Статті в журналах з теми "Cooling"
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1
Wang, Chen, Chunhua Wang, and Jingzhou Zhang. "Parametric Studies of Laminated Cooling Configurations: Overall Cooling Effectiveness." International Journal of Aerospace Engineering 2021 (February 10, 2021): 1–15. http://dx.doi.org/10.1155/2021/6656804.
Анотація:
Combing the advantages of film cooling, impingement cooling, and enhanced cooling by pin fins, laminated cooling is attracting more and more attention. This study investigates the effects of geometric and thermodynamic parameters on overall cooling effectiveness of laminated configuration, and model experiments were carried out to validate the numerical results. It is found that the increases in film cooling hole diameter and pin fin diameter both result in the increase in cooling effectiveness, but the increases in impingement hole diameter, impingement height, and spanwise hole pitch degrade the cooling performance. The increase of the coolant flow rate causes the increase in cooling efficiency, but this effect becomes weaker at a high coolant flow rate. The coolant-to-mainstream density ratio has no obvious effect on cooling effectiveness but affects wall temperature obviously. Moreover, based on the numerical results, an empirical correlation is developed to predict the overall cooling efficiency in a specific range, and a genetic algorithm is applied to determine the empirical parameters. Compared with the numerical results, the mean prediction error (relative value) of the correlation can reach 8.3%.
2
Che Sidik, Nor Azwadi, and Shahin Salimi. "The Use of Compound Cooling Holes for Film Cooling at the End Wall of Combustor Simulator." Applied Mechanics and Materials 695 (November 2014): 371–75. http://dx.doi.org/10.4028/www.scientific.net/amm.695.371.
Анотація:
Gas turbine cooling can be classified into two different schemes; internal and external cooling. In internal cooling method, the coolant provided by compressor is forced into the cooling flow circuits inside turbine components. Meanwhile, for the external cooling method, the injected coolant is directly perfused from coolant manifold to save downstream components against hot gases. Furthermore, in the latter coolant scheme, coolant is used to quell the heat transfer from hot gas stream to a component. There are several ways in external cooling. Film cooling is one of the best cooling systems for the application on gas turbine blades. This study concentrates on the comparison of experimental, computational and numerical investigations of advanced film cooling performance for cylindrical holes at different angles and different blowing ratios in modern turbine gas.
3
Shi, Li, Zhiying Sun, and Yuanfeng Lu. "The Combined Influences of Film Cooling and Thermal Barrier Coatings on the Cooling Performances of a Film and Internal Cooled Vane." Coatings 10, no. 9 (September 5, 2020): 861. http://dx.doi.org/10.3390/coatings10090861.
Анотація:
This paper presents a numerical investigation on the combined influences of film cooling and thermal barrier coatings (TBCs) on the cooling performances of a NASA C3X guide vane. The results show that: (1) film cooling on the pressure side is more effective than suction side, especially on the trailing edge where multiple cooling and thermal protection techniques include internal cooling and TBCs are necessary. (2) TBCs show positive and negative roles in improving cooling performance at the same time for the coated vane with or without film cooling. Without film cooling, TBCs show negative roles on the regions with lower temperature external hot gas, which is caused by flow acceleration from the stagnation line of the suction side. (3) Internal cooling improvement caused by coolant introduction leads to a larger cooling effectiveness inclement due to TBCs near coolant plenums and film cooling holes. However, the influence of TBCs on cooling effectiveness increment goes down and even shows negative roles on the regions away from coolant plenums and under the effective coverage of the film cooling. (4) Improving the convective heat transfer of coolant with the wall of coolant plenums and film cooling holes is the guarantee of improving the cooling performance of a coated vane.
4
Harrington, Mark K., Marcus A. McWaters, David G. Bogard, Christopher A. Lemmon, and Karen A. Thole. "Full-Coverage Film Cooling With Short Normal Injection Holes." Journal of Turbomachinery 123, no. 4 (February 1, 2001): 798–805. http://dx.doi.org/10.1115/1.1400111.
Анотація:
An experimental and computational investigation was conducted on the film cooling adiabatic effectiveness of a flat plate with full coverage film cooling. The full coverage film cooling array was comprised of ten rows of coolant holes, arranged in a staggered pattern, with short L/D=1, normal coolant holes. A single row of cooland holes was also examined to determine the accuracy of a superposition prediction of the full coverage adiabatic effectiveness performance. Large density coolant jets and high mainstream turbulence conditions were utilized to simulate realistic engine conditions. High-resolution adiabatic effectiveness measurements were obtained using infrared imaging techniques and a large-scale flat plate model. Optimum adiabatic effectiveness was found to occur for a blowing ratio of M=0.65. At this blowing ratio separation of the coolant jet immediately downstream of the hole was observed. For M=0.65, the high mainstream turbulence decreased the spatially averaged effectiveness level by 12 percent. The high mainstream turbulence produced a larger effect for lower blowing ratios. The superposition model based on single row effectiveness results over-predicted the full coverage effectiveness levels.
5
Friedrichs, S., H. P. Hodson, and W. N. Dawes. "The Design of an Improved Endwall Film-Cooling Configuration." Journal of Turbomachinery 121, no. 4 (October 1, 1999): 772–80. http://dx.doi.org/10.1115/1.2836731.
Анотація:
The endwall film-cooling cooling configuration investigated by Friedrichs et al. (1996, 1997) had in principle sufficient cooling flow for the endwall, but in practice, the redistribution of this coolant by secondary flows left large endwall areas uncooled. This paper describes the attempt to improve upon this datum cooling configuration by redistributing the available coolant to provide a better coolant coverage on the endwall surface, while keeping the associated aerodynamic losses small. The design of the new, improved cooling configuration was based on the understanding of endwall film-cooling described by Friedrichs et al. (1996, 1997). Computational fluid dynamics were used to predict the basic flow and pressure field without coolant ejection. Using this as a basis, the above-described understanding was used to place cooling holes so that they would provide the necessary cooling coverage at minimal aerodynamic penalty. The simple analytical modeling developed by Friedrichs et al. (1997) was then used to check that the coolant consumption and the increase in aerodynamic loss lay within the limits of the design goal. The improved cooling configuration was tested experimentally in a large-scale, low-speed linear cascade. An analysis of the results shows that the redesign of the cooling configuration has been successful in achieving an improved coolant coverage with lower aerodynamic losses, while using the same amount of coolant as in the datum cooling configuration. The improved cooling configuration has reconfirmed conclusions from Friedrichs et al. (1996, 1997): First, coolant ejection downstream of the three-dimensional separation lines on the endwall does not change the secondary flow structures; second, placement of holes in regions of high static pressure helps reduce the aerodynamic penalties of platform coolant ejection; finally, taking account of secondary flow can improve the design of endwall film-cooling configurations.
6
Ding, Yuzhang, Haocheng Ji, Rui Liu, Yuwei Jiang, and Minxiang Wei. "Study of the thermal behavior of a battery pack with a serpentine channel." AIP Advances 12, no. 5 (May 1, 2022): 055028. http://dx.doi.org/10.1063/5.0089378.
Анотація:
To effectively enhance the thermal security of the Li-ion battery packs used in the electric vehicle industry, novel cooling systems equipped with serpentine channels are established. Then, the heat generation model is established and verified experimentally. In this research study, the structure of the cooling channel, the coolant velocity, the coolant temperature, and the coolant flow direction are considered to be the influencing factors. The results demonstrate that, by adopting the serpentine cooling channel, a better thermal conductivity can be obtained, and the type-B cooling system possesses a more reasonable structure. For different types of liquid cooling systems, the coolant temperature has a small influence on the temperature nephogram; however, for the same type of system, the coolant temperature strongly influences the temperature distribution. Similarly, the temperature difference is only related to the type of cooling system, with ∼6.09 and 5.53 K obtained for the type-A and type-B cooling systems, respectively. Furthermore, allowing the coolant in the serpentine cooling channels to flow in opposite directions can lower the value of the maximum temperature and temperature difference.
