Enhancing heat transfer in heat exchanger tube using four-shape cutting cone (FSCC) inserts: a numerical analysis

Abstract

The study introduces a new design modification for regular smooth tubes, incorporating the four-shape cutting cone (FSCC) to enhance heat transfer without increasing friction charge. Numerical simulations are used for processes heat and flow characteristics in the turbulent flow regime using certain parameters, ranging from 4000 ≤ Re ≤32,000. FSCC inserts can improve heat transmission, which lowers energy consumption in heat exchanger tube and helps achieve sustainability goals. A FSCC vortex was placed inside a smooth tube that measured 1500 mm in length, 30 mm in inner diameter (Din), and 35 mm in outer diameter (Do) for testing purposes. The FSCC measured (Dtop) = 20 mm at the top and Dbase = 28 mm at the base, with a thin 0.8 mm thickness (t). In this study, the Nusselt number (Nu), friction factor (fr), and thermal performance evaluation criteria (TPEC) are examined in relation to FSCC perforations (N = 0, 2, and 3) and pitch-to-hydraulic ratios (PR = P/Din = 2.5, 3.5, 4.5, and 5.5). The effects of perforations, i.e. hole number N = 0, 2, 3 and P/Din = 2.5, 3.5, 4.5, and 5.5, are considered for the analysis. The integrated tube has higher TPEC and average Nusselt numbers as compared to the smooth tube. Additionally, it uses perforations and to look at fluctuations in the average entropy generation rate (Savg). The study found that FSCC-inserted tubes have a 9.3 and 17.9 times higher Savgf than smooth tube at Re = 32,000 and 4000, respectively, for N = 0 FSCC heat exchanger tube, but at Re = 32,000, the Savgh of FSCC is 0.4 times lower. Smooth tube improves average entropy generation (Savg), while friction flow creates irreversibility defects. Smooth tube performance in Savg is inferior, with Savgh declining with Re and N. According to the study, vortex/swirl flow, boundary layer disturbance, and fluid mixing are the main factors influencing fluid flow, which is improved by the FSCC integrated tube and improves heat exchanger performance. Nusselt number and the friction factor both decrease as perforations increase while TPEC also increases. The results suggest that the FSCC is a useful tool for improving the efficiency of tube heat exchangers. The maximum TPEC is observed around 2.44 for N = 0 at Re = 4000 and P/Din = 3.5.