Computer Aided Design Analysis of Plate Type Heat Exchanger

Computer Aided Design Analysis of Plate Type Heat Exchanger

Mr. Dnyaneshwar B. Sapkal.

Student of Second year M.E. (CAD/CAM.) PRMIT&R Badnera, Amravati (M.S.).

Sant Gadge Baba Amravati University, Amravati (M.S.), India.

Dr. Samir. J. Deshmukh Associate Professor Mechanical Engineering Dept.

PRMIT&R Badnera , Amravati (M.S.). Sant Gadge Baba Amravati University, Amravati (M.S.), India.

Abstract -For many industrial applications plate heat exchangers are demonstrating a large superiority over the shell and tube and other types of heat exchangers. In this paper we design a copper plate heat exchanger for milk pasteurization in a food industry using high temperature in a short time. The efficiency of this device depends on numerous factor likes space requirement, material required for construction, pressure drop.Energy requirement for circulation of milk and water by pump.

In this paper we present a theoretical analysis of counter flow copper plate type heat exchanger and result and CFD analysis of pressure drop for milk and water over plate heat exchange .The result of CFD validate results predicted theoretically.

Knowing the hot and cold fluid stream inlet and outlet temperatures and mass flow rates of hot and cold fluid and respective heat capacities, and values of heat transfer coefficient. Mathematical model based on steady flow energy balancing for specific heat exchanger geometry and operational parameters the problem is numerically solved by LMTD method. This paper, present modeling done by PROE, CATIA V5R19, and the software analysis prediction of pressure drop and thermal analysis of plate heat exchanger done by CFD tools. CFD prediction are also validate with theoretical analysis of plate heat exchanger.

Key words – Plate heat exchanger, thermal performance, CFD, PROE, PHE, and LMTD.

1. INTRODUCTION

   A heat exchanger is specialized devices that assist the heat transfer of one fluid to other, in some cases a solid wall may separates the t fluid and prevent them from mixing. In other design the fluid may direct contact with each other. Plates or baffle fines are sometimes used with wall in order to increase surface area turbulence introduce. A common appliance containing heat exchanger includes air conditioner, refrigerator and space heater. A plate heat exchanger also used in food industry, processing industry, petroleum refineries, sewage treatments cargo ships, space heating chemical processing and power production, perhaps most commonly known heat exchanger is car

   radiator which cools the hot radiator fluid by taking advantage of air flow over a surface of radiator, there are three primarily flow arrangements with heat exchanger counter flow, parallel flow and cross flow. The counter flow heat exchanger is more effective and efficient design because the fluid flows in opposite sides.

   In order to select appropriate heat exchanger, Although the cost is often first consideration criteria evaluated and other several important selection criteria which includes pressure drop across heat exchanger , product mix , fluid flow, material required for construction

   ,thermal performance, high/low pressure limit, clean ability , maintenance and repair etc.

   The rates of heat flow at any points depends upon heat transfer coefficient, temperature difference between hot fluid and cold fluid, material, No. of plates, total heat transfer area of plates.

   The main objectives of this present paper theoretically analysis of copper plate heat exchanger, which more preferable over existing heat exchanger having stainless steel and economical analytically we compare volume required , material reduction, energy saving, and also pressure drops for milk and water . The result prediction pressure drop and temperature compare with CFD result.

2. DESIGN METHODOLOGY

The goal of heat exchanger design is to relate the inlet and outlet temperatures, the overall heat transfer coefficient, and the geometry of the heat exchanger, to the rate of heat transfer between the two fluids. The two most common heat exchanger design problems are those of rating and sizing. We will limit ourselves to the design of recuperates only. That is, the design of a two fluid heat exchanger used for the purposes of food pasteurization

.Two approaches to heat exchanger design that will be discussed are the LMTD method and NTU method. Each of these methods has particular advantages depending upon the nature of the problem specification. We discuss LMTD method for design PHE

Steps:

1 For constant specific heats with no change of phase, we may also write with a heat balance, the unknown process variable (flow rate or temperature) of one of the streams can be found.

Table: 1.Operating condition

And

Qc = (m Cp)c (Tc2 Tc1)

Qh = (m Cp)h (Tp Tp)

Now from energy conservation we know that Qc = Qh =Q.

1. Considering the type of fluids to be handled, a first guess of the overall the overall heat transfer coefficient Uo,

2. Then calculate LMTD to the some mean temperature difference by means of this relation:-

   T1 t2 T2 t1

   LMTD =

   T t

   Specification of Stainless steel plate heat exchanger

   ln 1 2

   T2 t1

3. With the assumed Uo, an value of the heat total heat transfer area of plate required can be calculated as At is given by relation.

