Sixth sem progreflfojfpfpjss seminar.pptx

mechaincel thermal enginerring

1. Design and Development of Hybrid PCM-Synthetic jet based Heat Sink for Electronic Cooling Progress Seminar on Presented by : Rakesh Nandan A20ME09007 Under the Supervision of : Dr. Mihir Kumar Das Dr. Venugopal Arumuru School of Mechanical Sciences IIT Bhubaneswar, Odisha, India

2. Title : Design and Development of Hybrid PCM-Synthetic jet based Heat Sink for Electronic Cooling Submitted by : Rakesh Nandan Roll number : A20ME09007 Supervisor : Dr. Mihir Kumar Das Co-Supervisor : Dr. Venugopal Arumuru Date of joining : 24-August-2020 Date of Q exam : 20-September-2021 Date of Registration seminar : 27-June-2022 ACADEMIC INFORMATION RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 1

3. INTRODUCTION Heat sinks RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 2 Fin based PCM based Synthetic jet based Passive cooling Phase change cooling. Natural convection High latent heat Active cooling Forced convection High heat transfer coefficient No friction in parts Compact Low heat transfer coefficient Takes more surface area Low thermal conductivity Low thermal conductivity Figure 1. Working of the synthetic jet. PCM (Solid) PCM ( liquid ) Releases latent heat Absorbs latent heat

4. LITERATURE SURVEY Author Major findings Kandasamy et al. Increased power inputs enhance the melting rate as well as the thermal performance of the PCM-based heat sinks until the PCM is fully melted. Simulated problem is good agreement with experimental data. Results indicate the potential for PCM-based heat sinks for use in intermittent-use devices. Rasool Kalbasi The cooling ability of the novel heat sink (PCM in alternate slot) was better than the PCM-based as well as air-cooled heat sinks. As the convective coefficient increases, the positive effect strengthened and hybrid heat sink effectiveness become more apparent. Yang et al. PCM filled heat sink showed better thermal performance than the base case subjected to natural convection. In cyclic loading, with 30,000 W/m 2 heat flux having an on and off cycle of 160s subjected to heat transfer coefficient of 100 W/m 2 K -1 , the base case showed better performance. Al-Omari et al. Taguchi method was used to determine the optimal condition for fin angle, fin width, and fin pitch for better performance. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 3 PCM based heat sink

5. LITERATURE SURVEY Author Major findings Shaikh et al. The synthetic jet impingement gives better cooling than the forced cooling using fan. The steady state temperature attained for forced cooling is 49°C while it is 32°C for cooling using synthetic jet. Jalilvand et al. The air velocity obtained for synthetic jet and rotary fan are 7 and 2 m/s, respectively. Hence the synthetic jet can compete with the convectional rotary fans of smaller sizes. Lindstorm and Amitay Various orifice shapes were tested(rectangular, trapezoidal, triangular). The triangular geometry had better turbulence and generated more turbulence. Liu et al. Average flow velocity was maximum for 60 o orifice opening. Nusselt number was maximum for 60 o opening, around 30% more than the round orifice. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 4 Synthetic jet A review paper titled “ Hybrid cooling techniques for thermal management of the electronic devices: A review ” has been submitted.

6. OBJECTIVES To study the thermal performance of heat sinks with and without PCMs under constant load condition. (Completed) To study the thermal performance of heat sinks with and without PCMs under cyclic load condition. (Completed) To study the thermal performance of heat sinks with and without PCMs subjected to synthetic jet. (Ongoing) To develop a CFD model of PCM- synthetic jet-based hybrid heat sink for parametric study. (Ongoing) RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER :51

7. Work done so far Design and fabrication of experimental setup and heat sinks. Experiments for designed heat sink were conducted for constant power input (4 W, 6 W, 8 W, 10 W, and 12 W) with two different PCMs (Paraffin wax and 1-Hexadecanol). Design and fabrication of synthetic jet of three different geometries of orifices (Circular, Square, and Slot). Experiments for designed heat sink were conducted for cyclic power input (4 W, 6 W, 8 W, 10 W, and 12 W) with two different PCMs (Paraffin wax and 1-Hexadecanol). Experiments for three heat sink subjected to synthetic jet with circular orifice at 10 W, 15 W, 20 W, 25 W, and 30 W with two different PCMs (Paraffin wax and 1-Hexadecanol). Experiments for one heat sink heat sink subjected to synthetic jet with square orifice at 10 W, 15 W, 20 W, 25 W, and 30 W with two different PCMs (Paraffin wax and 1-Hexadecanol). RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 6

8. EXPERIMENTATION RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 6 Figure 2 . 3D model of the heat sinks and heat sink assembly.

