Determining the Best Passive Heat Transfer Enhancement Technique in Circular Pipe Heat Exchangers with the MCDM Technique

Heat transfer enhancement techniques are extensively used in circular pipe heat exchangers to reduce their size and improve heat transfer. Heat transfer enhancement techniques usually include passive, active, and compound heat transfer enhancement. Unlike active techniques, passive techniques don’t require external power to improve heat transfer. Passive techniques include twisted tapes, conical inserts, coils, nozzles, baffles, etc. Twisted tapes are studied extensively among all passive techniques for their lower manufacturing, operating, and maintenance cost and better thermal performance than others. Research is done mainly on finding new techniques and improving present passive techniques, no effort has been made to find the best passive techniques. The present study should determine the best passive heat transfer enhancement techniques for circular pipe heat exchangers using the MCDM technique, applied with technical and economic criteria for twisted tapes. MCDM (Multi-Criteria Decision Making) techniques are used to find the best passive heat transfer enhancement technique. Nusselt number, friction factor, Reynolds number, the surface to volume ratio, and cost to thermal performance are criteria to rank among each other. Our study has shown that twisted tape with the peripheral rectangular cut is the best possible twisted tape among the chosen ones for passive heat transfer analysis.