7
Zulfikar, Zulfikar. "Penambahan Water Coolant Pada Cooling Tower Tipe Counter Flow." Jurnal Mesin Nusantara 1, no. 2 (August 27, 2019): 85–92. http://dx.doi.org/10.29407/jmn.v1i2.13566.
Анотація:
Cooling tower adalah alat penukar kalor dengan fluida kerja air dan udara yang berfungsi mendinginkan air dengan kontak langsung dengan udara yang mengakibatkan sebagian kecil air menguap. Dalam kebanyakan cooling tower yang bekerja pada sistem pendinginan udara menggunakan pompa sentrifugal untuk menggerakkan air vertikal ke atas melintasi menara. Semua cooling tower yang bekerja akan melepaskan kalor melalui kondensor, refrigeran akan melepas kalornya kepada cooling tower sehingga air menjadi panas. Selanjutnya air panas ini akan dipompakan ke cooling tower. Dalam Penelitian ini peneliti akan menambahkan coolant yang kita tahu berfungsi sebagai pendingin. Tujuan penelitian ini adalah untuk mengetahui pengaruh penambahan water collant terhadap efektifitas pendinginan cooling tower. Penelitian terdahulu yang sudah pernah dilakukan adalah meneliti kinerja cooling tower dan efektifitas pendinginan cooling tower tersebut.
Hasil penelitian diperoleh suhu awal air yang masuk ke cooling tower adalah 50 ᵒC dan suhu air setelah diproses di colling tower tersebut adalah 40 ᵒC untuk water coolant merk A, sedangkan untuk water coolant merk B adalah 38 ᵒC . Dengan hasil ini dapat diketahui bahwa dengan penambahan coolant terhadap kinerja colling tower mempengaruhi efektivitas pendinginan cooling tower tersebut.
8
Sadov, V. V., and N. I. Kapustin. "AUTOMATED INSTALLATION FOR MILK COOLING USING A NATURAL COOLING AGENT." Vestnik Altajskogo gosudarstvennogo agrarnogo universiteta, no. 11 (2021): 116–22. http://dx.doi.org/10.53083/1996-4277-2021-205-11-116-122.
Анотація:
In the chain from milk production to the sale of dairy products, the process of ensuring the required temperature is the main one. Moreover, to cool the milk, the tempera-ture of the cooling agent should be above milk freezing. Taking into account the fact that the process of cooling and storing milk in a chilled form imposes strict requirements for reliability and quality of management on farms, compressor refrigeration units have been used in recent years despite high energy consumption. Theanalysis of technical solu-tions in this direction by the example of farms of the Altai and Novosibirsk Regions showed that during the greatest boom of the livestock industry, film-tray, spray-cooling tow-er, and pipe and tank installations using natural cooling agents were widely used. Taking into account the climatic features of the area when choosing water cooling units as an intermediate coolant made it possible to significantly reduce energy consumption for milk cooling especially in winter. However, the complexity of controlling the process of preparing the intermediate coolant with unpredictable environmental parameters did not allow for high reliability and quality of manual control. A device for cooling the in-termediate coolant with the main -natural cold in winter with an automatic direct-acting regulator that provides the required operating mode of the cooling unit is proposed. The variants of automatic device operation both when the outdoor air temperature decreases and increases are con-sidered. An automated installation for cooling the interme-diate coolant with natural cold may be recommended both for cattle farms and processing enterprises
9
Wang, J. H., J. Messner, and H. Stetter. "An Experimental Investigation on Transpiration Cooling Part II: Comparison of Cooling Methods and Media." International Journal of Rotating Machinery 10, no. 5 (2004): 355–63. http://dx.doi.org/10.1155/s1023621x04000363.
Анотація:
This article attempts to provide a cooling performance comparison of various mass transfer cooling methods and different cooling media through two experiments. In the first experiment, pressurized air was used as a cooling medium and two different circular tubes were used as specimens. One is made of impermeable solid material with four rows of discrete holes to simulate film cooling, and the other consists of sintered porous material to create a porous transpiration cooling effect. The natures of transpiration cooling and film cooling including leading and trailing edge injection cooling were compared. This experiment found that by using a gaseous cooling medium, transpiration cooling could provide a higher cooling effect and a larger coolant coverage than film cooling in the leading stagnation region, and on the side of the specimen at the same coolant injection flow rates; but in the trailing stagnation region, the traditional coolant injection method through discrete film holes might be better than transpiration cooling, especially for turbine blades with thin trailing edges. In the second experiment, the cooling effects of gaseous and liquid media on the same porous tube's surface were compared. This experiment showed that the porous areas cooled using gaseous and liquid cooling media were almost identical, but the cooling effect of liquid evaporation was much higher than that of gaseous cooling, especially in the leading and trailing stagnation regions of turbine blades. This important discovery makes it possible to solve the stagnation region problems in turbine blade cooling.
10
Madyshev, Ilnur, Vitaly Kharkov, Anna Mayasova, and Ravshan Kurbangaliev. "Cooling efficiency of hybrid cooling tower with finned tube radiator." E3S Web of Conferences 458 (2023): 01003. http://dx.doi.org/10.1051/e3sconf/202345801003.
Анотація:
Hybrid cooling towers are a new type of equipment that can be used in cooling water circuits. In this work, a hybrid cooling tower is developed, in which inclined corrugated plates are used as a fill, and the circulating liquid flows through an internal tubular radiator, the finned surface of which is continuously washed by the coolant water. The purpose of the work is to perform an experimental evaluation of the cooling efficiency of the developed hybrid system used for circulating water cooling. It was obtained that at the wetting density of the coolant water equal to 28.3 m3/(m2·h) and the mass flow rate of the circulating water in the tubular radiator of 0.0135 kg/s, the cooling efficiency of the developed cooling tower can reach 38.6%.
11
Song, Hanlin, Meng Zheng, Zheshu Ma, Yanju Li, and Wei Shao. "Numerical simulation of thermal performance of cold plates for high heat flux electronics cooling." Thermal Science, no. 00 (2023): 261. http://dx.doi.org/10.2298/tsci230715261s.
Анотація:
High heat flow density electronic components need cooling plates with strong heat exchange capacity to maintain temperature balance. To obtain better cooling performance, four different flow channel types of cooling plates are designed, including an S-type channel, Z-type channel, mosaic channel and double-layer channel. The maximum temperature of the cooling plate, outlet temperature and pressure drop under different working conditions and coolant are analyzed by numerical simulation. The simulation results show that the double-layer channel design can effectively enhance the heat transfer effect of the cooling plate and reduce the pressure drop. The maximum temperature of the cooling plate of the double-layer flow channel is 6.88 ?C lower than that of the Z-type flow channel. Moreover, increasing the inlet flow rate and lowering the coolant inlet temperature can improve the cooling performance of the cold plate, but increasing the inlet flow rate will lead to an increase in the pressure loss of the cold plate. When the coolant of the double-layer channel cooling plate is 20% ethylene glycol-water solution, the cooling performance is better than the other three coolants. Other channel cooling plates perform better with water as the coolant.
12
Gao, Y., S. Zhou, and Y. Zhang. "A Preliminary Study of Variable Strength Activation of Coolant for Precision Machining." Advanced Materials Research 76-78 (June 2009): 635–40. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.635.
Анотація:
A new active cooling method is proposed for increased cooling effectiveness of coolant in grinding. It is based on variable strength activation of coolant together with active cooling to allow better machining heat transfer through mist evaporation. Multiple actuators are used through superposition and focusing. A device of variable strength coolant activation has been developed. Preliminary experimental tests were conducted to test the feasibility of the proposed cooling method. It is found that, using the proposed variable strength activation, an improvement of 87.6% in Ra value and 71.9% in Rq value were obtained when compared with the existing activated and cooled coolant cooling method.
13
Adzhar, M. S. M., M. N. Harun, and A. P. M. Saad. "Cooling channel selection for big rectangular plastic parts in injection molding." IOP Conference Series: Materials Science and Engineering 1291, no. 1 (September 1, 2023): 012022. http://dx.doi.org/10.1088/1757-899x/1291/1/012022.
