Optimal Selection of a Sustainable Passive Heat Transfer Enhancement Technique for Circular Pipe Heat Exchanger Using MCDM Framework.

Circular pipe heat exchangers, widely used in process industries, rely on passive heat transfer augmentation techniques like twisted tape inserts to enhance thermal performance. The challenge lies in identifying the optimal insert design. This study applies hybrid multi-criteria decision-making (MCDM) techniques to address this challenge, aiming to identify the best twisted tape insert configuration for maximizing heat exchanger efficiency. For developing the method, twenty-one passive enhancement techniques have been identified. This study employs a holistic approach, considering eight parameters (surface–volume ratio, Nusselt number, friction factor, thermal performance factor, total investment cost, cost per efficiency and CO2 emissions) across four criteria (geometric, thermo-hydraulic, economic and environmental criteria) to optimize resource utilization while reducing environmental impact and minimizing costs. The Entropy-CRITIC (Criteria importance through inter-criteria correlation) weighing method (ECWM) was employed to find the weights of all parameters, and ranking of alternatives was done by TOPSIS (Technique of order preference similarity to ideal solution), COPRAS (Complex proportional assessment) and CoCoSo (Combined compromise solution) MCDM methods. These hybrid approaches, combining objective weighting with MCDM ranking, facilitated the identification of ideal twisted tape inserts. To ensure the robustness of the MCDM methods, sensitivity analysis, Spearman rank correlation and rank reversal techniques were employed for validation. COPRAS emerged as the most robust MCDM method, indicating cross-cut twisted tape as the optimal solution for heat transfer augmentation. This research demonstrates the effectiveness of MCDM techniques in selecting optimal sustainable passive inserts for enhancing the thermal performance of circular pipe heat exchangers. [ABSTRACT FROM AUTHOR]