NUMERICAL INVESTIGATION OF HEAT TRANSFERR AND FLUID FLOW IN PLATE HEAT EXCHANGER WITH DIFFERENT OF PLATE MATERIALS

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 5, May 2017, pp , Article ID: IJMET_08_05_068 Available online at aeme.com/ijmet/issues.asp?jtype=ijmet&vtyp pe=8&itype=5 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed NUMERICAL INVESTIGATION OF HEAT TRANSFERR AND FLUID FLOW IN PLATE HEAT EXCHANGER WITH DIFFERENT TYPES OF PLATE MATERIALS D.V.Sai Teja and Dr Y.V.Hanumantha Rao Department of Mechanical Engineering KL University,Vaddeswaram, AP, India. ABSTRACT Numerical investigation of heat transfer and fluid flow in a single pass counter flow chevron corrugated platesplate heat exchanger considering methanol as hot fluid and water as cold fluid with different types of plate materials has been presented in this paper using commercial CFD software, ANSYS Fluent. The results of numerical simulation were compared with experimental data in order to verify the accuracy of the model. CFD simulations and Numerical analysis shows that using of Copper as plate material increases the heat transfer rate comparing to Aluminium and Inconelturbulence and 718 and it also shows that corrugation pattern of the plate develops vortices of fluid which results in high heat transfer rates. Key Words: Plate Heat Exchanger, Corrugated pattern, CFD Analysis. Cite this Article: D.V.Sai Teja and Dr Y.V.Hanumantha Rao Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials. International Journal of Mechanical Engineering and Technology, 8(5), 2017, pp IType=5 1. INTRODUCTION The plate heat exchanger consists of a pack of corrugated metal plates with portholes for the passage of the two fluids between which heat transfer will take place as given by Arun KumarTiwari [1] and also the plate pack is assembled between a fix frame plate and a movable pressure plate and compressed by tightening bolts. The number of plates is determined by the flow rate, physical properties of the fluids, pressure drop and temperature program. The plate corrugations promote fluid turbulence and support the plates against differential pressure. It is designed in such a way that cold fluid and hot fluid flows on the surface of the alternate plates that is cold fluid flows of in the first column between the two plates, hot fluid in the second column, cold fluid in third column e.tc., so that cold fluid flows on one side of the plate and hot fluid on the other side of the same plate as the plate is very thin having corrugations heat transfer takes place between the two fluids. Here the model is editor@iaeme.com

2 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials made in CATIA and CFD Simulation is used to investigate the heat transfer and fluid flow in PHE with only one plate. Computational Fluid Dynamics (CFD) is the science of predicting fluid flow, heat and mass transfer, chemical reactions, and related phenomena by solving numerically the set of governing mathematical equations which is stated in the ANSYS training module in second slide [2] 2. LITERATURE REVIEW A laboratory experimental facility was constructed and the thermal-hydraulic characteristics of three middle-size industrial PHE s were measured. The exchangers all had 24 plates of the same size but with different chevron angle combinations of 28 /28, 28 /60, and 60 /60. Two sets of tests were carried out with the three units: single-phase performance tests with water, and evaporator performance tests with R134a and R507A, for which the exchangers operated as refrigerant liquid over-feed evaporators. The tests with water served to provide accurate water-side heat transfer information for the evaporator performance analysis which is the primary purpose of this study. In the evaporator performance tests, refrigerant flow boiling heat transfer and two-phase pressure drop data were obtained under steady conditions, over a range of heat flux from 1.9 to 6.9 kw/m 2, refrigerant mass flux from 5.6 to 31.4 (kg/m 2 s), outlet vapour quality from 0.2 to 0/95, and saturation temperatures from 5.9 to 13.0 C which are taken from Performance analysis of plate heat exchangers used as Refrigerant evaporators: by jianchang huang[3] Additional field data of thermal performance were collected on an ammonia and a R12 PHE water chiller, operating as thermo-siphon evaporators at their design working conditions. Heat Transfer Analysis of Corrugated Plate Heat Exchanger of Different Plate Geometry: A Review By: Jogi Nikhil G, Assist. Prof. Lawankar Shailendra[4] Corrugated plate heat exchangers have larger heat transfer surface area and increased turbulence level due to the corrugations. In this study, experimental heat transfer data will obtained for single phase flow (water-to-water) configurations in a corrugated plate heat exchanger for symmetric 45 /45, 45 /75 chevron angle plates. The effect of variation of chevron angles with other geometric parameter on the heat transfer coefficient will be study. Reynold number ranging from 500 to 2500 and Prandtl number ranging from 3.5 to 6.5 will be taken for given experiment. Based on the experimental data, a correlation will estimate for Nusselt number as a function of Reynolds number, Prandtl number and chevron angle as said in Design and Cost Optimization of Plate Heat Exchanger By Sreejith K, Basil Varghese, Deepak Das, Delvin Devassy, Hari Krishnan K, Sharath G.[5] When the application is within the pressure and temperature limits of both designs, the selection process should focus on initial cost, maintenance requirements, and future operating conditions. The advantages of using PHE were investigated experimentally. The main conclusions are listed as follows by sreejith k[5]: A plate costs approximately Rs So the newly designed plate heat exchanger will cost approximately Rs which can replace the present two heat exchangers which together cost Rs This leads to great reduction in space and cost without affecting the heat will transfer efficiency. Initial cost is generally a function of approach temperature. Close approach temperatures temperature crosses favour the plate and frame heat exchanger while wide temperature approaches favour the shell and tube design editor@iaeme.com

