• 에너지공학
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• 제19권4호
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• pp.246-250
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• 2010

12 리터급 경유엔진을 개조한 LNG 혼소엔진에 대해 출력, 연비 및 배출가스등의 성능을 평가하였으며 이를 바탕으로 LNG혼소 화물 자동차의 경제성을 분석하였다. 출력은 경유엔진에 비해 5% 정도 낮은 수준으로 평가되었으며 엔진효율은 경유의 경우 37.4%, LNG혼소의 경우 35.9%로 경유엔진의 경우가 다소 높게 나타났다. 배출가스는 탄화수소를 제외하고 PM, NOx, CO 및 $CO_2$는 LNG 혼소의 경우가 낮은 특성을 보였다. 경제성 비교를 위해 연료비용과 환경비용 관점에서 각각 분석하였으며 유가보조금 및 할인을고려할 경우에도 LNG 혼소 화물차의 경제성이 있는 것으로 분석되었다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.841-846
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• 2008

Recently the LNG(liquified natural gas) public buses have been introduced to prevent the air pollution in metropolitan areas. As the LNG temperature in fuel tank is as low as $-162^{\circ}C$. the thermal and structural effects of tank components need to be studied for safe introduction in the market. Especially the support system of LNG fuel tank in vehicle, which has connected with inside and outside of tanks, should put attention to reduce the structural stress due to cryogenic temperature and to restrict the heat flux from ambient. There are two supporting systems in the tank, that one is connected between inside and outside tanks by welding, and the other is the inserted support system which is a cylindrical SUS bar inserted in a hole of the supporting plate. In this study the temperature distribution and thermal stress of the inserted support system were evaluated by using the utility program as ANSYS. The results showed that the rate of heat transfer to inner tank through this support system was quite small due to limited contact of support bar with plate. but the thermal stress of support plate was obtained beyond the limited tensile value of SUS304. The cautious design for the support plate part, therefore, should be given to make the safe support system of LNG vehicle fuel tank.

• Journal of Advanced Marine Engineering and Technology
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• 제30권7호
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• pp.771-781
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• 2006

Car acceleration or deceleration induce the surface slope of liquid fuel in the LNG tank. Slope changes the surface area wetted by liquid fuel in the tank and consequently heat leak to the tank. The Fortran program, 'Pro-Heatleak', is developed to evaluate heat leak on LNG tank. The verification test proves the high accuracy of the developed program. The difference between MathCad and computational results is less than 0.07 %. Computational analyses of heat leak are carried out for 10 gallons and 20 gallons of fuel vapor in the tank. With the increasing of fuel vapor volume by 10 percent the wetted surface area and heat leak respectively decrease by 13 percent. The difference between maximum and minimum heat leak is about 10 percent for both 10 gallons and 20 gallons of fuel vapor in the tank.

• 한국생산제조학회지
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• 제8권3호
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• pp.59-65
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• 1999

To reduce the particulate matter and nitrogen oxides from diesel engine, many studies are proceeding and being accomplished practically. In this situation, LNG engine has important meaning as a clean fuel and alternative energy. In this reason, we try to understand the property of LNG fuel and predict the performance with using LNG engine simulation program and practical test. It could help to lead and apply practically LNG engine was studied in performance and other parameter related with engine performance and compared with current diesel engine. The simulation program was proved to be good in describing the experimental result. This means current heavy duty vehicle could be modified to LNG engine.

• 산업기술연구
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• 제27권B호
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• pp.65-70
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• 2007

The LNG tank are properly designed to fit with the limited installation space of a light duty truck, Hyundai Porter II. This designed LNG tank has 36 liter capacity, so two LNG tanks installed on Porter II truck allow it to run about 432 km per fueling. It is almost two times greater than CNG mileage for same truck. To analyze the relationship between car acceleration and heat leak for different fuel vapor/liquid ratios, the modified Fortran program "Pro-Heatleak" is used. Computational analysis shows that the relationship between the heat leak and vapor/liquid ratio is linearly inversed. Heat leak increases with increasing of car acceleration when fuel vapor/liquid ratio is less than 0.5 and decreases when fuel vapor/liquid ratio is greater than 0.5. The difference between maximum and minimum heat leak for full tank is about 12 percents. For the fuel vapor/liquid ratio equal to 0.5 heat leak does not depend on car acceleration.

