A comprehensive review on the current technologies and recent developments in high-temperature heat exchangers

High-temperature heat exchangers are extensively studied today due to their benefits for industrial processes. In most cases, there is a threshold for the maximum operating temperature of heat exchangers. Beyond this temperature level, special design and material considerations are required. This threshold is 600 degrees C today, which is higher than in the past due to recent advances in heat transfer and materials. This study presents extensive information about various designs of high-temperature heat exchangers, their materials and heat transfer fluids, and the most significant technical issues and scientific gaps in this field. The aim is to shed light on the pathway to improving high-temperature heat exchanger efficiency, economic feasibility, and safety. The research survey shows that i) molten salts, liquid metals, helium, supercritical carbon dioxide, etc. are the most appropriate heat transfer fluids for high-temperature heat exchangers; ii) shell and tube, plate, plate and fin, helical coil, finned tube, printed circuit, double-pipe, and bayonet tube heat exchangers are the most commonly used configurations for high-temperature applications; and iii) iron-and nickel-based alloys, and ceramics are the most commonly used materials. The critical issues in high-temperature heat exchangers are corrosion, material degradation over time, quality degradation, and limited lifetime. The main benchmarks needed for high-temperature heat exchanger design are fluid types, working conditions, required heat transfer rate, and costs. The study represents a brief yet informative state-of-the-art and discusses the gaps for each of these parameters, providing readers with a clear line of future research.