IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 01, 2015 ISSN (online):

Transcription

1 IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 01, 2015 ISSN (online): Analysis of Thermal Hydraulic Performance of Semicircular Pin Fin Heat Sink by using Computational Fluid Dynamics Swarup Bakre 1 Abhishek Arya 2 B.M Rathore 3 1 M. Tech. (Thermal Engineering) 2 Professor 3 Head of Department 1,2,3 Department of Mechanical Engineering 1,2,3 S.C.E/R.G.PV. Bhopal, India Abstract The study was conducted by using the Computational Fluid Dynamics (CFD) method. The heat sinks are used with high power semiconductor devices such as power transistors, electronic devices lasers and light emitting diodes (LED S). The major study was done on semicircular pin fin heat sink, a radii is taken as parameter. The heat transfer media was taken as an air & Aluminum (Al) as pin fin material. In our analysis, CFD was used and the model was developed on NX-5. In order to verify the present CFD model, the thermal resistance and the pressure drop are compared with the available experimental results present in the literature. And the design of semicircular Pin fin heat sink (SCPFHS) having radii is 0.5mm, 1.0mm and 1.0 mm. In this study, the simulations of SCPFHS at various wind velocity i.e., 6.5, 9.5, 12.5 & 15m/s and the configurations of pin-fins design are proposed. The results show that increasing wind velocity could reduce the thermal resistance and increase the pressure drop simultaneously. Key words: Plane pin fin heat sink, Electronics cooling simulation, Pressure Drop, Thermal Resistance I. INTRODUCTION The effective use of an electrical component is limited by its maximum operational junction temperature. To achieve a desired component temperature, excess heat dissipated by the device must be transferred to the environment [19]. The most common method for transferring heat from the component to the environment is to use a heat sink. To estimate a component s junction temperature, a required value is the heat sink s thermal resistance. The thermal resistance of heat sink can be determined analytically or experimentally. In electronic systems, a heat sink is a passive component that cools a device by dissipating heat into the surrounding air. In computers, heat sinks are used to cool electronic components. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronic devices such as lasers and light emitting diodes (LEDs), wherever the heat dissipation ability of the basic device package is insufficient to control its temperature. II. OBJECTIVE OF WORK The main objective of the current work is: 1) Validation of the CFD models by comparing the present simulated results with the Experimental result by Yue-Tzu Yang & Huan-Sen Peng [7]. 2) To predict velocity profiles and temperature for different wind velocity (6.5, 8, 10, 12.5 & 15 m/s) on the heat sink. 3) To simulate the heat sink of the semi circular pin fin having different radii and different velocity (6.5, 8, 10, 12.5 & 15m/s) for constant heat input. 4) Parameter sensitivity study of micro channel. 5) To define average heat transfer coefficient, thermal resistance and pressure drop for the heat sink of the different semi-circular pin fin profile and different velocity and constant heat input 10w. 6) To predict temperature distribution along the channel. III. PROBLEM FORMATION The study of various literatures we find the thermal resistance and pressure drop is higher as compared to present study. The purposes of this study reduce the thermal resistance, profit factor and increase the pressure drop at various wind velocity. Thus chosen semicircular pin fin in place of circular pin fin IV. RESULT AND ANALYSIS A three-dimension al model is developed to investigate flow and conjugate heat transfer in the heat sink for electronic applications. A series of numerical calculations have been conducted by FLUENT and the results are presented in order to show the effects of temperature distribution, overall heat transfer coefficient, Thermal Resistance, Surface Nusselt number in the heat sinks. A. Validation of the Experimental Result: The validation of the Experimental result is done by carrying out the simulation work on the Ansys Fluent 14.0 Work bench. B. Experimental and Simulation Result: The thermal resistance of the heat sink, R th, can be defined by- Where ΔT is temperature difference between the highest temperature on the fin base and the ambient air temperature, and Q is heat dissipation power applied on the fin base. Properties of the working fluid are the same as those of ambient air at 294 K, and the material of heat sinks is aluminum with thermal conductivity of 202 W/(m-K). The pressure drop (Δp) from the inlet to the outlet of the flow passage, which reflects the hydraulic performance of the heat sink, is calculated by Δp = p in - p out.(2) Both simulation results and Yue-Tzu Yang, Huan- Sen Peng experiment results [7] for thermal resistances and pressure drops of the PFHS are plotted in Fig.1 and 2 respectively. As can be seen in these figures C. Observation Table: 1) Pressure Drop: Wind Velocity (m/s) Experimental Result Simulation Results Err or % All rights reserved by 481

