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Viewing 61 to 90 of 9983
2015-04-14
Technical Paper
2015-01-0816
Carlos Felipe Forigua Rodriguez, Juan Mantilla
A constant volume, zero-dimensional reactor for ideal gas mixtures (CVR) is implemented using Cantera within KIVA-4 to simulate a homogeneous charge compression ignition engine (HCCI). Only partial densities are exchanged between Kiva and Cantera. An initial partial density is calculated by KIVA for Cantera. New densities are generated by Cantera using the CVR and are given back to Kiva. Finally, the calculations are completed by Kiva in the main iteration scheme. No further modifications for constitutive equations nor models were made to KIVA-4 nor Cantera. To maintain the constant volume assumption in each cell and solve the CVR a double adaptive time step is used within the CFD code. One timestep is for the chemical reactor and another for the fluid phase. The use of Cantera allowed a time scheme with a large timestep por the CFD and a comparatively small time step for the kinetic reactions. For the fluid phase, time step is increased if there is a low heat release in all cells.
2015-04-14
Technical Paper
2015-01-1701
Luciano Lukacs
The challenges around global products have been lately one of the key challenges for the Lighting community. This paper will present a survey which was held with costumers from China, India, Europe and Brazil understanding the difference and similarities regarding the lighting attributes. it brings also a discussion how to develop a lamp globally that fulfils everyone's needs and addresses potential trade-offs in design and performance.
2015-04-14
Technical Paper
2015-01-0353
Kaushal Kumar Jha, Ravi Badathala
The prime focus of automotive industries in recent times is to improve the energy efficiency of automotive subsystem and system as whole. This is being done by harvesting the waste energy, averaging the peak thermal loads using thermal energy storage (TES) materials and devices. The phase change materials (PCM) well suits the requirement of energy storage/release according to demand requirement. One such example of TES using PCM is extended automotive cabin comfort during vehicle idling and city traffics including start/stop of the engine at traffic stops. PCM as TES poses high density and capacity in thermal energy storage and release. It is due to latent heat absorption and release during phase change. Generally the latent heat of a material compare to it sensible heat is much higher, almost an order of 2. For example, latent heat of ice is almost 160 times higher than sensible heat for a kelvin temperature rise of ice. During the phase change temperature of PCM remain constant.
2015-04-14
Technical Paper
2015-01-0342
Forrest Jehlik, Eric Wood, Jeffrey Gonder, Sean Lopp
It is widely understood that cold-temperature powertrain operation negatively impacts vehicle fuel use due to heat transfer losses, increased friction (high viscosity engine oil), and enrichment strategies (accelerated catalyst heating). In addition, various drive cycle characteristics significantly impact overall consumption. However, relatively little effort has been dedicated to thoroughly quantifying these impacts across a large number of driving cycles and ambient conditions. This work leverages experimental vehicle data collected at various ambient conditions to develop a simplified modeling framework for quantifying thermal effects on energy consumption over a wide array of real-world usage profiles. Additionally, mitigation strategies including energy retention and exhaust heat recovery are explored with benefits quantified for each approach.
2015-04-14
Technical Paper
2015-01-1612
Wei Liu
The hydraulic retarder is a significant auxiliary braking device for the heavy duty vehicle. Traditionally, cooling circulation of the hydraulic retarder was coupled with the engine cooling system, and the thermal energy of the transmission oil would be cooled by the engine radiator ultimately. For this scheme, radiator’s spare heat removal capacity could be fully utilized whereas the cooling system is very complicated and is hard to maintain. Furthermore, the corresponding of thermal management system lags behind the power change of the retarder. In this research, integrated cooling evaporation system is developed for the hydraulic retarder, which makes the cooling water contact with the transmission oil through the wall of the fixed wheel so that it can rapidly response to the thermal variation of the retarder, keep the stability of the oil temperature and meanwhile reduce the risk of cooling medium leakage.
