scholarly journals Heat Transfer and Its Innovative Applications

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 4
Author(s):  
Ping-Hei Chen ◽  
Hyung Cho
Keyword(s):  
Heat Transfer ◽  
Artificial Intelligence ◽  
High Speed ◽  
Heat Dissipation ◽  
Outer Space ◽  
Electronic Devices ◽  
Daily Lives ◽  
Autonomous Cars

Innovative and high-end techniques have been recently developed in academic institutes and are gradually being employed in our daily lives for improving living quality, namely, artificial intelligence (AI) technology, autonomous cars, hyper-loop for high-speed transportation, miniaturization of electronic devices, heat dissipation from cooling films to outer space, and so on [...]

Convective Cooling of Compact Electronic Devices via Liquid Metals with Low Melting Points

2021 ◽  
Author(s):  
Guilin Liu ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Melting Point ◽  
Liquid Metal ◽  
High Performance ◽  
Flow Resistance ◽  
Heat Dissipation ◽  
Liquid Metals ◽  
Electronic Devices ◽  
Convective Cooling ◽  
Heat Exchanger Design

Abstract The increasingly high power density of today's electronic devices requires the cooling techniques to produce highly effective heat dissipation performance with as little sacrifice as possible to the system compactness. Among the currently available thermal management schemes, the convective liquid metal cooling provides considerably high performance due to their unique thermal properties. This paper firstly reviews the studies on convective cooling using low-melting-point metals published in the past few decades. A group of equations for the thermophysical properties of In-Ga-Sn eutectic alloy is then documented by rigorous literature examination, following by a section of correlations for the heat transfer and flow resistance calculation to partially facilitate the designing work at the current stage. The urgent need to investigate the heat transfer and flow resistance of forced convection of low-melting-point metals in small/mini-channels, typical in compact electronic devices, is carefully argued. Some special aspects pertaining to the practical application of this cooling technique, including the entrance effect, mixed convection, and compact liquid metal heat exchanger design, are also discussed. Finally, future challenges and prospects are outlined.

Experiments and Modeling of a Liquid Droplet Transported by a Gas Stream Impinging on a Heated Surface: Evaporative Regime

2009 ◽  
Author(s):  
Ryan P. Anderson ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Single Phase ◽  
Heat Dissipation ◽  
Liquid Droplet ◽  
Heated Surface ◽  
Thin Liquid Film ◽  
Spray Cooling ◽  
High Speed Photography ◽  
Transfer Coefficients

Understanding the transport mechanisms involved in a single droplet impinging on a heated surface is imperative to the complete understanding of droplet and spray cooling. Evidence in the literature suggests that gas assisted sprays and mist flows are more efficient than sprays consisting only of liquid droplets. There has been few if any fundamental studies on gas-assisted droplets or spray cooling, in which a carrier gas or vapor stream propels the droplet to the target surface. The current work extends previous studies of a droplet impinging on a heated surface conducted by the same group from the single phase regime into the evaporative regime. For both regimes, understanding the transport physics due to the heat transfer from the heated surface to the droplet and then by convection and evaporation to the airflow is of fundamental importance. High-speed photography was used to capture the spreading process and yielded results that correlated well with previously published isothermal and single-phase results. The heat transfer was measured with a fitting approach by which the instantaneous temperature profile was matched to an analytic solution to determine the instantaneous value of the centerline heat transfer coefficient. A very large increase in the heat dissipation was observed when compared to previously published single-phase results. Heat transfer was optimized at Reynolds numbers that produced an optimally thin liquid film and high heat and mass transfer coefficients on the surface of the film.

Improved Heat Dissipation Capability on Electronic Motor Control Devices

2005 ◽  
Author(s):  
Wei Tong
Keyword(s):  
Heat Transfer ◽  
Motor Control ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
Heat Sinks ◽  
Vortex Generators ◽  
Maximum Temperature ◽  
Complex Heat Transfer ◽  
Pin Fins ◽  
Control Devices

Heat sinks have been widely used in electronic industry to maintain the operation temperatures of electronic devices lower than their allowable values and thus are often critical to the device performance and life. However, it is difficult to design heat sinks to satisfy all design specifications optimally under complex heat transfer phenomena. The present work discloses a new design of heat sinks to improve heat dissipation capability for electric motor control devices. The heat sink contains a plurality of raindrop-shaped pin fins, acting as vortex generators to increase the rate of heat transfer and in turn, to increase the cooling efficiency of the heat sinks. Numerical results have shown that with the new designed heat sinks, the maximum temperature can reduce about 30% over the conventional heat sinks.

