Dissipation Method Research Articles

Method and Verification of Liquid Cooling Heat Dissipation Based on Internal Heat Source of Airborne Long-Focus Aerial Camera

The traditional passive heat dissipation method has low heat dissipation efficiency, which is not suitable for the heat dissipation of the concentrated heat source inside the long-focal aerial camera, resulting in temperature level changes and temperature gradients in the optical system near the heat source, which seriously affect the imaging performance of the aerial camera. To solve this problem, an active heat dissipation method of liquid cooling cycle is proposed in this paper. To improve the solving efficiency and ensure simulation accuracy, a dynamic boundary information transfer method based on grid area weighting is proposed. The thermal simulation results show that the liquid cooling method reduces the heat source temperature by 70.12%, and the boundary temperature transfer error is 0.015%. The accuracy of thermal simulation is verified by thermal test, and the simulation error is less than 6.44%. In addition, the performance of the optical system is further analyzed, and the results show that the MTF of the optical system is increased from 0.077 to 0.194 under the proposed active liquid cooling cycle heat dissipation method.

Heat dissipation enhancement of PiGF converter with vapor chamber radiator for high-brightness laser lighting

Laser illumination is widely believed to have great development potential in high-brightness lighting and display. In order to realize high-power laser illumination, an efficient heat dissipation method was proposed for phosphor-in-glass film (PiGF) color converter. The heat dissipation of PiGF converter was enhanced by the vapor chamber radiator (VC). The VC-PiGF converter demonstrates great optical-thermal performances due to its excellent heat dissipation capability. The maximum luminous flux of VC-PiGF converter (3699.3 lm) is 38.2 % higher than that of traditional fin-PiGF converter (2677.1 lm). The VC-PiGF converter has higher laser power saturation threshold (maximum 34.51 W) than the fin-PiGF converter (maximum 29.12 W). As the laser power is 24.82 W, the operating temperature of VC-PiGF converter (128 °C) is 41.8 % lower than that of fin-PiGF (220 °C). In addition, the VC-PiGF converter exhibits stable optical performances and a low surface temperature with the continuous excitation of 15.78 W for 60 min. The VC-PiGF converter packaged in a lighting module has an excellent outdoor test result. The efficient heat dissipation method with high reliability has great application prospects in high-brightness laser lighting.

Numerical simulation for comparison of cold plate cooling and HFE-7000 immersion cooling in lithium-ion battery thermal management

In this work, fluorinated liquids can be used as a new immersion coolant for effective battery thermal management (BTM) because of their insulating and non-flammable inert characteristics. In this research, the liquid chosen for immersion cooling is HFE-7000, characterized by a boiling point of 34 °C. The analysis of bubble kinetics is employed to investigate the heat transfer mechanism in two-phase immersion cooling by examining the behavior of bubbles during the boiling process. The square ternary Li-ion batteries are subjected under loads of 2C and 3C cooled by immersion cooling and a mini-channel cold plate as a comparison. It turns out that immersion liquid cooling modules offer superior thermal performance. Under constant current (CC), the peak temperature is reduced by 4.89 °C and 9.31 °C compared with the mini-channel cold plate cooling (CPC). Under dynamic load conditions, the maximum temperature rise of the battery is reduced by 29.89 % and 43.89 % compared to CPC. As a passive heat dissipation method, two-phase immersion cooling reduces the design requirements for active control. Also, it delivers an efficient battery thermal management system (BTMS) designed for upcoming electric vehicles (EVs).

Effect of localized dry-out on startup and steady-state operation characteristics of ethanol-based oscillating heat pipes

