Development of a Hybrid PCM-Air Heat Sink

2011 ◽  
Author(s):  
Y. Kozak ◽  
B. Abramzon ◽  
G. Ziskind
Keyword(s):  
Melting Temperature ◽  
Thermal Management ◽  
Heat Sink ◽  
Power Dissipation ◽  
Phase Change Materials ◽  
Ambient Air ◽  
Significant Rise ◽  
Optical Systems ◽  
Base Temperature ◽  
Periodic Regime

The present study deals with the transient thermal management of electro-optical equipment using the phase-change materials (PCMs). These materials can absorb large amounts of heat without significant rise of their temperature during the melting process. This effect is attractive for using in the passive thermal management of portable electro-optical systems, particularly those where the device is intended to operate in the periodic regime, or where the relatively short stages of high power dissipation are followed by long stand-by periods without a considerable power release. In the present work, a so-called hybrid heat sink is developed. The heat sink is made of aluminum. The heat is dissipated on the heat sink base, and then is transferred by thermal conduction to the PCM and to a standard forced-convection air heat sink cooled by an attached fan. The whole system may be initially at some constant temperature which is below the PCM melting temperature. Then, power dissipation on the heat sink base is turned on. As heat propagates within the heat sink, some part of it is absorbed by the PCM causing a delay in the temperature growth at the heat sink base. Alternatively, the steady-state conditions may be such that the base temperature is below the PCM melting temperature, meaning that all the heat generated on the heat sink base is transferred to the cooling air. Then, the fan is turned off reducing the heat transfer to the ambient air, and the heat is absorbed into the PCM resulting in its melting. In both cases, the time that it will take the heat sink base to approach some specified maximum allowed temperature is expected to be longer than that without the PCM.

Enhanced Melting for Transient Thermal Management

2015 ◽  
Author(s):  
T. Rozenfeld ◽  
R. Hayat ◽  
Y. Kozak ◽  
G. Ziskind
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Close Contact ◽  
Heated Surface ◽  
Contact Melting ◽  
Significant Rise ◽  
Periodic Regime ◽  
Transient Thermal

The present study deals with transient thermal management using phase change materials (PCMs). These materials can absorb large amounts of heat without significant rise of their temperature during the melting process. This effect is attractive for passive thermal management, particularly where the device is intended to operate in a periodic regime, or where the relatively short stages of high power dissipation are followed by long stand-by periods without a considerable power release. Heat transfer in PCMs, which have low thermal conductivity, can be enhanced by fins that enlarge the heat transfer area. However, when the PCM melts, a layer of liquid is growing at the fins creating an increasing thermal resistance that impedes the process. The present work aims to demonstrate that performance of a latent-heat thermal management unit may be considerably affected by achieving a so-called close-contact melting (CCM), which occurs when the solid phase is approaching a heated surface, and only a thin liquid layer is separating between the two. Although CCM was extensively studied in the past, its possible role in finned systems has been revealed only recently by our group. In particular, it depends heavily on the specific configuration of the fins. In the present work, close-contact melting is modeled analytically for a geometry which includes two symmetrically inclined fins. A quasi-steady approach is used for calculating the rate of melting based on the force and energy balances. The results are expressed in terms of the time-dependent melt fraction and Nusselt number, showing their explicit dependence on the Stefan and Fourier numbers. Moreover, the approach used in the present study may be applied to other geometries in which the heated surface is not horizontal or where there are a number of heated surfaces or fins.

Analysis of a Hybrid PCM-Air Heat Sink

2012 ◽  
Author(s):  
Y. Kozak ◽  
B. Abramzon ◽  
G. Ziskind
Keyword(s):  
Melting Temperature ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Heat Removal ◽  
Melting Process ◽  
Significant Rise ◽  
Heat Accumulation ◽  
Forced Circulation ◽  
Compound Matrices ◽  
Conservative Estimation

