Numerical Investigation of the Effect of Edge Length of Square Helical Wires on Heat Transfer and Pressure Drop

Abstract

Heat transfer and applications are among the most important research topics of the industry. The most important factor investigated in this paper is to achieve high heat transfer with less energy. Efforts to improve heat transfer in heat exchangers are an example of this. In this study, the effect of the length of the square helical wires placed in the circular pipe on the heat transfer and pressure drop was investigated numerically. All results were obtained using the k-ℇ turbulence model in the ANSYS FLUENT module. The equations used in the verification were compared with the Dittus-Boelter equation and the Nusselt number friction factor in the turbulent regime with numerical results. It has been observed that the results of the smooth pipe obtained numerically and the results of the empirical relations are quite close to each other. The cross-sectional length of the inserted helical wires is 3, 4, and 5 mm. The pitch ratio of the placed helical wires is 1. The Reynolds number research range is between 5175 and 24,575. According to the obtained results, both the Nusselt number and the friction factor increase with increasing edge length. In addition, higher efficiency is obtained at a low Reynolds number according to the thermo-hydraulic thermal performance criterion (PEC). The highest PEC was seen in the helical wire with a cross-section length of 3 mm, with a value of 1.25. However, it is observed that the PEC of 5 is greater than 4 and 3 with increasing Reynolds number.