쌍발기 대비 A380 연료효율성 비교 분석 연구

장성우,유재림,유광의 한국항공경영학회 2022 한국항공경영학회지 Vol.20 No.3

At the beginning of the operation of the A380, it was expected that the A380 would replace the conventional aircraft with its excellent fuel efficiency and carbon reduction effect. The A380 is efficient when full passenger on board for long-haul routes. However, the commercial aviation landscape has changed dramatically over the past two to three years, and the demand for larger aircraft such as A380 and B747 has disappeared. As oil prices rise, airlines increasingly want to operate high-efficiency aircraft, and manufacturers are developing and supplying twin-engine aircraft such as the A350 and B787, which are capable of longdistance flights and have improved fuel efficiency. As a result of the COVID-19 outbreak, most airlines operating the A380 have suspended the operation of the A380. Currently, the A380 is temporarily operated due to the surge in travel demand. In the long term, the controversy regarding the economic analysis of the A380 operation will continue. In this study, the fuel efficiency of A380 and A350 was comparatively and evaluated. Using actual flight data of A380 and A350, the superiority and inferiority of fuel efficiency were presented with specific figures. Using the fuel efficiency prediction model established in this study, two cases of the same payload and the same load factor were compared. Based on the same payload, the fuel efficiency of the A350 was about 2.0 times higher than that of the A380. Based on the same load factor, the fuel efficiency of the A350 was about 1.35 times higher than that of the A380. Although the difference in fuel efficiency between the two aircraft was reduced, it was confirmed that the fuel efficiency of the latest twin-engine A350 was quite excellent, and it was evaluated that the A380 aircraft had room to compete with the A350 only when close to full passengers were on board. The economics of A380 operation was analyzed by expanding from the technical concept of fuel efficiency to the airline management concept of benefits and costs. However, in order to quantify detailed benefits and costs, there are limitations in that airlines’ own business policies and purchase contracts must be confirmed, and time series predictions of external variables such as crude oil prices and exchange rates must be studied in advance. Exact economic analysis is left as a future study, and in this study, the economic analysis of A380 operation was confirmed at a general level as a result of fuel efficiency comparison. The unit cost excluding fuel cost is assumed to be the same. CASK (Cost per Available Ton Kilometer), which is the cost of flying 1km per passenger, is higher in the A380 than in the A350. On the other hand, the economics of operating the A380 is determined by the RASK (Revenue per Available Ton Kilometer), which is the profit earned when flying 1km per passenger. If the RASK of A380 exceeds 1.35 times that of the A350, the A380 is considered to have a competitive compared with the A350. If the A380’s RASK exceeds the A380’s own CASK, the A380 can continue to operate. Airline must maintain ‘RASK > CASK’ of A380. It is necessary to increase RASK by increasing passenger ticket, cargo transportation, and in-flight duty-free sales, while reducing CASK by reducing cost.

Comparisons of the volumetric efficiency and combustion characteristics between CNG-DI and CNG-PFI engines

Song, Jingeun,Choi, Minhu,Park, Sungwook Elsevier 2017 Applied thermal engineering Vol.121 No.-

<P><B>Abstract</B></P> <P>In the present study, the volumetric efficiency and combustion characteristics of compressed natural gas (CNG) direct injection (DI) and port fuel injection (PFI) were compared. In a single-cylinder engine, various fuel injection timings were tested for each fuel injection position, and the volumetric efficiency of each test condition was calculated from the intake flow rate. The one-dimensional simulation program AMESim was also used to further investigate the intake process. Experimental and numerical results showed that the volumetric efficiency was not influenced by the position of the injector. For the early fuel injection, before the intake valve close (IVC), the volumetric efficiencies of the DI and PFI were similar to each other; the averaged volumetric efficiencies were both about 38.62% and the standard deviations of volumetric efficiency were less than 0.2%. However, as the fuel injection timing was retarded after the IVC, the volumetric efficiency of DI increased while the volumetric efficiency of PFI was kept constant or slightly decreased. The increase in the volumetric efficiency was due to the fact that the fuel volume did not occupy the cylinder volume during the intake stroke. Combustion was stable for all the test conditions. The coefficient of variation of the indicated mean effective pressure (COV<SUB>IMEP</SUB>) was lower than 1.5%. The highest fuel conversion efficiency was observed for late fuel direct injection, after the IVC, due to the fastest combustion. Thus, by applying the late fuel injection timing after IVC, the CNG-DI could have a higher volumetric efficiency and fuel conversion efficiency than the CNG-PFI.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Volumetric efficiencies of DI and PFI were similar for early injection conditions. </LI> <LI> 1D simulation code (AMESim) was used to investigate the intake process in detail. </LI> <LI> For various injection timings, the volumetric efficiency of PFI was kept constant. </LI> <LI> Late fuel DI increased volumetric efficiency and fuel conversion efficiency. </LI> <LI> DI after IVC was the best injection strategy for high engine power and efficiency. </LI> </UL> </P>

