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Technical Paper
2014-04-01
Steve De Vos, Kristian Haehndel, Torsten Frank, Frieder Christel, Sylvester Abanteriba
Modern exhaust systems contain not only a piping network to transport hot gas from the engine to the atmosphere, but also functional components such as the catalytic converter and turbocharger. The turbocharger is common place in the automotive industry due to their capability to increase the specific power output of reciprocating engines. As the exhaust system is a main heat source for the under body of the vehicle and the turbocharger is located within the engine bay, it is imperative that accurate surface temperatures are achieved. A study by K. Haehndel [1] implemented a 1D fluid stream as a replacement to solving 3D fluid dynamics of the internal exhaust flow. To incorporate the 3D effects of internal fluid flow, augmented Nusselt correlations were used to produce heat transfer coefficients. It was found that the developed correlations for the exhaust system did not adequately represent the heat transfer of the turbocharger. This paper addresses the fluid flow phenomena present in the turbine volute and applies augmented Nusselt correlations to accurately represent the heat transfer coefficients of the internal volute surface.
Technical Paper
2014-04-01
Yousof Azizi, Vaidyanadan Sundaram, Patricia Davies, Anil Bajaj
Flexible polyurethane foam is the main cushioning element used in car seats. Optimization of an occupied seat's static and dynamic behavior requires models of foam that are accurate over a wide range of excitation and pre-compression conditions. In this research, a method is described to estimate the parameters of a global model of the foam behavior from data gathered in a series of impulse tests at different settling points. The estimated model is capable of describing the responses gathered from all the impulse tests using a unique set of parameters. The global model structure includes a nonlinear elastic term and a hereditary viscoelastic term. The model can be used to predict the settling point for each mass used and, by expanding the model about that settling point, local linear models of the response to impulsive excitation can be derived. From this analysis the relationship between the local linear model parameters and the global model parameters is defined. A series of experiments are conducted using different sized masses on the foam block.
Technical Paper
2014-04-01
Rupesh Sonu Kakade
We propose a composite thermal model of the vehicle passenger compartment that can be used to predict and analyze thermal comfort of the occupants of a vehicle. Physical model is developed using heat flow in and out of the passenger compartment space, comprised of glasses, roof, seats, dashboard, etc. Use of a model under a wide variety of test conditions have shown high sensitivity of compartment air temperature to changes in the outside air temperature, solar heat load, temperature and mass flow of duct outlet air from the climate control system of a vehicle. Use of this model has subsequently reduced empiricism and extensive experimental tests for design and tuning of the automatic climate control system. Simulation of the model allowed several changes to the designs well before the prototype hardware is available. In addition to the reduced vehicle field tests and wind tunnel tests man hours and the cost associated with them, simulation of the model allowed for the greater potential benefits of increased accuracy and optimized heating and cooling of the passenger compartment to be achieved.
Technical Paper
2014-04-01
Alaa El-Sharkawy, Ahmed Uddin
In this paper, thermal models are developed based on experimental test data, and the physics of thermal systems. If experimental data is available, the data can be fitted to mathematical models that represent the system response to changes in its input parameters. Therefore, empirical models which are based on test data are developed. The concept of time constant is presented and applied to development of transient models. Mathematical models for component temperature changes during transient vehicle driving conditions are also presented. Mathematical models for climate control system warm up and cool-down are also discussed. The results show the significance of adopting this concept in analysis of vehicle test data, and in development of analytical models. The developed models can be applied to simulate the system or component response to variety of changes in input parameters. As a result, significant testing and simulation time can be saved during the vehicle development process.
Technical Paper
2014-04-01
Shenghan Jin, Predrag Hrnjak
The paper presents a semi-empirical model to predict refrigerant and lubricant inventory in both evaporator and condenser of an automotive air conditioning (MAC) system. In the model, heat exchanger is discretized into small volumes. Temperature, pressure and mass inventory are calculated by applying heat transfer, pressure drop and void fraction correlations to these volumes respectively. Refrigerant and lubricant are treated as a zeotropic mixture with a temperature glide. As refrigerant evaporates or condenses, thermophysical properties are evaluated accordingly with the change of lubricant concentration. Experimental data is used to validate the model. As a result, refrigerant and lubricant mass is predicted within 20% in the evaporator. However, in the condenser, lubricant mass was consistently under-predicted while refrigerant mass was predicted within 15% error. Moreover, the lubricant under-prediction becomes more significant at higher Oil Circulation Ratio (OCR). The analysis showed that the lubricant is separated from the flow in the condenser header and starts to accumulate in the bottom channels.
