OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 7 5 Numerical and experimental investigation of heat transfer augmentation in roughened pipes Siddhanath Nishandar 1, a, Ashok Pise 1, b, Pramodkumar Bagade 2, c, * 1 Department of Mechanical Engineering, Government College of Engineering, Karad, Shivaji University, Kolhapur, Maharashtra 445414, India 2 Department of Mechanical Engineering, TSSM’s Bhivarabai Sawant College of Engineering and Research (BSCOER), Narhe, Pune, Maharashtra 445414, India a https://orcid.org/0000-0001-6190-3412, siddhant.nishandar04@gmail.com; b https://orcid.org/0009-0003-0276-8996, ashokpise@gmail.com; c https://orcid.org/0000-0002-4069-1542, pramodbagade@gmail.com Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2025 vol. 27 no. 3 pp. 87–107 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2025-27.3-87-107 ART I CLE I NFO Article history: Received: 23 June 2025 Revised: 04 July 2025 Accepted: 10 July 2025 Available online: 15 September 2025 Keywords: Heat transfer enhancement Surface roughness Turbulent kinetic energy (TKE) Pulsating flow Turbulent flow Nusselt number (Nu) ABSTRACT Introduction. In many technical applications, such as thermal energy systems, chemical processing, power production, and HVAC, efficient heat transfer (HT) is essential. Research on improving HT performance in circular pipes is still crucial, especially when it comes to changes that cause thermal boundary layers to be disrupted and turbulence to grow. Purpose of the work: The purpose of this work is to thoroughly examine how convective heat transfer can be improved in circular pipes with purposefully roughened surfaces. It focuses on how surface roughness, flow pulsations, Reynolds number (Re), and heat flow rate (Q) affect thermal performance. Methods of investigation. A combination of experimental and numerical methods is employed to assess the thermo-fluid dynamics inside the pipe. Lab-scale experiments and computational fluid dynamics (CFD) simulations are used to investigate temperature distribution, velocity and pressure fields, turbulent kinetic energy (TKE), vorticity, eddy viscosity, local heat transfer coefficient (h), and Nusselt number (Nu). Additionally, sinusoidal pulsations are introduced at the inlet and the outlet, with regular oscillations in frequency (f) and amplitude (A), over a turbulent flow range (6,753 ≤ Re ≤ 31,000). Results and discussion. The results show that surface roughness enhances HT by significantly increasing turbulence and disrupting the thermal boundary layer. TKE becomes a significant factor when there is a strong correlation between higher HT coefficients and rising turbulence intensity. HT performance is further improved by introducing flow pulsations; downstream pulsation increases Nu by 20–22% and upstream pulsing by 16–19%. The outcomes demonstrate how effectively controlled flow pulsations and surface roughness combine to optimize heat transfer. This collaborative approach holds great potential for compact and highly efficient thermal system designs in industrial environments. For citation: Nishandar S.V., Pise A.T., Bagade P.M. Numerical and experimental investigation of heat transfer augmentation in roughened pipes. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2025, vol. 27, no. 3, pp. 87–107. DOI: 10.17212/1994-6309-2025-27.3-87-107. (In Russian). ______ * Corresponding author Bagade Pramodkumar M., Ph.D. (Aerospace Engineering), Professor Department of Mechanical Engineering, TSSM’s Bhivarabai Sawant College of Engineering and Research (BSCOER), Narhe, Pune, 445414, Maharashtra, India Tel.: +91 9075279575, e-mail: pramodbagade@gmail.co Introduction To improve heat exchanger performance while lowering size and operating costs, several tactics have been investigated. These tactics are typically divided into two categories: passive and active. Passive methods – such as the use of finned or spirally roughened tubes – decrease the thickness of the thermal boundary layer and improve heat transfer (HT) by creating turbulence close to the tube wall. In recent years, these methods have drawn more attention. Active approaches, on the other hand, make use of external energy sources and include strategies like fluid pulsation, jet impingement, mechanical vibration, and the use of electrostatic fields to boost HT efficiency.
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