Experimental measurement of heat recovery from shower wastewater

Abstract

The wastewater generated during showering represents a potential source of low-grade thermal energy that can be utilised to reduce the energy required for domestic water heating. This paper presents an experimental investigation of a shower wastewater heat recovery system in laboratory conditions. Measurements were carried out during summer and autumn periods under operating modes with and without heat recovery for 6- and 10-minute showering cycles. Temperatures and flow rates of the hot water, cold water, preheated cold water, mixed water, and wastewater were monitored.The results showed that the temperature of the cold water flowing through the heat exchanger increased by approximately 6–6.5 K. The experimentally determined heat exchanger efficiency reached 38–39 %, while the relative heat savings were approximately 23 %. The measurements also confirmed the effect of real operating conditions, particularly ambient temperature and non-insulated pipelines, on the measured parameters.