2 % % % % Table 1: Experimental and Simulation Result for the Plate Fin Heat Sink Fig. 4: Temperature distribution in Plane fin heat sink with 6.5m/s velocity Fig. 1: Experimental and Simulation results for the PFHS: Pressure Drop vs. Reynolds No. Fig. 2: Experimental and Simulation results for the PFHS: Thermal resistance vs. Reynolds No. Fig. 5: Temperature distribution in Plane fin heat sink with 8 m/s velocity Pin Model Type-1 Type-2 Type-3 Fig. 3: Experimental and Simulation results for the SCPFHS: Nusselt Number vs. wind velocities. Air Velocity(v) Fin base Temp. T (k) Temp. Diff. ( T) Pressure Drop ( P) Fig. 6: Temperature distributions in Plane fin heat sink with 10m/s velocity Thermal Pumping Nusselt Profit factor, resistance, R th power, E Number J (Q/E) (k/w) (w) (Nu) All rights reserved by 482

3 Type Table 2: Simulation of various Heat sinks Pin Model Fig. 7: Temperature distribution in 1mm Semicircular pin fin heat sink with 6.5m/s velocity Fig. 11: Velocity distribution in 1mm Semicircular pin fin heat sink with 8 m/s velocity Fig. 8: Temperature distribution in 1mm Semicircular pin fin heat sink with 8 m/s velocity Fig. 12: Velocity distribution in1mm Semicircular pin fin heat sink with 10m/s velocity Fig. 9: Temperature distribution in 1mm Semicircular pin fin heat sink with 10 m/s velocity Fig. 13: Temperature distribution in 2.0 Semicircular pin fin heat sink with 6.5m/s velocity Fig. 10: Velocity distribution in 1mm Semicircular pin fin heat sink with 6.5 m/s velocity Fig. 14: Temperature distribution in 2.0 Semicircular pin fin heat sink with 8m/s velocity All rights reserved by 483

4 Fig. 15: Temperature distribution in 2.0 Semicircular pin fin heat sink with 10m/s velocity Fig. 19: Temperature distribution in 2mm Semicircular pin fin heat sink with 6.5m/s velocity Fig. 16: Velocity distribution in2.0 Semicircular pin fin heat sink with 6.5m/s velocity Fig. 20: Temperature distribution in 2mm Semicircular pin fin heat sink with 8 m/s velocity Fig. 17: Velocity distributions in 2.0 Semicircular pin fin heat sink with 8 m/s velocity Fig. 21: Temperature distribution in 2mm Semicircular pin fin heat sink with 10m/s velocity Fig. 18: Velocity distribution in 2.0 Semicircular pin fin heat sink with 10m/s velocity Fig. 22: Velocity distribution in2mm Semicircular pin fin heat sink with 6.5m/s velocity All rights reserved by 484