Анотація:
Abstract There are various of types cooling channel designs that have been explored by many researchers to find the best cooling channel that resulted in the optimum results in the injection molding process. The previous research reported that the correct selection of cooling channels in mold design affects the quality of the product and the total cycle time, thus it affected the quality and profit in the manufacturing [1]. The problem in mold design is selecting the correct cooling channel design to ensure the heat transfer distribution is in uniform condition. This paper analysed the effectiveness of four types of different cooling channel designs, the diameter size of the cooling channel, and the variable of coolant temperature in the big rectangular plastic product with the same injection parameters and material type. The objective is to determine the effect of using different cooling channel designs on the cooling time and warpage effect with different coolant temperatures. The commercial mold flow software was used to simulate the injection behaviour to determine the quality of the warpage and total cooling time in the injection molding process. The result found that using a cooling channel type with arrays of the baffle, array bubbler, and conformal cooling channel can reduce the cooling time by almost 50% compared to the conventional cooling channel. The increased coolant temperature in the cooling channel also affects the increase in the cooling time.
14
Somasekharan, Nithin, A. R. Srikrishnan, Harihara Sudhan Kumar, Krishna Prasad Ganesh, Akram Mohammad, and Ratna Kishore Velamati. "Enhancement of Film Cooling Effectiveness in a Supersonic Nozzle." Entropy 25, no. 3 (March 10, 2023): 481. http://dx.doi.org/10.3390/e25030481.
Анотація:
Film cooling as applied to rocket nozzles is analyzed numerically with emphasis on the assessment of the effect of the mixing of coolant with the hot stream. Cooling performance, as characterized by cooling effectiveness, is studied for three different coolants in the three-dimensional, turbulent flow field of a supersonic convergent-divergent nozzle operating with a hot stream temperature of 2500 K over a range of blowing ratios. The coolant stream is injected tangentially into the mainstream using a diffuser-type injector. Parameters influencing the effectiveness, such as coolant injector configuration and mixing layer, are analyzed. Thermal and species mixing between the coolant and the mainstream are investigated with regard to their impact on cooling effectiveness. The results obtained provide insight into the film cooling performance of the gases and the heat transfer characteristics associated with these three gases. An injector taper angle of 30° results in the most effective cooling among the configurations considered (0°, 15°, 30° and 45°). Mixing of the coolant with the hot stream is examined based on the distributions of velocity, temperature and species. The higher values of cooling effectiveness for Helium are attributed to its thermophysical properties and the reduced rate of mixing with the hot stream. The results further indicate that through optimization of the blowing ratio and the coolant injector configuration, the film cooling effectiveness can be substantially improved.
15
Kuo, Chil-Chyuan, Jing-Yan Xu, Yi-Jun Zhu, and Chong-Hao Lee. "Effects of Different Mold Materials and Coolant Media on the Cooling Performance of Epoxy-Based Injection Molds." Polymers 14, no. 2 (January 11, 2022): 280. http://dx.doi.org/10.3390/polym14020280.
Анотація:
Metal additive manufacturing techniques are frequently applied to the manufacturing of injection molds with a conformal cooling channel (CCC) in order to shorten the cooling time in the injection molding process. Reducing the cooling time in the cooling stage is essential to reducing the energy consumption in mass production. However, the distinct disadvantages include higher manufacturing costs and longer processing time in the fabrication of injection mold with CCC. Rapid tooling technology (RTT) is a widely utilized technology to shorten mold development time in the mold industry. In principle, the cooling time of injection molded products is affected by both injection mold material and coolant medium. However, little work has been carried out to investigate the effects of different mold materials and coolant media on the cooling performance of epoxy-based injection molds quantitatively. In this study, the effects of four different coolant media on the cooling performance of ten sets of injection molds fabricated with different mixtures were investigated experimentally. It was found that cooling water with ultrafine bubble is the best cooling medium based on the cooling efficiency of the injection molded parts (since the cooling efficiency is increased further by about 12.4% compared to the conventional cooling water). Mold material has a greater influence on the cooling efficiency than the cooling medium, since cooling time range of different mold materials is 99 s while the cooling time range for different cooling media is 92 s. Based on the total production cost of injection mold and cooling efficiency, the epoxy resin filled with 41 vol.% aluminum powder is the optimal formula for making an injection mold since saving in the total production cost about 24% is obtained compared to injection mold made with commercially available materials.
16
Deng, Qinghua, Huihui Wang, Wei He, and Zhenping Feng. "Cooling Characteristic of a Wall Jet for Suppressing Crossflow Effect under Conjugate Heat Transfer Condition." Aerospace 9, no. 1 (January 6, 2022): 29. http://dx.doi.org/10.3390/aerospace9010029.
Анотація:
The leading edge is the critical portion for a gas turbine blade and is often insufficiently cooled due to the adverse effect of Crossflow in the cooling chamber. A novel internal cooling structure, wall jet cooling, can suppress Crossflow effect by changing the coolant flow direction. In this paper, the conjugate heat transfer and aerodynamic characteristics of blades with three different internal cooling structures, including impingement with a single row of jets, swirl cooling, and wall jet cooling, are investigated through RANS simulations. The results show that wall jet cooling combines the advantages of impingement cooling and swirl cooling, and has a 19–54% higher laterally-averaged overall cooling effectiveness than the conventional methods at different positions on the suction side. In the blade with wall jet cooling, the spent coolant at the leading edge is extracted away through the downstream channels so that the jet could accurately impinge the target surface without unnecessary mixing, and the high turbulence generated by the separation vortex enhances the heat transfer intensity. The Coriolis force induces the coolant air to adhere to the pressure side’s inner wall surface, preventing the jet from leaving the target surface. The parallel cooling channels eliminate the common Crossflow effect and make the flow distribution of the orifices more uniform. The trailing edge outlet reduces the entire cooling structure’s pressure to a low level, which means less penalty on power output and engine efficiency.
17
Zulhafril, Herman, Jasman Jasman, and Kimberly June Tespoer. "The Effect of Cooling Media on Tensile Strength of Medium Carbon Steel in Post Welding Process Using Electric Welding (SMAW) with E7018 Electrodes." Teknomekanik 3, no. 2 (December 10, 2020): 62–69. http://dx.doi.org/10.24036/teknomekanik.v3i2.6472.
Анотація:
The use of cooling media in post welding process will affect the tensile strength of a material. This study aims to determine how much the influence of using cooling media in post welding and which cooling media is appropriate to use. The process is done by comparing the tensile strength of each cooling media, namely the cooling media of water, air, and coolant. The use of cooling media is carried out after the welding process, until the material that is ready to be welded reaches room temperature. Based on the experiments that have been conducted, the use of post-welding cooling media affects the tensile strength of medium carbon steel with the highest effect on the water cooling media, then the coolant media, and the lowest is the air cooling media. Therefore, the choice of the use of cooling media significantly affects the tensile strength of medium carbon steel in the post-welding process.
18
Wang, Wen, Jiahuan Cui, and Shaoxing Qu. "Effects of hole arrangement and trenched hole on multirow film cooling." AIP Advances 12, no. 4 (April 1, 2022): 045205. http://dx.doi.org/10.1063/5.0082980.
Анотація:
Multirow film cooling is an advanced cooling method to provide effective surface cooling for gas turbine components exposed to high temperature. In this paper, the performance of multirow film cooling under different configurations is investigated numerically. The geometrical parameters, including the hole arrangement, hole orientation, and trenched hole, are considered. The numerical setup is validated before the performances of different cooling configurations are compared. The flow and heat transfer characteristics of the various cooling configurations are analyzed, and the different row-to-row interactions are revealed. For the configurations with standard holes, the staggered arrangement of simple angle holes achieves better cooling efficiency than the counterpart with inline configuration, while the inline arrangement with opposite compound angle holes provides the best cooling efficiency. For the configurations with trenched holes, the trench promotes the coolant uniform mixing, and the coolant stays more close to the effusion plate. Thus, the multirow cooling efficiency with trenched holes is better than the cooling configurations with standard holes.
