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Viewing 181 to 210 of 9836
2014-04-01
Technical Paper
2014-01-0684
B. Vasanth, Jose Bright, Pavan Reddy, Sathish Kumar S, Murali Govindarajalu
Abstract In an Automotive air conditioning system, the air flow distribution in the cabin from the HVAC (Heating, ventilation and air conditioning), ducts and outlets is evaluated by the velocity achieved at driver and passenger mannequin aim points. Multiple simulation iterations are being carried out before finalizing the design of HVAC panel duct and outlets until the target velocity is achieved. In this paper, a parametric modeling of the HVAC outlet is done which includes primary and secondary vane creation using CATIA. Java macro files are created for simulation runs in STAR CCM+. ISIGHT is used as an interface tool between CATIA and STARCCM+. The vane limits of outlet and the target velocity to be achieved at mannequin aim points are defined as the boundary conditions for the analysis. Based on the optimization technique and the number of iterations defined in ISIGHT, the vane angle model gets updated automatically in CATIA followed by the simulation runs in STARCCM+. Based on the results vane angle will get updated and the iterations continues automatically till the target velocity is met at the aim points.
2014-04-01
Technical Paper
2014-01-0680
Jason Aaron Lustbader, Cory Kreutzer, Matthew A. Jeffers, Steven Adelman, Skip Yeakel, Philip Brontz, Kurt Olson, James Ohlinger
Abstract Cab climate conditioning is one of the primary reasons for operating the main engine in a long-haul truck during driver rest periods. In the United States, sleeper cab trucks use approximately 667 million gallons of fuel annually for rest period idling. The U.S. Department of Energy's National Renewable Energy Laboratory's (NREL) CoolCab Project works closely with industry to design efficient thermal management systems for long-haul trucks that minimize engine idling and fuel use while maintaining occupant comfort. Heat transfer to the vehicle interior from opaque exterior surfaces is one of the major heat pathways that contribute to air conditioning loads during long-haul truck daytime rest period idling. To quantify the impact of paint color and the opportunity for advanced paints, NREL collaborated with Volvo Group North America, PPG Industries, and Dometic Environmental Corporation. Initial screening simulations using CoolCalc, NREL's rapid HVAC load estimation tool, showed promising air-conditioning load reductions due to paint color selection.
2014-04-01
Technical Paper
2014-01-0671
Can Yang, Hui Xie, Shengkai Zhou
Abstract The RCS (Rankine cycle system) used to recover the exhaust gas energy from internal combustion engines has been regarded as one of the most promising ways to achieve higher efficiency. However, it is a big challenge to keep the RCS still in good performance under variable driving cycle. This paper aims at revealing the reasons resulting in the low efficiency under driving cycle, comparing to that under steady-state condition. The dynamic operating process of the RCS under driving cycle is analyzed, and then the RCS applied on an 11.6L heavy duty diesel engine is modeled. Based on that, the dynamic performance of the RCS under an actual driving cycle is discussed. The results indicate that the average efficiency under a piece of Tianjin bus driving cycle is as low as 3.63%, which is less than half of that (7.77%) under the rated point (1300rpm and 50%load). The reasons leading to the low efficiency under driving cycle is interpreted from three aspects. Firstly, effects of the optimizing criterions are studied.
2014-04-01
Technical Paper
2014-01-0668
Armin Traussnig, Heinz Petutschnig, Andreas Ennemoser, Michael Stolz, Mauro Tizianel
Abstract In order to meet current and future emission and CO2 targets, an efficient vehicle thermal management system is one of the key factors in conventional as well as in electrified powertrains. Furthermore the increasing number of vehicle configurations leads to a high variability and degrees of freedom in possible system designs and the control thereof, which can only be handled by a comprehensive tool chain of vehicle system simulation and a generic control system architecture. The required model must comprise all relevant systems of the vehicle (control functionality, cooling system, lubrication system, engine, drive train, HV components etc.). For proper prediction with respect to energy consumption all interactions and interdependencies of those systems have to be taken into consideration, i.e. all energy fluxes (mechanical, hydraulically, electrical, thermal) have to be exchanged among the system boundaries accordingly. However, it is very important that the level of detail of the VTMS model fits to the current phase of the vehicle development process.
