• Proceedings of the SAREK Conference
• /
• 2006.06a
• /
• pp.645-650
• /
• 2006

The heat transfer performance and energy transport ability are relatively high due to higher specific heat. Therefore, it can be used in fields such as heating, ventilating, air-conditioning, refrigeration and heat exchangers. In this study, liquid-cooling heat exchangers were designed and tested by varying geometry and operating conditions. In addition, liquid-cooling heat exchangers were tested to provide performance data for MPCM slurry. The liquid-cooling heat exchangers had twelve rectangular channels with flow paths of 1, 2, 4 and 12. Silicon rubber heaters were used to control the heat load to the heat exchanger. Heat input ranged from 293 to 800 W, and inlet temperatures of working fluid varied from 15S to $27^{\circ}C$. The standard deviation of surface temperature was strongly affected by the coolant of MPCM Slurry, All MPCM-cooling heat exchangers showed higher cooling performance than the water-cooling heat exchanger except one path channel heat exchanger.

• Journal of Power System Engineering
• /
• v.22 no.6
• /
• pp.44-50
• /
• 2018

As a type of bolt with a spherical head, the ball stud is widely used as a part of a ball joint in steering or suspension systems in automobiles. Balls and studs are subjected to heat treatment suitable for each material; in particular, the shear strength of the ball stud must meet the specifications of the production company. This study evaluated the shear strength of joints according to the cooling method of ball studs subject to resistance welding. The shear stress of water cooling was higher than that of air cooling (as-received material). Note, however, th at oil cooling showed lower stress than that of as-received. When judged by standard deviation, mean, and coefficient of variation according to the arithmetic statistics and shape parameter as well as scale parameter, oil cooling is suitable.

• Journal of the Korean Solar Energy Society
• /
• v.29 no.6
• /
• pp.88-93
• /
• 2009

This study was conducted to improve the power of PV module using a surface cooling system One of the unique characteristics of PV module is power drop as a module surface temperature increases due to the characteristics of crystalline silicon used in a solar cell. To overcome the output power reduction by temperature effect, module surface cooling using water circulation was performed. By cooling effect, module surface temperature drops maximally $20.3^{\circ}C$ predicting more than 10% power enhancement. Maximum deviation of voltage and current between a control and cooled module differed by 5.1 V and O.9A respectively. The maximum power enhancement by cooling system was 12.4% compared with a control module. In addition, cooling system can wash the module surface by water circulation so that extra power up of PV module can be achieved by removing particles on the surface which interfere solar radiation on the cells. Cooling system, besides, can reduce the maintenance cost and prevent accidents as a safety precaution while cleaning works. This system can be applied to the existing photovoltaic power generation facilities without any difficulties as well.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.309-313
• /
• 2009

This study was conducted to improve the power of PV module using a surface cooling system. One of the unique characteristics of PV module is power drop as a module surface temperature increases due to the characteristics of crystalline silicon used in a solar cell. To overcome the output power reduction by temperature effect, module surface cooling using water circulation was performed. By cooling effect, module surface temperature drops maximally $20.3^{\circ}C$ predicting more than 10% power enhancement. Maximum deviation of voltage and current between a control and cooled module differed by 5.1V and 0.9A respectively. The maximum power enhancement by cooling system was 12.4% compared with a control module. In addition, cooling system can wash the module surface by water circulation so that extra power up of PV module can be achieved by removing particles on the surface which interfere solar radiation on the cells. Cooling system, besides, can reduce the maintenance cost and prevent accidents as a safety precaution while cleaning works. This system can be applied to the existing photovoltaic power generation facilities without any difficulties as well.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.19 no.1
• /
• pp.83-89
• /
• 2009

Generally, automobile cooling fan is used to lower the temperature of radiator. The cooling fans are manufactured by plastic injection molding process. The center of gravity of cooling fan is often deviated from the center due to the use of deteriorated materials. As the unbalanced of the cooing fan can generate noise, it is required to measure the degree of deviation of center of gravity in the cooling fan. In this work, automatic fan balancer which can effectively detect the magnitude and position of the unbalanced cooling fan is proposed and several experiments are carried out to verify the feasibility of the proposed algorithm.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.3
• /
• pp.179-185
• /
• 2014