   Q = UoAtTLM Ft

   Where,

   Uo = overall heat transfer coefficient in (W/

   (m²·c))

   Ft= log. Mean correction factor.

   TLM = log. Mean temp. difference.( ·c) hm = convective heat transfer coefficient.

   hw =convective heat transfer coefficient for water. tp = thickness of plate of plate ,

   K= Thermal conductivity of material.

4. Overall heat transfer coefficient (Uo), = + +

5. Choose the Effective Area of the plate, which includes plate length, width & thickness of plate.

6. Select the number pass arrangement. And Select the number of Plates required.

7. Total Material required in kg mass (m) = *V kg

8. Calculated Pressure Drop by milk and water can be calculated by using relation,

   P = 64/Re De * * V² /2De x*L

9. Power required for circulating milk & water P=Pressure drop (P) x mass flow rate (m )/Density( ) Watt.

   Equipment selection duty =2008KW Material = Stainless steel

   Pass arrangement = 1:1 Length L = 1.5m Width (w) = 0.5m Spacing = 3mm

   No. of channel (Nc) = 20 Thickness of plate (tp) =5mm No. of plate = 41

   Pressure drop for milk = P = 1879.95 N/ m2 Pressure drop for water = P = 1541.97 N/ m2

   Total power required circulation of Milk & Water by pump

   =104.26 Watt

   Energy required for circulation = 913 Units

   Specification of Copper plate Heat Exchanger:

   Equipment selection duty =2008KW Material = copper

   Pass arrangement = 1:1 Length (L) = 0.532m Width (w) = 0.5 m Spacing = 3mm

   Thickness of plate (tp) = 2.5mm No. of channel (Nc) = 20

   No. of plte = 41

   Pressure drop for milk = P = 666.88 N/ m2 Pressure drop for water = P = 545.91 N/ m2

   Total power required circulation of Milk& Water by pumps

   =36.90 Watt

   Energy required for circulation =323Units.

   Fig 1:3D Model of Plate heat exchanger with 41 plates.

   	Static Temperature = 4 [C]
   Boundary outlet Milk	Flow Regime = Subsonic
   Type OUTLET Pressure & Direction	Mass And Momentum – Opening Relative Pressure = 0 [Pa]
   Heat Transfer = Opening Temperature	Opening Temperature = 80 [C]
   Boundary Inlet Water	Flow Regime Subsonic
   Type INLET	Mass And Momentum – Normal Speed Normal Speed = 1.386 [m s^-1]
   Location inlet Water	Heat Transfer = Static Temperature
   Boundary Outlet Water Type OUTLET	Flow Regime – Subsonic Mass And Momentum – Opening
   Pressure & Direction Location Outlet Water	Relative Pressure = 0 [Pa Opening Temperature = 65 [C]

   Fig 2: Import geometry

   Fig3: Mesh model of Plate heat exchanger

   Table 2.: Mesh Report Mesh Information for CFX

   Domain	Nodes	Elements
   Milk	2371	8129
   Water	3816	12522
   All domain	6187	20651

   .

   Table 3:Boundary condition:

   Fig 4: Boundary condition

   Boundary Physics for CFX	Default Domain Setting:
   Boundary Inlet Milk	Flow Regime = Subsonic
   Type INLET	Mass And Momentum = Normal Speed Normal Speed = 0.74 [m s^- 1]
   Location inlet Milk	Heat Transfer = Static Temperature

   1. CFD RESULT AND DISCUSSION

      Fig 5: Pressure Drop variation for milk over plate.
      Zones	Value in Pa.	Discussion
      Blue	1.001e+002	Shows the very low pressure at the water outlet section due to extraction of heat with low flow velocity
      SkyBlue	2.278e+002	Shows	the	pressure	create	on
      		throughout milk plate.
      Red	7.026+002	Shows maximum pressure occurred at the inlet of water because due to high velocity value

      Fig. 7: Temperature distribution over plate.

      Pressure drop Analytical result:

      Value of pressure drop for milk =666.63 N/ m2 Value of pressure drop for water =545.91 N/ m2 Pressure drop CFD result:

      Value of pressure drop for milk = 598.1 N/ m2 Value of pressure drop for water = 533.3 N/ m2

      Temperature Analytical result Maximum temperature Value = 334 ·K Minimum temperature Value = 283 · K

      Temperature CFD results:

      Maximum temperature Value = 351·K Minimum temperature Value = 277 · K

      1. CONCLUSIONS

         1. It is concluded that the results obtained the total volume Occupied by the stainless steel material plate heat exchanger is 0.153m³, while the volume of the copper plate heat exchanger is 0.02727m³ using of copper material. Copper plate type heat exchanger results in an 82.17 % reduction in volume relative to the existing plate heat exchanger.