2015-04-14
Technical Paper
2015-01-1708
Tibor Kiss, Jason Lustbader
For electric vehicles (EVs), there is a great need for highly optimized thermal management systems. Due to the relative shortage of waste heat, heating the passenger cabin in electric vehicles is difficult. Cooling the cabin can take a high portion of the energy available in the battery, significantly reducing vehicle efficiency and range. The range reduction can be as much as 50% by at least one report. Therefore, compared to IC engine driven vehicles, different heating methods and more efficient cooling methods are needed, which can make the electric vehicle’s thermal management system more complex. The more complex systems typically allow various alternative modes of operation which can be selected based on driving and ambient conditions. Investigating a number of system alternatives and determining the best ranges for the various operating modes with experimental methods can be very time consuming.
2015-04-14
Technical Paper
2015-01-0340
Jan Eller, Thomas Binner, Heinrich Reister, Nils Widdecke, Jochen Wiedemann
There is a growing need for life-cycle data – so-called collectives – when developing components like elastomer bearings. Current extreme load cases are not sufficient for establishing such collectives. Consequently, the Idle load case is examined at Mercedes-Benz Car Group as a collective load case for Vehicle Thermal Management (VTM) numerical simulations in early development stages. It combines validation opportunities for HVAC, cooling and transmission requirements in hot-country-type ambient conditions. Experiments at climatic wind tunnels show steady conditions at the end of the case. With a standard Mercedes-Benz 7G transmission temperatures rise in driving gear and fall to a steady state during the subsequent section in parking gear. This effect propagates to elastomer bearings which are the focus of this study. Decoupling of the torque converter entails no dependence on transmission gear setting, anymore.
2015-04-14
Technical Paper
2015-01-0355
Matthew A. Jeffers, Larry Chaney, John Rugh
When operated, the climate control system is the largest auxiliary load on a vehicle. This load has significant impact on fuel economy, and more importantly, it drastically reduces the driving range of electric-drive vehicles (EVs). Heating is even more detrimental to EV range than cooling, since no engine waste heat is available. Reducing the thermal loads on the HVAC system will extend driving range and increase the market penetration of EVs. Researchers at the National Renewable Energy Laboratory are evaluating strategies for vehicle climate control load reduction, with special attention toward GCEDVs. The goal is to increase EV range by 10% during operation of the climate control system. Outdoor vehicle thermal testing and computational modeling are jointly used to explore possibilities for improved thermal management and to evaluate the effectiveness of load-reduction technologies. A thermal comfort model is also being used to evaluate zonal climate control concepts.
2015-04-14
Technical Paper
2015-01-0362
Neal Lawrence, Stefan Elbel
Much attention has been given in recent years to the use of two-phase ejectors and particularly to the performance of the standard ejector cycle with a liquid-vapor separator. However, this cycle may not be the best choice for automotive applications due to the large size required by an efficient separator as well as the cycle’s performance at conditions of lower ejector potential. A limited amount of recent research has focused on alternate two-phase ejector cycles that may be better suited for automotive applications. One of these cycles, using the ejector to allow for evaporation at two different temperatures and eliminating the need for a separator, will be the subject of investigation in this paper. Previous investigations of this cycle have been mainly theoretical or experimental; this paper aims to provide a numerical analysis of the effect of evaporator design on the performance of the ejector cycles.
2015-04-14
Technical Paper
2015-01-1657
Ahsanul Karim, Meisam Mehravaran, Brian Lizotte, Keith Miazgowicz, Yi Zhang
A computational aero-acoustics simulation on the aerodynamic noise generation of an automotive radiator fan assembly is carried out. Three-dimensional Computational Fluid Dynamics (CFD) simulation of the unsteady flow field was performed including the entire impeller and shroud to obtain the source of an audible broad-band flow noise between 2 to 4 kHz. Static pressure probes placed around the outer-periphery and at the center of the impeller inlet side and, at the shroud cavities to capture the noise sources. The static pressure at all probe locations were FFT (Fast Fourier Transform) processed and sound pressure level (SPL) was calculated. The sound pressure levels from the fan outer-periphery probes show the dominant source of blade passing frequency (BPF) and the broad-band noise. The BPF level is the strongest in fan outer-peripheral region because of large pressure fluctuations as a result of blade-passing.