19
Li, Yi, Peng-Xiao Zhu, Cai Tang, and Zhi Sun. "Effects of Quenching Medium on Microstructure and Mechanical Properties of High Chromium Cast Iron." Crystals 12, no. 10 (September 21, 2022): 1332. http://dx.doi.org/10.3390/cryst12101332.
Анотація:
The cooling properties of different cooling mediums were studied and heat treatment of high chromium cast iron was carried out by different cooling mediums. The results showed that the maximum cooling rate, cooling rate at 300 °C and the quenching liquid cooling capacity of water at 20 °C was 193.6 °C/s, 88.6 °C/s and 2431.1, respectively. With the increase in PAG concentration, the maximum cooling rate and the cooling rate at 300 °C of the coolant decreased. The microstructure of high chromium cast iron treated by water cooling, 10% PAG coolant and 20% coolant was white carbide + tempered martensite + retained austenite, and its impact toughness and fracture toughness were gradually improved. The water-cooled high chromium cast iron had the highest Rockwell hardness of 66.2 HRC, good wear resistance of 0.6103 g and the greatest friction coefficient of 0.4233, the high chromium cast iron treated with 10% PAG had the best wear resistance of 0.5715 and the lowest friction coefficient 0.4182, the high chromium cast iron treated with 20% PAG had the lowest Rockwell hardness 58.1 HRC and the worst wear resistance 0.8213 g.
20
Pandey, Amit Kumar, Raghav Sharma, Nikhil, Divyanshu Choudhary, Neha Batra Bali, Maya Verma, Rashmi Menon, and Amit Tanwar. "Investigating the effect of coolant on cooling rate of engine oil used in automobile industry using Arduino interfaced temperature sensor." Physics Education 59, no. 2 (February 20, 2024): 025026. http://dx.doi.org/10.1088/1361-6552/ad2558.
Анотація:
Abstract Heat is lost by the system due to temperature difference between the hot object and surroundings. Two models which explain cooling are conduction-convection method and radiation method. During an automobile engine operation, both engine and engine oil get heated up. To overcome the problem of excessive heat generated, coolant is used to cool down the system. In present study, cooling rate of engine oil kept at high temperature was studied in the absence and presence of coolant. In the absence of coolant, engine oil follows the natural law of cooling stated by Newton and follows the exponential decay in temperature. Cooling rate constant was estimated through fitting first order and second order exponential decay with experimental data and found to be 3.35 × 10 − 4 s − 1 and 2.39 × 10 − 4 s − 1 (in first 50 min) respectively. Cooling rate in the presence of coolant was studied which shows rapid decrease in temperature for first few minutes which may be attributed to high heat capacity of coolant which surrounds the hot engine oil. After 50 min of cooling, temperature of both fluids found to decrease exponentially. Thus, the use of coolant was found to absorb the heat content from the engine oil rapidly in comparison to natural environment. Cooling rate constant were estimated through fitting experimental data and found to be 2.44 × 10 − 4 s − 1 and 2.43 × 10 − 4 s − 1 for engine oil and coolant respectively. The percentage change in temperature of oil in first two minutes in the presence of coolant was about 70% which is much higher in comparison to cooling without the use of coolant which was about 16% only. For data acquisition of temperature of engine oil and coolant, MAX6675 module with K-type thermocouple is used which were interfaced with the Arduino board.
21
Shakouri, Ehsan, Hossein Haghighi Hassanalideh, and Seifollah Gholampour. "Experimental investigation of temperature rise in bone drilling with cooling: A comparison between modes of without cooling, internal gas cooling, and external liquid cooling." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 232, no. 1 (November 18, 2017): 45–53. http://dx.doi.org/10.1177/0954411917742944.
Анотація:
Bone fracture occurs due to accident, aging, and disease. For the treatment of bone fractures, it is essential that the bones are kept fixed in the right place. In complex fractures, internal fixation or external methods are used to fix the fracture position. In order to immobilize the fracture position and connect the holder equipment to it, bone drilling is required. During the drilling of the bone, the required forces to chip formation could cause an increase in the temperature. If the resulting temperature increases to 47 °C, it causes thermal necrosis of the bone. Thermal necrosis decreases bone strength in the hole and, subsequently, due to incomplete immobilization of bone, fracture repair is not performed correctly. In this study, attempts have been made to compare local temperature increases in different processes of bone drilling. This comparison has been done between drilling without cooling, drilling with gas cooling, and liquid cooling on bovine femur. Drilling tests with gas coolant using direct injection of CO2 and N2 gases were carried out by internal coolant drill bit. The results showed that with the use of gas coolant, the elevation of temperature has limited to 6 °C and the thermal necrosis is prevented. Maximum temperature rise reached in drilling without cooling was 56 °C, using gas and liquid coolant, a maximum temperature elevation of 43 °C and 42 °C have been obtained, respectively. This resulted in decreased possibility of thermal necrosis of bone in drilling with gas and liquid cooling. However, the results showed that the values obtained with the drilling method with direct gas cooling are independent of the rotational speed of drill.
22
Yudiyanto, Eko, Ridho Surya Setiabudi, Agus Hardjito, Satworo Adiwidodo, and Bayu Pranoto. "Effect of Velocity and Type of Cooling Fluid on Peltier Heat Transfer for Car Cabin Cooling Applications." JOURNAL OF SCIENCE AND APPLIED ENGINEERING 5, no. 2 (September 25, 2022): 76. http://dx.doi.org/10.31328/jsae.v5i2.4036.
Анотація:
This research used the Peltier element as a car cabin cooler. This research aimed to compare the results of the lowest temperature produced by the Peltier element on the hot side. The design of this monitoring tool consists of LM35 as a temperature sensor and an electric velocity sensor to measure the velocity of the cooling fluid. Arduino Uno Microcontroller to control the system before being displayed to the LCD. The type of research used in this research is experimental research. In this study, variations in fluid flow velocity and type of cooling fluid were carried out. The fluid used is a mixture of water and water coolant with a ratio of 50%:50%. The results showed that the circulation of fluid cooling influences the temperature on the hot side of the Peltier. In cooling using water fluid, when the water pump rotates 4.5 liters/second, the temperature on the hot side of the Peltier is 36ᵒC. At the time of rotation of 13 liters/second, the temperature on the hot side of the Peltier is 32ᵒC. The difference between cooling using water fluid, water coolant, or a mixture of water and water coolant greatly affects the temperature produced on the cold side of the Peltier. In cooling using water, the lowest temperature produced reaches 8ᵒC. When the cooling using a fluid coolant, the lowest temperature reaches 6ᵒC. While cooling using a mixture of water and coolant, the lowest temperature reaches 3ᵒC. So it can be concluded that cooling using a mixture of water and water coolant is very effective compared to other fluid coolers.
23
Huang, Yao Ying, Xiao Man Lv, Dong Sheng Shen, and Kai Ping Tian. "Optimizing Control Trial of Concrete Dam in Middle-Later Cooling Age." Applied Mechanics and Materials 488-489 (January 2014): 350–53. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.350.
Анотація:
Optimizing control of concrete dam in middle-later cooling age is discussed in allusion to the complex multi-factor problems which includes pipe cooling temperature, pipe cooling flow and pipe cooling time. This paper suggested an optimizing control method of concrete dam in middle-later cooling age based on the temperature dynamic prediction model of pouring storehouse. Combining the current measured temperature, it calculated the temperature cooling curve based on the pipe cooling calculation formula without heat resource. Then optimal pipe cooling measures of concrete pouring storehouse is obtained by optimization algorithm with middle-later coolings target temperature. Because of the small amount of calculation of the temperature dynamic prediction model that based on the pipe cooling calculation formula without heat resource, so optimizing control model of concrete dam in middle-later cooling age is feasible.
24
Khudheyer, Ahmed F., and Hussein T. Dhaiban. "Numerical Study Of Heat Transfer In Cooling Passages Of Turbine Blade." Journal of Engineering 19, no. 3 (May 18, 2023): 342–56. http://dx.doi.org/10.31026/j.eng.2013.03.05.