3 D.V.Sai Teja and Dr Y.V.Hanumantha Rao When considering the maintenance costs, the determining factor should be the properties of fluid involve. When the fluid has a gr-eater tendency to foul, the plate and frame design offer easier access to heat transfer surface for cleaning. In addition, because of high turbulence, plate type heat exchangers have less of a tendency to scale or foul when compared to a shell and tube design. If your application requires a high probability against leakage, the better choice is shell and tube design. While the gasket is a weakness in the plate and frame design, the ability to expand or reduce the thermal capacity by adding or reducing plate s is a major advantage for the plate and frame heat exchanger. If you think the application may be expanded in the future, a plate heat exchanger is far the easiest and the most economical design. In the present numerical study, the heat transfer performance and fluid flow characteristics of various Nano fluids flowing in a counter flow PHE have been presented. The corrugated chevron PHE has been simulated, and the 3-D temperature and velocity fields have been obtained through numerical simulation. CFD based analysis has been used by considering Nano fluids as homogeneous mixture. Numerical investigation of heat transfer and fluid flow in plate heat Exchanger using Nano fluids By Arun Kumar Tiwari, Pradyumna Ghosh, Jahar Sarkar, Harshit Dahiya, Jigar Parekh[1] Compact heat exchangers are most widely used for heat transfer applications in industries. Plate heat exchanger is one such compact heat exchanger, provides more area for heat transfer between two fluids in comparison with shell and tube heat exchanger. The present work deals with experimental heat transfer data performed on plate type heat exchanger which is used in hydraulic cooling system in an industry. The heat exchanger used for carrying out this work consists of thin metal welded plates of stainless steel with 0.5mm thickness; distance between two plates is 5mm, chevron angle 60 and Counter flow arrangement. The total heat transfer area is m2. This consists of total 249 numbers of plates and it is designed to withstand with 65 C temperature with a flow rate of kg/h and cold fluid enters with a flow rate of kg/h at 35 C and leaves at C, pressure drop is neglected. The inlet and outlet temperatures of cold and hot fluids are been observed and with that conditions performance evaluation is done. Based on the experimental data, a correlation will estimate for Nusselt number as a function of Reynolds number, Prandtl number and chevron angle and the outputs obtained are convective heat transfer coefficient, overall heat transfer coefficient, and exchanger effectiveness. From the obtained results, graphs are drawn to assess the performance of the Gasketed Plate heat exchanger. Heat Transfer Analysis of Gasketed Plate Heat Exchanger: By: G.Anusha, P.S.Kishore[6] 1. Geometry: Figure 1 CATIA model of plate heat exchanger with one plate Figure 2 After patterning to three plates in Design modeller editor@iaeme.com