2015-04-14
Technical Paper
2015-01-1693
Mark Allen, Graham Hargrave, Petros Efthymiou, Viv Page, Jean-Yves Tillier, Chris Holt
It is well known that gases enter the coolant flow in internal combustion engines, and must be removed from the flow to retain cooling performance, while retaining a volume of gas in the header tank for thermal expansion and pressure control. The main gases present are air remaining from filling of the system, exhaust emissions from leakage across the head gasket, and also coolant vapour. These gases reduce the performance of the coolant pump, eventually stalling it, and also reduce the heat transfer coefficient of the fluid. This is due to the reduction in the mass fraction of liquid coolant, and the change in fluid turbulence. The aim of the project undertaken for this paper was to provide understanding of the features that are important in the design of an efficient phase separator. This study analysed several commercially available phase separators of the ‘swirl pot’ type to provide benchmarking of their gas extraction efficiency.
2015-04-14
Technical Paper
2015-01-1695
Satoki Tada, Yukihiro Isoda, Takahiro Nagai, Hirofumi Fujiu, Shunji Kumagai, Hideaki Abe, Yoshikazu Shinohara
As an appropriate material for automotive thermoelectric generators, which directly convert waste heat of exhaust gas into electricity, we have developed Mg2(Si1-xSnx) thermoelectric materials with high thermoelectric performance. The performance is evaluated with the dimensionless figure of merit (ZT), and the ZT has been improved through the development of the fabrication process and the investigation of the optimum composition and dopant element. A novel liquid-solid reaction synthesis method incorporating hot-pressing for the sample fabrication was effective in reducing the thermal conductivity. The n-type Mg2(Si0.50Sn0.50) doped with Sb attained a high ZT of 1.1 at 620 K. The p-type Mg2(Si0.25Sn0.75) doped with Li and Ag simultaneously achieved a ZT of 0.3 at 600 K. The effective maximum power of n-type thermoelectric element and that of p-type were calculated with the thermoelectromotive force and the mean resistivity.
2015-04-14
Technical Paper
2015-01-0341
Georg Rauch, Johannes Lutz, Martin Werner, Sagar Gurwara, Peter Steinberg
For solving problems in the field of engine heat up and thermal deformation of an engine, transient CHT analysis has gained high importance. The transient results make it possible to identify the amount of heat and its specific transfer region. Furthermore, the transient temperature profiles are used to generate the deformation fields which are crucial for friction calculations. Despite these useful applications transient CHT is avoided due to the large computational resources. This paper introduces an innovative approach which uses the synergy effect of 1D and 3D simulation in order to bring down modeling and simulation time. At the same time the methodology sustains the spatial resolution of a 3D model. This goal is reached by reducing the 3D fluid side with its time consuming continuity, momentum, energy and turbulence equations to a simple but precise 1D model. The structure stays in the 3D manner.
2015-04-14
Technical Paper
2015-01-0361
Yang Zou, Pega Hrnjak
Although refrigerant maldistribution among parallel microchannel tubes is mainly caused by phase separation of vapor and liquid in the header, it is also affected by pressure drop in the header. This study experimentally investigates the pressure drop of single-phase and two-phase R134a flow in the vertical header of a multi-pass microchannel heat exchanger. R134a is circulated into the transparent header through multi-parallel microchannel tubes in the bottom pass and exits through multi-parallel microchannel tubes in the top pass representing the flow in the heat pump mode of a reversible system. The pressure drop in the vertical header causes the top tube has lower mass flow rate than the lower tubes for both single-phase and two-phase flow. The overall pressure drop in the header includes four components: acceleration, gravitation, friction, and minor pressure drop due to microchannel tube protrusion.
2015-04-14
Technical Paper
2015-01-1703
John D. Bullough
Assessing the safety impacts of vehicle forward lighting is a challenge because crash data do not always contain details necessary to ascertain the role, if any, of lighting in crashes. The present paper will describe several approaches to evaluating the safety impacts of lighting using naturalistic driving data. Driving behavioral data and records of near-miss incidents might provide new opportunities to understand how forward lighting improves traffic safety.
