International Journal of Scientific and Research Publications, Volume 7, Issue 5, May 2017 56 ISSN 2250-3153 www.ijsrp.org Experimental Study on Helical Coil Heat Exchanger A. A. Ayare and S. D. Anjarlekar M. N. Tagare 1 and S. S. Wamane 2 Department of Mechanical Engineering 1 Associate and 2 Assistant Professor FAMT College, University of Mumbai FAMT College, University of Mumbai Ratnagiri, India Ratnagiri, India aniketayare7@gmail.com Abstract - The recovery of waste heat has been a topic of concern for large-scale industrial companies for several decades. This recovery not only makes an operation more environment friendly, but it also helps to cut costs. In addition to this, it can reduce the amount of resources needed to power a facility. Many industries have implemented different methods of waste heat recovery. One popular choice is using a heat exchanger. This paper presents the study of two types of heat exchangers: straight and helical coil tube. The helical coil heat exchanger has been experimented and analyzed on the basic of log-mean temperature difference (LMTD), heat transfer coefficient and Reynolds number. Based on the results, it is found that helical coil heat exchangers are efficient and its overall heat transfer coefficient increases with mass flow rate. Index Terms - helical coil heat exchanger, fouling, heat transfer coefficient, LMTD and Reynolds number I. INTRODUCTION he heat is a form of energy that transfers from the hot object to the cold object, and it transferred through the conduction, the convection and the radiation. The heat energy has many usages in the industry as making metals, chemicals, refining oil and processing the food. The shortage of heat energy leads to conserve or to make best use of it. In several industrial processes there is waste of energy or a heat stream that being exhausted in atmosphere. The heat exchangers plays important role to recover this heat and place it to use by heating a different stream within the process. This practice saves a lot of money in industry, as the heat supplied to other streams from the heat exchangers would otherwise come from an external source that is more expensive and more harmful to the environment. The purpose of constructing a heat exchanger is to get an efficient technique of heat transfer from one fluid to another, by direct contact or by indirect contact. In a heat exchanger the heat transfer through radiation is negligible in comparison to conduction and convection. But convection plays the major role in the performance of a heat exchanger. There are numerous applications of heat exchangers such as heat recovery systems, refrigeration, waste water treatment plants, pharmaceuticals, oil and gas industries, HVAC, food & beverage processing industries. In addition to these applications heat exchangers are also used in large scale chemical and process industries for transferring the heat between two fluids which are at a single or two states [1]. In general, the heat transfer techniques can be divided into two groups: active and passive. The active techniques need external forces like fluid vibration, electric field and surface vibration where as passive techniques requires special surface geometries like varied tube inserts. The straight tube heat exchanger has been the oldest type of heat exchanger that has been in use. The research work has been performed by various investigators on enhancing the performance of straight tube heat exchanger by changing geometric such as baffle arrangement [2], types of tube arrangement, length of the pipe etc. The main challenge in heat exchanger design is to make it compact and to get maximum heat transfer in minimum space. However, it was found that straight tube heat exchangers have restriction in terms of sizing and space which are significant parameters while designing industrial heat exchangers. In 1970 Charles Boardman and John Germer introduced helical coil tube heat exchanger as one of the best passive heat transfer enhancement techniques. The various experimental research work have indicated that helical coil tube heat exchangers are the most useful because of its spiral coil configuration which provides more heat transfer area and better flow in minimum space [3]. This configuration leads higher heat transfer coefficient as compared to straight tube heat exchanger under the same experimental conditions. II. STRAIGHT TUBE HEAT EXCHANGERS Straight tube is the type of shell and tube heat exchangers and this is one of the most popular types of heat exchanger due to its flexibility and can be used in systems with higher operating temperatures and pressures. The shell and tube heat exchanger consists of front header, rear header, tube bundle and shell. The fluid enters the tube side of the exchanger via front header and leaves the exchanger through rear header. The tube bundle comprises of the straight tubes, tube sheets, baffles and tie rods etc. to hold the bundle together. The bundle of parallel heat exchanger tubes held in place with tube sheets and placed into a shell. Figure 1 illustrate the straight tube heat exchanger where two fluids will exchange heat, one fluid flows over the surface of the tubes whereas the second fluid flows through the tubes. The fluids can be single or two phase and can flow in a parallel or a cross/counter flow arrangement. However experimental studies proven that the straight tube heat exchangers have many disadvantages such as less heat transfer efficiency and require more space [4]. The cleaning of straight tubes is difficult and fouling is often a problem when overall heat transfer coefficient is addressed. This needs periodic cleaning of the shell as well as the tubes. T