5 Fig. 23: Velocity distribution in2mm Semicircular pin fin heat sink with 8m/s velocity Fig. 24: Velocity distribution in2mm Semicircular pin fin heat sink with 10m/s velocity Fig. 25: Experimental and Simulation results for the SCPFHS: Profit Factor vs. Reynolds No Fig. 26: Experimental and Simulation results for the SCPFHS: Nusselt No. vs. Reynolds No V. CONCLUSION 1) The CFD model was developed on NX-5 and analysis was done by Fluent ) The prediction of CFD model show good relation with experimental result present in literature [7]. 3) The internal consistency of the results confirms the validity of the CFD model. 4) Simulated the heat sink of Semicircular pin fin having different diameter (i.e. type1, type2, type3mm & type4) and different velocities (i.e. 6.5, 8,10,12.2 & 15m/s) for constant heat input. 5) From the above result we have least thermal resistance in semicircular pin fin with different diameter (Type-1) i.e. 1.4 K/W, after that (Type-2) i.e. 1.1 K/W,(Type-3) i.e. 1.6 subsequently with (Type-4) i.e. 1.5 K/W. 6) From the above result we have higher pressure drop in semicircular pin fin with (Type-1) i.e. 218Pa, after that (Type-2) i.e. 203, subsequently with (Type-3) i.e. 197Pa and (Type-4) i.e.202pa 7) So, from the above we can conclude that the Type-2 Semicircular pin fin at all velocity having better thermal resistance and pressure drop compared to Type-3 and Type-4 thermal resistance and pressure drop. REFERENCES [1] Manay E., Sahin B., Yilmaz M., Gelis K, Thermal Performance Analysis of Nanofluids in Microchannel Heat Sinks, World Academy of Science, Engineering and Technology [2] N. Nagarani, Experimental Heat Transfer Analysis on Annular Elliptical Fins and Comparison with Circular Fins, European Journal of Scientific Research, ISSN X Vol.73 No.2 (2012), pp [3] Hung-Yi Li a, Go-Long Tsai et al, Measurement of thermal and hydraulic performance of a plate-fin heat sink with a shield, Experimental Thermal and Fluid Science 42 (2012) [4] Ashish Kumar Pandey, A Computational Fluid Dynamics Study of Fluid Flow and Heat Transfer in a Micro channel, NIT, ROURKELA in [5] N.Nagarani et al, Experimental Heat transfer Analysis on Annular Circular and Elliptical fins, International Journal of Engineering Science and Technology Vol. 2(7), 2010, [6] Yue-Tzu Yang, Huan-Sen Peng, Numerical study of the heat sink with un-uniform fin width designs, International Journal of Heat and Mass Transfer 52 (2009) [7] Wuhan Yuan a, Jiyun Zhao, Numerical simulation of the thermal hydraulic performance of a plate pin fin heat sink, Applied Thermal Engineering 48 (2012) [8] Ch.Veerraju, M. Ram Gopal, Heat and mass transfer studies on plate fin-and-elliptical tube type metal hydride reactors, Applied Thermal Engineering, 30 (2010) [9] S. Lee, Optimum Design and Selection of Heat Sinks, Proceedings of 11th IEEE Semi-Thermal Symposium, pp , [10] H. Jonsson, B. Moshfegh, Modeling of the thermal and hydraulic performance of plate fin, strip fin, and pin fin heat sinks influence of flow by pass, IEEE All rights reserved by 485

