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Viewing 151 to 180 of 10086
2015-04-14
Technical Paper
2015-01-1658
Xi Luo, Xin Yu, Marcis Jansons
Abstract As engine efficiency targets continue to rise, additional improvements must consider reduction of heat transfer losses. The development of advanced heat transfer models and realistic boundary conditions for simulation based engine design both require accurate in-cylinder wall temperature measurements. A novel dual wavelength infrared diagnostic has been developed to measure in-cylinder surface temperatures with high temporal resolution. The diagnostic has the capability to measure low amplitude, high frequency temperature variations, such as those occurring during the gas exchange process. The dual wavelength ratio method has the benefit of correcting for background scattering reflections and the emission from the optical window itself. The assumption that background effects are relatively constant during an engine cycle is shown to be valid over a range of intake conditions during motoring.
2015-04-14
Technical Paper
2015-01-1653
Kenji Matsumoto, Hironori Harada, Hiroyoshi Taniguchi, Naoki Ito
Abstract Car engine piston cooling is an important technology for improving the compression ratio and suppressing the deformation of pistons. It is well known that thermal conductivity improves dramatically through the use of heat pipes in computers and air conditioners. However, the heat pipes in general use 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 therefore developed an original heat pipe and conducted an experiment to determine its heat transfer coefficient using a high-speed reciprocation testing 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 1.6 compared to the heat transfer coefficient at standstill. This report describes the observed characteristics and the method of verification.
2015-04-14
Technical Paper
2015-01-1649
Kenji Matsumoto, Atsushi Takahashi, Tsutomu Inoue
Abstract In our preceding report [1], we showed that the thermal conductivity of a heat pipe dramatically improves during high-speed reciprocation. However, this cooling method has rarely been applied to car engine pistons because the thermal conductivity of commercially available heat pipes does not increase easily even if the pipe is subjected to high-speed reciprocation. In consideration of the data from our preceding report, we decided to investigate heat pipe designs for car engine pistons, propose an optimum design, and conduct thermal analysis of the design. As a result, we found that it is possible to transport heat from the central piston head area, where cooling is most needed, to the piston skirt area, suggesting the possibility of efficient cooling.
2015-04-14
Technical Paper
2015-01-1650
Azmi Osman, Mohd Asmu'i Hussin, Shaiful Fadzil Zainal Abidin
Abstract The drive to reduce CO2 and fuel consumption from passenger cars requires improvements from various subsystems. In particular, the ever growing importance of effective and efficient thermal management will no doubt benefit the quest for more efficient vehicle. While many established automakers have decided to increase the sophistications of the engine cooling circuits through electronics, the increase in complexity and costs are still not desirable especially for A and B passenger car segments. With this in mind, simple mechanical based cooling systems with enhanced functionalities are in high demand. To meet such demand, a simplified engine split cooling circuit previously proposed, simulated and reported seems to be promising. To further verify the indicated advantages, a prototype unit was built and physically tested using a dynamometer with motoring capability.
2015-04-14
Technical Paper
2015-01-1712
Ram Vijayagopal, Aymeric Rousseau
Abstract Thermoelectric generators (TEGs) can be used for a variety of applications in automobiles. There is a lot of interest in using them for waste heat recovery from a fuel economy point of view. This paper examines the potential of TEGs to provide cost-effective improvements in the fuel economy of conventional vehicles and hybrid electric vehicles (HEVs). Simulation analysis is used to quantify fuel economy benefits. The paper explains how a TEG is used in a vehicle and explores the idea of improving the TEG design by introducing a thermal reservoir in the TEG model to improve the waste heat recovery. An effort is made to identify the technological and economic barriers (and their thresholds) that could prevent TEGs from becoming an acceptable means of waste heat recovery in automobiles.