9. EXPERIMENTAL RESULTS (CONSTANT LOAD) Why investigating cyclic load is important RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 10 Figure 3. Cyclic load supplied to the heat sinks. Cyclic load presents a practical scenario. The electronic components fail more frequently under cyclic load After the PCM is melted , the generated heat is not absorbed as latent heat . Then temperature of the heat sink base rises exponentially afterward. The advantage of PCM based heat sink is negated once the PCM is melted . So after the PCM is melted, it should be allowed to cool. The behavior of the PCM-based heat sink in cyclic loading must be studied . Selecting the cyclic load for the experimentation The heat time is the minimum time required for the 1-Hexadecanol to melt completely at 4W input power. The maximum cooling time considered is 50% of the heating time. The minimum cooling time considered is 15% of the heating time. And the third cooling time considered in 33%, which lies in the middle of the maximum and the minimum.

10. EXPERIMENTAL RESULTS (CYCLIC LOAD) Variation of base temperature with time for different heat sinks without PCM RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 10 Figure 4. Variation of heat sink base temperature of plate fin with time for varying heat input fill with, (a) no PCM, (b) 1-hexadecanol, and (c) Paraffin wax With increase in heat input the base temperature rises. After second cycle, the base temperature do change significantly even if the cooling time is reduced.

11. EXPERIMENTAL RESULTS (CYCLIC LOAD) RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER :112 Variation of base temperature with time for different heat sinks without PCM Figure 5 . Variation of heat sink base temperature of plate fin with time for varying heat input fill with, (a) no PCM, (b) 1-hexadecanol, and (c) Paraffin wax With increase in heat input the base temperature rises. At lower heat input (4W, 6W) base temperature rises after every cycle. Effect of PCM increases with increase in cooling time. But for heat input of 8W and above, the effect of PCM is not significant in second cycle onwards.

12. EXPERIMENTAL RESULTS (CYCLIC LOAD) RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 12 Variation of base temperature with time for different heat sinks without PCM Figure 6 . Variation of heat sink base temperature of plate fin with time for varying heat input fill with, (a) no PCM, (b) 1-hexadecanol, and (c) Paraffin wax With increase in heat input the base temperature rises. At heat input (4W) base temperature do not rise significantly after first. The effect of PCM is visible for heat input of 6W, 8W, and 10 W. The PCM melting point plays an important role in deciding the heat input.

13. EXPERIMENTAL RESULTS (CYCLIC LOAD) RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 13 Variation of base temperature with time for different heat sinks without PCM Figure 7 . Variation of heat sink base temperature of plate fin with time for varying heat input fill with, (a) no PCM, (b) 1-hexadecanol, and (c) Paraffin wax The PCM filled heat sink maintains a lower temperature compared to the unfilled heat sink. Out of the two PCM at 8W heat input, the 1-Hexadecanol performed better.

14. EXPERIMENTAL RESULTS (CYCLIC LOAD) RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 15 Variation of base temperature with time for different heat sinks without PCM Figure 8 . Variation of heat sink base temperature of plate fin with time for varying heat input fill with, (a) no PCM, (b) 1-hexadecanol, and (c) Paraffin wax The heat sink having square fin with cylindrical cavity attained relatively lower temperature compared to the other heat sink.

