خودروی هیبریدی

خودروی هیبریدی چگونه کار می کند؟

مقدمه امروزه با توجه به آلودگي‌هاي ناشي از خودروها و محدوديت‌هاي سوخت فسيلي، كارخانه‌هاي خودروسازي گام مهمي در مقابله با اين امر برداشته‌اند كه از جمله آنها می توان به خودروهاي هيبریدي (Hybrid Vehicle)، تکنولوژی پيل سوختي (Fuel Cell)، موتورهای با پاشش مستقيم‌ بنزيني (GDI)، موتورهاي HCCI و خودروهاي دو گانه سوز (Bifuel) اشاره کرد. بازدة بالا، آلايندگي كم، مسافت قابل پيمايش بالا، ايمني مطلوب و قيمت قابل رقابت با خودروهاي متداول از جمله ويژگيهاي حائز اهميت براي خودروهاي هيبريدي است. بسياري از خودروسازان بزرگ مبادرت به توليد اين خودروها در سطحی گسترده نموده‌اند. در اين قسمت به شماي كلي از نحوة عملکرد، حالتهاي كاركردي، مزايا، معايب و تقسيم‌بندي سيستم‌هاي مختلف خودروي هيبريدي خواهيم پرداخت. تاريخچة خودروي هيبريدي يك مهندس آمريكائي به نام H.Piper در 23 نوامبر 1905 يك ماشين هيبريدي ساخت كه قادر بود در طي 10 ثانيه تا 25 مايل شتاب بگيرد. موتور اين خودرو تركيبی از موتور بنزيني و موتور الكتريكي بود كه امروزه به عنوان موتور هيبريدي شناخته مي‌شود. Piper در سه سال و نيم بعد، اختراع خود را ثبت نمود؛ اما پيشرفت سريع موتورهای احتراق داخلی با قدرت و گشتاور بالا در آن دوره، همچنين قابليت استارت بدون هندل آنها و از همه مهمتر پايين بودن قيمت سوختهای فسيلی و مطرح نبودن آلودگی محيط زيست، سبب عدم توجه به اين نوع خودروها شد. در پي بحرانهاي نفتي سالهاي 1970 دوباره اين خودروها مورد توجه قرار گرفتند ولي تا سال 1990 که كار اصولي با مشاركت PNGV (Partnership for a New Generation Vehicle) در آمريكا آغاز گرديد، این خودروها به طور جدی پيگيری نشدند. امروزه خودروهاي هيبريدي مورد توجه كمپانيهاي بزرگ جهان قرار گرفته اند كه از آن جمله مي‌توان به شركتهايي مانند: تويوتا، هندا، ميتسوبيشي، فورد، فيات، جنرال موتورز، دايملر كرايسلر، نيسان و پژو و ... اشاره نمود. توفيق اين محصولات به حدي چشمگير بوده كه از دسامبر سال 1997 تا ابتداي سال 2000 بيش از چهل هزار محصول پريوس كمپاني تويوتا به فروش رسيده است. ويژگيها خودروهاي هيبريدي، نوع تعميم يافته خودروهاي برقي خالص مي‌باشند كه معايب خودروهاي برقي خالص تا حدود زيادي در آنها برطرف گرديده است و مي توان گفت معايب خودروهاي احتراق داخلي نيز تا حدودي در آنها برطرف شده است. از مزاياي مهم اين خودروها نسبت به خودروهاي احتراق داخلي، كاركرد در دور و بار ثابت بوده و به اصطلاح در نقطة بهينة خود كار مي‌كنند كه اين امر باعث بالا رفتن بازده موتور و كاهش آلودگي و پايين آمدن مصرف سوخت مي‌گردد و ديگر اينكه به هنگام ترمزگيري و يا شتاب منفي، انرژي به صورت الكتريكي در باطری ها ذخيره مي‌شود و همين امر باعث كاركرد كمتر موتور احتراقي خواهد شد و در نتيجه منجر به كاهش آلودگي و پايين آمدن مصرف سوخت مي‌گردد. به عنوان مثال تويوتا پريوس (Toyota Prius) با موتور ۴ سيلندر ۱۵۰۰ سی سی مصرف سوختی معادل ۲/۴ ليتر در ۱۰۰ کيلومتر دارد. مزيت ديگر اين خودروها نسبت به خودروي برقي خالص، قابليت پيمودن مسيرهاي طولاني در هر بار شارژ كردن باطری مي‌باشد. سيستمهاي ذخيره سازي انرژي : خودروهای هيبريدی از ساختارهاي مختلفي برخوردارند. اما الزاما" يك خودروي هيبريدي از يك سيستم ذخير ساز انرژي، يك واحد توليد قدرت و يك سيستم انتقال قدرت تشكيل شده است. انتخابهاي اوليه براي سيستم ذخيره ساز انرژي باطريها، خازنها و فلايويل‌ها هستند. اگر چه باطريها عمده‌ترين انتخاب در اين زمينه مي‌باشند اما تحقيق بر روي زمينه‌هاي ديگر ذخيره‌سازي انرژي آغاز شده است. باطری ها، بدلیل ارزان و تجاري بودن و نداشتن قسمتهاي متحرک اولين وسيله ذخيره انرژي و همانطور که گفته شد متداولترين است اما بزرگترین عیبشان عمر كوتاه آنها می باشد. البته باطريها با تكنولوژي جديد بسيار گران مي‌باشند و امروزه تعداد زيادي از باطريهاي جديد در حال توسعه هستند. انواع خودروهاي هيبريدي : با توجه به ساختار كنترلي و طريقه اتصال اجزاء به يكديگر، خودروهاي هيبريدي به سه نوع سري، موازي و سری-موازی تقسيم‌بندي مي‌شوند. سيستم هيبريدي سري : در اين دسته از خودروها موتور احتراق داخلي يك ژنراتور را مي‌چرخاند و اين ژنراتور، هم باطري را شارژ می كند و هم يك موتور الكتريكي را به حركت درمي‌آورد و بدین صورت انتقال قدرت صورت می گيرد. در اين ساختار موتور احتراقي مستقيم به سيستم انتقال قدرت وصل نمي‌شود. اين سيستم به خاطر اين سري ناميده مي‌شود كه قدرت، به صورت سري به چرخ‌ها منتقل مي‌گردد و از آن براي رانش موتورهاي با قدرت كم و با رنج كاركرد بهينه استفاده می شود. سيستم هيبريدي موازي : در اين نوع سيستم، موتور احتراقي و موتور الكتريكي به صورت موازي چرخها را به حركت درمي‌آورند. در اين سيستم موتور الكتريكي توسط باطري و موتور احتراقي توسط منبع سوخت فسيلي مستقيما" تغذيه مي‌گردند. در اين حالت ژنراتور حذف شده و باطري با تغيير حالت موتور الكتريكي به ژنراتور شارژ مي‌گردد. از آنجائيكه این سيستم فقط يك موتور دارد موتور الكتريكي نمي‌تواند همزمان هم باطري را شارژ كند و هم باعث رانش چرخها گردد. يك تصوير ساده از اين سيستم در ذيل نشان داده شده است. سيستم هيبريدي سري ـ موازي: اين طرح بگونه ای است كه مي‌توان از آن در شرايط مختلف به صورت هيبريد سري يا موازي استفاده نمود. در اين سيستم با بهره‌گيري از فن‌آوري پيشرفته امكان استفاده از سيستم احتراقي و سيستم الكتريكي بطور جداگانه و همزمان وجود دارد. به اين ترتيب در مواقع شهري كاملا" الكتريكي و بدون آلودگي و در سرعتهاي بالا و در محدودة برون شهري مي‌تواند بطور مستقل احتراقي و يا تركيبي از دو سيستم باشد. در مواقعي چون شتابگيري سريع، هر دو سيستم با هم عمل مي‌كنند. چنين ايده‌اي فقط بكمك يك فن‌آوري مدرن در يك خودرو سواري قابل اجراست. معمولا" چنين سيستمهايي از نوع تركيبي هستند و با بهره‌گيري از يك استراتژي كنترلي مناسب عملا" همراه با فراهم آوردن عملكرد مناسب، سطح شارژ باطريها نيز در حد خوبی نگهداري مي‌شود بدين ترتيب اين خودرو مي‌تواند چه در شهر و چه در جاده به يك خودروي متداول تبديل گردد. در اين سيستم دو موتور الكتريكي وجود دارد كه بسته به شرايط مي‌تواند تركيبي از آنها به كار آيند و قابليت تبديل به ژنراتور را نيز دارند. اين سيستم در خودرو Prius و Estima شرکت تويوتا استفاده شده است. مقايسه چند نوع سيستم هيبريدي: در شكل‌ (1) مقايسه‌اي كلي از سه نوع سيستم هيبريدي صورت گرفته است كه در شكل (2) مي‌توان مزايا و معايب سيستمها را در كنار هم مشاهده نمود. با توجه به جدول فوق می توان خصوصیات زير را برای خودروهای هيبريد سری- موازی برشمرد: ۱- كاهش اتلاف انرژي: سيستم بطور اتوماتيك در حالت idle (درجا) خاموش مي‌شود و بدين ترتيب از به هدر رفتن انرژي جلوگيری می شود. ۲- ذخيره‌سازي و برگرداندن انرژي: انرژيي كه در هنگام شتاب منفي و ترمزگيري هدر مي‌رود را به انرژي الكتريكي تبديل نموده و از اتلاف آنها جلوگيري مي‌كند. ۳- كمك به كاركرد موتور احتراقي: موتور الكتريكي در زمان شتابگيري به كاركرد موتور احتراقي كمك مي‌كند. ۴- كاركرد با بازدهي بالا: اين سيستم با يک استراتژی کنترلی مناسب، بازدهی کلی خودرو را در تمام شرايط کاری در حالت بيشينه نگه می دارد؛ بدين صورت که موتور الکتريکی مانند يک جبران ساز در شرايطی که قدرت موتور احتراق داخلی کافی نيست وارد عمل می گردد و در مواقعی که قدرت موتور احتراق داخلی بيشتر از نياز خودرو است، انرژی مازاد در باطريها ذخيره می گردد. حالتهاي عملكردي موتور هيبريدي سری-موازی: حالتهاي عملكردي يك موتور هيبريدي سری-موازی را مي‌‌توان به شش قسمت تقسيم نمود: حالت روشن شدن و دورهاي پايين و متوسط: در اين حالت موتور احتراقي كه بازدهي مناسبی ندارد كاملا" خاموش است و فقط موتور الكتريكي توان مورد نياز خودرو را تأمين مي‌نمايد (A) حركت در حالتهاي معمولي: قدرت ناشي از موتور احتراقي توسط تقسيم كنندة قدرت (Power split device) به دو بخش تقسيم مي‌گردد قسمتي از قدرت آن به ژنراتور مي‌رود كه منجر به حركت در آوردن موتور الكتريكي مي‌گردد (B) و مابقي چرخها را مستقيما" به حركت درمي‌آورد (C) قدرت موتورا حتراقي در اين مرحله در حداكثر بازدهي است. شتابگيري سريع: در حاليكه قدرت يكنواختي از مسيرهاي B و C به چرخها منتقل می گردد توان اضافي توسط باطري نيز جهت افزايش توان موتور الکتريکی (A) تامين می گردد. شتاب كندشونده و يا ترمزگيري: موتور با قدرت بالا به ژنراتور با قدرت بالايي تبديل مي‌گردد كه توسط چرخها به حركت درمي‌آيد. در اين حالت انرژي جنبشي به انرژي مكانيكي تبديل شده و در باطري ذخيره مي‌گردد. (D) شارژ شدن باطري: براي اينكه باطريها هميشه در حد قابل قبولي انرژي داشته باشند. در حالت ضروري كه احتياج باشد توسط موتور احتراقي شارژ مي‌گردد.(E) حالت استراحت: موتور به حالت اتوماتيك خاموش مي‌گردد.