scholarly journals Numerical simulation of heat dissipation of surface mounted permanent magnet synchronous hub motor

2021 ◽  
Vol 25 (6 Part A) ◽  
pp. 4059-4066
Author(s):  
Shuai Leng ◽  
Liqiang Jin
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Permanent Magnet ◽  
High Speed ◽  
Heat Dissipation ◽  
Heat Radiation ◽  
Insulation Material ◽  
Safety Hazard ◽  
Insulation Aging ◽  
Potential Safety

Due to the insulation aging, demagnetization and other problems of the permanent magnet and insulating material in the permanent magnet synchronous hub motor under high temperature, the numerical simulation of the heat dissipation of surface mounted permanent magnet synchronous hub motor is proposed. According to the heat transfer of hub motor, the effect degree of heat conduction, heat convection and heat radiation is obtained, the heat transfer coefficient of each part is calculated, and the influence of motor insulation material on temperature rise is analyzed. The experimental results show that the heat dissipation of hub motor under natural cooling condition is poor, and the internal oil cooling method can effectively improve the heat dissipation of hub motor and reduce the temperature difference. When operating at high speed, this reduces the potential safety hazard.

Experimental Study of Helix-Finned Surface for Nucleate Pool Boiling

2016 ◽  
Author(s):  
Kailun Chen ◽  
Changqi Yan ◽  
Cable Kurwitz ◽  
Kun Cheng ◽  
Haozhi Bian
Keyword(s):  
Heat Transfer ◽  
3D Printing ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Heat Dissipation ◽  
Nucleate Boiling ◽  
Experimental Investigations ◽  
Printing Technique ◽  
Finned Surface ◽  
3D Printing Technique

This research presents results from experimental investigations on helix-finned surface fabricated by a 3D printing technique to evaluate boiling heat transfer performance. The experiments were conducted in saturated water at atmospheric pressure. To the author’s knowledge, this is the first attempt that helical pin fins are employed in thermal management. The boiling curve of the enhanced surface was characterized by a much lower wall superheat at the same heat flux compared with plain surfaces. High-speed visualization was used to display instantaneous bubble behaviors such as the bubble departure frequency, which was obtained from analyzed images. It was observed that the helix-finned surface had higher bubble departure frequencies compared to plain surfaces and an earlier onset of nucleate boiling was noticed. It is concluded that the surface roughness and micron level cavities produced by the 3D printing technique on the helix surface are key factors to enhance boiling heat transfer. With the experience gained, dimension optimization of helical structure should be studied further to meet the needs of increased heat dissipation rate.

scholarly journals Influence of Vacuum Level on Heat Transfer Characteristics of Maglev Levitation Electromagnet Module

2020 ◽  
Vol 10 (3) ◽  
pp. 1106 ◽  
Author(s):  
Yiqian Mao ◽  
Mingzhi Yang ◽  
Tiantian Wang ◽  
Fan Wu ◽  
Bosen Qian
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Speed ◽  
Heat Dissipation ◽  
Aerodynamic Drag ◽  
Convection Heat Transfer ◽  
Total Heat ◽  
Heating Process ◽  
Convection Heat ◽  
Vacuum Level

The vacuum tube transportation (VTT) system has been a promising direction of future transportation. Within this system, a high-speed maglev travels in a low-vacuum environment to reduce aerodynamic drag. However, the heat dissipation of on-board heating devices will be compromised under low-vacuum conditions, and the device performance may thus be lowered. This study investigates the low-vacuum conjugate heat transfer characteristic of a levitation electromagnet module of a maglev using an experimentally verified numerical method. During the heating process, the surface temperature distribution of the levitation electromagnet, and the temperature and velocity characteristics of the flow field are examined. It is found that, as the vacuum level increases from 1.0 atm to 0.1 atm, the total heat dissipating from the levitation electromagnet module is decreased by 49% at 60 min, the contribution of convection heat flux over the total heat flux is decreased from 49% to 17%, and the convection heat transfer coefficient of the levitation electromagnet is decreased by 89%. This study can provide an efficient numerical model for low-vacuum heat transfer study on a VTT system as well as help the evaluation and optimization of low-vacuum maglev thermal management systems.

