Sewage water is a heat source which provides a stable temperature of 10 – 20°C throughout the year. By exploiting this favourable condition, the Hungarian company Thermowatt developed a heat pump system which can make use of this alternative heat source.
Therefore, since July 2014, such a system provides heating and cooling for a 40 000 m2 building complex that is part of the large NATO Military Hospital in Budapest. The system provides 3,8 MW of heating and 3,3 MW of cooling using two approximately equal-sized Carrier water-water heat pumps, out of which one is an inverter, thus providing better system work and higher efficiency. The entire system, including the filtration unit, is housed in a concrete underground structure located below a car park and occupies about 210 m2. Both heating and cooling are delivered through air handling units comprising large heat exchangers and operating at just 32°C, thus contributing to the high system COP of 6,5 – 7,1. The system is fed from a collector by using gravity, and its size was determined by the amount of wastewater available – 11 000 m3/day.
The presentations from our webinar on "Large Heat Pump Applications in Europe: 15 success stories" are now available here.