15. PUBLICATIONS Journal Paper: Nandan, R ., Arumuru , V., Rath, P. and Das, M.K., Experimental study of PCM based hybrid heat sink for electronic cooling. Journal of Enhanced Heat Transfer., vol. 29(3), pp. 1–15, 2022. DOI: 10.1615/JEnhHeatTransf.2022040469 (Published) Review Paper: Hybrid cooling techniques for thermal management of the electronic devices: A review. (Under review). Book Chapter : Nandan, R. , Arumuru , V., and Das, M.K., “Experimental Study of PCM Based Heat Sink for Thermal Management Electronic Chips”., Handbook of Thermal Management Systems., Elsevier. (Book chapter accepted) Conference: Nandan, R ., Arumuru , V., Rath, P. and Das, M.K., Effect of natural and forced convection on the PCM based hybrid heat sink for cooling of electronic components., International Symposium on Fluids and Thermal Engineering (FLUTE-2021)., Noida, India. Nandan, R ., Arumuru , V., Rath, P. and Das, M.K., Experimental study of PCM and synthetic jet based hybrid heat sink with cylindrical fins for electronic cooling., 9th International and 49th National Conference on Fluid Mechanics and Fluid Power (FMFP-2022)., Uttarakhand ., India. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 16

16. WORK PLAN Task name Sem 1 Sem 2 Sem 3 Sem 4 Sem 5 Sem 6 Sem 7 Sem 8 Course Work                 Literature Survey                 Objective 1                 Objective 2                 Objective 3                 Objective 4                 Thesis Writing                 RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER :16

17. References RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 17 [1] R. Kandasamy, X. Q. Wang, and A. S. Mujumdar, “Transient cooling of electronics using phase change material (PCM)-based heat sinks,” Appl. Therm. Eng. , vol. 28, no. 8–9, pp. 1047–1057, 2008, doi : 10.1016/j.applthermaleng.2007.06.010. [ 2 ] R. Kalbasi , “Introducing a novel heat sink comprising PCM and air - Adapted to electronic device thermal management,” Int. J. Heat Mass Transf. , vol. 169, p. 120914, 2021, doi : 10.1016/j.ijheatmasstransfer.2021.120914. [3] X. H. Yang, S. C. Tan, Z. Z. He, Y. X. Zhou, and J. Liu, “Evaluation and optimization of low melting point metal PCM heat sink against ultra-high thermal shock,” Appl. Therm. Eng., vol. 119, pp. 34–41, 2017, doi : 10.1016/j.applthermaleng.2017.03.050. [4] Al-Omari, S.A.B., Qureshi, Z.A., Elnajjar , E. and Mahmoud, F., 2022. A heat sink integrating fins within high thermal conductivity phase change material to cool high heat-flux heat sources. International Journal of Thermal Sciences, 172, p.107190. [5] Shaikh A, Kumar S, Dawari A, Kirwai S, Patil A, Singh R. Effect of temperature and cooling rates on the α+ β morphology of Ti-6Al-4V alloy. Procedia Structural Integrity. 2019 Jan 1;14:782-9. [6] Jalilvand , A., Mochizuki, M., Singh, R., Saito, Y., Kawahara, Y. and Wuttijumnong , V., 2014. Air Impingement Cooling by Synthetic Jet. Journal of Thermal Science and Engineering Applications, 6(3), p.031008. [ 7 ] A. Lindstrom and M. Amitay, “Effect of orifice geometry on synthetic jet evolution,” AIAA J., vol. 57, no. 7, pp. 2783–2794, 2019, doi : 10.2514/1.J058135. [8] Y. H. Liu, T. H. Chang, and C. C. Wang, “Heat transfer enhancement of an impinging synthetic air jet using diffusion-shaped orifice,” Appl. Therm. Eng., vol. 94, pp. 178–185, 2016, doi : 10.1016/j.applthermaleng.2015.10.054.

18. Thank You

19. EXPERIMENTATION Synthetic jet orifice plate with varying geometry RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 7 CIRCULAR ORIFICE PLATE SLOT ORIFICE PLATE SQUARE ORIFICE PLATE

20. EXPERIMENTAL RESULTS Optimization of the Synthetic jet diaphragm frequency RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 8 Figure 1. Variation of peak velocity at the exit of the orifice with change in frequency of the diaphragm. Optimum frequency: 800 Hz Amplitude: 40 V

21. EXPERIMENTAL RESULTS (CONSTANT LOAD) Height optimization of the synthetic jet from the heat sink RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 9 Figure 2 . Variation of temperature with increase in height of the synthetic jet for heat sink filled with and without PCM. Optimum height Suction phase Expulsion phase Hot air Too close to the heated surface Far away from the heated surface Hence optimization is crucial for best performance Velocity of jet reduces

