International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 9, September 2018, pp. 58 62, Article ID: IJMET_09_09_007 Available online at http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=9 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 IAEME Publication Scopus Indexed EFFECTIVENESS OF HEAT TRANSFER INTENSIFIERS IN A FLUID CHANNEL GOWREESH S S Associate Professor, Department of Mechanical Engineering, JSSATE, Bangalore, India SRIKANTAMURTHY J S and VEERESH B R Assistant Professor, Department of Mechanical Engineering, JSSATE, Bangalore, India ABSTRACT Numerical investigations of fluid flow, heat transfer and pressure drop in an annular channel to enhance the heat transfer on different curved heating profiles are presented. In the present paper sequentially coupled approach is implemented to analyse the effectiveness of heat transfer intensifiers with different geometries of protrusions by using commercially available CFD software. A channel with heat intensifier models are designed and analysed for various geometries. With the implementation of intensifiers it is found that there is a significant amount of improvement in heat transfer efficiency. Pressure drop and Turbulent Kinetic Energy for the various heating channel surface model are studied. An experimental analysis is carried out to validate the numerically achieved results. The numerically calculated coefficients of heat transfer and pressure drops with respect to different geometrical protrusions found in the present study conforms to the observations of real life Heat transfer intensifiers of Fluid channel. Keywords: Intensifiers, Annular channels, CFD, Heat Transfer, Pressure drop. Cite this Article: Gowreesh S S,Srikantamurthy J S and Veeresh B R, Effectiveness of Heat Transfer Intensifiers in a Fluid Channel, International Journal of Mechanical Engineering and Technology, 9(9), 2018, pp. 58 62. http://www.iaeme.com/ijmet/issues.asp?jtype=ijmet&vtype=9&itype=9 1. INTRODUCTION Heat is one of the most important and expensive kinds of energy in many industrial applications, such as cooling towers, oil and gas flow in reservoirs and chemical processing, its high cost is determined by cost of its production (higher fuel prices, low efficiencies of heat generating installations) henceforth there is a great need to increase the heat transfer efficiency. Heat transfer intensifiers in a shell and tube heat exchangers makes it possible to reduce the mass of the heat exchange equipment and power consumption. http://www.iaeme.com/ijmet/index.asp 58 editor@iaeme.com
Effectiveness of Heat Transfer Intensifiers in a Fluid Channel A conclusion can be drawn from experiment and simulation works on tube with dimples which indicated that the dimples could disturb and mix the boundary layer and generate secondary flows that improve the turbulence level. Tube with semi-spherical protrusions does effective heat transfer the low pressure loss is required. An experimental analysis of study results reported in [1], the channel with intensifier having the ratio of height of the protrusion of the intensifier and the diameter of the channel less than 0.05 has a significant effect on the thermal and hydraulic efficiency. It is also concluded that numerical investigation is able to analyse the complete heat transfer in natural convection over an annular finned cylinder from where easy visualization about the heat transfer parameters are possible[2]. It is also concluded that the use of intensifiers with protrusions results in growth of flow friction in the annular channel [3-6] pressure losses are measured at different values of fluid flow rate. 2. METHODOLOGY Heat intensifiers with different geometrical protrusions shapes are modelled and analysed by using commercially available finite volume software. The governing differential equations [7] for continuity, momentum, energy and equation of state were integrated over a control volume and then discretized using the finite volume technique to obtain a set of algebraic equations. Sequentially coupled approach is implemented to analyse the fluid flow and heat transfer rate. Analysis is carried out for the inlet velocity of 0.1 m/s, flow patterns are plotted for all the models and heat transfer characteristics are studied. Experimental analysis is carried out for validating the numerical results. Analysis type Turbulence Model Fluid Casing Velocity Inlet Outlet conditions Table I Solver details and Boundary conditions Steady state, Heat Transfer K Turbulence Model with Wall enhanced treatment Water Aluminium 0.1 m/s Pressure outlet 3. EXPERIMENTAL METHOD Figure 1 and 2 shows the experimental setup. Experimental analysis is carried out for the plain tube for validation. Figure 1 Experimental Setup. http://www.iaeme.com/ijmet/index.asp 59 editor@iaeme.com