It’s a significant challenge to choose a suitable heat dissipation method in different electronics assembly environments requiring different heat transfer distances. Oscillating heat pipes are promising heat exchangers, but localized dry-out during operation leads to an unstable heat transfer and limits further application of oscillating heat pipes. To extend the applicability of oscillating heat pipes, it is essential to reveal the localized dry-out characteristics under various heat transfer distances. In this study, the impact of localized dry-out on the multi-stage operating characteristics of ethanol-oscillating heat pipes with various heat transfer distances was investigated through partial visualization experiments. The anti-dry-out capacity of ethanol-oscillating heat pipes was quantitatively evaluated and compared with that of water-oscillating heat pipes. The experimental results revealed that the dry-out performance was closely related to the flow motion of the operating fluid. The stagnation of the operating fluid was the primary cause of localized dry-out. Localized dry-out deteriorated the startup and heat transfer performances of oscillating heat pipes. The anti-dry-out capacity first improved and then diminished as the heat transfer distance increased. The results also revealed that ethanol exhibited superior dry-out performance compared to water, especially at long heat transfer distances. Besides, an empirical correlation equation was fitted to evaluate the anti-dry-out capacity of oscillating heat pipes under different heat transfer distances based on the experimental results. The empirical correlation equation about the Ku number could be a reasonable predictor of the anti-dry-out capacity of oscillating heat pipes. The predicted results were in good agreement with the experimental results, with 86 % of the data deviating within ±20 % and an average standard deviation of 19.72 %. This research closed the gap in the prediction for the anti-dry-out capacity and provided a valuable reference to broaden the applicability of oscillating heat pipes.

Energy dissipation methods and protection device synergy strategies for offshore wind power receiving end surplus power

Abstract Firstly, a theoretical analysis of the fault ride-through scheme is carried out based on the land-side AC faults in the offshore wind power delivery system. According to the topological structure of the DC energy consumption device, the working mode and switching of the DC energy consumption device are analyzed and studied. Secondly, the DC protection action of offshore wind power flexible and direct transmission systems was studied, and the switching strategy of energy-consuming devices was determined. Then the impact of the switching of the energy-consuming device on the DC protection function was studied, focusing on the synergy between the DC overvoltage protection and the switching judgment voltage of the energy-consuming device. Finally, based on a typical offshore wind power flexing project, a system model is built in PSCAD/EMTDC to verify the effectiveness of the proposed synergy strategy.

A review of physical heat dissipation methods for 3D integrated technology

Three-dimensional integrated circuits have higher integration than two-dimensional integrated circuits, and can obtain higher performance and lower power consumption in a certain space. In order to fulfill higher efficiency, thermal management becomes particularly important in 3D integration technology. However, the traditional heat dissipation method cannot satisfy the heat dissipation needs of three-dimensional integrated circuits, which require better heat dissipation methods to be developed. This paper introduces the realization of three-dimensional integrated circuit using silicon via (TSV) technology, which allows the chip to be vertically stacked to transmit information. This paper summarizes the research methods and findings of three-dimensional integrated circuit heat dissipation in recent years, including thermal through silicon via (TTSV) and microchannel cooling. It also emphasizes the advantages and disadvantages of both mehods, and the challenges faced in current research via an overview. The future research trend for both heat dissipation methods mainly consists of combining special algorithms to achieve thermal-electrical codesign and thermal management of three-dimensional integrated circuits.

Effect of sawtooth wave distribution plenum with linearly increasing amplitude on the performance of battery thermal management system

Battery heat generation that occurs during battery charging and discharging can lead to excessive and non-uniform battery temperature in the battery pack. As a result, the battery is more vulnerable to rapid degradation and short cycle life. Effective heat dissipation methods therefore become crucial. In the present study, sawtooth waves with linearly increasing wave amplitude and an inlet notch on the distribution plenum (DP) have been introduced in a typical Z-type battery thermal management system (BTMS) to maximise the cooling effectiveness of the System. Numerical analysis is carried out to investigate the effect of various geometric parameters such as saw tooth wave position, saw tooth wave amplitude, saw tooth wave base width, inlet notch width, and inlet notch height on the performance of BTMS. Velocity contours, streamlines, temperature contours, and maximum battery temperature plots are used to discuss the effects of various factors on the operation of a BTMS. Compared with the typical Z-type BTMS, the modified enclosure design reduced the maximum average battery temperature ( T max ) and maximum temperature differential within the battery pack ( Δ T max ) by 5.11 and 9.01 K respectively, which are 1.56% and 94.90% less than the typical Z-type BTMS respectively.