2014-04-01
Technical Paper
2014-01-0670
Chengyu Zhang, Ge-Qun Shu, Hua Tian, Haiqiao Wei, Guopeng Yu, Youcai Liang
Abstract This paper presents a model system TEG-DORC that employs thermoelectric generator (TEG) as a topping cycle integrated with a dual-loop organic Rankine bottoming cycle (DORC) to recover exhaust heat of internal combustion engine (ICE). The thermodynamic performance of TEG-DORC system is analyzed based on the first and second law of thermodynamics when system net output power Wnet, thermal efficiency ηth, exergy efficiency ηe and volumetric expansion ratio are chosen as objective functions. The model has many parameters that affect combined system performance such as TEG scale, evaporation pressure of high temperature ORC loop (HT loop) Pevp,HT, condensation temperature of HT loop Tcond,HT. It is suggested that HT loop has a vital influence on system performance. The results show that TEG-DORC system can significantly improve system performance, and system net output power gets maximum (30.69kW) when Tcond,HT is 370K and Pevp,HT is 4MPa, accordingly, the absolute effective thermal efficiency increases by 5.2%.
2014-04-01
Technical Paper
2014-01-0673
Charles Sprouse III, Christopher Depcik
Abstract Significant progress towards reducing diesel engine fuel consumption and emissions is possible through the simultaneous Waste Heat Recovery (WHR) and Particulate Matter (PM) filtration in a novel device described here as a Diesel Particulate Filter Heat Exchanger (DPFHX). This original device concept is based on the shell-and-tube heat exchanger geometry, where enlarged tubes contain DPF cores, allowing waste heat recovery from engine exhaust and allowing further energy capture from the exothermic PM regeneration event. The heat transferred to the working fluid on the shell side of the DPFHX becomes available for use in a secondary power cycle, which is an increasingly attractive method of boosting powertrain efficiency due to fuel savings of around 10 to 15%. Moreover, these fuel savings are proportional to the associated emissions reduction after a short warm-up period, with startup emissions relatively unchanged when implementing a WHR system. Due to the absence of prior DPFHX research and the unique heat transfer process present, this effort describes construction of a prototype DPFHX and subsequent WHR experiments in a single cylinder diesel engine test cell with a comparison between heat exchanger performance with and without DPF cores installed.
2014-04-01
Technical Paper
2014-01-0666
Michael Fritz, Frank Gauterin, Justus Wessling
Abstract Steadily rising energy prices and increasingly strict emissions legislation enforce the development of measures that increase efficiency of modern vehicles. An important contribution towards more efficient vehicles is the introduction of measures regarding auxiliary units. These measures increase the gross efficiency of a vehicle and therefore also the vehicle's range. Among the auxiliary power units of a vehicle like a long-haul truck, the refrigerant compressor generally consumes the biggest amount of energy. Therefore, it is reasonable to focus efficiency-increasing efforts on optimizing the A/C system. An important tool used in the development of optimization approaches is the simulation of the relevant systems. This allows a cost-optimized evaluation of the optimization approaches and also lets the engineer compare multiple variations of these approaches within a short period of time. For a significant evaluation of the potentials to be expected by implementation of different measures and variations optimizing the A/C system, it is necessary to simulate these under several climatic conditions.
2014-04-01
Technical Paper
2014-01-0658
Vinod Kumar Srinivasa, Renjith S, Biswadip Shome
Abstract Increasing demands on engine power to meet increased load carrying capacity and adherence to emission norms have necessitated the need to improve thermal management system of the vehicle. The efficiency of the vehicle cooling system strongly depends on the fan and fan-shroud design and, designing an optimum fan and fan-shroud has been a challenge for the designer. Computational Fluid Dynamics (CFD) techniques are being increasingly used to perform virtual tests to predict and optimize the performance of fan and fan-shroud assembly. However, these CFD based optimization are mostly based on a single performance parameter. In addition, the sequential choice of input parameters in such optimization exercise leads to a large number of CFD simulations that are required to optimize the performance over the complete range of design and operating envelope. As a result, the optimization is carried out over a limited range of design and operating envelope only. In this paper, a Design of Experiments (DoE) based CFD approach has been used to optimize the fan and fan-shroud design of a cooling pack system.
