• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.6
• /
• pp.77-88
• /
• 1997

The heat rejection to coolant is a dominant factor for building vehicle cooling system such as radiator and cooling fan. Since the vehicle cooling system also has effects on fuel consumption and noise, the study of heat rejection to coolant has been emphasized. However, the study on heat rejection to coolant has been mainly focused on the field that related to the characteristics of combustion and localized heat loss. It is no much of use in design for the entire cooling system because it is focused on such a specific point. In this work, the heat rejection rate to coolant for four different engines are obtained to derive a simple heat transfer empirical formula that can be applied to the engine cooling system design, and it is compared with the other studies. Also, to observe effects of engine operation factors and heat transfer factors on coolant, we measured the metal temperature and the heat rejection rate. The heat rejection to coolant does not depend significantly upon the coolant flowrate, but mainly upon the amount of air fuel mixture and the air fuel ratio as long as the composition of coolant does not change. The reduction of heat rejection to coolant did not effectively improve the fuel consumption, but was mostly converted to raise the exhaust gas temperature and the oil temperature.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.3
• /
• pp.35-41
• /
• 2001

In recent applications, map controlled thermostat has been adapted to optimize engine cooling system and vehicle cooling system. First of all, this strategy is focused on improving fuel consumption rate and reducing emissions, especially unburned hydrocarbon. The object can be obtained through controlling engine metal temperature by varying engine coolant temperature with engine load and speed. To achieve this goal, it is necessary to understand the characteristics of engine metal temperature and heat rejection rate to coolant. From the results of tested engines, it is obvious that fuel consumption rate has more dominant effect on engine metal temperatures than the corresponding engine power does. Also, Re-Nu relation which shows heat rejection rate to coolant in function of air-fuel mixture and engine specifications has been studied. Also, the empirical Re-Nu relation at full loaded engine was developed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.3
• /
• pp.42-50
• /
• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.5
• /
• pp.3030-3034
• /
• 2015

It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If the performance is poor, engine will be damaged by overheating. But, the development timing of engine is faster than timing of vehicle, it is difficult to test the cooling performance of new engine and vehicle. In this study the powertain cooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted. From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertrain cooling performance was estimated.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.3 s.76
• /
• pp.1-7
• /
• 2007

In this study, the heat balance test of an engine was conducted, and the heat released to coolant is measured and corrected using a power adjustment factor for high fuel temperature to simulate heat rejection of the engine. An engine-converter matching simulation program which can compute the engine speed, transmission output speed, transmission input and output power is developed from the vehicle, transmission and engine performance curve. With this information and the engine heat rejection characteristics, the engine and transmission heat rejection rates can be determined at given condition. In analyzing the air mass flow, a sub program computing the air mass flow rate from the equation of the pressure balance between cooling fan static pressure rise and pressure losses of cooling components is developed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.1-7
• /
• 1999

In this study, the prediction method of coolant flow rates has been developed and applied to an engine and vehicle cooling system. The flow rate passing through each component of the system is very important parameter to evaluate the heat transfer process form the combustion gas to the coolant and the heat rejection process form the radiator /heater to the ambient air. However, the present study reveals that the measurement using the flowmeter fails to give practical flow rates due to its additive resistance. In contrast, the present method which uses the parallel and serial relationship of flow resistance proved to be a good tool to predict the real flow rates. It can be also used to design the cooling system in the incipient stage of engine/vehicle development . The procedure was coded to the computer program so as to use it flexibly and, in the future, to expand it into an independent design tool of the whole cooling system including the heat release and rejection.

• Journal of Energy Engineering
• /
• v.15 no.3 s.47
• /
• pp.160-165
• /
• 2006

Ground source heat pump (GSHP) or geothermal heat pump systems (GHPs) are recognized to be outstanding heating and cooling systems. Most of GSHP systems installed and studied in korea are vertical GSHP systems. A horizontal GSHP system was installed in greenhouse and investigated for the performance characteristics. The results of the study showed that the heating coefficient of performance of the heat pump was 3.64 and the overall heating coefficient of performance of the system was 3.31. The pumping power was obtained as 28.0 W/kW and the required ground heat exchanger length was 53.3 m/kW of rejection heat of condenser. The heat extraction rate was, on average, 14.58 W/m of ground heat exchanger length and trench length is 27.7 m/kW of rejection heat of condenser.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.137-144
• /
• 2005

Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about $60\;{\sim}\;70\%$ and boron rejection rate is about $10\;{\sim}\;20\%$. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is $10kg_{f}/cm^2$, we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about $98\%$, boron rejection rate is about $43\%$. The silica rejection rate of NF270-2540 is about $38\%$, boron rejection rate is about $3.5\%$. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.3
• /
• pp.51-60
• /
• 2002

An analysis method to predict performance of a vehicle cooling system which is composed of radiator, A/C condenser, cooling fan, and etc. is suggested. Air flow through the heat exchanger system and heat rejection rate which dominate the cooling performance are analyzed. Heat transfer with A/C refrigerant phase change is also considered in the analysis. Some predicted results are compared with experimental data for various operating conditions. This evaluation procedure will be useful for the design of optimal vehicle cooling system.

• Membrane Journal
• /
• v.25 no.5
• /
• pp.391-397
• /
• 2015

The porous support polyvinylidene fluoride (PVDF) with a salting out based on the hollow fiber membrane polyethyleneimine (PEI) and polyvinylsulfonic acid (PVSA) by coating with by phase separated and pressurization (PSP) method to produce a multilayer membrane. The resulting membranes were characterized under the various conditions, such as the heat treatment temperature, coating concentration, feed concentration, cross-linking time and cross-link agent concentration in terms of flux and rejection rate for NaCl 100 ppm solution at 4 atm. The best results were PEI 20,000 ppm and PVSA 1,000 ppm, PEI 15% with a 2% malic acid aqueous solution coated by PSP method the hollow fiber membrane heat-treated for 1 minute showed flux 24.3 LMH, the rejection of 82.1%.