Evaluating the deterioration of a concentric heat exchanger using energy and exergy degradation factors

Authors: Esam I Jassim

Volume 9, Issue 4, Paper No. 090404


  The aim of the present study is to develop a new technique for assessing the sustainability of concentric heat exchanger through quantifying the deterioration caused by energy destruction and entropy generation.  The study also addresses the interconnection between heat capacity rate, flow rate, exchange flow configuration, and the sources of energy destruction. The degradation of the exchanger performance is portrayed by the newly-developed coefficients. The outcome of the study shows that heat capacity rates of cold and hot fluids have remarkable impact on the effectiveness of the heat exchanger, particularly when the ratio of such capacity rate is close to unity. Quantitively speaking, by doubling the cold fluid flow rate, the effectiveness declines by ~13% since the minimum capacity ratio is also doubled. However, as the flowrate of the cold fluid further increases, the effectiveness ameliorates by ~ 6.5 % for parallel flow and 37.5% 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%.

Keywords: Energy Degradation Factor; Exergy Degradation Factor; Concentric Heat Exchanger; Exergy Efficiency; Irreversibility; Heat Capacity Rate.

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