Experimental study of the separation performance of a novel sewage hydrocyclone used in sewage source heat pump

Sewage source heat pump has the remarkable benefit of energy-saving and is favorable for environment protect. However, one of the main challenges in its application is the blockage issue of heat exchanger triggered by the foulant. The untreated urban sewage contains high-concentration foulant (<4 mm) which is overwhelmingly arduous to be filtered out by the traditional mechanical filtration device. A novel sewage hydrocyclone with reflux function is proposed in this paper with the target of removing the foulant from sewage continuously and in result solving this blockage problem. In order to investigate the performance of this novel device, an experimental set-up was built and a series of research was conducted based on three kinds of sewage: the sand water, high-concentration sewage, and low-concentration sewage. The effects of feed flow rate, feed foulant concentration and feed foulant density on the separation performance were investigated respectively. The experimental results manifested the novel sewage hydrocyclone had an effective separation efficiency of 99.53-99.94% for the sand water, 91-95% for the high-concentration sewage, and 56-72% for low-concentration sewage. The split ratio stayed below 10%. Meanwhile; the pressure drop through the unit kept below 30 kPa. The test data in this study demonstrated clearly that the novel sewage hydrocyclone had a high efficiency to separate foulant (<4 mm) from the sewage continuously so as to prevent the blockage of sewage heat exchanger in the application of heat pump system. Results also can be taken as references for the heat pump designers. (C) 2016 Elsevier Ltd. All rights reserved.