Two-phase Refrigerant Flow in the Evaporator of a Stirling Cooling System with a Thermosyphon Loop

In this study, implementation of a thermosyphon heat exchanger into a Stirling refrigeration system is demonstrated by means of both theoretical and experimental analyses. R-134a was employed as the working fluid which formed a liquid column at the condenser exit, enabling a two-phase flow through the evaporator. Experiments were conducted in a controlled chamber. Cooling capacity, coefficient of performance, and two-phase pressure drop of the cooler were compared at two different voltages. The flow regime for the refrigerant in the evaporator was found to be stratified based on the calculated wavy flow and Lockhart-Martinelli parameters.