A Comprehensive Review on the Performance and Stability of Nanofluids in Plate Heat Exchangers

In the last two decades, there has been a significant focus on improving the efficiency of heat exchangers by using nanofluids. Nanofluids have superior thermal conductivity and slightly increased specific heat. This review encompasses the studies conducted on improvements in the heat transfer efficiency of plate heat exchangers (PHE) for various nanoparticles (metallic, metal oxides, nonmetallic, hybrid) by different methods (experimental, empirical, and numerical analysis). Nanofluids have been found to have marginally increased viscosity and density and can cause little increase in pumping power. This review includes studies on increased power consumption in using nanofluids in PHE. Though nanoparticles are ultrafine particles, sedimentation and coagulation may affect the heat transfer after prolonged usage. This review includes studies conducted on sedimentation and coagulation of nanoparticles in PHE. Nanofluids may become unstable after continuous use, so this review explores the findings on the stability of nanofluids and various methods of increasing the stability of nanofluids, such as sonication and surfactants in PHE. This review also covers studies of nanofluids using artificial intelligence (AI) and machine learning (ML). By this review, it has been found that nanofluids undoubtedly increase heat transfer efficiency. However, the effects of coagulation, sedimentation, and stability over long-term use cannot be completely ruled out. Hence more comprehensive research is needed to assess the stability of nanofluids for prolonged use. Future research using AI and ML can help in developing commercially economical models that can work for a substantial period.