(Luận văn thạc sĩ) nghiên cứu thiết kế kênh dẫn micro cánh xoắn đẳng giác bằng phương pháp taguchi

BỘ GIÁO DỤC VÀ ĐÀO TẠO TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT THÀNH PHỐ HỒ CHÍ MINH LUẬN VĂN THẠC SĨ PHẠM NGUYỄN PHI LONG NGHIÊN CỨU THIẾT KẾ KÊNH DẪN MICRO CÁNH XOẮN ĐẲNG GIÁC BẰNG PHƯƠNG PHÁP TAGUCHI NGÀNH: KỸ THUẬT NHIỆT - 1781009 SKC007095 Tp Hồ Chí Minh, tháng 11/2020 BỘ GIÁO DỤC VÀ ĐÀO TẠO TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT THÀNH PHỐ HỒ CHÍ MINH LUẬN VĂN THẠC SĨ PHẠM NGUYỄN PHI LONG NGHIÊN CỨU THIẾT KẾ KÊNH DẪN MICRO CÁNH XOẮN ĐẲNG GIÁC BẰNG PHƯƠNG PHÁP TAGUCHI NGÀNH: KỸ THUẬT NHIỆT - 1781009 Tp Hồ Chí Minh, tháng 11/2020 BỘ GIÁO DỤC VÀ ĐÀO TẠO TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT THÀNH PHỐ HỒ CHÍ MINH LUẬN VĂN THẠC SĨ PHẠM NGUYỄN PHI LONG NGHIÊN CỨU THIẾT KẾ KÊNH DẪN MICRO CÁNH XOẮN ĐẲNG GIÁC BẰNG PHƯƠNG PHÁP TAGUCHI NGÀNH: KỸ THUẬT NHIỆT - 1781009 Hướng dẫn khoa học: TS ĐẶNG HÙNG SƠN Tp Hồ Chí Minh, tháng 11 /2020 ii iii iv v vi vii viii ix liệu điều kiện người, v.v… điều đưa vào q trình mơ dẫn đến kết mơ kết tốt bỏ qua tổn thất 5.2 Kiến nghị: Đây hướng nghiên cứu dành cho thiết kế kỹ thuật nói chung tản nhiệt nói riêng nhằm tìm thiết bị vận hành tối ưu Ở nước ta phạm trù nghiên cứu mẻ gần chưa có báo nước cơng bố, nước ngồi tương đối áp dụng cho lĩnh vực truyền nhiệt Nên cần quan tâm đầu tư nghiên cứu hơn, bên cạnh việc gia cơng thiết bị với kích thước nhỏ cịn nhiều hạn chế, cần gia cơng với độ xác cao Hơn hết thời hạn nghiên cứu hạn chế nên chưa phong phú mặt liệu Kiến nghị nghiên cưu tiếp tục cải tiến nghiên cứu 67 TÀI LIỆU THAM KHẢO [1] D B Tuckerman and F R Pease, Microcapillary Thermal Interface Technology for VLSI Packaging, Digest of Technical Papers—Symposium on VLSI Technology, Maui, HI, pp 60– 61, 1983 [2] D B Tuckerman, Heat-Transfer Microstructures for Integrated Circuits, Ph.D thesis, Stanford University, 1984 [3] Cheng-Hsing Hsu, Jui-Chin Jiang, Hung-Son Dang, Thi-Anh-Tuyet Nguyen, Ching-Chuan Chang, Investigating the design parameters on spiralmicrochannel by using Fibonacci sequence and Taguchi method, Microsyst Technol 2017 (SCI), DOI: 10.1007/s00542-016-3262-z [4] Cheng-Hsing Hsu, Hung-Son Dang, Thi-Anh-Tuyet Nguyen, The application of Fibonacci sequence and Taguchi method for investigating the design parameters on spiral microchannel, IEEEE xplore 2016 (IE), DOI: 10.1109/ICASI.2016.7539784 [5] Cheng-Hsing Hsu, Jui-Chin Jiang, Hung-Son Dang, Thi-Anh-Tuyet Nguyen, Investigating the design parameters on the multi-layer micro-channel heat sink by using Quality Function Deployment and Taguchi method with the enlarged outlet, IEEE Explore 2017(IE), DOI: 10.1109/ICASI.2017.7988170 [6] Cheng-Hsing Hsu, Jui-Chin Jiang, Hung-Son Dang, Thi-Anh-Tuyet Nguyen, Investigating the Designed Parameters of Dual-Layer Micro-Channel Heat Sink by Design for Six Sigma (DFSS), IEEE Explore 2017 (IE), DOI: 10.1109/ICASI.2017.7988155 [7] Z.-X Li, D X Du, and Z.-Y Guo, Experimental Study on Flow Characteristics of Liquid in Circular Microtubes, Proc International Conference on Heat Transfer and Transport Phenomena in Microscale, pp 162–167, 2000 [8] Z.-Y Guo and Z.