the road not yet taken

the road not yet taken

To end our dependence on rapidly dwindling oil supplies, switching to hybrid vehicles and ethanol fuel from corn simply isn't enough.

in his State of the Union speech this past January, President George W. Bush declared, "It's in our vital interest to diversify America's energy supply." He then went on to outline what he called "ambitious goals": reducing gasoline consumption by 20 percent in 10 years, boosting use of gasoline alternatives to 35 billion gallons over the same period, and incrementally increasing automobile fuel efficiency standards.

One word that was barely uttered in the speech was hydrogen. It was just a few years ago that hydrogen promised to deliver the clean, fuel-efficient transportation system President Bush has called for. But as knowledgeable scientists and engineers have pointed out, hydrogen is not a fuel source, but merely an energy carrier that must be manufactured. And a "cradle-to-grave"—or, more accurately, a "well-to-wheel"—analysis clearly demonstrates one thing: There is no currently available pathway to produce hydrogen, store it, transport it as an energy carrier, and use it to generate heat or electricity as efficiently as using the heat or electric power from the primary energy source (fossil or nuclear fuels, or sunlight) directly.

Although the current electric grid will have to be strengthened as more electric power is needed, the cost of expanding the existing grid would be much less than building a new hydrogen distribution and storage system from scratch. The cost of building a hydrogen distribution system has been estimated by various sources as costing from 500 billion to one trillion dollars.