         2. Material required for the copper plate heat Exchanger is

            242.5 Kg but stainless steel plate heat exchanger is required 1232.45 Kg. Saving material required for construction copper material plate heat exchanger.

            Fig 6: Pressure Drop variation for water over plate
            Zones	Values in Pa.	Discussion
            Blue	9.728e+001	Shows very low pressure is created at the outlet section due to Extraction of heat with low velocity flow
            Sky-blue	1.942e+002	Shows the pressure create on thoughts the water plates
            Green	3.395e+002	Its shows the little high pressure occurred at the water flow side
            Yellow	4.364e+002	Shows the little high pressure occurred at middle section of water plates
            Red	5.817e+002	Shows the maximum pressure occurred at the inlet of water because due to high velocity value

         3. The pressure drop associated with the use of copper plate heat exchanger are significantly less than for conventional concentric tube configuration & the stainless plate heat exchanger. i.e. low power consumption.

         4. For circulating milk and water for stainless steel plate exchanger, the total power required 104.268Watt, the annual units required for circulating is 913.18 units. A copper material of plate heat exchanger required the total power 36.90Watt, the annual units required only 324.29 units.

         5. The CFD result of pressure drop is low as compare to the analytical result, & temperature results validate with analytical result we save energy require for circulation of water & milk is very low as compare to the stainless steel due to the above points hence prefer copper model of PHE.

         This is an attempt to validate the CFD predictions with that of the analytically result.

      2. REFERENCES

1. D. A. Anderson, John C. Tonnehill, Richard H. Pletcher A textbook of computational fluid Mechanics and Heat Transfer.

2. Numerical Analysis of Plate Heat Exchanger Performance in Co-Current Fluid Flow By H. Dardour,

   S. Mazouz, and A. Bellagi World Academy of Science, Engineering and Technology Vol:27 2009-03-29 Configuration

3. Dr.R.K. Bansal A text book of Fluid Mechanics and Hydraulic Machines, First Edition, Laxmi Publication (P) Ltd, pp. 1-6,160-167,256-282,576-577

4. A text book of Heat and Mass Transfer by R.K.Rajput Topic Heat Exchanger pp.805-840,

5. Facultatea de Energetica, Indrumar de schimbatoare de caldura,Bucuresti,28.03.2010,mhttp://insttermind.3x.ro

   /Index_files/Iti_indrumar.pdfSaber,M.H.&MazaherAtta in,H.(2010) Simulation and CFD Analysis of heat pipe exchanger.

6. Ahmet baylar, M. cihan aydin, Mehmet unsal and Fahri ozkan, Numerical modeling of heat exchanger for determining heat flow rates using fluent v 6.2. Vol. No. 2, pp. 97-108, 2009.

7. C.B.Prajapati, V.K.Patel, S.N.Singh, V.Seshadri. CFD analysis of permanent pressure loss for different types of flow meters in industrial applications, 37th National and 4th International conference of fluid mechanics & fluid power, dec-16-18, 2010 At IIT Madras.pp. 1-8

8. B. Apacoglu S. Aradag, CFD analysis of uncontrolled and controlled turbulent flow over a circular cylinder. 16-18 May 2011, Elazg, Turkey

9. Tutorial on FLUENT 12.0. Users Guide, FLUENT Inc., Lebanon,NH, 2012.

10. Lenfestey, A. G. Low Temperature Heat Exchangers, in Progress in K. Mendelsson (Ed) Cryogenics 3, 25- 47, (1961)H. Dardour, S. Mazouz, and A. Bellagi

11. Numerical Analysis Theory and Application372 Grigore,R; Popa ,S; Hazi,A &Hazi, G.(2010). Stud Regarding the Influence of the Plate Heat.

12. Exchanger Configuration on Its Performance, WSEAS Transactions on heat and MassTransfer, Issue 3, vol.5, pp.133-142, ISSN: 1790-5079

13. Gut,J.A.W.& Pinto, J. M.(2003). Modeling of plate heat exchangers with generalized configurations, International Journal of Heat and Mass Transfer, , pp. 2571-2585,ISSN:0017-9310.