High Water‐Absorbent and Phase‐Change Heat Dissipation Materials Based on Super‐Aligned Cross‐Stack CNT Films

2019 ◽  
Vol 21 (5) ◽  
pp. 1801216 ◽  
Author(s):  
Wei Yu ◽  
Changhong Liu ◽  
Shoushan Fan
Keyword(s):  
Phase Change ◽  
Heat Dissipation ◽  
High Water

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

Ceramic-Based Planar Heat Pipe (Plate) for Passive Electronics Cooling

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000159-000165
Author(s):  
M. Wilson ◽  
H. Anderson ◽  
J. Fellows ◽  
C. Lewinsohn
Keyword(s):  
Integrated Circuits ◽  
Phase Change ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Electronics Cooling ◽  
Ceramic Materials ◽  
Back Side ◽  
Dimensional Network ◽  
Internal Networks

Heat dissipation has become a major hurdle for the electronics industry, especially as higher performance integrated circuits are being developed for the power industry. Two of the primary hurdles in dissipating this heat are:The thermal contact resistance between the IC and the cooling device.The ability to effectively spread the heat, such that traditional cooling technologies can be effective.By selecting ceramic materials that are thermo-mechanically matched (CTE) to IC materials, the proposed heat plate can be directly bonded by typical solder or braze techniques to the back-side of the IC. This eliminates thermal resistances due to contact and thermal interface materials. Within these heat plates, a three dimensional network of gas channels and fluid wicks spread the high-flux heat loads from localized hot spots to the surrounding regions via phase change fluids and mass transport. Like traditional heat pipes, these heat plates operate at nearly uniform temperature due to the phase change. The internal networks provide for multidimensional heat and mass flow, increasing their dissipating capability. By using matched ceramic materials, and the inclusion of a heat plate, these primary hurdles for heat dissipation can be mitigated. The performance of prototypical planar heat plates will be presented.

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.

Characterizing the Stability of Carbon Nanotube Enhanced Water as a Heat Transfer Nanofluid

2010 ◽  
Author(s):  
Brian K. Ryglowski ◽  
Randall D. Pollak ◽  
Young W. Kwon
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Phase Change ◽  
Heat Dissipation ◽  
Coolant Fluid ◽  
Conductivity Enhancement ◽  
Design Variables ◽  
The Stability ◽  
The Many

Heat dissipation is a major challenge for many technologies. Possible solutions include thermal energy transfer via coolant fluid to a phase change material (PCM), with higher thermal conductivity a design goal. In recent years, heat transfer nanofluids (fluids with suspended nanoparticles) have received attention based on their potential for improving thermal conductivity. Carbon nanotubes (CNTs) are an attractive additive due to their enhanced thermal conductivity and ability to remain suspended over long times. However, characterizing their potential is difficult due to the many design variables and the need for repeated thermal conductivity tests for comparison. Since thermal conductivity enhancement is dependent on a dispersed nanotube network, the electrical conductivity of CNTs can be exploited to monitor the stability of such nanofluids, as such testing is quick and simple. The aim of this research was to evaluate electrical conductivity testing as a means to monitor stability of CNT-enhanced distilled water as a PCM, with varying CNT size, type, and concentration; and various other processing variables. The prepared nanofluids were tested after repeated phase change cycles. Results indicate that electrical conductivity testing is a practical means of monitoring the nanofluid stability, and CNT-based nanofluids show both promise and limitations as a PCM.

Research on Thermal Storage Effect of Floor Heating System with Phase Change Energy Storage

2012 ◽  
Vol 512-515 ◽  
pp. 2904-2907
Author(s):  
Guo Hui Feng ◽  
Kai Liang Huang ◽  
Xin Liu ◽  
Hui Xing Li
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Heat Dissipation ◽  
Thermal Storage ◽  
Heating System ◽  
Hot Water ◽  
Double Layers ◽  
Material Research ◽  
Storage Effect ◽  
Floor Heating

The floor heating system of phase change energy storage (FHSPC), performing well in storing and releasing thermal energy, plays a significant role in using solar energy and low-priced nocturnal electrical power for heating. However, due to such problems as ineffective package and insufficient overall integration of phase change material, research of FHSPC has not made progress in practical application. This paper researches thermal storage effect of a new floor heating system of phase change energy storage using solar hot water as the heat source and double layers of capillary network as the heat dissipation end. Differential scanning calorimeter was used to choose capric acid as the main energy storage material. For a steady heating cycle of heating for 8 hours and releasing for 16 hours, acceptable thermal condition is observed in the test room. The new FHSPC could provide long span intermittent heating with little heat loss, therefore the intermittent energy source can be well utilized

scholarly journals Investigation of Thermal Properties of Novel Phase Change Material Mixtures (Octadecane-Diamond) with Laser Flash Analysis

2019 ◽  
Vol 26 (4) ◽  
pp. 211-218
Author(s):  
Mateusz Sierakowski ◽  
Wojciech Godlewski ◽  
Roman Domański ◽  
Jakub Kapuściński ◽  
Tomasz Wiśniewski ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Phase Change ◽  
Power Plants ◽  
Large Scale ◽  
Phase Change Materials ◽  
Heat Dissipation ◽  
Electronics Cooling ◽  
Diamond Powder ◽  
Heat Of Fusion

AbstractPhase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.

scholarly journals Simulation of heat dissipation model of lithium-ion battery pack

2021 ◽  
Vol 300 ◽  
pp. 01014
Author(s):  
Maode Li ◽  
Chuan He ◽  
Jinkui Zheng
Keyword(s):  
Phase Change ◽  
Temperature Rise ◽  
Heat Dissipation ◽  
Lithium Ion ◽  
Maximum Temperature ◽  
Air Cooling ◽  
Power Battery ◽  
Staggered Arrangement ◽  
Dissipation Model ◽  
Cooling Methods

Lithium-ion power battery has become an important part of power battery. According to the performance and characteristics of lithiumion power battery, the influence of current common charge and discharge and different cooling methods on battery performance was analysed in this paper. According to the software simulation, in the 5C charge-discharge cycle, the maximum temperature of the cells with regular arrangement is 57.97°C, the maximum temperature of the cells with staggered arrangement is 55.83°C, and the maximum temperature of phase change cooling is 47.42°C. The most important thing is that the temperature difference between the cells with phase change cooling is only 5.5°C. Some simulation results of air cooling and phase change show that phase change cooling can control the heat dissipation and temperature rise of power battery well. The research in this paper can provide better theoretical guidance for the temperature rise, heat transfer and thermal management of automotive power battery.

Sign in / Sign up

Export Citation Format

Share Document