이종 냉각수 활용 3중 열교환기 적용 전동식 냉방시스템 성능 특성 연구

이호성(Hoseong Lee),원종필(Jongphil Won),조중원(Choongwon Cho),임택규(Taekkyu Lim),전한별(Hanbyoel Jeon),남수병(Soobyeong Nam),김동균(Donggyun Kim),김용찬(Yongchan Kim) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5

The objective of this study was to investigate performance characteristics of the triple fluids heat exchanger with different temperature levels of coolants as a condenser in electric-driven air conditioning system. Tested triple fluids heat exchanger to transfer heat between a refrigerant and two kinds of coolants applied to fuel cell electric vehicles, stack coolant with 35% portion and electric device coolant with 65.0% portion of whole area, was developed to use selectively and concurrently coolant sources along with operating conditions due to different temperature levels. In order to analyze performance characteristics of the triple fluids heat exchanger with respect to heat transfer rate and pressure drop, electric-driven air conditioning system with two kinds of coolants was installed and tested under various operating conditions for coolants, such as temperature and volume flow rate. In addition, since developed heat exchanger was used in electric-driven air conditioning system for a fuel cell vehicle, air conditioning system’s performance characteristics with respect to cooling capacity and coefficient of performance (COP) was analyzed after various experiments with inlet air conditions of evaporator and compressor speed. Performance characteristics of tested triple fluids heat exchanger were affected more by the refrigerant flow rate which reflected various air conditioning system operations, such as ambient temperature and compressor speed, than coolant’s. The heat capacity and pressure drop of tested triple fluids heat exchanger with respect to stack coolant operating conditions were about 7.0 ㎾ and 10.0 ㎪ along with stack coolant temperature, respectively. Like stack coolant operating conditions, performance characteristics with the variation of coolants operating conditions was analyzed and optimal operating conditions for coolants was proposed to have better efficiency of tested air conditioning system.

사출성형의 냉각 파라미터가 플라스틱 롤러의 수축에 미치는 영향

조성기,한성렬 한국금형공학회 2021 한국금형공학회지 Vol.15 No.4

A plastic roller for opening and closing the safety door of the injection molding machine was molded. Thedimensional change of the measurement position of the roller was studied when the cooling time was applied differentlyamong the molding conditions, and when the temperature of the coolant applied for mold cooling was also applieddifferently. Cooling times of 300 seconds and 400 seconds, hot and low-temperature coolant were applied. When thelow-temperature coolant was applied, the measuring point of the roller shrank by 0.03 mm. However, when thehigh-temperature coolant was applied, the measuring point shrank by 0.3 mm. It was found that the application oflow-temperature coolant among coolants was more suitable for the reference dimension of the molded article comparedto the application of high-temperature coolant. Among the cooling water applied for the molding of plastic rollers, whenhigh-temperature coolant is applied, the shrinkage rate measured immediately after ejection was smaller than whenlow-temperature coolant is applied. However, it was found that post shrinkage, which occurs over time, occurs muchlarger when high-temperature coolant is applied.

Study on recycling of waste water from spent water-soluble coolant

Kazuya Takada,Yasuo Kondo,Kenji Yamaguchi,Satoshi Sakamoto 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1

We propose a recycling system that can recover the useful water from the spent water soluble coolant by using a surfactant and powdered activated carbon. The processing of about 70 liters of actual spent water soluble coolant yielded about 60 liters of clear water with 6.7 of pH and 0.0 of Brix value. About 120 liters of recycle water-soluble coolant was prepared by diluting an emulsion type cutting fluid 20 times with the recycle water. The recycle coolant has been showing the very similar Brix value and pH changes as those of virgin coolant until 100 days usage. The recycle coolant also showed the same potential to inhibit the progress of flank wear as that of virgin coolant. These facts indicate that the recycled water can be utilized as a dilutor of renewal water-soluble coolant.

