Powertrain and Cabin Cooling Performance Improvement by Optimization of Its Components

<div class="htmlview paragraph">Evaluations were made of the short-term (5 minute) durability at high temperatures of 85 mm outer diameter ceramic radial turbine rotors made of silicon nitride using an improved hot gas spin test rig.</div> <div class="htmlview paragraph">Under no load conditions, the rotors withstood a maximum turbine tip speed (Ut) of 550 m/s without bursting at a turbine inlet gas temperature (TIT) of 1240°C.</div> <div class="htmlview paragraph">Under partially loaded conditions, they withstood up to Ut of 500 m/s at TIT of 1280°C without bursting.</div> <div class="htmlview paragraph">The test results indicated that the knee point temperature in terms of TIT at which the failure tip speed decreased sharply was about 40°C higher under partially loaded condition than under no load condition.</div> <div class="htmlview paragraph">The temperature and stress distribution in the turbine in the hot gas spin test were calculated by the finite element analysis, which supported the dependence of the knee point temperature in terms of TIT at spin test on load condition.</div>

<div class="htmlview paragraph">Certification of heavy-duty diesel requires engines to be tested on an engine dynamometer and meet certification in accordance with specific procedures and cycles. However, real-world emissions have been observed to be significantly different from in-laboratory testing. The brake-specific emissions from vehicles are influenced by various operating parameters such as engine speed, load, traffic flow and ambient conditions, hence, vary from the values obtained from the certification tests. In the future, US EPA and other state regulating bodies will require the engine manufacturers to measure in-use emissions from vehicles operating under “real-world” operating conditions.</div> <div class="htmlview paragraph">A test vehicle instrumented with West Virginia University's (WVU) Mobile Emissions Measurement System (MEMS), a portable onboard tailpipe emissions measurement system, was used to obtain engine operating conditions, vehicle speed and in-use emission rates of CO<sub>2</sub> and NO<sub>x</sub>. The vehicle was driven on a specific route, which included a mix of highway and city driving patterns.</div> <div class="htmlview paragraph">Analysis was performed to determine the amount of time the engine spent in the NTE (Not-to-Exceed) zone of operation, and also over continuous 30s windows of NTE zone operation for the different driving routes. An attempt was made to establish a relationship between the time spent in the NTE region, and excursions in brake-specific emissions.</div> <div class="htmlview paragraph">Modal analysis was performed to determine the episodic nature of events and emissions during engine operation within the Not-to-Exceed (NTE) zone of operation, for each of the selected routes. The contribution of each mode of operation to variations in emissions rates has been documented.</div> <div class="htmlview paragraph">Analysis was performed to determine the effect of employing 30s, and the continuous windows on work done, and the consequent effect on brake-specific emissions in the NTE zone of operation. Results indicate a difference in the number of NTE windows of operation, and also in values of brake-specific emissions calculated by the two methods.</div>

<div class="htmlview paragraph"> </div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">This paper summarizes the numerical development of a cooling package in a vehicle. The radiator and condenser fan performance curves are predicted using Computational Fluid Dynamics (CFD) approach using a numerical AMCA (Air Motion Control Association) chamber. The same procedure is extended to generate the combined fan performance curves. System resistance curves at various vehicle speeds are determined. To determine the vehicle system resistance at various vehicle speeds, a full vehicle CFD model in a numerical wind tunnel is developed and analyzed at different fan speeds.</div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">The changes in radiator flow for different scenarios such as change in fan geometry and the removal of condenser fan are outlined in this work.</div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">The study is then extended to predict radiator hot flow and coolant inlet temperatures at different vehicle load conditions. An analytical method to determine hot air flow and air temperature at radiator exit is developed. This approach is extended to predict coolant inlet temperatures, using the radiator performance data. This can further be used to compute the required change in radiator airflow to meet the coolant inlet temperature targets. The feasibility of removing the condenser fan and still meet the temperature targets is also outlined.</div> <div class="htmlview paragraph"> </div>

<div class="htmlview paragraph">Presenting a brand new approach to heat exchangers for engines, transmissions, hydraulic systems, etc.</div> <div class="htmlview paragraph">This new heat exchanger is made of only two pieces of circular extruded aluminum profiles: Core and shell. No soldering: The core and the shell is assembled by a minimum of automated work.</div> <div class="htmlview paragraph">In an oil to water cooling application, the active surface on the oil side of the core is enlarged by fins 0.2 mm thick, 0.3 mm spacing, and 3 mm high. The fins are made in unique production machines and enlarge the active surface area approximately five times compared to a conventional heat exchanger of the same dimensions.</div> <div class="htmlview paragraph">The principle utilizes the low pressure drop at laminar flow and avoids the disadvantage of low heat transfer after a certain laminar flow length. The result is approximately three times higher oil heat dissipation, combined with very low oil pressure drop, compared to conventional technique.</div> <div class="htmlview paragraph">The inner surface of the core, the water side, is extremely tolerant to dirty water and gives negligible pressure drop.</div> <div class="htmlview paragraph">This new heat exchanger is made of only one metal, aluminum. The characteristics of corrosion are therefore easy to define.</div>

