• 한국자동차공학회논문집
• /
• 제6권3호
• /
• pp.1-10
• /
• 1998

In this paper, we investigated the improvement of characteristics of knock, emission and fuel consumption rate by optimizing the location and size of water transfer holes in cylinder head gasket without change of engine water jacket design itself. The cooling system was modified in the direction of reducing the metal temperature in the head and increasing the metal temperature in the block. The optimization of water transfer holes in cylinder head gasket was obtained by "flow visualization test". The water transfer holes were concentrated in front side of the engine in order to reduce thermal boundary layer in the water jacket of No. 2 and No. 3 combustion changer in the cylinder head, which would have a large knock intensity, and increase thermal boundary layer in the water jacket of the cylinder block. When the modified coolant flow pattern was applied as proposed in this paper, the knock characteristic was improved. The spark timing was advanced up to 2$^{\circ}$ in low and middle speed range at a full load. In addition, HC emission at MBT was reduced by 5.2%, and the fuel consumption rate was decreased up to 1% in the driving condition of 2400 rpm and 250 KPa. However, since this coolant flow pattern mentioned in this paper might deteriorate the performance of vehicle cooling system due to the coolant flow rate reduction, a properly optimized point should be obtained. obtained.

• 한국기계가공학회지
• /
• 제13권3호
• /
• pp.83-88
• /
• 2014

FSI (Fluid Structure Interaction) method, in this study, has been applied to analyzing thermal characteristics of a high speed machine tool spindle system. The spindle is composed of angular contact ceramic ball bearings, a high speed built-in motor, a cooling jacket, and so on. The cooling jacket has three inlets and outlets. Using the FSI method, temperature distributions and thermal displacements of the spindle system were computed considering the heating of the front and rear bearings and the built-in motor. The results computed using the FSI method were compared with those determined by experiment and using the conventional numerical approach. The results determined using the FSI method were similar to those from the conventional numerical approach but showed better agreement with the experimental results. Therefore, it is concluded that the FSI method is useful for analyzing the thermal characteristics of high speed spindles and can be applied to the design of high speed spindles.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.969-974
• /
• 2002

Thermal characteristics according to the cooling methods are studied for the three type spindles with high frequency motor. For the analysis, three dimensional mode]s are built considering heat transfer characteristics such as natural and force convection coefficients. Unsteady-state temperature distributions and thermal deformations according to the cooling conditions are analyzed by using the finite element method.

• Journal of Advanced Marine Engineering and Technology
• /
• 제40권4호
• /
• pp.282-287
• /
• 2016

최근 조선사들은 선박이 운항되는 연안 환경의 개선과 보호를 위하여 $CO_2$를 절감할 수 있는 친환경 선박과 함께 선박 운항 중 소비하는 에너지의 절감을 위한 고효율화 선박 개발의 노력도 활발하게 수행하고 있다. 본 연구에서는 전기로 구동되는 선박의 증기압축식 냉동기 대신에 선박 엔진 자켓수의 폐열을 이용하여 냉방을 할 수 있는 흡수식 냉동기의 적용 가능성과 냉각시스템에 냉매를 적용하는 시스템의 성능을 분석하였다. 연구결과, 해수와 열교환하여 액화될 수 있는 냉매들 중 R236fa가 가장 적합한 냉매로 분석되었으며, 이를 적용한 흡수식 냉동기의 COP는 0.798로 육상의 냉각탑을 이용한 수랭식보다 15% 그리고 해수 열교환기식 수랭식보다 5% 향상되었다. 냉동능력 1RT를 얻기 위한 LiBr 흡수용액 순환량은 0.013 kg/s로 수랭식 보다 25% 이상 감소하며, 냉각 매체 순환량도 수랭식의 15.7%에 불과한 매우 효과적인 냉동기가 되었다. 해수온도가 $18^{\circ}C$ 이하로 낮으면 발생하게 되는 LiBr의 결정화는 재생기에서 배출되는 엔진 자켓수의 온도를 이용하여 해수 온도를 상승시킴으로써 방지할 수 있다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2009년도 추계학술대회 논문집
• /
• pp.561-562
• /
• 2009

• 한국자동차공학회논문집
• /
• 제1권1호
• /
• pp.32-40
• /
• 1993

Flow fields in model engine cooling passages are studied numerically by using TURBO-3D program, a finite volume based 3-D turbulent flow program adopting a general body fitted coordinate system. The effects of exit position on mass flow rate at each gasket hole are examined for a model cooling passage in order to understand the flow distribution inside the water jacket. The results of the present study can be applied to the design of high performance, high reliability engine.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
• /
• pp.266-266
• /
• 2011

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 춘계학술대회 논문집
• /
• pp.439-444
• /
• 2004

The important problem in high speed spindle is to reduce and minimize the thermal effect by motor and ball bearings. In this study. the effects of bearing preload and cooling for high speed spindle with high frequency motor are investigated. A high speed spindle is composed of angular contact ball bearings, high frequency motor, grease lubrication, oil jacket cooling, and so on. Heat generation of the bearing and the high frequency motor are estimated from the theoretical and experimental data. The thermal analyses of high speed spindle to minimize the thermal effect and maximize the cooling effect are carried out under the various cooling conditions and preload. Method of variable bearing preload and cooling can be useful to design the high speed motor spindle. The results show that the optimal preload and cooling are very effective to minimize the thermal displacement by motor and ball bearing.

• 대한기계학회논문집B
• /
• 제22권8호
• /
• pp.1183-1194
• /
• 1998

This paper describes a theoretical model developed for analyzing the heat transfer of automotive cooling systems. From the model, heat transfer rate of automotive cooling systems can be predicted, providing useful information at the early stages of the design and development. The aim of the study is to develop a simulation program for automotive cooling system analysis and a performance analysis program for analyzing heat exchanger. Heat release rate from combustion gas to coolant through cylinder wall in engine cylinder was analyzed by using a two zone combustion model. This paper studied how cooling condition would affect engine heat release rate and measured temperature distribution of coolant in water jacket.

• 설비공학논문집
• /
• 제26권5호
• /
• pp.224-230
• /
• 2014

The purpose of this paper is to investigate the performance of supplemental cooling and heating system equipped with the 1 kW thermoelectric module. The system consist of 96 thermoelectric modules, heat sink with louver fin and water cooling jacket which is attached on the hot side of the thermoelectric module. The cooling and heating performance test of the thermoelectric system is conducted with various conditions, such as intake voltage, air inlet temperature, air flow volume, water inlet temperature and water flow rate at calorimeter chamber in consideration of environmental conditions in realistic vehicle drive. The experimental results of a thermoelectric system shows that the cooling capacity and COP is 1.03 kW, and 1.0, and heating capacity and COP is 1.53 kW, and 1.5 respectively.