4 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Figure 3 After extracting fluid domain Above Figure 1 for simulation. Figure 2 model after patterning to three pates and figure 3 shows the model after extracting fluid domain and deleting the outer plates. Hence our model contains one plate and two fluid domains hot fluid and cold fluid on either side of the plate with geometry given in table: 1 Table 1 Geometry 2. Meshing: Length Width Thickness Diameter of Inlet/Outlet 192mm 74mm 0.75mm 18mm 1 Figure 4 Meshed body showing mid plate and fluid domain Figure 4 shows the mesh quality as we maintained to value of skewness below 0.8 and number of elements to 72, 47,019 Name selection have to be done to indicate the boundary editor@iaeme.com

5 D.V.Sai Teja and Dr Y.V.Hanumantha Rao conditions in fluent solver, here we have 8 named selections as two inlets and two outlets that is for hot fluid and cold fluid respectively and four interface surfaces hot and cold surfaces of the plate, hot and cold surfaces of fluid domains.[8] 3. NUMERICAL SIMULATION Finite volume discretisation approach were used from fluent commercial ANSYS software realisable k-ε model{eq. (1)& eq. (2)} were chosen after calculating the Reynolds s Number for used hydraulic diameter. We choose the materials according to their properties as we required given in the table 2. Boundary conditions used are given below in the table 3 [7],[8] ( ) + = (1) ( ) + = + + Where, + + (2) = (., ), =, = TABLE 2 Properties of materials and fluids Material Density kg/m^3 Specific Heat j/kg-k Thermal Conductivity w/m-k Aluminium Copper Inconel Methanol Water Table 3 Boundary conditions Boundary Type Hot Fluid mass flow inlet Cold Fluid mass flow inlet Hot fluid inlet temperature Cold fluid inlet temperature Hot/Cold fluid outlet pressure Magnitude 0.2 kg/s 0.2 kg/s 368 K 288 K 0 Pa editor@iaeme.com

6 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials 4. RESULTS AND DISCUSSION Temperature distribution Cu Al Inconel-718 plate Figure 5 Cold side temperature distribution on Cu, Al, and Inconel-718 plates Figure 6. Hot side temperature distribution on Cu, Al, and Inconel-718 plates editor@iaeme.com

7 D.V.Sai Teja and Dr Y.V.Hanumantha Rao The above figure 5 and figure 6 shows the Temperature distribution on the plates Cu, Al, and Inconel- 718 plates from cold side and hot side respectively. That there is no much bigger difference between the temperature distribution on copper and aluminum plates. As Copper and aluminum are good conductors of heat. Their temperature distributions on cold side of the plate and hot side of the plate are almost same. It is observed that very less heat is transferred from the hot fluid to cold fluid through Inconel plate when compared to Copper and Aluminum plates. Because, Inconel has very less thermal conductivity that is w/m-k whereas Copper and Aluminum has w/m-k and w/m-k respectively. The Figure 7 shows the variation of temperature on Copper, Aluminium and Inconel plates on a symmetric plane. It is observed that very less temerature variation on the Inconel plate compared to Copper and Aluminium plates. Figure 7 Temperature distribution on the surface of Cu, Al, Inconel plates on a symmetric plane The Figure 8 and figure 9 shows the Temperature distribution on a vortex generated surface[9] of Cu, Al, and Inconel-718 plate from cold fluid side and hot fluid side respectively As the vortex surface which we generated disturb the flow as result turbulence increases the turbulence in the flow increases the heat transfer rate from the hot fluid to cold fluid. Finally the cold fluid gains the more heat from the hot fluid because of this vortex surface. These vortex generated surfaces are mainly used to enhance heat transfer rate where the convective heat transfer coefficients are relatively lesser editor@iaeme.com

