International Journal of Research and Scientific Innovation (IJRSI) | Volume IV, Issue IA, January 2017 | ISSN 2321–2705 www.rsisinternational.org Page 26 A Review of Forced Convection Heat Transfer and Pressure Drop in Shell and Helical Coiled Tube Heat Exchanger of Nanofluids P.C. Mukesh Kumar Faculty of Mechanical Engineering, University College of Engineering Dindigul- 624 622, Tamilnadu, India. K.Palanisamy Center for thermal and energy research, Faculty of Mechanical Engineering, M. Kumarasamy College of Engineering, Karur-639 113, Tamilnadu, India. Abstract – The purpose of the this review summarizes the recent published on the heat transfer and pressure drop in shell and helical coiled tube heat exchanger using nanoflids as working fluid. The naofluid is the colloidal suspension of nano sized particles like metal and metal oxides in some base fluid as convectional fluid like water, ethylene glycol. The forced convection heat transfer nanofluid is investigated by more researches. This paper reviews the paper published on experimental studies of forced convection heat transfer and pressure drop of nanofluids. Most of the researchers have identify a little rise in pressure drop with use of nanofluids in helical coiled tube. In order to the nanofluid are able to enhancement of heat transfer at low particle concentration. A large difference in Nusselt number was observed for more studies under laminar and turbulent flow region Keywords – Nanofluids, helical coil, turbulent flow, pressure drop, heat transfer enhancement. I. INTRODUCTION he heat transfer enhancement technology has been developed and widely applied in heat exchangers, in general the classification of enhancement of heat transfer technique can be divide in three types, like active, passive and compound technique. Active technique require an external forces like fluid vibration, electric field , surface vibration, injection and suction. Passive technique require special surface geometries like varies tube inserts, coiled tube and additives for liquids. Compound techniques are combination of any two or more techniques simultaneously to obtain enhancement heat transfer. The helical coiled tube have a wide range of application in engineering system such as power generation , nuclear reactor, process plant, heat recovery system, refrigeration, food industry. A helical coil tube is characterized by the coil diameter (D), coiled curvature radius (R), and coil pitch (b). in the case of curvature radius is constant. Helical coiled tube are efficient het transfer equipments due to their compact size and high heat transfer performance in comparison with straight tube heat exchanger. Several researches studies have been conducted to analyze the heat transfer and pressure drop of helical coiled tube heat exchanger in laminar and turbulent flow. The mostly characteristics of flow in helical coiled tube is the secondary flow induced by centrifugal force due to perpendicular to the axial fluid direction, which results in an improved fluid mixing, thus reducing the thickness of the thermal boundary layer. A. Thermo physical properties of nanoflids Heat transfer conventional fluids such as water, lubricating oil, ethylene glycol have very poor thermal conductivity compared to metal and metal oxides. The heat transfer coefficient can be improved due to the thermal conductivity solid particle to the liquid coolant. The use of solid particle as an additive suspended in to the base fluid is a technique for the heat transfer enhancement. Improve the thermal conductivity is a key idea to improve the heat transfer characteristics of convectional fluids. The enhancement of thermal conductivity of convectional fluid by the suspension of solid particles, such as 1-100nm size nano particles but large particles cause some trouble some problem such as agglomeration , clogging, erosion in the flow path. 1. Thermal conductivity The thermal conductivity is the most studied property of nanofluids. Li and Peterson [1] experimentally studies the thermal conductivity of Al 2 O 3 and CuO nanoparticles in water at volume fractions of 2, 4, 6, and 10 %. The result observed high thermal conductivity for both fluids. At 6 vol% , an increment of about 52 % in thermal conductivity was reported for CuO / water nanofluid. With Al 2 O 3 the enhancement in thermal conductivity was 30% at 10 vol %. Murshed et al. [2] investigated TiO 2 nanoparticle of rod shape and spherical shape dispersed in deionized water . They observed nearly 33% and 30% enhancements of the effective thermal conductivity for TiO 2 particle of rod shape and spherical shape nanoparticles respectively. Both particle size and shape influenced the thermal conductivity of nanofluids. Patel et al. [3] studied gold and silver (Ag) nanoparticle with thoriate and citrate as coating in water and toluene based fluids. The T