Average temperature and temperature uniformity in a battery cell are the important criteria of the thermal management of the battery pack for hybrid electric vehicles and electric vehicles (HEVs and EVs) because high power with large size cell is used for the battery pack. Thus, liquid cooling system is generally applied for the HEV/EV battery pack. The liquid cooling system is made of multiple cooling plates with coolant flow paths. The cooling plates are inserted between the battery cells to reject the heat from batteries to coolant. In this study, the cooling plate with U-shaped coolant flow paths is considered to evaluate the effects of coolant flow condition on the cooling performance of the system. The counter flow and parallel flow set up is compared and the effect of flow rate is evaluated using CFD tool (FLUENT). The number of counter-flows and flow rate are changed and the effect on the cooling performance including average temperature, differential temperature, and standard deviation of temperature are investigated. The results show that the parallel flow has better cooling performance compared with counter flow and it is also found that the coolant flow rate should be chosen with the consideration of trade-off between the cooling performance and pressure drop.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2516-2518
• /
• 2000

In order to reduce the trimming loss for water cooling zone next to finishing block mill in wire rolling, the operational data related to the crop length control of uncooled region was acquired and analyzed. The time deviation of water cooling spray nozzles and the immoderate preset length of uncooled wire rod result in the excessive trimming loss. Therefore, the preset length of uncooled wire rod at each cooling zone are established. The test results of #3 wire rolling mill turned out to be good enough to be expected to increase the ratio of products about 0.15% and establish operational standards of cooling zone.

• Transactions of the Korean hydrogen and new energy society
• /
• v.33 no.4
• /
• pp.451-461
• /
• 2022

CFD analysis including optimization process was conducted to design shell and tube CO₂ methanation reactor cooling system. The high-pressure saturated water flowed into the cooling system and was evaporated by heat flux from reacting tubes. The optimization process decided the gap between tubes and reactor diameter to satisfy objective functions related to temperature. The results showed that the gap and diameter reduced about 30% and 3.6% respectively. Averaged surface temperature satisfied the target value and the min-max deviation was minimized.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.7
• /
• pp.1851-1865
• /
• 1994

The objective of the present study is to predict the film cooling effectiveness by a row of holes at various injection ratios and injection angles. Numerical calculations have been performed to investigate the characteristics of flow and temperature distributions in a region near the down-stream of injection hole including the region of adverse pressure gradient. The elliptic turbulent 3-dimensional governing equations with variable thermal properties using the low-Reynolds number k-$\bar{varepsilon}$ model was solved by SIMPLE algorithm. The results showed that the presence of adverse pressure gradient and secondary vortex in the region near the downstream of injection hole induces large temperature gradent. The $45^{\circ}$ injection has higher averaged film cooling effectiveness than $60^{\circ}$ injection. But neverthless the $90^{\circ}$ injection has greater deviation from a flat plate than $45^{\circ}$ and $60^{\circ}$ injection, the $90^{\circ}$ injection has higher averaged film cooling effectiveness than $45^{\circ}$ and $60^{\circ}$ injection in the region near the downstream of injection hole.

• Acute and Critical Care
• /
• v.33 no.4
• /
• pp.246-251
• /
• 2018

Background: Target temperature management (TTM) improves neurological outcomes for comatose survivors of out-of-hospital cardiac arrest. We compared the efficacy and safety of a gel pad cooling device (GP) and a water blanket (WB) during TTM. Methods: We performed a retrospective analysis in a single hospital, wherein we measured the time to target temperature ($<34^{\circ}C$) after initiation of cooling to evaluate the effectiveness of the cooling method. The temperature farthest from $33^{\circ}C$ was selected every hour during maintenance. Generalized estimation equation analysis was used to compare the absolute temperature differences from $33^{\circ}C$ during the maintenance period. If the selected temperature was not between $32^{\circ}C$ and $34^{\circ}C$, the hour was considered a deviation from the target. We compared the deviation rates during hypothermia maintenance to evaluate the safety of the different methods. Results: A GP was used for 23 patients among of 53 patients, and a WB was used for the remaining. There was no difference in baseline temperature at the start of cooling between the two patient groups (GP, $35.7^{\circ}C$ vs. WB, $35.6^{\circ}C$; P=0.741). The time to target temperature (134.2 minutes vs. 233.4 minutes, P=0.056) was shorter in the GP patient group. Deviation from maintenance temperature (2.0% vs. 23.7%, P<0.001) occurred significantly more frequently in the WB group. The mean absolute temperature difference from $33^{\circ}C$ during the maintenance period was $0.19^{\circ}C$ (95% confidence interval [CI], $0.17^{\circ}C$ to $0.21^{\circ}C$) in the GP group and $0.76^{\circ}C$ (95% CI, $0.71^{\circ}C$ to $0.80^{\circ}C$) in the WB group. GP significantly decreased this difference by $0.59^{\circ}C$ (95% CI, $0.44^{\circ}C$ to $0.75^{\circ}C$; P<0.001). Conclusions: The GP was superior to the WB for strict temperature control during TTM.