AutomotiveThermoelectricDesignIssue

Development and application of an underhood airflow simulation methodologyfor passenger carsJeroen VancoillieSupervisor(s):Sebastian Verhelst,Michel de Paepe,Roger Van WissenAbstract—Simulation has recently been introduced at Toyota Motor Europe to optimize the design of vehicle cooling systems. This abstract describes the developed methodology to solve the airflow through the engine compartment and predict the perfor-mance of the front end heat exchangers by means of CFD.The procedure to build a simulation model is discussed and the se-lection of submodels is motivated.Finally the model’s prediction performance is illustrated by an example result.Keywords—Vehicle cooling,underhood,heat exchanger,CFDI.I NTRODUCTIONV EHICLE cooling requirements are rising.Today’s new vehicles feature high horsepower engines and an underhood compartment crowded with technology to satisfy costumers’expectations regarding performance, safety,comfort and environmental impact.Moreover the shortened development times and high number of powertrain variants are placing additional stress on the designers of cooling systems.The airflow through the front end heat exchangers is critical for the cooling performance of a vehicle.Car manufacturers are taking this into consideration when designing a vehicle.Since many contradicting factors are defining the front end design,a clear understanding of the airflow behavior and its influence on the cooling performance is required.Many have resorted to compu-tationalfluid dynamics(CFD)to get this understanding. The aim of my thesis work was to confirm CFD as a valuable tool for cooling systems’design.In order to serve as a virtual sign-off,the simulation must be able to predict values for critical cooling performance parame-ters,such as engine coolant temperatures.II.S COPE OF THE WORKIn the course of this project we developed a time-and cost-efficient simulation methodology and applied it to a specific vehicle.The vehicle of interest was a Toy-ota Avensis2.2l Diesel with a6-speed automatic trans-mission.The cooling module contains a condenser,full face intercooler,radiator and two fans.A cooling loop for the automatic transmissionfluid(ATF)brings about additional complexity.It consists of an air-to-oil cooler and a little tubular water-to-oil cooler in the radiator out-let tank.III.M ETHODOLOGY AND MODELSFigure1summarizes the procedure to build and val-idate the underhood CFD model.The various steps are treated in more detailbelow.Fig.1.Procedure to build and validate the modelA.Fluid modelingWe selected the CFD software STAR-CCM+to per-form the analysis[1].This program uses thefinite-volume method to numerically solve the Navier-Stokes equations forfluid behavior.Since the Reynolds number forflow around a vehicle is in the range106-107turbulence must be accounted for.Because we are only interested in the influence of turbulence on the meanflow,the realizable k- model was used.A two-layer all y+wall treatment was used,which should provide acceptable near-wall modeling for wall cells in the log-layer,buffer layer and viscous sublayer. The wall treatment is considered accurate enough be-cause we saw theflow is guided more by pressure ef-fects than separation effects.The temperature dependence offluid properties is considered in the model.We found that neglecting this can lead to inaccuracies of more than10%on the pre-dicted airflow rates.putational domain and complex geometryWe combined vehicle CAD data to form an accurate representation of the underhood geometry.Geometri-cal assumptions were minimized by including the entire vehicle exterior in the model.To have a fast process,wrapping technology was used to produce a single,airtight,non-intersecting surfacerepresentation of the vehicle.This is a requisite for the automatic volume mesh creation.Because of limited computational resources we had tofind a trade-off be-tween mesh detail and calculation turnaround time.We used grid refinements only where they are needed the most:at the grill,front end and cooling module.Spe-cial care was taken of low quality grid cells to avoid loss of solution robustness.C.Heat exchanger modelBecause earlier work showed that the heat exchanger and fan representation are critical to the model accuracy [2],we tested the performance of these submodels sep-arately.The heat exchanger core is modeled as a rectangu-lar domain with specified correlations for heat transfer and pressure drop in function of localflow velocity.We calculated these correlations from heat exchanger per-formance data.The model’s accuracy was confirmed by recreating the heat exchanger performance measurements on a vir-tual test rig.The predicted pressure drop and heat rejec-tion were within2%of the measured values.D.Fan modelTo keep the computational cost low,we selected the body force model to represent the fan.The blade ge-ometry is not imported physically,but its contributions to momentum(pressure rise and swirl)are handled with source terms in the Navier-Stokes equations.Earlier work illustrated that this model performs quite well at high fanflow rates[3].The model uses a user-supplied fan curve to calculate the fan operating point and is very dependent on the quality of this fan curve. From simulation results we saw that the fan is actu-ally operating at lowflow rates,where the model per-forms poorly.Also it is currently not clear how the fan curves were obtained.We suspect that the fan model might not be so accurate.In the future more compli-cated fan models might be considered.E.Boundary and operating conditionsAs reported in earlier work[2],we saw that the pre-dicted coolant temperatures are very sensitive to the en-gine heat release.The same is true for heat released to the transmissionfluid.So to have good predictions,ac-curate values are needed for these boundary conditions. We found that in order to get these values,a sound un-derstanding of the engine and torque converter operat-ing point is required.Once these operating points werefixed,we used a 1D simulation model of the coolant loop to predict the coolantflow rate and the engine heat release.For the charge air we used engine maps tofind the theflowrate and intercooler inlet temperature.The heat release to the transmissionfluid was calculated from the torque converter and gearing efficiency.No accurate estimations could be obtained for the transmissionfluidflow rate and the distribution of heat between the air-to-oil and water-to-oil cooler.We con-cluded that the complex hydraulics of the transmission fluid should be considered in a separate1D model.F.SolverTheflow equations were solved in steady state formu-lation.We selected second order discretization to ob-tain good quality results on the complex grid.The solu-tion was considered converged once the scaled residuals had dropped by3to4orders of magnitude and physical values,like coolant temperatures,were stabilized.The full model took1000-2000iterations to converge,which takes about1.5days on an8processor workstation. G.Turnaround timeWith the current methodology an underhood simu-lation model can be built from scratch in about2to3 weeks.Potentially this time can be reduced by automa-tion of the geometry handling and model setup.IV.R ESULTSFigure2shows an example of results obtained with thefinal model.Expectedflow phenomena,like leak-ageflow past the cooling module and recirculation of fan air,are well predicted.The absolute temperature values for coolant and transmissionfluid are in the good range.The remaining errors are mainly caused by in-accurate boundary conditions.The model’s accuracy will be confirmed by wind tunnel measurements,where the boundary conditions can be controlled and are wellknown.Fig.2.Cross-section of the underhood velocityfield:side viewV.C ONCLUSIONWe can conclude that CFD can be used to under-stand theflow phenomena affecting the cooling mod-ule.STAR-CCM+offers sufficient tools to handle the complex underhood geometry and model the heat ex-changer and fan operation.The developed model is able to predict realistic values for the cooling performance parameters and represents the anticipatedflow phenom-ena well.Wind tunnel measurements will be done to confirm the accuracy.Although there is still room for improvement,both on accuracy and turnaround time, the model is already used at Toyota to improve the front end design.R EFERENCES[1]CD-Adapco,STAR-CCM+Version4.02User’s Manual,2009[2] A.Jerhamre&A.J¨o nson,Development and validation of coolanttemperature and cooling airflow CFD simulations at Volvo Cars, SAE-2004-01-0051,2004[3]T.Oshima,ita&M.Yamamoto,Development of predic-tion method for performance of cooling airflow in engine com-partment using computationalfluid dynamics,Mitsubishi Motors Technical Review,volume13,p.42-51,2001。

