Comparison of Epoxy Composites using E-Glass/Carbon Reinforcements 1 M.Arun Kumar, 2 K.Dinesh Kumar, 3 S.Karthick 1 Assistant Professor, Department of Mechanical Engineering, JIT Thopur, India 2,3 UG Students, Department of Mechanical Engineering, JIT Thopur, India Abstract: The computational fluid dynamics (CFD) is the science of predicting fluid flow, heat transfer, mass transfer, chemical reactions, and related phenomena by solving the mathematical equations which govern these processes using a numerical process. Various researches are going on to avoid scaling (or) fouling formation in shell and tube heat exchanger and increase the rate of heat transfer. Here we are introduce our concept to avoid scaling by wounding the copper coil on the shell and tube in the heat exchanger. Different case of heat exchangers are analyzing by CFD simulation software and comparing the result of rate of heat transfer.the copper coil made with sharp edges wound on the tube. So, it reduce the fouling formation 85-90% and enhance the rate of heat transfer when compare to other type of heat exchanger. Keywords: CFD simulation software, copper coil (plain and sharp), Shell and Tube type Heat exchanger. I. INTRODUCTION Computational Fluid Dynamics (CFD) as it is popularly known is used to generate flow simulations with the help of computer. CFD involves the solution of the governing loss of fluid dynamics numerically. The complex sets of partial differential equation of solved on the geometrical domain divided into small volumes, commonly known as a mesh or grid. Different diameters of tube and different mass flow rates are considered to examine the optimal flow distribution and this problem has been subjected to effect of materials (Aluminum, copper and alloys) used for tube manufacturing on heat transfer rate[1].to verify the shell and tube heat exchanger designed with the use of the Kern s method by the use of CFD. It is used to study the Temperature and velocity profiles through the tubes and the shell [2]. Using the ANSYS software, the thermal analysis of shell and tube heat exchanger is carried out by varying the tube materials. The Tubular heat exchanger can be designed for high pressures relative to environment and high pressure differences between the fluids. It is used primarily for liquid to liquid [3].The heat transfer enhancement in a heat exchanger tube by installing seven different baffle arrangements. The rate of heat transfer is maximum for rectangular and triangular baffle because behind maximum heat transfer rate was that due to use of baffles, turbulence was increased as they allow more mixing of fluid layers and resulted in increase of heat transfer through the heat exchanger tube [4]. The steady of increase in computing power has enable model to react for multiphase flows in realistic geometry with good resolution in [5]. This system is used to study a fin-and-tube heat exchanger. The purpose of the work was investigate the possibilities of eventually using CFD calculations for design of heat exchangers instead of expensive experimental testing and prototype production. Here created a model of a two-row fin and tube heat exchanger by using open source Salome software in [6]. Introducing continuous helical baffles in the shell side of the heat exchanger and small corners at variable angles of the liquid flow are the result of introduction of segmental baffles which improves heat transfer and huge decline in pressure thus increasing the fouling resistance in [7].The optimum pin shape based on minimum pressure drop and maximizing the heat transfer across the automobile engine body. The results indicate that the drop shaped pin fins show improved results on the basis of heat transfer and pressure drop by comparing other fins. The reason behind the improvement in heat transfer by drop shape pin fin was increased wetted surface area and delay in thermal flow separation from drop shape pin fin in [8].The phenomenon of forced convection with turbulent flow of industrial processes is complicated to develop analytically. The only key 1
