Refrigerant Charge Distribution in Unitary Air-conditioning Units

Abstract

To address the global warming, reduction of refrigerants charge in HVAC systems is becoming an essential topic. An experimental setup was designed and built for investigating the cyclic degradation performance and the refrigerant charge distribution of a unitary air-conditioning unit. A code tester featuring two parallel ducts was developed to properly control air flows according to the ASHRAE standard test conditions. First, baseline tests were carried out under ASHRAE standard test conditions. System performance was compared to manufacturer’s specifications to validate the accuracy of the experimental setup. Second, the transient performance of the unit was analyzed and presented, and the degradation coefficient of the unit was evaluated. Third, an approach of refrigerant charge distribution measurement was proposed and implemented. Refrigerant R410A charge distribution tests were conducted under steady-state conditions and the results were compared with published results of the refrigerant charge distribution in various types of air-conditioning units. It was concluded that the system charge distribution was significantly influenced by various component combinations and the length of refrigerant copper tubing.