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Viewing 121 to 150 of 16480
2017-03-28
Technical Paper
2017-01-1088
Katherine Randall, Cody Bradford, Jeremy Ross, Jeremy Church, Nolan Dickey, Adam Christian, Matthew Dunn
Abstract High frequency variations in crankcase pressure have been observed in Inline-four cylinder (I4) engines and an understanding of the causes, frequency and magnitude of these variations is helpful in the design and effective operation of various engine systems. This paper shows through a review and explanation of the physics related to engine operation followed by comparison to measured vehicle data, the relationship between crankcase volume throughout the engine cycle and the observed pressure fluctuations. It is demonstrated that for a known or proposed engine design, through knowledge of the key engine design parameters, the frequency and amplitude of the cyclic variation in crankcase pressure can be predicted and thus utilized in the design of other engine systems.
2017-03-28
Technical Paper
2017-01-1087
Pengfei Zang, Zhe Wang, Yu Fu, Chenle Sun
Abstract The Linear Internal Combustion Engine-Linear Generator Integrated System (LICELGIS) is different from conventional crank-based engine for reducing frictional losses by eliminating the crankshaft. Thus, the LICELGIS piston stroke is not constrained geometrically and the system compression ratio is variable. During steady-state operation, the LICELGIS converts the fuel chemical energy into electric power with piston assembly reciprocating motion, which can be used as a range-extender in hybrid electric vehicles. The LICELGIS scavenging process is prerequisite and key for the system steady-state operation, which has remarkable influence on mixture gas and, eventually, on engine combustion performance. In order to achieve high scavenging performance, a LICELGIS is investigated in this paper. The LICELGIS motion characteristics and scavenging process were analyzed.
2017-03-28
Journal Article
2017-01-1092
Jianbo Lu, Sanghyun Hong, Jonathan Sullivan, Guopeng Hu, Edward Dai, Dennis Reed, Ryan Baker
Abstract This paper proposes an approach that uses the road preview data to optimize a shift schedule for a vehicle equipped with an automatic transmission. The road preview is inferred here from the so-called electronic horizon of a digital map that includes road attributes such as road grade, curvature, segment speed limit, functional class, etc. The optimized shift schedule selects the gear ratio whose optimization is conducted through applying a hybrid model predictive control method to the powertrain system, which is modelled as the multiple plants associated with multiple gears together with engine models. The goal of this optimization of shift schedule includes improving real world fuel economy and drivability. The real-world fuel economy gains using the proposed approach are achieved through optimizing gear ratio w.r.t. the road grade variations of the road ahead.
2017-03-28
Technical Paper
2017-01-1079
Suresh Kumar Kandreegula, Sayak Mukherjee, Rahul Jain, Shivdayal Prasad, Kamal Rohilla
Abstract Flex Connectors are intended for mitigating the relative movement of exhaust system components along the axis of the system arising from the thermal expansion due to intermittent engine operation. Flex connectors must not be installed in locations, where they will be subjected to destructive vibration. Hence, the stiffness of the flex connector plays an important role, while designing or selecting the right design. It consists of a multi-ply bellows combined with an inside and an outside steel braid. The liner is included to reduce the temperature of the bellows and improve flow conditions. The braid is included for mechanical protection and to limit the possible extension of the joint. It has only axial translational motion.
2017-03-28
Technical Paper
2017-01-1078
Walid Ashraf, Sherif Khedr, Aya Diab, Hashim Elzaabalawy
Abstract A throttle valve is one of the main components of the intake system of a vehicle and is used to control the air flow rate into the combustion chamber at different engine speeds. Consequently, it has considerable effect on the engine power and performance especially at high engine speeds. The butterfly throttle valve is more common in commercial vehicles due to its simplicity. However, the butterfly throttle plate may affect the engine performance by incurring some pumping losses at high engine speeds even with the plate at wide open throttle (WOT) position. Hence it is proposed in this research work to replace and compare the performance of a spark ignition engine butterfly throttle valve to a newly designed barrel-shaped one with regards to the induced air mass flow rate. The main benefit of the proposed barrel-shaped throttle valve is the elimination of the flow restriction at WOT and high engine speeds.
