Energy-Saving Analysis and Heat Transfer Performance of Wastewater Source Heat Pump

Abstract:

There is a large potential in the heat loss from the urban wastewater. In all kinds of low-grade heat sources, urban wastewater is gradually widely used because of its advantages such as huge quantities, small variation of temperature, warm in winter and cool in summer, etc. By integrating a heat pump to utilize this heat, the wastewater source heat pump (WWSHP), which is a new water reuse and treatment strategy to tackle the water problems of China and to realize the sustainable development, recovers the heat of wastewater. The WWSHP air conditioning system as residential application can reduce the need of energy systems based on fossil fuel for cooling, heating, and hot water's supply purposes. The system's working principle, classification and the wastewater's characteristic parameters were discussed in this paper. And the scheme of using WWSHP system for central air-conditioning compared with other refrigerating and heating equipments was analyzed in detail. The investigation into COP (Coefficient of Performance) and PER (Primary Energy Ratio) was shown in this paper. Among the four kinds of common air conditioning units, when the loads are same respectively, the WWSHP has the most significant energy-saving effect. Furthermore, mechanism of heat transfer enhancement for falling-film evaporation and condensation surface of tubes packed with wire-mesh is also studied in detail. Theoretical simulation will be carried out for the heat transfer process and the flow of falling-film outside horizontal tubes. Improvement of controlling parameters influenced the evaporation and condensation performance, and then led to an increase in the refrigerating quantity and the COP. Consequently, this WWSHP system has its theoretical significance and promising engineering application potentials for the residential refrigerating and air-conditioning system using low-temperature waste heat source.

• Periodical: Applied Mechanics and Materials (Volume 694)
• Pages: 211-217
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.694.211
• Online since: November 2014
• Authors: Ya Xiu Gu*, Tian Wang, Wei Liu, Feng Feng Ma
• Keywords: Energy-Saving, Heat Transfer, Wastewater Reuse, Wastewater Source Heat Pump

References

[1] J. Zhang, X.S. Cao, X.Z. Meng: Sustainable urban sewerage system and its application in China. Resources, Conservation and Recycling, Vol. 51 (2007), pp.284-293(In Chinese).

DOI: 10.1016/j.resconrec.2006.10.001

[2] R.E.H. Sims: Bioenergy to mitigate for climate change and meet the needs of society, the economy and the environment. Mitigation and Adaptation Strategies for Global Change, Vol. 8 (2003), pp.349-370.

DOI: 10.1023/b:miti.0000005614.51405.ce

[3] J.B.H. Nielsen, T.A. Seadi, P.O. Popiel: The future of anaerobic digestion and biogas utilization. Bioresource Technology, Vol. 100 (2009), pp.5478-5484.

DOI: 10.1016/j.biortech.2008.12.046

[4] X.L. Zhao, L. Fu, S.G. Zhang, Y. Jiang, Z.L. Lai: Study of the performance of an urban original source heat pump system. Energy Conversion and Management, Vol. 51 (2010), pp.765-770.

DOI: 10.1016/j.enconman.2009.10.033

[5] N.C. Baek, U.C. Shin, J.H. Yoon: A study on the design and analysis of a heat pump heating system using wastewater as a heat source. Solar Energy, Vol. 78 (2005), pp.427-440.

DOI: 10.1016/j.solener.2004.07.009

[6] R.H. Wu, C.H. Zhang, D.X. Sun, G.X. Ma: Research on the soft-dirt characteristic of heat-exchanging pipe in using urban original wastewater as cooling and heating source. Fluid Machinery, Vol. 34 (2007), pp.58-61(In Chinese).

[7] J.F. Qian, R.H. Wu, D.X. Sun: Effect on fluxion and heat transfer due to the thickness of soft dirt in shell sewage heat exchanger. Fluid Machinery, Vol. 35 (2007), pp.74-78(In Chinese).

[8] R.H. Wu, Y. Xu, D.X. Sun, N.Q. Ren: Research and utilization progress of intake water heat-exchange technique of sewage and surface-water source heat pump systems. Heating Ventilating & Air Conditioning, Vol. 38 (2008), pp.25-30(In Chinese).

[9] R.H. Wu, Y. Xu, D.X. Sun, N.Q. Ren: Technology economic analysis of heat pump temperature rising in sewage disposal process in cold climate area. Act energiae solaris sinica, Vol. 29 (2008): pp.267-271(In Chinese).

[10] Y.X. Gu, H.Q. Deng: The feasibility analysis of wastewater source heat pump using the urban wastewater heat. Research Journal of Applied Sciences, Engineering and Technology, Vol. 4(18) (2012), pp.3501-3504.

[11] Y.X. Gu, Y.L. Guan, Q.L. Meng: Research on falling-film performance of a new solar LiBr absorption refrigeration system. Energy Education Science and Technology, Part A Energy Science and Research, Vol. 30(1) (2012), pp.199-206.