An Experimental Study of a Multi-Device Jet Impingement Cooler With Phase Change Using HFE-7100

2013 ◽  
Author(s):  
Shailesh N. Joshi ◽  
Matthew J. Rau ◽  
Ercan M. Dede ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Phase Change ◽  
Jet Impingement ◽  
Heat Fluxes ◽  
Orifice Diameter ◽  
Working Fluid ◽  
Dielectric Fluid ◽  
Automotive Electronics ◽  
Impingement Cooling

Jet impingement cooling with phase change has shown the potential to meet the increased cooling capacity demands of high-power-density (of order 100 W/cm2) automotive electronics components. In addition to improved heat transfer, phase change cooling has the potential benefit of providing a relatively isothermal cooling surface. In the present study, two-phase jet impingement cooling of multiple electronic devices is investigated, where the fluorinated dielectric fluid HFE-7100 is used as the working fluid. Four different types of jet arrays, namely, a single round jet with orifice diameter of 3.75 mm, and three different 5 × 5 arrays of round jets with orifice diameters of 0.5 mm, 0.6 mm and 0.75 mm, were tested and compared for both heat transfer and pressure drop. The experimental Reynolds number at the orifice ranged from 1860 to 9300. The results show that for the same orifice pressure drop, the single jet reached CHF at approximately 60 W/cm2, while the 5 × 5 array (d = 0.75 mm) safely reached heat fluxes exceeding 65 W/cm2 without reaching CHF. Additionally, the experimental results show that the multi-device cooler design causes an unintended rise in pressure inside the test section and a subsequent increase in sub-cooling from 10 K to 23.3 K.

scholarly journals Experimental Investigation of Embedded Micropin-Fins for Single-Phase Heat Transfer and Pressure Drop

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Chirag R. Kharangate ◽  
Ki Wook Jung ◽  
Sangwoo Jung ◽  
Daeyoung Kong ◽  
Joseph Schaadt ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Integrated Circuit ◽  
Single Phase ◽  
Absolute Error ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pin Fin

Three-dimensional (3D) stacked integrated circuit (IC) chips offer significant performance improvement, but offer important challenges for thermal management including, for the case of microfluidic cooling, constraints on channel dimensions, and pressure drop. Here, we investigate heat transfer and pressure drop characteristics of a microfluidic cooling device with staggered pin-fin array arrangement with dimensions as follows: diameter D = 46.5 μm; spacing, S ∼ 100 μm; and height, H ∼ 110 μm. Deionized single-phase water with mass flow rates of m˙ = 15.1–64.1 g/min was used as the working fluid, corresponding to values of Re (based on pin fin diameter) from 23 to 135, where heat fluxes up to 141 W/cm2 are removed. The measurements yield local Nusselt numbers that vary little along the heated channel length and values for both the Nu and the friction factor do not agree well with most data for pin fin geometries in the literature. Two new correlations for the average Nusselt number (∼Re1.04) and Fanning friction factor (∼Re−0.52) are proposed that capture the heat transfer and pressure drop behavior for the geometric and operating conditions tested in this study with mean absolute error (MAE) of 4.9% and 1.7%, respectively. The work shows that a more comprehensive investigation is required on thermofluidic characterization of pin fin arrays with channel heights Hf < 150 μm and fin spacing S = 50–500 μm, respectively, with the Reynolds number, Re < 300.

Flow Boiling Heat Transfer in a Silicon Microchannel Heat Sink Using Liquid Crystal Thermography

2008 ◽  
Author(s):  
Ayman Megahed ◽  
Ibrahim Hassan ◽  
Tariq Ahmad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Microchannel Heat Sink

The present study focuses on the experimental investigation of boiling heat transfer characteristics and pressure drop in a silicon microchannel heat sink. The microchannel heat sink consists of a rectangular silicon chip in which 45 rectangular microchannels were chemically etched with a depth of 295 μm, width of 254 μm, and a length of 16 mm. Un-encapsulated Thermochromic liquid Crystals (TLC) are used in the present work to enable nonintrusive and high spatial resolution temperature measurements. This measuring technique is used to provide accurate full and local surface-temperature and heat transfer coefficient measurements. Experiments are carried out for mass velocities ranging between 290 to 457 kg/m2.s and heat fluxes from 6.04 to 13.06 W/cm2 using FC-72 as the working fluid. Experimental results show that the pressure drop increases as the exit quality and the flow rate increase. High values of heat transfer coefficient can be obtained at low exit quality (xe < 0.2). However, the heat transfer coefficient decreases sharply and remains almost constant as the quality increases for an exit quality higher than 0.2.