Анотація:
As the temperature of combustion gases is higher than the melting temperature of the turbine materials, cooling of turbine parts in a gas turbine engine is necessary for safe operation. Cooling methods investigated in this computational study included cooling flow losses. Film-cooling is one typically used cooling method whereby coolant is supplied through holes passage, in present study the holes placed along the camber line of the blade. The subject of this paper is to evaluate the heat transfer that occur on the holes of blade through differentblowing coolant rates. The cases of this study were performed in a low speed wind tunnel with two tip gap at small and large (0.03 and 0.09cm) and multiple coolant flow rates through the film-cooling holes. Theblowing ratios was studied whereby coolant was injected from holes placed along the tip of a large scale blade model with Reynolds number (2.1 x 105 ) of the engine was matched. Results showed that baselineNusselt numbers on the holes were reduced along the holes passage, and heat transfer coefficient is high values at iterance region. Overall, the cooling by holes appears to be a feasible method for prolonging blade life.
25
An, Qing Long, Yu Can Fu, and Jiu Hua Xu. "The Application of Cryogenic Pneumatic Mist Jet Impinging in High-Speed Milling of Ti-6Al-4V." Key Engineering Materials 315-316 (July 2006): 244–48. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.244.
Анотація:
To solve the problems caused by high temperature in the cutting zone during high-speed milling of Titanium alloys, some cooling methods are employed, such as cold air cooling, high pressure coolant jet impinging, MQL, etc. But all have their shortfalls, both in cooling efficiency and environmental pollution. Here a new high efficiency cooling technology-cryogenic pneumatic mist jet impinging (CPMJI) cooling technology is offered. In this technology, a little quantity of coolant is carried by high pressure cryogenic air (-20) and reaches the machining zone in the form of mist jet. This paper mainly focuses on the cooling effects of CPMJI in high-speed milling of Titanium alloy Ti-6Al-4V, as compared with dry, cold air cooling and MQL conditions. CPMJI greatly reduced the temperature in cutting zone and flank wear of tool.
26
Ba, Wei, Xuesong Li, Xiaodong Ren, and Chunwei Gu. "Aero-thermal coupled through-flow method for cooled turbines with new cooling model." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 3 (September 25, 2017): 254–65. http://dx.doi.org/10.1177/0957650917731629.
Анотація:
The aero-thermal–coupled phenomenon is significant in modern cooled turbines, and an aero-thermal coupled through-flow method has previously been developed by the authors for considering the influence of heat transfer and coolant mixing in through-flow design. However, the original cooling model is not capable of calculating the distribution of the coolant mass flow rate and pressure loss in complex cooling structures. Therefore, in this paper, a one-dimensional flow calculation for the internal coolant is introduced into the heat transfer calculation to further improve the through-flow cooling model. Based on various empirical correlations, the cooling model can be used to simulate different cooling structures, such as ribbed channels and cooling holes. Three operating conditions were selected for verification of the NASA-C3X vane, which has 10 internal radial cooling channels. The calculated Nusselt number of internal cooling channels strongly agrees with the experimental data, and the predicted blade surface pressure and temperature distributions at mid span are also in good agreement with the experimental data. The convergence history of the meridional velocity and blade surface temperature demonstrates effective convergence properties. Therefore, the aero-thermal–coupled through-flow method with the new cooling model can provide a reliable tool for cooled turbine through-flow design and analysis.
27
Lin, Yuzhen, Bo Song, Bin Li, and Gaoen Liu. "Measured Film Cooling Effectiveness of Three Multihole Patterns." Journal of Heat Transfer 128, no. 2 (August 3, 2005): 192–97. http://dx.doi.org/10.1115/1.2137762.
Анотація:
As an advanced cooling scheme to meet increasingly stringent combustor cooling requirements, multihole film cooling has received considerable attention. Experimental data of this cooling scheme are limited in the open literature in terms of different hole patterns and blowing ratios. The heat-mass transfer analogy method was employed to measure adiabatic film cooling effectiveness of three multihole patterns. Three hole patterns differed in streamwise row spacing (S), spanwise hole pitch (P), and hole inclination angle (α), with the first pattern S∕P=2 and α=30°, the second S∕P=1 and α=30°, and the third S∕P=2 and α=150°. Measurements were performed at different blow ratios (M=1-4). Streamwise coolant injection offers high cooling protection for downstream rows. Reverse coolant injection provides superior cooling protection for initial rows. The effect of blowing ratio on cooling effectiveness is small for streamwise injection but significant for reversion injection.
28
Patil, Mahesh, Satyam Panchal, Namwon Kim, and Moo-Yeon Lee. "Cooling Performance Characteristics of 20 Ah Lithium-Ion Pouch Cell with Cold Plates along Both Surfaces." Energies 11, no. 10 (September 25, 2018): 2550. http://dx.doi.org/10.3390/en11102550.
Анотація:
Temperature control of the lithium-ion pouch cells is crucial for smooth operation, longevity and enhanced safety in the battery-operated electric vehicles. Investigating the thermal behavior of lithium-ion pouch cells and optimizing the cooling performance are required to accomplish better performance, long life, and enhanced safety. In the present study, the cooling performance characteristics of 20 Ah lithium-ion pouch cell with cold plates along both surfaces are investigated by varying the inlet coolant mass flow rates and the inlet coolant temperatures. The inlet coolant mass flow rate is varied from 0.000833 kg/s to 0.003333 kg/s, and the inlet coolant temperature is varied from 5 °C to 35 °C. In addition, the effects of the cold plate geometry parameter on cooling performance of 20 Ah lithium-ion pouch cell are studied by varying the number of the channels from 4 to 10. The maximum temperature and difference between the maximum and the minimum temperatures are considered as important criteria for cooling performance evaluation of the 20 Ah lithium-ion pouch cell with cold plates along both surfaces. The cooling energy efficiency parameter (β) and the pressure drop for 20 Ah lithium-ion pouch cell with cold plates along both surfaces are also reported. The study shows that enhanced cooling energy efficiency is accompanied with low inlet coolant temperature, low inlet coolant mass flow rate, and a high number of the cooling channels. As a result, the temperature distribution, the pressure drop, and the cooling energy efficiency parameter (β) of the 20 Ah lithium-ion pouch cell with cold plates along both surfaces are provided, and could be applied for optimizing the cooling performances of the thermal management system for lithium-ion batteries in electric vehicles.
29
Maurya, Rajesh Kumar, M. S. Niranjan, Nagendra Kumar Maurya, and Shashi Prakash Dwivedi. "Development of a System to Control Flow of Coolant in Turning Operation." Journal of Mechanical Engineering 17, no. 1 (April 1, 2020): 17–31. http://dx.doi.org/10.24191/jmeche.v17i1.15216.
Анотація:
Automation of cooling system in machine tools is an effective method for achieving higher productivity and increased tool life. A cooling system is designed to control the operating temperature on the cutting tool tip by circulating coolant through a reservoir built on the top of the machine tool. This arrangement maintains the coolant flow rate as per variation of cutting tool tip temperature sensed by LM-35 temperature sensor which is located 1 cm away (calibrated distance) from the cutting tool tip and whose output voltage is linearly proportional to the temperature. Coolant flow rate is varied in such a manner that the temperature of the cutting tool tip remains within fixed value of temperature. The aim of present work is to develop a cooling control panel system to provide coolant on cutting tool tip in turning operation of mild steel. The coolant flow rate can be increased or decreased as per the variation of sensor temperature during turning of mild steel with high speed steel (HSS) cutting tool at different depth of cut, and spindle speed ,keeping feed rate constant which results in effective cooling of the cutting tool tip. The experiments were carried out with and without use of coolant. It supplies the coolant as per instructions of cooling control panel system which results in saving of coolant as well as power. The mechatronics application of designed cooling control panel system enabled the reduction in cutting tool tip temperature in more robust way as compare to conventional cooling system.