2014-04-01
Technical Paper
2014-01-0656
Alaa El-Sharkawy
Abstract Computational tools have been extensively applied to predict component temperatures before an actual vehicle is built for testing [1, 2, 3, 4, and 5]. This approach provides an estimate of component temperatures during a specific driving condition. The predicted component temperature is compared against acceptable temperature limits. If violations of the temperature limits are predicted, corrective actions will be applied. These corrective actions may include adding heat shields to the heat source or to the receiving components. Therefore, design changes are implemented based on the simulation results. Sensitivity analysis is the formal technique of determining most influential parameters in a system that affects its performance. Uncertainty analysis is the process of evaluating the deviation of the design from its intended design target. In the case of thermal protection, uncertainty analysis is applied in order to determine the variation of the calculated component temperature around its nominal value.
2014-04-01
Technical Paper
2014-01-0657
Fabien Rabeau, Sebastien Magand
Abstract Thermal management is a key issue to minimize fuel consumption while dealing with pollutant emissions. It paves the way for developing new methods and tools in order to assess the effects of warm up phase with different drivetrains architectures and to define the most suitable solution to manage oil and coolant temperatures. DEVICE (Downsized hybrid Diesel Engine for Very low fuel ConsumptIon and CO2 Emissions) project consists in designing hybrid powertrain to cut off significantly CO2 emissions. It combines a 2-cylinder engine with an electric motor and a 7-gear dual clutch transmission. Hybridization and downsizing offer a great improvement of fuel economy and it is valuable to study their effects on thermal management. Hence, a dedicated AMESim platform is developed to model the fluids temperatures as well as the energy balance changes due to the powertrain architecture. After using a 4-cylinder reference engine to validate the model, the warm up phase (comparing hot and cold start NEDC) leads to a 12% fuel consumption penalty with DEVICE powertrain.
2014-04-01
Technical Paper
2014-01-0650
Shi-Ing Chang, Iman Goldasteh, Salamah Maaita, Gursaran Mathur
Abstract The performance of an automobile engine depends on the adequate heat rejection through the radiator assembly. Despite of the existence of well-known theoretical models for various heat transfer applications, design of heat exchanger devices demands tremendous experimental work and effort. This study concerns the use of computational fluid dynamics (CFD) to analyze the heat transfer and fluid flow in finned tube heat exchangers which are widely used in automotive industries. Here, two different types of the finned tube heat exchangers were studied using the Star-CCM+ commercial CFD package. Because of the symmetric nature of the geometry, only a single fin was considered in simulations. Two different designs of finned tube heat exchanger were considered in the analysis and major attention was given to the fin configurations, louvers number and louvers angle. Although the contact surface of the fin to the coolant tube is different, the thermal performance was not affected under present steady state analysis.
2014-04-01
Technical Paper
2014-01-0647
Jiazhen Ling, Magnus Eisele, Hongtao Qiao, Vikrant Aute, Yunho Hwang, Reinhard Radermacher
Abstract As a potential replacement to traditional automotive R134a direct expansion (DX) systems, a secondary-loop system allows for the usage of flammable but low-GWP refrigerants such as propane (R290). However, as the secondary-loop system has an additional layer of thermal resistance, the cycle's transient behavior and cabin thermal comfort during pull-down and various driving cycles may be different from traditional DX systems. This paper presents a Modelica-based model to simulate both steady-state and transient operation of automotive secondary-loop systems. The model includes a lumped cabin component and a secondary-loop automotive air-conditioning system component. The air-conditioning system component consists of a condenser, a compressor, an expansion device, a coolant plate type heat exchanger, a coolant to air heat exchanger and a coolant pump. The developed model was validated against both steady-state and transient experimental data for an R290 secondary-loop system. The steady-state comparison demonstrates a 7.5% deviation of air-side COP compared to the experimental data.
2014-04-01
Technical Paper
2014-01-0651
Zun Wang, Jaehoon Han, Devadatta Mukutmoni
Abstract At the onset of soak, air and surface temperatures in an engine bay enclosure are elevated since temperature of heat sources are high while convective cooling is sharply reduced as a result of airflow being shut off from the inlet grilles of the vehicle leading to temperature spikes. Accurate simulation of this important thermal and flow regime that is natural convection driven, highly transient and complex is therefore very important. In this investigation, we simulate flow in the engine bay at the onset of soak with fixed thermal boundary conditions where the geometries representing the engine bay and components are simplified. Good agreement was observed with detailed experimental data available in references for both velocities and temperatures.