-X Li, Size Effect on Single-Phase Channel Flow and Heat Transfer at Microscale, International Journal of Heat and Fluid Flow, vol 24, pp 284–297, 2003 68 [9] P Gao, S Le Person, and M Favre-Marinet, Scale Effects on Hydrodynamics and Heat Transfer in Two-Dimensional Mini and Microchannels, International Journal of Thermal Sciences, vol 41, pp 1017–1027, 2002 [10] K.Park, K.J.Noh, K.S.Lee, Evaporative Modeling in a thin-film region of micro-channel, International Refrigeration and Air Conditioning Conference, 2002 [11] Matthew Law, Poh-Seng Lee, A comparative study of experimental flow boiling heat transfer and pressure characteristics in straight- and oblique-finned microchannels [12] Daxiang Deng, Ruxiang Chen, Hao He, Junyuan Feng, Yong Tang, Wei Zhou, Effects of heat flux, mass flux and channel size on flow boiling performance of reentrant porous microchannels [13] Henstroni G., Mosyak A., Pogrebnyak E., Segal Z., Explosive Boiling of Water in Parallel Microchannels, International Journal of Multiphase Flow 31, 2005 [14] Zhang L., Banerjee S S., Koo J-M., Laser D.J., Asheghi M., Goodson K E., Juan G Santiago J G., Kenny T W., Measurements and Modeling of TwoPhase Flow in Microchannels With Nearly Constant Heat Flux Boundary Conditions, Journal of Microelectromechanical Systems 11, 2002 [15] Kandlikar, S G., Fundamental issues related to flow boiling in minichannels and microchannels, Exp Therm Fluid Sci., 2002a [16] Kandlikar, S G., Two-phase flows patterns, pressure drop, and heat transfer during flow boiling in minichannel flow passages of compact heat evaporators, Heat Transfer Eng., 2002b [17] Kandlikar, S G., High flux heat removal with microchannels – a roadmap of opportunities and challenges, Proceedings of Third International Conference on Microchannels and Minichannels, 2005 [18] Kew, P A and Cornwell, K., On pressure drop fluctuations during boiling in narrow channels, Proceedings of Second European Thermal Sciences and 14 UIT National Heat Transfer Conference, 1996 69 th [19] Balasubramanian, P and Kandlikar, S G., An experimental study of flow patterns, pressure drop and flow instabilities in parallel rectangular minichannels, Heat Transfer Eng., 2005 [20] S M Marco, and L S Han, "A Note on Limiting Laminar Nusselt Number in Ducts with Constant Temperature Gradient by Analogy to Thin-Plate Theory," Trans ASME, (77): 625-630, 1955 [21] H E E Purday, Streamline Flow, Constable, London, 1949; same as An Introduction to the Mechanics of Viscous Flow, Dover, New York, 1949 [22] N M Natarajan, and S M Lakshmanan, "Laminar Flow in Rectangular Ducts: Prediction of Velocity Profiles and Friction Factor," Indian J Technol., (10): 435-438, 1972 [23] R K Shah, and A L London, "Laminar Flow Forced Convection in Ducts," Supplement to Advances in Heat Transfer, eds T E Irvine and J P Hartnett, Academic Press, New York, 1978 [24] W R Dean, "Note on the Motion of a Fluid in a Curved Pipe," Philos Mag., ser 7, (4): 208-223, 1927 [25] W R Dean, "The Streamline Motion of Fluid in a Curved Pipe," Philos Mag., ser 7, (5/30): 673-695, 1928 [26] Y Mori, and W Nakayama, "Study on Forced Convective Heat Transfer in Curved Pipes (lst Report, Laminar Region)," Int J Heat Mass Transfer, (8): 6782, 1965 [27] M Adler, "Flow in a Curved Tube," Z Angew Math Mech., (14): 257- 265, 1934 [28] S V Patankar, V S Pratap, and D B Spalding, "Prediction of Laminar Flow and Heat Transfer in Helically Coiled Pipes," J Fluid Mech., (62/3): 539-551, 1974 [29] P S Srinivasan, S S Nandapurkar, and S S Holland, "Friction Factors for Coils," Trans Inst Chem Eng., (48): T156-T161, 1970 70 [30] R L Manlapaz, and S W Churchill, "Fully Developed Laminar Flow in a Helically Coiled Tube of Finite Pitch," Chem Eng Commun., (7): 57-78, 1980 [31] R K Shah, and S D Joshi, "Convective Heat Transfer in Curved Ducts," Handbook of Single Phase Convective Heat Transfer, eds S Kakaq, R K Shah, and W Aung, Wiley Interscience, John Wiley & Sons, New York, 1987 [32] Y Mori, and W Nakayama, "Study on Forced Convective Heat Transfer in Curved Pipes (3rd Report, Theoretical Analysis under the Condition of Uniform Wall Temperature and Practical Formulae)," Int J Heat Mass Transfer, (10): 681695, 