scholarly journals Investigation of the Thermal Performance of Salt Hydrate Phase Change of Nanoparticle Slurry Flow in a Microchannel

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Safi A. Memon ◽  
M. B. Sajid ◽  
M. S. Malik ◽  
Awad B. S. Alquaity ◽  
M. Mohib ur. Rehman ◽  
...  
Keyword(s):  
Phase Change ◽  
Thermal Performance ◽  
Lauric Acid ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Computational Study ◽  
Operating Conditions ◽  
Slurry Flow ◽  
Design Guideline ◽  
Salt Hydrate

Computational study was conducted to investigate the thermal performance of water-based salt hydrate S44 nanoparticles as the phase change material (PCM) in a microchannel heat sink. Constant heat dissipation was applied on the top wall of the heat sink. Forced internal convection of the PCM slurry flow was performed through a homogeneous approach. Three thermal performance parameters, including effectiveness ratio, performance index, and Merit number, were used to quantify the cooling performance of S44 for various concentrations of the PCM nanoparticles. The thermal performance of the salt hydrate S44 slurry was also compared with a similar study conducted for lauric acid nanoparticle slurry found in the literature. Specific operating conditions were identified. The salt hydrate S44 would provide better thermal performance than lauric acid, and vice versa. Finally, Nusselt number correlations have been developed for the microchannel PCM heat sink for Reynolds numbers in the range 12.23 to 47.14 and Prandtl numbers in the range 3.74 to 5.30. A design guideline for manufacturing PCM particles and microchannel heat sinks is provided. With this guideline, the heat absorption ability of the heat sink is maximized, and the pumping power and the losses related to the addition of the particles are minimized.

Thermal and Structural Response of Pin Fins for Different Interface Conditions

2010 ◽  
Author(s):  
Abul Fazal M. Arif ◽  
Sulaman Pashah ◽  
Syed M. Zubair ◽  
M. Inam
Keyword(s):  
Thermal Performance ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Structural Response ◽  
Operating Conditions ◽  
Stress Fields ◽  
Power Device ◽  
Interface Conditions ◽  
Thermal Interface ◽  
Pin Fin

Thermal management of electronic products relies on the effective dissipation of heat. Heat sink elements (e.g. a pin fin) are used for any effective heat dissipation network. Despite much optimized design of the heat sink element, the heat transfer may not be effective because the interface between power device and heat sink element is critical in the heat dissipation network. Thermal Interface Materials TIM (e.g. adhesive, solder, pads, or pastes) are employed at interface between power device and heat sink element to minimize the interface thermal resistance. However, several challenges need to be addressed before they can be successfully utilized because depending on the thermal interface conditions, the thermal stress level can attain undesirable values. This issue can be addressed by the optimization of the system design with the help of simulation methods. Generally the effects of interface conditions are studied on the thermal performance of the heat sink system whereas in this paper, a coupled-field (thermal-structural) analysis using FEM is performed to study the thermal as well as structural behavior of the heat sink system. Temperature variation and stress fields in the region of interface between pin fin and base plate are analyzed. Effects of various parameters (such as contact pressure, surface roughness, TIM thickness, and operating conditions) on the resulting thermal and structural response at the interface are presented. It has been found that different interface conditions may have comparable thermal performance with significant different stress fields at the interface. Therefore stress state must be known to ensure the structural integrity of the heat sink system for a given operating condition.

Thermal Behaviors of Passively-Cooled Hybrid Fin Heat Sinks for Lightweight and High Performance Thermal Management

2015 ◽  
Author(s):  
Nico Setiawan Effendi ◽  
Kyoung Joon Kim
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
High Performance ◽  
Heat Dissipation ◽  
Computational Study ◽  
Heat Sinks ◽  
Channel Diameter ◽  
Internal Channel ◽  
Study Results ◽  
Parametric Effects

A computational study is conducted to explore thermal performances of natural convection hybrid fin heat sinks (HF HSs). The proposed HF HSs are a hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS). Parametric effects such as a fin spacing, an internal channel diameter, a heat dissipation on the performance of HF HSs are investigated by CFD analysis. Study results show that the thermal resistance of the HS increases while the mass-multiplied thermal resistance of the HS decreases associated with the increase of the channel diameter. The results also shows the thermal resistance of the SHF HS is 13% smaller, and the mass-multiplied thermal resistance of the HHF HS is 32% smaller compared with the pin fin heat sink (PF HS). These interesting results are mainly due to integrated effects of the mass-reduction, the surface area enhancement, and the heat pumping via the internal channel. Such better performances of HF HSs show the feasibility of alternatives to the conventional PF HS especially for passive cooling of LED lighting modules.

