Date of Award
Master of Science
AN ABSTRACT OF THE THESIS OF Daniel Grohmann, for the Master of Science degree in Mechanical Engineering on May 5, 2014, at Southern Illinois University Carbondale DESIGN AND CHARACTERIZATION OF A COMPACT HEAT EXCHANGER FOR USE WITH NANOFLUIDS Major Professor: Dr. Kanchan Mondal This research is aimed to design and characterize an experimental plain channel, plate heat exchanger and further compare the performance of water based nanofluids as with that of water. The thesis discusses the designing and fabrication of the heat exchanger such that several parameters such as temperature, flow rate, nanoparticle concentration, and length of channels can be varied. Three sizes of heat exchangers were fabricated. Experiments were conducted to remove heat from air at different temperatures by the various heat exchanger fluids, namely water, 0.5, 0.75 and 1 vol.% alumina in water. Flow rates of the cold fluid were varied in order to change the Reynolds Number while maintaining a laminar regime. In the experiments with water as the heat exchanger fluid, it was found that the heat exchange did not follow pure counter current flow conditions presumably due to end effects. A correction factor, F, for the log mean temperature difference value was calculated for each case to estimate the mean temperature difference. The effectiveness values were found to be greater than 0.75 for most cases. It was also found that the thermal entrance length was larger than the length of the channels for the shortest heat exchanger. In addition, it was observed that the laminar regime Nusselt number values were similar to values reported in literature for flow through mini and micro channels. Convective heat transfer coefficients were calculated and were found to be of the order of those reported for water. It was also discovered that Prandtl number was the most influential property for this study. As opposed to expectations, the use of nanofluids was found that it did not significantly improve heat transfer than that of the water alone. The only case that the nanofluids had a significant enhancement in the performance was that of the 6in plate at 1 vol.% of 11% increase. The rest of the study showed that it had no increase or negative effects.
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