2014-04-01
Technical Paper
2014-01-0642
Kristian Haehndel, Angus Pere, Torsten Frank, Frieder Christel, Sylvester Abanteriba
Abstract As computational methodologies become more integrated into industrial vehicle pre-development processes the potential for high transient vehicle thermal simulations is evident. This can also been seen in conjunction with the strong rise in computing power, which ultimately has supported many automotive manufactures in attempting non-steady simulation conditions. The following investigation aims at exploring an efficient means of utilizing the new rise in computing resources by resolving high time-dependent boundary conditions through a series of averaging methodologies. Through understanding the sensitivities associated with dynamic component temperature changes, optimised boundary conditions can be implemented to dampen irrelevant input frequencies whilst maintaining thermally critical velocity gradients. A sub-module derived from real vehicle geometry was utilised to evaluate a series of alternative averaging schemes (consisting of steady-state CFD points) in comparison to full CFD transient conditions.
2014-04-01
Technical Paper
2014-01-0646
Kristian Haehndel, Anthony Jefferies, Markus Schlipf, Torsten Frank, Frieder Christel, Sylvester Abanteriba
Abstract At the rear of the vehicle an end acoustic silencer is attached to the exhaust system. This is primarily to reduce noise emissions for the benefit of passengers and bystanders. Due to the location of the end acoustic silencer conventional thermal protection methods (heat shields) through experimental means can not only be difficult to incorporate but also can be an inefficient and costly experience. Hence simulation methods may improve the development process by introducing methods of optimization in early phase vehicle design. A previous publication (Part 1) described a methodology of improving the surface temperatures prediction of general exhaust configurations. It was found in this initial study that simulation results for silencer configurations exhibited significant discrepancies in comparison to experimental data. This was mainly due to the inability to represent complex fluid flows through the components of the silencer, which was greatly simplified in the simulation models and software utilised.
2014-04-01
Technical Paper
2014-01-0350
Pankaj G. Bhirud, Shreyas Shingavi, Ajay Virmalwar
Abstract Ashcan contributes to the aesthetics and elegance of the vehicle interiors. It is used to store the ash. Generally the ashcan is fitted on the console of the car. The operational requirement of ashcan is to open with minimum force but not at very low accelerations experienced during the vehicle bump event. Also closing force should be comparatively higher. The closing of the ashcan lid should ensure positive locking, which may be achieved by using cam and follower locking mechanism. The other requirement is that it should be structurally durable enough to sustain the repetitive loading during its operation. Ashcan may undergo severe abusive loading during its operation. To simulate these operations and understand the physics of the problem, a multi-step non-linear analysis involving a complex contact situation is carried out. The scope of this paper is to explain the procedure of calculating the force required for closing and opening of the ashcan lid. The forces calculated using finite element analysis (F.E.A) are compared with physical test forces and the functionality failure is compared with field failure.
2014-04-01
Technical Paper
2014-01-0270
Rupesh Sonu Kakade, Prashant Mer
Abstract A human thermal comfort, which has been a subject of extensive research, is a principal objective of the climate control systems. Applying the results of research studies to practical problems requires quantitative information of the thermal environment parameters, such as the solar radiation. A photovoltaic-cell based sensor is commonly used in the automotive climate control systems for the measurement of solar radiation information. The erroneous information from the sensors can cause thermal discomfort. The erroneous measurement from sensors can be due to physical or environmental parameters. Shading of a solar sensor due to opaque vehicle body elements is one such environmental parameter that is known to give incorrect measurement. Analytical method that uses fundamental geometric principles is proposed to determine whether sensor is shaded, for a known location of the sun and for a given geometry of the vehicle passenger compartment. A corrective action to measured data when sensor is shaded that ensures thermal comfort is also presented.