<div class="section abstract"><div class="htmlview paragraph">The paper presents a numerical activity directed at the analysis and optimization of internal combustion engine water cooling jackets, with particular emphasis on the fatigue-strength assessment and improvement.</div><div class="htmlview paragraph">In the paper, full 3D-CFD and FEM analyses of conjugate heat transfer and load cycle under actual engine operation of a single bank of a current production V6 turbocharged diesel engine are reported.</div><div class="htmlview paragraph">A highly detailed model of the engine, made up of both the coolant galleries and the surrounding metal components, i.e., the engine head, the engine block, the gasket, the valve guides and valve seats, is used on both sides of the simulation process to accurately capture the influence of the cooling system layout under thermal and load conditions as close as possible to actual engine operations.</div><div class="htmlview paragraph">Concerning the CFD side, a 50-50 binary mixture of ethylene-glycol and water is used in order to correctly reproduce the coolant behavior, while boundary conditions are derived from a combination of experimental measurements and a CFD-1D model of the whole engine.</div><div class="htmlview paragraph">In order to find a proper CFD setup for the optimization of the thermal behavior of the engine, a preliminary comparison between experimental temperature distribution within the engine head and CFD forecasts is carried out. Eight thermocouples are used to measure the engine head local temperature at some critical locations.</div><div class="htmlview paragraph">Among the many competing numerical sub-models involved in the CFD simulations, particular attention is devoted to the modeling of phase transition and vapor nuclei formation within the coolant galleries.</div><div class="htmlview paragraph">Concerning the FEM side, thermo-mechanical analyses are carried out aiming at addressing the design optimization of the engine in terms of fatigue strength. In view of the wide range of thermal and load conditions, both high-cycle and low-cycle fatigue must be properly characterized by means of ad-hoc criteria. An energy-based criterion specifically suited for low-cycle fatigue regions is therefore superimposed to well-established S-N o ε-N criteria for the high cycle fatigue regions.</div><div class="htmlview paragraph">The proposed methodology shows very promising results in terms of point-wise detection of possible engine failures and proves to be an effective tool for the accurate thermo-mechanical characterization of internal combustion engines under actual life-cycle operations.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Between June 2000 and September 2008 the University of North Florida, Institute of Police Technology and Management (UNF, IPTM) performed over 200 deceleration tests on over 70 commercial vehicles in a variety of configurations including various vehicle types, load conditions, and tests with and without the ABS system activated. The vehicle types tested were tractor w/van type trailer, tractor only (bobtail), straight box/service trucks, dump trucks, fire trucks, concrete mixing trucks, double trailers, articulated tankers, school and metro buses and articulated flatbeds.</div><div class="htmlview paragraph">Vehicles were instrumented to record selected system performance parameters such as brake canister pressure rise, vehicle speed, position at brake pedal application, vehicle acceleration, etc.</div><div class="htmlview paragraph">This paper reviews and summarizes the stopping distance data from these tests and provides insight into commercial vehicle stopping distance, drag factor for all of the tested vehicles and configurations. It will also look at how vehicle type, load condition, and ABS affect stopping distances. This information will be of value to accident investigators, regulators, and vehicle designers, as it will provide significant data regarding the braking performance of these vehicles.</div></div>

<div class="section abstract"><div class="htmlview paragraph">In order to achieve the best automotive vehicles, companies seek for innovation and new technologies to improve their vehicles. Lately the embedded electronic has been used to add intelligence to a purely mechanical systems.</div><div class="htmlview paragraph">The reduction of fuel consumption, one of the biggest concerns of automotive engineering, for the last couple of years, depends on many factors. Some those factors are engine type, fuel quality, vehicle load, gearshift pattern, vehicle usage, driver behavior and the cooling system technology.</div><div class="htmlview paragraph">The fan applied in cooling system uses part of engine power to run, influencing the fuel consumption and contributing to the global noise level of vehicle, being directly associated with passenger’s comfortable.</div><div class="htmlview paragraph">One alternative in study is the use of a set of electric fans that can be triggered independently, in order to increase the heat exchange in specific places of radiator, while reducing the noise and run time.</div><div class="htmlview paragraph">This paper will present a comparison between the controlled electrical fans assemble and the mechanical fan (viscous clutch).</div></div>

