Analysis of the thermal mechanism and temporal and spatial evolution of the thermal field of deep sandstone under microwaves

In the practice of the deep engineering, it is expected to improve engineering efficiency by introducing the microwave energy. Therefore, based on 1050 m deep sandstone, the heating characteristics of sandstone and its constituent minerals in the microwave field are comprehensively explored through experiments and nu?merical simulations. In the paper, the asynchronism of the temperature rise in different areas of the sandstone depends on the local characteristics of dielectric loss and maximum heat storage capacity. With increase of the temperature, the evaporation of the water leads to the decrease of the dielectric properties, the increase in the constant-pressure heat capacity and the increase in the heat dissipation coefficient, which suppresses the temperature growth trend. The temperature rise of the amplitude of the material is lower than that expected from the microwave power. The maximum temperature of dolomite, feldspar and quartz under the power of 2000 W is 1.86, 1.71, and 1.63 times that of the power of 1000 W, respectively. It is necessary to select the reasonable microwave power to maximize the engineering efficiency. The results are expected to provide the theoretical and technical supports for the electromagnetic heat generation in deep engineering.

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Simulation of heat dissipation model of lithium-ion battery pack

E3S Web of Conferences ◽

10.1051/e3sconf/202130001014 ◽

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.

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Plastic Dissipation and Temperature Field around a Steady Running Crack

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.324-325.895 ◽

2006 ◽

Vol 324-325 ◽

pp. 895-898

Author(s):

Wen Bo Luo ◽

Ting Qing Yang

Keyword(s):

Temperature Field ◽

Heat Source ◽

Plastic Zone ◽

Temperature Rise ◽

Heat Dissipation ◽

Crack Tip ◽

Maximum Temperature ◽

Growth Speed ◽

Density Distribution Function ◽

Plastic Dissipation

Temperature field is formed due to heat dissipation when material is subjected to irreversible deformation. In this paper, the heat dissipation in the crack-tip plastic zone was considered. By considering the propagating crack-tip plastic zone as a running heat source and constructing a reasonable heat source density distribution function, the temperature field around a steady running crack was obtained. It is shown that temperature rise is dependent on the crack growth speed and the material parameters. The maximum temperature rise reaches to >50 oC in our example calculations for a steady running crack in PMMA.

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Design of a multimesa IMPATT diode array optimise for maximum heat dissipation

IEE Proceedings G Circuits Devices and Systems ◽

10.1049/ip-g-2.1991.0037 ◽

1991 ◽

Vol 138 (2) ◽

pp. 198

Author(s):

A. Strum ◽

A. Bar-Lev

Keyword(s):

Heat Dissipation ◽

Diode Array ◽

Maximum Heat ◽

Impatt Diode

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Modeling temperature rise in multi-track reciprocating frictional sliding

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120988230 ◽

2021 ◽

pp. 135065012098823

Author(s):

Thierry A Blanchet

Keyword(s):

Temperature Rise ◽

Peclet Number ◽

Maximum Temperature ◽

Uniform Heat Flux ◽

Heat Accumulation ◽

Stroke Length ◽

Péclet Number ◽

Maximum Temperature Rise ◽

Rectangular Patch ◽

Accumulation Effect

As in various manufacturing processes, in sliding tests with scanning motions to extend the sliding distance over fresh countersurface, temperature rise during any pass is bolstered by heating during prior passes over neighboring tracks, providing a “heat accumulation effect” with persisting temperature rises contributing to an overall temperature rise of the current pass. Conduction modeling is developed for surface temperature rise as a function of numerous inputs: power and size of heat source; speed and stroke length, and track increment of scanning motion; and countersurface thermal properties. Analysis focused on mid-stroke location for passes of a square uniform heat flux sufficiently far into the rectangular patch being scanned from the first pass at its edge that steady heat accumulation effect response is adopted, focusing on maximum temperature rise experienced across the pass' track. The model is non-dimensionalized to broaden the applicability of the output of its runs. Focusing on practical “high” scanning speeds, represented non-dimensionally by Peclet number (in excess of 40), applicability is further broadened by multiplying non-dimensional maximum temperature rise by the square root of Peclet number as model output. Additionally, investigating model runs at various non-dimensional speed (Peclet number) and reciprocation period values, it appears these do not act as independent inputs, but instead with their product (non-dimensional stroke length) as a single independent input. Modified maximum temperature rise output appears to be a function of only two inputs, increasing with decreasing non-dimensional values of stroke length and scanning increment, with outputs of models runs summarized compactly in a simple chart.

