Experimental investigation of heat transfer enhancement in a double-pipe heat exchanger using solid rod inserts with crude oil and gas condensate
Annotatsiya
Heat exchangers are crucial components in many industrial applications, ensuring efficient thermal energy transfer during heating, cooling, evaporation, and condensation. However, conventional tubular heat exchangers operating in laminar or transitional flow regimes often exhibit low thermal performance. To increase the turbulence of the flow, the main influencing design parameters are the diameter, length and roughness of the pipe. This study experimentally investigates the enhancement of heat transfer in a concentric double-pipe heat exchanger through the insertion of stainless-steel rods (diameters: 10 mm, 12 mm, and 15 mm) into the inner tube (20 mm ID). The working fluids were crude oil and gas condensate, heated by gas condensate steam at 120 °C. Experiments were conducted at mass flow rates of 2–14 kg/min, corresponding to Reynolds numbers ranging from 372 to 4427 for crude oil and 422 to 33,433 for gas condensate, thereby covering laminar, transitional, and turbulent flow regimes. The results show a pronounced improvement in heat transfer performance with rod inserts. For crude oil, the 15 mm rod increased the outlet temperature from 70 °C (plain tube) to 79 °C, while the overall heat transfer coefficient (K) increased from 39 W/(m2·K) to 220 W/(m2·K), representing an enhancement of 464%. For gas condensate, the 15 mm rod raised the outlet temperature from 76 °C to 84 °C, while K increased from 179 W/(m2·K) to 1173 W/(m2·K), corresponding to an improvement of 555%. These results confirm that rod inserts significantly intensify turbulence and convective mixing, reduce the hydraulic diameter, and thus enhance heat transfer efficiency. This work provides clear quantitative evidence that simple rod inserts can substantially improve the performance of tubular heat exchangers, with strong potential for application in petroleum refining, chemical, and energy industries where energy efficiency and compactness are critical.