2017-03-28
Technical Paper
2017-01-1077
Nicolas Arnault, Nicolas Batailley, Arnaud Maria, Laurent Bechu
Abstract PSA Group, SOLVAY and SOGEFI have teamed-up to produce the first Plastic Diesel Fuel Filter fully made of recycled polyamide 66, ready for mass-production. This has been achieved by using the brand new plastic compound developed by SOLVAY Engineering Plastics. This material is 100% recycled from airbag wastes, providing a premium material able to stand demanding applications requirements supplied through circular economy, which is quite unusual in automotive industry yet. SOGEFI has used this material through its existing plastic injection process, and tested the parts on extensive bench validation tests. It confirmed that this material is fully compatible with standard injection process, and that all the tests have been passed successfully. Finally, PSA Group has driven the choice of the tested parts: DV engine 1.6l Euro6b application, homologated the material grade and evaluated the whole validation process.
2017-03-28
Technical Paper
2017-01-1085
Todd Brewer, Cagri Sever, Ruichen Jin, Michael Herr, Xingfu Chen, Reda Adimi
Abstract In a separate SAE paper (Cylinder Head Design Process to Improve High Cycle Fatigue Performance), cylinder head high cycle fatigue (HCF) analysis approach and damage calculation method were developed and presented. In this paper, the HCF damage calculation method is used for risk assessment related to customer drive cycles. Cylinder head HCF damage is generated by repeated stress alternation under different engine operation conditions. The cylinder head high cycle fatigue CAE process can be used as a transfer function to translate engine operating conditions to cylinder head damage/life. There are many inputs, noises, and design parameters that contribute to the cylinder head HCF damage CAE transfer function such as cylinder pressure, component temperature, valve seat press fit, and cylinder head manufacturing method. Material properties and the variation in material properties are also important considerations in the CAE transfer function.
2017-03-28
Technical Paper
2017-01-1083
Chawin Chantharasenawong
Abstract This study focuses on achieving a lower overall lap time at SAE Formula Student competition through a modification to the standard intake system. The lower lap time is achieved by widening the range of engine RPM which produces torque higher than 90% of the maximum value and lowering the engine RPM corresponding to the maximum torque. An intake system with ‘variable runner length’ is introduced to the 2015 racecar of KMUTT team. The values of intake lengths are determined from the wave equation with the goal of producing over 90% of the maximum torque of the baseline configuration over a range of engine RPM. Computer simulations are performed to determine the pressure at engine entry at various runner lengths. Finally, a prototype variable runner length intake system with linear motor actuators is constructed and installed on the racecar. Chassis dynamometer tests are performed to determine the engine torque for 3,000 – 10,500 RPM at all interested runner lengths.
2017-03-28
Journal Article
2017-01-1082
Mohammed Yusuf Ali, Thomas Sanders, Mikhail A. Ejakov, Reda Adimi, Alexander Boucke, Jochen Lang, Gunter Knoll
Abstract Strict requirements for fuel economy and emissions are the main drivers for recent automotive engine downsizing and an increase of boosting technologies. For high power density engines, among other design challenges, valve and guide interactions are very important. Undesirable contact interactions may lead to poor fuel economy, engine noise, valve stem to valve guide seizure, and in a severe case, engine failure. In this paper, the valve stem and valve guide contact behavior is investigated using computational models for the camshaft drive in push and pull directions under several misalignment conditions for an engine with roller finger follower (RFF) valvetrain and overhead cam configuration. An engine assembly analysis with the appropriate assembly and thermal boundary conditions are first carried out using the finite element solver ABAQUS.
2017-03-28
Technical Paper
2017-01-1081
Chongzhi Zhong, Tieqiang Fu, Chunbei Dai, Taiyu Zhang, Ke Wu, Wangwen Gu
Abstract In order to study the single cavity and double cavity canister work performance, the L/D, as well as the similarities and differences among the diameter of the adsorption mouth, purge mouth and air mouth have been studied. At the same time, the work performance of ORVR canister and common canister is also studied. The results demonstrate that the similar of L/D, efficient work ability and efficient adsorption rate of the double cavity canister is better than the single cavity canister. The bigger of L/D, the stronger work ability of the canister. However, the excessive increase of the L/D is not conducive to the canister desorption, instead resulting in the increase of RARCP. The adsorption mouth diameter of common canister is generally smaller or similar to the purge mouth, while for ORVR canister the adsorption mouth diameter is bigger than the purge mouth and similar to air mouth.
