An experimental heat-transfer study for a heat-recovery unit made of corrugated tubes

Effect of flow direction for flow and heat transfer characteristics in outward convex asymmetrical corrugated tubes

“…Plentiful studies have been carried out on the heat transfer enhancement performance of corrugated tubes including inward type, outward type and spiral type, with consideration a variety of influences and application, such as effect of corrugation ratios in ventilation device [5], effect of wall roughness compare with two other roughness shapes [6], effects of pitch-to-diameter ratio and rib-height to diameter ratio in single phase turbulent flow by using spiral corrugated tube [7], effects of Prandtl number in spiral corrugated tube [8], effect of entrance region in food industry [9], non-Newtonian fluid flow comparison between smooth and helically corrugated tubes in fluid industry [10], performance of ice slurry flow in concentric corrugated tube [11], performance of various corrugation structures in condensation flow [12][13][14] and in evaporation flow [15,16] of corrugated tube, performance of helical rib on inner side of corrugated tube [17], performance of high viscosity in corrugated tube and smooth tube [18,19], and so forth. For all the investigated situations, the consensus is that corrugated (both helical and transverse) structures fabricated on the tube wall have a significant heat transfer enhancement efficacy as compared with its smooth counterpart.…”

Large eddy simulation of turbulent flow and heat transfer in outward transverse and helically corrugated tubes

“…Corrugated tubes attracted lots of attentions due to the significant enhancement of heat transfer and limited pressure drop increases. Recently, such tubes have been investigated by many scholars using experiment and numerical methods, and many factors have been considered, such as the corrugation shape, geometrical parameters, turbulence intensity, flow velocity (Re), and working fluids (Pr) [8][9][10][11][12].…”

“…They found that, the maximum heat transfer coefficient ratio and frictional pressure drop ratio of the corrugated tubes are up to 50% and 70% higher than those of the smooth tube, respectively. The thermal characteristics of a sinusoidal corrugated tube heat exchanger were tested by Poredo s et al [9]. By using corrugated tubes the heat transfer is increased by 65-90%, and pressure drop was 3-3.5 times higher than for a smooth tube.…”

Heat transfer analysis of plain and dimpled tubes with different spacings

“…Corrugations on the walls of helically coiled tubes provide up to 25% heat transfer enhancement with a slight increase in friction factor by 2.5% . Several other studies focused on corrugated and grooved tubes to analyze heat transfer and fluid flow behavior were reported in the literature …”

“…10 Several other studies focused on corrugated and grooved tubes to analyze heat transfer and fluid flow behavior were reported in the literature. [11][12][13][14][15][16] Fan and colleagues, developed a numerical model to check the thermal performance of dimpled fin surfaces. Without additional pressure drop, a 30% improvement in heat transfer was obtained compared with flat plate fins.…”