Research on a novel air conditioning system for improved indoor thermal environment control

The control of indoor air temperature and humidity is equally important in many different types of buildings. However, many inadequacies still exist when using traditional direct-expansion-based (DX) air conditioning (A/ C) systems to deal with variable indoor cooling loads. Therefore, a novel DX A/C system with multiple evaporators (DXME) and using R410A as the refrigerant is proposed in this study to address these problems. The operating performance of the DXME system has been experimentally studied. Experimental results demonstrate that under two working models, i.e., Model I and Model II, the proposed DXME system can output variable cooling capacities, so as to handle indoor sensible and latent cooling loads accordingly. In addition, the two models have different operating performance. Under Model I, the variation of the refrigerant flow rate influences more on the output total cooling capacity (TCC) of the DXME system, while under Model II it influences more on the equipment sensible heat ratio (E SHR). Moreover, under Model I, the variation of the air flow rate influences more on the E SHR, while under Model II it influences more on the TCC. In addition, the output TCC range under Model I is larger than that under Model II, while the E SHR ranges under two models are similar. Furthermore, both inlet air temperature and humidity affect operating performance of the DXME system, with inlet air humidity having a greater effect on it, as reflected by changes in position and shape of the operating area in the TCC-E SHR diagram.