1967 [33] J M Tarbell, and M R Samuels, "Momentum and Heat Transfer in Helical Coils," Chem Eng., j m Lausanne (Netherlands), (5): 117-127, 1973 [34] N A Dravid, K A Smith, E W Merrill, and P L T Brian, "Effect of Secondary Fluid Motion on Laminar Flow Heat Transfer in Helically Coiled Tubes," AIChE J., (17): 1114-1122, 1971 [35] M Akiyama, and K C Cheng, "Laminar Forced Convection Heat Transfer in Curved Pipes with Uniform Wall Temperature," Int J Heat Mass Transfer, (15): 1426-1431, 1972 [36] C E Kalb, and J D Seader, "Fully Developed Viscous-Flow Heat Transfer in Curved Circular Tubes with Uniform Wall Temperature," AIChE J., (20): 340-346, 1974 [37] R L Manlapaz, and S W Churchill, "Fully Developed Laminar Convection from a Helical Coil," Chem Eng Commun., (9): 185-200, 1981 [38] V Kubair, and N R Kuldor, "Heat Transfer to Newtonian Fluids in Spiral Coils at Constant Tube Wall Temperature in Laminar Flow," Indian Journal Tech., (3): 144-146, 1965 [39] V Kubair, and N R Kuldor, "Heat Transfer to Newtonian Fluids in Coiled Pipes in Laminar Flow," Int J Heat Mass Transfer, (9): 63-75, 1966 71 [40] T.-H Shih, W.W Liou, A Shabbir, Z Yang, and J Zhu A New kϵ Eddy-Viscosity Model for High Reynolds Number Turbulent Flows – Modelevelopment and Validation Computers Fluids, 24(3):227-238, 1995 [41] B E Launder and D B Spalding The Numerical Computation of Turbulent Flows Computer Methods in Applied Mechanics and Engineering, 3:269289, 1974 [42] H C Chen and V C Patel Near-Wall Turbulence Models for Complex Flows Including Separation AIAA Journal, 26(6):641-648, 1988 [43] F White and G Christoph A Simple New Analysis of Compressible Turbulent Skin Friction Under Arbitrary Conditions Technical Report AFFDL-TR70-133, February 1971 [44] P Huang, P Bradshaw, and T Coakley Skin Friction and Velocity Profile Family for Compressible Turbulent Boundary Layers AIAA Journal, 31(9):1600-1604, September 1993 [45] Mehdi Ghobadi, Experimental Measurement and Modelling of Heat Transfer in Spiral and Curved Channels, May 2014 [46] K C Cheng, R C Lin, J W Ou, Fully developed laminar flow in curved rectangular channels, J of Fluids Eng 98 (1976) 41-48 [47] J D Seader, C E Kalb, Fully Developed Viscous-Flow Heat Transfer in Curved 109 Circular Tubes with Uniform Wall Temperature, AIChE Journal, vol 20, No 2, pp 340-346, 1974 [48] S W Chang, K F Chiang, J K Kao, Heat transfer and pressure drop in a square spiral channel roughened by in-line skew ribs", Int J of Heat and Mass Transfer 54 (2004) 3167-3178 [49] Winterton, R H S., Int J Heat Mass Transfer, 41, 809, 1998 [50] Petukhov, B S., in T F Irvine and J P Hartnett, Eds., Advances in Heat transfer, Vol 6, Academic Press, New York, 1970 72 INVESTIGATING THE UTILIZATION LOGARITHMIC EQUATION AND TAGUCHI METHOD FOR THE DESIGN PARAMETER SPIRAL MICRO-CHANNEL Hung-Son Dang, Nguyen-Phi-Long Pham, Thi-Anh-Tuyet Nguyen 1,2 Thermal Engineering Technology, Faculty of Vehicle and Energy Engineering/University of Technology and Education, 01, Vo Van Ngan, Thu Duc, Ho Chi Minh City, Vietnam Department of Industrial Systems Engineering, Faculty of Mechanical Engineering/University of Technology and Education, 01, Vo Van Ngan, Thu Duc, Ho Chi Minh City, Vietnam Email: sondh1986@gmail.com, phamlongspk@gmail.com, tuyetnguyen1986@yahoo.com Contact: +84 909 772 349, +84 858 428 288 +84 908 186 322 ABSTRACT In this day and age, seeking the most optimal micro-channel heat sink has never failed to catch the attention of the experts The opinion utilizes the natural shape properly is expected to create a design with the critical parameters define a new direction for design the engineering equipment The study applies the logarithmic