22. METHODOLOGY Figure 6. Schematic of experimental setup Experimental study Silicone heater Silicone heater is connected to the DC power supply. Heat generated by heater is dissipated by the PCM based heat sink . Thermocouples inserted in the heat sink base to measure base temperature. Thermocouple is connected to Data Acquisition System , which is further connected to computer. Synthetic jet provided at the top of the heat sink. Oscillation of synthetic jet is controlled with amplifier . RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 12

23. Material Melting point (° C) Specific heat (J/kg. K) Density (kg/m 3 ) Latent heat (kJ/kg) Thermal conductivity (W/m. K) Paraffin 58-60 2540 920 189 0.21 EXPERIMENTATION PAPER ID: 3522 FMFP 2022 SLIDE NUMBER : 8 Figure 6. Heat sink with cylindrical cavity Figure 7. Synthetic jet with multiple orifice Figure 8. Heat sink assembly Table 2 . Thermophysical properties of Paraffin wax

24. LITERATURE GAP An extensive study on the geometric parameters of the PCM based heat sink has not been conducted . Nanoparticles remain a major challenge because they settle down after a finite time, a proper solution for this has not been reported. Integration of the condenser part of the heat pipe through liquid cooling has not been reported. Study on microchannel and PCM based heat sink has not been reported. Integration of Synthetic jet with PCM based heat sink has not been reported. Numerical model for Synthetic jet coupled with PCM based heat has not be reported. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 10

25. INTRODUCTION Figure 1. Increase in number of transistors with time. Management of heat dissipation is essential for electronic devices Source: Ren, Z., 2017.  Thermoelectric Cooling by Holey Silicon and the Role of Thermal Conductivity Anisotropy  (Doctoral dissertation, UC Irvine). Figure 2. Major Causes of electronic failures High performance requirement and small size High heat density Failure Source: Sahoo et al., 2016 RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 3

26. EXPERIMENTATION Experimental setup Figure 7. Image of experimental setup Heat sink assembly Data Acquisition System Data logger for heat flux sensor Amplifier connected to Synthetic jet Computer for recording thermocouple reading Computer for controlling synthetic jet input DC power supply RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 13

27. EXPERIMENTATION Plate fin Cylindrical fin with cylindrical cavity Square fin with cylindrical cavity Figure 8. Heat sink designs Heat sink designs The volume of PCM and base dimensions have been kept constant Material name : Aluminium alloy 6063 Thermal conductivity : 200 W/m.K Volume of PCM: 18900   RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 14

28. EXPERIMENTATION 3D model Heat flux sensor (50 x 50 mm) Data logger Actual image of Teflon base Silicone rubber heater (50 x 50 mm) DC power supply Thermal conductivity: 0.25 W/m.K Range: -10000 to 10000 W/   Voltage: 0 – 80 V Current: 0 - 30 A Maximum power: 50 W Figure 9. Equipment and accessories for experimentation RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 15 50 mm 50 mm

29. EXPERIMENTATION Synthetic jet fabrication 19 mm Synthetic jet cavity Synthetic jet orifice Synthetic jet diaphragm Synthetic jet assembly Inner dia : 46 mm Outer dia : 50 mm Width: 19 mm Material: Aluminum alloy 6063 Diameter: 50 mm Piezo material: PZT Diaphragm material: Brass Diameter: 50 mm Thickness: 2 mm Hole dia : 3 mm Material: Acrylic Single orifice Multiple orifice Single orifice Multiple orifice Figure 10. Fabrication of Synthetic jet RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 16

30. EXPERIMENTATION Heat sink assembly Figure 11. Exploded view of heat sink assembly Heat flux sensor is placed between the silicon rubber heater and heat sink . Teflon base stops the heat generated by heater from escaping . The top surface of the heat sink is open to ambient . Heat dissipated only through the top surface of the heat sink. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 17

