Intensification of heat transfer in heater tubes of city gas stations using spiral spring inserts

In this study, the effect of turbulators (coiled wire tube insert) as a passive method for heat transfer enhancement on heater performance of Mokhtar city gate station of Yasuj city has been evaluated. To analyze the performance and the effect of geometrical parameters of turbulators and physical parameters of the flow, steady state and incompressible flow were simulated through ANSYS CFX 14.5. Shear stress transport (SST) turbulence model for modeling turbulated flow regime besides the wall has been used. Using simulation results, important performance parameters such as friction factor, Nusselt number, and thermal performance factor were calculated and deeply studied. Physical parameters of flow contain Pressure and Temperature, and geometrical parameters of turbulator include turns number, turn diameter, wire diameter and wire cross-section is studied on the heater performance. The results show that Nusselt number for the tube insert with 75.4 mm pitch with circular, square and triangular cross sections increased up to 57, 62 and 79 percent, respectively. Also, calculated mean thermal performance factor for each case was 1.038, 1.045 and 1.087, respectively. Therefore, the spiral spring inserts with triangular cross-sectional is more effective compared to others.