8 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Vortex Generated Surface Based Temperature Plot on Cold Side of the Plate Figure 8 Temperature distribution on Vortex generated surface of Cu, Al and Inconel-718 plates from cold fluid side Vortex Generated Surface Based Temperature Plot on Hot Side of the Plate: Figure 9 Temperature distribution on Vortex generated surface of Cu, Al and Inconel-718 plates from hot fluid side editor@iaeme.com

9 D.V.Sai Teja and Dr Y.V.Hanumantha Rao Table 4 Temperature values at outlet and inlets of different materials Boundary Copper Plate Aluminium Plate Inconel Plate Cold Fluid Inlet 288K 288K 288K Cold Fluid Outlet Hot Fluid Inlet 368K 368K 368K Hot Fluid Outlet The above table 4 shows the temperature at the outlet of cold fluids numerically we can understand that maximum heat transfer occurs in coper plate and temperature of outlet gained is high for it comparing to other materials (Al, Inconel-718)for copper plate among three because of its high thermal conductivity and low for the Inconel plate. Whereas Aluminum plate stands in between them. Based on the cold fluid outlet temperature we can understand that copper plate gives the more heat to cold fluid and increases its outlet temperature. Pressure distribution: Figure 10 Water side pressure distribution cu, al, Inconel plates Pressure distribution[10] contours shows the variation of pressure at different locations on the plate. The above Figure 10 shows the pressure distribution on cold side on Aluminum, Copper and Inconel plates respectively. It is observed that the maximum pressure at the inlet on the aluminum plate and copper plates is 0.94 bar where as on the Inconel plate it is 1 bar and it is dropped to very less values at the outlet on all the plates. The below figure11 shows pressure Distribution on hot side on Copper, Aluminum and Inconel-718 respectively editor@iaeme.com

10 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Figure 11 Pressure Distribution on Cu Al and Inconel plates on hot side VELOCITY DISTRIBUTION Figure 12 Stream lines of velocity on copper, aluminium, Inconel

11 D.V.Sai Teja and Dr Y.V.Hanumantha Rao Stream lines of velocity shows the magnitude of velocity at different locations on the plate Figure 12 shows the variation of velocity on aluminum, copper and Inconel plates respectively. It is observed that the maximum magnitude of velocity is almost equal on all the three plates as shown in the figures. The figures 13, 14 shows the variation of temperature along the length of the plate for hot and cold fluid respectively. We are noticed that copper is having high thermal conductivity of w/m-k. Because of this, the plate with copper material possess high heat transfer rate from hot fluid to cold fluid. Whereas, the plate with Inconel-718 having less thermal conductivity of 11.4 w/m-k material possess less heat transfer rate from hot fluid to cold fluid While the plate with the material Aluminum having the thermal conductivity of the order of w/m-k. As a result the plate with Aluminum as material possess the heat transfer in the range between the Copper plate and Inconel-718 plate. Cu_hot_side Al_Hot_Side Inc-718_Hot_Side Temperature, (K) Length along flow direction, (m) Figure 13 Temperature distribution along the length on plate of the hot fluid side editor@iaeme.com

12 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Cu_Cold_Side Al_Cold_Side Inc-718_Cold_Side Temperature, (K) Length along the flow, (m) Figure 14 Temperature distribution along the length on plate of the cold fluid side 5. NUMERICAL ANALYSIS The Table 5 and Table 6 shows the Non-Dimensional numbers like Reynold s number(r e ), Nusselt number(n u ) and Biot number(b i ) for hot fluid and Cold fluid respectively. [11].In this case we use the Corrugated plate which promote the turbulence in both the fluids. Later we calculate the Reynolds number (R e ), Nusselt number (N u ) and Biot number (B i ) from the following Empirical relations.the Prandtl number (pr) of both the Fluids are taken from Heat and Mass Transfer Data Book [12] R e =. = (3) (4) Where Graetz Number (GZ) is defined as GZ = Re.Pr. (5) editor@iaeme.com

