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Experimental Thermal and Fluid Science 35 (2011) 960–970 Contents lists available at ScienceDirect Experimental Thermal and Fluid Science journal homepage: www.elsevier.com/locate/etfs Effect of surfactant additives on nucleate pool boiling heat transfer of refrigerant-based nanofluid Hao Peng a,b, Guoliang Ding a,⇑, Haitao Hu a a Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China b Key Laboratory of Microgravity (National Microgravity Laboratory)/CAS Institute of Mechanics, Chinese Academy of Sciences (CAS), 15 Beisihuan Xilu, Beijing 100190, China article info Article history: Received 17 May 2010 Received in revised form 3 December 2010 Accepted 29 January 2011 Available online 3 February 2011 Keywords: Correlation Nanofluid Nucleate boiling Refrigerant Surfactant 1. Introduction Refrigerant-based nanofluid is one kind of nanofluids, in which the host fluid is conventional pure refrigerant. Experimental stud- ies showed that the refrigerant-based nanofluid has higher thermal conductivity than the host refrigerant [1], and the refrigeration system using refrigerant-based nanofluid has better performance than that using conventional pure refrigerant [2–4]. However, the aggregation and sedimentation of nanoparticles in the refriger- ant-based nanofluid may reduce the stability of refrigerant-based nanofluid and limit the application of refrigerant-based nanofluid in the refrigeration system. In order to stabilize the nanoparticles in the refrigerant-based nanofluid, one effective way is adding the surfactant into the refrigerant-based nanofluid. The presence of surfactant additives may have effects on the boiling heat transfer characteristics and then the overall performance of evaporators in the refrigeration systems because the surfactant additives change the thermophysical properties of working fluids including surface ⇑ Corresponding author. Tel.: +86 21 34206378; fax: +86 21 34206814. E-mail address: glding@sjtu.edu.cn (G. Ding). 0894-1777/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.expthermflusci.2011.01.016 abstract Effect of surfactant additives on nucleate pool boiling heat transfer of refrigerant-based nanofluid was investigated experimentally. Three types of surfactants including Sodium Dodecyl Sulfate (SDS), Cetyl- trimethyl Ammonium Bromide (CTAB) and Sorbitan Monooleate (Span-80) were used in the experiments. The refrigerant-based nanofluid was formed from Cu nanoparticles and refrigerant R113. The test surface is horizontal with the average roughness of 1.6 lm. Test conditions include a saturation pressure of 101.3 kPa, heat fluxes from 10 to 80 kW m2, surfactant concentrations from 0 to 5000 ppm (parts per million by weight), and nanoparticle concentrations from 0 to 1.0 wt.%. The experimental results indicate that the presence of surfactant enhances the nucleate pool boiling heat transfer of refrigerant-based nanofluid on most conditions, but deteriorates the nucleate pool boiling heat transfer at high surfactant concentrations. The ratio of nucleate pool boiling heat transfer coefficient of refrigerant-based nanofluid with surfactant to that without surfactant (defined as surfactant enhancement ratio, SER) are in the ranges of 1.12–1.67, 0.94–1.39, and 0.85–1.29 for SDS, CTAB and Span-80, respectively, and the values of SER are in the order of SDS > CTAB > Span-80, which is opposite to the order of surfactant density val- ues. The SER increases with the increase of surfactant concentration and then decreases, presenting the maximum values at 2000, 500 and 1000 ppm for SDS, CTAB and Span-80, respectively. At a fixed surfac- tant concentration, the SER increases with the decrease of nanoparticle concentration. A nucleate pool boiling heat transfer correlation for refrigerant-based nanofluid with surfactant is proposed, and it agrees with 92% of the experimental data within a deviation of ±25%. Ó 2011 Elsevier Inc. All rights reserved. tension, viscosity, etc. The nucleate pool boiling heat transfer is the basic type of boiling heat transfer of refrigerant-based nano- fluid in the evaporator. Therefore, the effect of surfactant additives on the nucleate pool boiling heat transfer characteristics of refrig- erant-based nanofluid must be known for evaluating the overall performance of the evaporator. Until now, the researches related to the effect of surfactant on the nucleate pool boiling heat transfer are focused on pure water [5–11], organic fluids [12,13], water–organic fluid mixtures [14,15] or water-based nanofluid [16,17], and there is no published research on refrigerant-based nanofluid. For the effect of surfactant on the nucleate pool boiling heat transfer of pure water, organic fluids or water-organic fluid mixtures, most of the researches indi- cated that the presence of surfactant enhances the nucleate pool boiling heat transfer [6–11,13–15], but some researches indicated that the surfactant deteriorates the nucleate pool boiling heat transfer or has little effect on the nucleate pool boiling heat trans- fer [5,12]. For the effect of surfactant on the nucleate pool boiling heat transfer of water-based nanofluid, the research reported by Chopkar et al. [16] showed that the presence of surfactant deteri- orates the nucleate pool boiling heat transfer, but the researchPDF Image | Experimental Thermal and Fluid Science 35
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