31. OPERATING PARAMETERS AND MATERIAL PROPERTIES RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 18 Input parameters for PCM based heat sink in literature Author Year Type of work PCM used and melting point Heat flux (KW/m 2 ) Base dimension (mm x mm) Peak temperature Nayak et al 2006 Numerical Eicosane 37 °C 2.26 42 x 42 80 Kandasamy et al 2007 Experimental and numerical Paraffin wax 53 – 57 °C 2.22 – 4.44 30 x 30 50 – 75 °C Fok et al 2009 Experimental Eicosane 36 °C 0.3 – 1.1 90 x 70 45 °C Baby and Balaji 2012 Experimental Eicosane 36 °C 0.4 - 1.4 80 x 62 70 °C Baby and Balaji 2013 Experimental Paraffin wax 53 – 57 °C Eicosane 36.5 °C 1.5 – 3.9 60 x 42 70 °C Gharbi et al 2015 Experimental Paraffin wax 59 °C 3.1 51.5 x 25.5 60 °C Srikanth and Balaji 2017 Experimental Eicosane 36 °C 2.3 60 x 42   Ali and Arshad 2017 Experimental Eicosane 36.5 °C 0.8 – 2.8 100 x 100 70

32. OPERATING PARAMETERS AND MATERIAL PROPERTIES Operating parameters Input power (W): 4, 6, 8, 10, 12 Heat flux (KW/ ): 1.6, 2.4, 3.2, 4, 4.8 PCM used: Paraffin wax, 1-Hexadecanol, Eicosane Forced convection: DC fan, synthetic jet   RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 19

33. OPERATING PARAMETERS AND MATERIAL PROPERTIES Materials Melting point (° C) Specific heat (J/kg. K) Density (kg/m3) Latent heat (kJ/kg) Thermal conductivity (W/m. K) Paraffin 58-60 2540 920 189 0.21 1-heaxadecanol 48-50 2120 811 226.1 0.3 Thermophysical properties of PCM Component Material Specific heat (J/kg. K) Density (kg/m3 ) Thermal conductivity (W/m. K) Heat sink Alluminum 940 2712 189 Insulation base Teflon 1172 2200 0.25 Thermophysical properties of materials RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 20

34. INTRODUCTION RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 5 PCM (Phase change materials) PCM (Solid) PCM ( liquid ) Releases latent heat Absorbs latent heat Classification: Organic(Contains carbons/Hydrocarbons) Inorganic(not carbon based) Eutectic compound Type of PCM Thermal conductivity Latent heat Corrosiveness Cost Organic Low High No Low Inorganic High High Yes High Out of all the PCM available organic based are suitable for use in electronic devices Figure 3: Study on different PCMs in literature

35. INTRODUCTION Synthetic jet Basic components Diaphragm (vibrating membrane) Orifice and orifice plate Cavity Working of Synthetic jet The ingestion phase starts when the diaphragm moves away from the cavity, and this motion increases the volume of the SJ cavity. This decreases pressure inside the cavity, and the fluid is inducted into the cavity. The diaphragm moves towards the cavity in the expulsion phase , reducing the cavity volume. This increases the pressure inside the cavity, and the fluid is pushed out of the orifice. While the fluid is being pushed out, a boundary layer is formed along with the orifice, which retards the motion of the outgoing fluid leading to vortex formation. This vortex formation generates turbulent flow, which helps in the removal of heat. RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 6 Figure 4. Working of the synthetic jet.

36. INTRODUCTION RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 7 Comparison of S ynthetic jet (SJ) over Continuous jet (CJ) SJs are simple in design, easy to handle and requires less maintenance. SJs leads to formation of vortices which causes increased turbulence. Therefore the heat transfer is enhanced. Synthetic jet spreads more rapidly than CJ. Figure 5. Venn diagram on number of articles published for different heat sink types. Data collected from SCOPUS. Keywords: Fin based heat sink for electronic cooling, PCM based heat sink for electronic cooling, Synthetic jet based heat sink for electronic cooling. PCM-Synthetic jet based heat sink has not been reported till now