A M卿麵备蜜全I法规标准I S O/T S1 9880-1:2016气态氢加注站第1部分一般要求标准解读刘再斌管坚石坤段志祥(中国特种设备检测研究院北京100029)摘要：氫燃料电池汽车是目前氫能源交通领域利用的热点，加氫站是为燃料电池汽车加注氢气的场所，是氩能源安全、高效利用的保证，国际标准化组织制定了丨S0 1988〇气态氫加注站系列标准，本文对其第1部 分一般要求的主要内容进行解读，并与国内加氩站相关标准进行对比分析，为我国加氫站相关科学研究和标 准体系建设提供建议。

关键词：加氫站一般要求氫能源氫燃料电池汽车ISO/TS 19880—1:2016 Gaseous Hydrogen Fuelling Stations Part 1 GeneralRequirements Standard InterpretationLiu Zaibin Guan Jian Shi Kun Duan Zhixiang(China Special Equipment Inspection Institute Beijing100029)Abstract Hydrogen fuel cell vehicle is a hot spot in the field of hydrogen energy transportation at present. Hydrogen fuelling station is a place for filling hydrogen into fuel cell vehicle,which is the guarantee of safe and efficient utilization of hydrogen energy.The International Organization for Standardization formulated ISO 19880 gaseous hydrogen fuelling stations series standards,this article interprets the main content of its Part 1general requirements,and compares and analyzes the relevant standards of domestic hydrogen refueling stations,and provides suggestions for scientific research and standard system construction of hydrogen refueling stations in my country.Keywords Hydrogen fuelling station General requirements Hydrogen energy Hydrogen fuel cell vehicles中图分类号：X924 文献标识码：B文章编号：1673-257X(2020)11—0020-04 DOI：10.3969/j. issn.1673-257X.2020.11.005氢能技术能够解决与能源安全、稳定和可持续发 展有关的社会问题，可以推动传统煤炭、石油、天然 气等化石能源清洁利用，支持风能、水能、太阳能等 可再生能源大规模发展，也是全面深入推进绿色交通 发展的最佳选择[u。

第47卷 第14期·60·CHINA RUBBER/PLASTICS TECHNOLOGY AND EQUIPMENT （PLASTICS ）橡塑技术与装备（塑料）在正确的位置，以最精确的方式满足适用于各种部件的复杂要求。