2017-03-28
Technical Paper
2017-01-1069
Igor Trevas, Adm José baeta, Charles Pimenta, Heder Fernandes, Matheus Carvalho, Raphael Montemor
Abstract Variable Valve Actuation system (VVA) is a technology developed for improving fuel economy, reducing emissions, and enhancing engine performance mainly by reducing pumping losses. Many automakers have used VVA in their engine projects with excellent results. Usually, VVA systems are built to control the valve events in four different ways: changing the amplitude of the valve lift, the valve opening angle, the valve closing angle or a combination of those modes. A special attention at the calibration activity is needed to reach the optimum performance of this system, beyond this, it was necessary to develop a different way to calibrate, much more focused on the development of the combustion and the gas exchange process requiring an intense use of a pressure indicating system. This work presents a comparison between different way of actuation in combustion analysis of a VVA system on a spark ignition engine.
2017-03-28
Technical Paper
2017-01-1076
Mohammad Moetakef, Abdelkrim Zouani, Esra Demren
Abstract In this presentation, two cases of CAE simulations of oil pump-induced tonal noises are presented. The first case involves oil pump-induced whine in an I4engine during coast down. The second case addresses oil pan moan during hot idle and the effect of oil pump pick-up tube positioning inside the oil pan of an I5 engine. The investigations include several design modifications to the pump and the pick-up tube to prevent the tonal noise. Test data are also included to demonstrate the accuracy of the CAE simulation.
2017-03-28
Technical Paper
2017-01-1002
Daisuke Tanaka, Ryo Uchida, Toru Noda, Andreas Kolbeck, Sebastian Henkel, Yannis Hardalupas, Alexander Taylor, Allen Aradi
Abstract The purpose of this work was to gain a fundamental understanding of which fuel property parameters are responsible for particulate emission characteristics, associated with key intermediate behavior in the engine cylinder such as the fuel film and insufficient mixing. Accordingly, engine tests were carried out using various fuels having different volatility and chemical compositions under different coolant temperature conditions. In addition, a fundamental spray and film visualization analysis was also conducted using a constant volume vessel, assuming the engine test conditions. As for the physical effects, the test results showed that a low volatility fuel displayed high particulate number (PN) emissions when the injection timing was advanced. The fundamental test clearly showed that the amount of fuel film on the impingement plate increased under such operating conditions with a low volatility fuel.
2017-03-28
Technical Paper
2017-01-1016
Charles Schenk, Paul Dekraker
Abstract EPA has been benchmarking engines and transmissions to generate inputs for use in its technology assessments supporting the Midterm Evaluation of EPA’s 2017-2025 Light-Duty Vehicle greenhouse gas emissions assessments. As part of an Atkinson cycle engine technology assessment of applications in light-duty vehicles, cooled external exhaust gas recirculation (cEGR) and cylinder deactivation (CDA) were evaluated. The base engine was a production gasoline 2.0L four-cylinder engine with 75 degrees of intake cam phase authority and a 14:1 geometric compression ratio. An open ECU and cEGR hardware were installed on the engine so that the CO2 reduction effectiveness could be evaluated. Additionally, two cylinders were deactivated to determine what CO2 benefits could be achieved. Once a steady state calibration was complete, two-cycle (FTP and HwFET) CO2 reduction estimates were made using fuel weighted operating modes and a full vehicle model (ALPHA) cycle simulation.
2017-03-28
Technical Paper
2017-01-1012
Sunil Kumar Pathak, Vineet sood, Yograj Singh, Salim Abbasbhai Channiwala
Abstract In developing countries like India, large numbers of portable gensets are used as a power source due to the scarcity of grid power supply. The portable gensets, ranging from 0.5 kW to 5 kW are very popular in the residential areas, for example, small restaurants, and shopping complexes, etc. These gensets are using various fuels like gasoline, diesel, LPG, and kerosene in small internal combustion engines. Such engines are the significant source of air pollution, as these are running in the vicinity of populated areas and higher human exposure to these pollutants.Theses gensets are regulated by exhaust and noise emissions norms, set by statutory bodies like the ministry of environment and forest and central pollution control board of India.