These facts are especially relevant to building a secure transportation system for the United States. The U.S. transportation system depends almost entirely on oil. Imports have risen steadily since 1973 as demand increased, and domestic supplies reached a peak and began to decrease. Today, more than 60 percent of the oil consumed in the U.S. is imported, and the dependence on foreign oil, much of it from countries hostile to the United States, is bound to increase. Moreover, oil demand in developing countries, especially China and India, is increasing rapidly just as worldwide production is beginning to approach its peak. Once the world oil peak is reached and oil production begins to drop, the cost of fuel will increase steeply. Unless demand can be curtailed and alternative fuels can be supplied from domestic sources soon, an unprecedented social and economic crisis is likely to ensue.

Replacing the petroleum-based transportation system is of the utmost importance. We have available today options that will enable the development of a transportation system that is more efficient, more secure, and has less negative impact on the environment than the one the United States has currently. Access to petroleum is a problem today. Giving it up will actually be a blessing.

Some energy economists have claimed that there will be no oil supply crisis: Thanks to the so-called magic of the market, as oil becomes more expensive, producers will have incentive to provide more of it. Unfortunately, geology is not subject to the market. Even if the amount of ultimately recoverable oil reserves were to increase from the Energy Information Agency's mean estimate of three trillion barrels to its maximum estimate of four trillion barrels, that only pushes back the peak of production by 11 years. No matter how many places we open up to exploration, production will peak in this generation.

An electric car (top) or plug-in hybrid (above) gets power by plugging into the electrical grid (below).

Unconventional supplies of oil also won't provide relief any time soon. The vast oil-shale deposits in Colorado, Utah, and Wyoming have long been hailed as a future energy source. However, more than half a century of research has not found an economical and environmentally benign way to use oil shale. Therefore, we cannot bank on this resource to help us now. We must instead start to supplement oil as the primary transportation fuel because an orderly transition to develop petroleum substitutes will take time and careful planning.

For instance, turnover in the national automobile fleet is achingly slow. The number of cars that are retired each year, according to statistics compiled by the U.S. Government, can be approximated as a steady 5 percent over 20 years until none remain on the road. The number of new cars added each year can be approximated as 7 percent of the existing fleet. With these rates of turnover and assuming that suddenly all new cars were high-efficiency vehicles, after 10 years 41 percent of all vehicles on the road still would be from the initial low-efficiency fleet, and only after 20 years would essentially all vehicles be high-efficiency. Any realistic scenario would require much longer to convert the fleet to high-efficiency vehicles. To make a large difference in fleet fuel efficiency, then, changes need to be initiated immediately and must be substantial.

Hybrid electric vehicles like the ones on the road today are twice as fuel efficient as the current average vehicle. But the near-term reduction in fuel consumption of hybrid vehicles has been overstated. Even if starting tomorrow half of all new cars and trucks sold in the U.S. were hybrid electric—an absurd proposition—the annual fuel savings in 10 years' time would be less than 15 percent. Even after 20 years, the cumulative savings would be less than one-sixth of what would be otherwise consumed.

Therefore, we need to introduce technologies that use even less petroleum. One technology that can achieve this is the plug-in hybrid electric vehicle. A plug-in hybrid can run moderate distances drawing only on its stored electricity, like a pure electric vehicle, then switch on the engine to extend its range when the battery is drawn down.

The diesel engine is inherently 25 to 30 percent more efficient than the spark-ignition (Otto cycle) engine. Diesel engines are now much cleaner and quieter than they were in the past. In Europe, roughly half of all new vehicles sold are diesel-powered. Furthermore, diesel fuel is more readily produced from coal and biomass than is gasoline. The gasoline engine in hybrid and plug-in hybrid vehicles could just as well be diesel engines to further improve efficiency.

The ultimate gasoline savings that a plug-in hybrid can provide depends on the size of its on-board battery pack, and the driving profile of the vehicle. They can be designed with different all-electric ranges. A PHEV60, a plug-in hybrid electric vehicle that could travel 60 miles on batteries alone, would see a greater number of miles traveled per year in all-electric mode than a PHEV20, with an all-electric range of 20 miles.

According to a study by the Electric Power Research Institute in Palo Alto, Calif., about one-third of the annual mileage for a typical PHEV20 would be electric-powered (EPRI, Technical Report 1009299, May 2004). Given the excellent efficiency of all-electric drivetrains (more than 80 percent, according to recent EPRI data), plug-in hybrids can reach parity with conventional vehicles in terms of life-cycle costs if the price per kilowatt-hour of battery storage were to come down to $316 per kilowatt-hour for a PHEV20 with gasoline at $1.75 a gallon. We have calculated that parity can be reached at a battery cost of about $1,600 per kWh if gasoline costs $2.50 a gallon.

The assumptions made in the EPRI report are very conservative because plug-in hybrid electric vehicles and battery technology are developing rapidly. There are companies, such as Hybrid Prius Inc. and CalCars, that claim PHEV30s can achieve 100 mpg.

One way to obtain liquid fuel from coal is the Fischer-Tropsch process, in which a synthetic gas made from coal is catalyzed. The liquid is similar to petroleum-derived diesel.

Also important is that plug-in hybrid vehicle technology provides utilities with a new and sustainable market for off-peak electric power. According to EPRI, consumer demand for electric power peaks during the day, while more than 40 percent of U.S. generating capacity sits idle or operates at reduced loads overnight. Vehicles could be recharged during these off-peak hours by installing software in the cars that would initiate battery charging only when excess power is available. This arrangement would also even out electricity consumption. Moreover, since no new production facilities or infrastructure would be required, the cost of recharging plug-in hybrids during off-peak hours would be only the extra fuel and operation and maintenance, much less than average utility rates.

High-efficiency vehicles won't solve the gasoline consumption problem alone. Even if every new car from this point forward were a diesel plug-in hybrid or battery electric vehicle, it would take until 2025 at the earliest to achieve a cumulative reduction in gasoline consumption equal to half what an all-gasoline fleet would use. Demand-side solutions are critical, but what is needed is a new way to obtain automotive fuel.

Fortunately, there are options beyond petroleum. Coal, natural gas, and biomass can be transformed chemically into liquid fuels. In the United States, the conversion of coal to liquid fuel has received a great deal of attention of late. The governor of Montana, Brian Schweitzer, as well as senators from Pennsylvania and other political leaders have been promoting the idea as a means of achieving energy independence.

To make coal into a vehicle fuel, it must first be converted to a synthesis gas of hydrogen and carbon monoxide. The sulfur contained in the coal is converted to hydrogen sulfide gas and captured; metals are removed as slag. The gaseous product may then be reacted to one of several chemical products that can be used as vehicle fuel. A big advantage of most liquid fuels is that they can use existing distribution infrastructure with little change, although high concentrations of ethanol require different storage materials.