Microelectromechanical System-Based Evaporative Thermal Management of High Heat Flux Electronics

2005 ◽  
Vol 127 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Cristina H. Amon ◽  
S.-C. Yao ◽  
C.-F. Wu ◽  
C.-C. Hsieh
Keyword(s):  
Microelectromechanical Systems ◽  
Surface Texturing ◽  
Jet Impingement ◽  
Heat Fluxes ◽  
Future Research ◽  
Dielectric Fluid ◽  
Practical Implementation ◽  
High Heat Flux ◽  
Droplet Impingement ◽  
Impingement Cooling

This paper describes the development of embedded droplet impingement for integrated cooling of electronics (EDIFICE), which seeks to develop an integrated droplet impingement cooling device for removing chip heat fluxes over 100W/cm2, employing latent heat of vaporization of dielectric fluids. Micromanufacturing and microelectromechanical systems are used as enabling technologies for developing innovative cooling schemes. Microspray nozzles are fabricated to produce 50–100 μm droplets coupled with surface texturing on the backside of the chip to promote droplet spreading and effective evaporation. This paper examines jet impingement cooling of EDIFICE with a dielectric coolant and the influence of fluid properties, microspray characteristics, and surface evaporation. The development of micronozzles and microstructured surface texturing is discussed. Results of a prototype testing of swiss-roll swirl nozzles with dielectric fluid HFE-7200 on a notebook PC are presented. This paper also outlines the challenges to practical implementation and future research needs.

On Development of a Semi-Mechanistic Wall Boiling Model

2013 ◽  
Author(s):  
Saurish Das ◽  
Hemant Punekar
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Stresses ◽  
Cooling System ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Wall Heat Transfer ◽  
Cooling Systems ◽  
Transfer Phenomenon

In modern cooling systems the requirement of higher performance demands highest possible heat transfer rates, which can be achieved by controlled nucleate boiling. Boiling based cooling systems are gaining attention in several engineering applications as a potential replacement of conventional single-phase cooling system. Although the controlled nucleate boiling enhances the heat transfer, uncontrolled boiling may lead to Dry Out situation, adversely affecting the cooling performance and may also cause mechanical damage due to high thermal stresses. Designing boiling based cooling systems requires a modeling approach based on detailed fundamental understanding of this complex two-phase heat and mass transfer phenomenon. Such models can help analyze different cooling systems, detect potential design flaws and carry out design optimization. In the present work a new semi-mechanistic wall boiling model is developed within commercial CFD solver ANSYS FLUENT. A phase change mechanism and wall heat transfer augmentation due to nucleate boiling are implemented in mixture multiphase flow framework. The phase change phenomenon is modeled using mechanistic evaporation-condensation model. Enhancement of wall heat transfer due to nucleate boiling is captured using 1D empirical correlation, modified for 3D CFD environment. A new method is proposed to calculate the local suppression of nucleate boiling based on the flow velocity, and hence this model can be applied to any complex shaped coolant passage. For different wall superheat, the wall heat fluxes predicted by the present model are validated against experimental data, in which 50-50 volume mixture of aqueous ethylene glycol (a typical anti-freeze coolant mixture) is used as working fluid. The validation study is performed in ducts of different sizes and shapes with different inlet velocities, inlet sub-cooling and operating pressures. The results are in good agreement with the experiments. This model is applied to a typical automobile Exhaust Gas Recirculation (EGR) system to study boiling heat transfer phenomenon and the results are presented.

Experimental Investigation of Area Ratio on Microjet Array Heat Transfer

2009 ◽  
Author(s):  
Gregory J. Michna ◽  
Eric A. Browne ◽  
Yoav Peles ◽  
Michael K. Jensen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Electronics Cooling ◽  
Jet Impingement ◽  
Area Ratio ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Transfer Performance ◽  
Transfer Coefficients ◽  
High Heat Transfer