공인 연비와 실제 주행 연비 격차에 관한 연구

최선우(Seonwoo Choi),김주환(Juhwan Kim),최회명(Hoimyung Choi) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.3

Drivers have expressed their disappointment with the differences between certified fuel efficiency and real driving fuel efficiency. The extent of the gap between the two types of fuel efficiency has been reported mainly from Europe, so it is necessary to study the gap between the fuel efficiency and certified fuel efficiency of Korean drivers. Therefore, this study recruited Korean drivers and obtained their driving data from the same OBD II terminal. We selected one gasoline vehicle and one diesel vehicle with a large number of drivers and examined the differences among the 4 representative values of the actual fuel efficiency of the driver and the 2016 certified fuel efficiency. The 4 representative values of the actual fuel efficiency of the driver are defined as arithmetic mean, harmonic mean, median value, and mode value according to the statistical method. As a result, certified fuel efficiency is better than the actual fuel efficiency. In the future, we will analyze the gap based on the number of vehicles and different driving conditions.

Operational characteristics of the direct methanol fuel cell stack on fuel and energy efficiency with performance and stability

Park, J.Y.,Seo, Y.,Kang, S.,You, D.,Cho, H.,Na, Y. Pergamon Press ; Elsevier Science Ltd 2012 International journal of hydrogen energy Vol.37 No.7

This paper is presented to investigate operational characteristics of a direct methanol fuel cell (DMFC) stack with regard to fuel and energy efficiency, including its performance and stability under various operating conditions. Fuel efficiency of the DMFC stack is strongly dependent on fuel concentration, working temperature, current density, and anode channel configuration in the bipolar plates and noticeably increases due to the reduced methanol crossover through the membrane, as the current density increases and the methanol concentration, anode channel depth, and temperature decreases. It is, however, revealed that the energy efficiency of the DMFC stack is not always improved with increased fuel efficiency, since the reduced methanol crossover does not always indicate an increase in the power of the DMFC stack. Further, a lower methanol concentration and temperature sacrifice the power and operational stability of the stack with the large difference of cell voltages, even though the stack shows more than 90% of fuel efficiency in this operating condition. The energy efficiency is therefore a more important characteristic to find optimal operating conditions in the DMFC stack than fuel efficiency based on the methanol utilization and crossover, since it considers both fuel efficiency and cell electrical power. These efforts may contribute to commercialization of the highly efficient DMFC system, through reduction of the loss of energy and fuel.

Airline’s Approach to enhance Fuel Efficiency

장성우,유광의,장효석 한국항공경영학회 2018 한국항공경영학회지 Vol.16 No.6

Fuel cost is the one of major cost items, taking up to 30 percent of total operating cost of an airline. Nowadays, Air Transport Industry also needs to address the way of reduction of carbon emission, due to global efforts concerned on responding to climate change. Managing fuel efficiency has become an inevitable task for airlines. This paper will present a new fuel efficiency index to replace the old ones and develop the Fuel Efficiency Prediction Model which will make airlines to improve their everyday fuel efficiency. The model has been developed by using Multiple Regression Analysis with five variables such as payload, air distance, outside air temperature, airplane performance monitoring figure, and aircraft center of gravity. Through the Fuel Efficiency Prediction Model, the influence on fuel efficiency of each variable have been identified and proved. Based on the Model, Airlines get to know how to enhance fuel efficiency logically.

