The objective of the present work is to study the influence of Copper nanoparticle concentration on heat transfer performance of mixed base fluid. In the present study, the performance of copper nanoparticles in (Ethylene Glycol (EG) + Propylene Glycol (PG) + Water (W)) base fluid was analyzed in the chevron-type Plate Heat Exchanger. The sol-gel method was used to prepare Copper nanoparticles (100 nm); dispersed in two different mixed base fluids of volume fractions 5%EG + 5%PG + 90%W and 15%EG +5%PG +80%W. Experiments were performed by varying the nanoparticle concentration from 0.2 to 1.0 vol %. Three different hot fluid inlet temperatures were used (55?C, 65?C and 75?C). It is revealed from the study that the rate of heat transfer increased significantly with the mixed base fluid. Result shows that at 75?C, 9%, and 14.9% enhancement in Nusselt number is obtained for 5%EG + 5%PG + 90%W and 15%EG +5%PG +80%W base fluid respectively for the nanoparticle concentration of 1%.
The objective of the study is to determine the thermo physical property variations (such as viscosity, density, specific heat capacity and thermal conductivity) of graphene suspended base fluid (Ethylene Glycol (EG) /Water (W)), with respect to graphene nanoparticle concentration and hot fluid inlet temperature. Graphene nanoparticle concentrations (0.2, 0.4, 0.6, 0.8 and 1 volume %) and the base fluid of 30:70 volume % of EG: Water is prepared initially. The impact of graphene nano particle addition on base fluids based on experimentation in the commercial plate heat exchanger was studied. In this experiment, the hot fluid inlet temperature was varied at 55? C, 65? C and 75? C. The experimental results of thermo physical properties were compared with the selected models proposed in the literature. Einstein (1956); Kitano (1981); and Bachelor models (1977) have been used to consider the effect of viscosity. The measured density and Specific heat capacity was validated with Pak and Cho and Xuan model respectively. To consider the effect of thermal conductivity, three different models (Maxwell, 1954; Vajjah, 2010; and Sahoo, 2012) have been used. Study revealed that the thermo physical properties of base fluid significantly affects with the graphene nanoparticle suspension.
This paper reports an experimental study on the heat transfer characteristics of a nanofluid consisting of ZnO/water/ethylene glycol (EG) and TiO 2 /water/ /ethylene glycol. In this study, the base fluids of ethylene glycol (EG):water (W) with volume fractions of 30:70, 40:60, and 50:50 were prepared, and 0.2 to 1.0 volume fractions of ZnO and TiO 2 nanofluids were used as a cold side fluid. The prime objective of this study is to identify the effects of nanofluid concentration and three different hot fluid inlet temperatures viz., 55, 65 and 75 °C on the heat transfer enhancement of cold side fluid. The results are compared with base fluids and the percentage increase of the Nusselt number because of nanoparticle addition is noted both experimentally and theoretically. The results showed that at the hot fluid inlet temperature of 75 °C, the increase in the Nusselt number is maximum with volume concentrations of 0.6 and 0.8% for ZnO and TiO 2 nanofluids, respectively. The corresponding maximum Nusselt number enhancements are about 11.5 and 21.4%, respectively, for the base fluid volume fraction of 30:70 (EG:W). There is good agreement between the results calculated from experimental values and the correlation.
Thermal conductivity of a heat transfer fluid plays a significant role in improving the heat transfer performance of a heat exchanger. In this work, experiments were performed in a natural convection heat transfer apparatus by mixing homogenized Al2O3 nanoparticles in a base fluid of water-ethylene glycol mixtures. The effects of heat input, nanoparticle volume content in the base fluid, and ethylene-glycol volume content in the base fluid on thermal conductivity of the nanofluid were analyzed. Based on results obtained by MINITAB? design software (factorial design matrix), 16 experimental runs were performed with the lower and higher levels of input factors. The levels for heat input were 10 and 100 W; for nanoparticle volume content in the base fluid 0.1 and 1 vol.% and for the base fluid composition 30 and 50 vol.% of ethylene glycol in water. From the obtained experimental results, a Pareto chart, normal probability plot, contour plot and surface plot were drawn. Based on the results, a new correlation was proposed, and predictions were compared with the experimental results. From the study, the maximum thermal conductivity value 0.49 W m-1 K-1 was observed at a nanoparticle volume content in the base fluid of 1.0 vol.%, ethylene glycol volume content in the base fluid of 30 vol.% and heat input of 100 W.
In this study, 23 factorial design of experiment was employed to evaluate the effect of parameters of hot fluid inlet temperature, graphene nanofluid concentration and hot fluid flow rate on thermal conductivity of graphene/water nanofluid. The levels of hot fluid inlet temperature are kept at 35°C and 85°C, nanofluid concentration is kept at 0.1 and 1.0 volume% (vol.%) and the hot fluid flow rate are kept at 2 lpm and 10 lpm. Experiments were conducted with 16 runs as per MINITAB design software using graphene/water nanofluids in the corrugated plate type heat exchanger. The nanofluid thermal conductivity was determined using the mixing rule for different nanofluid concentrations ranging from 0.1 to 1.0%. Normal, Pareto, Residual, Main and Interaction effects, Contour Plots were drawn. The Analysis of Variance (ANOVA) of test results depict that the hot fluid temperature and nanofluid concentration have significant effect on the thermal conductivity of graphene/water nanofluid (response variable).
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