equation into the microchannel model by combining the Taguchi method and the Computational Fluid Dynamic software (ANSYS Fluent 14) numerical function By a statistical approach, the Taguchi Method is using to optimize the parameters and improve the quality of geometry of the spiral microchannel heat sink Computational Fluid Dynamics (CFD) is the software using for solved numerically the set of governing mathematical equations for predict heat and mass transfer, fluid flow, and related phenomena The present examination to predict fluid flow and heat transfer Besides, the data were also analyzed by the Minitab 17 software The results delineate that the optimal design parameter can give good compromise was completed for the identification of the minimum thermal resistance of the microchannel heat sink Index terms: Micro-Channel heat sink, Spiral channel, Taguchi method, Logarithmic equation I INTRODUCTION Satisfy the expectation of customer and electronic industrial for a heat exchanger device, which has the most heat transfer performance A decrease in thermal resistance of heat sink was seen as the simple choice for this case There was a significant development of technology in electronic devices fabricated industry (e.g tablets and smartphones), that of devices was designed with smaller dimensions, higher power transfer dissipation, and faster procession, it known to namely Microchannel Heat Sinks (MCHS), it has never failed to catch special attention by engineers to meet customer demand For keeping the stable operation of electric devices is not discontinuous, the heat must be more consumed by heat 73 transfer devices The application of a variety of methods in the study has significantly solved of quality improvement for the MCHS however, that also is a cause for some problems of quality enhancement In 1981, Tuckerman and Pease [1] were the first paper that designed and tested microchannel heat sink for silicon integrated circuits Their research investigated performance forced liquid cooling in MCHS and the results showed that the maximum thermal o 2 resistance over cm area RT (0.09 C/Wcm ), and which has been tested up to 790 W/cm Various investigators have reported design methodologies, designs, prototypical concepts, comparative and experimental results, and bold innovations on the use of microchannel heat sinks Some investigators have suggested that designs should consider additional constraints such as noise limits, pressure distortion, vibration, and pumping losses but few have evaluated the effects of these constraints in a quantifiable fashion In 1998, Poh and Ng [2] conducted simulation and numerical analysis in microchannel heat sink by ANSYS Studying sixteen experiments, the heat exchanger models in the experiment was changed in the parameters: width, height, channel length, input velocity of coolant, and heat flux wall Poh and Ng showed that the effect of the microchannel length was slight, where a decline in length brings to an increase in the thermal resistance Similarly, thermal resistance grows with decreasing channel depth, increasing width, and declining input velocity Simulation and experimental results have similarities when compared to each other In the same time, Kawano et al [3] studies of pressure drop and heat transfer in microchannel heat sink by experimental and numerical studies In their experiments, 110 microchannels were arranged in a microchannel heat sink of a 15 × 15 mm2 area Water was used as the coolant The microchannel width was fixed at 57 µm, and the height used was either 180 or 370 µm A fully developed laminar flow was assumed in the numerical simulations The results of the experiments and