Heat transfer analysis in open pan heat exchanger (OPHE) with different cross-sections of conduits for jaggery processing

Abstract

India leads the world in jaggery production, with the jaggery industry being a vital rural-based sector. The jaggery plants in the country face challenges in effectively utilizing energy, resulting in varying efficiency levels ranging from 20% to 65% across different plants. To address this, a modified approach employing open pan heat exchangers (OPHEs) in jaggery plants is proposed to enhance overall performance. The effectiveness of the heat exchanger (HE) relies on factors such as heat transfer coefficient (HTC), surface contact area, and temperature differences between surfaces and the warm liquid. Circular conduits are predominantly favored in HE design, but this study delves into the impact of conduit shapes specifically circular, semi-circular, and square on the achievement of the HE. The study reveals that semi-circular conduits outperform circular conduits by 25%–28% in terms of HTC, while square conduits show a 21%–24% improvement. Moreover, comparing the efficiency of a conventional open pan jaggery plant with a circular conduit OPHE and a modified version featuring semi-circular conduits OPHE, significant improvements are noted. A one hp pump is enough to overcome the issue related to pumping power due to a change in conduit shape. Heat transfer rate (HTR) is very poor for circular conduit due to line contact, whereas HTR for semi-circular conduit is 38%–39% better than the square conduit. Efficiency increases from 24.36% for the conventional open pan to 62.5% for the circular conduit and further to 83.22% for the semi-circular conduit. Processing time for jaggery making also varies significantly, with 165 min for the conventional open pan, which is reduced by 33.33% for the circular conduit OPHE and 45.45% for the semi-circular conduit OPHE. As compared to circular conduit processing time of semicircular conduit OPHE is reduced by 18.18%.