Investigation of Household Refrigerator With Alternative Low Global Warming Potential Refrigerants
by Daniel Thomas Leighton
Steady-state and transient thermodynamic models of the refrigeration system were created in order to predict the performance of household refrigerators using different refrigerant types. The models were validated with experimental data taken from a commercially available household refrigerator charged with HFC-134a. The models were then used to simulate the drop-in performance of several alternative low global warming potential (GWP) refrigerants in the household refrigerator. The alternative refrigerant of strongest interest was HFO-1234yf, which was evaluated as a direct drop-in replacement for HFC-134a. HFO-1234yf was found to be a suitable replacement for HFC-134a, with similar performance characteristics and a decrease in overall system efficiency of less than 2%. A parametric study of HFC-134a/HFO-1234yf blends was also conducted in order to evaluate their potential as non-flammable, low GWP replacements for HFC-134a.
http://hdl.handle.net/1903/11574
Experimental Study of Hybrid Cooled Heat Exchanger
by Han-Chuan Tsao
A test system for a hybrid cooled heat exchanger was designed, and the test facility was constructed based on ASHRAE Standard 41.2-1987. A conventional air-cooled tube-fin heat exchanger was tested with and without application of wetting water. The baseline tests were conducted to investigate the heat exchanger performance improvement by applying evaporative cooling technology. The heat exchanger capacity and air side pressure drop were measured while varying operating conditions and heat exchanger inclination angles. The results show the heat exchanger capacity increased by 170% with application of the hybrid cooling technology, but the air side pressure drop increased by 130%. Additional research investigating air fan power was also conducted, which increased 120% from the dry condition to the hybrid cooled condition. In summary, the potential for improving the heat exchanger performance by applying hybrid cooling is shown in this research.
http://hdl.handle.net/1903/12366
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