2015-04-14
Technical Paper
2015-01-1660
Jose Ramon Serrano, Francisco Jose Arnau, Jaime Martin, Manuel Hernandez, Benoit Lombard
Abstract This paper presents an experimental analysis on the effect of thermal insulation of engine internal walls on the performance and emissions of a heavy-duty diesel engine. Some parts of the engine, like pistons, cylinder head and exhaust manifold were thermally insulated from gas contact side in order to reduce heat losses through the walls. Each component has been analyzed, independently, and in combination with others. The results have been compared with that of the original engine configuration. The analysis focuses on NOx and, smoke emissions along with brake specific fuel consumption. In order to take advantage of the engine insulation, an optimization of the air management and injection settings was finally performed, which provided the best combination for each engine configuration.
2015-04-14
Technical Paper
2015-01-1663
Prafulla P Ghare, Hemant Khalane, Udaysingh Wakhure, Tushar Khobragade, Sandip Chaudhari, Atul Jahirabadkar
Abstract As one of the most complicated parts of an internal combustion Engine, cylinder head is directly exposed to high combustion pressures and temperatures. Cooling must be provided for the heated surfaces to avoid overheating. However over-cooling will cause lower overall efficiency and high emission. Therefore, an optimal design of the cooling system is required to maintain trouble-free operation of engine. For single cylinder naturally aspirated Compression Ignition (CI) engines, on account of space restrictions, designing of cooling jacket is very critical. Engineers invest a large amount of time and serious effort to optimize the flow through engine cooling jacket with limited detailed information of conducting flow and heat transfer. This paper therefore, investigates cooling performance of a single cylinder 510cc production diesel engine.
2015-04-14
Technical Paper
2015-01-1472
Roberto Arienti, Carlo Cantoni, Massimiliano Gobbi, Giampiero Mastinu, Mario Pennati, Giorgio Previati
Abstract The lightweight seat of a high performance car is designed taking into account a rear impact, i.e. the crash due to an impulse applied from the rear. The basic parameters of the seat structure are derived resorting to simulations of a crash with a test dummy positioned on the seat. The simulations provide the forces acting at the seat structure, in particular the forces applied at the joint between the seat cushion and the seat backrest are taken into account. Such a joint is simulated as a plastic hinge and dissipates some of the crash energy. The simulations are validated by means of indoor tests with satisfactory results. A tool has been developed for the preliminary design of lightweight seats for high performance cars.
2015-04-14
Technical Paper
2015-01-0327
Elizabeth M. Patterson, Iman Goldasteh, Salamah Maaita
Abstract Recent progress in computer-aided engineering (CAE) has made it possible to model complex interdisciplinary multiphysics analyses. This paper investigated the sequential coupled thermal-structural analysis by examining the associated thermal stresses under simulated operational conditions close to the real situation. An evaluation of exhaust muffler strain due to thermal stresses was made by coupling Star-CCM+ CFD software and ABAQUS FEM structural analysis software. The study was made to evaluate discovered muffler durability test failure and to develop a countermeasure design. Failure of the muffler internal pipe was discovered after heat cycle durability testing. The internal pipe had broken into two pieces. In the first step, CFD analysis was done by thermo-flow simulation to determine the resulting heat distribution on the muffler assembly when subjected to the prescribed peak duty cycle temperature.
2015-04-14
Technical Paper
2015-01-0248
Hiroyasu Baba, Koji Kawasaki, Hideomi Kawachi
Abstract We have developed Li-ion battery heating system which is direct resistance heating for hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV) and electric vehicles (EV) by use of an inverter and a motor. One relay is added between a positive terminal of Li-ion battery and one-phase (e.g. U-phase) of a three-phase motor. When additional relay is turned on, the motor coils, IGBTs (Insulated-gate bipolar transistor) and diodes in the inverter and a smoothing capacitor for the inverter constitute buck-boost DC to DC converter. IGBTs are controlled to repeat charging and discharging between the battery and the smoothing capacitor. We made a system prototype and examined battery heating capability. And also we optimized charging and discharging frequency from impedance and current to improve heat generation. This method can increase battery temperature from −20 degrees C to 0 degrees C in 5 minutes and can extend EV driving range.