2015-04-14
Technical Paper
2015-01-1254
Daishi Takahashi, Koichi Nakata, Yasushi Yoshihara, Yukinori OHTA, Hiroyuki Nishiura
In recent years, enhancing the engine thermal efficiency is strongly required. The current gasoline engine for hybrid vehicles has Atkinson cycle with high expansion ratio and cooled exhaust gas recirculation (EGR) system. The technologies contribute to raise the brake engine thermal efficiency more than 38%. It will be required that the engine thermal efficiency exceeds 40% in the near future. To enhance the engine thermal efficiency, it is essential to improve the engine anti-knock quality and to decrease the engine cooling heat loss. Therefore the cooled EGR technologies, which lead to reduce engine heat cooling loss and improve the anti-knock quality, are focused on. This paper describes that the technologies for enhancing the engine combustion technology such as high tumble which leads to the engine thermal efficiency of 40%.
2015-04-14
Technical Paper
2015-01-1653
Kenji Matsumoto, Hironori Harada, Hiroyoshi Taniguchi, Naoki Ito
We cooled pistons for car engines with a heat pipe. This improved the compression ratio and suppresses deformation. Because of the structural characteristics of heat pipes, however, the flow of gas and liquid is disturbed by vibration and the thermal conductivity becomes excessively low. As a result, heat pipes have not been used for cooling engines. We investigated the application of heat pipes to engine pistons by 1) changing the μ value in the pipe, and 2) inducing self-oscillation in vibration during high-speed reciprocation to control the two-layer flow of gas and liquid and ensure a high heat transfer coefficient without decreasing the amount of heat transport. We achieved these by developing an original heat pipe having a unique structure and experimented, determining its heat transfer coefficient using a high-speed reciprocating test apparatus. The heat pipe has gates installed inside to control the flow of gas and liquid during reciprocation.
2015-04-14
Technical Paper
2015-01-1711
Christian Hainzlmaier PhD, Alejandro S. Regueiro, Marvin Lappe
Hybrid- and Electric Vehicles have a heat deficit due to frequent operation of the engine in high efficiency regions or during pure electric driving where the engine as a heat source is not available. Especially for the conditioning of the cabin, additional heat sources are necessary to ensure comfort & safety. In order to maximize the electric driving range, and improve fuel efficiency, it is important to combine a fast, efficient and safe generation of heat, with a minimum drain from the traction battery. Webasto went about this challenge and developed the new Webasto High Voltage Heater (HVH) based on a new and patented heat layer technology. This paper explains the design concept and results of the novel clean sheet research and development approach taken to achieve the project goals.
2015-04-14
Technical Paper
2015-01-0661
Jianwang Shao, Xian Wu, Na Wei, Ding Wang, Guoming Deng, Ming Xu
An increasing demand for vehicle noise control has been proposed and at the same time, vehicle weight and fuel economy have become critical for the automotive industry. The methodology of statistical energy analysis (SEA) is used to balance both light weight and high noise insulation performance. In this paper, the vehicle dash and floor sound package systems, which are two of the major paths for vehicle interior noise, are studied and optimized by CAE and testing technology. Two types of sound package which are the conventional insulation system and the lightweight one are chosen for the vehicle dash and floor system. The vehicle dash and floor systems are modeled by SEA and the transmission loss (TL) of the dash and floor system is analyzed, respectively. Several influence factors of the TL are also analyzed, such as sound package coverage, the leaks, etc.
2015-04-14
Technical Paper
2015-01-0747
Aimin Du, Zhongpan ZHU, Chuanchuan Chu, Mengmeng Li
The research on intake, injection and mixture formation process of some gasoline direct injection engine is studied by using the CFD simulation technique. The effects of spray hole layout and injection strategy on mixture quality is also analyzed. Results show that the mixture quality can be improved with appropriate orifice layout. Using two-stage injection under condition of full load at low speed, compared to one injection, the fuel quantity impinging to wall is reduced and the cylinder turbulent kinetic energy is increased. In addition, the concentration of mixture near the spark plug is increased, which is beneficial to ignition. With more appropriate injection timing and injection ratio, the quality of mixture will be better. During cold start processes, the wallfilm can be reduced with appropriate injection timing. During hot start processes, the quality of mixture is declined with later injection timing.