2014-04-01
Technical Paper
2014-01-0013
Ravi Kiran Cheni, Chetan Prakash Jain, Revathy Muthiah, Srikanth Gomatam
Abstract Automotive OEMs quest for vehicle body light weighting, increase in Fuel efficiency along with significant cut in the emissions pose significant challenges. Apart from the effect on vehicle handling, the reduction of vehicle weight also results in additional general requirements for acoustic measures as it is an important aspect that contributes to the comfort and the sound quality image of the vehicle, thus posing a unique challenge to body designers and NVH experts. Due to these conflicting objectives, accurate identification along with knowledge of the transfer paths of vibrations and noise in the vehicle is needed to facilitate measures for booming noise dampening and vehicle structure vibration amplitude. This paper focuses on the application of a unique design and development of vehicle body structure anti-vibration dynamic damper (DD), unique in its aspect in controlling booming noise generated at a specific RPM range. Design methodology follows the concept of Mass-damper system on vehicle body or engine structure where panel with multi-degree of freedom vibrating at medium level frequency is transferred to damper which is vibrating at same resonant frequency in 180° opposite phase.
2014-04-01
Technical Paper
2014-01-0014
Changxin Wang, Deguang Fang, Fuxiang Guo
Abstract To find out the main excitation sources of a bus floor's vibration, modal analysis and spectral analysis were respectively performed in the paper. First we tested the vibration modal of the bus's floor under the full-load condition, and the first ten natural frequencies and vibration modes were obtained for the source identification of the bus floor's vibration. Second the vibration characteristic of the bus floor was measured in an on-road experiment. The acceleration sensors were arranged on the bus's floor and the possible excitation sources of the bus, which includes engine mounting system, driveline system, exhaust system, and wheels. Then the on-road experiment was carefully conducted on a highway under the four kinds of test condition: in-situ acceleration, uniform velocity (90km/h, 100km/h, 110km/h, 120km/h), uniform acceleration with top gear, and stall sliding condition with neutral gear. After that, by performing order tracking analysis and spectral analysis, the 1st order rotation frequency of the driveline and the 2nd order frequency of engine were identified to be the main cause of bus floor's vibration.
2014-04-01
Technical Paper
2014-01-0032
Sung Young Shin, Sang Dong Lee, Bong Chul Go
Abstract In terms of the responsive quality of cars, reducing the vibration of car seats is very important, as this vibration is transmitted directly to the driver. Here, a sensitivity analysis method was used to reasonably reduce the vibration of car seats at minimal cost. A laboratory test was conducted under two excitation conditions: first, vibration in idle state; second, random vibration not exceeding 100 Hz. To determine the reliability of the laboratory test, the actual vibration in idle state was simulated in a multi-axial simulation table for the idle excitation environment of cars that are sensitive to even the smallest changes in the environment. The frequencies of interest were selected by adding the sums of frequency response functions measured at the 24 nodal points of interest under the two excitation conditions. Sensitivity factors were derived at the 24 nodal points of interest and a design modification plan with relatively large sensitivity factors was suggested to reinforce the overall rigidity of the part modules containing the points of interest.
2014-04-01
Technical Paper
2014-01-0044
Tomoya Ishii, Tomohiro Sudo, Masanori Morikawa, Daisuke Nagahata
Abstract General analysis methods which are known as Transfer Path Analysis and Air borne Source Quantification have been extended to estimate forces of an air conditioner's parts and also clarify the path from air conditioner system. These results show noise transfer path to be improved. Originally, the existing methods are known to require considerable amount of time for the cause of complicated measurement to get analysis results. In the work of this paper, required measurement is simplified, and time reduction of 50% is achieved without critical decrease in analysis accuracy.
2014-04-01
Technical Paper
2014-01-0634
Carrie Kowsky, Edward Wolfe, Sourav Chowdhury, Debashis Ghosh, Mingyu Wang
Abstract With more vehicles adopting fuel-saving engine start-stop routines and with the number of hybrid and electric vehicles on the rise, automotive A/C (air conditioning) systems are facing a challenge to maintain passenger comfort during the time when the compressor is inactive due to engine shut down. Using PCM (Phase Change Material) in the evaporator enables it to store cold when the compressor is active and release it to the cooling air stream when the compressor is not running. A unique feature of Delphi's design is that a refrigerant thermosiphon mechanism inside the evaporator drives the energy transport between the PCM and air stream. Delphi's PCM evaporator extends comfort for short duration idle stops, reduces emissions, and increases fuel economy and electric drive range. In this paper, the design aspects of a thermosiphon based PCM cold storage evaporator are described and the performance and operation of the PCM evaporator in a MAC (Mobile Air Conditioning) system discussed.