2017-03-28
Technical Paper
2017-01-1000
Jong Lee, Yu Zhang, Tom Tzanetakis, Michael Traver, Melanie Moses-DeBusk, John Storey, William Partridge, Michael Lance
Abstract Greenhouse gas regulations and global economic growth are expected to drive a future demand shift towards diesel fuel in the transportation sector. This may create a market opportunity for cost-effective fuels in the light distillate range if they can be burned as efficiently and cleanly as diesel fuel. In this study, the emission performance of a low cetane number, low research octane number naphtha (CN 34, RON 56) was examined on a production 6-cylinder heavy-duty on-highway truck engine and aftertreatment system. Using only production hardware, both the engine-out and tailpipe emissions were examined during the heavy-duty emission testing cycles using naphtha and ultra-low-sulfur diesel (ULSD) fuels. Without any modifications to the hardware and software, the tailpipe emissions were comparable when using either naphtha or ULSD on the heavy duty test cycles.
2017-03-28
Technical Paper
2017-01-0898
Jongwon Lee, Sedoo Oh, Kyung Sub Joo, Seyoung Yi, Kyoung-Pyo Ha, Seongbaek Joo
Abstract The engine indicated torque is not delivered entirely to the wheels, because it is lowered by losses, such as the pumping, mechanical friction and front auxiliary power consumption. The front auxiliary belt drive system is a big power consumer-fueling and operating the various accessory devices, such as air conditioning compressor, electric alternator, and power steering pump. The standard fuel economy test does not consider the auxiliary driving torque when it is activated during the actual driving condition and it is considered a five-cycle correction factor only. Therefore, research on improving the front end auxiliary drive (FEAD) system is still relevant in the immediate future, particularly regarding the air conditioning compressor and the electric alternator. An exertion to minimize the auxiliary loss is much smaller than the sustained effort required to reduce engine friction loss.
2017-03-28
Technical Paper
2017-01-0903
Sarp Mamikoglu, Jelena Andric, Petter Dahlander
Abstract Many technological developments in automobile powertrains have been implemented in order to increase efficiency and comply with emission regulations. Although most of these technologies show promising results in official fuel economy tests, their benefits in real driving conditions and real driving emissions can vary significantly, since driving profiles of many drivers are different than the official driving cycles. Therefore, it is important to assess these technologies under different driving conditions and this paper aims to offer an overall perspective, with a numerical study in simulations. The simulations are carried out on a compact passenger car model with eight powertrain configurations including: a naturally aspirated spark ignition engine, a start-stop system, a downsized engine with a turbocharger, a Miller cycle engine, cylinder deactivation, turbocharged downsized Miller engine, a parallel hybrid electric vehicle powertrain and an electric vehicle powertrain.
2017-03-28
Technical Paper
2017-01-0906
Thomas L. Darlington, Gary A. Herwick, Dennis Kahlbaum, Dean Drake
Abstract The Environmental Protection Agency, National Highway Traffic Safety Administration, and California Air Resources Board released the joint mid-term Technical Assessment Review of the light-duty GHG standards in July of 2016. The review generally asserted that the GHG standards adopted in calendar year 2012 for 2022-2025 model year vehicles were feasible. Although many different technologies were evaluated, the review did not assess the benefits of high compression ratio engines enabled by a high-octane low carbon fuel. This study fills in the gap in the Technical Assessment Review by examining the impacts of a 98-research octane number gasoline-ethanol blend with 25 percent ethanol. We find that this fuel would enable higher compression ratios to improve tailpipe greenhouse gas emissions by about 6 percent on most engines.
2017-03-28
Technical Paper
2017-01-0878
Julia Carrell, Tom Slatter, Uel Little, Roger Lewis
Abstract The interaction of three bio-lubricant base oil candidates with seventeen combinations of surface treatment was studied, comparing wear scar volumes and coefficient of friction results. Substrates were initially ground, then a combination of superfinished, Dymon-iC™ DLC, an impact technique of ultra-fine shot blasting method doped with Tin and Molybdenum Disulfide, a calcium based chemical dip containing calcium sulfate and nano fullerene, were used. DLC is well reported to reduce friction. Some reports suggest wear in coated contacts is independent of the type of lubricant used, whilst others report that bio-lubricants offer reduced friction and wear in combination with DLC. Shot blasting can also reduce wear and friction, due to the surface dimples acting as lubricant reservoirs, making hydrodynamic lubrication more likely.
