Experimental study on performance of a de-foulant hydrocyclone with different reflux devices for sewage source heat pump

A de-foulant hydrocyclone (DFH) with different reflex devices was proposed to enhance the decontamination performance of DFH used in sewage source heat pump. In this study, the effects of the reflux angle and blowdown-pipe shape of the reflux device on the decontamination performance were experimentally investigated for domestic sewage and water with general-purpose polystyrene particles (GPPS). Results indicated that, the growth of the reflux angle increased the separation efficiency (for foulant, from 64% to 75%; for GPPS, from 72% to 88%) whereas reduced the energy consumption (for foulant, from 28 kPa to 23 kPa; for GPPS, from 22 kPa to 10 kPa). However, their changes were suppressed by the back pressure at the underflow orifice, which was proportional to the reflux angle. As a result, the optimum reflux angle of the DFH with a diverging blowdown-pipe is 90 degrees in the sewage source heat pump. In addition, whether the blowdown-pipe was diverging or isodiametric, the increase in the reflux angle could reduce the effect of the inlet-flow-rate fluctuation on the separation performance. We hope that this study will provide a basis for the design and manufacture of the reflux device, which is a critical component of the de-foulant hydrocyclones.