simulations showed a similarity pressure drop with each other for < Re < 200 In this range, there was a significant change in the thermal resistance values at the input of the microchannel The viscosity of the water is dependent on temperature was considered the cause of this phenomenon, and there is a massive temperature gradient at the inlet For Re > 300, there was a difference in compared values, the pressure drop in the experiments was higher than those obtained in the simulations The thermal resistance change across the heat sink (from the entrance to exit) was approximately 0.1 K/Wcm , which shows that the temperature difference was 10K for a heat flux of 100 W/cm In 2000, Zeighami et al [4] studied the turbulent flows for water in microchannel heat sinks Previous work indicates at a Reynolds number lower than 2200 has the flow transition Cause of low transition Reynolds numbers could be surface roughness, viscous heating, and/or the electric double layer This transition number can only be studied experimentally Using micro resolution particle image velocimetry, vector fields were generated in a microchannel measuring 150 àm ì 100 àm ì cm at Reynolds numbers of 200, 720, 1200, and 1600 Except for the case where Re = 1600, all fields seemed steady and parallel When Re = 1600, the flow began to show some turbulent behavior The velocity fields temporally fluctuated and became more asymmetric In this time, Rahman [5] demonstrated the pressure drop and heat transfer in two different geometries of microchannel heat sinks by experimentally method The two configurations are I-channels and U-channels The parameters of the individual channels were the width of mm and the depths ranged from 176 to 278 µm The coolant is water, he 74 checked the pressure and temperature of the coolant along the microchannel The results represented that the Nusselt number in microchannels is higher than in larger channels, the cause is the surface roughness of the microchannel walls breaks down the velocity boundary layer In 2010, Sui et al [6] used numerical simulation to study the laminar liquid–water flow and heat transfer in three-dimensional wavy microchannels with a rectangular crosssection The results illustrate secondary flow (Dean vortices) can be generated when liquid coolant flows through the wavy microchannels The convective fluid is enhanced mixing, thus the heat transfer performance of the wavy microchannels is much higher, and the pressure drop of the wavy microchannels can be much smaller than that of straight microchannels with the same cross-section Furthermore, the relative wavy amplitude of the microchannels along the flow direction may be varied for various practical purposes, without compromising the compactness and efficiency of the wavy microchannels In 2010, Liu et al [7] studied of forced convection heat transfer occurring in microchannels by CFD (computational fluid dynamics) and LB (lattice Boltzmann) The results showed that the shield-shaped groove microchannel acquired high heat exchange performance with the growth of Nusselt number at about 1.3 times of the plain surface structure In 2012, Hung et al [8] used the finite volume method to analyze the heat transfer characteristics of a double-layered microchannel heat sink in their research By the geometric parameters optimization brought to the thermal resistance of the microchannel heat sink with the minimum value The results show that the thermal performance of the double-layered microchannel heat sink is better than that of the single-layered one in the same geometric dimensions, by an average of 6.3% In 2014, Hung et al [9] study the optimal geometric parameters design of