What's more, the gasification process lends itself to the capture and sequestration of carbon dioxide, with an overall efficiency penalty of about 2 percent. Between the capture of CO₂ at the point of manufacture and the greater efficiency of the plug-in hybrid vehicles, such an integrated system could greatly reduce the nation's greenhouse gas emissions.

The most commonly cited method for turning synthetic gas into liquid fuel is the Fischer-Tropsch process, which was invented by German scientists early in the last century and is used today in South Africa by Sasol to make diesel fuel. The Fischer-Tropsch reaction results in a liquid fuel consisting of approximately 75 percent synthetic diesel and 25 percent naphtha that is used to make synthetic gasoline.

Today, Sasol Ltd., the world's largest maker of motor fuel from coal, produces 160,000 barrels per day in Secunda, South Africa. The 50-year-old plant provides 28 percent of South Africa's supplies of such fuels as diesel, gasoline, and kerosene. Several large liquid-fuel projects are in progress in the Middle East, starting with natural gas that is otherwise flared.

Ramping up production of synthetic fuel won't happen overnight. The estimated time of construction for a plant is four to five years, and the capital investment is large. For example, the capital cost of a coal-gasification Fischer-Tropsch synthesis plant with a capacity to produce 20,000 barrels of liquid fuel per day is estimated to be on the order of $1.2 billion. At present, the U.S. uses something on the order of 20 million barrels of liquid fuel each day.

Opponents of coal gasification claim that there will be excessive greenhouse gas pollution from the process. However, in the future, vehicle fuel-cycle emissions of carbon dioxide can be reduced below those of gasoline-only powered vehicles, by the use of plug-in hybrid electric vehicles and by sequestration of the carbon dioxide from the fuel production process. And coal is far from the only feedstock available for the process. Natural gas can be reacted with steam to make synthetic gas that can be processed in the same way as coal. Indeed, the gas-to-liquid technology is so well developed that four major projects, totaling more than 360,000 barrels a day in production, have been announced in the past two years, including a 32,000 barrel-a-day joint project between Sasol and Qatar Petroleum and a 34,000 barrel-a-day ChevronTexaco facility under construction in Nigeria.

Biomass can be gasified either alone or in combination with coal and converted to liquid fuels by the same process as gasified coal. It can also be pyrolyzed and then processed into vehicle fuels.

Before choosing the direction of synthetic fuels, however, it is important to look at the efficiency of the process. Energy is lost in the conversion of coal, natural gas, or biomass into a vehicle fuel, and the energy efficiency of these conversion processes is important in determining the overall efficiency from well (or mine or farm) to wheel of these alternative pathways.

Ethanol from corn is a rapidly growing vehicle fuel, due largely to a federal subsidy of approximately 50 cents per gallon to the producer. This makes ethanol about the same price per gallon as gasoline, though it is still higher per mile driven. Although there has been controversy about the energy efficiency of ethanol from corn, it has been amply demonstrated that ethanol as currently produced from corn contains 1.25 to 1.3 times more energy than the source energy (not including the solar input to the crop) required to produce it (Farrell, et al., Science, Vol. 311, 506-508, 27 January, 2006, and rael.berkeley.edu/ EBAMM/Farrell).

All fossil fuel-based energy sources produce less energy than is input; gasoline contains only about 0.9 times the energy of the petroleum used to produce it, making it one of the most efficiently produced of fossil fuels. Other issues associated with corn-based ethanol are that corn is part of the food-supply chain, and its use results in a rather small reduction in CO₂ emissions. Ethanol from sugar cane, or from nonfood crops such as switch grass, has a much higher energy output per fossil input than corn, and causes a much larger reduction in CO₂ emissions.

One thing that the experience of the past half-century should teach us is not to rely too heavily on one source of energy for our transportation system. Instead of replacing a petroleum-fueled, internal combustion-powered system with one based entirely on hydrogen or biomass or fuel cells, we should identify the best two or three or four combinations of fuel and vehicle. And we should begin to switch to these new technologies immediately. As we have shown, even a radical change will take time to have a noticeable effect.

Fortunately, there are already several vehicle and fuel technologies available that can help us. Plug-in hybrid electric vehicles, for one, combine the best of both electric vehicles and hybrid technologies. Like electric vehicles, plug-in hybrids can be fueled with electricity generated from domestic sources and produce fewer CO₂ emissions than conventional spark-ignition vehicles do, because of their improved mileage. Like any hybrid, the plug-in variety can run on liquid fuel for acceptable driving range. Because of the reduced fuel
consumption, it may be possible to provide the fuel entirely from domestic sources in the future.

But to ensure that the transition to plug-in hybrids or to some other technology happens rapidly, policy changes must be made. We need a stiff tax on carbon fuels to encourage efficiency, and we need CAFE standards tough enough to prod manufacturers into selling diesel, hybrid, and plug-in hybrid vehicles. Federal programs could spur the development of vehicles with a greater reliance on electric drive and the commercialization of coal- and biomass-based diesel fuel.

There is also a need for immediate research into a number of other related technologies that will be needed in the coming decades. Most importantly, we need to develop processes to produce ethanol from cellulosic material at a reasonable cost and investigate photochemical and high-temperature solar thermal reactions that can produce fuels, including hydrogen. We need to improve the performance of electrical storage in batteries or ultracapacitors. And we must develop technologies that can capture and store carbon dioxide. It's vital that these technologies are available within a generation, when they will be needed to augment or replace parts of the new transportation system we've outlined.

President Bush's ultimate goal of increased energy security is laudable, but the proposals that he calls ambitious don't go far enough. The suggestions we have presented have a better chance to provide us not only with increased energy security, but also, eventually, with energy independence, and they may help reduce the long-term threat to the nation from climate change. We believe this new system will work—and will do so in a way that should not be disruptive. Indeed, doing nothing—allowing the nation's fuel supply and vehicle fleet to remain unchanged right up to the moment when petroleum production begins to decline—would be a catastrophe, one that could be avoided if we were to take action now.

This article is based largely on a paper by West and Kreith in the Journal of Energy Resource Technology (Vol. 128, Sept. 2006, pages 236-243).

Frank Kreith is professor emeritus of mechanical engineering and Ron West is professor emeritus of chemical engineering, both at the University of Colorado in Boulder. The authors have been investigating questions regarding future energy supply for the past six years.

Fahrenheit 3,600

One of the basic rules of gas turbines is that the hotter the gas that enters the work-producing

turbine from the combustor, the greater the thermal efficiency and output. Still, there are limits.Turbine inlet temperatures in the gas path of modern high-performance jet engines usually don't exceed 3,000°F, while non-aviation gas turbines operate at 2,700°F or lower.

