Experimental investigation for utilization of U-shaped heat pipe heat exchanger in the air-conditioning system

Energy conservation is a key focus in various industries, particularly in HVAC systems. Air conditioning, being one of the most energy-intensive systems, requires significant efforts to reduce energy consumption. U-shaped heat pipe heat exchangers (U-HPHE) offer an effective and cost-efficient solution for applications with high energy demands. The purpose of this study is to investigate whether U-shaped heat pipe heat exchangers (U-HPHE) can lower HVAC system energy usage while preserving desired temperatures. U-HPHE units, containing a working fluid at a 50 % fill ratio, were tested for their impact on HVAC performance, specifically for dehumidification and Coefficient of Performance (COP) improvements. The heat pipes were placed horizontally around the cooling coil and tested in one- and two-row configurations, each with seven pipes. Fresh air temperatures and velocities were varied between 35 and 55 °C and 2–3 m/s. Results showed that using acetone-filled U-HPHE improved temperature differences in both evaporator and condenser. Higher inlet air temperatures, especially with acetone-filled heat pipes, increased heat recovery and effectiveness. The maximum heat recovery was achieved at an intake air temperature of 55 °C and an air velocity of 2 m/s, reaching 535 W and an effectiveness of 0.56.