a microchannel heat sink filled with a sintered porous medium The optimal number of channels are (N) = 108, channel-width ratio (β) = 0.90, and channel aspect ratio (α) = 8.15, with a minimum overall thermal resistance of 0.070 K/W over m area, and the overall thermal resistance is decreased by 40% over that of the initial guess (N = 56, β = 0.4, α = 4.8, and R T = 0.115 K/W over m area) After the review of the research mentioned above, it reveals two aspects to improve in MCHS First, the geometric dimensions are changed for micro-channel optimization, and the second is the analysis and design methods The changes orientated to improve MCHS quality, which has smaller dimensions and geometry Become to a micro-channel The relatively high and non-uniform temperature distribution along the channel is the most disadvantage of the MCHS This high and non-uniform temperature is a considerable effect in the electrical performance of IC chips or packages and then declines the via electricalthermal instability and thermal breakdown, etc, the cause is thermal stress generation Allow more coolant to flow through the channels is used to solve this problem, therefore the non-uniform temperature distribution is reduced, but there is an increase in the pressure drop Resolved that issue, we redesign the double layer channels for a specific geometry dimension But the higher expensive manufacturing and higher power supply requirement are many handicaps for the double-layer microchannel Seeking the most accordant channels has never failed to catch attention in research subjects The spiral microchannel has been studied in a variety of designs in the fields of biology, biochemistry, separation bacteria, blood, and bio-energy, but still fewer studies on the applications of curved channels and spiral channels have been conducted in the field of heat transfer 75 The reason of the present study is to use the Logarithmic equation in the design of microchannel heat sink parameters and to investigate thermal and fluid characteristics on the spiral microchannel heat sink in light of the recent advances in the micro-fabrication techniques, the optimal dimensions of the spiral microchannel heat sink are utilized to obtain the smallest thermal resistance as well as the effects on the working conditions of the channel AI LOGARITHMIC EQUATION AND LOGARITHMIC SPIRAL 2.1 Logarithmic equation A logarithmic spiral, equiangular spiral, or growth spiral is a self-similar spiral curve that often appears in nature Descartes makes the first description for the logarithmic spiral and then extensively investigated by Jacob Bernoulli, who called it Spiral mirabilis, "the marvelous spiral" There is a difference between the logarithmic spiral and the Archimedean spiral by the fact that the distances between the turnings of a logarithmic spiral increase in geometric progression, while in an Archimedean spiral these distances are constant In polar coordinates (r, θ) the logarithmic spiral can be written as: r = ae bθ = Or It can be represented in Cartesian coordinates: x (t ) = r (t ) cos(t ) = ae bt cos(t) y (t ) = r (t ) sin(t ) = ae bt sin( t) With e being the base of natural logarithms, and a and b being real constants In nature, one may easy to find curves that are logarithmic spirals Examples in Figure when we cut across a nautilus shell showing the section in that the chambers arranged in an approximately logarithmic spiral The plotted spiral (dashed blue curve) is based on the growth rate parameter (b = 0.759) Fig 1: The plotted spiral (dashed blue curve) (b = 0.759) 2.2 Logarithmic spiral By used equation no with a= 1, b=0.759, t value started from to 1.2π, we can create the