2017-03-28
Technical Paper
2017-01-0885
Bhuvenesh Tyagi, Vishnu Vijayakumar, Shyam Singh, Ajay Kumar Sehgal, R Suresh
Abstract Majority of light and heavy duty commercial vehicles on road in India use API-CF grade lubricants. Soot accumulation in lubricating oil can result in engine wear and lubricant’s viscosity increase thereby affecting its pumping ability and drain interval. Due to faster lubricant degradation and with emergence of newer engine technologies, there is increasing demand of improving performance of lubricants particularly with respect to soot dispersancy. This paper describes the various engine hardware modifications and optimizations carried out on a commercial BS II, 4-cylinder turbocharged diesel engine in order to develop a flexible engine test procedure for evaluating the lubricant’s dispersancy/anti wear characteristics up to 6% soot levels.
2017-03-28
Technical Paper
2017-01-0886
Liyan Feng, Ximing DI, Wuqiang LONG, Yao Wu, Chao Liu, Hang Lv
Abstract The combustion of cylinder lubricating oil (called as cylinder oil for short) is one of the major sources of PM emissions of low-speed 2-stroke marine diesel engines. For pre-mixed combustion low-speed 2-stroke marine gas engines, the auto-ignition of cylinder oil might result in knock or more hazard abnormal combustion - pre-ignition. Evaporation is a key sub-process of the auto-ignition process of cylinder oil droplets. The evaporation behavior has a profound impact on the auto-ignition and combustion processes of cylinder oil droplets, and a great influence on engine combustion performance and emission characteristics. This paper applied an oil suspending apparatus to investigate the evaporation behavior of cylinder oil droplets and base oil droplets. The effects of ambient temperatures on the evaporation process were measured and analyzed. The results indicate that the evaporation of cylinder oil includes heating, evaporating, pyrolysis, and polymerization.
2017-03-28
Technical Paper
2017-01-0887
Dairene Uy, George Pranis, Anthony Morelli, Arup Gangopadhyay, Alexander Michlberger, Nicholas Secue, Mike Kinzel, Tina Adams, Kevin Streck, Michael Lance, Andrew Wereszczak
Abstract Deposit formation within turbocharger compressor housings can lead to compressor efficiency degradation. This loss of turbo efficiency may degrade fuel economy and increase CO2 and NOx emissions. To understand the role that engine oil composition and formulation play in deposit formation, five different lubricants were run in a fired engine test while monitoring turbocharger compressor efficiency over time. Base stock group, additive package, and viscosity modifier treat rate were varied in the lubricants tested. After each test was completed the turbocharger compressor cover and back plate deposits were characterized. A laboratory oil mist coking rig has also been constructed, which generated deposits having the same characteristics as those from the engine tests. By analyzing results from both lab and engine tests, correlations between deposit characteristics and their effect on compressor efficiency were observed.
2017-03-28
Technical Paper
2017-01-0888
Prashant Kumar, Reji Mathai, Sanjeev KUMAR, Ashish Kachhawa, Ajay Kumar Sehgal, Snigdhamayee Praharaj
Abstract The growing transportation sector worldwide has opened up a way forward not only for the scientists & researchers but also for the OEMs to find out the options for fuel efficient automotive vehicles with reduced emissions during their usage. The demand of automotive vehicles has been doubled in last few years and in turn the market for lubricants and transmission fluids are flourishing. Several new formulations of lubricants are getting popularized with major suppliers to achieve the end user expectations in terms of fuel economy benefits, engine life and emissions. The market trend is continuously moving towards the improvement in lubricant formulation to the lower viscosity ranges and in this direction several companies are into development of multi-grade low viscosity range of engine oils (lubricants) which is said to be providing the benefits in terms of fuel economy.
2017-03-28
Technical Paper
2017-01-0893
Marek Tatur, Kiran Govindswamy, Dean Tomazic
Abstract Demanding CO2 and fuel economy regulations are continuing to pressure the automotive industry into considering innovative powertrain and vehicle-level solutions. Powertrain engineers continue to minimize engine internal friction and transmission parasitic losses with the aim of reducing overall vehicle fuel consumption. Strip friction methods are used to determine and isolate components in engines and transmissions with the highest contribution to friction losses. However, there is relatively little focus on friction optimization of Front-End-Accessory-Drive (FEAD) components such as alternators and Air Conditioning (AC) compressors. This paper expands on the work performed by other researchers’ specifically targeting in-depth understanding of system design and operating strategy.
