The application of u-shape heat pipe heat exchanger to reduce relative humidity for energy conservation in heating, ventilation, and air conditioning (HVAC) systems

Hospitals consume large amounts of energy, especially in their heating, ventilation, and air conditioning (HVAC) systems due to the special requirements for ensuring healthy, comfortable, and safe environmental conditions. The use of a Heat Pipe Heat Exchanger (HPHE) is recommended as a means of minimizing electricity consumption with no loss of comfort while also improving indoor air quality. An experimental study was conducted to investigate the performance of a U-shape HPHE in recovering exhaust air heat from an indoor room included in an HVAC system. The U-shape HPHE consists of several tubular U-shape heat pipes with water as a working fluid and arranged in a staggered configuration. Tests were carried out to determine the impact of the inlet air temperature, air velocity, and the number of heat pipes on its effectiveness. The experiment revealed that the higher the temperature of the inlet air, the more effective the U-shape HPHE. The results show that the temperature of the air entering the cooling coil decreased by 1.73 °C with an effectiveness value of 7.64 %. This result was achieved using 12 U-shape HPHEs, which had a staggered arrangement, an air velocity of 1.5 m / s, and an air temperature entering the evaporator of 45 °C. The highest amount of heat recovery, 2190.43 kJ/hour, was achieved when the air velocity was 2.5 m/s.