Thermal performance of brazed plate heat exchangers for a mixed-refrigerant Joule–Thomson cooler

• Three brazed plate heat exchangers are utilized as recuperative heat exchanger.
• The mixture's overall heat transfer coefficient is experimentally investigated.
• The exergy efficiency of the recuperative heat exchanger is analyzed.
• Two correlation combinations of two-phase are recommended for use.
• The thermal resistances of mixture's two-phase heat transfer process are analyzed.

The objective of the present work is to contribute to the development of a brazed plate heat exchanger as the recuperative heat exchanger for a mixed refrigerant Joule–Thomson cooler. In this study, the thermal performance of the recuperative heat exchanger is experimentally investigated. For the recuperative heat exchanger, the overall heat transfer coefficient varies from 38.3 to 362.5 W m−2 K−1 and the exergy efficiency is in the range of 54.2–85.7%. Moreover, four condensation correlations and ten evaporation correlations were utilized to assess the mixture's two-phase overall heat transfer coefficient, with the modification of the mixture's mass transfer resistance. The experimental data are well-predicted by two correlation combinations with mean absolute errors of 17.1% and 15.8%, respectively. Hence, these two correlation combinations are recommended for use. Finally, the thermal resistances of the mixture's two-phase transfer process are evaluated by the correlation combination, that best predicts the experimental data.