Sunil Chamoli

Thermal Behavior in Rectangular Channel Duct Fitted With V-Shaped Perforated Baffles

An experimental investigation has been carried out to study the heat transfer and friction factor characteristics of a V-down-perforated baffled roughened solar air heater duct. The roughened wall was uniformly heated and the rest three walls of the duct were kept insulated. Measurements have been carried out for the duct aspect ratio of 10, Reynolds number range of 3800–19,000, relative hole position range of 0.429–0.571, relative roughness pitch range of 2–4, and open area ratio range of 12–44%. The relative roughness height of 0.4 and angle of attack of 60° are kept constant during the entire experimentation. The heat transfer and friction factor data obtained were compared with the data obtained from a smooth duct under similar operating conditions. In comparison to the smooth duct the V-shaped perforated baffle roughened duct enhanced the Nusselt number and friction factor by 2.57 and 5.96 times, respectively. The thermohydraulic performance parameter is found superior for the open area ratio of 24% and relative roughness pitch of 2.5.

Experimental Investigation on Thermo-Hydraulic Performance of Heat Exchanger Tube with Solid and Perforated Circular Disk Along with Twisted Tape Insert

ABSTRACT Heat transfer enhancement in heat exchanger by using passive approach has become a very versatile area of research for the researchers. Although very significant results has been achieved in the thermal performance of heat exchangers, especially in the range of lower Reynolds number, but still these passive approaches of heat transfer enhancement is not effective for the range of higher Reynolds number. In the present work the effect of ‘perforated circular disk turbulators with and without twisted tape’, on heat transfer, friction factor and thermal performance of heat exchanger is evaluated experimentally. The different geometrical parameters used for the experiment include fixed diameter ratio (0. 8), pitch ratios (1, 2, and 3), perforation index (0%, 8%, 16%, and 24%), fixed twist ratio (2) and fixed width ratio (0.4). The experiment is done in the range of Reynolds number lying from 6,500 to 26,500. On the basis of experimental observation, there is 2.2–3.54 times improvement in heat transfer and around 1.18–1.64 times improvement in thermal performance factor over smooth tube heat exchanger.