同时，高水平的功能集成旨在使整个装置的组装尽可能容易，这意味着无螺丝装配和最少的组件，以保持低成本。

”（1）在项目中利用专业知识该设计是与充电系统制造商合作讨论的产物，并吸收了朗盛在众多充电基础设施开发项目中已经积累的经验。

Jaschkewitz 说：“这意味着它也满足了许多制造商所表达的愿望，即在涉及到充电口密封时能够尽可能地灵活。

例如，可以使用O 型环、密封绳或系列密封件，也可以采用双组分注塑工艺制造的唇形密封件。

”（2）集成热管理这个充电口设计的关键要素是前后外壳、一个来自充电站的连接器插座和一个执行器。

后者将连接器锁定到位，以防止在充电过程中被意外或故意拉出。

针座是另一个重要的元素。

它将金属连接器的针脚，以及带有用于直流或交流电充电的电缆的印刷电路板（PCB ）等固定到位。

引脚座的设计得到了特别的关注。

它对电缆进行了定位，使充电过程中产生的热量不仅通过它们，而且还通过其他未使用的电缆散去。

Jaschkewitz 说：“这意味着针座支持热管理，从而使大电流下的快速充电更加容易。

”一旦电缆和接触引脚被放置在支架上，印刷电路板被夹住，所有的充电入口部件就会借助卡扣被安装在一起。

电缆在最小的压力下被固定到位，这样它们就不会在外壳中脱落。

Jaschkewitz 说：“在不需要螺丝的情况下连接部件的能力简化了装配过程和相关的物流，这反过来又降低了制造成本。

”（3）满足高材料要求用于充电口的塑料需要符合IEC 62196-1标准，并提供高电绝缘电阻以及高介电强度和抗追踪性。

良好的阻燃性能也是必不可少的。

与带电部件直接接触的部件必须通过符合IEC 60695-2-11标准的辉光线终端产品测试（GWEPT ），辉光线点火温度为850 ℃。

外文文献原稿和译文原稿A New Type Car -- Hybrid Electric VehicleWith skyrocketing fuel prices and changes in weather patterns, many car manufacturers claimed to develop the kind of vehicles that will increase the mileage and reduce the emissions. Hybrid car is a kind of vehicle which can meet above requirements. A hybrid car features a small fuel-efficient gas engine combined with an electric motor that assists the engine.The reasons of building such a complicated machine are twofold: to reduce tailpipe emissions and to improve mileage. Firstly, hybrid cars are good for the environment. They can reduce smog by 90 percent and they use far less gasoline than conventional cars. Meanwhile, hybrid cars burn less gasoline per mile, so they release fewer greenhouse gases. Secondly, hybrid cars are economical. Hybrid cars, which run on gas and electricity, can get up to 55 to 60 miles per gallon in city driving, while a typical SUV might use three times as much gas for the same distance! There are three reasons can mainly account for that: 1) Hybrid engines are much smaller than those on conventional cars. A hybrid car engine is to accommodate the 99% of driving time when a car is not going up hills or accelerating quickly. When extra acceleration power is needed, it relies on the battery to provide additional force. 2) Hybrid gasoline engine can shut off when the car is stopped and run off their electric motor and battery.3) Hybrid cars often recover braking energy. Electric motors could take the lost kinetic energy in braking and use it to charge the battery. Furthermore, hybrids are better than all-electric cars because hybrid car batteries recharge as you drive so there is no need to plug in. Most electric cars need to be recharged every 50-100miles. Also, most electric cars cannot go faster than 50-60 mph, while hybrids can.Hybrid cars bridge the gap between electric and gasoline-powered cars by traveling further and driving faster and hybrid gas-electric cars are proving to be a feasible alternative at a time of high gas prices. So, in my opinion, hybrid cars will have a bright future.How Does Hybrid Electric Vehicle Work？You probably own a gasoline or diesel-engine car. You may have heard of electric vehicles too. A hybrid vehicle or hybrid electric vehicle (HEV) is a combination of both. Hybrid vehicles utilize two or more sources of energy for propulsion. In the case of HEVs, a combustion engine and an electric motor are used.How it works depends on the type of drive train it has. A hybrid vehicle can either have a parallel or series or parallel-series drive train.Parallel HybridThe parallel hybrid car has a gas tank, a combustion engine, transmission,electric motor, and batteries.A parallel hybrid is designed to run directly from either the combustion engine or the electric motor. It can run using both the engine and the motor. As a conventional vehicle, the parallel hybrid draws its power from the combustion engine which will then drive the transmission that turns the wheels. If it is using the electric motor, the car draws its power from the batteries. The energy from the batteries will then power the electric motor that drives the transmission and turns the wheel.Both the combustion engine and the electric motor are used at the same time during quick acceleration, on steep ascend, or when either the engine or the motor needs additional boost.Since the engine is directly connected to the wheels in a parallel drive train, it eliminates the inefficiency of converting mechanical energy into electrical energy and back. This makes a very effective vehicle to drive on the highway.Series