Investigation of exergy efficiency in shell and helically coiled tube heat exchangers

摘要

This study presents exergy analysis for forced convection heat transfer in shell and helically coiled tube heat exchangers. The effect of operational and geometrical parameters on the exergy efficiency was investigated. Water is selected as the working fluid of both sides. Results show that, the efficiency decreases linearly with the increase of the fluids dimensionless inlet temperature difference. Based on the results, a correlation was developed to predict the efficiency for wide range of mass flow rates ratio (0.1m<4), fluids dimensionless inlet temperature difference (0T<0.8), product of Reynolds numbers (3.31E+8<(Rec. Resh)<1.32E+9) and dimensionless geometrical parameters. According to this equation it was found that, the coil which has the maximum number of turns and minimum diameter is more efficient than other coils which have the same length and pitch.