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Braking performance of a novel frictional-magnetic compound disc brake for automobiles

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407018791056 ◽

2018 ◽

Vol 233 (10) ◽

pp. 2443-2454 ◽

Cited By ~ 1

Author(s):

Yan Yin ◽

Jiusheng Bao ◽

Jinge Liu ◽

Chaoxun Guo ◽

Tonggang Liu ◽

...

Keyword(s):

Magnetic Field ◽

Temperature Rise ◽

Friction Material ◽

Maximum Temperature ◽

Interface Temperature ◽

Disc Brake ◽

Braking Performance ◽

Maximum Temperature Rise ◽

Disc Brakes ◽

Braking Torque

Disc brakes have been applied in various automobiles widely and their braking performance has vitally important effects on the safe operation of automobiles. Although numerous researches have been conducted to find out the influential law and mechanism of working condition parameters like braking pressure, initial braking speed, and interface temperature on braking performance of disc brakes, the influence of magnetic field is seldom taken into consideration. In this paper, based on the novel automotive frictional-magnetic compound disc brake, the influential law of magnetic field on braking performance was investigated deeply. First, braking simulation tests of disc brakes were carried out, and then dynamic variation laws and mechanisms of braking torque and interface temperature were discussed. Furthermore, some parameters including average braking torque, trend coefficient and fluctuation coefficient of braking torque, average temperature, maximum temperature rise, and the time corresponding to the maximum temperature rise were extracted to characterize the braking performance of disc brakes. Finally, the influential law and mechanism of excitation voltage on braking performance were analyzed through braking simulation tests and surface topography analysis of friction material. It is concluded that the performance of frictional-magnetic compound disc brake is prior to common brake. Magnetic field is greatly beneficial for improving the braking performance of frictional-magnetic compound disc brake.

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Revisiting the Effect of Slag in Reducing Heat of Hydration in Concrete in Comparison to Other Supplementary Cementitious Materials

Materials ◽

10.3390/ma11101847 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1847 ◽

Cited By ~ 12

Author(s):

Hoon Moon ◽

Sivakumar Ramanathan ◽

Prannoy Suraneni ◽

Chang-Seon Shon ◽

Chang-Joon Lee ◽

...

Keyword(s):

Blast Furnace ◽

Temperature Rise ◽

Adiabatic Calorimetry ◽

Blast Furnace Slag ◽

Isothermal Calorimetry ◽

Heat Of Hydration ◽

Supplementary Cementitious Materials ◽

Maximum Temperature ◽

Mass Concrete ◽

Furnace Slag

Blast furnace slag (SL) is an amorphous calcium aluminosilicate material that exhibits both pozzolanic and latent hydraulic activities. It has been successfully used to reduce the heat of hydration in mass concrete. However, SL currently available in the market generally experiences pre-treatment to increase its reactivity to be closer to that of portland cement. Therefore, using such pre-treated SL may not be applicable for reducing the heat of hydration in mass concrete. In this work, the adiabatic and semi-adiabatic temperature rise of concretes with 20% and 40% SL (mass replacement of cement) containing calcium sulfate were investigated. Isothermal calorimetry and thermal analysis (TGA) were used to study the hydration kinetics of cement paste at 23 and 50 °C. Results were compared with those with control cement and 20% replacements of silica fume, fly ash, and metakaolin. Results obtained from adiabatic calorimetry and isothermal calorimetry testing showed that the concrete with SL had somewhat higher maximum temperature rise and heat release compared to other materials, regardless of SL replacement levels. However, there was a delay in time to reach maximum temperature with increasing SL replacement level. At 50 °C, a significant acceleration was observed for SL, which is more likely related to the pozzolanic reaction than the hydraulic reaction. Semi-adiabatic calorimetry did not show a greater temperature rise for the SL compared to other materials; the differences in results between semi-adiabatic and adiabatic calorimetry are important and should be noted. Based on these results, it is concluded that the use of blast furnace slag should be carefully considered if used for mass concrete applications.