Logarithmic spiral as shown in Figure 76 Fig 2: The spiral microchannel heat sink THE PROCEDURE OF DESIGN FOR LOGARITHMIC SPIRAL MICROCHANNEL HEAT SINK 3.1 The logarithmic spiral microchannel heat sink design In this study, the new model is designed to follow the Logarithmic equation, that model was named the Logarithmic spiral microchannel heat sink, as shown in Figure The model is the combination of the Logarithmic spiral microchannel heat sink's dimensions and geometry with a circular plane The boundary condition for all the channels in a given layer is supposed to be the same The bottom wall is heated with a completely uniform heat flux (qw) by a tangential plane with the chipset BI Fig 3: The Logarithmic spiral microchannel heat sink The response parameters of the Logarithmic spiral microchannel heat sink is thermal resistance assessed the effects to establish the initial parameters factors by the Taguchi method The levels and dimensions of each factor are selected and listed in Table The inlet velocity is created by the random distribution sequence (Matlab) For this reason, orthogonal arrays L27 is adequate for the research L27 is selected for investigation and three repetitions are run for response variable (i.e thermal resistance) The 3D model is built by the SolidWorks software The equation driven curve toolbox is used for making the Logarithmic 77 curve In this study, the optimal level of the parameters is the level with the smaller mean values is better In addition to the factor analysis, the correlation and the regression analysis relative to the model framework tests are performed to analyze data The ANSYS FLUENT 14.0 software package is used to simulate the heat transfer and the fluid flow phenomena and exported the simulation results That results is factor analyzed, correlation analyzed, and regression analyzed by Minitab 17 software Table 1: Parameters and their values levels Parameters Factors A: Chanel height (mm) B: Chanel width (mm) C: No of Channel D: Flow rate into H.E (l/m) E: Dimension of input piping (mm) F: Dimension of output piping (mm) 3.2 The conceptual framework of the study Based on the reviewed literature, the descriptive research model was investigated in this study and the conceptual framework of the study was proposed { }= 0+1 +2 +3 +4 +5 +6+ Hypothesis Model ( ): (the variables: ) is significant and positively related to thermal resistance ( ) Where { } are the values of the response variables in the ℎ trial for Model 0, 1, 2, 3, 4, 5, are parameters for Model The 2variables = ( namely, the value of the predictor variables in the ℎ trial for Model The random error terms are with the means of { } = and variances { } = , , , , , ) are known to be constants, , = 1,2,3, … ,27 IV RESULTS AND DISCUSSIONS 4.1 Correlation matrix analysis Based on the results from Minitab output, the correlations between predictor variables and response variables for each model have been obtained Table shows the correlation between predictor variables and response variables for Model, and factor , has the strongest negative correlation with a thermal resistance ( = −0.456, and − 0.417, respectively), which indicates an increase in factor will lead to a decrease in thermal resistance Table 2: The correlation analysis A B C D E Avedelta T 4.2 Regression analysis The F-Value and P-Value, which can be used to analyze the affection between predictor variables and response variables, and a value of 0.05 is chosen to indicate a significant 78 affection for each model Based on F-Value and P-Value of each predictor variable (factor), we can conclude For Model ( ): Factors have a significant effect on thermal resistance ( − = 