2015-04-14
Technical Paper
2015-01-0721
Li Lu, Stacey Raines, Sean West, Jane Zhou, Paul Hoke
Traditionally, knee air bags (KAB) are made of a fabric consisting of nylon or polyester. More recently, Ford has developed an injection molded air bag system which can be integrated as a bladder that sandwiches between the glove box outer and inner doors. This new system is smaller and lighter. It also improves passenger’s safety numbers while increasing the roominess and other comfort features inside the cabin. The patented technology allows positioning of airbags in new locations of the vehicle, thus giving more freedom to the designers. The first application of this technology will be in all new Ford Mustang. It is a challenge to design, test and evaluate the performance of the above mentioned system when there is no benchmark to compare the technology against. A CAE driven design methodology was chosen instead. This method gave engineers the ability to use an iterative approach to designing and analytically proving the capability of the system.
2015-04-14
Technical Paper
2015-01-1712
Ram Vijayagopal, Aymeric Rousseau
This study looks at the impact of TEGs have on different types of light duty vehicles. UDDS, Highway and Combined 2 cycle procedures are used to evaluate the fuel economy benefits in these vehicles. These fuel economy benefits are then translated to gasoline savings and net present value of the monetary benefits. Previous studies had used TEG models that depend on exhaust flow traces recorded from the test bench. A better TEG model is developed which can estimate exhaust mass flow, and respond to variations in the exhaust flow. This model can also predict the temperature variations on the hot and cold side of the TEG modules. Better TEG modules are also modelled based on the published data from General Motors (GM). The heat dissipation through the TEG between the source and sink is modelled, but various other losses like contact losses or thermal losses within the TEG are not modelled.
2015-04-14
Technical Paper
2015-01-0350
Jing Cai, Gangfeng Tan
Thermoelectric power generation could achieve the recovery of engine exhaust waste heat. For the conventional scheme, the hot-end of the thermoelectric module is connected with the exhaust pipe, while the cold-end is cooled through the engine cooling cycle. The variation of engine operating conditions brings the instability of the hot-end temperature, which affects the power generation performance of thermoelectric materials and increases the damage risk to the thermoelectric materials caused by the high temperature. This research adopts the heat transfer oil circulation as the intermediate fluid to absorb the dynamic heat flux of the engine exhaust so as to release the heat steadily to the hot-end of the thermoelectric module. The thermal characteristics of the target diesel engine exhaust gas are evaluated based on the experimental data firstly.
2015-04-14
Technical Paper
2015-01-1392
Se Jin Park, Seung Nam Min, Murali Subramaniyam, Heeran Lee, Yu Kyung Shin, Chang Hee Jang, Soon Hyun Hwang
Driving postures is essential for evaluation of a driver workspace and also for improved seat design comfort. Data on occupant posture and body dimensions is gathered widely using portable coordinate measurement equipment, optical motion capture equipment, infrared depth sensor, and posture monitoring system. Nowadays, a number of 3D scanners are available on the market, which mainly used to enable anthropometry in an entirely new way. This study captures the comfortable driving postures for Koreans using 3D scanning measuring techniques. Subjects consisted of twenty healthy individuals (10 males and 10 females) ranging in age from 20 to 40 years and were carefully selected to include in three different weight groups (> 59 kg, 60 ~ 79 kg and < 80 kg). Driving postures were captured using a handheld portable 3D scanner (model: Artec LTM). A total of 18 land markers were attached (car seat: 9 markers; subject: 9 markers).
2015-04-14
Technical Paper
2015-01-0360
Maryline Leriche, Wolfgang Roessner, Heinrich Reister, Bernhard Weigand
An accurate model to predict the formation of fogging and defogging which occurs for low windshield temperatures is helpful for designing the air-conditioning system in the car. Using a multiphase flow approach and additional user-defined functions within a commercial CFD-software (STAR-CCM+), a model which is able to calculate the amount of water droplets on the windshield from condensation and which causes the fogging is set up. Different parameters like relative humidity, air temperature, mass flow rate and droplet distributions are considered. Because of the condition of the windshield’s surface, the condensation occurs as tiny droplets with different sizes. The distribution of these very small droplets must be obtained to estimate numerically the heat transfer coefficient during the condensation process to predict the defogging time.
