Experimental research on heat transfer characteristics of helical coil heat exchanger with varying pitch for laminar fluid flow

Abstract

To Study on rate of heat transfer in heat exchanger using helical coils has been studied by many researchers. There is less published literature available on varying pitch helical coil heat exchanger and detail characteristics of helical coil varying pitch by keeping constant curvature ratio considering heat exchange between fluid to fluid heat exchanger for laminar flow condition not available in the present available literature. Hence in present study three different coils with varying pitches are used to investigate the heat transfer characteristics of a Helical Coil Heat Exchanger. Hence coil of 25mm, 30mm, 35mm are used by keeping constant curvature ratio (δ=0.0667), experiment is conducted to study the influence of varying pitch on effectiveness, heat transfer rate, over all heat transfer co-efficient and Nusselt Number. The experiments is conducted in horizontal counter steady flow condition and changing the flow rate of hot fluid, pitch of helical coil heat exchanger. The results show that the varying pitch of helical coil heat exchanger has influence on heat transfer characteristics. The effectiveness of the helical coil heat exchanger is decreases with increase in mass flow rate of the hot fluid inside helical tube for varying pitch considered for study. The heat transfer rate of the helical coil heat exchanger is increases with increase in Dean Number of the hot fluid inside helical tube for varying pitch considered for study. The overall heat transfer coefficient increases with increasing hot water mass flow rate. The Nussult Number at different dean number increases for increasing helical coil pitch however the trend of average heat transfer rate for increasing M Number for varying pitch observed similar. By increasing the coil pitch of helical coil heat exchanger decreases Nussult Number, inside overall heat transfer coefficient, heat transfer rate and effectiveness.