Commenced in January 2007
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Paper Count: 30069
Experimental Investigation of Gas Bubble Behaviours in a Domestic Heat Pump Water Heating System

Authors: J. B. Qin, X. H. Jiang, Y. T. Ge

Abstract:

The growing awareness of global warming potential has internationally aroused interest and demand in reducing greenhouse gas emissions produced by human activity. Much national energy in the UK had been consumed in the residential sector mainly for space heating and domestic hot water production. Currently, gas boilers are mostly applied in the domestic water heating which contribute significantly to excessive CO2 emissions and consumption of primary energy resources. The issues can be solved by popularizing heat pump systems that are attributable to higher performance efficiency than those of traditional gas boilers. Even so, the heat pump system performance can be further enhanced if the dissolved gases in its hot water circuit can be efficiently discharged.  To achieve this target, the bubble behaviors in the heat pump water heating system need to be extensively investigated. In this paper, by varying different experimental conditions, the effects of various heat pump hot water side parameters on gas microbubble diameters were measured and analyzed. Correspondingly, the effect of each parameter has been investigated. These include varied system pressures, water flow rates, saturation ratios and heat outputs. The results measurement showed that the water flow rate is the most significant parameter to influence on gas microbubble productions. The research outcomes can significantly contribute to the understanding of gas bubble behaviors at domestic heat pump water heating systems and thus the efficient way for the discharging of the associated dissolved gases.  

Keywords: Dissolved gases in water, heat pump, domestic water heating system, microbubble formation.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1131371

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References:


[1] Centre for climate and energy solutions, “Outcomes of the U.N. climate change conference in Paris”, available at: https://www.c2es.org, (Accessed Date: 12th November 2016).
[2] R. B. Dean, The formation of bubbles, Journal of Applied Physics 15 (1943) 446-450.
[3] R. H. S. Winterton, Sizes of bubbles produced by dissolved gas coming out of solution on the walls of pipes in flowing systems, Chemical Engineering Science 27,1972, 1223e1230
[4] S. F. Jones, G. M. Evans, K. P. Galvin, The cycle of bubble production from a gas cavity in a supersaturated solution, Advances in Colloid and Interface Science 80 (1999a) 27-50.
[5] M. Blander, J.L. Katz, Bubble nucleation in liquids, AIChE Journal 21 (5) (1975) 51-84.
[6] A. M. Fsadni, Y. T. Ge, A. G. Lamers, Bubble nucleation on the surface of the primary heat exchanger in a domestic central heating system, Applied Thermal Engineering 45-46, 2012, pp. 24-32.
[7] L. Yin, L. Jia, M. Xu. Experimental investigation on bubble sliding during subcooled flow boiling in microchannel. Experimental Thermal and Fluid Science. 2015 Nov 30; 68:435-41
[8] N. H. Hoang, I. C. Chu, D. J. Euh, C. H. Song. A mechanistic model for predicting the maximum diameter of vapor bubbles in a subcooled boiling flow. International Journal of Heat and Mass Transfer. 2016 Mar 31;94:174-9.
[9] K. Nilpueng, S. Wongwises. Two-phase gas–liquid flow characteristics inside a plate heat exchanger. Experimental Thermal and Fluid Science. 2010 Nov 30;34(8):1217-29.
[10] P. Vlasogiannis, G. Karagiannis, P. Argyropoulos, V. Bontozoglou. Air–water two-phase flow and heat transfer in a plate heat exchanger. International Journal of Multiphase Flow. 2002 May 31;28(5):757-72.
[11] Y. C. Tsai, F. B. Liu, P. T. Shen. Investigations of the pressure drop and flow distribution in a chevron-type plate heat exchanger. International communications in heat and mass transfer. 2009 Jul 31;36(6):574-8.
[12] A. H. Abdelmessih, F. C. Hooper, S. Nangia. Flow effects on bubble growth and collapse in surface boiling. International Journal of Heat and Mass Transfer. 1972 Jan 1;15(1):115IN3119-8IN4125.
[13] V. Grabenstein, A. E. Polzin, S. Kabelac. Experimental investigation of the flow pattern, pressure drop and void fraction of two-phase flow in the corrugated gap of a plate heat exchanger. International Journal of Multiphase Flow. 2017 May 31;91:155-69.
[14] J. Bonjour, M. Clausse, M. Lallemand. Experimental study of the coalescence phenomenon during nucleate pool boiling. Experimental Thermal and Fluid Science. 2000 Feb 29;20(3):180-7.
[15] Y. Y. Hsieh, L. J. Chiang, T. F. Lin. Subcooled flow boiling heat transfer of R-134a and the associated bubble characteristics in a vertical plate heat exchanger. International Journal of Heat and Mass Transfer. 2002 Apr 30;45(9):1791-806.
[16] A. M. Zhang, P. Cui, J. Cui, Q. X. Wang. Experimental study on bubble dynamics subject to buoyancy. Journal of Fluid Mechanics. 2015 Aug 10;776:137-60.
[17] O. Pamperin, H. J. Rath. Influence of buoyancy on bubble formation at submerged orifices. Chemical Engineering Science. 1995 Oct 1;50(19):3009-24.
[18] J. Lu, A. Fernández, G. Tryggvason. The effect of bubbles on the wall drag in a turbulent channel flow. Physics of Fluids. 2005 Sep;17(9):095102.
[19] J. Rensen, S. Luther, D. Lohse. The effect of bubbles on developed turbulence. Journal of Fluid Mechanics. 2005 Sep 10;538:153-87.
[20] W. C. Leith, A. L. Thompson. Some corrosion effects in accelerated cavitation damage. Journal of Basic Engineering. 1960 Dec 1;82(4):795-802.
[21] Y. T. Ge, A. M. Fsadni, H. S. Wang. Bubble dissolution in horizontal turbulent bubbly flow in domestic central heating system. Applied energy. 2013 Aug 31;108:477-85.
[22] A. M. Fsadni, Y. T. Ge, A. G. Lamers. Bubble nucleation on the surface of the primary heat exchanger in a domestic central heating system. Applied Thermal Engineering. 2012 Dec 31;45:24-32.
[23] S. Lubetkin, M. Blackwell. The nucleation of bubbles in supersaturated solutions. Journal of colloid and interface science. 1988 Dec 1;126(2):610-5.