37. References RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 30 [8] W. Q. Li, Z. G. Qu, Y. L. He, and Y. B. Tao, “Experimental study of a passive thermal management system for high-powered lithium ion batteries using porous metal foam saturated with phase change materials,” J. Power Sources, vol. 255, pp. 9–15, 2014, doi : 10.1016/j.jpowsour.2014.01.006. [9] A. Arshad, H. M. Ali, S. Khushnood , and M. Jabbal , “Experimental investigation of PCM based round pin-fin heat sinks for thermal management of electronics: Effect of pin-fin diameter,” Int. J. Heat Mass Transf., vol. 117, pp. 861–872, 2018, doi : 10.1016/j.ijheatmasstransfer.2017.10.008. [10] M. J. Ashraf, H. M. Ali, H. Usman, and A. Arshad, “Experimental passive electronics cooling: Parametric investigation of pin-fin geometries and efficient phase change materials,” Int. J. Heat Mass Transf., vol. 115, pp. 251–263, 2017, doi : 10.1016/j.ijheatmasstransfer.2017.07.114. [11] X. Q. Wang, A. S. Mujumdar, and C. Yap, “Effect of orientation for phase change material (PCM)-based heat sinks for transient thermal management of electric components,” Int. Commun . Heat Mass Transf., vol. 34, no. 7, pp. 801–808, 2007, doi : 10.1016/j.icheatmasstransfer.2007.03.008. [12] R. Baby and C. Balaji, “Experimental investigations on thermal performance enhancement and effect of orientation on porous matrix filled PCM based heat sink,” Int. Commun . Heat Mass Transf., vol. 46, pp. 27–30, 2013, doi : 10.1016/j.icheatmasstransfer.2013.05.018. [13] X. H. Yang, S. C. Tan, Z. Z. He, Y. X. Zhou, and J. Liu, “Evaluation and optimization of low melting point metal PCM heat sink against ultra-high thermal shock,” Appl. Therm. Eng., vol. 119, pp. 34–41, 2017, doi : 10.1016/j.applthermaleng.2017.03.050. [14] L. W. Fan et al., “Transient performance of a PCM-based heat sink with high aspect-ratio carbon nanofillers,” Appl. Therm. Eng., vol. 75, pp. 532–540, 2015, doi : 10.1016/j.applthermaleng.2014.10.050.

38. References RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 31 [15] L. W. Fan et al., “Effects of melting temperature and the presence of internal fins on the performance of a phase change material (PCM)-based heat sink,” Int. J. Therm. Sci., vol. 70, pp. 114–126, 2013, doi : 10.1016/j.ijthermalsci.2013.03.015. [16] H. Wang, F. Wang, Z. Li, Y. Tang, B. Yu, and W. Yuan, “Experimental investigation on the thermal performance of a heat sink filled with porous metal fiber sintered felt/paraffin composite phase change material,” Appl. Energy, vol. 176, pp. 221–232, 2016, doi : 10.1016/j.apenergy.2016.05.050. [17] X. Hu and X. Gong, “Experimental study on the thermal response of PCM-based heat sink using structured porous material fabricated by 3D printing,” Case Stud. Therm. Eng., vol. 24, no. July 2020, p. 100844, 2021, doi : 10.1016/j.csite.2021.100844. [18] R. Akula , A. Gopinath, S. Rangarajan, and C. Balaji, “Experimental and numerical studies on heat transfer from a PCM based heat sink with baffles,” Int. J. Therm. Sci., vol. 159, no. August 2020, p. 106525, 2021, doi : 10.1016/j.ijthermalsci.2020.106525. [19] A. Lindstrom and M. Amitay, “Effect of orifice geometry on synthetic jet evolution,” AIAA J., vol. 57, no. 7, pp. 2783–2794, 2019, doi : 10.2514/1.J058135. [20] O. Isil, “$ Q , Qyhvwljdwlrq Ri 3Huirupdqfh Ri 6 \ Qwkhwlf - Hwv ( Pdqdwlqj Iurp & Lufxodu ( Oolswlfdo Dqg 5Hfwdqjxodu 1R ]] Ohv.” [21] J. S. Cano, G. D. Cordova, C. Narvaez, L. Segura, and L. Carrion, “Experimental study of the incidence of changing a synthetic jet orifice in heat transfer using a taguchi method approach,” J. Therm. Sci. Eng. Appl., vol. 11, no. 3, 2019, doi : 10.1115/1.4042351.

