Author : Saurabh.P.Joshi and Mahesh.R.Chopade

This paper presents an experimental attempt of enhancement of condensation heat transfer coefficient of steam in the double pipe heat exchanger using modified twisted tape insert as an enhancement technique compared to conventional simple twisted tape insert. The experiments were conducted for dry saturated steam having approximate dryness fraction X=1 at low pressures separately in two test sections of heat exchanger having horizontal pipe employing simple twisted tape in first test section and modified baffled twisted tape along with nozzle type arrangement in path of flow for swirl flow generation in second test section. Readings were taken for different flow rates of steam as well as varying inlet steam temperatures and observations have been made for effective heat transfer exchange in the form of changing inlet and outlet temperatures of condensate and coolant. Experimental as well as analytical comparison has been done in between results of simple twisted tape and modified twisted tape. Results show that for same twist ratio Y=5, baffled tape creates more swirl generations in steam path as compared to simple tape resulting in providing more contact area for heat exchange process thus ultimately causing slight enhancement in condensation heat transfer rate of steam at the expense of reasonable pressure drop. In addition, graphs have also been plotted in between heat transfer rate and flow rate of steam as well as inlet steam temperature showing relations between these entities.

Keywords: Condensation heat transfer, baffled tape, twist ratio, pressure drop.