Electronics cooling is becoming increasingly difficult due to increasing power consumption and decreasing size of processor chips. Heat fluxes in processors and power electronics are quickly approaching levels that cannot be easily addressed by forced air convection over finned heat sinks. Jet impingement cooling offers high heat transfer coefficients and has been used effectively in conventional-scale applications such as turbine blade cooling and the quenching of metals. However, literature in the area of microjet arrays is scarce and has not studied arrays of large area ratios. Hence, the objective of this study is to experimentally assess the heat transfer performance of arrays of microjets. The microjet arrays were fabricated using MEMS processes in a clean room environment. The heat transfer performance of several arrays using deionized water as the working fluid was investigated. Inline and staggered array arrangements were investigated, and the area ratio (total area of the jets divided by the surface area) was varied between 0.036 and 0.35. Reynolds numbers defined by the jet diameter were in the range of 50 to 3,500. Heat fluxes greater than 1,000 W/cm2 were obtained at fluid inlet-to-surface temperature differences of less than 30 °C. Heat transfer performance improved as the area ratio was increased.

Preliminary Results of Pressure Drop Modeling During Flow Boiling in Open Microchannels With Uniform and Tapered Manifolds (OMM)

2013 ◽  
Author(s):  
Ankit Kalani ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Flow Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Full Potential ◽  
Transfer Coefficients ◽  
Open Microchannel

Flow boiling with microchannel can dissipate high heat fluxes at low surface temperature difference. A number of issues, such as instabilities, low critical heat flux (CHF) and low heat transfer coefficients, have prevented it from reaching its full potential. A new design incorporating open microchannels with uniform and tapered manifold (OMM) was shown to mitigate these issues successfully. Distilled, degassed water at 80 mL/min is used as the working fluid. Plain and open microchannel surfaces are used as the test sections. Heat transfer and pressure drop performance for uniform and tapered manifold with both the surfaces are discussed. A low pressure drop of 7.5 kPa is obtained with tapered manifold and microchannel chip at a heat flux of 263 W/cm2 without reaching CHF. The pressure drop data is further compared with the homogenous model and the initial results are presented.

scholarly journals Heat Transfer Enhancement in Microchannel Flow: Presence of Microparticles in a Fluid

2010 ◽  
Author(s):  
Awad B. S. Alquaity ◽  
Salem A. Al-Dini ◽  
Evelyn N. Wang ◽  
Shahzada Z. Shuja ◽  
Bekir S. Yilbas ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Pressure Drop ◽  
Phase Change ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Microchannel Flow ◽  
Carrier Fluid ◽  
Volume Fractions ◽  
Energy Equations

In the present study, a numerical model was developed for laminar flow in a microchannel with a suspension of microsized phase change material (PCM) particles. In the model, the carrier fluid and the particles are simultaneously present, and the mass, momentum, and energy equations are solved for both the fluid and particles. The particles are injected into the fluid at the inlet at a temperature equal to the temperature of the carrier fluid. A constant heat flux is applied at the bottom wall. The temperature distribution and pressure drop in the microchannel flow were predicted for lauric acid microparticles in water with volume fractions ranging from 0 to 8%. The particles show heat transfer enhancements by decreasing the temperature distribution in the working fluid by 39% in a 1 mm long channel. Meanwhile, particle blockage in the flow passage was found to have a negligible effect on pressure drop in the range of volume fractions studied. This work is a first step towards providing insight into increasing heat transfer rates with phase change-based microparticles for applications in microchannel cooling and solar thermal systems.

scholarly journals Sweeping jet impingement heat transfer on a simulated turbine vane leading edge

2018 ◽  
Vol 2 ◽  
pp. 5A7OAZ ◽  
Author(s):  
Mohammad A. Hossain ◽  
Lucas Agricola ◽  
Ali Ameri ◽  
James W. Gregory ◽  
Jeffrey P. Bons
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Guide Vane ◽  
Leading Edge ◽  
Jet Impingement ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Impingement Cooling ◽  
Steady Jets

With the development of additive manufacturing technology, it is now possible to design complex and integrated internal cooling architecture for a gas turbine engine. In search of a spatially uniform heat transfer at the leading edge of a turbine nozzle guide vane, a sweeping jet impingement cooling strategy was proposed. Experiments were conducted in a low-speed wind tunnel to investigate sweeping jet impingement cooling in a faired cylinder leading edge model at an engine-relevant Biot number (Bi). Sweeping jets were generated with additively manufactured fluidic oscillator and steady jets were produced by a cylindrical orifice (with length to diameter ratio of 1). Both sweeping and steady jets were studied at varying mass flow rates, jet-to-wall spacing (H/D), jet pitch (P/D), and freestream turbulence. The effect of varying aspect ratio (AR) of the sweeping jet geometries was also studied. The overall cooling effectiveness of each configuration was estimated using infrared thermography (IR) measurements of the external surface temperature of the leading edge model. The sweeping jet provided higher overall cooling effectiveness values compared to steady jet in specific configurations. The pressure drop across each jet was also measured for each geometry, and the sweeping jet shows comparable pressure drop to steady jet.

