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The Scientific World Journal
Volume 2014, Article ID 503624, 6 pages
Research Article

Flow Characteristics of the Raw Sewage for the Design of Sewage-Source Heat Pump Systems

1School of Energy and Architecture, Harbin University of Commerce, Harbin 150028, China
2School of Municipal & Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China
3State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China

Received 10 March 2014; Accepted 18 April 2014; Published 12 May 2014

Academic Editor: Ebrahim Momoniat

Copyright © 2014 Ying Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The flow characteristics of raw sewage directly affect the technical and economic performance of sewage-source heat pump systems. The purpose of this research is to characterize the flow characteristics of sewage by experimental means. A sophisticated and flexible experimental apparatus was designed and constructed. Then the flow characteristics of the raw sewage were studied through laboratorial testing and theoretical analyses. Results indicated that raw sewage could be characterized as a power-law fluid with the rheological exponent being 0.891 and the rheological coefficient being 0.00175. In addition, the frictional loss factor formula in laminar flow for raw sewage was deduced by theoretical analysis of the power-law fluid. Furthermore, an explicit empirical formula for the frictional loss factor in turbulent flow was obtained through curve fitting of the experimental data. Finally, the equivalent viscosity of the raw sewage is defined in order to calculate the Reynolds number in turbulent flow regions; it was found that sewage had two to three times the viscosity of water at the same temperature. These results contributed to appropriate parameters of fluid properties when designing and operating sewage-source heat pump systems.