to the problem is empirical models and numerical solutions. The heat transfer coefficient (h) and friction factor are very important parameters for fluid flow systems due to their use in determining the heat transfer rate and the pressure drop of the system respectively. Then CFD simulation compared with experimental data for air flow [9]. Heat transfer enhancement by Plain and curved winglet type vertex generators with punched holes, the flow resistance is also lower in case of curved winglet type than corresponding plain winglet vertex generators (VGs). The best results for heat transfer enhancement is obtained at high Reynolds number values (Re >10000) by using VGs. This work presents a numerically study on the mean nusselt number, friction factor and heat enhancement characteristics in a rectangular channel having a pair of winglet type VGs under uniform heat flux of 416.67 w/m 2. The result indicate the advantages of using curved winglet VGs with punched holes for heat transfer enhancement [10].Comparative study between Helical coil and Straight tube heat exchanger, here present two conditions are, In the first condition- When cold water mass flow rate is constant and hot water mass flow rate increased the effectiveness decreases. Second condition-increase in cold water mass flow rate for constant hot water mass flow rate in increase in effectiveness.helical coil counter flow is most effective in all these conditions and straight tube parallel flow heat exchanger is least effective. Because the helical coil tube heat exchanger, the increased heat transfer coefficients are a consequence of the curvature of the coil, which induces centrifugal force to act on moving fluid, resulting in the development of secondary flow. Due to the curvature effect, the fluid streams in the outer side of the pipe moves faster than the fluid streams in the inner side of pipe in [11]. II. GEOMETRICAL MODELING AND MESH GENERATION A. Methodology: clean up tool.after cleaning up the geometry surface mesh is generated in ANSA tool itself. All the surfaces are discredited using tri surface element.as the geometry has some complicated and skewed surfaces tri surface elements are used to capture the geometry. Volume mesh is generated in T- Grid which is a robust volume mesh generator. Volume is dicretized using tetrahedron.each and every cell centroid is the co-ordinate at which the navier-stokes system of equations are solved. ANSYS-FLUENT was used as the solver. Here the fluid flow is assumed to be three dimensional and turbulent.afterselection of turbulence model boundary conditions are specified. Fluent has capability to store value of physical parameters for any point in the domain for analysis. Seven points were created to store the value of physical parameters such as temperature, velocity, and pressure. FLUENT is now ready to simulate flow problem. Finally, post processing was done for result analysis. B. Geometric Modeling: Geometric model is generated in SOLIDWORKS which is very popular modeling software. The generated model is exported to the further process in the form of.iges as it is a third party format which can be taken into any other tools. Here, Two type of copper coil is used (sharp and flat edge) to create some kind of localized suction in between the copper coils due to the condensation process. So, it avoids the scale or fouling formation. The Sharp edge copper coil is more efficient when compared with the Flat edge copper coil. C.Meshing Of CFD Domain: After making the geometry of the domain, next step is to mesh the domain. The CFD tool was used to create the fine mesh quality. In considering case-1, case-2 (sharp grooves) and case-3 (plain grooves), the surface and volume mesh is generated with 5.25 and 18.89 lakhs, 5.09 and 18.96 lakhs,4.27 and 17.24 lakhs respectively. This mesh contains tetrahedral cells having triangular faces at the boundaries are shown in fig-1,2,3.the mesh details are given below For CFD simulation, first of all, the geometry of the shell and tube heat exchanger was created by using SOLIDWORKS. The geometry of the heat exchanger tube is in 3D view. After the geometry creation, Extracting the fluid region is the next step in which all the surfaces, which are in the contact of fluid are taken alone and all other surfaces are removed completely. To keep the domain air /water tight some extra surfaces are created. This clean up is done in ANSA meshing tool which is very robust 2