Optimization of Hybrid-Linked Jet Impingement Cooling Channels Based on Response Surface Methodology and Genetic Algorithm

2017 ◽  
Author(s):  
Li Yang ◽  
Zheng Min ◽  
Sarwesh Narayan Parbat ◽  
Minking K. Chyu
Keyword(s):  
Heat Transfer ◽  
Genetic Algorithm ◽  
Response Surface Methodology ◽  
Pressure Drop ◽  
Response Surface ◽  
Flow Rate ◽  
Jet Impingement ◽  
Optimization Strategy ◽  
Impingement Cooling ◽  
Cooling Channels

In recent years, development of new manufacturing technologies like additive manufacturing has made it possible to make complex cooling structures to improve the efficiency of jet impingement. Present paper considers hybrid-linked jet impingement cooling channels which involve both parallel linked jets and serial linked jets. Systematic analysis was conducted with the aid of Computational Fluid Dynamics and Response Surface Methodology, focusing on the influence of topology on performance. An optimization platform was established with aid of the regressed database and the Genetic Algorithm. Of particular interest is the influence of optimization strategies on results. Results obtained indicates that the topology number developed in this study works well with the Response Surface Methodology. Topology can be considered to be a new degree of freedom of jet impingement design. Among the tested topologies, serial linked jet impingement has significantly higher heat transfer and pressure drop than the traditional parallel linked jet impingement. In the first optimization strategy, mass flow rate was used as the objective function while heat transfer and pressure drop were constrained. Optimized results under this strategy show consistent parameters and purely serial linked topology for all cases, due to the high cooling efficiency of serial linked jets. In the second optimization strategy, pressure drop was minimized while heat transfer and mass flow rate were constrained. Contrast with the first strategy, optimal results of this strategy have different topologies under different constraint conditions, which is caused by the complex influence of geometric parameters on pressure drop. Such results indicate the capability of hybrid-linked jet impingement to fit a wide various requirement by changing topology.

MEMS-Based Spatial and Temporal Thermal Management of High Heat Flux Electronics

2003 ◽  
Author(s):  
Cristina H. Amon ◽  
S. C. Yao
Keyword(s):  
Thermal Management ◽  
Surface Texturing ◽  
Jet Impingement ◽  
Heat Fluxes ◽  
Dielectric Fluid ◽  
Practical Implementation ◽  
High Heat Flux ◽  
Droplet Impingement ◽  
Micro Manufacturing ◽  
Impingement Cooling

This presentation describes the development of EDIFICE: Embedded Droplet Impingement For Integrated Cooling of Electronics. The EDIFICE project seeks to develop an integrated droplet impingement cooling device for removing chip heat fluxes over 100 W/cm2, employing latent heat of vaporization of dielectric fluids. Micro-manufacturing and MEMS (Micro Electro-Mechanical Systems) will be discussed as enabling technologies for innovative cooling schemes recently proposed. Micro-spray nozzles are fabricated to produce 50–100 micron droplets coupled with surface texturing on the backside of the chip to promote droplet spreading and effective evaporation. A novel feature to enable adaptive on-demand cooling is MEMS sensing (on-chip temperature, remote IR temperature and ultrasonic dielectric film thickness) and MEMS actuation. EDIFICE is integrated within the electronics package and fabricated using advanced micro-manufacturing technologies (e.g., Deep Reactive lon Etching (DRIE) and CMOS CMU-MEMS). The development of EDIFICE involves modeling, CFD simulations, and physical experimentation on test beds. This lecture will then examine jet impingement cooling of EDIFICE with a dielectric coolant and the influence of fluid properties, micro spray characteristics, and surface evaporation. The development of micro nozzles, micro-structured surface texturing, and the system integration of the evaporator is discussed. Results of a prototype testing of swirl nozzles with dielectric fluid HFE-7200 on a notebook PC are presented. This paper also reviews liquid and evaporative cooling research applied to thermal management of electronics. It outlines the challenges to practical implementation and future research needs.

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