Performance comparison of air-cooled and water-cooled air-conditioners applied in residential buildings

The objectives of this study are to evaluate the water-cooled technology for residential cooling applications. A split air-cooled and a prototype water-cooled air-conditioner was set up for experimental test at different indoor and outdoor conditions. The units' cooling output, power consumption and coefficient of performance (COP) were calculated as baselines for comparison. The experimental results showed that the water-cooled air-conditioners (WACs) output more cooling load and cost less power than air-cooled air-conditioners ( AACs). The COP of WACs increases in the range of 7.23%~28.6%. The performance characteristics of WACs were modeled based on the experimental data and the predictions agree reasonably well with the experimental results at different indoor cooling load and outdoor conditions. RMS error between simulations and measured data was within 11%. The models were further used to simulate the potential energy saving compared with AACs when were applied in high-rise residential buildings in Hong Kong. The results show 20.4% energy savings over air-cooled units while the increase in condensing water system consumption is 31.1%. The overall energy savings were estimated at 16.2%. The benefits of the water-cooled AC units have been assessed technically in order to justify its potential for wider residential building applications.