2015-04-14
Technical Paper
2015-01-0352
Kuo-Huey Chen, Jeffrey Bozeman, Mingyu Wang, Debashis Ghosh, Edward Wolfe, Sourav Chowdhury
Abstract The present paper reports on a study of the HVAC energy usage for an EREV (extended range electric vehicle) implementation of a localized cooling/heating system. Components in the localized system use thermoelectric (TE) devices to target the occupant's chest, face, lap and foot areas. A novel contact TE seat was integrated into the system. Human subject comfort rides and a thermal manikin in the tunnel were used to establish equivalent comfort for the baseline and localized system. The tunnel test results indicate that, with the localized system, HVAC energy savings of 37% are achieved for cooling conditions (ambient conditions greater than 10 °C) and 38% for heating conditions (ambient conditions less than 10 °C), respectively based on an annualized ambient and vehicle occupancy weighted method. The driving range extension for an electric vehicle was also estimated based on the HVAC energy saving.
2015-04-14
Journal Article
2015-01-0149
Can Wang, Gangfeng Tan, Xuexun Guo, Zhewen Tian, Zhanwei Tian, Jiafan Li
Abstract In summer, when vehicle parks in direct sunlight, the closed cabin temperature would rise sharply, which affects the occupants step-in-car comfort Solar powered vehicle parking ventilation system adopts the solar energy to drive the original ventilator. Thus, the cabin temperature could be dramatically decreased and the riding comfort could be also improved. This research analyzed the modified crew cabin thermal transfer model. Then the performance of the solar powered ventilation system is analyzed and optimized combined with the power supply characteristics of the photovoltaic element. The storage and reuse of the solar power is achieved on condition that the cabin temperature could be steadily controlled. The research shows that, the internal temperature is mainly affected by the solar radiation intensity and the environment temperature.
2015-04-14
Journal Article
2015-01-0254
Chunjing Lin, Sichuan Xu, Zhao Li, Guofeng Chang
Abstract A passive thermal management system (TMS) using composite phase change material (PCM) for large-capacity, rectangular lithium-ion batteries is designed. A battery module consisting of six Li-ion cells connected in series was investigated as a basic unit. The passive TMS for the module has three configurations according to the contact area between cells and the composite PCM, i.e., surrounding, front-contacted and side-contacted schemes. Firstly, heat generation rate of the battery cell was calculated using the Bernardi equation based on experimentally measured heat source terms (i.e. the internal resistance and the entropy coefficient). Physical and thermal properties such as density, phase change temperature, latent heat and thermal conductivity of the composite PCM were also obtained by experimental methods. Thereafter, thermal response of the battery modules with the three TMS configurations was simulated using 3D finite element analysis (FEA) modeling in ANSYS Fluent.
2015-04-14
Journal Article
2015-01-1695
Satoki Tada, Takahiro Nagai, Naoki Shioda, Hirofumi Fujiu, Shunji Kumagai, Hideaki Abe, Yukihiro Isoda, Yoshikazu Shinohara
Abstract 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 hotpressing 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
Journal Article
2015-01-1184
Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
Abstract The performance, life cycle cost, and safety of electric and hybrid electric vehicles (EVs and HEVs) depend strongly on their energy storage system. Advanced batteries such as lithium-ion (Li-ion) polymer batteries are quite viable options for storing energy in EVs and HEVs. In addition, thermal management is essential for achieving the desired performance and life cycle from a particular battery. Therefore, to design a thermal management system, a designer must study the thermal characteristics of batteries. The thermal characteristics that are needed include the surface temperature distribution, heat flux, and the heat generation from batteries under various charge/discharge profiles. Therefore, in the first part of the research, surface temperature distribution from a lithium-ion pouch cell (20Ah capacity) is studied under different discharge rates of 1C, 2C, 3C, and 4C.