On the study of a body force model for a jetting type breakwater

The introduction of jetting-type floating breakwaters can significantly enhance the performance of large floating marine structures. Especially, this novel technology may effectively handle traditional breakwaters' bottleneck, namely, weak wave dissipation performance under large period waves. In this paper, a new method is established using body force model, in conjunction with a computational fluid dynamics solver and dynamic overlapping mesh technology, to simulate jetting-type floating breakwaters. The mathematical model is elucidated in the context of fluid mechanics, propellers body force model, and floating breakwaters’ geometric aspects. The method is proved to be compact and flexible in terms of implementation, offering advantages for the simulation of floating breakwaters employing hydraulic systems. Moreover, the new method can resolve low efficiency during computation, normally caused by fine local flows when simulating long-range jetting-type floating breakwaters: By controlling parameters precisely, it simulates accelerating local flows, high-speed water-jets, and it offers efficient visualization of the water-jets and their effects on floating breakwaters. Results show that the novel jetting-type floating breakwater significantly enhances wave dissipation. A comparison is performed between the novel breakwater against the typical example of square box floating breakwater with same dimensions and under wave incidence, thus the accuracy of the method was verified likewise. This research provides a new numerical method for jetting technologies applied to floating breakwaters and porous structures, also offering valuable insights for new types of wave dissipation methods.

Analysis of the Dimensional and Shape Accuracy and Repeatability of Models Produced in the Process of Additive Extrusion of Thermoplastic Polymers Using Fused Filament Fabrication Technology

To achieve high precision and repeatability of prototyped models, work is carried out to improve existing solutions and thus expand the areas of application of 3D printers. Ways to increase the efficiency of 3D printing are being sought. The subject of the work concerns the analysis of dimensional and shape accuracy and repeatability of samples produced by a technology based on layered extrusion of thermoplastic polymers using FFF—fused filament fabrication technology. The key parameter for assessing the quality of parts is the property most expected by 3D printer users regarding the accuracy of dimensions of manufactured prototypes. As part of the research, conclusions were drawn regarding the precision of the samples as original patterns. The dimensional accuracy in the x, y, and z axes of the 3D printer was determined in terms of the design of the 3D printer’s actuator system. Three-dimensional maps of deviations of the pattern surface were used in relation to the nominal 3D CAD model to test the accuracy. The analytical results obtained during the research work, together with the graphs of the normal distribution probability function, indicate a high repeatability for each of the axes, and the highest repeatability was for the z-axis. The dimensions in the remaining axes were within the assumed tolerance of 0.1 mm, except for the two extreme dimensions, which were caused by a different method of heat dissipation, proving the influence of the arrangement of samples on the working platform.

Heat dissipation and temperature control method for quantum cascade lasers in external cavity spectral beam combining systems

The thermal effects of quantum cascade lasers (QCLs) can cause wavelength locking instability and reduce output power in external cavity spectral beam combining (EC-SBC) systems. We propose a micro-channel structure (MCH) for heat dissipation and temperature control that rapidly stabilizes the QCL at 20.159°C, showing a linear relationship with the controlled temperature. Experimental comparisons demonstrate that MCH enhances the heat transfer rate within the structure, reducing the time required to stabilize and control QCL temperature. The output power and locked wavelength remain stable in the EC-SBC system under high currents. This study provides technical support for heat dissipation QCL arrays.

Design and application of a hemodialysis machine suitable for transporting patients

Blood purification is one of the commonly used techniques for the rescue of critically ill patients, which is used for acute and chronic kidney injury caused by various causes and renal replacement therapy (RRT) for a variety of critical diseases. Its main working principle is to drain the human blood into a variety of dialyzers through the artificial tube, exchange substances through a variety of ways, and remove harmful substances and some metabolites from patients' body. Then the purified blood is transfused back to the body, so as to maintain the patient's internal environment relatively stable. At present, there are different models of hemodialysis machines in clinical practice, but they are bulky and unable to move, and the method of heat dissipation is single, which cannot meet the needs of hemodialysis treatment in transport patients. Therefore, the medical staff of the Second Affiliated Hospital of Zunyi Medical University designed and developed a hemodialysis machine, which is suitable for patients who demand hemodialysis treatment during transport, and obtained the National Invention Patent of China (ZL 2020 1 0864737.3). The hemodialysis machine comprises a main body of the hemodialysis machine and a mobile vehicle. The main body of the hemodialysis machine is placed in the bottom of the mobile vehicle, and a protective cylinder with fixed airbags is designed around the main body of the hemodialysis machine. The fixed airbag is connected to the air storage tank through the pipeline, the air storage tank is connected to the Venturi tube through the control valve, and the throat of the Venturi tube is connected to the disinfection tank and cooling water tank. The outlet end of the Venturi tube is connected with the cooling pipe inside the main part of the hemodialysis machine and the sprinkler head placed on the top of the main body. By adding a mobile vehicle and designing an airbag and protective cylinder, the hemodialysis machine can be applied to the hemodialysis treatment during the transportation of patients. By designing the heat dissipation pipe, the main body of the hemodialysis machine can be cooled, the temperature of the hemodialysis machine can be reduced, and the hemodialysis machine can still work when the fan is damaged. By designing the sprinkler head, it is convenient to automatically disinfect the main screen and control keys of the hemodialysis machine, reduce the risk of cross infection of medical staff in the operation, and increase the safety and practicability of the hemodialysis machine. The hemodialysis machine is convenient, safe and efficient, which can be widely used in the hemodialysis treatment during transported patient, and is worthy of clinical promotion.