30
Wilfert, Gu¨nter, and Stefan Wolff. "Influence of Internal Flow on Film Cooling Effectiveness." Journal of Turbomachinery 122, no. 2 (February 1, 1999): 327–33. http://dx.doi.org/10.1115/1.555449.
Анотація:
Film cooling experiments were conducted to investigate the effects of internal flow conditions and plenum geometry on the film cooling effectiveness. The film cooling measurements show a strong influence of the coolant inlet conditions on film cooling performance. The present experiments were carried out on a flat plate with a row of cylindrical holes oriented at 30 deg with respect to a constant-velocity external flow, systematically varying the plenum geometry and blowing rates 0.5⩽M⩽1.25. Adiabatic film cooling measurements using the multiple narrow-banded thermochromic liquid crystal technique (TLC) were carried out, simulating a flow parallel to the mainstream flow with and without crossflow at the coolant hole entry compared with a standard plenum configuration. An impingement in front of the cooling hole entry with and without crossflow was also investigated. For all parallel flow configurations, ribs were installed at the top and bottom coolant channel wall. As the hole length-to-diameter ratio has an influence on the film cooling effectiveness, the wall thickness has also been varied. In order to optimize the benefit of the geometry effects with ribs, a vortex generator was designed and tested. Results from these experiments show in a region 5⩽X/D⩽80 downstream of the coolant injection location differences in adiabatic film cooling effectiveness between +5 percent and +65 percent compared with a standard plenum configuration. [S0889-504X(00)01102-8]
31
Zhou, Chuang, Nanjia Yu, Shuwen Wang, Shutao Han, Haojie Gong, Guobiao Cai, and Jue Wang. "The Influence of Thrust Chamber Structure Parameters on Regenerative Cooling Effect with Hydrogen Peroxide as Coolant in Liquid Rocket Engines." Aerospace 10, no. 1 (January 9, 2023): 65. http://dx.doi.org/10.3390/aerospace10010065.
Анотація:
Liquid rocket engines with hydrogen peroxide and kerosene have the advantages of high density specific impulse, high reliability, and no ignition system. At present, the cooling problem of hydrogen peroxide engines, especially with regenerative cooling, has been little explored. In this study, a realizable k-epsilon turbulence model, discrete phase model, eddy dissipation concept model, and 10-step 10-component reaction mechanism of kerosene with oxygen are used. The increased rib height of the regenerative cooling channel causes the inner wall temperature of the engine increases, the average temperature of the coolant outlet decreases slightly, and the coolant pressure decreases. The overall wall temperature decreases as the rib width of the regenerative cooling channel increases. However, in the nozzle throat area, the wall temperature increases, the average coolant outlet temperature decreases, and the coolant pressure drop increases. A decrease in the inner wall thickness of the regenerative cooling channel results in a significant decrease in the wall temperature and a small increase in the average coolant outlet temperature. These findings contribute to the further development of the engine with hydrogen peroxide and can guide the design of its regenerative cooling process.
32
Cabezon, Francisco A., Allan P. Schinckel, Carol S. Stwalley, and Robert M. Stwalley III. "Heat Transfer Properties of Hog Cooling Pad." Transactions of the ASABE 61, no. 5 (2018): 1693–703. http://dx.doi.org/10.13031/trans.12351.
Анотація:
Abstract. Thermal stress on sows in modern farrowing operations has become a significant issue for the commercial pork industry. Purdue University researchers have developed a simple conductive hog cooling pad that has the potential to effectively alleviate a significant portion of that heat stress. The heat transfer properties of the cooling pad are crucial to the characterization of the pad and the success of the pad in the field. This article presents data collected showing the thermal profile of the cooling pad, the energy transfer of the pad in operation, and the effectiveness of the pad as a function of the amount of coolant used to affect heat transfer from a simulated animal to the coolant. A variety of operating conditions and coolant flows were investigated, and those results are detailed in this article. Intermittent coolant flow over modest time intervals appeared to provide the best results with the cooling pad under the investigated operating conditions. Keywords: Conduction, Convection, Cooling, Cooling systems, Farrowing, Heat transfer, Swine, Thermal stress.
33
Choi, Hongseok, Hyoseong Lee, Ukmin Han, Juneyeol Jung, and Hoseong Lee. "Comparative Evaluation of Liquid Cooling-Based Battery Thermal Management Systems: Fin Cooling, PCM Cooling, and Intercell Cooling." International Journal of Energy Research 2024 (April 20, 2024): 1–23. http://dx.doi.org/10.1155/2024/5395508.
Анотація:
The escalating demand for electric vehicles and lithium-ion batteries underscores the critical need for diverse battery thermal management systems (BTMSs) to ensure optimal battery performance. Despite this, a comprehensive comparative analysis remains absent. This study seeks to assess and compare the thermal and hydraulic performances of three prominent BTMSs: fin cooling, intercell cooling, and PCM cooling. Simulation models were meticulously developed and experimentally validated, with each system’s design parameters optimized under identical volumes to ensure equitable comparisons. In the context of fast-charging conditions, intercell cooling consistently met and even surpassed the desired target temperature, reducing the maximum temperature to 30.6°C with an increasing flow rate, while fin cooling faced challenges. Effective control of coolant temperature emerged as a critical factor for achieving optimal PCM cooling, with a potential reduction in temperature difference by 4.3 K. Despite exhibiting higher power consumption, intercell cooling demonstrated the most efficient cooling effect during fast charging. Considering the BTMS weight, fin cooling exhibited the lowest energy density, approximately half that of other methods. Addressing precooling and preheating conditions for high and low temperatures, the intercell method proved adept at meeting temperature requirements with minimal power consumption in significantly shorter durations. Conversely, the practicality of using PCM at high temperatures was deemed challenging.
34
Geurts, Marjolein, Jesper Petersson, Marco Brizzi, Stefan Olsson-Hau, Gert-Jan Luijckx, Ale Algra, Diederik W. J. Dippel, L. Jaap Kappelle, and H. Bart van der Worp. "COOLIST (Cooling for Ischemic Stroke Trial)." Stroke 48, no. 1 (January 2017): 219–21. http://dx.doi.org/10.1161/strokeaha.116.014757.
35
PAGAR., MR SHAILESH J. "DESIGN AND ESTIMATION OF COOLING TOWER." INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, no. 04 (April 23, 2024): 1–5. http://dx.doi.org/10.55041/ijsrem31490.
Анотація:
A cooling tower is a device that rejects waste heat to the atmosphere through the cooling of a coolant stream, usually a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature using radiators. The natural draft cooling tower is an open, direct-contact system. It works using a heat exchanger, allowing hot water from the system to be cooled through direct contact with fresh air. To increase the heat transfer surface area (and optimize the cooling process), hot water is sprayed from nozzles within the tower. Cooling towers in the 19th century through the development of condensers for use with the steam engine. Condensers use relatively cool water, via various means, to condense the steam coming out of the cylinders or turbines. Keywords: Cooling tower, Cooling system, Evaporative cooler, Coolant system.
36
Sirikasemsuk, Sarawut, Songkran Wiriyasart, Ruktai Prurapark, Nittaya Naphon, and Paisarn Naphon. "Water/Nanofluid Pulsating Flow in Thermoelectric Module for Cooling Electric Vehicle Battery Systems." International Journal of Heat and Technology 39, no. 5 (October 31, 2021): 1618–26. http://dx.doi.org/10.18280/ijht.390525.
Анотація:
We investigated the results of the cooling performance of the pulsating water/nanofluids flowing in the thermoelectric cooling module for cooling electric vehicle battery systems. The experimental system was designed and constructed to consider the effects of the water block configuration, hot and cold side flow rates, supplied power input, and coolant types on the cooling performance of the thermoelectric module. The measured results from the present study with the Peltier module are verified against those without the thermoelectric module. Before entering the electric vehicle battering system with a Peltier module, the inlet coolant temperatures were 2.5-3.5℃ lower than those without the thermoelectric system. On the hot side, the maximum COP of the thermoelectric cooling module was 1.10 and 1.30 for water and nanofluids as coolant, respectively. The results obtained from the present approach can be used to optimize the battery cooling technique to operate in an appropriate temperature range for getting higher energy storage, durability, lifecycles, and efficiency.