HybridThe series hybrid car also has a gas tank, a combustion engine, transmission, electric motor, and batteries with the addition of the generator. The generator can be the electric motor or it can be another separate component.The series configuration is the simplest among the 3. The engine is not connected to the transmission rather it is connected to the electric motor. This means that the transmission can be driven only by the electric motor which draws its energy from the battery pack, the engine or the generator.A hybrid car with a series drive train is more suited for city driving conditions since the engine will not be subjected to the varying speed demands (stop, go, and idle) that contributes to fuel consumption.Series-Parallel HybridThe series-parallel configuration solves the individual problems of the parallel and series hybrid. By combining the 2 designs, the transmission can be directly connected to the engine or can be separated for optimum fuel consumption. The Toyota Prius and the Ford Escape Hybrid use this technology.Honda’s hybridFor those of you who have toyed with the idea of buying a hybrid but were discouraged by the price, you are not alone. In fact, despite the growing concern for the environment, not to mention the skyrocketing price of gas, hybrid cars still only represent a small percentage of global car sales, and a major reason for this is the cost.Hybrids are considered the wave of the future because they not only reduce emissions, addressing the issue of climate change, but they get great gas mileage, an important consideration with the current price of oil. It should be noted that hybrids can also improve the power of the engine, which compromises any advantages in fuel efficiency and emissions. Whatever the application, however, the technology makes the cars more expensive.Because of this, they are the vehicle of choice for only a small niche of people who can afford them, and they currently enjoy a special status amongst the image conscious celebrity-set. For most average consumers, however, they are not an option.That may soon change.Honda Motor Corporation, one of the largest car manufacturers in the world and a leader in fuel efficient technology, has unveiled it’s plan to introduce a low-cost hybrid by 2009. If they can pull it off, they hope to make the hybrid a more mainstream car that will be more appealing to the general public, with the ultimate goal of achieving greater sales and broader appeal than their current incarnation.This, of course, is making Detroit nervous, and may signal a need for American car makers to start making greener and more fuel efficient vehicles, something they could afford to ignore in the past because hybrid cars weren’t worth their attention (due to such a small market share) while gas-guzzling SUVs have such high profit margins.Honda, meanwhile, has had to confront a growing need to compete with Toyota, which has not only grown to be the world’s largest automaker, but makes the car that has become synonymous with the hybrid movement, the Prius. Honda is therefore faced with the seemingly insurmountable task of challenging Toyota’s dominance in the market.Concurrently, Toyota is racing to lower production costs on the Prius, as well, which would hopefully result in a lower cost to the consumer. All eyes are on a potentially favorable car buyers market in 2009.In the meantime, with even adamant global warming naysayers warming up (no pun intended) to the possibilities of an ecological disaster on the horizon, maybe it’s time that we got over our need to drive huge SUVs and start moderating our fuel consumption.Then again, as gas prices hovering around $4.00 and with no ceiling in sight, we may have little choice in the matter.Engine Operating PrinciplesMost automobile dngines are internal combustion, reciprocating 4-stroke gasoline engines, but other types have been used, including the diesel, the rotary ( Wankel ) , the 2-srtoke, and stratified charge.Reciprocating means up and down or banck and forth, It is the up and down action of a piston in the cylinder blick, or engine block. The blick is an iron or aluminum casting that contains engine cylinders and passges called water jackets for coolant circulation. The top of the block is covered with the cylinder head. Which forms the combustion chanber. The bottom of the block is