Microchannel Technology Research Articles

Research Progress of Microchannel Liquid Cooling Technology in the Application of Thermal Management of Prismatic Lithium Batteries (Withdrawn)

Lithium-ion batteries have significant advantages such as high energy density, long cycle life and low self-discharge rate. Therefore, they are ideal for energy storage in electric vehicles. However, lithium-ion batteries are very sensitive to temperature, which affects the battery's cycle life, efficiency, reliability and safety. During the charging and discharging process, a large amount of heat is generated inside the battery due to the electrochemical reaction and resistance, causing the battery temperature to rise. When the temperature gets too high, thermal runaway, electrolyte fire and explosions may occur. As battery energy density increases, the demand for efficient thermal management continues to increase, and a compact and efficient battery thermal management system is essential. This paper introduces the development status of different thermal management technologies, reviews the application of microchannel liquid-cooling technology in the thermal management of prismatic lithium batteries, discusses the current research direction and status of microchannel technology, and finally looks forward to the future research and development direction of microchannel technology.

Synthesis of boron-based High-Energy composite microspheres via the Co-Flow microchannel method

Boron-based metastable intermolecular composites (MIC), renowned for their swift energy release and elevated thermal output, exhibit significant promise for utilization in domains such as gunpowder, propellants, and powdered fuel ramjet fuels. The work successfully accomplished the safe and efficient preparation of B/Bi2O3 microunits by utilizing co-flow microchannel technology. The choice of the optimal binder, F2603, for this system was determined by simulation analysis. The practicality of the microchannel platform was then verified using Fluent. SEM analysis demonstrated that an amount of 10 % F2603 resulted in the formation of spherical particles. In terms of physical properties, boron treated with 10 % F2603 exhibits a reduction in its angle of repose from 35° of the raw material to 15°, along with a significant enhancement in hydrophobicity. Furthermore, the MICs lower the reaction temperature of raw boron from 840℃ to 770℃. In the constant volume combustion test, the MIC output pressure increased by 33.3 %. In the constant pressure combustion test, the MIC ignition delay time was reduced from 0.7262 s to 0.5566 s. The structural characteristics of the system decrease the distance for mass and heat transmission across components, resulting in improved overall performance. The study unequivocally demonstrates the efficacy of co-flow microchannel technology in swiftly, effectively, and securely producing energetic molecules. It establishes a solid foundation for future industrial manufacturing.

Sea Cucumber-Inspired Microneedle Nerve Guidance Conduit for Synergistically Inhibiting Muscle Atrophy and Promoting Nerve Regeneration.

Muscle atrophy resulting from peripheral nerve injury (PNI) poses a threat to a patient's mobility and sensitivity. However, an effective method to inhibit muscle atrophy following PNI remains elusive. Drawing inspiration from the sea cucumber, we have integrated microneedles (MNs) and microchannel technology into nerve guidance conduits (NGCs) to develop bionic microneedle NGCs (MNGCs) that emulate the structure and piezoelectric function of sea cucumbers. Morphologically, MNGCs feature an outer surface with outward-pointing needle tips capable of applying electrical stimulation to denervated muscles. Simultaneously, the interior contains microchannels designed to guide the migration of Schwann cells (SCs). Physiologically, the incorporation of conductive reduced graphene oxide and piezoelectric zinc oxide nanoparticles into the polycaprolactone scaffold enhances conductivity and piezoelectric properties, facilitating SCs' migration, myelin regeneration, axon growth, and the restoration of neuromuscular function. These combined effects ultimately lead to the inhibition of muscle atrophy and the restoration of nerve function. Consequently, the concept of the synergistic effect of inhibiting muscle atrophy and promoting nerve regeneration has the capacity to transform the traditional approach to PNI repair and find broad applications in PNI repair.