Thermal hydraulic performance of tree-like microchannel heat sink with high branching level based on the improved Murray's law

Based on the traditional Murray's law, the tree-like microchannel heat sinks (TLMHSs) cannot distribute the branching microchannels in given heat source region, so they cannot fully match exactly with the chips. This causes that their heat dissipation capacity is not very outstanding among various heat dissipation methods, and cannot be employed as a cooling method for chips with high heat flux. This paper improves the Murray's law and enables high-level branching microchannels to cover the whole region of heat source. Based on the modified Murray's law, the TLMHSs with evenly-distributed high-level microchannels (TLMHS-Ms) are proposed and their flow and heat transfer characteristics are analyzed numerically using the commercial software Fluent. The results indicate that the improved Murray's law can avoid obvious non-branching region found in the conventional TLMHSs (TLMHS-Cs). Compared with the TLMHS-Cs, the TLMHS-Ms possess the lower maximal temperature, temperature difference and thermal resistance. Depending on the aforementioned superior heat dissipation properties, the TLMHS-Ms can afford the higher heat flow under the same conditions. It is also found that the higher branching levels in the TLMHSs tend to reduce the maximal temperature, temperature difference, thermal resistance, Nusselt number and pressure drop, but the higher coefficient of performance. Among all TLMHSs, the TLMHS-Ms with kmax=6 can afford the largest heat flux of 264 W/cm2. This work can provide a novel TLMHS with evenly-distributed high-level microchannels for cooling the chips with high heat flux.

Experimental and numerical analysis of heat sink using various patterns of cylindrical pin-fins

The increasing heat generated by electronic devices requires effective dissipation methods. This research proposes a unique pin-fin (PF) design inspired by cylindrical pin-fins, including three patterns: cross-pin-fins (CPFs), parallel-pin-fins (PPFs) and double-cross-pin-fins (DCPFs). The study examines the hydrothermal performance of these designs within Reynolds numbers of 4500 to 18,000 and heat fluxes of 445 W/m² to 2281 W/m². The PF design aims to maximise performance by increasing surface area and airflow turbulence. Experimental data confirmed the computational results for the PF and CPF heat sinks, exhibiting significant agreement. A numerical study evaluated the hydrothermal performance, revealing that DCPFs deliver a superior performance. As the diameter expands, the Nusselt number (Nu) rises significantly across each design, with increases of 100 %, 162 % and 328 % for the PPFs, CPFs and DCPFs, respectively. Each configuration achieved a Heat Transfer Performance Factor (HTPF) exceeding 1, indicating improved heat transfer efficiency over the friction factor. The heat sink comprising the DCPFs achieved a high HTPF of approximately 2, irrespective of the Reynolds numbers and heat fluxes, demonstrating its effectiveness in heat dissipation compared to other designs.

P‐121: Research on heat dissipation of high power consumption LED display

The use of high‐power circuit devices puts forward high heat dissipation requirements for LED display. Several heat dissipation methods are studied in this paper to provide a reasonable idea of high power consumption LED display.