2015-04-14
Technical Paper
2015-01-1341
Hisaki Sugaya, Yoshiyuki Tosa, Kazuo Imura, Hiroyuki Mae
When airbags deploy they break a plastic tear part of the instrument panel. Timing and the tear fracture process change the airbag’s deployment behavior. The tear fracture process is dependent on the plastic’s temperature. We developed a tear fracture simulation . Because the tear line is composed of 1mm width and 0.5mm-3.0mm flute thickness, simulating the tear fracture process is difficult, even using two models: airbag deployment, and plastic fracture. Thickness determines the tear fracture. The strain distribution of its parts should be predicted accurately. The tear fracture using solid mesh, which is 0.1mm mesh pitch, is predictable. Although it is a very complicated model and has a high computation cost, it is not applicable to the mass production development. We increase the accuracy of the tear fracture process prediction using the shell mesh, which is applicable to the mass production development.
2015-04-14
Technical Paper
2015-01-1391
Scott Allen Ziolek, Joshua Pryor, Tony Schwenn, Adam Steinman
Optimizing climate seat systems requires increased complexity in seat design which in turn is driving a need for more detailed thermal simulation methods. This paper presents the model development considerations and results of a thermal simulation study aimed at improving the thermal seat comfort experience of Hyundai-Kia’s heated seating systems.
2015-04-14
Technical Paper
2015-01-1603
Ahmed Abdel-Rehim
As the world is going through an evolutionary development in most of the science fields, there is an essential and exceptional demand for higher efficiency power generators to recover the thermal losses. Recently thermoelectric materials have attracted extensive attention for this purpose. The recent advancement in nanotechnology has a remarkable impact on thermoelectric materials development. This resulted in nano structured materials whose thermoelectric properties exhibit a great challenge to its bulk form, such as Silicon nanowires (SiNWs). Silicon nanowires are promising thermoelectric materials as they offer large reductions in thermal conductivity over bulk Si without significant decrease in the electrical conductivity. In the present work silicon nanowires have been implemented in fabricating a thermoelectric device which can be employed in different applications, such as engines, to recover part of the energy lost in these applications.
2015-04-14
Technical Paper
2015-01-1656
Lisa Henriksson, Peter Gullberg, Erik Dahl, Lennart Lofdahl
For some vehicle segments the cooling demand is increasing as a result of increased engine power or introduction of different systems, for example EGR, CAC, WHR. To be able to fulfil the increased cooling demand an increased efficiency of the cooling device or an increased cooling package are required. Due to limitations of space at the front of the vehicle, behind the grill, alternative positions of extra heat exchangers have to be evaluated. Common for most of these positions is that the oncoming airflow is not necessarily perpendicular to the heat exchanger core. Evaluation of inclined airflows relative to the heat exchanger must therefore be performed. This article presents CFD simulations on one period of a louvered fin of compact louvered fin heat exchangers, where the incoming airflow was inclined relative to the heat exchanger core.
2015-04-14
Technical Paper
2015-01-1649
Kenji Matsumoto, Atsushi Takahashi, tsutomu inoue
Efficient piston cooling methods provide means for fuel-efficiency and environmental compatibility by improving the compression ratio and suppressing the deformation of pistons. Thermal conductivity improves by using heat pipes in computers and air conditioners. However, heat pipes generally used have not been used for the cooling of engines because the flow of gas and liquid is disturbed by vibration and the thermal conductivity becomes excessively low. We developed an original heat pipe and conducted an experiment to determine its heat transfer coefficient using a high-speed reciprocating test apparatus. Although the test was based on a single heat pipe unit, we succeeded in improving the heat transfer coefficient during high-speed reciprocation by a factor of 6 compared to the heat transfer coefficient at standstill.
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