Comparison of fuel efficiency and economical speed for internal combustion engine vehicle and battery electric vehicle using backward-looking simulation

이훈,최회명 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

A vehicle system-level model is developed to predict economical speed and fuel efficiency of an Internal combustion engine vehicle (ICEV) and Battery electric vehicle (BEV) based on a backward-looking simulation approach. The modeled vehicles were chosen within the same commercial model line-up, sharing body panels and most interior and exterior components, to allow more relevant comparison between different powertrains. Numerical methods were applied to representative engine fuel consumption and standard motor efficiency maps in the process of grid construction and fuel efficiency calculation. The economical speed of each vehicle was obtained for constant speed based on fuel efficiency. Combined fuel efficiency was also predicted considering a 5-cycle calibration using the federal test procedure (FTP-75) and Highway fuel economy test (HWFET). It is found that the calculated vehicle economical speed differs between powertrain configurations. Model results were validated against the certified fuel economy of each vehicle model as well as with the on road driving test results. Parametric studies were performed for varying coefficients of drag force and rolling resistance, gear shifting criterion, and vehicle test weight to analyze economical speed characteristics and the effect of advanced vehicle technologies on overall fuel efficiency. It is shown that the BEVs were more suitable than ICEVs, particularly in low speed range situations, such as urban driving condition in terms of fuel efficiency, and were also more effective when fuel efficiency improving technologies reducing driving resistances were applied.

디젤차량 연비시험에 있어 시험온도 및 냉각팬 조건이 미치는 영향분석에 관한 연구

김현진,김성우,임재혁,노경하,이정천,김기호,오상기 한국동력기계공학회 2017 동력시스템공학회지 Vol.21 No.6

Due to the arise of natural disasters caused by global warming, consumers have more interest in the fuel efficiency of their vehicles, and fuel efficiency became an important factor in comparing vehicles. In this market situation, methods to measure fuel efficiency has become one of the main interests of vehicle related organizations and laboratories, and the current method to measure fuel efficiency is to follow the notification established by the ministry of trade, industry and energy, ministry of environment, and the ministry of land, infrastructure and transport. In this study, we analyze the influence of vehicle fuel efficiency according to test temperature and cooling fan condition which have the possibility to cause difference in fuel efficiency. The analysis results of the influence of the fuel efficiency according to the test temperature, the difference of the fuel efficiency of the test temperature (21~29℃) within the allowable range of the notification showed a maximum difference of 2.9%. Therefore, it is necessary to consider the introduction of a test method that permits only the temperature change based on the reference point as the allowable range even in the test within the allowable range. The analysis of the influence of the fuel efficiency according to the cooling method showed no significant effect, and it seems reasonable to maintain the test method of the current notification.

디젤차량 시험온도 조건에 따른 연비 변화 연구

김현진 ( Hyun-jin Kim ),김성우 ( Sung-woo Kim ),임재혁 ( Jae-hyuk Lim ),노경하 ( Kyung-ha Noh ),김기호 ( Ki-ho Kim ) 한국액체미립화학회 2018 한국액체미립화학회 학술강연회 논문집 Vol.2018 No.-

Developed countries are making energy consumption efficiency and CO₂ emission standards by industry average and vehicle grade for rationalizing their energy security and energy use. As natural disasters caused by global warming, consumers have more interest in the fuel efficiency of their vehicles, and fuel efficiency became an important factor in comparing vehicles. In this market situation, methods to measure fuel efficiency has become one of the main interests of vehicle related organizations and laboratories, and the current method to measure fuel efficiency is to follow the notification established by the ministry of trade, industry and energy, ministry of environment, and the ministry of land, infrastructure and transport. In this study, we analyze the influence of vehicle fuel efficiency according to test temperature which has the possibility to cause difference in fuel efficiency. The analysis results of the influence of the fuel efficiency according to the test temperature, the difference of the fuel efficiency of the test temperature within the allowable range of the notification showed a maximum difference of 2.9%. Therefore, it is necessary to consider the introduction of a test method that permits only the temperature change based on the reference point as the allowable range even in the test within the allowable range.