13 D.V.Sai Teja and Dr Y.V.Hanumantha Rao S.NO Mass flow rate (Kg/sec) Table 5 Non- Dimensional numbers of Hot Fluid with varying Mass flow rate Velocity (M/sec.) Reynold s Number Nusselt Number Heat transfer coefficient (W/m 2 k) Biot number AL CU IN Table 6 Non-Dimensional numbers of Cold Fluid with varying Mass flow rate Mass S.NO flow rate (Kg/sec.) Velocity (M/sec.) Reynold s Number Nusselt Number Heat transfer coefficient (W/m 2 k) Biot number AL CU IN Finally we calculate the Biot number which relate the Thermal Conductivity of Metal that involved in Heat transfer B i = AS we know that Biot number is defined as the ratio of the internal conductive resistance offered by the Metal to the External Convective resistance offered by the fluid. Hence the Value of Biot number represents the resistance to Heat conduction indirectly as we keeping the same fluids properties throughout the process. The plate with Inconel-718 as material offers high Biot number and increases with mass flow rate. As Biot number is high then resistance to conduct heat through the plate is also high so the heat transfer rate through the Inconel-718 plate is very less as compared to other two metal plates.while the values of Biot number for the Copper Plate are very small, so the heat transfer rate through the Copper plate is very high and gives high performance in heat transfer than the two metal plates. The Aluminum plate offers the Biot number values in between the Copper and Inconel-718 Plates and it stands in between them in heat transfer rate also. The following Figures 15 and 16 shows the Variation of Biot number with Mass flow rate for Hot and Cold Fluids respectively. The Biot number variation with mass flow rate is very high for the Inconel-718 Plate as Compared to Aluminum and Copper Plates. (6) editor@iaeme.com

14 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Hence from the above numerical calculations we proved that the Copper as plate Material Enhances the Heat Transfer rate and it gives better Performance than the Al and Inconel-718 plates. We proved that Copper plate Possess the high heat transfer rate through CFD as well as through numerical Calculations than Al and Inconel-718 plates Biot number Mass flow rate (kg/sec.) aluminium copper inconel-718 Figure 15 Variation of Biot Number with Mass flow rate of Hot Fluid 30 mass flow rate of cold fluid Biot number aluminium copper inconel-718 Figure 16 Variation of Biot Number with mass flow Rate of Cold Fluid editor@iaeme.com

15 D.V.Sai Teja and Dr Y.V.Hanumantha Rao 6. EFFECTIVENESS CALCULATION Effectiveness of the Heat Exchanger is the ratio between actual Heat Transfer rate taking place between hot and cold fluids in the Heat Exchanger and the Maximum possible heat transfer rate between them. It indicates the performance of Heat Exchanger [13], [14] = Q actual = Actual Heat Transfer rate = Rate of Enthalpy change of either Fluids (7) = m h. Cph (T hi -T he ) = m. C pc (T ce -T ci ) (8) Q max = Maximum possible Heat Transfer Rate = (T hi T ci )(m. C p ) small (9) Where m. C p small is the smaller Heat Capacity rate between hot and cold fluids. Heat capacity rate of Methanol is smaller than Water in this case. Effectiveness of Heat Exchanger with Copper plate is given by(7) = ( ) ( ) = Effectiveness of Heat Exchanger with Aluminum plate is given by = ( ) ( ) = Effectiveness of Heat Exchanger with Inconel-718 plate is given by = ( ) ( ) = From all the above calculations we found that the Effectiveness of the Heat Exchanger with Copper as plate material is higher than the Al and Inconel-718.Hence the Performance of Copper Plate Heat Exchanger is better than that of Al and Inconel-718 Plate Heat Exchangers 7. CONCLUSION In this work Heat Exchanger concept was studied with Plate Heat Exchanger keeping unchanged hot and cold fluids for different types of Plate metal configuration, one model was made using CATIA and simulation done with help of ANSYS fluent with three different plate materials. Results were observed and verified with related papers. The corrugation pattern of the plate develops turbulence of fluid. Plate with Inconel-718 material performing poor because of its low thermal conductivity and high Biot Number and inversely plate with copper material performing well, obviously because of its high thermal conductivity and low Biot number. Aluminum stands in between copper and Inconel-718 in terms of Thermal Conductivity as well as in Biot number. The Effectiveness of Heat Exchanger with Copper Plate is more than that of Aluminum and Inconel-718 plates. As a result Copper Plate gives better performance than Al and Inconel-718 metal plates editor@iaeme.com

