ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The influence of liquid hydrocarbon flow recirculation on the efficiency of heat exchange in a shell-and-tube apparatus

Oybek Ismoilov, Rustam Yusupov, Fozilbek Shomansurov, Kumush Akhmedova, Isroiljon Abdurakhmanov, and Mavluda Baltabayeva

Institute of General and Inorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan

E-mail: ismoilovnmpi@mail.ru

Received: 14 May 2025  Accepted: 3 August 2025

Abstract:

Enhancing the thermal efficiency of shell-and-tube heat exchangers is critical in the optimization of hydrocarbon processing systems. This study presents an experimental investigation into the impact of liquid hydrocarbon recirculation on heat transfer performance within a shell-and-tube apparatus. The system comprises a 1-m-long shell (diameter 76 mm) containing seven inner tubes (diameter 15 mm), with feed and recirculation lines of 20 mm and 10 mm, respectively. Experiments were conducted at a feed rate of 10 L/min and an initial temperature of 20 °C, under varying recirculation ratios ranging from 5 to 30%. Results demonstrate that increasing the recirculation ratio leads to significant improvements in heat transfer dynamics. Specifically, a 30% recirculation rate increased the outlet temperature of oil by up to 16 °C and gas condensate by up to 18 °C. These changes were accompanied by a reduction in kinematic viscosity (up to 28.1% for oil and 25.4% for condensate) and a slight shift in fluid density. Enhanced hydrodynamic conditions contributed to a measurable rise in the convective heat transfer coefficient (5.49% for oil and 6.38% for condensate), with the overall heat transfer coefficient (K) increasing by up to 14%. The findings highlight the effectiveness of internal recirculation as a practical strategy for intensifying heat exchange processes in compact hydrocarbon systems, offering potential for energy savings and process efficiency improvements in industrial applications.

Keywords: Crude oil; Gas condensate; Recirculation ratio; Viscosity; Density; Heat transfer coefficient; Heat exchange efficiency; Overall heat transfer rate

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04374-0

Chemical Papers 79 (12) 9099–9110 (2025)