Thermal performance of a phase change material-based heat sink in presence of nanoparticles and metal-foam to enhance cooling performance of electronics

2022 ◽  
Vol 48 ◽  
pp. 103882
Author(s):  
Adeel Arshad ◽  
Mark Jabbal ◽  
Hamza Faraji ◽  
Pouyan Talebizadehsardari ◽  
Muhammad Anser Bashir ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Thermal Performance ◽  
Heat Sink ◽  
Metal Foam ◽  
Cooling Performance ◽  
Change Material

Copper-Carbon Nanotube Micropillars for Passive Thermal Management of High Heat Flux Electronic Devices

2020 ◽  
Author(s):  
Gerardo Rojo ◽  
Jeff Darabi
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Computational Study ◽  
Copper Substrate ◽  
Heat Removal ◽  
Cost Effective ◽  
High Heat ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Micropillar Array

Abstract Miniaturization of electronic products and a consequent rapid increase in power density of advanced microprocessors and electronic components have created a need for improved cooling techniques to efficiently remove heat from such devices. Traditional air-cooled heat sinks have been utilized for several decades as the most cost-effective cooling technique for electronic cooling applications. However, the existing thermal management solutions are unable to maintain the temperature of the next generation of complex electronic systems within acceptable limits without adding considerable weight and complexity. This paper reports a microstructured wick for application in passive thermal management systems such as heat pipes and vapor chambers. The wick structure consists of mushroom-like composite copper-carbon nanotubes (Cu-CNT) micropillars. The small spacing between micropillar heads provides a higher capillary pressure whereas the large spacing between the base of micropillars provides a higher permeability for liquid flow. The micropillar array was fabricated on a copper substrate using an electroplating technique. The micropillar array was then tested in a controlled environment to experimentally measure its thermal performance under several operating conditions. A heat removal capability of 80 W/cm2 was demonstrated at a wall superheat of 15° C. In addition, a computational study was performed using ANSYS Fluent to predict the thermal performance of the micropillar array. Model predictions were compared with the experimental results and good agreement was obtained.

Experimental Investigation of a PCM-Based Topology Optimized Heat Sink for Passive Cooling of Electronics

2020 ◽  
Author(s):  
Jin Yao Ho ◽  
Kai Choong Leong
Keyword(s):  
Thermal Performance ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Base Temperature ◽  
Storage Unit ◽  
Cooling Of Electronics

Abstract A thermal energy storage unit filled with phase change material (PCM) can serve as a heat sink for the cooling of electronics with intermittent or periodic heat dissipation rates. The use of thermal conductive structures (TCS) is an effective method of improving the thermal performance of a PCM-based heat sink. In this paper, topology optimization is explored to develop a new class of TCS with a tree-like structure to enhance the thermal performance of a trapezoidal heat sink. The topology-optimized heat sink was then fabricated by Selective Laser Melting (SLM) using an aluminum alloy, AlSi10Mg, as the base powder. Experiments were performed to evaluate the thermal performance of the topology-optimized heat sink with the tree-like structure. In addition, a conventional longitudinal-fin heat sink of the same solid volume fraction (φ = 16.2%) and a heat sink without enhanced structure were also fabricated and experimentally investigated for comparison. Rubitherm RT-35HC paraffin wax was used as the PCM. Three different heat fluxes of 4.00 kW/m2, 5.08 kW/m2 and 7.24 kW/m2 were applied at the base of each specimen by a silicone rubber heater. The structure wall and the PCM temperatures were measured over time. Our results show that, for all heat rates tested, the topology-optimized heat sink was able to maintain a lower base temperature as compared to the fin-structure and the plain heat sinks. A thermal enhancement ratio (ε) is defined to evaluate the performance of the heat sinks with and without the use of PCM. From the experimental results, the highest ε value of 8.6 was achieved by the topology-optimized heat sink. These results indicate the better performance of the topology-optimized heat sink in dissipating heat as compared to the other specimens.

scholarly journals Precise nanoscale temperature mapping in operational microelectronic devices by use of a phase change material

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qilong Cheng ◽  
Sukumar Rajauria ◽  
Erhard Schreck ◽  
Robert Smith ◽  
Na Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Dissipation ◽  
Radiation Thermometry ◽  
High Vacuum ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Scanning Thermal Microscopy ◽  
Change Material