37
Ye, Ben, Md Rubel, and Hongjun Li. "Design and Optimization of Cooling Plate for Battery Module of an Electric Vehicle." Applied Sciences 9, no. 4 (February 21, 2019): 754. http://dx.doi.org/10.3390/app9040754.
Анотація:
With the development of electric vehicles, much attention has been paid to the thermal management of batteries. The liquid cooling has been increasingly used instead of other cooling methods, such as air cooling and phase change material cooling. In this article, a lithium iron phosphate battery was used to design a standard module including two cooling plates. A single battery numerical model was first created and verified as the basis of the module heat transfer model. Orthogonal experimental design method was adopted in the module thermal model to optimize the main parameters in the module: Battery gap, the cross-section size, and the number of coolant channels of the cooling plate. The Surrogate Model was then utilized to further optimize geometry of the cooling plate. Finally, the optimized geometry was rebuilt in the module thermal model for analysis. The comparison showed that the maximum and minimum temperature difference in the cooling plate was reduced by 9.5% and the pressure drop was reduced by 16.88%. It was found that the battery temperature difference and the pressure drop decreased with the increase of the cross-section and number of the coolant channel when the coolant flow rate was constant at the inlet.
38
Wang, Li Ping, Dong Rong Liu, and Er Jun Guo. "Modeling of Heat Transfer in Spent-Nuclear-Fuel Container during Forced-Chilling Process." Advanced Materials Research 291-294 (July 2011): 2342–51. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.2342.
Анотація:
Application of spheroidal graphite cast iron in the production of spent-nuclear-fuel container contributes to improve the strength and toughness of the casting, because of the nodular shape of graphite. For a large-scale container, a forced-chilling technique is used to accelerate solidification process and raise spheroidization rate. In this paper, modeling of heat transfer in the container is performed. Influences of cooling media, inflow flux of coolant and thickness of sand layer upon the variations of cooling rate are systematically analyzed. Calculated results indicate that water as a coolant is more capable of enhancing the cooling course than air. Increasing inflow flux conducts an effective cooling job, whose influence is more apparent for air-cooling than for water-cooling. The role of decreasing the thickness of sand layer is most pronounced for raising solidification rate. The predicted cooling curves are compared with experimental measurements to validate the model.
39
Wang, Wen, Yan Yan, Yeqi Zhou, and Jiahuan Cui. "Review of Advanced Effusive Cooling for Gas Turbine Blades." Energies 15, no. 22 (November 16, 2022): 8568. http://dx.doi.org/10.3390/en15228568.
Анотація:
Turbine inlet temperature has continuously increased to improve gas turbine performance during the past few decades. Although internal convection cooling and traditional film cooling have contributed significantly to the current achievement, advanced cooling schemes are needed to minimize the coolant consumption and maximize the cooling efficiency for future gas turbines. This paper conducts a comprehensive review of advanced effusive cooling schemes for gas turbine blades. First, the background and the history of turbine blade cooling are introduced. Then, the metrics of effusive cooling efficiency are defined. Next, effusion cooling, impingement/effusion cooling, and transpiration cooling are reviewed. The flow and heat transfer mechanisms of the cooling schemes are emphasized, and the design trends of the cooling schemes are revealed. Finally, the conclusions and future research perspectives are summarized.
40
Li, Xianchang, and Ting Wang. "Simulation of Film Cooling Enhancement With Mist Injection." Journal of Heat Transfer 128, no. 6 (December 9, 2005): 509–19. http://dx.doi.org/10.1115/1.2171695.
Анотація:
Cooling of gas turbine hot-section components, such as combustor liners, combustor transition pieces, and turbine vanes (nozzles) and blades (buckets), is a critical task for improving the life and reliability of them. Conventional cooling techniques using air-film cooling, impingement jet cooling, and turbulators have significantly contributed to cooling enhancements in the past. However, the increased net benefits that can be continuously harnessed by using these conventional cooling techniques seem to be incremental and are about to approach their limit. Therefore, new cooling techniques are essential for surpassing these current limits. This paper investigates the potential of film-cooling enhancement by injecting mist into the coolant. The computational results show that a small amount of injection (2% of the coolant flow rate) can enhance the adiabatic cooling effectiveness about 30–50%. The cooling enhancement takes place more strongly in the downstream region, where the single-phase film cooling becomes less powerful. Three different holes are used in this study including a two-dimensional (2D) slot, a round hole, and a fan-shaped diffusion hole. A comprehensive study is performed on the effect of flue gas temperature, blowing angle, blowing ratio, mist injection rate, and droplet size on the cooling effectiveness with 2D cases. Analysis on droplet history (trajectory and size) is undertaken to interpret the mechanism of droplet dynamics.
41
Madani, Seyed Saeed, Erik Schaltz, and Søren Knudsen Kær. "Design and Simulation of Internal Flowing Twisted Conduits for Cooling of Lithium-Ion Batteries through Thermal Characterization." Batteries 6, no. 2 (May 26, 2020): 31. http://dx.doi.org/10.3390/batteries6020031.
Анотація:
Lithium-ion batteries are extensively used for electric vehicles, owing to their great power and energy density. A battery thermal management system is essential for lithium-ion batteries. With the extensive utilization of liquid-cooling approaches for lithium-ion batteries’ thermal management, temperature homogeneity is considerably influenced by coolant distribution. A lower temperature of the cooling fluid brings about a lower temperature of the cell, but the relation and the amount are important to be analyzed. The cooling efficiency is considerably influenced by the flowing conduit arrangement in the cooling plate. Different parameters are affected by the cooling performance of the battery pack. Consequently, the effect of entrance temperature of coolant fluid, current rate, environment temperature, entrance velocity of the coolant fluid, and plate material on the performance and efficiency of a battery thermal management system were investigated. In this investigation, the program ANSYS/FLUENT was employed as the numerical solver to solve the problem. The simulation was accomplished after the end of the discharge. It was seen that the temperature distributions were the most sensitive to the entrance velocity of coolant fluid. It was concluded that the entrance velocity of coolant fluid has the greatest impact on the cooling efficiency and performance of the cold plate.
42
Bazdidi-Tehrani, F., and G. E. Andrews. "Full-Coverage Discrete Hole Film Cooling: Investigation of the Effect of Variable Density Ratio." Journal of Engineering for Gas Turbines and Power 116, no. 3 (July 1, 1994): 587–96. http://dx.doi.org/10.1115/1.2906860.
Анотація:
Experimental results of the overall and adiabatic cooling effectiveness for full-coverage discrete hole film cooling are presented for a range of practical geometries. The results are reported for various hot gas mainstream-to-coolant temperature (density) ratios, in the realistic range of 1.0–3.2. The variation of this ratio was achieved by increasing the crossflow mainstream temperature, over the range 300–930 K. For combustor wall film cooling applications, the overall cooling effectiveness increased significantly with the number of holes per unit wall surface area, over the range of 4306–26910 m−2 and with the hole size, in the range of 1.0–2.2 mm, due to the improvement in film cooling. The effect of varying the mainstream-to-coolant temperature ratio, in the present range of 1.0–3.2, on the film cooling performance was shown to be small and no consistent trends were established for various configurations, for the coolant mass flow rates per unit wall surface area, less than 0.4 kg/sm2. At a higher value of 0.89 kg/sm2, an increase in the temperature ratio improved the film cooling performance slightly.
43
Lutum, E., and B. V. Johnson. "Influence of the Hole Length-to-Diameter Ratio on Film Cooling With Cylindrical Holes." Journal of Turbomachinery 121, no. 2 (April 1, 1999): 209–16. http://dx.doi.org/10.1115/1.2841303.