The Effect of Coolant Boiling on the Molten Metal Pool Heat Transfer with Local Solidification

Cho, Jea-Seon,Kune Y. Suh,Chung, Chang-Hyun,Park, Rae-Joon,Kim, Sang-Baik Korean Nuclear Society 2000 Nuclear Engineering and Technology Vol.32 No.1

This study is concerned with the experimental test and numerical analysis of the heat transfer and solidification of the molten metal pool with overlying coolant with boiling. In the test, the metal pool is heated from the bottom surface and coolant is injected onto the molten metal pool. Experiments were performed by changing the test section bottom surface temperature of the metal layer and the coolant injection rate. The two-phase boiling coolant experimental results are compared against the dry test data without coolant or solidification of the molten metal pool, and against the crust formation experiment with subcooled coolant. Also, a numerical analysis is performed to check on the measured data. The numerical program is developed using the enthalpy method, the finite volume method and the SIMPLER algorithm. The experimental results of the heat transfer show general agreement with the calculated values. The present empirical test and numerical results of the heat transfer on the molten metal pool are apparently higher than those without coolant boiling. This is probably because this experiment was performed in concurrence of solidification in the molten metal pool and the rapid boiling of the coolant. The other experiments were performed without coolant boiling and the correlation was developed for the pure molten metal without phase change.

Study on the Measurement Accuracy of Coolant Flowrate in a Nuclear Fuel Test Rig

홍진태,김종범,정창영,안성호,양태호,허성호 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.10

To measure the heat generation rate of nuclear fuel rods during an irradiation test, the temperature deviation of the coolant that passes by the fuel rod and its flow velocity need to be measured. Although the temperature of the coolant can be measured by thermocouples instrumented in the nuclear fuel test rig, the flowrate of the coolant is difficult to measure owing to the narrow space of the test rig. Therefore, a noise analysis technique using fluctuation signals from thermocouples installed at both end parts of the fuel rod has been developed by several advanced groups. Although the noise analysis technique was also developed at the Korea Atomic Energy Research Institute, out of pile test results showed that the accuracy of the coolant flow measurement was more than 40%. In this study, the ground pattern of the control board and earth connection are enhanced to eliminate external noise. In addition, a heater unit is installed in the coolant flow simulator to obtain a strong fluctuation signal from the coolant. Thus, the coolant flow simulator is improved, and the accuracy of the coolant flow measurement shows an error of less than 5%.

자동차 엔진 냉각 시스템의 트라이볼로지적인 고장 사례 연구

이일권(Il Kwon Lee),전윤수(Yoon Soo Chun),김청균(Chung Kyun Kim),김도현(Do Hyun Kim),김영규(Young Gyu Kim),김한구(Ran Goo Kim),조승현(Seung Hyun Cho),김승철(Seung Chul Kim) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.11

The purpose of this paper is for study and analysis seeking tribological failure examples produced in cooling system. Considering failure examples originated in the field, it verified for the leakage of coolant giving large damage on vehicle engine because of phenomenon the same as engine corrosion by coolant inflow into combustion chamber, melting of cylinder head exhaust valve part by coolant insufficiency on engine and coolant leakage by cracking of cylinder head camshaft part. It knew that the coolant leakage by radiator tube a crack and plastic part breaking of radiator become cause of failure. It verified the coolant leakage phenomenon by gasket durability a drop of thermostat connecting part with the a-ring and gasket. It verified for the failure example mixed engine oil with coolant that the produced light vibration phenomenon and no acceleration in high-speed driving. The cooling system must thoroughly inspect and manage not to leak the coolant, have the durability of connecting part and mix other materials in coolant.

Enhancing the performance of a long-life modified CANDLE fast reactor by using an enriched ²⁰⁸Pb as coolant

Widiawati, Nina,Su'ud, Zaki,Irwanto, Dwi,Permana, Sidik,Takaki, Naoyuki,Sekimoto, Hiroshi Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.2