6 Transactions on Components and Packaging Technologies 24 (2) (2001) [11] Aavid Engineering, Inc., EDS #117, Interface Materials, January 1992 [12] Patankar SV. Numerical Heat Transfer and Fluid Flow. New York: McGraw-Hill; CFD-Wiki Page [13] Sukhvinder Kang et al, The Thermal Resistance Of Pin Fin Heat Sinks In Transverse Flow, International Electronic Packaging Technical Conference and Exhibition, July 6 11, 2003, Maui, Hawaii, USA [14] Xiaoling Yu, Jianmei Feng, Development of a plate-pin fin heat sink and its performance comparisons with a plate fin heat sink, Applied Thermal Engineering 25 (2005) [15] Christopher L. Chapman et al, THERMAL Performance Of An Elliptical Pin Fin Heat Sink, S2-8/W/$ IEEE 24 Tenth IEEE SEMI-THERMP. [16] Kai-Shing Yang a, Wei-Hsin Chu, A comparative study of the airside performance of heat sinks having pin fin configurations, International Journal of Heat and Mass Transfer 50 (2007) [17] Holman, J. P., "Heat Transfer" McGraw-Hill, New York, (1986). [18] W. A. Khan, J. R. Culham, M. M. Yovanovich Modeling of Cylindrical Pin-Fin Heat Sinks for Electronic Packaging, /05/$ IEEE 21st IEEE SEMI-THERM Symposium. [19] Sergent, J. and Krum, A., Thermal Management Handbook for Electronic Assemblies, First Edition, McGraw-Hill, [20] G. Hetsroni, A. Mosyak, Heat transfer in microchannels: Comparison of experiments with theory and numerical results, International Journal of Heat and Mass Transfer 48 (2005) [21] R.C.Sachdeva, Fundamental of Engineering Heat and Mass Transfer New Age International Publishers (1988), ISBN: [22] Weilin Qu, Issam Mudawar, Analysis of threedimensional heat transfer in micro-channel heat sinks, International Journal of Heat and Mass Transfer 45 (2002) [23] W. Leonard, P. Teertstra, J.R. Culham, Characterization Of Heat Sink Flow Bypass In Plate Fin Heat Sinks, Asme International Mechanical Engineering Congress & Exposition November 17.22, 2002, New Orleans, Louisiana. [24] J. Richard Culham, Optimization of Plate Fin Heat Sinks Using Entropy Generation Minimization, IEEE Transaction on Components and Packing Technologies, Vol. 24, No. 2, June 2001 [25] Sparrow EM, Ramsey JW, Altemani CAC. Experiments on in-line pin fin arrays and performance comparisons with staggered arrays. J Heat Transfer, 1980; 102: [26] Anuradha, Sanyal and Pradip, Dutta and Srinivasan, K (2008) Numerical Study Of Heat Transfer From Pin Fin Heat Sink Using Steady And Pulsated Impinging Jets. In: 8th ASME/ISHMT Heat and Mass Transfer Conference, JNTU, Hyderabad. [27] Numerical Analysis of Convective Heat Transfer From an Elliptic Pin Fin Heat Sink With and Without Metal Foam Insert, Hamid Reza Seyf, Islamic Azad University, Karaj Branch, Tehran, Karaj, Iran, MD.Layeghi Assistant Professor, University of Tehran,, Tehran, Karaj, Iran. J. Heat Transfer -- July Volume 132, Issue 7 [28] B.Kundu, P.K.Das, Performance analysis and optimization of elliptic fins circumscribing a circular tube, International journal of Heat and Mass Transfer 50 (2007) [29] Chine-Nan lin, Jiin-yuh jang A two dimensional fin efficiency analysis of combined heat & mass transfer in elliptic fins. International journal of heat and mass transfer 45(2002.) [30] M. M. Rahman, Measurements of Heat Transfer in Microchannel Heat Sinks, International Communications in Heat and Mass Transfer, vol. 27, no. 4, pp , 2000 [31] N.V.S. Shankar, Rahul Desala, et al Flow Simulation to study the Effect of Flow Type on the performance of multi Material Plate Fin Heat Sinks ISSN: , IJESAT Mar-Apr 2012 [32] [33] Shakuntala ojha, CFD ANALYSIS ON FORCED CONVECTION COOLING OF ELECTRONIC CHIPS,NIT Rourkela,2009 [34] Yu XL, Feng QK, Liu QP. Research on the heat transfer and flow performance of a composite heat sink. J Xi an Jiaotong Univ 2003; 37(4):670 3 [in Chinese]. [35] N. Sahiti, A. Lemouedda, Performance comparison of pin fin in-duct flow arrays with various pin crosssections, Applied Thermal Engineering 26 (2006) All rights reserved by 486