연비 정보의 변화가 소비자의 자동차 구매패턴에 미치는 영향에 관한 실증적 연구

김대욱,김종호 한국경제연구학회 2015 한국경제연구 Vol.33 No.3

In order to provide consumers with definite information on the fuel efficiency of passenger vehicles, in 2008, Korean government unified the standard of fuel efficiency grade regardless of vehicles displacement or types. Using yearly data on 31 vehicle models in Korea from 2003 to 2010, we found that old fuel efficiency grade which depends on vehicles displacement or types has insignificant effect on consumers vehicle choice. In response to the changes in the fuel efficiency grade indication system, however, consumers are more likely to choose vehicles whose fuel efficiency grade is improved after 2008. Our empirical results suggest that unified information on fuel efficiency grade induces consumers more effectively to choose fuel efficient products by providing them with more correct informations on vehicles’ fuel efficiency. 2008년에 정부는 자동차의 용도와 배기량에 따라 차등 적용되었던 자동차 에너지소비효율등급 표시 기준을 연비만을 고려한 단일 기준으로 개편하였다. 기존의 연구에 의하면 연비 정보는 소비자의 자동차 구매선택에 있어서 유의미한 영향을 주는 것으로 알려져 있으며, 결과적으로 이러한 정보의 변화는 소비자의 자동차 구매패턴에 영향을 주었을 가능성이 존재할 것이다. 본 연구는 이러한 효과를 실증적으로 분석하기 위해서 2003년부터 2010년까지 31개 자동차 모델에 대한 연도 자료를 사용하여, 에너지소비효율등급 표시제도가 소비자의 자동차 구매패턴에 미치는 효과를 정량적으로 추정하였다. 분석 결과에 따르면, 2008년 에너지소비효율등급 개정 이후에는 에너지소비효율등급이 상승한 자동차에 대한 수요가 증가한 것으로 분석되었다. 이러한 실증 분석 결과는 정부가 에너지소비효율 개선을 통해서 에너지 소비를 절감시키고 온실가스를 감축시키기 위해서는 소비자에게 에너지 소비효율과 관련된 정보를 보다 명확하게 전달할 필요가 있음을 시사한다.

택시 경영개선을 위한 택시 연료 유종 다양화 방안

홍명호 한국교통연구원 2011 交通硏究 Vol.18 No.4

This research evaluates the fairness of the current taxi fuel policy buses and trucks. Limited in comparison to primary transportation modes, including research on this issue has been conducted thus far. Main transportation system like buses are currently receiving tax benefits to use diesel and CNG fuels. Trucks receive similar benefits to buses. Taxis however do not receive any tax benefits because they use LPG, which is this kind of benefit since LPG that has been used are considered to be the cheapest fuel. The Taegu exhibition recently featured clean diesel taxis with better fuel efficiency with 12㎞/L than LPG taxis (6㎞/L). In addition, the Korean government is involved in various projects of electric cars and hybrids cars under the policy of green growth and environment issues. This paper performs various analyses on the fuel distribution structure, the price system and the tax system of taxi fuel as well as other transportation and environment-friendly fuels. As a result, this research explains reasons for taxi fuel diversification, including improved fuel efficiency, benefits to taxi business, and global environmental issues. 정부는 친환경 및 녹색성장이라는 구호 아래 전기차 및 하이브리드차 등 친화경 차량 구입 시 세제지원 및 관공서 시범사업 등을 적극 추진하고 있음에도 그동안 택시차량의 경우 정부 관계자 및 택시종사자의 대부분은 ‘택시는 곧 LPG 차량’이라고 인식하고 있어 택시 연료의 유종 다양화에 대한 검토나 논의가 전무하였다. 한편, 동일한 운수업종인 버스는 차량 연료로 경유와 CNG를 사용토록 하고 화물 또한 차량 연료로 경유와 LPG를 사용토록 세제지원을 하는 반면에 택시는 소비자의 연료 선택권이 제한되어 있는 등 형평성 문제가 제기되어 왔다. 본 연구는 택시 연료 도입 및 규모, 택시 연료 유통구조 및 가격체계, 국내외 수송용 유류의 세금 및 보조금 그리고 국내외 친환경 연료 실태를 조사 분석하였으며, 택시 연료 경제성 및 환경성과 시범운행 사례를 통하여 유종 다양화 방안을 제시하였다. 대구지역에서 실시한 클린디젤택시 시범사업 결과, 연비 12㎞/L가 넘어 6㎞/L에 불과한 LPG 택시를 압도하였으며, 클린디젤택시 연료에 대한 세금을 전액 면제할 경우 LPG 택시와 비교 시 대당 연간 360만 원(100대 업체 기준 3억 6천만 원) 연료절감 효과가 있어 택시업계 경영개선에 획기적으로 기여할 것으로 예상된다. 택시 연료의 유종 확대와 관련하여 현행 연료 대안으로 제기된 클린디젤차(경유), 하이브리드차(휘발유)가 경제성이 있기 위해서는 LPG 대비 상대적 세금 비중이 큰 휘발유, 경유에 대한 전액 세금 면제가 불가피하며, 아울러 대기오염의 주요인인 CO2 발생은 경유가 휘발유, LPG보다 환경성이 좋은 것으로 나타났다. 해외자료 또한 클린디젤이 휘발유 엔진보다 경제성과 환경성이 우수한 것으로 조사됐다.