An overview of conjugate heat transfer augmentation methods for thermal management and recent advancements in microchannel heat sink overall performance

Recent technological advancement creates high-dense circuits development which creates colossal cooling demand requirements. In the future, advanced technology and scientific applications need to balance heat fluxes beyond limitation that catalyse the research opportunities further to achieve cooling requirements. Conventional cooling equipment is inappropriate for extracting heat from microchips within the minimal surface area. Microchannel technology appeared as a next-generation heat exchanger for the given heat duty. In the classical case of accounting, micro-heat exchangers both axial and transverse wall conduction effects is usually neglected. However, from the year 2005 onwards, researchers identified conduction dominance at fluid velocity is zero zones at the interface, which created balance between conduction–convection currents, finally included axial wall/heat conduction effects to a general model. This present study made a comparative evaluation fluid flow, heat transfer characteristics, thermal performance (TP) based on geometrical parameters, substrate materials and discusses previous issues, and current issues-based future research directions. Till today, based on applications of microchannels in thermal management, several experimental and numerical investigations have been reported for further improvement in TP. However, many researchers are still trying to accomplish things over a long period. Therefore, an overview of previous studies is furnished in the present study to assist researchers in this area much useful for further improvement.

Experimental and numerical analysis of multi-layer micro channel applied to parabolic solar concentrator

There are numerous applications for micro-channel technology, but it has just a few applications in solar collectors. Therefore this research makes a clear contribution in this field by using a new design absorber in the concentrator, and the reflector was designed to focus the solar radiation on two sides. The solar concentrator system was attached to the tracking system to maintain the parabolic collector's perpendicularity to sun rays. This study investigates the experimental and numerical effects of the micro-channel technique on solar concentrator performance for different velocity values to meet the need for temperature differences, which gives Reynolds numbers varying from 1011 to 3273. The absorber plate was made from aluminum metal with 44 rectangular microchannels (0.3 m in length, 0.02 m in width, and 0.0009 m in height). The result indicated that the two-axis tracking system would increase output temperature by roughly 18 %. Outlet air temperature decreased significantly by 13.9 °C with changing flow rate from 0.009339 to 0.030235 kg/s. The highest efficiency was 91 % in March, 89 % in November, 80 % in February, 69.8 % in December and 65.5 % in January. A good agreement was obtained between numerical and experimental with a maximum deviation of 1.4, 1.7, 9.4 and 8.88 % for the glass cover, absorber plate, upper channel and lower channel, respectively.

Numerical modelling for design of microchannel reactors: Application to hydrogen production from methanol by steam reforming

Microchannel reactors involve chemical-reaction engineering problems in their design and operation, with heat and mass transfer considerations dominating their practicability and efficiency. Study of the fundamental transport phenomena necessitates their description in sophisticated mathematical form. The present study seeks to address this particular problem by investigating the effects of various factors on the transport processes in a heterogeneously catalysed microchannel steam reforming reactor. Numerical modelling for reactor design was performed using a model that accounted for complex catalyst dynamics. Dimensionless number analyses were conducted to understand the nature of the transport processes. The reactor performance was evaluated by means of various parameters, and design recommendations were made. Different operating limit lines were mapped out, and various definitions of energy efficiency were distinguished. The results indicated that the use of microchannel technology enables the achievement of unusually favourable conversion. While mass-transfer limitations are dominant, the reaction is practically feasible at millisecond contact times. A maximum output power in excess of 70 watts per channel can be reached, and energy efficiencies up to about 70 percent are available. The operating limit line can be changed as desirable to maintain the desired product yield throughout the range of conditions. While an optimum velocity for maximum efficiency exists, the flow rate and catalyst loading must be carefully adjusted to simultaneously control the conversion and maximum power within certain needed limits.

Comparison of Anodic and Au-Au Thermocompression Si-Wafer Bonding Methods for High-Pressure Microcooling Devices.

Silicon-based microchannel technology offers unmatched performance in the cooling of silicon pixel detectors in high-energy physics. Although Si-Si direct bonding, used for the fabrication of cooling plates, also meets the stringent requirements of this application (its high-pressure resistance of ~200 bar, in particular), its use is reported to be a challenging and expensive process. In this study, we evaluated two alternative bonding methods, aiming toward a more cost-effective fabrication process: Si-Glass-Si anodic bonding (AB) with a thin-film glass, and Au-Au thermocompression (TC). The bonding strengths of the two methods were evaluated with destructive pressure burst tests (0-690 bar) on test structures, each made of a 1 × 2 cm2 silicon die etched with a tank and an inlet channel and sealed with a plain silicon die using either the AB or TC bonding. The pressure resistance of the structures was measured to be higher for the TC-sealed samples (max. 690 bar) than for the AB samples (max. 530 bar), but less homogeneous. The failure analysis indicated that the AB structure resistance was limited by the adhesion force of the deposited layers. Nevertheless, both the TC and AB methods provided sufficient bond quality to hold the high pressure required for application in high-energy physics pixel detector cooling.