Анотація:
Film cooling experiments were conducted to investigate the effects of coolant hole length-to-diameter ratio on the film cooling effectiveness. The results from these experiments offer an explanation for the differences between the film cooling results for cylindrical hole injection configurations previously reported by Goldstein et al. (1974), Pedersen et al. (1977), and Sinha et al. (1991). The previously reported injection configurations differed primarily in coolant hole length-to-diameter ratio. The present experiments were conducted with a row of cylindrical holes oriented at 35 deg to a constant-velocity external flow, systematically varying the hole length-to-diameter ratios (L/D = 1.75, 3.5, 5, 7, and 18), and blowing rates (0.52 ≤ M ≤ 1.56). Results from these experiments show in a region 5 ≤ X/D ≤ 50 downstream of coolant injection that the coolant flow guiding capability in the cylindrical hole was apparently established after five hole diameters and no significant changes in the film cooling effectiveness distribution could be observed for the greater L/D. However, the film cooling effectiveness characteristics generally decreased with decreasing hole L/D ratio in the range of 1.75 ≤ L/D ≤ 5.0. This decrease in film cooling performance was attributed to (1) the undeveloped character of the flow in the coolant channels and (2) the greater effective injection angle of the coolant flow with respect to the external flow direction and surface. The lowest values of film cooling effectiveness were measured for the smallest hole length-to-diameter ratio, L/D = 1.75.
44
Song, Yufei, Zhiguo Liu, Shiwu Li, and Qingyong Jin. "Design and Optimization of an Immersion Liquid Cooling System in Internet Datacenter." International Journal of Heat and Technology 39, no. 6 (December 31, 2021): 1923–29. http://dx.doi.org/10.18280/ijht.390629.
Анотація:
With the development of high-performance chips, the heat flux of Internet datacenter (IDC) is on the rise, and heat dissipation becomes a major bottleneck of IDC development. The cooling needs of the IDC room can hardly be met by the traditional method of air cooling. In recent years, immersion liquid cooling has attracted a growing attention, due to its excellent performance. This paper designs and optimizes an immersion liquid cooling system for IDC. Multiple numerical simulations were carried out to analyze the influence of the system parameters on heat dissipation, and improve the system efficiency using a dielectric coolant. Specifically, 20 graphics processing units (GPUs) and 2 central processing units (CPUs) were set up in each machine of the liquid cooling server. Then, the GPU and CPU temperature was examined under different opening positions on the server top plate, inlet coolant temperatures, and coolant flow speeds. The results show that a 30mm-wide, 430mm-long opening should be set at the upper part of the GPU array, 20mm away from the top plate. The cooling effect can be optimized at the inlet temperature of 30℃, and the coolant flow speed of 3m3/h.
45
van de Noort, Michael, and Peter T. Ireland. "Genetic Algorithm-Based Optimisation of a Double-Wall Effusion Cooling System for a High-Pressure Turbine Nozzle Guide Vane." International Journal of Turbomachinery, Propulsion and Power 9, no. 1 (February 2, 2024): 6. http://dx.doi.org/10.3390/ijtpp9010006.
Анотація:
Double-Wall Effusion Cooling schemes present an opportunity for aeroengine designers to achieve high overall cooling effectiveness and convective cooling efficiency in High-Pressure Turbine blades with reduced coolant usage compared to conventional cooling technologies. This is accomplished by combining impingement, pin-fin and effusion cooling. Optimising these cooling schemes is crucial to ensuring that cooling is achieved sufficiently at high-heat-flux regions and not overused at low-heat-flux ones. Due to the high number of design variables employed in these systems, optimisation through the use of Computational Fluid Dynamics (CFD) simulations can be a computationally costly and time-consuming process. This study makes use of a Low-Order Flow Network Model (LOM), developed, validated and presented previously, which quickly assesses the pressure, temperature, mass flow and heat flow distributions through a Double-Wall Effusion Cooling scheme. Results generated by the LOM are used to rapidly produce an ideal cooling system design through the use of an Evolutionary Genetic Algorithm (GA) optimisation process. The objective is to minimise the coolant mass flow whilst maintaining acceptable metal cooling effectiveness around the external surface of the blade and ensuring that the Backflow Margin for all film holes is above a selected threshold. For comparison, a Genetic Aggregation model-based optimisation using CFD simulations in ANSYS Workbench is also conducted. Results for both the reduction of coolant mass flow and the total optimisation runtime are analysed alongside those from the LOM, demonstrating the benefit of rapid low-order solving techniques.
46
Gritsch, Michael, Achmed Schulz, and Sigmar Wittig. "Effect of Internal Coolant Crossflow on the Effectiveness of Shaped Film-Cooling Holes." Journal of Turbomachinery 125, no. 3 (July 1, 2003): 547–54. http://dx.doi.org/10.1115/1.1580523.
Анотація:
Film-cooling was the subject of numerous studies during the past decades. However, the effect of flow conditions on the entry side of the film-cooling hole on film-cooling performance has surprisingly not received much attention. A stagnant plenum which is widely used in experimental and numerical studies to feed the holes is not necessarily a right means to re-present real engine conditions. For this reason, the present paper reports on an experimental study investigating the effect of a coolant crossflow feeding the holes that is oriented perpendicular to the hot gas flow direction to model a flow situation that is, for instance, of common use in modern turbine blades’ cooling schemes. A comprehensive set of experiments was performed to evaluate the effect of perpendicular coolant supply direction on film-cooling effectiveness over a wide range of blowing ratios (M=0.5…2.0) and coolant crossflow Mach numbers Mac=0…0.6. The coolant-to-hot gas density ratio, however, was kept constant at 1.85 which can be assumed to be representative for typical gas turbine applications. Three different hole geometries, including a cylindrical hole as well as two holes with expanded exits, were considered. Particularly, two-dimensional distributions of local film-cooling effectiveness acquired by means of an infrared camera system were used to give detailed insight into the governing flow phenomena. The results of the present investigation show that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region. Therefore, crossflow at the hole entry side has be taken into account when modeling film-cooling schemes of turbine bladings.
47
Joseph Costello, M. "Cryopreservation of biological specimens." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 492–93. http://dx.doi.org/10.1017/s0424820100148290.
Анотація:
Rapid cooling is the first, critical step in the preservation of biological specimens for examination using a wide variety of electron microscopic techniques. The choice of which cooling method to use depends on many factors, such as the restrictions of specimen geometry, the type of structural information desired and the microscopic techniques to be employed. This summary will highlight some recent technical innovations and novel applications of cryopreservation of biological specimens to study ultrastructure, chemical composition, and dynamic processes.For cryofixation to give realistic preservation of structural details, the specimen must be rapidly brought into intimate contact with the coolant and the contact must be maintained throughout the critical stages of the cooling process. During the last decade, four cooling methods have become prominent because they produce excellent preservation without cryoprotectants, are commercially available and are relatively simple to use: plunge cooling, jet cooling, slam cooling, and high-pressure cooling.Plunge cooling, the most commonly used method for cryofixation, is simply the immersion of a specimen into a liquid coolant usually held near its melting point.
48
Takeishi, Kenichiro, Yutaka Oda, and Yuta Egawa. "B114 Film Cooling with Swirling Coolant Flow Induced by Internal Impingement Jet Cooling." Proceedings of the Thermal Engineering Conference 2011 (2011): 29–30. http://dx.doi.org/10.1299/jsmeted.2011.29.
49
Ye, Bangjiao, Yoshimi Kasugai, Yujiro Ikeda, Yangmei Fan, and Rongdian Han. "Radioactivity Sputtered from Cooling-Pipe Materials into Coolant in the ITER Cooling System." Fusion Science and Technology 40, no. 2 (September 2001): 133–38. http://dx.doi.org/10.13182/fst01-a187.
50
Yan, Shaohang, Mingchen Qiang, Qi Zhao, Yu Hou, and Tianwei Lai. "Research Progress of Enhanced Thermal Evacuation and Cooling Technology for High-Speed Motors." Applied Sciences 14, no. 6 (March 20, 2024): 2617. http://dx.doi.org/10.3390/app14062617.
Анотація:
In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle.