Citation: Venkatesh, B.; Khan, M.; Alabduallah, B.; Kiran, A.; Babu, J.C.; Bhargavi, B.; Alhayan, F. Design Optimization of Counter-Flow Double-Pipe Heat Exchanger Using Hybrid Optimization Algorithm. Processes 2023, 11, 1674. https:// doi.org/10.3390/pr11061674 Academic Editor: Mhamed Sayyouri Received: 22 April 2023 Revised: 28 May 2023 Accepted: 29 May 2023 Published: 31 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). processes Article Design Optimization of Counter-Flow Double-Pipe Heat Exchanger Using Hybrid Optimization Algorithm B. Venkatesh 1 , Mudassir Khan 2 , Bayan Alabduallah 3, *, Ajmeera Kiran 4 , J. Chinna Babu 5 , B. Bhargavi 6 and Fatimah Alhayan 3 1 Department of Mechanical Engineering, Annamacharya Institute of Technology and Sciences, Rajampet 516126, Andhra Pradesh, India; bhupalam.venkatesh2005@gmail.com 2 Department of Computer Science, College of Science & Arts, Tanumah, King Khalid University, P.O. Box 960, Abha 61421, Saudi Arabia; mkmiyob@kku.edu.sa 3 Department of Information Systems, College of Computer and Information Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia; fnalhayan@pnu.edu.sa 4 Department of Computer Science and Engineering, MLR Institute of Technology, Hyderabad 500043, Telangana, India; kiranphd.jntuh@gmail.com 5 Department of Electronics and Communication Engineering, Annamacharya Institute of Technology and Sciences, Rajampet 516126, Andhra Pradesh, India; jchinnababu@gmail.com 6 Department of Computer Science and Engineering, Annamacharya Institute of Technology and Sciences, Rajampet 516126, Andhra Pradesh, India; bhargavib201@gmail.com * Correspondence: bialabdullah@pnu.edu.sa Abstract: Double-pipe counter-flow heat exchangers are considered more suitable for heat recovery in the heat transfer industry. Numerous studies have been conducted to develop static tools for optimizing operating parameters of heat exchangers. Using this study, an improved heat exchanger system will be developed. This is frequently used to solve optimization problems and find optimal so- lutions. The Taguchi method determines the critical factor affecting a specific performance parameter of the heat exchanger by identifying the significant level of the factor affecting that parameter. Gray relational analysis was adopted to determine the gray relational grade to represent the multi-factor optimization model, and the heat exchanger gray relation coefficient target values that were predicted have been achieved using ANN with a back propagation model with the Levenberg–Marquardt drive algorithm. The genetic algorithm improved the accuracy of the gray relational grade by assigning gray relational coefficient values as input to the developed effective parameter. This study also demonstrated significant differences between experimental and estimated values. According to the results, selecting the parameters yielded optimal heat exchanger performance. Using a genetic algorithm to solve a double-pipe heat exchanger with counterflow can produce the most efficient heat exchanger. Keywords: double-pipe heat exchanger; genetic algorithm; gray 1. Introduction Global urbanization and a growing population have increased the demand for energy. Oil, gas, coal, etc., are fossil fuels, and their use has a negative impact on the environment. As a result, energy-saving strategies and renewable energy sources have been employed in order to address this problem [1]. As a result, an effective thermal system is being developed to reduce energy consumption. It is widely recognized that heat exchangers are essential components in a variety of industries, including electric, petroleum, electronics, chemical, and aerospace [2,3]. The design of heat exchangers has evolved significantly over time as heavy and light machinery are used in different industries. The Tubular Exchanger Manufacturers Associa- tion (TEMA) has developed and adopted standards that specify the design, construction, Processes 2023, 11, 1674. https://doi.org/10.3390/pr11061674 https://www.mdpi.com/journal/processes