Technical Paper
2014-04-01
Mohammed K Billal, B V Moorthy, Dan Aquilina, Steven Schenten
Abstract A snap-fit is a form-fitting joint, which is used to assemble plastic parts together. Snap-fits are available in different forms like a projecting clip, thicker section or legs in one part, and it is assembled to another part through holes, undercuts or recesses. The main function of the snap-fit is to hold the mating components, and it should withstand the vibration and durability loads. Snap-fits are easy to assemble, and should not fail during the assembling process. Based on the design, these joints may be separable or non-separable. The non- separable joints will withstand the loads till failure, while separable joints will withstand only for the design load. The insertion and the retention force calculation for the snaps are very essential for snap-fit design. The finite element analysis plays a very important role in finding the insertion and the retention force values, and also to predict the failure of the snaps and the mating components during this process. The snap insertion and retention simulation is highly non-linear, due to the non-linear material behavior and contact between the mating components.
Technical Paper
2014-04-01
Tetsu Yamada, Shouji Adachi, Koichi Nakata, Takashi Kurauchi, Isao Takagi
From the time the first Hybrid Vehicle (HV) was launched, 17 years have past, and HV vehicles have boosted the global CO2 reduction trend. In order to maximize their merit, many HV engines focused on the best fuel consumption value namely thermal efficiency. This was because HV systems can control the operating area of engine and get merit. However, considering climate change and energy issues, it is important to focus conventional vehicle as well as HV vehicle progress. The Atkinson cycle with a high compression ratio is the typical approach that HV engines use to enhance thermal efficiency. However, the drawback of the high compression ratio is a reduction of engine torque. Thermal efficiency at low load areas is relatively more important with conventional engines than with HV engines and how to overcome these issues is significantly important with conventional engines. The engines which have technologies contributing to lower the vehicle fuel economy are described as ESTEC (Economy with Superior Thermal Efficient Combustion) engines.
Technical Paper
2014-04-01
Sebastian Salbrechter, Markus Krenn, Gerhard Pirker, Andreas Wimmer, Michael Nöst
Abstract Optimization of engine warm-up behavior has traditionally made use of experimental investigations. However, thermal engine models are a more cost-effective alternative and allow evaluation of the fuel saving potential of thermal management measures in different driving cycles. To simulate the thermal behavior of engines in general and engine warm-up in particular, knowledge of heat distribution throughout all engine components is essential. To this end, gas-side heat transfer inside the combustion chamber and in the exhaust port must be modeled as accurately as possible. Up to now, map-based models have been used to simulate heat transfer and fuel consumption; these two values are calculated as a function of engine speed and load. To extend the scope of these models, it is increasingly desirable to calculate gas-side heat transfer and fuel consumption as a function of engine operating parameters in order to evaluate different ECU databases. This paper describes the creation of a parameter-based heat transfer model using a statistical approach.
Technical Paper
2014-04-01
Brian Pinkelman
Abstract Experience tells us that one can develop a technically comfortable seat where the seat fits and supports the occupant. The pressure distribution is optimized and the seat and packaging are such that a good posture is attainable by many. The dynamic characteristics of the seat and the vehicle are technically good. Despite all this the customer is not satisfied. Despite it being a technically comfortable seat, it does meet the customers' expectations and/or priorities and thus the comfort provided is lacking. This paper seeks to explore that gap between the seat and the user by modeling comfort using techniques similar to those found in the social sciences where models often focus on user or individual behavior. The model is built upon but diverges from the Cobb Douglas consumer utility model found in economics. It is presented as theory and presents a very different perspective on comfort. The model should be used not as a replacement but a complement to the more traditional technical models of comfort that model the seat.
Technical Paper
2014-04-01
Se Jin Park, Seung Nam Min, Murali Subramaniyam, Dong-Hoon Lee, Heeran Lee, Dong Gyun Kim
Abstract Seating comfort is one of the most important indicators of the performance of automotive seats. The objective and subjective evaluation of seating comfort plays an important role in the development of seating systems. Objective methods are primarily based on evaluating the influence of vibrations on the driver's seat and assessing the seat pressure ratio. The primary goal of this study was to evaluate the comfort of two car seats (sedan and compact) by comparing a subjective technique with an objective technique like body pressure ratio for a sample of 12 subjects. The results show that the pressure ratio for IT (ischial tuberosity) and L4/L5 were significantly greater for the seat of a compact car than the seat of a sedan car. The subjective comfort was significantly greater for the seat of the sedan car and females than the seat of the compact car and males, respectively. The combination of valid objective measures with subjective ratings of comfort and discomfort may give information of use to seat designers.