MODIFICATION-1 MESH DETAILS: MO DEL SURFACE MESH Q uality Volume MESH Q uality BASE CASE 525670 0.6 1889715 0.8499 Figure-2 Shell and tube heat exchanger with sharp edged grooves in meshed condition MO DIFICA TIO N 1 (SHARP GRO OVES) 509450 0.6 1896024 0.8599 This structure shows the layout of shell and tube heat exchanger with wounding of sharp edged grooves in meshed condition. MO DIFICA TIO N2 ( PLAIN GRO OVES) 427000 0.6 1724411 0.9324 MODIFICATION-2 BASE CASE Figure-3 shell and tube heat exchanger with plain edged grooves in meshed condition This structure shows the layout of shell and tube heat exchanger with wounding of plain edged grooves in meshed condition. Figure-1Base case of shell and tube heat exchanger This structure shows the general layout of shell and tube heat exchanger in meshed condition by using ANSA tool. III. Boundary Conditions: After mesh generation, boundary condition are defined for CFD domain as shown in table 1. Specify boundary condition icon is used to create boundaries. In FLUENT launcher, both fluid and solid can be defined.generally, the copper materials used in this analysis. The fluid used in this analysis is water vapour. The material and fluid properties are mentioned in table 2. Table 1: Fluid and Wall boundary conditions Steam and coolant water Fluid zone Tube thickness and cop Solid zone wire Coolant inlet Velocity inlet with vary velocity 3
Coolant outlet Steam inlet Steam outlet Coolant tube wall Shell wall Pressure outlet Mass flow inlet with mass fl rate 0.5of 0.5 kg/s Pressure outlet No slip and conduction h transfer No slip and adiabatic wall Table 2: Fluid and Solid properties considered for analysis Fluids a Solids Density Properties IV. GOVERNING EQUATIONS OF FLUID DYNAMICS The basic governing equations 7.1 7.4, which describe the fluid dynamics, are used to solve the steam and water flow. The energy equation 7.5 was used to define the conductive heat transfer across the fluid through the solid region. Conservation of Mass + div( (7.1) Specific heat Kg/m 3 W/mK J/kg-K Steam 0.598 1858.68 0.0261 Water 998.2 4182 0.6 Steel 8030 502.48 16.27 Copper 8978 381 387.6 Conservation of X Momentum + div ( + div( S Mx (7.2) Conservation of Y Momentum + div ( + div ( S My (7.3) Conservation of Z Momentum Thermal conductivity +div ( +div ( S Mz (7.4) Conservation of Energy Internalenergy: (7.5) +div( ( )+ A. EVAPORATION-CONDENSATION MODEL The evaporation-condensation model is a mechanistic model with a physical basis. It is available with the mixture and Eulerian multiphase models. The liquidvapour mass transfer (evaporation and condensation) is governed by the vapour transport equation v)+ v v )=m l v m v l Where, v Vapour phase, - vapour volume fraction, v vapour density, v - vapourphasevelocity.m l v andm v l are the rates of mass transfer due to evaporation and condensation, respectively.these rates use units of kg/s/m 3. As shown in the right side of Equation 5.6, ANSYS FLUENT defines positive mass transfer as being from the liquid to the vapour for evaporation-condensation problems. Based on the following temperature regimes, the mass transfer can be described as follows, If T>T sat Evaporation =m l v coeff*α l ρ l (T-T sat ) / T sat If T<T sat Condensation=m v l coeff*α v ρ v (T-T sat ) / T sat Coeff* is a coefficient (β) that needs to be fine tuned and interpreted as a relaxation time. α and ρ are the phase volume fraction and density respectively. The source term for the energy equation can be obtained by multiplying the rate of mass transfer by the latent heat.consider the Hertz Knudsen formula, which gives the evaporation - condensation flux based on the kinetic theory for a flat interface: dp / dt = L/T(v g -v l ) The heat flux has units of kg/s/m 3. P represents the partial pressure of the vapour at the interface on the gas side in KN/m 2 and T is the temperature in K. The coefficient β is the accommodation coefficient that shows the portion of vapour molecules going into the liquid surface and absorbed by this surface. v g andv l are specific volume for the gas and liquid respectively. L is the latent heatin J/kg. Based on this differential expression, variations in temperature can be obtained from variations of pressure close to the saturation conditions. V. Results and Discussion 4
