Modeling of contact thermal resistance in lateral capillary tube-suction line heat exchangers with experimental validation and investigation

This paper studied the lateral capillary tube-suction line heat exchanger (CTSLHX) with different contact types and different geometries. An improved one-dimensional model of the CTSLHX was established, using the CFD model to derive the contact thermal resistance between the capillary tube and the suction tube. An experimental bench was built to test the steady-state heat transfer and flow performance. It was found that the model predicted 87.6 % and 98.9 % of the measured mass flow rate within the error band of +/- 10 % and +/- 15 %. The prediction error of the CTSLHX heat transfer effectiveness was within +/- 10 %. Parametric effects of different operating conditions and structural parameters on the performance of CTSLHX were investigated. Furthermore, experiments were carried out to study the temperature distribution along the transition section between the exit of the capillary tube and the evaporator. The unique temperature increase reveals that it is beneficial for reducing noise by wrapping a layer of rubber around the second increaser fitting.