Technical Paper
2014-04-01
Manuel Lorenz, Dusan Fiala, Markus Spinnler, Thomas Sattelmayer
Abstract Cabin heating and cooling loads of modern vehicles, notably electrically driven, represent a major portion of the overall vehicle energy consumption. Various concepts to reduce these loads have thus been proposed but quantitative experimental analysis or numerical predictions are scarcely available. Conventional 1D or zonal cabin models do not account adequately for strongly inhomogeneous cabin climate conditions. In this paper a new cabin model is presented, which delivers both temporally and spatially resolved data. The model uses a dynamic coupling algorithm including a CFD simulation of the cabin airflow, a model of the cabin structure and the detailed passenger Fiala Physiological Comfort (FPC) model. The coupling not only includes heat transport between the cabin air and the surrounding surfaces, but also considers important interactions with the occupants, including e.g. the release of moisture into the cabin air by respiration and sweating predicted by the Fiala Physiological Comfort model and the heat exchange between occupant body parts and solid surfaces by radiation and conduction.
Technical Paper
2014-04-01
Chuqi Su, Zhengzhong Chu
Driving comfort is one of the most important indexes for automobile comfort. Driving posture comfort is closely related to the drivers' joint angles and joint torques. In present research, a new method is proposed to identify the most comfortable driving posture based on studying the relation between drivers' joint angles and joint torques. In order to truly reflect a driving situation, the accurate human driving model of 50 percent of the size of Chinese male is established according to the human body database of RAMSIS firstly. Biomechanical model based on accurate human driving model is also developed to analyze and obtain dynamic equations of human driving model by employing Kane method. The joint torque-angle curves of drivers' upper and lower limbs during holding wheel or pedal operation can be obtained through dynamic simulation in the MATLAB. Through curve-fitting analysis, the minimum joint torque of a driver' limb and the optimal joint angel can be found. As an important reference, these parameters can be used to optimize driving seat structure and offer an important support for the optimization of cab package.
Technical Paper
2014-04-01
Simon Huber, Thomas Indinger, Nikolaus Adams, Thomas Schuetz
The optimization of the flow field around new vehicle concepts is driven by aerodynamic and thermal demands. Even though aerodynamics and thermodynamics interact, the corresponding design processes are still decoupled. Objective of this study is to include a thermal model into the aerodynamic design process. Thus, thermal concepts can be evaluated at a considerably earlier design stage of new vehicles, resulting in earlier market entry. In a first step, an incompressible CFD code is extended with a passive scalar transport equation for temperature. The next step also accounts for buoyancy effects. The simulated development of the thermal boundary layer is validated on a hot flat plate without pressure gradient. Subsequently, the solvers are validated for a heated block with ground clearance: The flow pattern in the wake and integral heat transfer coefficients are compared to wind tunnel simulations. The main section of this report covers the validation on a full-scale production car. A specially developed heated electronic component dummy mounted to the underbody of the car introduces heat into the flow field.
Technical Paper
2014-04-01
Ankang Jin, Weiguo Zhang, Shihu Wang, Yu Yang, Yunqing Zhang
The suspension system of a heavy truck's driver seat plays an important role to reduce the vibrations transmitted to the seat occupant from the cab floor. Air-spring is widely used in the seat suspension system, for the reason that its spring rate is variable and it can make the seat suspension system keep constant ‘tuned’ frequency compared to the conventional coil spring. In this paper, vibration differential equation of air-spring system with auxiliary volume is derived, according to the theory of thermodynamic, hydrodynamics. The deformation-load static characteristic curves of air-spring is obtained, by using a numerical solution method. Then, the ADAMS model of the heavy truck's driver seat suspension system is built up, based on the structure of the seat and parameters of the air-spring and the shock-absorber. At last, the model is validated by comparing the simulation results and the test results, considering the seat acceleration PSD and RMS value.
Technical Paper
2014-04-01
Vincent Laurent, Christophe Then, Gerhard Silber
Comfort is a main factor in customer's decision when buying a car. The seat plays a very important role, as it is the interface between occupant and vehicle. Pressure distribution is today's most common approach to characterize seat comfort, but it shows limitations. Analysis of human inter-tissue stress tends to be relevant for an objective comfort assessment. This paper presents the construction and validation of a CAE human model, based on Magnetic Resonance Imaging scans and in-vivo tests data. Correlation between objective criteria and subjective evaluation will be investigated, comfort performance of a real seat will be predicted.