But 3,600°F? That temperature exceeds the melting point of iron and the boiling point of molten silver. And yet the turbine airfoils in the new F135 jet engine that powers the Joint Strike Fighter Lightning II are capable of operating at these extreme temperatures. The F135 gas turbine is the first production jet engine in this new 3,600°F class, designed to withstand these highest, record-breaking turbine inlet temperatures.

There have been, in fact, quite a few accomplishments in the gas turbine industry over the last year. GE put into operation a simple-cycle 100 MW turbine that runs at 46 percent efficiency. Pratt & Whitney ramped up production of engines for a new class of aircraft, the very light jet. And construction of the first pebble bed nuclear reactor, set to be built in South Africa, was placed on the schedule.

But 3,600°F? That's hot. The JSF engine represents a bold—and necessary—step forward. This 40,000-pound thrust engine will power all three variants of the JSF: an Air Force fighter that takes off conventionally, a carrier-based Navy jet, and a short takeoff/vertical landing aircraft for the Marines. The STOVL version is the first aircraft to be able to do the "Hat Trick"—take off in a short distance, go into supersonic flight, then hover and land vertically. These varied missions require a very high thrust-to-weight ratio, and thus high turbine inlet temperatures.

The powerful engine for the new Joint Strike Fighter on its test platform in Florida (above) will develop 40,000 lbs. of thrust. The jet engine will come in Navy, Marine, and Air Force versions (below).

Last December, at Pratt & Whitney's Middletown, Conn., plant, Ed Crow, retired senior vice president and head of engineering at Pratt, took a few of us from the University of Connecticut Mechanical Engineering Department to view a F135 engine disassembled after 600 to 800 hours of operation. The blades and vanes of the high turbine, clad with ceramic thermal barrier coatings, are made of single crystal superalloys, which soften and melt at temperatures between 2,200 and 2,600°F. (Single crystal alloys were the subject of an article, "Crown Jewels," in ME magazine in February 2006.) Turbine airfoils closest to the combustor operate in a gas stream that can exceed their superalloy melting point by 1,000°F.

So how do turbine airfoils survive running conditions in this 3,600°F class engine? The vanes and blades are cooled to maintain acceptable service temperatures, some eight-tenths to nine-tenths of their melting temperature. Each high-temperature turbine airfoil is formed from an elaborate investment casting to accommodate the intricate internal passages and surface hole patterns necessary to channel and direct cooling air (bled from the compressor) within and over external surfaces of the airfoil structure. An error in airfoil cooling hole location or in cooling air pressure ratios could cause airfoil gas path inhalation rather than film cooling exhalation, which at the JSF's high turbine gas path temperatures would induce airfoil expiration. The JSF turbine film cooling design is based on some 30 years of gas turbine industry film cooling research and development, and unequivocally pushes forward the state-of-the-art of turbine performance and durability.

The JSF engine is just one product in the $3.7 billion military gas turbine market, which includes jet engine production for the world's fighter aircraft—such as the F15, F16, F22, F35, and Typhoon—military cargo, transport, refueling, and special-purpose aircraft. And that's just a fraction of the total worldwide gas turbine market.

A Steep Climb

David Franus of Forecast International in Newton, Conn., has again this year provided me with values of gas turbine manufacturing production, based on FI's proprietary databases and computer models. FI's values of production of gas turbines are unique in that they are for both aviation and non-aviation, the two disparate parts of the industry, usually reported on separately in trade journals. Worldwide gas turbine production for 2006 amounted to $27.6 billion, up significantly from $22 billion in 2005, but still below the 10-year average of $28.5 billion.

The aviation portion, all for manned aircraft jet and turboprop engines, amounted to $18.5 billion, two-thirds of the 2005 total value of gas turbine production.

The value of gas turbine production for commercial aviation is three to four times that of military, $14.8 billion in 2006. There is a prediction of $16.9 billion in 2010 (a 14 percent increase). This upward trend reflects the growth of the airline industry, evidenced by increased passenger loads (especially for Asian travel) since 9/11 and SARS, and an increase in the number of new airlines. Sales of existing models of Boeing and Airbus aircraft, using a variety of General Electric, Pratt & Whitney, Rolls-Royce, and Snecma engines, are strong, and both airframe companies are developing new models. Boeing has the new subjumbo 787, designed to serve what the company sees as the future demand of air travel, as well as a "new" superjumbo 747-8 family. (The 747 is an incredibly long-lived product line. I remember working on the first JT9D 747 jet engines, back in the 1960s at Pratt & Whitney Aircraft.). Airbus is developing its trouble-plagued superjumbo A380.

The air cargo market is strong and orders for new jet engine-powered freighters are high. Jet engine demand is also strong in regional airline and business aircraft markets.

The Siemens SGT-8000H gas turbine, shown here in a cutaway diagram, is the world's largest, rated at 340 MW with an efficiency of 60 percent.

A booming area for new jet engines is the very light jet, or "air taxi" market (the subject of the article "Very Light and Fast" in January). A VLJ twin-engine aircraft with a pilot and from five to eight passengers, could provide point-to-point, on-demand air taxi service to some of the 5,000 local airports in North America. For flights shorter than 500 miles, VLJ aircraft use could enable air travelers to circumvent the bottleneck created by airport security and could eliminate layovers caused by the existing hub-and-spoke airline system.

Eclipse Aviation, Honda Aircraft Co., Cessna Aircraft Co., Citation, Embraer, and Adam Aircraft have entered the VLJ market, and Eclipse reports orders for 2,500 of its jets. Pratt & Whitney Canada is in full production for several thousand of the VLJ engines, in the 1,000- to 3,000-pound thrust range. Other VLJ engine OEMs are Williams International and Honda/GE.

In contrast with the steadily climbing aircraft market, the value of production for non-aviation gas turbines shows a boom-and-bust quality, rising to a peak of nearly $26 billion in 2001 before dropping back to around $8 billion a few years later. That behavior is caused by the rapid growth in—and sometimes speculative nature of—the electric power market, during this recent era of piecemeal utility deregulation.

Non-aviation gas turbines consist of electrical power generation, mechanical drive (mostly used to drive natural gas pipeline compressors), and marine (Navy, cruise ships, and ferry propulsion). The largest segment of that market by far is electrical power generation, in simple cycle (gas turbine only), combined cycle (gas turbine with its exhaust producing steam for steam turbine generation), and cogeneration (gas turbine, with its exhaust producing steam for heat, as described, for instance, in "Campus Heat and Power," Dec. 2006).