2015-04-14
Technical Paper
2015-01-1711
Christian Hainzlmaier, Alejandro S. Regueiro, Marvin Lappe
Abstract 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 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
2015-01-0878
Guanzhang He, Hui Xie
Abstract The performance of three different electric turbo-compounding systems under both steady and driving cycle condition is investigated in this paper. Three configurations studied in this paper are serial turbo-compounding, parallel turbo-compounding and electric assisted turbo-compounding. The electric power, global gain of the whole system (engine and power turbine) under steady operating condition is firstly studied. Then investigation under three different driving cycles is conducted. Items including fuel consumption, engine operating point distribution and transient response performance are analyzed among which the second item is done based on statistic method combined with the results obtained under steady operating conditions. Study under steady condition indicates that electric assisted turbo-compounding system is the best choice compared with the other two systems.
2015-04-14
Technical Paper
2015-01-1254
Daishi Takahashi, Koichi Nakata, Yasushi Yoshihara, Yukinori Ohta, Hiroyuki Nishiura
Abstract In recent years, enhancing engine thermal efficiency is strongly required. Since the maximum engine thermal efficiency is especially important for HVs, the technologies for improving engine thermal efficiency have been developed. The current gasoline engines for hybrid vehicles have Atkinson cycle with high expansion ratio and cooled exhaust gas recirculation (EGR) system. These technologies contribute to raise the brake engine thermal efficiency to more than 38%.In the near future the consumers demand will push the limit to 40% thermal efficiency. To enhance engine thermal efficiency, it is essential to improve the engine anti-knock quality and to decrease the engine cooling heat loss. To comply with improving the anti-knock quality and decreasing the cooling heat loss, it is known that the cooled EGR is an effective way.
2015-04-14
Technical Paper
2015-01-1753
Mario Vila Millan, Stephen Samuel
Abstract Stringent emission norms introduced by the legislators over the decades has forced automotive manufacturers to improve the fuel economy and emission levels of their engines continuously. Therefore, the emission levels of modern engines are significantly lower than pre-1990 engines. However, the improvement in fuel economy is marginal when compared to that of emission levels. For example, approximately 30% of total energy in the fuel is being wasted through the cooling systems in the modern engines. Therefore, thermal management systems are being developed to reduce these losses and offer new opportunities for improving the fuel economy of the vehicles. One of the new emerging technologies for thermal management is the use of nanofluids as coolant. Nanofluids are a mixture of nano-sized particles added to a base fluid to improve its thermal characteristics.
2015-04-14
Technical Paper
2015-01-1705
Miguel Hurtado, Amine Taleb-Bendiab, Julien Moizard, Patrice M. Reilhac, Heinz Mattern
Abstract Current market trend indicates an increased interest in replacing mirrors by camera monitor systems (CMS) to reduce CO2 emissions and to improve visibility of surrounding environment to the driver. A CMS is an advanced system composed of an electronic imager, a display, and an intelligent electronic control unit intended to provide at least the same level of functionality of legally prescribed mirrors. A CMS must also take into consideration several factors in the designed system to satisfy an overall system magnification and system resolution. Some factors pertain to the camera, and display inside the cockpit, but some other are related to the physical constraints of the human operator, i.e. visual acuity, height, etc. In this paper, we demonstrate that there exists a fundamental nonlinear equation for a given CMS encompassing factors that influence the performance of the system.
2015-04-14
Journal Article
2015-01-0326
Takuya Yamaguchi, Yuzo Aoyagi, Noboru Uchida, Akira Fukunaga, Masayuki Kobayashi, Takayuki Adachi, Munemasa Hashimoto
Abstract In heavy duty diesel engines, the waste heat recovery has attracted much attention as one of the technologies to improve fuel economy further. In this study, the available energy of the waste heat from a high boosted 6-cylinder heavy duty diesel engine which is equipped with a high pressure loop EGR system (HPL-EGR system) and low pressure loop EGR system (LPL-EGR system) was evaluated based on the second law of thermodynamics. The maximum potential of the waste heat recovery for improvement in brake thermal efficiency and the effect of the Rankine combined cycle on fuel economy were estimated for each single-stage turbocharging system (single-stage system) and 2-stage turbocharging system (2-stage system).
