Advances in computational fluid dynamics for enhanced heat transfer applications in engineering systems: a critical review and comparative synthesis

Computational Fluid Dynamics has become an important tool for evaluating heat-transfer enhancement in engineering systems where thermal performance must be balanced against pressure loss, energy consumption, and design constraints. This critical review and comparative synthesis examine published CFD investigations of selected heat-exchange applications, including shell-and-tube, double-pipe, twisted-tube, and ground-air heat exchangers. The reviewed studies include nanofluid-based enhancement, geometric modification, internal turbulators, and optimization-based design strategies. The selected literature is compared in terms of evidence for heat-transfer improvement, hydraulic penalties, numerical modeling options, validation methods, and practical applications. The synthesis shows that geometric changes and passive flow-disruption methods can yield significant thermal gains, but at the cost of higher-pressure losses. Nanofluids are also a potential means of further improving heat transfer with relatively minor structural modification, but their long-term stability, fouling characteristics, and pumping needs are still practical issues to be addressed. The comparison also shows that no single enhancement method is always best; performance depends on the exchanger configuration, operating conditions, flow regime, and design objectives. The review highlights the need for consistent thermal–hydraulic performance assessment, better experimental validation, and more attention to manufacturability and long-term operation. It concludes with application-oriented guidance and future priorities for reliable, energy-efficient CFD-assisted thermal-system design.