<div class="htmlview paragraph">In the past decade, SCR deNOx technology with urea injection has grown to maturity. European OEMs will apply SCR deNOx to meet future heavy-duty emissions legislation starting with EURO-4 (2005/2006). Numerous research programs in Europe and the US have shown a variety of system layouts and control strategies. The main differences are formed by:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">the engine-out NO<sub>x</sub> calibration</div> </li> <li class="list-item"><div class="htmlview paragraph">the application of an NO to NO<sub>2</sub> catalyst</div> </li> <li class="list-item"><div class="htmlview paragraph">open-loop or closed-loop urea dosage control.</div> </li> </ul> </div> <div class="htmlview paragraph">This paper gives an overview of possible SCR system configurations that are required for different stages of future emission legislation.</div> <div class="htmlview paragraph">Engine-out NO<sub>x</sub> emission is strongly influenced by ambient conditions. Projections in this study show that a combination of cold climate and a wintergrade fuel is the most severe: it may lead to 30% lower engine-out NO<sub>x</sub> emission with respect to laboratory conditions. The varying engine-out NO<sub>x</sub> emission requires a safety margin in the case of an open-loop controlled system in order to avoid excessive NH<sub>3</sub> slip.</div> <div class="htmlview paragraph">Calculations in this paper show that Euro 4 limits can be met with open-loop controlled urea dosage; an NO to NO<sub>2</sub> catalyst is even not required. For other future emission legislation (Euro 5, US 2007 and US 2010), it becomes difficult to safely achieve the limits with open-loop control. US 2007 and 2010 legislation require an NO to NO<sub>2</sub> catalyst because of the low average load and consequently low exhaust gas temperatures. Engines that are developed to meet US 2010 legislation need special measures to increase the exhaust gas temperature and to reduce engine-out NO<sub>x</sub> below 2 g/kWh.</div> <div class="htmlview paragraph">In all cases, optimal hydrolysis and mixing conditions are of major importance. High speed photography and droplet size measurements are presented as methods for characterizing and modeling aqueous urea spray patterns. The information from these measurements is used as input parameters for simulation tools. These consist of a 2D/3D CFD program for urea mixing analysis and a 1D SCR system model for development of dosage control and optimization of catalyst dimension.</div> <div class="htmlview paragraph">Finally, simulations with the SCR system model are compared with measurements on the engine test bench.</div>

<div class="htmlview paragraph"> </div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">In 1976, the Office of Conservation of ERDA sponsored a survey to identify deficiencies in heat exchanger technology affecting the timely development, demonstration and commercialization of advanced energy recovery and conversion systems of interest to Conservation. Heat exchanger deficiencies identified in this survey have been grouped into four categories: (1) performance and reliability penalties inflicted by the heat exchanger environment (i.e., those fluids in contact with the heat exchanger); (2) design and construction of efficient/reliable high temperature heat exchangers (material temperatures exceeding 1800°F); (3) poor economics in recovering low grade waste heat; (4) lack of information on the long-term performance and reliability of newly developed heat exchangers. The Heat Exchanger Technology (HET) Program was created in 1976 in response to these needs. Today, the HET Program resides within the Office of Fossil Energy Technology of the Department of Energy. Although certain HET projects relate directly to coal technology needs, the primary thrust of this program is, as it was originally, conservation oriented. This paper will (a) discuss the origin and objectives of the HET Program, (b) describe projects comprising the HET Program, (c) present a status report on current activities.</div> <div class="htmlview paragraph"> </div>

<div class="htmlview paragraph">In accident reconstruction, the distance a pedestrian has been projected by an impact may be used to provide an estimate of the speed of the striking vehicle. With tyre marks becoming less common, as ABS braking is introduced, the method is gaining in importance.</div> <div class="htmlview paragraph">Speed estimation from throw distance rests on an empirical basis of field studies, which relate the distance projected to the speed of the vehicle. However field studies by themselves provide no understanding of the physical process. That understanding is important in the consideration of the effects of site characteristics, such as gradient or coefficient of friction.</div> <div class="htmlview paragraph">The paper presents the equation of motion for an idealised particle, travelling over a surface where the upward reaction from the surface varies from moment to moment, including times when the particle is airborne and the reaction is zero. A simple formula is derived linking the minimum initial speed, the coefficient of friction and the total distance travelled:-</div> <div class="htmlview paragraph"> <div id="FD1" class="formula"> <div class="graphic-wrapper"><img class="article-image equation block" src="930659_fig0001.jpg" alt="No Caption Available"/></div> </div> </div> <div class="htmlview paragraph">A series of tests was carried out to check this relationship experimentally. A dummy was projected on an airborne trajectory and the distance travelled was measured. It was found that whilst there were differences from the simple formula, those differences were small. For most practical purposes the simple formula provides a speed estimate of sufficient accuracy.</div> <div class="htmlview paragraph">This speed estimate is for the minimum speed at which the pedestrian must have been projected. The average speed will be slightly higher and the speed of the striking vehicle higher again. Comparison with the results of field studies suggests that these effects add on some 20% or so.</div>