covered with an oil pan or oil sump.Power is produced by the linear motion of a piston in a cylinder. However, this linear motion must be changed into rotary motion to turn the wheels of cars of trucks. The piston is attached to the top of a connecting rod by a pin, called a piston pin or wrist pin. The bottom of the connecting rod is attached to the crankshaft. The connecting rod transmits the up-and-down motion of the piston to the crankshaft, which changes it into rotary motion.The connecting rod is mounted on the crankshaft with large beaings called rodbearings. Similar bearings, called main bearings, are used to mount the crankshaft in the block. Shown in Fig. 1-1The diameter of the cylinder is called the engine bore. Displacement and compression ratio are two frequently used engine specifications. Displacement indicates engine size, and compression ratio compares the total cylinder volume to compression chamber volume.The term stroke is used to describe the movement of the iston within the cylinder, as well as the distance of piston travel. Depending on the type of engine the operating cycle may require either two or four strokes to complete. The 4-stroke engine is also called Otto cycle engine, in honor of the German engineer, Dr. Nikolaus Otto, who first applied the principle in 1876. In the 4-stroke engine, four strokes of the piston in the cylinder are required to complete one full operating cycle. Each stroke is named after the action it performs intake, compression, power, and exhaust in that order, shown in Fig1-2.1、Intake strokeAs the piston moves down, the vaporized mixture of fuel and air enters the cylinder through open intake valve. To obtain the maximum filling of the cylinder the intake valve opens about 10°before t.b.c., giving 20°overlap. The inlet valve remains open until some 50°after b.d.c. to take advantage of incoming mixture.2、 Compression strokeThe piston turns up, the intake valve closes, the mixture is compressed within the combustion chamber, while the pressure rise to about 1Mpa, depending on various factors including the compression ratio, throttle opening and engine speed. Near the top of the stroke the mixture is ignited by a spark which bridges the gap of the spark plug.3、 Power strokeThe expanding gases of combustion produces a rise in pressure of the gas to some 3.5Mpa, and the piston is forced down in the cylinder. The exhaust valve opens near the bottom of the stroke.4、Exhust strokeThe piston moves back up with the exhaust valve open some 50°before b.d.d., allowing the pressure within the cylinder to fall and to reduce ‘back’pressure on the piston during the exhaust stroke, and the burned gases are pushed out to prepare for the next intake stroke.The intake valve usually opens just before the exhaust stroke. This 4-stroke cycle is continuously repeared in every as long as the engineremains running.A 2-stroke engine also goes through four actions to complete one operating cycle.However, the intake and the compression actions are combined in one seroke, and the power and exhaust actions are combined in the other stroke. The term2-stroke cycle or 2-stroke is preferred to the term 2-cycle, which is really not accurate.In automobile engines, all pistons are attached to a single crankshaft. The more cylinders an engine has, the more power strokes produced for cach revolution. This means that an 8-cylinder engine runs more smoothly bdcause the power atrokes arecloser together in time and in degrees of engine rotation.The cylinders of multi-cylinder automotive engines arranged in one of three ways. 1、Inline engines use a single block of cylinder.Most 4-cylinder and any 6-cylinder engines are of this design. The cylinders do not have to be vertical. They can be inclined either side.2、V-type engines use two equal bands of cylinders, usually inclined 60degrees or 90degrees from the cach other. Most V-type engines have 6 or 8 cylinders, although V-4 and V-12 engines have been built.3、Horizontally opposed or pancake engines have two equal banks of cylinders 180degreeas apart. These space saving engine designs are often air-cooled, and are found in the Chevrolet Carvair, Porsches, Subaus, and V olkswagens. Subaus design is liquid cooled.Late-model V olkswagen vans use a liquid-cooled version of the air cooled VWhorizontally opposed engine.译文新型汽车----混合动力汽车在油价飞涨的今天，汽车制造商被要求发展一种排放低，行驶里程长的汽车。