Quantifying Eucalyptus Transpiration Using the Dissipation Thermal Technique in Porto Seguro, Bahia

Granier’s sap flow method proved to be an important tool for estimating transpiration in woody plants. The present work aimed to estimate the transpiration of two clones (VCC0865 and CO1407) of a hybrid of the eucalyptus species Eucalyptus grandis × Eucalyptus urophylla, in order to understand the efficiency and patterns of water use in the forest ecosystem. The experiment was carried out on a eucalyptus farm in the municipality of Porto Seguro, located in the extreme south of Bahia. The spacing between trees was 3.60 m × 2.50 m. Sap flow measurements were performed daily, between February and December 2022, using 10 sensors installed in tree trunks, according to Granier’s thermal dissipation method. Data were recorded in the datalogger model CR10X system. For the systematization and analysis of the data, the R programming language was used. The results obtained indicated that the beginning of the transpiration period of the clones occurred around 07:00. On rainy days, less transpiration was observed in both clones. There were no significant changes in sap flow between dry and rainy seasons. It was also found for clone VCC0865 a transpiration rate of 43% higher in the daily average compared to clone CO1407. The present work is an important tool to contribute with information about transpiration in eucalyptus cultivation in the extreme south of Bahia, since there are few studies on the subject and given the importance of the activity in the region.

Multi-objective optimization analysis of air-cooled heat dissipation coupled with thermoelectric cooling of battery pack based on orthogonal design

As the energy supply core of electric vehicles (EVs), the battery's performance is closely related to its temperature. Therefore, the battery thermal management system (BTMS) plays a crucial role in ensuring the vehicle's driving safety and power performance. This paper proposes the air cooling as the primary heat dissipation method, combined with a semiconductor refrigeration sheet (SRS) to improve heat transfer and reduce local high temperature. Firstly, determine the optimum air volume with the U-type air-cooled structure. Additionally, orthogonal analysis is used to investigate the inlet and outlet locations, the front deflector position and length of the shunt chamber, and the rear deflector position on the air-cooling effect. Then, through multi-objective optimization, the optimal air-cooled structure is selected based on the air supply pressure drop. The chosen structure is the same-side dual-exit ventilation with a front deflector located 150 mm from the near-wind end wall and a length of 30 mm, and a rear deflector located 100 mm from the far-wind end wall. Finally, SRS coupled air cooling is used to dissipate the heat. Four SRSs are used to analyze the effect of mounting position and different currents on the battery pack. The findings suggest that the optimal placement for SRSs is parallel to the lower end of the battery module at the far-wind end. When SRSs pass a current of up to 0.4A at 37 ℃, the entire battery module can complete 7200 s discharge with 0.5C. This leads to a decrease in the maximum temperature (Tmax) to 46.09 ℃ and a drop in the temperature uniformity index (δT) to 1.36.

Convective boiling heat transfer enhancement via femtosecond laser textured inclined microfeatures

Designing efficient cooling devices is crucial in a multitude of applications. Although cooling technologies have existed for decades, there is a lack of efficient heat dissipation methods, especially for space applications where thermal management devices must dissipate heat in reduced gravity and where convective boiling heat transfer is frequently employed. In this framework, we evaluate the change in bubble production for different types of surface textures produced on 200 µm thick 316L SS foils using a femtosecond laser. The investigated textures include microscale grooves and conical holes with tilted (= 45°) geometry. In addition, we also evaluate the effect of laser-induced periodic surface structures (LIPSS), which are sub-micron scale features fabricated by fs laser processing. The fluid used is PP1, a replacement of 3M™ FC-72 in heat transfer applications.

Port-Hamiltonian modeling and jumping trajectory tracking control for a bio-inspired quadruped robot

Applying jumping locomotion into autonomous mobile robot is an effective way for improving abilities to overcome barriers and pass through complex terrains. In this paper, based on the designed structural framework for bio-inspired quadruped jumping robot, dynamic model is established by utilizing port-Hamiltonian with dissipation (pHd) method, and a passivity-based control strategy for the robot joints trajectory tracking is presented. First, morphology and biomimetics knowledges of frogs (a kind of animals with excellent jumping skill) motivate us to complete a bio-inspired jumping robot framework based on frog’s motion mechanism and body structure with torsional springs as energy storage device. Then, combining system passivity and dissipation, port-Hamiltonian method is utilized to build a dynamic model for expressing the relationship of energy and force in the designed robot. Jumping process analysis of different stages is also designed for ensuring the robot to complete taking-off and landing stages successfully. Next, with the definition of extending feasible robotic joint trajectory by La Salle invariant set principle, interconnection and damping assignment passivity-based control (IDA-PBC) method is exerted to obtain a trajectory controller for realizing smoothly and stably trajectory tracking in joint space. At last, simulation results show the reasonableness of the designed framework. By comparing our method with state-feedback and sliding mode control, effectiveness of the dynamic model and trajectory controller is also verified.