The investigation of the utilization of enriched ²⁰⁸Pb as a coolant to enhance the performance of a long-life fast reactor with a Modified CANDLE (Constant Axial shape of Neutron flux, nuclide densities, and power shape During Life of Energy production) burnup scheme has performed. The analyzes were performed on a reactor with thermal power of 800 MegaWatt Thermal (MWTh) with a refueling process every 15 years. Uranium Nitride (enriched ¹⁵N), ²⁰⁸Pb, and High-Cr martensitic steel HT-9 were employed as fuel, coolant, and cladding materials, respectively. One of the Pb-nat isotopes, ²⁰⁸Pb, has the smallest neutron capture cross-section (0.23 mb) among other liquid metal coolants. Furthermore, the neutron-producing cross-section (n, 2n) of ²⁰⁸Pb is larger than sodium (Na). On the other hand, the inelastic scattering energy threshold of ²⁰⁸Pb is the highest among Na, ^natPb, and Bi. The small inelastic scattering cross-section of ²⁰⁸Pb can harden the neutron energy spectrum. Therefore, ²⁰⁸Pb is a better neutron multiplier than any other liquid metal coolant. The excess neutrons cause more production than consumption of ²³⁹Pu. Hence, it can reduce the initial fuel loading of the reactor. The selective photoreaction process was developing to obtain enriched ²⁰⁸Pb. The neutronic was calculated using SRAC and JENDL 4.0 as a nuclear data library. We obtained that the modified CANDLE reactor with enriched ²⁰⁸Pb as coolant and reflector has the highest k-eff among all reactors. Meanwhile, the ^natPb cooled reactor has the lowest k-eff. Thus, the utilization of the enriched ²⁰⁸Pb as the coolant can reduce reactor initial fuel loading. Moreover, the enriched ²⁰⁸Pb-cooled reactor has the smallest power peaking factor among all reactors. Therefore, the enriched ²⁰⁸Pb can enhance the performance of a long-life Modified CANDLE fast reactor.

가스발생기용 추진제에 대한 냉각제 효과

백국현,임유진 한국추진공학회 2005 한국추진공학회지 Vol.9 No.3

The effect of coolants has been studied on the burning properties of low burning rate HTPB/AP composite propellant containing Oxamide or Melamine as coolant for the gas generator. With increasing the content of coolant, the burning rate and the flame temperature could be lowered and the effect on flame temperature was about the same for two coolants. However due to the different thermal decomposition properties of coolant, the burning rate of Melamine propellant was found to abnormally decrease if 200 μm AP was partially replaced with 6 μm AP. 가스발생기용 저 연소속도 HTPB/AP계 고체추진제의 조성에서 냉각제인 Oxamide와 Melamine이 추진제의 연소특성에 미치는 효과를 고찰하였다. 냉각제의 함량을 증가시키면 연소속도와 화염온도가 낮아지고, 두 냉각제의 화염온도에 미치는 영향은 유사하였다. 그러나 냉각제의 열분해 특성 차이로 인하여 Melamine 추진제에서는 비정상적으로 200 μm AP의 일부를 6 μm AP로 대체하면 연소속도가 오히려 감소하는 현상을 나타내었다.

엔진 냉각계의 방열량 해석에 관한 연구(Ⅰ)

원종필,방청세,마상용,박경석 慶熙大學校 1997 論文集 Vol.26 No.-

The higher output levels attained by automotive engines recently been accompanied by an increase in the amount of heat released by the engine. This higher heat release level has caused the thermal load in the engine compartment to rise. As a result, greater emphasis has been placed on thermal analysis of heat radiation from the radiator and of heat release from the engine. Heat release the coolant from the engine is released with heat transfer. It is. thus, the essential element to analysis of heat transfer process in cooling system for an automotive engine. However, most of the research about heat release to the coolant is performed from the standpoint combustion, so this research is done from the standpoint of heat transfer to the cooling system including the engine coolant. This study is performed on the analysis of heat release chracteristics in cooling system for an automotive engine according to the operating and cooling conditions. The results are summarized as follows: 1. The heat release is increased according as coolant temperature is decreased and coolant flowrate is increased. 2. The heat release is increased and heat release per power is decreased according as engine is increased with same engine speed. 3. The heat release is increased by increasing fuel comsumption according as engine speed increased.

ETM 모델을 활용한 이중 순환 냉각의 냉시동시 과도 응답 효과에 관한 연구

강형묵(Hyungmook Kang),김형준(Hyungjun Kim),정대봉(Daebong Jung),안현철(Hyunchul Ahn),민경덕(Kyoungdoug Min) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5

ETM is the research field which has a focus at the effective management of the waste heat of engine. The recent study of ETM which manages the energy flow of engine has interested in the effectual control of coolant system. This paper observes the transient effect of the double loop coolant structure at cold start condition by engine thermal management modeling. The ETM model of this study consists of 6 sub models.: thermal mass model, coolant model, lubricant model, heat transfer model, friction model, and exhaust model. the target engine of ETM model is a 6 cylinder 6.0 L diesel engine. The coolant circuits of head and block are separated; so-called double loop coolant. Each flow rate is adequately controlled by two variable speed water pumps. This structure can make the fast warming up at cold start condition and decrease the loss of water pump works.