Experimental Study of Thermal Analysis and Friction Properties of Double Pipe Heat Exchangers for Different Spaces Between Spiral Grooves

Abstract

The aims of the experiment investigate the thermal performance and the friction properties of double-pipe heat exchangers scratched by spiral grooves with various different spaces between grooves. These experiments involved the use of an aluminum pipe with outer diameter of 19.8 mm and an acrylic shell pipe with inner diameter of 27.5 mm. The depth and width of these grooves remained constant at about 0.5 mm, and 1 mm respectively. The distance between spiral groove was determined of 6, 8, 10, and 12 mm. With water as working fluid and the cold fluid Reynolds number ranging from approximately 32600 up to 44600, it was observed that grooved pipes had higher friction factors than smooth pipes. The friction factor decreases with the space between grooves increases and vice versa. Heat transfer rates in grooved pipes were 1.2–1.8 times higher than in smooth pipes. The performance of heat transfer increase with decreasing the space between grooves. The Number of Transfer Units (NTU) and effectiveness also have a good correlation with increase the Reynold number, on the other hand, a decrease of spiral groove spacing. Nusselt numbers for spiral grooved pipes were higher than for smooth pipes. These are corresponding improvements over the smooth pipe strength by 3.3% for the 6 mm groove spacing. The enhancement in Nusselt number decreased with increasing distance between grooves. This study provides insights into optimizing the spiral groove spacing in double pipe heat exchangers to enhance the performance of heat transfer with pressure drop penalty.