A Review of Research in Thermal Engineering.Study of Various Factors and Parameters Involved in Usage of different types of turbulators in heat exchangers Manish Sanserwal University Institute of Engineering and Technology Kurukshetra University, Kurukshetra, Haryana, India Mayank Bhardwaj University Institute of Engineering and Technology Kurukshetra University, Kurukshetra, Haryana, India Abstract - Great efforts has been put forthfor developing efficient heat transfer enhancement devices with several designs in order to enhance the turbulence, enhance the friction factor, separation of boundary layer and thereby improving the heat transfer efficiency leading a way to improve the efficiency of heat exchanger without altering its size and simultaneously increasing the heat transfer surface area. Among various turbulator designs current paper emphasizes three specific designs viz. nozzle turbulator, conical wire coils, perforated conical ring and (non-perforated) conical rings and slight variations in the parameters that were considered when these were employed in different investigations. Keywords - Heat transfer, conical wire coil, Nozzle, Perforated conical ring, turbulator, turbulent flow, pressure drop, Heat transfer enhancement, Heat exchanger, Friction factor, Thermal performance factor. I. INTRODUCTION Techniques for heat transfer enhancement in heat exchangers is a subject of great importance in fields such as automotive, refrigeration and process industries because of reduction of the heat transfer surface area for a given application. Such techniques generate a great scope for various analytical and experimental investigations in Heat Enhancement. These techniques can be categorized as Active, Passive and Compound. Whereas, the active techniques require external power viz. surface vibration, fluid vibration, injection, suction, and electric or acoustic fields, the passive techniques employ special surface geometries, partial obstructions, perforations etc. for heat transfer enhancement viz. extended surfaces, rough surfaces, twisted tapes, helical springs, perforated conical rings, conical spring, nozzle inserts etc., which also forms the category of turbulators. Typically, the turbulators increase fluid mixing, by increasing turbulence or by limiting the growth of fluid boundary layers close to the heat transfer surfaces. Several enhancement techniques have been used till date to significantly enhance the performance of heat exchangers. These intriguing techniques are not germane to typical heatexchangers but also find there use from industrial boilers to space vehicles. Numerous amounts of research works has been performed regarding such techniques leaving no page unturned and no fact uncovered. Yakut et al.[3] investigated the role of conical-ring turbulator on heat transfer enhancement and friction factor by judging fluid flow in tubes when a uniform heatflux was maintained varied pitch ratios were used.It was observed that the turbulator with the smallest pitch ratio offered highest heat transfer enhancement and thermal performance factor. Yakut and Sahin[4] showed that the conical-ring also producedthe vortices in the tubeflow. Promvonge[5]investigated the effect ofthe conical ring turbulator arrangements (converging conical ring - CRarray, diverging conical-ring - DRarrayandconverging–diverging conical-ring - CDR array) on the heat transfer rate and frictionfactor. The results revealed that the conical-ring with the DR arrayprovided superior thermal performance compared to thosewith the CRand CDR arrays. ,QWHUQDWLRQDO-RXUQDORI,QQRYDWLRQVLQ(QJLQHHULQJDQG7HFKQRORJ\,-,(7 9RO,VVXH$SULO  ,661ｱ