Heat transfer and friction factor correlations for double pipe heat exchanger with inner and outer corrugation

The double pipe heat exchanger (DPHE) is one of the most widely applicable heat transfer devices in many industries. In this study, numerical simulation is carried out to investigate a corrugation effect on the outer and inner surface of the inner tube in the double pipe heat exchanger. The liquid water is used as working fluid. The operating Reynolds number (Re) ranged from 4000 to 20000 and the constant temperature condition was imposed on the tube wall. The two kinds of tube named as internally corrugated inner tube (ICIT) and externally corrugated inner tube (ECIT) are modeled and numerically studied at three different helix angles (alpha) 15 degrees, 20 degrees, and 25 degrees using the k-epsilon turbulence model. These numerical simulation results in heat transfer coefficient, frictional loss, drop in pressure, and rate of heat transfer. The findings indicated that externally corrugated inner tube (ECIT) shows greater efficiency with those from internal corrugated tube. The PEC was obtained higher for ECIT at alpha = 15 degrees. Additionally, this investigation also develops correlations for heat transfer (Nu) and friction factor (f) and indicated maximum divergence between calculated and numerical values for Nu and f is +/- 5% and +/- 10% respectively.