Enhancement in heat transfer characteristics by using truncated conical turbulators in a double pipe heat exchanger under turbulent conditions

Abstract

AbstractThe rising use of fossil fuels has had major environmental impacts, including global warming, pollution, and higher heating system costs. This emphasizes the need of increasing the efficiency of equipments such as heat exchangers used in heating and air conditioning systems. In the present study, heat transfer augmentation in a double pipe heat exchanger is numerically studied by the use of truncated conical turbulators. Truncated conical structures with a base diameter of 12 mm height, 7 mm, and pitch values ranging from 25 mm to 100 mm with an increment of 25 mm, have been considered in the study. The air flow rate varied from a Reynolds number of 3000 to 15,000 in increments of 3000. Results have been compared with the bare pipe without any turbulators. The heat exchanger with the turbulator showed better performance than the bare heat exchanger in terms of higher Nu, but at the cost of higher pressure drop. Increased Nu was observed up to pitch 50 mm and reduced afterward. Results indicated a highest Nu of 77.7 for Pitch 50 mm at Re 15,000. Maximum Thermohydraulic efficiency of 1.13 was observed for pitch 50 mm at a Re of 11,000. Hence, it is concluded that truncated conical structures can be used as a heat augmentation device in a double pipe heat exchanger to increase the heat transfer rate and thermohydraulic efficiency.

Keywords

• conical turbulator
• turbulent intensity
• contour plot
• thermohydraulic performance parameter
• turbulent