Thermal Analysis Of Counter Flow Shell And Tube Heat Exchanger

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1 Thermal Analysis Of Counter Flow Shell And Tube Heat Exchanger Risal K K 1 Nikhil T C 4 Binto anto 7 Siril Sunny 2 Adarsh Shalish 5 Texo Jose 8 Assistant Professor Akshay V 3 Swamin P V 6 Abstract: Shell and Tube Heat Exchanger in which it is Fixed Tube-sheet and Counter Flow Type Heat Exchanger. Here, Shell side fluid is cold water and tube side fluid is hot air. Cold water is cold fluid And hot air is hot fluid. We do Thermal Designing and Analysis of STHX due to the problem of Large Pressure Drop at shell side, Large Pressure Drop at tube side, Less Heat Transfer rate and Cost is very high and also will do analysis of corrugated tube and compare with existing plain tube. We are designing model of shell and tube heat exchanger in which plain and corrugated tube is used e after e and taking reading for thermal analysis calculati and then compare Experiment Result to CFD Analysis result for validati. In Computatial Fluid Dynamics (CFD) Analysis Software use Solid Works 2013 for Geometry &Modeling,ICEM CFD (ANSYS 15) for Meshing and Fluent for Analysis. Keywords: heat transfer rate, CFD, shell and tube heat I. INTRODUCTION Heat exchangers are e of the mostly used equipment in the process industries. Heat exchangers are used to transfer heat between two process streams. One can realize their usage that any process which involve cooling, heating, cdensati, boiling or evaporati will require a heat exchanger for these purpose. Process fluids, usually are heated or cooled before the process or undergo a phase change. Different heat exchangers are named according to their applicati. For example, heat exchangers being used to cdense are known as cdensers, similarly heat exchanger for boiling purposes are called boilers. Performance and efficiency of heat exchangers are measured through the amount of heat transfer using least area of heat transfer and pressure drop. A more better presentati of its efficiency is de by calculating over all heat transfer coefficient. Pressure drop and area required for a certain amount of heat transfer, provides an insight about the capital cost and power requirements (Running cost) of a heat exchanger. II. COMPUTATIONAL MODEL The computatial model of an experimental tested Shell and Tube Heat Exchanger(STHX) is shown in figure,and the geometry parameters are listed in Table. The whole computati domain is bounded by the inner side of the shell and everything in the shell ctained in the domain. The inlet and outlet of the domain are cnected with the correspding tubes. Table 1 Heat exchanger length, L 1405mm Shell inner diameter, Di Tube outer diameter, do Number of tubes, Nt 109 Number of baffles. Nb 4 Central baffle spacing, B Pitch Number of passes mm 9.525mm 281mm 14mm

2 1405mm lg. We have also modeled internal and external fluids. Since this is a symmetrical type model we have shown symmetrically cut secti model and this will reduce computati time without affecting the results. Figure 1 III. EXPERIMENTAL RESULTS Measurements are taken ly after the temperatures attain steady values. Experiments are cducted for five different flow rates through the coil and for three different values of temperature at the inlet of the helical pipe. During the course of each set of experiments, the flow rate through the shell side is kept cstant, which ensures a cstant heat transfer coefficient the shell side. The experiment is carried out by changing the flow rate through the tube. Once a steady state is attained, values of flow rates of the hot and cold fluids, temperatures at the inlet and exit of the hot and cold fluid, and the power input to the heater and the pump are noted. result Fig 2 Mesh Specificatis Temperature of hot Inlet T=403k Temperature of hot outlet T=320k Temperature of cold inlet T=301k Temperature of cold outlet T=305k inside diameter of shell=251.5mm baffle space=281mm number of passes=1 number of tube=109 outside diameter of tube=9.525mm pitch=14mm length of tube=1405mm Mass flow rate of hot fluid, Mh=0.3216kg/sec Mass flow rate of cold fluid, Mc=1.25kg/sec Cpc =4178KJ/Kg K Cph=1009KJ/Kg K Effectiveness Σ = IV. SIMULATION OF SHELL AND TUBE HEAT EXCHANGER This is Ansys design modular envirment. Here the physical geometry of the heat exchanger can be drawn or imported from another CAD software SOLIDWORKS.The heat exchanger modeled here ctains 109 tubes each Effectiveness Σ = Fig 3 Result V. BAFFLES One of the most important parts in shell and tube heat exchangers are the baffles. Baffles serve mainly two functis: Fixing of the tubes in the proper positi during assembly and preventi of tube vibrati caused by flow-induced eddies. Guidance of the shell-side flow across the tube field, increasing the velocity and the heat transfer coefficient