<div class="section abstract"> <div class="htmlview paragraph">This Recommended Practice provides a procedure for measuring and documenting the aerodynamic performance in a full-scale wind tunnel of passenger vehicles, i.e., mass-produced cars and light-duty trucks intended primarily for individual consumers. Testing or numerical modeling of pre-production and/or reduced-scale models is outside the scope of this document. Aerodynamic <i>development</i> procedures, i.e., methods to improve or optimize aerodynamic performance, are also excluded.</div> <div class="htmlview paragraph">It is well-known that aerodynamic performance results depend significantly on vehicle content and loading, as well as the wind tunnel itself (type, scale, and simulation qualities of the wind tunnel). Publication of non-standard test results causes unnecessary additional development work and incorrect perception of a vehicle’s anticipated aerodynamic performance by government, academia, and the general public.</div> <div class="htmlview paragraph">The intent of this document is to promote uniformity and traceability of published aerodynamic performance data acquired in a wind tunnel, thereby enhancing the public reputation and credibility of the aerodynamics discipline in the total vehicle development process.</div> <div class="htmlview paragraph">Measurement of the aerodynamic performance according to this Recommended Practice requires a full-scale wind tunnel test on a production-ready, full-scale vehicle according to specifications for vehicle loading, content, and wind tunnel conditions.</div> <div class="htmlview paragraph">The measurement and resulting documentation for a particular vehicle shall be reported only by the company that intends to produce the vehicle. Whenever there is an opportunity for interpretation of the document, a good faith effort shall be made to obtain the vehicle’s typical in-service performance and avoid finding the best possible performance under the best possible circumstances.</div> <div class="htmlview paragraph">Use of and compliance with this Recommended Practice is voluntary; however, it is mandatory for those advertising or otherwise publishing aerodynamic performance as “measured according to SAE J2881.” Conversely, any advertised or otherwise published result carrying this or a substantially similar designation must have the necessary documentation accepted by and on file with the SAE in accordance with the procedures defined in this Recommended Practice.</div> <div class="htmlview paragraph"><span class="xref">Appendices B</span> and <span class="xref">C</span> contain the necessary submittal documents for compliance with this Recommended Practice. When a submittal is made, the chairman of the Road Vehicle Aerodynamics Forum Committee (RVAC) or his/her designee shall review the submittal for proper completion according to the requirements herein, but without consideration of the technical merit of the claimed performance. After the chairman’s review, SAE will maintain an electronic database of all submittals.</div> <div class="htmlview paragraph">The database shall be available only to members and liasion members of the RVAC. Any RVAC member who retrieves information from the database shall do so with the understanding that the information is to be considered confidential within his or her company.</div></div>

<div class="htmlview paragraph">The Space Station Freedom's US Laboratory. Habitat and Logistics Modules will each be outfitted with separate racks in the floor, celling, and port and starboard walls. The use of racks will facilitate Installation of hardware related to operation of the vehicle and that related to customer accommodations.</div> <div class="htmlview paragraph">The equipment that will reside in the racks will generate heat, either in the consumption of electrical energy or by exothermic chemical reactions. Therefore, it is incumbent upon the vehicle to provide cooling to this equipment by having a mechanism to remove this heat and direct it to a rejection system.</div> <div class="htmlview paragraph">The heat can be removed in two ways, either by direct conduction/convection into a circulating liquid coolant (single phase water) loop, or by convection Into a relatively cool air flowing through or around the heat generator. The latter, described as Avionics Air (AA) Cooling, is the subject of this paper.</div> <div class="htmlview paragraph">Two approaches have been developed for AA cooling. The first approach uses a large central fan and heat exchanger (hence called the “Centralized” approach) which maintains a supply of cooled air to module racks, via a network of interconnected ducting and flow isolation valves.</div> <div class="htmlview paragraph">The alternate approach uses individual fan/heat exchanger packages for each rack, and is known as the “Distributed” approach.</div> <div class="htmlview paragraph">This paper will summarize the features of each of the two air cooling approaches, comparing benefits and limitations of each.</div>

