An experimental investigation of the effect of moisture on the performance of an air-conditioning system

Tests were conducted at the University of Florida´s Solar Energy and Energy Conversion Laboratory (SEECL) to determine the effect of the moisture on the performance of a 3 ton residential heat pump system with R-22 as the working fluid. The performance of the heat pump system was tested in accordance with the ARI Standard 210/240 (ARI 1989) and ANSI/ASHRAE-37-1988 for testing unitary equipment. ASHRAE´s “Air Enthalpy Method” was used to determine the performance of heat pump system and ASHRAE´s condition “A” [Outside 95°F DBT/75°F WBT; Inside 80°F DBT/67°F WBT] was maintained for the tests. The experimental data reveals that moisture levels of approximately 700 ppm in the refrigerant can decrease the system performance by 10-15%. Approximately 50-60% of the moisture injected into the system remains in the refrigerant and the rest mixes with the compressor oil. Hence, it is possible that over a period of time the moisture in the compressor oil may breakdown at the prevailing temperatures and pressures to form acids which may result in catastrophic failure