experimental set up is established to investigate the behavior of the heat exchanger with multi-components mixtures based on a real mixture refrigeration system. Two tube-in-tube heat exchangers with different configurations are tested extensively with different mixtures operating at three typical temperature ranges,, such as 80K-100K, 120K-150K, and 180K-200K temperature ranges. The two heat exchangers are fabricated specially to be able to measure the temperatures and pressures distributions. With the measurement of the mixture compositions, temperatures, and pressures, the thermodynamic and hydraulic behaviors of the two heat exchangers are studied extensively. Finally, the heat transfer characteristics are obtained, which is useful in future design of the mixture refrigeration system.