Effect of Heat Capacity Ratio and Reynolds Number on the Energy and Exergy Performance of a Concentric Heat Exchanger

An experimental analysis is conducted to highlight the variation in energy and exergy efficiencies with the annulus flow Reynolds number and the capacity ratio of the two fluid (Cc/Ch). The study also presents the influence of the flow arrangement (parallel vs. counter) flow for optimization purposes. The domain of the capacity ratio in this study is of order of unity while the domain of the annulus flow Reynolds number is in the range of 5000-12000.Results showed that the capacity ratio of the fluids has considerable effect on the effectiveness of the heat exchanger, particularly when the ratio approaches unity. When the mass flow rate of the cold fluid is doubled, the exchanger efficiency declines by ~14%. However, further increase in the flowrate of the cold-side fluid, the effectiveness augments by ~ 7 % for parallel flow and 38% for counter flow, succeeding the reduction in the minimum capacity ratio by ~25% and 34 %, respectively. Experimental observation confirmed that deterioration due to irreversibility production generates eminent penalties in the exchanger performance, decreasing the exergy efficiency up to 52%.