2015-04-14
Journal Article
2015-01-0782
Philipp Huegel, Heiko Kubach, Thomas Koch, Amin Velji
Abstract In this work, heat loss was investigated in homogeneous and stratified DI-SI operation mode in a single cylinder research engine. Several thermocouples were adapted to the combustion chamber surfaces. The crank angle resolved temperature oscillations at the cylinder head and piston surface could thereby be measured in homogeneous and stratified operation mode. A grasshopper linkage was designed and adapted to the engine, to transfer the piston signals to the data acquisition device. The design of the experimental apparatus is described briefly. For both operation modes the average steady-state temperatures of the combustion chamber surfaces were compared. The temperature distribution along the individual sensor positions at the cylinder head and piston surface are shown. Furthermore, the curves of the crank angle resolved temperature oscillations in stratified and homogeneous operation mode were compared.
2015-04-14
Journal Article
2015-01-0339
Aimon Allouache, Smith Leggett, Matthew J. Hall, Ming Tu, Chad Baker, Haiyan Fateh
Abstract The performance of an organic Rankine cycle (ORC) that recovers heat from the exhaust of a heavy-duty diesel engine was simulated. The work was an extension of a prior study that simulated the performance of an experimental ORC system developed and tested at Oak Ridge National laboratory (ORNL). The experimental data were used to set model parameters and validate the results of that simulation. For the current study the model was adapted to consider a 15 liter turbocharged engine versus the original 1.9 liter light-duty automotive turbodiesel studied by ORNL. Exhaust flow rate and temperature data for the heavy-duty engine were obtained from Southwest Research Institute (SwRI) for a range of steady-state engine speeds and loads without EGR. Because of the considerably higher exhaust gas flow rates of the heavy-duty engine, relative to the engine tested by ORNL, a different heat exchanger type was considered in order to keep exhaust pressure drop within practical bounds.
2015-04-14
Journal Article
2015-01-0342
Forrest Jehlik, Eric Wood, Jeffrey Gonder, Sean Lopp
Abstract It is widely understood that cold ambient temperatures increase vehicle fuel consumption due to heat transfer losses, increased friction (increased viscosity lubricants), and enrichment strategies (accelerated catalyst heating). However, relatively little effort has been dedicated to thoroughly quantifying these impacts across a large set of real world drive cycle data and ambient conditions. This work leverages experimental dynamometer vehicle data collected under various drive cycles and ambient conditions to develop a simplified modeling framework for quantifying thermal effects on vehicle energy consumption. These models are applied over a wide array of real-world usage profiles and typical meteorological data to develop estimates of in-use fuel economy. The paper concludes with a discussion of how this integrated testing/modeling approach may be applied to quantify real-world, off-cycle fuel economy benefits of various technologies.
2015-04-14
Journal Article
2015-01-0357
Huize Li, Predrag Hrnjak
Abstract This paper presents a method of utilizing infrared images to quantify the distribution of liquid refrigerant mass flow rate in microchannel heat exchangers, which are widely used in automobile air conditioning systems. In order to achieve quantification, a relationship is built between the liquid mass flow rate through each microchannel tube and the corresponding air side capacity calculated from the infrared measurement of the wall temperature. After being implemented in a heat exchanger model, the quantification method is validated against experimental data. This method can be used for several types of heat exchangers and it can be applied to various heat exchanger designs.
