IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 04, 2015 | ISSN (online): 2321-0613 All rights reserved by www.ijsrd.com 1948 A Review on Investigation of Performance of Pipe in Pipe Helically Coil Heat Exchanger Ritesh Kumar 1 Dr. Manish S. Deshmukh 2 Kamal Kumar Ghosh 3 1 PG Student 2 Professor 3 Associate Professor 1,2 Rajarshi Shahu College of Engineering, Tathaware, Pune, Maharashtra, India 3 College of Military Engineering, Pune, Maharashtra, India Abstract— Enhancing the heat transfer by the use of helical coils has been studied and researched by many researchers, because the fluid dynamics inside the pipes of a helical coil heat exchanger offer certain advantages over the straight tubes, shell and tube type heat exchanger, in terms of better heat transfer and mass transfer coefficients. This configuration offers a high compact structure and a high overall heat transfer coefficient; hence helical coil heat exchangers are widely used in industrial applications. Convective heat transfer between a surface and the surrounding fluid in a heat exchanger has been a major issue and a topic of study in the recent years. In this particular study, an attempt has been made to experimental work of various parameters like radius of tubes, pitch of coil, pitch circle diameter, number of turns of helical coil, flow rate and temperature that affect the effectiveness of a heat exchanger and increases heat transfer rate at two different flows (parallel and counter-flow)on the total heat transfer from a helical tube, where the cold fluid flows in the outer pipe and the hot fluid flowing in the inner pipes of the pipe in pipe helical coiled heat exchanger. This paper focus on the review on helically coiled heat exchanger. Key words: Helical Coil Heat Exchangers, Parallel Flow And Counter Flow, Coil Configuration, CFD I. INTRODUCTION Heat exchangers serve a straight forward purpose controlling a system’s or substance’s temperature by adding or removing thermal energy. Although there are many different sizes, levels of sophistication, and types of heat exchangers, they all use a thermally conducting element usually in the form of a tube or plate to separate two fluids, such that one can transfer thermal energy to the other. Home heating systems use a heat exchanger to transfer combustion - gas heat to water or air, which is circulated through the house. Power plants use locally available water or ambient air in quite large heat exchangers to condense steam from the turbines. Many industrial applications use small heat exchangers to establish or maintain a required temperature. In industry, heat exchangers perform many tasks, ranging from cooling lasers to establishing a controlled sample temperature prior to chromatography. A. Helical Coil Heat Exchanger Helically coiled tubes fig-1 can be found in many applications including food processing, nuclear reactors, compact heat exchangers, heat recovery systems, chemical processing, low value heat exchange, and medical equipment. Curved tubes are of interest to the medical community as blood flow occurs in many arteries that are curved. Helical coils are very alluring for various processes such as heat exchangers and reactors because they can accommodate a large heat transfer area in a small space, Fig. 1: Diagram of Helical Coil with high heat transfer coefficients and narrow residence time distributions. Due to the extensive use of helical coils in these applications, knowledge about the pressure drop, flow patterns, and heat transfer characteristics are very important. Pressure drop characteristics are required for evaluating pump power required to overcome pressure drops to provide the necessary flow rates. These pressure drops are also functions of the curvature of the tube. The curvature induces secondary flow patterns perpendicular to the main axial flow direction. Typically, fluid in the core of the tube moves towards the outer wall, then returns to the inner portion of tube by flowing back along the wall, as shown in figure-2. Secondary flow can be expected to enhance heat transfer between the tube wall and the flowing fluid. Another advantage to using helical coils over straight tubes is that the residence time spread is reduced, allowing helical coils to be used to reduce axial dispersion in tubular reactors. Thus, for design of heat exchangers that contain curved tubes, or helically coiled heat exchangers, the heat transfer and hydrodynamic characteristics need to be known for different configurations of the coil, including the ratio of tube radius to coil radius, pitch, and Reynolds and Prandtl numbers and Dean Number (De). Fig. 2: Secondary flow for low and high Dean Numbers The fluid motion in curved pipes was first observed by Eustice in 1911. Since then numerous studies have been reported on the flow fields that arise in curved pipes (Dean, 1927, 1928; White, 1929; Hawthorne, 1951; Horlock, 1956;