AbstractThe microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs to be tested under the actual operating conditions. Therefore, the development of high-resolution thermometry techniques is required to understand the heat dissipation processes during the device operation. Recently, several thermometry techniques have been proposed, such as radiation thermometry, thermocouple based contact thermometry, scanning thermal microscopy, scanning transmission electron microscopy and transition based threshold thermometers. However, most of these techniques have limitations including the need for extensive calibration, perturbation of the actual device temperature, low throughput, and the use of ultra-high vacuum. Here, we present a facile technique, which uses a thin film contact thermometer based on the phase change material $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 , to precisely map thermal contours from the nanoscale to the microscale. $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 undergoes a crystalline transition at $$\hbox {T}_{{g}}$$ T g with large changes in its electric conductivity, optical reflectivity and density. Using this approach, we map the surface temperature of a nanowire and an embedded micro-heater on the same chip where the scales of the temperature contours differ by three orders of magnitude. The spatial resolution can be as high as 20 nanometers thanks to the continuous nature of the thin film.

scholarly journals Simulation and experimental study of phase change cooling and heating wall radiation air conditioning system

2020 ◽  
Vol 143 ◽  
pp. 02044
Author(s):  
Gao Chunxue ◽  
Wu Songlin ◽  
Lang Junqian ◽  
Liu Qiuxin
Keyword(s):  
Phase Change ◽  
Thermal Performance ◽  
Air Conditioning ◽  
Field Experiments ◽  
Thermal Environment ◽  
Operating Conditions ◽  
Operation Condition ◽  
Heating Wall ◽  
Air Conditioning System ◽  
Winter Operation

This paper presents a case study of phase change cooling and heating wall radiant (PC-CHWR) air conditioning system application in an energy-saving renovation project in a laboratory in Wuhan, Hubei province in China. To test the thermal performance of the system, the PHOENICS software was utilized to simulate and analyse the indoor thermal environment in the laboratory under both winter and summer operating conditions. In addition, field experiments were also conducted under winter operation condition. By comparing the results between numerical simulation and field experiment, it is found that thermal performance of the PC-CHWR air conditioning system evaluated by these two evaluation methods are quite match. Moreover, the results also show that the PC-CHWR system can meet the cooling and heating load of the building within the acceptable range.

Advanced Cooling With Embedded Heat Pipes for High Power Microelectronics

2009 ◽  
Author(s):  
Victor Adrian Chiriac
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Pipes ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Peak Temperature ◽  
Transient Temperature ◽  
Efficient Operation ◽  
The Impact

The transient thermal behavior of a complex testing system including multiple fans, a mixing enclosure, Cu inserts and a leaded package dissipating large amounts of power over short time durations is evaluated via numerical simulations. The system performance is optimized with heat sink/fan structure for device efficient operation under constant powering. The study provides meaningful understanding and prediction of a transient powering scenario at high powering levels, evaluating the impact of alternative cooling fan/heat pipe configurations on the thermal performance of the system. One design is chosen due to its effective thermal performance and assembly simplicity, with the package embedded in heat sink base with multiple (5) heat pipes. The peak temperature reached by the modified design with 4 cooling fans is ∼95°C, with the corresponding Rja thermal resistance ∼0.58°C/W. For the transient study (with embedded heat pipes and 4 fans), after one cycle, both peak temperature (at 45 s) and the end temperature (at 49 s) decrease as compared to the previous no heat pipe/single fan case (especially the end temperature reduces by ∼16%). The temperature drop between peak and end for each cycle is ∼80.2°C, while the average power per transient cycle is ∼31.27W. With this power, the design with 5 perpendicular heat pipes, 4 fans and insert reaches a steady state peak temperature of ∼98°C. Applying the superposition principle, the maximum transient temperature after a large number of operating cycles will not exceed ∼138.1°C, satisfying the thermal budget under the current operating conditions. The benefit of the study is related to the possibility to extract the maximum/minimum temperatures for a real test involving a large number of heating-cooling cycles, yet maintaining the initial and peak temperatures within a certain range for the optimal operation of the device. The flow and heat transfer fields are thoroughly investigated: using a combination of numerical and analytical study, the thermal performance of the device undergoing large number of periodic thermal cycles is predicted. Further comparison between measurement and simulation results reveals good agreement.

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