Phase-change materials (PCMs) can absorb large amounts of heat without significant rise of their temperature during the melting process. This effect may be utilized in thermal energy storage and passive thermal management. In order to enhance the rate of heat transfer into PCMs, various techniques have been suggested, like fins, metal and graphite-compound matrices, dispersed high-conductivity particles inside the PCM, and micro-encapsulation. The present work deals with a hybrid PCM-air heat sink. The heat is dissipated on the heat sink base, and may be either absorbed by the PCM stored in compartments with conducting walls, or dissipated to the air using fins, or both. The heat sink is made of aluminum 6061. Eicosane (C20H42, 96% purity, nominal melting temperature 36.7°C) is used as the PCM. In order to exclude the effect of sensible heating below the melting temperature, a controllable environment is used. The latter is created in a programmable forced-circulation oven. A simplified thermal model is developed for a conservative estimation of temperature growth of the heat sink base. The results of this model are compared to the experimental results. The relative contributions of heat accumulation, both by latent and sensible heat, and of heat removal by air are presented and discussed.

Design and Thermal Characteristics of a Synthetic Jet Ejector Heat Sink

2004 ◽  
Vol 127 (2) ◽  
pp. 172-177 ◽  
Author(s):  
Raghav Mahalingam ◽  
Ari Glezer
Keyword(s):  
Thermal Resistance ◽  
Steady Flow ◽  
Heat Sink ◽  
Power Dissipation ◽  
Ambient Air ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Transfer Coefficients ◽  
Electromagnetic Actuators ◽  
Air Jet

The design and thermal performance of a synthetic-air-jet-based heat sink for high-power dissipation electronics is discussed. Each fin of a plate-fin heat sink is straddled by a pair of two-dimensional synthetic jets, thereby creating a jet ejector system that entrains cool ambient air upstream of the heat sink and discharges it into the channels between the fins. The jets are created by periodic pressure variations induced in a plenum by electromagnetic actuators. The performance of the heat sink is assessed using a thermal test die encased in a heat spreader that is instrumented with a thermocouple. The case-to-ambient thermal resistance under natural convection with the heat sink is 3.15°C∕W. Forced convection with the synthetic jets enables a power dissipation of 59.2W at a case temperature of 70°C, resulting in a case-to-ambient thermal resistance of 0.76°C∕W. The synthetic-jet heat sink dissipates ∼40% more heat compared to steady flow from a ducted fan blowing air through the heat sink. The synthetic jets generate a flow rate of 4.48 CFM through the heat sink, resulting in 27.8 W/CFM and thermal effectiveness of 0.62. The effect of fin length on the thermal resistance of the heat sink is discussed. Detailed measurements on an instrumented heat sink estimate that the average heat transfer coefficients in the channel flow between the fins is 2.5 times that of a steady flow in the ducts at the same Reynolds Number.

Detailed Numerical Modeling of a Hybrid PCM-Air Heat Sink

2013 ◽  
Author(s):  
Y. Kozak ◽  
G. Ziskind
Keyword(s):  
Numerical Modeling ◽  
Phase Change ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Void Formation ◽  
Solidification Process ◽  
Melting Process ◽  
Significant Rise ◽  
Air Interface ◽  
Vof Model

The ability of phase-change materials (PCMs) to absorb large amounts of heat without significant rise of their temperature during the melting process may be utilized in thermal energy storage and passive thermal management. This paper deals with numerical modeling of a hybrid PCM-air heat sink, in which heat may be either absorbed by the PCM stored in compartments with conducting walls, or dissipated to the air using fins, or both. Under the assumptions of perfect insulation (except for the air fins), identity and symmetry between all PCM channels, and negligible 3-D boundary effects, a 2-D model of the problem for half a PCM compartment of the heat sink is solved, saving calculation time and yet taking into account the essential physical phenomena. A commercial program, ANSYS Fluent, is used in order to solve the governing conservation equations. Phase-change is solved using the enthalpy-porosity method. PCM-air interface is modeled using the volume-of-fluid (VOF) approach. The model takes into account natural convection in the liquid PCM and air, volume change, phase- and temperature-dependence of thermal properties, and PCM-air interface interaction. Various scenarios for the hybrid heat sink operation are simulated and compared. The difference in the melting patterns is analyzed for the cases of heating with and without the fan operating. The solidification process with the fan operating is also simulated. It is shown that the VOF model enables simulating realistic void formation in the solidification process.