By completion of all the test runs in Fluent, from the result we are understood the three cases of rate of heat transfer characteristics in shell and tube heat exchanger. By wounding the copper coil, it increases the turbulence intensity. The turbulence intensity is measuring the mixing of hot and cold fluid. So, the rate of heat transfer rate is increased. A. Comparison of three different cases: The rate of heat transfer depends upon the turbulence intensity, different cases [Base, Modification 1(sharp groove), Modification 2(plain edge)] of rate of heat transfer was analyzed in CFD simulation software. Thedetails are mentioned in table 3. Figure-4 Static pressure for modification-1in Fluent analysis It is the flow of static pressure Fluent layout of shell and tube heat exchanger with wounding of sharp edged grooves. TABLE-3 TEMPERATURE(K) STATIC TEMPERATURE MODEL STEAM- INLET TEMPERAT URE (K) STEAM- OUTLET TEMPERA TURE (K) BASE MODEL MODIFICAT ION 1 (SHARP GROOVES) MODIFICAT ION2 ( PLAIN GROOVES) 373 321.09 373 317.67 373 319.41 Figure-5 Static temperature for modification-1 in fluent layout It represent the flow of static temperature range in the Fluent of shell and tube heat exchanger for modification-1. RESULT OF MODIFICATION-1 STATIC PRESSURE TURBULENT INTENSITY Figure-6 Turbulent intensity for modification-1 in fluent layout. 5
It shows the maximum turbulentintensity in fluent layout. VELOCITY CONTOURS [5] Hetal Kotwal, D.S Patel, CFD analysis of shell and tube heat exchanger- A Review, International journal of engineering science and innovative technology (IJESIT) Volume 2, Issue 2,March 2013. [6] Ahmed F.Khudheyer and Mahmoud Sh.Mahmoud, Numerical analysis of Fin-Tube plate heat exchanger by using cfd technique, ARPN Journal of engineering and applied sciences Vol.6, NO. 7, July 2011, ISSN:1819-6608. Figure-7 Velocity contours for modification-1 in fluent layout The velocity flow diagram is represented in ANSYS Fluent. In this case represent the maximum velocity contours. REFERENCES [1] M.Sneha priya, G.Jamuna rani, Periodic flow simulation and heat transfer analysis using computational fluid dynamics, International journal of engineering research and applications (IJERA)- ISSN: 2248-9622, vol.2, Issue 3, May-Jun 2012, pp.2133-2144. [2] Santhosh Kansal, Mohd. Shabahat Fateh, Design and performance evaluation of shell and tube heat exchanger using CFD simulation, International jornal of engineering research & technology (IJERT), ISSN:2278-0181, Vol.3, Issue 7, July-2014. [3] B.Jayachandriah, K.Rajasekhar, Thermal analysis of tubular heat exchangers using ANSYS, International journal of engineering research volume no. 3, Issue no: Special 1, pp: 21-25. [4] Ankit Uppal, Dr. Vinod kumar, Dr.chanpreet singh, CFD analysis of heat transfer enhancement in a heat exchanger using various baffle arrangements, IJRMET Vol. 4, Issue 2, May-Oct 2014 ISSN:2249-5762(online) ISSN: 2249-5770(print). [7] Arjun K.S, and Gopu K.B, Design of shell and tube heat exchanger using computational fluid dynamics tools, Research journal of engineering sciences- Vol.3(7), 8-16,July (2014), ISSN:2278-9472 Res. J. Engineering Sci. [8] Sanjay kumar Sharma And Vikas Sharma, Maximizing heat transfer through fins using CFD as a tool, Inernational journal of recent advances in mechanical engineering (IJMECH), Vol.2, NO.3, Aug 2013. [9] Hesham G.Ibrahim, Experimental and CFD analysis of turbulent flow heat transfer in tubular exchanger, International journal of engineering and applied sciences, Dec.2014, Vol.5., NO.07, ISSN:2305-8269. [10] Russi Kamboj, Prof.Sunil Dhingra, Prof. Gurjeet Singh, CFD Simulation of Heat transfer enhancement by plain and curved winglet type vertex generators with punched holes, International journal of engineering research and general science, Volume 2, Issue 4, June-July 2014, ISSN:2091-2730. [11] N.D.Shirgire, P.Vishwanath Kumar, Review on Comparative Study between Helical Coil and StraightTube Heat Exchanger, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e- ISSN:2278-1684,p-ISSN:2320-334X, Volume 8, Issue 2(July- Aug. 2013), PP 55-59. 6