New experimental Nusselt number correlation for spiral plate heat exchanger optimized using a code

A system of a spiral plate heat exchanger and its required auxiliaries was built. The pitches of heat exchanger were built differently to provide almost two geometrically different heat exchangers in a single package. Several experiments were done and working parameters of the heat exchanger were measured. A code was written to find a new optimised correlation that could approximate the Nusselt Number based on the obtained experimental data from 51 reliable experiments. As an advantage, that correlation was valid for low Reynolds Numbers. Also, in most of previous works, the correlation for Nusselt Number in one side of the heat exchanger was supposed to be known and the correlation for the other side was determined. But, in this study, the equation was found using calculations for both sides simultaneously. The overal heat transfer coefficient calculated from the proposed correlation, made an average error of 3.65% to the experimental data. A complete uncertainty analysis was done and revealed that the results from the new correlation for the Nusselt Number lies between +/- 3% around the real Nusselt Number.