Experimental investigation on using building shower drain water as a heat source for heat pump systems

Heat pumps are high-efficiency heat transfer devices with different usages, which can work by using various energy sources. This helpful device can be mixed with multiple technologies to make more efficient systems. In this study, a combination of heat pump and shower drain water is proposed to utilize wastewater deriving from the high-rise building’s bathroom. This heat pump system uses waste heat of bathroom-drained water, which is a cheap energy source compared to fossil fuel in Turkey. The mentioned heat pump system can also use wastewater from sauna, public bath, building bath, etc. to be effectively applied not only for water heating but also for space heating. In this work, it is proposed to utilize wastewater as heat source for heat pump system. In this regard a heat recovery system has been designed and combined with a heat pump system to utilize the available energy in the drained shower water. Accordingly, a wastewater gathering tank has been designed and manufactured to reuse the waste heat of the drain water. In addition, a conventional boiler has been used in the designed system to meet intended heat demand. Then the performance of the heat pump was analyzed in different wastewater temperatures. As a result, COP approximately improved by 55% when the drain water temperature increased from 15°C to 33°C. The obtained experimental results in this study showed that shower drain water thermal energy can be used successfully as a heat source for heat pump systems.