0.012 0.007 ≤ 0.05, ) Factors B, D, E, and F have no significant effect on thermal resistance ( − = 0.135, 0.057, 0.465, 0.743 ≥ 0.05, ) In other words, we conclude , and reject , , , Table 3: Analysis of variance Analysis of Variance Source Regression A:Chanel B:Chanel C:No of D:Flowrate into E:Diamention of F:Diamention of Error Total height width (mm) chanel Besides, the average performance effects of each factor of the outlet velocity plot are also obtained for a visual inspection and the results contour result at the outlet cut view as given in Figure and Figure 5, respectively Fig.4: Mean effect plot of SN ratios for the Logarithmic spiral microchannel heat sink For this Model: The optimal combination factor of the thermal resistance is A3B3C3D1E1F1 (Channel height = 0.9 (mm)(A3), Channel width = 0.9 (mm)(B3), No of Channel = 10, the dimension of input piping = 9(mm), and the dimension of output piping = 4(mm) 79 Fig.5: The Contour plot for the Logathimic spiral microchannel heat sink V CONCLUSIONS The computational Fluid Dynamics software (CFD) (ANSYS 14) and Taguchi method were conducted to predict thermal resistance the Logarithmic spiral microchannel heat sink, and the results indicated the most valuable combination factors The optimal combination of thermal resistance is 3 1 1, and factors have the most significant effect on thermal resistance REFERENCES [1] D B Tuckerman and R F W Pease, (1981) “High-Performance Heat Sinking for VLSI,” IEEE Electron Device Letters, Vol 2, No 5, 1981, pp 126-129 [2] S T Poh and E Y K Ng, (1998) Heat Transfer and Flow Issues in Manifold Microchannel Heat Sinks: A CFD Approach, Proc Electronic Packaging Technology Conference, EPTC, pp 246– 250 [3] K Kawano, K Minakami, H Iwasaki, and M Ishizuka, (1998) Microchannel Heat Exchanger for Cooling Electrical Equipment, Proc ASME Heat Transfer Division, vol 3, pp 173–180 [4] R Zeighami, D Laser, P Zhou, M Asheghi, S Devasenathipathy, T Kenny, J Santiago, and K Goodson, (2000) Experimental Investigation of Flow Transition in Microchannels Using Micron Resolution Particle Image Velocimetry, Proc 7th Intersociety Conference on Thermomechanical Phenomena in Electronic Systems, ITHERM, vol 2, pp 148–153 [5] M M Rahman, (2000) Measurements of Heat Transfer in Microchannel Heat Sinks, International Communications in Heat and Mass Transfer, vol 27, no 4, pp 495–506 Y Sui, C.J Teo, P.S Lee, Y.T Chew, C Shu, (2010) Fluid flow and heat transfer in wavy microchannels, Int J Heat Mass Transfer 53 (13–14) 2760–2772 [6] [7] [8] [9] Y Liu, J Cui, Y.X Jiang, W.Z Li, (2011) A numerical study on heat transfer performance of microchannels with different surface microstructures, Appl Therm Eng 31 (5) 921–931 Hung TC, Yan WM, Li WP, (2012) Analysis of heat transfer characteristics of the double-layered micro-channel heat sink International Journal of Heat and Mass Transfer 55 3090–3099 Hung TC, Huang YX, Sheu TS, Yan WM, (2014) Numerical optimization of the thermal performance of a porous-micro-channel heat sink An International Journal of Computation and Methodology, 65:5, 419-434 80 ... - xii LỜI CAM ĐOAN Tôi cam đoan luận văn ? ?nghiên cứu thiết kế kênh dẫn micro cánh xoắn đẳng giác phương pháp Taguchi? ?? nghiên cứu Các số liệu, kết nêu luận văn trung thực chưa công bố cơng trình... PHỐ HỒ CHÍ MINH LUẬN VĂN THẠC SĨ PHẠM NGUYỄN PHI LONG NGHIÊN CỨU THIẾT KẾ KÊNH DẪN MICRO CÁNH XOẮN ĐẲNG GIÁC BẰNG PHƯƠNG PHÁP TAGUCHI NGÀNH: KỸ THUẬT NHIỆT - 1781009 Hướng dẫn khoa học: TS ĐẶNG... SƯ PHẠM KỸ THUẬT THÀNH PHỐ HỒ CHÍ MINH LUẬN VĂN THẠC SĨ PHẠM NGUYỄN PHI LONG NGHIÊN CỨU THIẾT KẾ KÊNH DẪN MICRO CÁNH XOẮN ĐẲNG GIÁC BẰNG PHƯƠNG PHÁP TAGUCHI NGÀNH: KỸ THUẬT NHIỆT - 1781009 Tp