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Heat recovery from sewer systems


Professor Jan Hofman


Thursday 17 March 2016 at 1.15pm


Room 4.10, Chancellors' Building, University of Bath (Location and maps)


Do you ever think about how much energy you are washing away when taking a shower? Or how much heat is lost from your house with the wastewater? In a modern house this can be up to 40 % of the total energy use for room heating and production of hot tap water. Recovering and re-using that heat can significantly increase the energy efficiency and reduce the carbon footprint of a house. In Switzerland, Germany and Scandinavia, systems are in operation that can recover thermal energy from wastewater. Research in The Netherlands and recently at the University of Bath campus gives insight into the availability of thermal energy in the sewer system. The heat availability follows the patterns of water consumption at home. Most of the heat is available during two large peaks every day. The largest is the morning peak. At that time many people take a shower after waking up. The second peak is during the afternoon and evening, when people come back home from work.

Modelling tools to describe the water use at home have been used to predict the water flow and temperature of water entering the sewer system at home. A hydraulic sewer network model coupled with a heat balance equation was used to predict the heat loss in sewers and calculate the availability of heat in sewer networks. Experimental data from Amsterdam and the Bath campus are used to validate the models. The presentation will explain the details of heat recovery from sewer systems, the use of modelling and opportunities to re-use the heat.