Forecast International predicts significant growth in coming years in demand for gas turbine electrical power generation, rising from $8.6 billion in 2006 to a projected $13.5 billion in 2008, a 60 percent increase. Based on a small sample of OEMs that I interviewed at the big Power-Gen conference and exhibit in Orlando last December, I agree with FI's predictions. In particular, two U.S. OEMs said that the cogeneration market for gas turbines was much stronger in Europe than in the U.S. In the words of one OEM exhibitor, "The sales are strong in those countries that signed the [Kyoto] treaty." Such an observation would seem to be at odds with assertions made by U.S. officials that signing the Kyoto treaty on greenhouse gas emissions would put the U.S. at an economic disadvantage.

Cleaning Coal

In many countries, such as the United States, South Africa, and China, coal is the major energy source, and it is used to produce electricity in steam Rankine cycle plants. At the Sino-American Technology and Engineering Conference I attended in Beijing last October, Xu Kuangdi, the president of the Chinese Academy of Engineering, remarked that of every three power plants currently being built in the world, two were in China, where the major fuel is coal.

Companies and government have been launching projects to design and develop integrated gasification combined-
cycle power plants. These IGCC plants convert coal into syngas, a low calorific value gas composed of carbon monoxide and hydrogen; the syngas is then used as fuel for a gas turbine, whose exhaust provides heat to generate steam to run a steam turbine. Using the same fuel twice, in essence, a combined-cycle power plant can have thermal efficiencies as high as 60 percent. There are now only two IGCC plants in operation in the United States, compared with 1,100 pulverized coal steam power plants, all with thermal efficiencies much, much lower than 60 percent. If IGCCs prove to have reasonable capital costs per kilowatt, the market for gas turbines could be very promising.

The first standardized commercial IGCC plants are being built by GE Energy and Bechtel, for American Electric Power, the U.S.'s largest electrical generator. Also, the U.S. Department of Energy has initiated FutureGen, a program to build the first integrated sequestration and hydrogen production plant. This is to be a zero-emissions fossil fuel plant using, of course, gas turbines.

The very largest electric power gas turbines are identified as H class, a designation that has lightheartedly been interpreted as an abbreviation for "humongous" (see "A Year of Turbulence," ME magazine's Power & Energy, June 2004). A General Electric GE Energy 9H gas turbine weighs in at 405 tons (367,900 kg), and the first one went into natural gas fuel operation at Baglan Bay, Wales, in 2003. In combined-cycle operation this unit can input 520 MW into the U.K.'s electric power grid, at a plant thermal efficiency of just under 60 percent.

Siemens' first H class gas turbine combined-cycle plant is now under construction in Irsching, Germany. It's also slated to have a thermal efficiency over 60 percent, and a plant output of 530 MW. The Siemens SGT-8000H gas turbine itself is rated at 340 MW, making it the world's largest.

The two companies differ in their design philosophy on turbine cooling systems. GE Energy H units are steam cooled—closely tying together the steam (Rankine) and gas turbine (Brayton) cycles—while the Siemens H gas turbine will be cooled by air bled from the compressor.

Wild animals graze along the road to the Koeberg nuclear power station (below). The site, home to a 1,800 MW conventional nuclear power station, will see construction of the world's first pebble bed nuclear reactor in 2008. The new reactor will have an output of 165 MW.

While H machines are designed mainly for base load electric power markets, General Electric's new LMS100 gas turbine is aimed at the mid-merit and daily cycling segments—the difficult-to-predict, must-be-ready-to-start electric peak power providers. The LMS100 is rated at 100 MW and, at 46 percent, has the highest efficiency of any simple cycle gas turbine. It is the first modern production electric power gas turbine that has an intercooler. This is a water-cooled, shell-and-tube heat exchanger through which gas path flow between the high and low compressor is cooled, making for less compressor work. The resulting heated intercooler water can then be used for some other purposes, but more importantly, the net gas turbine output is increased and colder turbine cooling air is made available, boosting thermal efficiency.

The LMS100 is an aeroderivative, based on GE's CF6-80C1 jet engine, but perhaps should be called a hybrid aeroderivative since the machine's low compressor is derived from GE's heavy-frame MS6001FA gas turbine. The first production unit of this innovative, intercooled gas turbine went into operation at Groton, S.D., last year.

This past February, while in Cape Town, South Africa, I visited what will be the site of the world's first nuclear-powered gas turbine electric power plant. The consortium Pebble Bed Modular Reactor (Pty) Ltd. will begin construction by May 2008, and Westinghouse of the U.S., Mitsubishi Heavy Industries of Japan, Nukem of Germany, and South Africa's utility, Eskom, are all participating.

This first PBMR unit will have an output of 165 MW provided by a closed-cycle gas turbine designed and developed by Mitsubishi and operating with helium gas. The helium is heated in a nuclear graphite-modulated, high-temperature reactor, approximately 88 feet high and 20 feet in diameter. The reactor is filled with 450,000 fuel "pebbles," managed in such a way that the reactor need not be shut down for refueling. Each 6 cm diameter graphite pebble (about the size of a tennis ball) is heated by nuclear reactions going on in some 15,000 kernels of uranium dioxide, each about 0.5 mm diameter, dispersed in the pebble, and individually encased in protective layers of carbon and silicon carbide.

The helium enters the pebble bed at 500°C and 9 Mpa, and is heated to about 900°C before it enters the turbine, then on to a recuperator, compressor, intercooler, recuperator, and then back into the pebble bed reactor, thus producing a nuclear-heated, Brayton thermodynamic closed cycle. In a closed-cycle operation, electric load variation is accomplished by varying the amount of helium in the system (A book on the subject, Closed-Cycle Gas Turbines, by Hans Frutschi is available from ASME Press). The PBMR is designed to have a relatively high thermal efficiency: 41 percent, compared to 33 percent for a conventional light water reactor using a Rankine cycle.

One selling point of the design is that any loss of coolant will shut down the nuclear reactions. This first PBMR unit, in fact, will be built right next to Eskom's Koeberg 1,800 MW Rankine cycle nuclear power plant. That facility is located on 7,500 acres of the Koeberg Nature Reserve, on the Atlantic coast less than 20 miles north of Cape Town. It's a very picturesque location for a generating station of any sort, and probably the only nuclear power plant in the world patrolled by wild springboks and zebras.

Lee S. Langston is professor emeritus of mechanical engineering at the University of Connecticut in Storrs. A frequent contributor to Mechanical Engineering, he is the former editor of ASME's Journal of Engineering for Gas Turbines and Power.