2014-04-01
Technical Paper
2014-01-0632
Mickael Cormerais, Thierry Marimbordes, Stephane Warnery, David Chalet, Haitham Mezher, Laurent Roussel
Abstract The future environmental constraints [e.g. WLTC +RDE, CAFE, Euro 6.2, 7] for the pollutant emissions lead to new challenges for the internal combustion engine. One of the solutions to decrease the fuel consumption, the CO2 and pollutant emissions whilst keeping the same driving and thermal comforts is the engine's thermal management, in particular during the warm-up phase. Furthermore, the traditional cooling system is not designed to work at the new engine transient thermal conditions at a non-optimal temperature in terms of fuel economy and exhaust emission. This paper describes a new technology for engine cooling systems that is able to control the coolant flow and temperature in relation to the engine conditions such as load and rotational speed. With a no flow in crankcase cooling strategy and a high engine temperature regulation, the Active Cooling Thermomanagement Valve succeeds in decreasing the fuel consumption without deteriorating engine's performance. To validate this concept, endurance tests were performed to verify the wear and durability.
2014-04-01
Technical Paper
2014-01-0627
Felix Regin A, Abhinav Agarwal, Niraj Kumar Mishra
Abstract Increased engine thermal load, front end styling and compact vehicle requirements have led to significant challenges for vehicle front end designer to provide innovative thermal management solutions. The front end cooling module design which consists of condenser, radiator, fan and intercooler is an important part of design as it ensures adequate heat removal capacity of radiator over a wide range of operating conditions to prevent overheating of engine. The present study describes the optimization of cooling air flow opening in the front end using CFD methodology of a typical passenger car. The predicted vehicle system resistance curve and coolant inlet temperature to the radiator are used for the selection of cooling modules and to further optimize the front end cooling opening area. This leds to the successful optimization of the front end, selection of cooling modules with significant cost savings by reducing prototype testing and design cycle time.
2014-04-01
Technical Paper
2014-01-0586
Essam F. Abo-Serie, Mohamed Sherif, Dario Pompei, Adrian Gaylard
Abstract A potentially important, but inadequately studied, source of passengers' exposure to pollutants when a road vehicle is stationary, with an idling engine, results from the ingestion of a vehicle's own exhaust into the passenger compartment through the HVAC intake. We developed and applied a method to determine the fraction of a vehicle's exhaust entering the cabin by this route. Further the influence of three parameters: ambient tail-wind speed, vehicle ground clearance and tail pipe angle, is assessed. The study applies Computational Fluid Dynamic (CFD) simulation to the distribution of exhaust gasses around a vehicle motorized with a 2.2 liter Diesel engine. The simulation employs efficient meshing techniques and realistic loading conditions to develop a general knowledge of the distribution of the gasses in order to inform engineering design. The results show that increasing tail-wind velocity, tail-pipe angle and ground clearance reduces the presence of CO and NO at the HVAC intake.
2014-04-01
Technical Paper
2014-01-1184
Betty Belhassein, David Chalet, Pascal Chesse, Guillaume Alix, Romain Lebas
Abstract Emission regulations have become increasingly stringent in recent years. Current regulations need the development of a new worldwide driving cycle which gives greater weight to the pollutants emitted during transient phases or cold starts. Powertrains contain a large number of components such as multistage turbocharger systems; exhaust gas recirculation, after-treatment devices and sometimes an electric motor. In this context, 0D predictive models of heat transfer in the exhaust line, calibrated with experimental data, are particularly interesting. Many investigations are related to the development of precise control laws in order to optimize the light-off of after-treatment elements during the engine starting phase. A better understanding of the thermal phenomena occurring in the exhaust line is necessary. To study the heat transfer in the exhaust line of a Diesel engine during transient conditions, the temperature in the exhaust line must be known precisely. The experimental methodology followed by the authors contains three steps: first, temperature and pressure drops are made on a pulse generator to characterize properly each thermocouple (four different diameters).