39. [22] L. Mangate , H. Yadav, A. Agrawal, and M. Chaudhari, “Experimental investigation on thermal and flow characteristics of synthetic jet with multiple-orifice of different shapes,” Int. J. Therm. Sci., vol. 140, no. February, pp. 344–357, 2019, doi : 10.1016/j.ijthermalsci.2019.02.036. [23] Y. H. Liu, T. H. Chang, and C. C. Wang, “Heat transfer enhancement of an impinging synthetic air jet using diffusion-shaped orifice,” Appl. Therm. Eng., vol. 94, pp. 178–185, 2016, doi : 10.1016/j.applthermaleng.2015.10.054. [24] A. Husin , M. Z. Abdullah, A. Ismail, A. A. Janvekar , M. S. Rusdi , and W. M. A. W. M. Ali, “Heat transfer performance of a synthetic jet generated by diffuser-shaped orifice,” J. Adv. Res. Fluid Mech. Therm. Sci., vol. 53, no. 1, pp. 122–128, 2019. [25] O. Işil , B. Yücesan , and M. Arik, “Impact of Orifice Size over Mechanical, Flow and Thermal Performances of Synthetic Jets,” Proc. 17th Intersoc . Conf. Therm. Thermomechanical Phenom. Electron. Syst. ITherm 2018, pp. 164–170, 2018, doi : 10.1109/ITHERM.2018.8419619. [26] P. Ziadé , M. A. Feero , and P. E. Sullivan, “A numerical study on the influence of cavity References RAKESH NANDAN IIT BHUBANESWAR, SMS PAGE NUMBER : 32

40. Length of fin 50 mm 2 mm

41. Length of fin Variation of temperature along the axial length Fin length (mm) 5 0.97 10 0.95 15 0.93 20 0.91 25 0.9 30 0.88 35 0.87 40 0.87 45 0.86 50 0.86 Fin length (mm) 5 0.97 10 0.95 15 0.93 20 0.91 25 0.9 30 0.88 35 0.87 40 0.87 45 0.86 50 0.86

42. Temperature variation along fin (Numerical) Source: Forced convection cooling of pcm based heat sink using synthetic jet. M.Tech thesis by Kartik Rajput, IIT BBSR.

43. Thermocouple positions and fin geometry Plate fin Cylindrical fin with cylindrical cavity Square fin with cylindrical cavity

44. Fin gap The distance between the fin should be determined by the thermal boundary layer formed during the natural convection. L L/2 (condition)       For this study the was found be: 0.81 mm  

45. 3D model of experimental setup

46. Actual picture of heat sink assembly

47. Fins geometry comparison Heat sink Volume (fin) mm^3 Volume ( pcm ) mm^3 Empty volume (mm^3) PCM contact surface (mm^2) Surface in contact with ambient (mm^2) Total surface area (mm^2) Plate fin 11232 18900 13608 6364.8 9036 15400.8 Cylindrical fin 6090.29 18925 18724.71 6927.8 6959.6 13887.4 Circular hole in square fin 12884 18925 11931 6927.8 9943.331 16871.131

48. Time taken to reach 50°C at varying power input for different heat sinks without PCM Time taken to reach 46°C (before melting) at varying power input for different heat sink filled with 1-Hexadecanol

49. Time taken to reach 52°C (while melting) at varying power input for different heat sink filled with 1-Hexadecanol Time taken to reach 58°C (after melting) at varying power input for different heat sink filled with 1-Hexadecanol

50. Time taken to reach 46°C (before melting) at varying power input for different heat sink with and without PCM Steady state temperature comparison of heat sinks with and without PCM

51. Synthetic jet Isometric view of synthetic jet Jet formulation criteria ( JFC ): Stokes number Strouhal number  

52. Cyclic load After the PCM is melted , the generated heat is not absorbed as latent heat . Then temperature of the heat sink base rises exponentially afterward. The advantage of PCM based heat sink is negated once the PCM is melted . So after the PCM is melted, it should be allowed to cool. The behavior of the PCM-based heat sink in cyclic loading must be studied . Heating time 45 min and cooling time 7 min Heating time 45 min and cooling time 15 min Heating time 45 min and cooling time 22.5 min Different type of cyclic loads considered for study