Cooling Technique for Outdoor Electronic Enclosures Using Phase Change Materials

2000 ◽  
Author(s):  
Hamid A. Hadim ◽  
Igbal Mehmedagic
Keyword(s):  
Phase Change ◽  
Thermal Management ◽  
Heat Sink ◽  
Phase Change Materials ◽  
Theoretical Study ◽  
Peak Load ◽  
Ambient Conditions ◽  
Moderate Amount ◽  
Ambient Temperatures ◽  
Cooling Technique

Abstract A theoretical study is conducted to investigate a new cooling technique for thermal management of outdoor telecommunication equipment enclosures. The technique consists of using a phase change material (PCM) combined with a heat sink to dissipate the heat to the ambient. The main advantages of using the PCM include: fully passive technique with no maintenance, no power is required, and relatively low cost. The use of the PCM for more effective thermal management of electronic enclosures is investigated for both the high end cooling (i.e. when the enclosure is exposed to high ambient temperatures) and the low end cooling (i.e. when the enclosure is exposed to very low ambient temperatures). The results from this preliminary theoretical study showed that with the use of a moderate amount of a properly selected PCM combined with the heat sink, the temperature within the enclosure can be maintained within the specified operating range. Potential applications with the use of the PCM include: peak load usage (e.g. during high communications traffic periods), extreme ambient conditions, reduced temperature fluctuations (to improve reliability), and more efficient implementation in smaller size enclosures.

Experimental Analysis of a Vapor Chamber Applied to Thermal Management of Microelectronics

2015 ◽  
Vol 1120-1121 ◽  
pp. 1368-1372 ◽  
Author(s):  
Daniel Henrique de Souza Obata ◽  
Thiago Antonini Alves ◽  
Márcio Antonio Bazani ◽  
Amarildo Tabone Paschoalini
Keyword(s):  
Thermal Management ◽  
Integrated Circuit ◽  
Heat Sink ◽  
Power Dissipation ◽  
Pure Aluminum ◽  
Experimental Tests ◽  
Working Fluid ◽  
Vapor Chamber ◽  
Airflow Velocity ◽  
Circuit Power

In this research, a vapor chamber embedded in the base of a heat sink was experimentally analyzed for the application in thermal management of microelectronics. The vapor chamber was produced by a copper and molybdenum alloy with length of 240 mm, width of 54 mm, thickness of 3 mm, and capillary structures composed by copper screen meshes. The working fluid used was de-ionized water. The pure aluminum heat sink was cooled by air forced convection and the evaporator vapor chamber was heated using an electrical resistor simulating integrated circuit power dissipation. The experimental tests were done in a suction type wind tunnel with open return for a heat load varying from 20 to 80 W and for an airflow velocity varying from 1 to 4 m/s. The experimental results showed that the considered vapor chamber worked successfully, maintaining low operating temperature.

scholarly journals A parametric investigation of a PCM-based pin fin heat sink

2015 ◽  
Vol 6 (1) ◽  
pp. 65-73 ◽  
Author(s):  
R. Pakrouh ◽  
M. J. Hosseini ◽  
A. A. Ranjbar
Keyword(s):  
Heat Sink ◽  
Phase Change Materials ◽  
Electronic Devices ◽  
Operating Time ◽  
Heat Sinks ◽  
Geometrical Parameters ◽  
Base Temperature ◽  
Pin Fin ◽  
Heat Transfer Calculation ◽  
Acceptable Agreement

Abstract. This paper presents a numerical investigation in which thermal performance characteristics of pin fin heat sinks enhanced with phase-change materials (PCMs) designed for cooling of electronic devices are studied. The paraffin RT44 HC is poured into the aluminum pin fin heat sink container, which is chosen for its high thermal conductivity. The effects of different geometrical parameters, including number, thickness and height of fins, on performance are analyzed. Different aspects for heat transfer calculation, including the volume expansion in phase transition as well as natural convection in a fluid zone, are considered in the study. In order to validate the numerical model, previous experimental data and the present results are compared, and an acceptable agreement between these two is observed. Results show that increasing the number, thickness and height of fins leads to a significant decrease in the base temperature as well as operating time of the heat sink.