<div class="htmlview paragraph">The Coordinating Research Council (CRC), California Air Resources Board (ARB), and Texas Commission on Environmental Quality sponsored a program to evaluate the effects of air conditioning (AC) operation on vehicle emissions and fuel economy.</div> <div class="htmlview paragraph">Phase 1 of this work measured the effect of AC use with vehicles operated over several standard driving cycles and verified results previously obtained by other investigators. Phase 2 provided a better understanding of the effects of the interactions between ambient conditions (solar load, temperature, and humidity) and AC operation on emissions and fuel economy. The Phase 2 program also verified results of Phase 1 by using a different population of vehicles.</div> <div class="htmlview paragraph">The program results demonstrated that AC operation had a substantial impact on emissions and fuel consumption. Operation of the vehicle AC system over a range of environmental conditions resulted in consistent increases in vehicle emissions of nitrogen oxides (NO<sub>x</sub>) and carbon monoxide (CO). NO<sub>x</sub> increased from 0.1 to 0.6 g/mile, depending on the severity of the test cycle and ambient conditions. CO increased from 0.5 to 12 g/mile. However, analyses indicated that increases in CO were actually due to the increases in ambient temperatures that were employed in the experiments.</div> <div class="htmlview paragraph">The application of solar load to the vehicle increased the impact of AC operation. The application of solar load increased NO<sub>x</sub> emissions from 0.10 to 0.14 g/mile.</div> <div class="htmlview paragraph">Although this experiment was not designed to specifically address fuel economy, operation of the vehicle AC system caused substantial decreases in vehicle fuel economy, ranging from 2.5 to 4.5 miles/gallon. The addition of solar load increased the effect on fuel economy, primarily at less severe ambient conditions. Solar load caused a decrease of 1.3 miles/gallon at 80°F and moderate humidity.</div> <div class="htmlview paragraph">The results of the program were intended to aid in the improvement of vehicle emissions inventory models. NO<sub>x</sub> emission increases due to the use of AC ranged from 15% to 100% of baseline values. This level of effect indicates that AC use should be well accounted for in these models.</div>

<div class="section abstract"><div class="htmlview paragraph">The most widely used type of windshield wiper system employs a coil spring for wiper arm pressure generation. This spring is fixed between the arm head (fixed part) and wiper arm (moving part) and the tension in the spring is responsible for pressure generation. The present arrangement although being unsophisticated design, has following drawbacks: <ul class="list disc"><li class="list-item"><div class="htmlview paragraph">Inability to change wiper arm pressure according to change in vehicle speed.</div></li><li class="list-item"><div class="htmlview paragraph">Inability to provide constant arm pressure during the complete range of motion along varying curvature of windshield.</div></li><li class="list-item"><div class="htmlview paragraph">Inability to reduce/remove the continuous pressure on wiper blade when vehicle is parked for long durations resulting in permanent deformation of wiper blade rubber.</div></li></ul></div><div class="htmlview paragraph">This paper describes how electromagnets can be used to overcome the above stated inherent limitations of the windshield wiper system. An electromagnet is a device which produces magnetic field on application of electric current. It consists of electrical conductor wound around a magnetic core. Unlike a permanent magnet whose magnetic field is fixed, the magnetic field produced by electromagnets can be changed or even reversed very quickly by controlling the input current. Since, magnetic fields attract or repel each other depending upon their direction, hence, electromagnets can be used to produce variable force of attraction or repulsion. This enables electromagnets to be used as a spring with adjustable stiffness.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Developing a knowledge-based predictive driver-aid system requires a strategy that meets the needs and goals, as well as rigorous methods. This paper presents the strategy adopted and the first results obtained in the development of the Navigation Aided Intelligent Cruise Control (N.A.I.C.C.) system. Once the vehicle is located on the route, this new copilot can: <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">define the travel direction and the vehicle speed,</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">determine the distance to the next bend and its characteristics,</div></li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">predict the optimal speed to negotiate the next bend considering the road profile, the constraints given by the driver and the information provided by the sensors mounted on the vehicle.</div></li></ol></div><div class="htmlview paragraph">Then, used in the warning mode (“Driver Alarm Mode”), N.A.I.C.C. informs the driver of the danger of the situation (excessive speed) or, in the intervention mode (“Velocity Control Mode”), N.A.I.C.C. adapts the speed to the predicted reference. In this latter operating mode, N.A.I.C.C. can be considered as an advanced intelligent cruise control system. Real experiments were carried out with the laboratory test car to validate each module described.</div></div>