Innovative algorithmic approach of determining the overall heat transfer coefficient of concentric tube heat exchangers

Heat exchanger analysis is regarded to be challenging due to the numerous parameters influencing the overall heat transfer coefficient. Errors in estimating convective heat transfer coefficients often arise from the geometric complexity of heat exchangers and varying flow regimes. The current work proposes a novel iterative method for calculating the overall heat transfer coefficients of concentric tube heat exchangers based on the Reynolds number of the two fluid streams. The approach is validated using numerical simulations performed with ANSYS-FLUENT, focusing on Reynolds numbers ranging from 4000 to 8000 for both hot and cold streams. The proposed method yields a maximum percentage of error between the CFD results and the correlation of just 1.2% for all Reynolds number combinations studied. The mean squared error (MSE) decreases by approximately 9% when 25 data points are used for the correlation fitting process compared to using only 5 data points. A comparison with existing literature correlations reveals a strong agreement within difference, demonstrating the accuracy and reliability of the developed correlation in predicting the overall heat transfer coefficients in concentric tube heat exchangers over the investigated range of Reynolds numbers.