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Thermal Analysis of AlGaN/GaN HEMTs Considering Anisotropic And Inhomogeneous Thermal Conductivity

10.21203/rs.3.rs-1064478/v1 ◽

2021 ◽

Author(s):

Yao Li ◽

Zixuan Zheng ◽

Qun Li ◽

Hongbin Pu

Keyword(s):

Thermal Conductivity ◽

Temperature Rise ◽

Power Dissipation ◽

Thermal Characteristics ◽

Maximum Temperature ◽

Base Temperature ◽

Initial Growth ◽

Boltzmann Transport ◽

Growth Interface ◽

Anisotropic Thermal Conductivity

Abstract To examine the differences of thermal characteristics introduced by material thermal conductivity, anisotropic polycrystalline diamond (PCD) and GaN are analyzed based on the accurate model of grain sizes in the directions of parallel and vertical to the interface and an approximate solution of the phonon Boltzmann transport equation. Due to the space-variant grain structures of PCD, the inhomogeneous-anisotropic local thermal conductivity, homogeneous-anisotropic thermal conductivity averaged over the whole layer and the typical values of inhomogeneous-isotropic thermal conductivity are compared with/without anisotropic GaN thermal conductivity. The results show that the considerations of inhomogeneous-anisotropic PCD thermal conductivity and anisotropic GaN thermal conductivity are necessary for the accurate prediction of temperature rise in the GaN HEMT devices, and when ignoring both, the maximum temperature rise is undervalued by over 16 K for thermal boundary resistance (TBR) of 6.5 to 60 m2K/GW at power dissipation of 10 W/mm. Then the dependences of channel temperature on several parameters are discussed and the relations of thermal resistance with power dissipation are extracted at different base temperature. Compared with GaN, SiC and Si substrates, PCD is the most effective heat spreading layer though limited by the grain size at initial growth interface.

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The Assessment of the Maximum Heat Production and Cooling Effectiveness of Three Different Drill Types (Conical vs. Cylindrical vs. Horizontal) during Implant Bed Preparation—An In Vitro Study

Applied Sciences ◽

10.3390/app11219961 ◽

2021 ◽

Vol 11 (21) ◽

pp. 9961

Author(s):

Stefan Ihde ◽

Bartosz Dalewski ◽

Łukasz Pałka

Keyword(s):

In Vitro Study ◽

Maximum Temperature ◽

Internal Cooling ◽

Type I ◽

Ir Camera ◽

Maximum Heat ◽

Disc Cutters ◽

Cooling Hole ◽

Implant Bed

The aim of this experimental study was to verify thermal diffusion differences, by measuring the maximum temperature achieved with different drill shapes. Synthetic bone blocks of type I density made from solid rigid polyurethane (PUR) foam were used to perform the drilling procedures. The experiment was conducted at three different rotation speeds: 800, 3000 and 5000 rpm. Conical drills (with and without an internal cooling hole) were compared with horizontal drills and disc drills. The temperature during drilling for implant bed preparation was estimated with the use of thermocouples and an infrared (IR) camera. The temperature during drilling with disc cutters for lateral basal implants did not exceed 33 ∘C and the temperature decreased in proportion to higher drill speed. The results indicate that the tested design is safe and will not cause bone overheating.

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