3 To find the effect of baffle we also simulated the cditi without baffles.the simulated results without baffle is shown below. A. Design of plain tube Initially we designed a single plain tube for simulati. Fig 5 single plain tube Fig 4 result without baffles Effectiveness Σ = VI. CORRUGATED TUBES Corrugated Tube Heat Exchangers are shell and tube heat exchangers which use corrugated tubes instead of plain tubes. Development Corrugated Tubes take the best features of both the plain tube and the plate heat exchanger. Corrugated tube is produced by indenting a plain tube with a spiral pattern. Plain tubes offer the best geometry to withstand pressure but the worst for heat transfer due to rapid build-up of boundary layer. Plates in a plate heat exchanger induce local turbulence to increase heat transfer coefficient but is limiting in terms of operating pressures and temperatures due to elastomer gaskets. Also, the relatively narrow gap limits its use to fluids without large fibres and particulates. By choosing the depth, angle and width of the indentati carefully, the rate of decrease in boundary layer resistance can exceed the rate of increase in pressure loss. Inorder to find the effect of corrugated tube we csidered a single tube to represent the entire tubes in the heat exchanger. we are giving input cditi overall heat transfer coefficient h i= w/m 2 K determined by calculati. Fig 6 meshed view of single plain tube Effectiveness Σ = Fig 7 simulati result of plain tube

4 B. Design of corrugated tube We designed a single corrugated tube for simulati. VII. COMPARISON Table 2 Type Temp eratur e (Hot In) Tem pera ture (Col d In) Temperat ure (Hot out) Tem pera ture (Col d out) Effect ivene ss Fig 8 meshed view of corrugated tube Fig 9 enlarged view of mesh Experim ental Without baffles Single tube Single corrugate d tube VIII. CONCLUSION From this we could cclude: When taking effect of corrugati in tube of ordinary shell and tube exchanger,it increases its effectiveness than plane tubes By our project we could see how baffles effects the heat transfer in heat exchangers. adapting both baffles and corrugati we can increase the effectiveness of a heat exchanger Efficiency and effectiveness has increased in corrugated tube compare to plain tube from CFD result. From above result we say that our design is safe to help to increase performance of heat exchanger. Fig 10 simulati result of corrugated tube Effectiveness Σ =

5 REFERENCES 1. Hari Haran,Ravindra Reddy & Sreehari: Thermal analysis of STHX using C and Ansys. (IJCTT) volume 4 Issue 7,July Hetal Kotwal, D.S Patel: CFD Analysis of Shell and Tube Heat Exchanger- A Review (IJESIT) Volume 2, Issue 2, March Gajanan P Nagre, A. V. Gadekar: Design and Thermal Performance Analysis of Shell and Tube Heat Exchanger by Using CFD. (IJSR) ISSN (Online): Index Copernicus Value (2013): 6.14 Impact Factor (2014): Durgesh Bhatt, Priyanka M Javhar : Shell and Tube Heat Exchanger Performance Analysis. (IJSR) ISSN (Online): Impact Factor (2012): Jiyuan tu text book Computatial fluid dynamics- A practical approach. 6. John D. Anders book Computatial fluid dynamics- The basics with applicatis