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Characterization of greywater heat exchangers and the potential of implementation for energy savings
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Service and Energy Systems.
2016 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Värmeväxlare för spillvatten – karakterisering och energibesparingsmöjligheter (Swedish)
Abstract [en]

Buildings account for up to 32% of the total energy use in different countries. Directives from the European Union have pointed out the importance of increasing energy efficiency in buildings. New regulation in countries like Sweden establishes that new buildings should fulfill regulations of Nearly Zero Energy Buildings (NZEB), opening an opportunity for new technologies to achieve these goals. Almost 80-90% of the energy in domestic hot water use is wasted from different applications with almost no use and with a lot of potential energy to be recovered.

The present work studied the characteristics of greywater heat exchanger as a solution to recuperate heat from greywater to increase efficiency in buildings. This study explored the fluid mechanics involved in the vertical greywater heat exchangers, analyzing the falling film effect present in drain pipes and the effects of the secondary flow generated in the external helical coil. A heat transfer model from a theoretical approach was proposed and validated. In addition, this study explored the different variables influencing the economic feasibility of the technology and an economic analysis was performed. A theoretical comparison between a greywater heat exchanger application and a reference case without it was evaluated highlighting the importance of all the variables involved in the potential of implementation of the technology. The technology shows big potential in households with high water consumptions, especially with electric boilers.

Place, publisher, year, edition, pages
2016. , 75 p.
TRITA-IES, 2016:01
Keyword [en]
Wastewater heat recovery, greywater heat exchanger, domestic hot water, energy savings, energy efficiency, residential households, NZEB, heat transfer modelling, feasibility study, potential of implementation, falling film effect, flow helical coil.
National Category
Energy Systems
URN: urn:nbn:se:kth:diva-191123OAI: diva2:954932
Subject / course
Building Services Engineering and Energy
Available from: 2016-08-25 Created: 2016-08-24 Last updated: 2016-08-25Bibliographically approved

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