16 Numerical Investigation of Heat Transfer and Fluid Flow in Plate Heat Exchanger With Different Types of Plate Materials Hence, Among Copper, Aluminum and Inconel-718, Copper is better in all aspects.finally we can conclude from this work that using of plate material which has more thermal conductivity and less Biot number Possess more heat transfer. REFERENCES [1] Fluids arun kumar tiwari, pradyumna ghosh, jahar sakar, harshit dahiya, jigar paresh, numerical investigation of heat transfer and fluid flow in plate heat exchanger using nano,2014, volume85, November pages [2] Chapter 1- introduction to cfd introduction to cfx by ansys training lectures. [3] Jianchang huang,performance analysis of plate heat exchangers used as refrigerant evaporators [4] Jogi nikhil g, assist. prof. lawankar shailendra,heat transfer analysis of corrugated plate heat exchanger of different plate geometry: a review vol 5 issue 4 April 2016 [5] Sreejith k, basil varghese, deepak das, delvin devassy, hari krishman k, sharath g, Design and cost optimization of plate heat exchanger: volume(a) issue 10 (October 2014) pp [6] G.anusha, p.s kishore, Heat transfer analysis of gasketed plate heat exchanger volume number 5, issue no 12, pp [7] John d. anderson, computational fluid dynamics the basics with applications mcgraw-hill (India) 2012 [8] Jh ferziger and m peric, text book, computational methods for fluid dynamics 3rd edition. [9] Surajkumar.s,dr. ashok g. matani,heat transfer augmentation techniques in a plate-fin heat exchanger, vol 6, issue 3 January 2016 [10] Fantu a, tereda, n srihari, sarit k das and bebgt sunden, experimental study on port to channel flow distribution of heat exchanger. [11] Heat Transfer in Plate Heat Exchanger Channels :Experimental validation of Selected Co relations Equations By Janusz T Cieslinski, Artur Fiuk, Krzysztof Typinski,Bartlomiez Siemienczuk, Volume 37 (2016) No.3, 19-29* [12] Heat and Mass Transfer Data Book (Seventh Edition) New Age International Publications [13] SK som introduction to heat transfer, text book. [14] Heat and Mass Transfer: Fundamentals and Applications By Yunus A cengel, Afshin J.Ghajar. [15] Husam Mahdi Hadi, Qasim S. Mahdi and Nessrian Ali Hussien, Experimental and Numerical Investigation of Temperature Distribution For Meat During Freezing Process. International Journal of Mechanical Engineering and Technology, 7(3), 2016, pp editor@iaeme.com

17 D.V.Sai Teja and Dr Y.V.Hanumantha Rao Nomenclature PHE- Plate heat exchanger D -Diameter of inlet/outlet Cv - Control Volume R - Rutherford s Constant S -Modulus of the mean rate-of-strain tensor µ t - turbulent or eddy viscosity u, v & w - velocity components in the x, y and z directions. U i / x j & u j / x i Velocity gradients. S ij - Body forces - Production of kinetic energy G Turbulence due to buoyancy ε - Dissipation rate T Temperature p - Static pressure t Time, ρ density k - Thermal conductivity, W/m IN-718 Inconel-718 alloy C ph, C pc specific heat of hot and cold fluids respectively m h., mc. -mass flow rate of hot and cold fluids (kg/sec.) T ce, T ci temperature of cold fluid at exit and entry respectively T he, T hi temperature of hot fluid at exit and entry respectively - Effectiveness d e = Equivalent Diameter =2b in meters N= number of inter plate channels A c = channel flow cross section area in m 2 µ = Dynamic Viscosity in Pa-Sec h = Heat Transfer coefficient in W/m 2 k L = Length of the Plate in meters editor@iaeme.com