scholarly journals Temperature Field and Thermal Stress Analyses of High-Speed Train Brake Disc Under Pad Variations

2015 ◽  
Vol 9 (1) ◽  
pp. 371-378 ◽  
Author(s):  
Chen Jiguang ◽  
Gao Fei
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Thermal Stress ◽  
High Speed ◽  
Heat Dissipation ◽  
Surface Radiation ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Frictional Heat ◽  
Brake Disc

Transient heat transfer analysis of disc brake has been performed to find out an ideal shape of pad geometry. The analysis has taken frictional heat between brake disc and pads as heat flux onto the friction surface, the disc and the pad's temperature fields then were explored involving thermal conduction, forced convection and surface radiation effects. The disc thermal expansion stress was then acquired by quasi-static analysis using its temperature of aforesaid heat transfer analysis. Five prototypes of pad designs with geometry and volume variations were implemented for analytical comparison. Both pads and disc are required to have lower and uniform temperature field and thermal stress. The results uncover that heat conduction is domination in heat dissipation progress during braking, and big volume pad is cooler. Pad volume has more impact to heat transfer procedure and temperature gradient than pad geometry variation does. The design has 10 triangle pads is considered to be an ideal candidate. Its maximum disc temperature and thermal stress are the least among the five designs.

scholarly journals Thermal Analysis of Microchannels Heat Sink using Super-hydrophobic Surface

2021 ◽  
Vol 9 (9) ◽  
pp. 654-657
Author(s):  
Shubham Jawade
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Rectangular Cross Section ◽  
Electronic Devices ◽  
Hydrophobic Surface ◽  
Hydraulic Diameter ◽  
Microchannel Heat Sink ◽  
Transfer Rates ◽  
Compact Size

Abstract: Electronics devices are the major part of modern technology and with the rapid growth of miniaturizations of electronic devices, the heat dissipation from these devices have been the objective for researchers. This heat dissipation has to done effectively otherwise this will affect the life of device and will result decrement in efficiency. Increasing the heat transfer rates from electronic devices has long been a quest. Microchannel heat sink is one of the best option for removing heat from the electronics devices due to its compact size which provides high surface area to volume ratio that enables higher heat transfer rates. Microchannels are the flow passages having hydraulic diameter ranges from 10 micrometer (µm) to 200µm. Microchannel heat sink enhances the feasibility of electronics device. Microchannels with hydrophobic surface are a promising candidate for cooling of electronics devices, as hydrophobic surface can be used to create friction free regions with a channel which effectively reduce pumping power, flow pressure drop and frictional factor compared to Microchannel without Hydrophobic surface. This paper deals with the detailed behavior of Microchannel with hydrophobic surface. In this work, rectangular cross section with 0.8 mm (800 micron) hydraulic diameter super hydrophobic microchannel is used. Keywords: Microchannel, Hydrophobic surface, Heat transfer rate, Frictional factor.

An Investigation of Heat Dissipation in High Speed Machining

2009 ◽  
Vol 69-70 ◽  
pp. 480-484 ◽  
Author(s):  
Yan Ming Quan ◽  
Joseph A. Arsecularatne ◽  
Liang Chi Zhang
Keyword(s):  
Heat Transfer ◽  
Surface Integrity ◽  
Temperature Rise ◽  
Material Removal ◽  
High Speed ◽  
Heat Dissipation ◽  
High Speed Machining ◽  
Heat Transfer Medium ◽  
Quantitative Understanding ◽  
Bar Turning

High speed machining (HSM) is finding wider applications due to its economic advantages, such as faster material removal rates, and its technological merits, such as improved surface finish. Nevertheless, the application of HSM also brings about some undesirable results. For example, the tool life and surface integrity of a machined component are greatly affected by the large amount of heat generated, but heat dissipation during an HSM has not been well understood. This paper aims to achieve a quantitative understanding of the heat dissipation in HSM using a bar turning configuration. Based on the calorimetric method and utilizing water as the heat transfer medium, the temperature rise in water was measured to determine the fractions of heat dissipated into the chips, the tool and the workpiece during machining. The obtained results show that the chips take the largest portion of the heat generated and this fraction increases with the increase in feed.

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