پیل سوختی

موتور رفت و برگشتي

توربین گازی و برخی پارامترهای های بروز آن

نانو سیالات

نانو سیالات

گروهي جديد از سيالات که قادر به انتقال حرارت مي‌باشند، نانوسيال ناميده مي‌شوند. نانوسيالات به ‌وسيلة پخش و منتشر کردن ذرات در اندازه‌هاي نانومتري در سيالات متداول منتقل کنندة گرما، به ‌منظور افزايش هدايت گرمايي و بهبود عملکرد انتقال حرارت، ساخته مي‌شوند.
نتايج آزمايش‌هايي که در رابطه با نحوة انتقال حرارت بر روي چندين نمونة نانوسيال انجام شد، نشان مي‌دهد که عملکرد نانوسيالات در انتقال حرارت عموماً بيشتر از آن چيزي است که به ‌صورت نظري پيش‌بيني شده است. اين واقعيت يک کشف اساسي در مسئلة انتقال حرارت مي‌باشد.

از نانوسيالات مي‌توان به ‌منظور توسعة سيستم‌هاي کنترل حرارت در بسياري کاربردها از جمله وسايل نقلية سنگين استفاده نمود. کنترل حرارت يکي از عوامل کليدي در فناوري‌‌هاي مربوط به محصولاتي مانند پيل‌ سوختي و وسايل نقلية دوگانه سوز– الکتريکي مي‌باشد که بيشتر آنها تحت دماهاي عمدتاً کمتر از دماي موتورهاي احتراقي داخلي متداول، عمل مي‌کنند.
بنابراين نياز مبرمي به توسعة سيالات انتقال ‌دهندة حرارت با هدايت گرمايي خيلي بالا و نيز انتقال اين فناوري به صنايع خودرو وجود دارد.
اخيراً پژوهش‌هايي در مورد نانوسيالات فلزي حاوي نانوذراتِ مسِ با قطرِ کمتر از 10 نانومتر که در اتيلن گليکول پخش شده بودند انجام شده است. اين پژوهش‌ها نشان مي‌دهد که در جزء حجمي بسيار اندکي از نانوذرات، رسانايي گرمايي مي‌تواند بيشتر از قابليت رسانايي صرف خود سيال و يا نانوسيالات اکسيدي (مانند اکسيد مس و اکسيد آلومنيوم با قطر متوسط ذرات 35 نانومتر) باشد. همان‌طور که در نمودار 1 نشان داده شده است. به علت اينکه تاکنون هيچکدام از نظريه‌هاي معمول، اثرات ناشي از قطر ذرات و يا هدايت آنها بر روي ميزان هدايت نانوسيالات را پيش‌بيني نکرده‌اند، اين نتايج غير منتظره است.
اخيراً نانوسيالاتي حاوي نانو لوله كربني ساخته شده‌اند و نتايج آزمايش‌هاي انجام شده بر روي اين نانوسيالات نشان داده است که وجود نانولوله‌ها در يک سيال، هدايت گرمايي آن را بطور چشمگيري افزايش مي‌دهد.
جالبتر آنکه افزايش هدايت گرمايي مربوط به نانولوله يک گام از پيش‌بيني ‌هاي انجام شده به وسيلة نظريه‌‌هاي موجود فراتر است. از اين گذشته نمودار هدايت گرمايي اندازه ‌گيري شده بر حسب حجم‌هاي جزئي، به ‌صورت غيرخطي مي‌باشد حال آنکه تئوري‌هاي رايج به وضوح وجود يک نسبت خطي را ميان اين دو پارامتر نشان داده بودند (نمودار 2).
از ويژگي‌هاي کليدي نانوسيالات که تاکنون کشف شده‌‌اند مي‌توان هدايت‌هاي گرمايي بسيار بالاتر از آنچه که سوسپانسيون‌هاي مرسوم از خود نشان داده بودند، وجود نسبت غير خطي ميان هدايت گرمايي و غلظت نانولوله‌هاي کربني در نانوسيالات و نيز وابستگي شديد هدايت گرمايي به دما و افزايش چشمگير در شار حرارتي بحراني را نام برد. هر کدام از اين ويژگي‌ها در جاي خود براي سيستم‌هاي حرارتي بسيار مطلوب مي‌باشند و در کنار هم، نانوسيالات را بهترين کانديدا براي توليد سرد کننده‌هاي مبتني بر مايع مي‌نمايند. اين يافته‌ها همچنين وجود محدوديت‌هاي اساسي در مدل‌هاي انتقال گرمايي متداول براي سوسپانسيون‌هاي جامد/ مايع را به وضوح نشان مي‌دهد.
از جمله عوامل انتقال حرارت در نانوسيالات، عبارتند از: حرکت نانوذرات، سطح مولکولي لايه‌اي مايع در سطح مشترک مايع با ذرات، انتقال حرارت پرتابه‌اي در نانوذرات و تأثير خوشه‌اي شدن نانوذرات از جمله عوامل انتقال حرارت در نانوسيالات مي‌باشند.
يک پروژة جديد با هدف کشف پارامترهاي کليدي، که در تئوري‌هاي موجود و مفاهيم بنيادي مکانيزم‌هاي افزايش انتقال حرارت نانوسيالات از قلم افتاده‌اند، و نيز کشف مبناي تئوري براي افزايش غير عادي هدايت گرمايي نانوسيالات در جولاي سال 2000 با حمايت وزارت انرژي آمريكا و مرکز انرژي علوم پايه به تصويب رسيد.
ساختار نانوذرات در نانوسيالات در حال بررسي و آزمايش بوسيلة منبع فوتوني پيشرفتة آزمايشگاه ملي آرگون مي‌باشد. بر طبق نتايج گزارش شده از دانشگاه A&M تگزاس، اين دانشگاه در حال مطالعه بر روي ارتباط بين جنبش نانوذرات و افزايش انتقال حرارت در آنها مي‌باشد. با استفاده از نتايج جمع‌آوري شده، توسعة يک مدل جديد انتقال انرژي در نانوسيالات که وابسته به اندازة نانوذره، ساختار و تأثير پويايي بر روي خصوصيات حرارتي نانوسيالات مي‌باشد، امکان پذير شده است.
اين نحوة ارتباط رشته‌هاي مختلف علمي و پروژه‌هاي مشترک منجر به کشف مرزهاي جديدي در تحقيقات ترموفيزيک براي طراحي و مهندسي در زمينة توليد خنک‌کننده‌ها خواهد گرديد. تحقيق در مورد نانوسيالات مي‌تواند به يک پيشرفت غير منتظره در زمينة سيستم‌هاي ترکيبي مايع/جامد، براي کاربردهاي بي‌شمار مهندسي از جمله خنک‌کننده‌هاي اتومبيل‌ها و کاميون‌هاي سنگين بيانجامد.
از عمده‌ترين تأثيرات اين تحقيقات مي‌توان به بيشتر شدن کارايي انرژي، کوچک‌تر و سبک‌تر شدن سيستم‌هاي حرارتي، کمتر شدن هزينه‌هاي عملياتي و پاک‌سازي محيط زيست اشاره نمود.

