Analysis of the application effect of energy-saving retrofit with additional evaporative cooling condenser for outdoor units of VRF air conditioning systems.

Evaporative cooling technology is pivotal in minimizing energy consumption in chiller-based air conditioning systems. An evaporative cooling add-on device was developed for outdoor units of variable refrigerant flow (VRF) systems by leveraging this principle. The device lowers condenser inlet air temperature via water curtain evaporative cooling to enhance system energy efficiency. To validate its energy-saving efficacy, this study retrofitted existing VRF systems in two distinct buildings. It tested parameters including condenser inlet air temperature, indoor supply air temperature, and power consumption under sunny and rainy conditions, comparing them to non-retrofitted systems. In Project 1, the retrofitted system achieved a maximum inlet air temperature reduction of 24.9 ◦C, yielding average energy-saving rates of 31.2 % (sunny) and 13.6 % (rainy). Project 2
demonstrated a34.1 % total energy-saving rate, alongside a 5.8 ◦C reduction in indoor outlet air temperature. Theoretical modeling predicts a 38 % potential COP gain for the refrigeration cycle, with measured system energy efficiency improvements reaching up to 35.2 %. These findings offer practical insights for energy-saving retrofitting of VRF systems, highlighting the technology’s significant potential in reducing building energy consumption.