احمدعلی ربیع نتاج درزی

In this paper, the efficiency regarding using helical-coiled tubes having corrugated wall is numerically investigated. The fluids of interest flow in laminar regime and they are in the Reynolds number of 2000–8000 and Dean number ranging from 496 to 2806. After validating a plain coil-tube with available data in the literature, effects concerning the Reynolds number, tube diameter, corrugated height and pitch on the heat transfer and pressure drop are studied. Results shows that Nusselt number increases with Reynolds number while relative Nusselt number decreases with it. Higher corrugated height and lower corrugated pitch enhances the heat transfer with further friction factor. The thermal efficiency of these cases of interest are all greater than unity and it increases by twice with decreasing tube diameter by half. It rises by increasing corrugated height, decreasing tube diameter and lowering corrugated pitch. Moreover, a Nusselt number correlation is developed which is based on numerical results, being a function of Dean number, corrugated height and pitch where it is stronger function of corrugated height compared to corrugated pitch.