2017-03-28
Technical Paper
2017-01-0933
Yunhua Zhang, Diming Lou, Piqiang Tan, Zhiyuan Hu, Qian Feng
Abstract Biodiesel as a renewable energy is becoming increasingly attractive due to the growing scarcity of conventional fossil fuels. Meanwhile, the development of after-treatment technologies for the diesel engine brings new insight concerning emissions especially the particulate matter pollutants. In order to study the coupling effects of biodiesel blend and CCRT (Catalyzed Continuously Regeneration Trap) on the particulate matter emissions, the particulate matter emissions from an urban bus with and without CCRT burning BD0 and BD10 respectively was tested and analyzed using electrical low pressure impactor (ELPI). The operation conditions included steady state conditions and transient conditions. Results showed that the particulate number-size distribution of BD10 and BD0 both had two peaks in nuclei mode and accumulation mode at the conditions of idle, low speed and medium speed while at high speed condition the particulate number-size distribution only had one peak.
2017-03-28
Technical Paper
2017-01-1229
Ken Yamamoto, Nobuyasu Sadakata, Hidetoshi Okada, Yusuke Fujita
Abstract Electric oil pumps (EOP) for automobiles are used to lubricate and cool moving parts and supply oil pressure to components. Conventional EOPs consist of two separate units including a motor driver and a pump system comprised of a motor and a pump, which impedes layout flexibility for vehicles. To overcome this shortcoming, we have developed an ECU (electronic control unit)-integrated oil pump in which a driver, a motor and a pump are incorporated as a single unit. In the course of the project, we focused on improving vibration resistance and developing a compact design. The first challenge was to improve vibration resistance because of the driver located in close proximity to the powertrain. Since the driver is installed on the motor unit via electrically welded bus bars, the joints of the driver and the bus bar become susceptible to vibration.
2017-03-28
Technical Paper
2017-01-1175
Ran Bao, Victor Avila, James Baxter
Abstract Recovering as much braking energy as possible, and then fully reusing it, can significantly improve the vehicle powertrain efficiency, hence reducing the CO2 emissions and fuel consumption. A 48 V mild hybrid system recovers less braking kinetic energy than a HV (High Voltage) hybrid system due to the reduced peak power/current rating. However, the cost of the 48 V mild hybrid system is significantly less than the HV hybrid system which gives the 48 V mild hybrid system a much better cost-benefit ratio. The 48 V mild hybrid system can have several different system layouts (e- machines at different positions, or have numerous e-machines at different position combinations). The aim of this study is to investigate and explain how the system layout affects the powertrain system efficiency and CO2 benefit. Simulation models are used to predict the CO2 of three such configurations.
2017-03-28
Technical Paper
2017-01-1189
Tsuyoshi Maruo, Masashi Toida, Tomohiro Ogawa, Yuji Ishikawa, Hiroyuki Imanishi, Nada Mitsuhiro, Yoshihiro Ikogi
Abstract Toyota Motor Corporation (TMC) has been developing fuel cell vehicles (FCVs) since 1992. As part of a demonstration program, TMC launched the FCHV-adv in 2008, which established major technical improvements in key performance areas such as efficiency, driving range, durability, and operation in sub-zero conditions. However, to encourage commercialization and widespread adoption of FCVs, further improvements in performance were required. During sub-zero operating conditions, the FC system output power was lower than under normal operating conditions. The FC stack in the FCHV-adv needed to dry the electrolyte membrane to remove unneeded water from the stack. This increased the stack resistance and caused low output power. In December 2014, TMC launched the world’s first commercially available FCV named the Mirai, which greatly improved output power even after start-up in sub-zero conditions.
2017-03-28
Technical Paper
2017-01-1187
Tatsuya Sugawara, Takuma Kanazawa, Naoki Imai, Yu Tachibana
Abstract This paper describes the motorized turbo compressor, which is a key technology for reducing the size of the fuel cell system for the Clarity Fuel Cell. The oxygen needed for fuel cell power generation is sent into the fuel cell by compressing the air from the atmosphere by a compressor. The conventionally used Lysholm compressor needed numerous sound absorbers, such as silencers and covers, to help achieve quietness when driving. Therefore, changing to a turbo compressor enhanced quietness and helped to eliminate or reduce the size of these auxiliary sound absorbers. Furthermore, a two-stage supercharging structure was used and the air pressure supplied to the fuel cell was increased to 1.7 times the previous air pressure. This increased the fuel cell power, which enabled to reduce the number of cells needed, and reduced the needed humidification amount which enabled to reduce the size of the humidifier. These enhancements helped to reduce the system size.
Viewing 121 to 150 of 16480