Experimental studies of a double-pipe helical heat exchanger

An experimental study of a double-pipe helical heat exchanger was performed. Two heat exchanger sizes and both parallel flow and counterflow configurations were tested. Flow rates in the inner tube and in the annulus were varied and temperature data recorded. Overall heat transfer coefficients were calculated and heat transfer coefficients in the inner tube and the annulus were determined using Wilson plots. Nusselt numbers were calculated for the inner tube and the annulus. The inner Nusselt number was compared to the literature values. Though the boundary conditions were different, a reasonable comparison was found. The Nusselt number in the annulus was compared to the numerical data. The experimental data fit well with the numerical for the larger heat exchanger. But, there were some differences between the numerical and experimental data for the smaller coil; however these differences may have been due to the nature of the Wilson plots. Overall, for the most part the results confirmed the validation of previous numerical work. (c) 2005 Elsevier Inc. All rights reserved.