2014-04-01
Technical Paper
2014-01-1183
Chao Ding, Zhibao Xu, Yunqing Zhang, Qiming Tao
Abstract Vehicle Thermal Management System (VTMS) is a cross-cutting technology that directly or indirectly affects engine performance, fuel economy, safety and reliability, driver/passenger comfort, emissions. This paper presents a novel methodology to investigate VTMS based on Modelica language. A detailed VTMS platform including engine cooling system, lubrication system, powertrain system, intake and exhaust system, HVAC system is built, which can predict the steady and transient operating conditions. Comparisons made between the measured and calculated results show good correlation and approve the forecast capability for VTMS. Through the platform a sensitivity analysis is presented for basic design variables and provides the foundation for the design and matching of VTMS. Modelica simulation language, which can be efficiently used to investigate multi-domain problems, was used to model and simulate VTMS.
2014-04-01
Technical Paper
2014-01-1181
Md Abdul Quaiyum, Mohammed Ismail, Amir Fartaj
Abstract Channel diameter is one of the most important parameters of a heat exchanger especially for a highly viscous fluid-flow. Narrow channel heat exchangers are believed to have better energy efficiency due to elevated heat transfer characteristics. Heat transfer and Fluid-flow behaviors of Automatic Transmission Fluid (ATF) have been experimentally investigated in a closed loop integrated thermal wind tunnel test facility using wavy finned Minichannel Heat Exchanger (MICHX). The experiment was conducted by varying the ATF Reynolds number from 3 to 30. The flow friction factors in minichannel were evaluated. For a fully developed laminar flow the friction factors were evaluated considering fluid viscosity effects due to temperature variation. The flow correlated with a Poiseuille equation while friction factors were analyzed considering constant property ratio. However, it showed different correlation when considered variable property ratio. A numerical analysis on friction factor for single serpentine MICHX did not follow the Poiseulle law for both cases of constant property ratio and variable property ratio.
2014-04-01
Technical Paper
2014-01-1198
Noboru Uchida, Akira Fukunaga, Hideaki Osada, Kazuaki Shimada
Abstract Heat loss reduction could be one of the most promising methods of thermal efficiency improvement for modern diesel engines. However, it is difficult to fully transform the available energy derived from a reduction of in-cylinder heat loss into shaft work, but it is rather more readily converted into higher exhaust heat loss. It may therefore be favorable to increase the effective expansion ratio of the engine, thereby maximizing the brake work, by transforming more of the enthalpy otherwise remaining at exhaust valve opening (EVO) into work. In general, the geometric compression ratio of a piston cylinder arrangement has to increase in order to achieve a higher expansion ratio, which is equal to a higher thermodynamic compression ratio. It is still necessary to overcome constraints on peak cylinder pressure, and other drawbacks, before applying higher expansion ratios to current high-boost, high brake mean effective pressure (BMEP), and high exhaust gas recirculation (EGR) diesel engines.
2014-04-01
Technical Paper
2014-01-1268
Dimitrios Angelos Mitakos, Christopher Blomberg, Yuri M. Wright, Peter Obrecht, Bruno Schneider, Konstantinos Boulouchos
Abstract The heat release of the low temperature reactions (LTR or cool-flame) under Homogeneous Charge Compression Ignition (HCCI) combustion has been quantified for five candidate fuels in an optically accessible Rapid Compression Expansion Machine (RCEM). Two technical fuels (Naphthas) and three primary reference fuels (PRF), (n-heptane, PRF25 and PRF50) were examined. The Cetane Numbers (CN) of the fuels range from 35 to 56. Variation of the operating parameters has been performed, in regard to initial charge temperature of 383, 408, and 433K, exhaust gas recirculation (EGR) rate of 0%, 25%, and 50%, and equivalence ratio of 0.29, 0.38, 0.4, 0.53, 0.57, and 0.8. Pressure indication measurements, OH-chemiluminescence imaging, and passive spectroscopy were simultaneously implemented. In our previous work, an empirical, three-stage, Arrhenius-type ignition delay model, parameterized on shock tube data, was found to be applicable also in a transient, engine-relevant environment. The pressure rise due to cool-flame heat release, which is crucial for the induction of main ignition, was included in the experimental pressure traces that have been used.
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