Current Status and Prospect of Microchannel Research

The application of microchannel in engineering field is becoming more and more extensive, which has attracted extensive attention of researchers at home and abroad. In the field of microelectronics technology, if the heat cannot be dissipated effectively, the working temperature of electronic devices will be seriously affected. Microchannel is an effective means to solve the heat dissipation problem. This paper shows the research status of microchannels by enumerating the research achievements of microchannels at home and abroad. By using the methods of literature review and comparison, four main problems of microchannel research in China are pointed out: the commercial production of microchannel. The problems caused by the application of micro channels to products, the risk of slow technological innovation is decreasing, the potential for future growth and the lack of uniform industry standards. Finally, the future development and research of microchannel are prospected, and some suggestions are put forward to provide reference for the future research and development of microchannel technology in China.

Experimental Study on Microchannel with Addition of Microinserts Aiming Heat Transfer Performance Improvement

Microchannel technology rapidly established itself as a practicable solution to the problem of the removal of extremely concentrated heat generation in present-day cooling fields. By implementing a better design structure, altering the working fluids and flow conditions, using various materials for fabrication, etc., it is possible to increase the heat transfer performance of microchannels. Two parameters that affect how well a microchannel transfers heat were only recently coupled, and the complicated coupling of the parameter that affects how well a microchannel sink transfers heat is still not well understood. The newest industrial developments, such as micro-electro-mechanical systems, high performance computing systems, high heat density generating future devices, such as 5G/6G devices, fuel cell power plants, etc., all present thermal challenges that require the use of microchannel technology. In this paper, single-phase flow in microchannels of various sizes, with or without microinserts, is described in terms of its thermal-fluid flow properties, including fluid flow characteristics and heat transfer characteristics considering the compound effects of variations of channel size and addition of microinserts. The trials were carried out using distilled water that had thermo-physical characteristics that varied with temperature. A microchannel with microinserts was developed for managing the high heat generation density equipment. The fluid flow and heat transfer characteristics are explored and analyzed for Reynolds numbers ranges from 125 to 4992, for 1 mm channel size, and from 250 to 9985, for 2 mm channel size. The cooling performance criteria are pressure drop characteristics, heat transfer characteristics, and overall performance, whereas the testing parameters were chosen for the variations in channel size and the addition of microinserts. The influence of inserting microinserts on microchannels is discussed. Results suggest that by inserting microinserts, the performance of the heat transfer of microchannels is significantly improved and, also, fluid flow resistance is increased. The criteria of the thermal performance factor are employed to assess the overall performance of the microchannel. Significant intensification of heat transfer is observed with indication that the addition of microinserts to microchannels and reduction in channel sizes exhibited improved overall performance.

Application of optimized microchannel separator to maximize the reuse efficiency of purified water in the petrochemical industry

In the petrochemical industry, water is purified through a steam stripping system. However, the generated water contains approximately 5–10 mg/L of suspended solids (SS), which does not meet the high-pressure air-cooled water standard (SS ≤0.2 mg/L) proposed by the American Petroleum Institute (API). Therefore, additional efforts are needed to reduce the content of SS and facilitate the recycling of water resources, in addition to saving energy and reducing emissions. This study proposed a physical separation method based on microchannel technology, after which a laboratory-scale experimental study was conducted to assess the influence of important parameters such as bed height, filler type, and particle size on the separation performance of the microchannel separator. Next, a 1 m3/h pilot-plant was established to comprehensively evaluate the removal efficiency and operational stability of SS in the purified water. Our study found that in weakly alkaline purified water, when the filler bed height was greater than 1500 mm, and using 0.105–0.125 mm glass beads, the effluent SS could reach 0.2 mg/L and purified water could be stably obtained with a 95% recovery rate. Therefore, it was estimated that a 100 m³ /h industrial-scale installation could save approximately $1100,000 in salt water and effluent treatment alone, in addition to reducing the annual CO2 emissions by approximately 15,000 t. This is a low-cost method that does not require any additional chemicals while delivering high-efficiency separation, which reduces the demand for fresh water by petrochemical companies, increases corporate benefits, and meets the requirements of emission reduction and environmental protection.