• 한국안전학회지
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• 제27권4호
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• pp.76-82
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• 2012

A diesel-Liquefied natural gas(LNG) combustion engine truck fleet demonstration project had been carried out and commercial expansion project was launched. The key issues of these projects are the safety of LNG fuel station and the reduction of natural gas relief. When LNG is fueled to LNG vehicles the heat is input in the LNG system. The LNG in the fueling system was boiled and the vapor of LNG is vented through the safety devices. The temperature of the vapor of LNG is $-108^{\circ}C$ and density is heavier than air. It can be dispersed to downside of the fuel station. The safety evaluation is carried out using CFD program and risk assessment program for the vapor of LNG in the LNG vehicle fuel station. The hazards are identified and suggested the operation instruction to reduce the relief of LNG vapor.

• 산업기술연구
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• 제26권B호
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• pp.11-20
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• 2006

LNG is a valuable fuel since it offers some environmental, energy security and economic benefits over diesel. It could be used mainly in heavy-duty trucks and buses. Car acceleration induces the slope angle of the liquid fuel in the tank. Slope angle changes the surface area wetted by liquid fuel and consequently heat leak to the tank. This research is a result of numerical simulation of the heat leak with the car acceleration to LNG tank. The "Pro-HeatLeak" Fortran program is developed and the verification test of the developed program is done. The difference between numerical results and calculated results from MathCad verification test is less than 0.07 percent. The smallest heat leak is correspond to the case without oscillation. For the high car acceleration the value of heat leak is greater than that for the small acceleration. The difference between maximum and minimum heat leak for 10 gallons of fuel vapor in the tank is about 10 percent.

• 한국분무공학회지
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• 제16권2호
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• pp.97-103
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• 2011

The electronically controlled diesel engine was converted to dual fuel engine system. Test engine was set up for investigating the power output, thermal efficiency and emissions. ND 13-mode tests were employed for the engine test cycle. The emission result of dual fuel mode meets Euro-4 (K2006) regulation and the engine performance of dual fuel engine was comparable to the performance of diesel engine. To estimate economical efficiency, test vehicles have been operated on a certain driving route repeatedly. Fuel economy, maximum driving distance per refueling and driveability were examined on the road including free ways. Developed vehicle can be operated over 500 km with dual fuel mode and shows 80% of diesel substitution ratio. Driveability of dual fuel mode is similar with that of diesel mode.

• Journal of Advanced Marine Engineering and Technology
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• 제32권3호
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• pp.379-386
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• 2008

The 36 liter LNG tank is designed to fit in the limited installation space of a small truck. Two LNG tanks allow one ton truck to run about 432 km per fueling. which is about 1.8 times longer than CNG mileage for the same truck. The variation of BOG with car acceleration for the different fuel liquid/vapor ratios in a tank is analysed by the modified Fortran program "Pro-Heatleak". Computational analyses show that the relationship between the BOG and liquid/vapor ratio is linearly proportional at a given acceleration. Fuel consumption decreases the volume of liquid fuel in the tank but increases the specific BOG. BOG increases with increasing of car acceleration when fuel liquid/vapor ratio is greater than 0.5 and decreases with increasing of car acceleration when fuel liquid/vapor ratio is less than 0.5. The difference between maximum and minimum BOG for full tank is about 12 percents. For the fuel liquid/vapor ratio equal to 0.5 BOG does not depend on car acceleration.

• 한국가스학회지
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• 제19권6호
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• pp.67-71
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• 2015

LNG차량용 초저온 연료탱크의 진동내구성을 검증하기 위해, 고유 진동수를 산출하여 공진여부를 점검하였으며, 진동시험을 수행하였다. 진동시험은 3가지의 양상으로 실시되었는데, 첫째는 초기 가진 주파수를 31.9Hz로 하고, 가진 주파수를 서서히 감소시키면서 시험을 수행하였는데, 가진 주파수가 22.1Hz일 때 파손이 발생하였다. 두 번째는 정지 상태에서 주파수를 증가시키면서 시험을 수행하였는데, 12.7 Hz의 가진 주파수에서 파손이 발생하였고, 질소 가스의 배출이 감지되었다. 세 번째 시험은 가진 주파수를 불규칙하게 연속적으로 변화시키면서 수행하였는데, 가진 주파수가 8 Hz에서 19.3 Hz사이에 있을 때에 진동 포트가 파손되었다. 본 연구에서 감지된 연료탱크의 파손 현상과 진동시험 연구결과가 LNG차량용 초저온 연료탱크의 안전성 제고에 고려되기를 기대한다.