In the process of designing, manufacturing, and optimizing heat exchangers used in vapor-compression refrigeration cycles, accurate analysis of heat transfer and fluid flow behavior plays a crucial role in improving energy efficiency and overall system performance. One of the main challenges in this area is investigating the impact of variations in the overall heat transfer coefficient on the thermal performance of the exchanger and the final efficiency of the refrigeration cycle. In this study, numerical modeling and simulation of fluid flow and heat transfer in a Suction-Line Heat Exchanger (SLHX) with two different geometric configurations—tangential and concentric—were conducted using COMSOL Multiphysics 5.5 and the drift-flux model for two-phase flow. The results show that the concentric configuration exhibits a higher heat transfer coefficient due to lower thermal resistance compared to the tangential design. In both configurations, pressure drop is linear in the single-phase region and increases sharply in the two-phase region due to accelerational losses. In the concentric configuration, due to the larger inner diameter of the capillary tube, the total pressure drop is lower, and flow choking occurs later than in the tangential arrangement. This type of heat exchanger not only prevents liquid refrigerant from returning to the compressor but also reduces the vapor quality at the evaporator inlet, enhancing its efficiency. Based on the simulation results, the average heat transfer coefficient in the concentric configuration was measured to be up to four times higher than in the tangential configuration. These findings can serve as a reference for optimal heat exchanger design in cooling and air-conditioning systems.