2015-04-14
Journal Article
2015-01-0359
Satoki Uematsu, Toshiyuki Uehara, Toshiya Uchida, Gursaran D. Mathur
Abstract In last 10 years or so, a number of OEMs are designing vehicles with start-stop function to save energy and to reduce pollution. For these systems, the situations in which air-conditioning systems are used have been changing with a significant increase in adoption of idle-time reduction systems (no idling-system). Blower fan remains operating at idle condition while compressor stops in most cases for these systems. In this case, the air temperature at the vent outlets increases. The increase in the air temperature under range of thermal boundary conditions around the evaporator causes a concern of odor to occur. This paper describes and explains experimental studies on changes in heat and humidity at the air outlets according to the switching operation of compressor and root cause analyses of odor coming from air-conditioning system for vehicles with start-stop function.
2015-04-14
Journal Article
2015-01-0371
Rupesh Sonu Kakade, Prashant Mer
Abstract The human thermal comfort, which has been a subject of extensive research, is a principal objective of the automotive climate control system. Applying the results of research studies to the practical problems require quantitative information of the thermal environment in the passenger compartment of a vehicle. The exposure to solar radiation is known to alter the thermal environment in the passenger compartment. A photovoltaic-cell based sensor is commonly used in the automotive climate control system to measure the solar radiation exposure of the passenger compartment of a vehicle. The erroneous information from a sensor however can cause thermal discomfort to the occupants. The erroneous measurement can be due to physical or environmental parameters. Shading of a solar sensor due to the opaque vehicle body elements is one such environmental parameter that is known to give incorrect measurement.
2015-04-14
Journal Article
2015-01-0438
Ashley Lehman, Vesselin Stoilov, Andrzej Sobiesiak
Abstract This paper describes the application of the Fourier Amplitude Sensitivity Test (FAST) method [1] to investigate the effect of uncertainty in design parameters on the thermal system performance of vehicle underbody components. The results from this study will pinpoint the design parameters which offer the greatest opportunity for improvement of thermal system performance and reliability. In turn, this method can save engineering time and resources. An analytical model was developed for a vehicle underbody system consisting of a muffler, heat shield, and spare tire tub. The output from this model was defined as the temperature of the spare tire tub. The majority of the input parameters in this model deviate from their nominal values due to environmental factors, wear and ageing, and/or variation in the manufacturing process.
2015-04-14
Journal Article
2015-01-0441
Takashi Takiguchi, Yusuke Yano, Yasuhiro Takii, Nobuyuki Ohta
Abstract With demands for enhanced environmental performance such as fuel economy, the tendency has been to reduce the amount of wind introduced to the engine room to reduce drag. Meanwhile, exhaust gas temperatures are increasing in order to reduce emissions concentrations. As a result, the temperature environments for parts inside the engine room and underfloor parts are becoming harsher, and accurately understanding the temperature environments of parts is crucial in determining Engine room component layout during vehicle development and applying effective thermal countermeasures. Computational fluid dynamics (CFD) are effective for understanding complex phenomena such as heat generation and cooling. However, this paper reports the development of a method for accurately calculating the vehicle temperature distribution through identification from test results.
2015-04-14
Journal Article
2015-01-0440
Julio Carrera, Alfredo Navarro, Concepcion Paz, Alvaro Sanchez, Jacobo Porteiro
Recent emissions standards have become more restrictive in terms of CO2 and NOx reduction. This has been translated into higher EGR rates at higher exhaust gas temperatures with lower coolant flow rates for much longer lifetimes. In consequence, thermal load for EGR components, specially EGR coolers, has been increased and thermal fatigue durability is now a critical issue during the development. Consequently a new Thermo-Mechanical Analysis (TMA) procedure has been developed in order to calculate durability. The TMA calculation is based on a Computational Fluid Dynamics simulation (CFD) in which a boiling model is implemented for obtaining realistic temperature predictions of the metal parts exposed to possible local boiling. The FEM model has also been adjusted to capture the correct stress values by submodeling the critical areas. Life calculation is based on a Multiaxial Fatigue Model that has also been implemented in FEM software for node by node life calculation.
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