نمودار 2- مقادير اندازه‌گيري شده(منحني ‌هاي پيوسته) و مقادير پيش‌بيني شده(خطوط ناپيوسته) افزايش هدايت گرمايي براي نانولوله در نانوسيالات روغن. به علت تشابه کلية مقادير محاسبه شده در حجم‌هاي کوچک، بعضي از مقادير محاسبه شده با مقياس بزرگ‌تري دوباره بر روي نمودار نمايش داده شده‌اند. خط A: همبستگي کروسر هاميلتون، خطB: همبستگي برادي - بونکاز
(Bonnecaze & Brady)، خط C: نظريه ماکسول

نانوسيالات و کاميون هاي پيشرفته :
به علت نياز به موتورهايي با نيروي بيشتر، توليد کنندگان کاميون دائماً در جستجوي راه‌هايي براي گسترش طرح‌هاي آيروديناميک در وسايل نقليه‌شان هستند. از جمله تلاش‌ها در اين زمينه معطوف به کاهش مقدار انرژي مورد نياز جهت مقابله با مقاومت‌هاي بالا مي‌باشد. در يک کاميون سنگين معمولي، با سرعت 110 کيلومتر در ساعت، در حدود 65 درصد کل بازده موتور، صرف غلبه بر کشش‌هاي آيروديناميک مي‌شود که يکي از دلايل بزرگ اين امر مقاومت هوا مي‌باشد.
در سيستم‌هاي خنک کننده، با توجه به نوع سيال مورد استفاده رادياتورهاي متفاوتي مورد نياز است. جهت انتقال حرارت از موتور به رادياتور و در نهايت آزاد شدن اين حرارت به محيط اطراف، به کارگيري سيالات با ظرفيت‌هاي گرمايي بالا ضروري مي‌باشد.
اين سيالات قادرند بدون افزايش دماي خودشان حرارت را جذب و سپس آن را بسيار آهسته و بدون نياز به مقدار سيال بيشتر به محيط اطراف منتقل نمايند که اين انتقال آهستۀ گرما به محيط، موجب بزرگي اندازۀ رادياتورهاي وسايل نقليه معمولي مي‌شود.
اگر سرعت انتقال حرارت توسط سيالات به‌گونه‌اي افزايش يابد، طراحي رادياتورها آسان و مؤثرتر شده و مي‌توان آنها را کوچکتر ساخت. همچنين اندازۀ پمپ‌‌هاي خنک کنندۀ وسايل نقليه مي‌تواند کاهش يابد. موتورهاي کاميون‌ها نيز مي‌توانند به علت کارکردن تحت دماهاي بالاتر نيروي بيشتري توليد نمايند. افزايش هدايت گرمايي خنک‌کننده‌ها نيز مي‌تواند ايده‌اي مناسب براي توليد پيل‌هاي سوختي پيشرفته و وسايل نقليۀ دوگانه سوز/الکتريکي باشد.
محققان آزمايشگاه آرگون در حال پيدا کردن روشي براي افزايش زياد هدايت گرمايي خنک کننده‌ها در موتورهاي معمولي بدون بروز تأثيراتي مغاير با ظرفيت‌هاي گرمايي آنها هستند.
بخش انرژي آزمايشگاه آرگون به طور مشترک با کمپاني Valvo Line، در حال کار در زمينۀ توسعۀ خنک‌کننده‌هاي نانوسيالي و روغن‌هاي روان‌ساز براي موتورهاي کاميون مي‌باشد.
محققان آرگون هم‌اکنون از يک روش يک مرحله‌اي براي توليد نانوسيالات بر مبناي نانوذرات فلزي و يک روش دومرحله‌اي براي توليد نانوسيالات بر مبناي نانوذرات اکسيدي، استفاده مي‌کنند که هر دو شيوه، روش‌هاي نسبتاَ آسان و اقتصادي براي توليد نانوسيالات هستند.
هم‌اکنون محققان آرگون در حال بررسي تأثير دوده در روغن موتور مي‌باشند. ميزان دوده در روغن موتور گاهي اوقات بيشتر از حد انتظار است. با وجود اينکه ذرات دوده به کوچکي ذرات نانومتري موجود در نانوسيالات نيستند، محققان دريافتند تجمع آنها در روغن موتور منجر به افزايش 15 درصدي در هدايت گرمايي روغن موتور مي‌شود.
بر اساس اين يافته‌ها محققان حسگري توليد نمودند که با اندازه‌گيري ميزان افزايش هدايت گرمايي ذرات دودۀ جمع شده در روغن موتور قادر به نشان‌دادن نحوۀ عملکرد موتور مي‌باشد.

نانوسيالات فلزي و موتورهاي خنک‌کننده :
ويژگي‌هاي موتورهاي ديزلي از نظر محدوديت در واکنش‌ها و راندمان کار به سرعت در حال دگرگون شدن است. سيستم‌هاي خنک‌کننده بايد بتوانند تحت دماهاي بالاتر کار کرده و مقادير بيشتري گرما به محيط اطراف منتقل کنند. اندازۀ رادياتورها نيز بايد کاهش يابد تا تجهيزات اضافي کاميون‌ها حذف شده و رفت‌و‌آمد با آنها ساده‌تر گردد. به‌طور واقع‌بينانه، محصور کردن نيروي خنک‌کنندۀ بيشتر در فضاي کمتر، تنها با به کار بردن فناوري‌‌هاي جديدي مانند نانوسيالات ممکن خواهد بود.
کاربرد ديگر اين مدل‌سازي‌ها، پيش‌بيني ميزان هدايت گرمايي يک نانوسيال بر مبناي غلظت، دماي عملياتي و اندازۀ نانوذرات پخش شده در سيال مي‌باشد. از اين گذشته اين امکان وجود دارد که خواص نانولايه‌هايي که روي سطح نانوذرات معلق تشکيل مي‌شوند، عاملي براي افزايش بيشتر هدايت گرمايي نانوسيالات مي باشد.
دو مکانيزم کليدي حرکت براوني و نانولايه‌ها، توأماً از مهم‌ترين عوامل افزايش هدايت گرمايي سيالات انتقال دهندۀ گرما مي‌باشند.
محققان آزمايشگاه آرگون در حال بررسي خطرات احتمالي نانوسيالات براي سيستم هاي رادياتور مي‌باشند. آنها موفق به ساخت وسيله‌اي شدند که قادر به اندازه‌گيري و آزمايش تأثيرجريان‌هاي خنک کنندۀ متفاوت بر عملکرد يک رادياتور مي‌باشد.
تحقيقات آينده بيشتر بر روي جنس نانوذرات به کار‌‌رونده در ساخت نانوسيالات از جمله ذرات آلومينيوم و نانوذرات اکسيد فلزي روکش شده متمرکز خواهد شد.