Gowreesh S S,Srikantamurthy J S and Veeresh B R Figure 2 Experimental Setup 4. NUMERICAL ANALYSIS CAD model is generated using commercially available software Figure 3 shows CAD models of three different geometries which are used for full flow analysis. Figure 3 CAD models Figure 4 Meshed models Figure 5 Boundary conditions Grid generation is carried out for the models using a commercially available meshing tool, Figure 4 shows the meshed model for all the geometries. Figure 5 shows the boundary conditions imposed, showing inlet and outlet locations where the fluid is entering and leaving the domain. XY plane is created for post-processing. http://www.iaeme.com/ijmet/index.asp 60 editor@iaeme.com
Effectiveness of Heat Transfer Intensifiers in a Fluid Channel 5. VALIDATION Figure 6 shows the comparison between experimental and numerically achieved results. It is found that numerical results are in good agreement with the experimental results. Figure 6 Experimental results Vs Numerical results (For inlet temperature of 55 and 65 o C) 6. RESULTS AND DISCUSSIONS During the flow of fluid inside the tube, parameters such as Temperature distribution/heat transfer rate, pressure drop and turbulent kinetic energy is studied. Figure 7,8,9 and 10 shows Temperature contours along global scale, local scale, pressure contours and turbulent kinetic energy for all the models respectively. Figure 7 Temperature contours Figure 8 Temperature contours (Local Scale) Figure 9 Pressure contours Figure 10 Turbulent Kinetic Energy http://www.iaeme.com/ijmet/index.asp 61 editor@iaeme.com
Gowreesh S S,Srikantamurthy J S and Veeresh B R Table II Results for different geometries Shape Inlet Velocity in m/s Temperature -OC Pressure drop Turbulence Inlet Outlet in Pa in J/kg Curved 0.1 77 76.40 6.68 4.70E-04 Square 0.1 77 76.17 6.63 3.33E-04 Triangular 0.1 77 76.34 9.02 5.29E-04 Table II shows Temperature, Pressure drop and Turbulence for all the models. From the results it is found that: Heat transfer rate for the square model found to be marginally higher than other two models. Pressure drop found to be almost same for Curved and Square models and highest for Triangular model. Turbulence in the domain found to be higher for the Triangular model and a minimum Turbulence for the Square model. 7. CONCLUSIONS It is possible to reduce consumption of structural materials for Heat Exchange Equipment production by a significant factor and decrease the energy consumption for pumping of heat transfer agents. Heat intensifiers with geometrical protrusions of shapes spherical, squares and triangular are studied. It is found that square model results in higher rate of heat transfer with lesser pressure drop and marginally lower turbulence in comparison with other two models. Further analysis can be carried out for optimized square model. REFERENCES [1] V.V.Olimpiev and B.G Morzoev, Effectiveness of channels with heat transfer intensifiers in the form of protrusions, Thermal Engineering, (2013) Vol. 60, No. 3, pp 182-189. [2] Jnana R. Senapati, Sukanta K. Dash, Subhranshu Roy, Numerical investigation of natural convection heat transfer over annular finned horizontal cylinder, International Journal of Heat and Mass Transfer 96 (2016) 330 345 [3] E.A Boltenko, A.N.Varava, A.V.Dedov, A.V.Zakharenkov, A.T.Komov and S.A Malakhovskii, Investigation of Heat Transfer and Pressure Drop in an Annular Channel with Heat Transfer Intensifiers, Thermal Engineering, (2015) Vol. 62, No. 3, pp 177-182. [4] V.V.Olimpiev and B.G Morzoev, Energy-Efficient Intensifiers of Laminar Heat Transfer,Russian Aeronautics, (2013) Vol. 56, No. 1, pp 185-190. [5] Yu.F.Gortyshov and I.A Popov, The Scientific Basis of Calculations of Highly Efficient Compact Heat-Transfer Apparatuses with Judicious Heat-Transfer Intensifiers, Thermal Engineering, (2006) Vol. 53, No. 4, pp 249-261. [6] I.A Popov, A.B. Yakovlev, A.V. Shchelchkov, D.V.Ryzhkov, and L.A. Obukhova, Prospective heat transfer enhancement methods for thermal power equipment, Energ. Tatarst.,(2011) No.1, 25-29. [7] [7] J.H. Ferziger, M. Peric, Computational Methods for Fluid Dynamics, third ed., Springer, 2002. http://www.iaeme.com/ijmet/index.asp 62 editor@iaeme.com