Thermophysical property evaluation of β-cyclodextrin modified ZrO2 nanofluids for microchannel heat exchange

Microchannel technology is an effective method to solve the heat transfer of microelectronics. Nanofluids are considered to have great application potential in microchannel heat exchangers. In this experiment, β-cyclodextrin (β-CD) was used to modify ZrO2 nanoparticles. The morphology, functional group, and crystal structure of the nanoparticles before and after modification were studied. Ethylene glycol aqueous solution-based nanofluids were prepared using a two-step method. Its physical properties were studied. The modified nanofluid has better stability. The thermal conductivity of the nanofluid was measured and the mathematical model was analyzed. The results showed that the nanofluid with a concentration of 0.10 vol% was 37.82% higher than the base fluid at 60 °C. The results of the mathematical analysis indicate that the fabrication of nanofluids using β-cyclodextrin-modified ZrO2 has great potential for application in heat transfer in microelectronic microchannels.

Imidazole-methane sulfonic ionic liquids used for catalytic alkylation desulfurization and enhancement of microchannel technology

Imidazole-methane sulfonic ionic liquids (C4(MIM)-MSA) were synthesized and used for catalytic alkylation of thiophene. The determination of sulfur content in alkylated desulfurized oil shows that the ionic liquid has excellent alkylation desulfurization effect. Compared with pure acid catalyst, ILs catalytic reaction has higher selectivity. The alkylation desulfurization mechanism of ionic liquid was proved by the determination of oil component changes before and after desulfurization and the characterization of ionic liquid structure. Microchannel technology is used to enhance alkylation reaction, and the optimum reaction conditions are experimentally selected. The microchannel reactor can shorten the alkylation desulfurization reaction time significantly and only need 2 min to complete the reaction, which is much lower than the conventional stirring reaction time of 30 min. The desulfurization rate of model oil is 93.8% and FCC desulfurization rate is 96.3% (final distillation point is 160 °C).

Peculiarities of hydrogen production using methane steam reforming in a microstructured reactor-heat exchanger

This paper presents the description of the rhodium catalyst synthesis and the results of numerical study of the methane-steam reforming in a microstructured reactor-heat exchanger. The kinetics of the reforming reactions on a synthesized catalyst was determined using the numerical simulations and experimental data on activation energy of the methane reactions. It allows finding the characteristics of methane steam reforming that can be used for optimization of the microstructured reactor implementing the microchannel technology.

OPTIMIZATION OF THE MICROELECTROMECHANICAL PROPERTIES OF HEAT EXCHANGE SYSTEMS THROUGH MICROCHANNEL TECHNOLOGY


 Abstract: Performance of microchannel heat exchangers is highly dependent on their geometry and shape. Hence, the structural design is as equally important as the material components. This paper expounds the development and applications of microchannel technology thereby proposing an optimal applicability on the microelectromechanical properties of heat exchange systems.

Methane sulfonic acid ionic liquid extraction of gasoline desulfurization process and enhancement of microchannel technology

Methane sulfonic acid (MSA) was used as anion to synthesize a series of ionic liquids and its desulfurization performance was evaluated by extraction. The basic physical properties and structural properties of the ionic liquids were evaluated, and it was proved that the ionic liquids could be used and separated well in liquid–liquid extraction desulfurization (EDS) system. The liquid–liquid extraction desulfurization system was enhanced by microchannel technology. The effects of microchannel diameter, extraction temperature, residence time and extraction stage on extraction efficiency were discussed. In the microchannel extraction system, this extraction equilibrium time can be reduced to 60 s from more than 10–15 min or longer in the conventional intermittent extraction techniques, which effectively reduces the synthesis and production cost. This finding may provide some reference for the further study of the micro-reaction technology in the deep removal of sulfur compounds from gasoline by ionic liquid, and further optimize the operating conditions.