CFD Optimization of Design for IGBT Air-Cooled Heat Sink

2012 ◽  
Vol 562-564 ◽  
pp. 755-758 ◽  
Author(s):  
Bo Xu ◽  
Xin Chun Lin ◽  
Li Peng
Keyword(s):  
Thermal Management ◽  
Parameter Optimization ◽  
Heat Sink ◽  
Power Dissipation ◽  
Junction Temperature ◽  
Insulated Gate Bipolar Transistor ◽  
Complex Design ◽  
Heat Parameter ◽  
Cfd Optimization ◽  
Current Systems

Power dissipation problems for Insulated Gate Bipolar Transistor (IGBT) are requiring increasingly complex design solutions. While designs that are more efficient make thermal management possible, current systems still require CFD methods for dissipating heat. Parameter optimization of the air-cooled heat sink is carried out to cool a three-chip, 2400w IGBT plate. The parameters are compared using maximum junction temperature and fan efficiency.

scholarly journals Thermal Performance Investigation of Slotted Fin Minichannel Heat Sink for Microprocessor Cooling

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6347
Author(s):  
Taha Baig ◽  
Zabdur Rehman ◽  
Hussain Ahmed Tariq ◽  
Shehryar Manzoor ◽  
Majid Ali ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Heat Removal ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Base Temperature ◽  
High Processing

Due to high heat flux generation inside microprocessors, water-cooled heat sinks have gained special attention. For the durability of the microprocessor, this generated flux should be effectively removed. The effective thermal management of high-processing devices is now becoming popular due to high heat flux generation. Heat removal plays a significant role in the longer operation and better performance of heat sinks. In this work, to tackle the heat generation issues, a slotted fin minichannel heat sink (SFMCHS) was investigated by modifying a conventional straight integral fin minichannel heat sink (SIFMCHS). SFMCHSs with fin spacings of 0.5 mm, 1 mm, and 1.5 mm were numerically studied. The numerical results were then compared with SIFMCHSs present in the literature. The base temperatures recorded for two slots per fin minichannel heat sink (SPFMCHS), with 0.5 mm, 1 mm, and 1.5 mm fin spacings, were 42.81 °C, 46.36 °C, and 48.86 °C, respectively, at 1 LPM. The reductions in base temperature achieved with two SPFMCHSs were 9.20 %, 8.74 %, and 7.39% for 0.5 mm, 1 mm, and 1.5 mm fin spacings, respectively, as compared to SIFMCHSs reported in the literature. The reductions in base temperature noted for three SPFMCHSs were 8.53%, 9.05%, and 5.95% for 0.5 mm, 1 mm, and 1.5 mm fin spacings, respectively, at 1 LPM, as compared to SIFMCHSs reported in the literature. In terms of heat transfer performance, the base temperature and thermal resistance of the 0.5 mm-spaced SPFMCHS is better compared to 1 mm and 1.5 mm fin spacings. The uniform temperature distribution at the base of the heat sink was observed in all cases solved in current work.

Experimental Investigation of Thermal Performance of Nano-Enhanced Phase Change Materials for Thermal Management of Electronic Components

2019 ◽  
Author(s):  
Rohit Kothari ◽  
Dattaraj V. Vaidya ◽  
Vinay Shelke ◽  
Santosh K. Sahu ◽  
Shailesh I. Kundalwal
Keyword(s):  
Experimental Investigation ◽  
Phase Change ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Heat Sinks ◽  
Melting Time ◽  
Management Technique ◽  
Base Temperature ◽  
Al2o3 Nanoparticles ◽  
Time Duration

Abstract Present experimental investigation focuses on implementing passive cooling thermal management technique using heat sinks filled with paraffin wax as phase change material (PCM). Al2O3 nanoparticles are dispersed as thermal conductivity enhancer (TCE) in different weight fractions (φ) for improved performance in the PCM. Unfinned and two finned heat sinks are used in this investigation. Experimental analysis is performed on different configurations of heat sinks and nano-enhanced phase change materials (NePCMs) consisting various weight fraction of Al2O3 nanoparticles (φ = 0%, 0.5%, 4%, and 6%) for a constant heat flux of 2.0 kW/m2. Results show that latent heat and specific heat capacity decreases with increase in the Al2O3 nanoparticle loading. Addition of Al2O3 nanoparticles in the PCM results in the reduced melting time of PCM. While, pure PCM based heat sinks keeps heat sink base temperature lower for longer time duration.

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