Comparison of collision dynamics of soccer balls with energy dissipation method

This study aimed to understand the collision characteristics of different soccer balls by determining energy dissipation (ED) during collisions. Soccer balls from five different brands were kicked towards a framed tempered glass. The kicks were performed with the balls inflated under three inner pressure conditions. The motion of each ball was recorded using two high-speed cameras at 6000 Hz. The contact surface area (CSA), ball indentation amount (IA), reaction forces (RF) and energetic coefficient of restitution (CoR) during contact were calculated via image processing methods. A new methodological approach was developed to determine the ED during the collision (EDDC). The accuracy of the estimated RF was validated using force plate data, and the CSA values validated the calculated IA. The EDDC were then reduced to a single value to compare with the CoR values obtained using the traditional formula. Differences between CoR and EDDC were statistically tested. One-way ANOVA tests were performed separately to compare the effect of the ball brand on the IA and EDDC for each inner pressure condition. The CoR and EDDC showed no significant difference, proving that the developed method is a valid measure of ED. At 1.0 bar inner pressure, IA and EDDC showed significant differences according to the brands. EDDC, depending on the ball quality, decreased at higher inner pressure values regardless of the brand. Consequently, the present study exhibited that ball quality becomes a critical factor in collision dynamics at high inner pressure values, considering that ball inner pressure may vary between 0.6 and 1.0 bar in official soccer matches.

Research Status of Heat Dissipation Technology for Electric Vehicle Drive Motors

Background:: The application of electric vehicles in daily life is becoming increasingly widespread. However, the heat dissipation issues of the electric motors directly impact electric vehicles' stability and safety. Thus, research on the heat dissipation of the electric motor is conducive to improving the reliability of the drive motor and ensuring the overall stability and safety of electric vehicles; there is a growing emphasis on the development trends of heat dissipation technologies for electric vehicle drive motors. Objective:: In order to meet the increasing requirements of electric vehicles for stability and safety and to solve the problems of low heat dissipation efficiency of electric vehicle drive motors, the size of heat dissipation devices, and the short life span caused by the high temperature of drive motors, the heat dissipation of drive motors is optimized and the heat dissipation structure is improved. Methods:: Based on the structural characteristics of heat dissipation of electric vehicle drive motors, various representative patents related to the current heat dissipation technology of electric vehicle drive motors are summarized. Results:: By summarizing a large number of patents on electric vehicle drive motor heat dissipation technology, it is concluded that the current research on electric vehicle drive motor heat dissipation mainly focuses on liquid heat dissipation or gas heat dissipation and that the main reason for the heat dissipation problem of electric vehicle drive motors is the low heat dissipation efficiency due to over-reliance on a single heat dissipation method, and the reliability is poor due to failure to reasonably control heat dissipation according to the need for heat dissipation. This paper proposes a new idea of heat dissipation for electric vehicle drive motors, which effectively combines liquid heat dissipation and gas heat dissipation. Moreover, the heat dissipation efficiency will be significantly higher than the existing heat dissipation scheme, and the proposed heat dissipation concept of "ondemand distribution" will effectively improve the utilization rate of the heat dissipation medium and reduce the heat dissipation cost and the reasonable heat dissipation structure will reduce the volume of the heat dissipation device. The reasonable heat dissipation structure will also reduce the volume of the heat dissipation device. In addition, the future development of heat dissipation technology for electric vehicle drive motors is also discussed. Conclusion:: The heat dissipation scheme proposed in this paper will effectively improve the heat dissipation problem of electric vehicle drive motors. Compared with the existing heat dissipation methods, the heat dissipation efficiency of the heat dissipation scheme proposed in this paper will be improved by more than 8.5%, and the service life of the drive motor will be extended by more than 5.1%, while the size of the electric vehicle drive motor will be reduced by 6%. More related patents will be invented in the future.