Mini-scale pulsating heat pipe cooling systems for high-heat-flux electronic equipment

This paper presents a novel passive two-phase cooling system for efficient thermal management of high-heat-flux electronic equipment, namely a mini-scale, flat-plate pulsating heat pipe, by executing experiments on a test bench. Furthermore, cooling tests on an actual 1-U server are also shown. The pulsating heat pipe used in this study is designed and manufactured with micro-channel technology where passive two-phase flow circulation is promoted by the inherent two-phase instability and the competing effect between nucleate boiling and thin-film evaporation. Pulsating heat pipes properly operate with gravity (in vertical orientations) and without gravity (in horizontal orientations) and they are an optimal solution to dissipate a large amount of heat without the need of active drivers (absence of pumping power). The cooling capabilities of the proposed pulsating heat pipe were investigated using different near zero global warming potential refrigerants at various filling ratios to find the optimal thermal performance up to 800 W (corresponding to a heat flux of 25 W/cm2). The minimum overall thermal resistance was measured to be 0.065 K/W, which includes the thermal interface material and the secondary side. This paper shows that passive two-phase cooling using pulsating heat pipes can be a very promising and reliable technology for achieving high power dissipations of next-generation datacentres (and electronic equipment in general).

Numerical Investigation on Cavitation Suppression of Microchannel over a NACA0012 Hydrofoil

To find a better method to suppress cavitation, a microchannel design connecting the internal low-pressure area with the outside is proposed for the first time in this paper; the method was adopted to replenish fluid in the interior of the low-pressure area to inhibit cavitation. Through numerical simulation, it is found that the size and position of microchannel have a certain influence on the cavitation inhibition. The results show that the generation and development of cavitation, under the same working conditions, can be effectively restrained by adopting appropriate microchannel (x = 0.05 c, d = 6 cm). Compared with the original hydrofoil, the scale of cavitation is reduced by nearly 50%, and its turbulent kinetic energy remains unchanged. Therefore, it is considered that microchannel technology, as a new means of cavitation suppression, is of great significance to other types of fluid machinery.

A critical review on measures to suppress flow boiling instabilities in microchannels

Due to the development of the electronic components, concentrator photovoltaic, fuel cell, etc., the cooling requirement of the devices increases rapidly. Due to the higher heat transfer and compact design of the microchannel technology, it has been widely considered and investigated to solve the increasing heat flux. Boiling heat transfer is an effective way to dissipate a mass of heat using the latent heat of phase change. Hence, comparing with the single phase liquid flow, flow boiling in microchannel utilizes both advantages of micro scale effect and phase change effect, and can realize a much higher heat flux. Therefore, it becomes a critical way for super high heat dissipation. However, the procedure of the phase change and two phase flow may lead to instability, which can seriously inhibit the heat transfer performance of coolant in microchannel. To tackle with the flow boiling instability, a number of methods were proposed and reported. Therefore, in this paper, to effectively improve the flow boiling in microchannel heat exchanger, the cutting-edge control technologies in this field were reviewed, categorized and summarized, and the future trend of the research was presented.

Micro-Channel Heat Sink: A Review

The method to cool a high heat flux device is an important research direction for the heat exchanger design. Micro-channels are an effective heat exchange structure both for single-phase and two-phase flow. In this paper, the heat transfer correlations of single-phase, two-phase and nanofluid in a micro-channel are discussed and analyzed. The correlations of pressure drop for single-phase and two-phase fluids are also presented. Excluding the different working fluids used in the micro-channel, the diameter and aspect ratio, shape and structure, surface roughness, internal and external factor and layout of micro-channel pipe are considered to analyze their influence on the heat transfer performance and pressure drop. Micro-channel technology applications include industry, air-conditioning, solar energy systems, heat pipe technology and computer data center cooling. Compared to the conventional heat exchangers used in these fields, a micro-channel heat sink showed a much better heat transfer coefficient and low volume, indicating that it is a good choice and has huge potential for cooling application. Finally, existing problems and future scopes are described, and drawing up design standard, experimental and simulated methods for evaluating its performance are the urgent actions which need to be carried out. This review paper serves as guidance for researchers to design and predict the performance of micro-channel heat sinks.

Experimental Performance Evaluation of Tubular Manifold Heat Exchanger

Abstract The present work demonstrates the use of manifold microchannel technology in conjunction with conventional macrogeometries to achieve superior performance compared to traditional heat exchangers. A novel tubular manifold heat exchanger is designed using three-dimensional (3D) printed manifold and conventional double enhanced tube. The experiments are performed using water as the working fluid and the manifold side heat transfer coefficient up to 9538 Wm−2K−1 with a low flowrate of 4.25 lpm is achieved with as low pressure drop as 323 Pa. A comparison with respect to thermal hydraulic performance of the results with a plate heat exchanger shows clear advantage of the proposed exchanger. Overall, microscale heat transfer characteristics are obtained by using relatively simple and economical fabrication techniques.