Analysis of longitudinal fin patterns in a concentric double tube heat exchanger using LMTD and CFD techniques

In this paper an analysis has been done to study the effect of different longitudinal fin patterns on overall heat transfer coefficient and rate of heat transfer in concentric double tube heat exchanger using LMTD. More over the temperature distribution inside the tube heat exchanger is found and tabulated using computational fluid dynamics (CFD) by fluent 6 and meshed using GAMBIT. The inner and outer tube diameters were fixed to be 0.03m and 0.06m respectively. The following assumptions were considered for (software) analysis: (i) Fluid flow is laminar. (ii)Hot water passes through the inner tube and cold water in the annular gap for all the 4 cases (Mention no. of cases considered). (iii) Aluminium is used as the tube and fin material, the tube thickness of both the tubes is 0.001m. The inlet of hot water is constant at 370°K and that of the cold water at 300°K. Analysis showed that maximum heat transfer (rate or over all heat transfer coefficient) was observed in the case of having external fins for the inner tube with higher overall heat transfer coefficient of 60.5% increase to that of the base setup.