Heat transfer augmentation in double pipe water to air counter flow heat exchanger with helical surface disc turbulators

Effect of Helical Surface Disc Turbulators on Heat Transfer and Friction Factor Characteristics in the Annuli of a Double‐Pipe Heat Exchanger

“…b and c present the DPHE with HSDTs and a photographic view of HSDTs used in the test specimen, respectively. The test facility includes the test specimen, water flow system, air flow system, and instrumentation scheme, as discussed by Yadav and Sahu in detail. The test specimen is a DPHE formed by a smooth inner tube and outer tube.…”

“…Double‐pipe heat exchangers (DPHEs) are widely used for both cooling and heating in various engineering and scientific applications such as heat recovery system for engine cooling, solar air heater, air conditioning, food processing industry, and chemical industry , . In general, two different techniques, namely, active and passive techniques, are employed to enhance heat transfer in various thermal devices , . The passive techniques using turbulence promoters such as artificial roughness, ribs baffles, fins obstacles, turbulators, and swirl flow devices such as conical rings, coiled‐wire twisted tape, vortex rings, and winglets , have been reported in the previous study.…”

“…The studies are made using air as working fluid through the tubes and the DPHE. Studies have been reported for various pitch ratios (0.5–12) and diameter ratios in the range of 0.31–0.69 , . The thermal performance of turbulators at various pitch ratios and diameter ratios are limited in the literature.…”

Numerical Investigation of the Effects of the Baffles Added in a Concentric Pipe Heat Exchanger

“…The numerical model for the simple concentric heat exchanger (without baffles) is validated using this method given for this type of heat exchangers. In this method, a definition for the maximum heat transfer possible is made [8] as: ̇m ax=Cmin(Th,in-Tc,in) (5) where Cmin is the minimum of ̇hc h and ̇cc c. Additionally, another definition, number of thermal units, NTU=UAs/Cmin is made in order to calculate the effectiveness of a concentric pipe heat exchanger [8] such that ̇ = ̇m ax: where c=Cmin/Cmax. As is simply the outer surface area of the inner tube.…”

“…They also indicate that the Nusselt number and friction factor vary considerably depending on the factors such as the hole spacing, void ratio etc. Yadav and Sahu [5] investigated the heat transfer augmentation in double pipe air to water heat exchanger with helical disk turbulators. They reported that the Nusselt number was found to increase with the increase in Reynolds number and helix angle and was found to decrease with increase in diameter ratio.…”