Technical Paper
2014-04-01
Saeed Asgari, Xiao Hu, Michael Tsuk, Shailendra Kaushik
The thermal behavior of a fluid-cooled battery can be modeled using computational fluid dynamics (CFD). Depending on the size and complexity of the battery module and the available computing hardware, the simulation can take days or weeks to run. This work introduces a reduced-order model that combines proper orthogonal decomposition, capturing the variation of the temperature field in the spatial domain, and linear time-invariant system techniques exploiting the linear relationship between the resulting proper orthogonal decomposition coefficients and the uniform heat source considered here as the input to the system. After completing an initial CFD run to establish the reduction, the reduced-order model runs much faster than the CFD model. This work will focus on thermal modeling of a single prismatic battery cell with one adjacent cooling channel. The extension to the multiple input multiple output case such as a battery module will be discussed in another paper.
Technical Paper
2014-04-01
Akihito Hosoi, Atsushi Morita, Naoto Suzuki
At the engine restart, when the temperature of the catalytic converter is low, additional fuel consumption would be required to warm up the catalyst for controlling exhaust emission.The aim of this study is to find a thermally optimal way to reduce fuel consumption for the catalyst warm up at the engine restart, by improving the thermal retention of the catalytic converter in the cool down process after the previous trip. To make analysis of the thermal flow around the catalytic converter, a 2-D thermal flow model was constructed using the thermal network method. This model simulates the following processes: 1) heat conduction between the substrate and the stainless steel case, 2) heat convection between the stainless steel case and the ambient air, 3) heat convection between the substrate and the gas inside the substrate, 4) heat generation due to chemical reactions. The points to be especially noted are: a) in the cool down process, free convection of the gas inside the substrate was based on Darcy's law, b) in the engine operating condition, chemical phenomena and species mass balance in gas phase and catalyst surface was considered.
Technical Paper
2014-04-01
Francisco Payri, Pablo Olmeda, Jaime Martin, Ricardo Carreño
The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to specific submodels for all the relevant subsystems. Hence, the heat transfer from gases to engine walls is obtained with convective and radiative models in the chamber and ports; the repartition of the heat flux throughout the engine metal elements towards the oil and coolant is estimated with a lumped capacitance model; finally, the auxiliary systems and friction losses are obtained through specific semiempirical submodels.
Technical Paper
2014-04-01
Akira Kikusato, Katsuya Terahata, Kusaka Jin, Yasuhiro Daisho
Abstract The objective of this work is to develop a numerical simulation model of spark ignited (SI) engine combustion and thereby to investigate the possibility of reducing heat losses and improving thermal efficiency by applying a low thermal conductivity and specific heat material, so-called heat insulation coating, to the combustion chamber wall surface. A reduction in heat loss is very important for improving SI engine thermal efficiency. However, reducing heat losses tends to increase combustion chamber wall temperatures, resulting in the onset of knock in SI engines. Thus, the numerical model made it possible to investigate the interaction of the heat losses and knock occurrence and to optimize spark ignition timing to achieve higher efficiency. Part 2 of this work deals with the investigations on the effects of heat insulation coatings applied to the combustion chamber wall surfaces on heat losses, knock occurrence and thermal efficiency. To reduce engine heat losses and improve the thermal efficiency, the heat insulation coating was applied to the combustion chamber wall surfaces.
Technical Paper
2014-04-01
Akira Kikusato, Kusaka Jin, Yasuhiro Daisho
The first objective of this work is to develop a numerical simulation model of the spark ignited (SI) engine combustion, taking into account knock avoidance and heat transfer between in-cylinder gas and combustion chamber wall. Secondly, the model was utilized to investigate the potential of reducing heat losses by applying a heat insulation coating to the combustion chamber wall, thereby improving engine thermal efficiency. A reduction in heat losses is related to important operating factors of improving SI engine thermal efficiency. However, reducing heat losses tends to accompany increased combustion chamber wall temperatures, resulting in the onset of knock in SI engines. Thus, the numerical model was intended to make it possible to investigate the interaction of the heat losses and knock occurrence. The present paper consists of Part 1 and 2. Part 1 deals with the description of the numerical model and the fundamental characteristics of instantaneous temperature swings in the combustion chamber wall.
Technical Paper
2014-04-01
Peter Eilts, Claude-Pascal Stoeber-Schmidt
A model for the calculation of heat release in direct injection Diesel engines is presented. It needs only one engine-specific experimental parameter. In the form the model is presented here it is limited to the medium and upper load range, where Diesel combustion is mainly mixing controlled. The development of the model is based on data from medium speed engines. The applicability to automotive engines is shown in some examples. The model is based on the theory of single phase turbulent jets. Starting from the balance of momentum and fuel mass flow the stationary part of the jet can be calculated. The propagation of the front of the unsteady jet is determined from a continuity consideration. Heat release is calculated based on the assumptions of the Simple Chemically Reacting System (SCRS). Fuel that is mixed with air is assumed to be burnt instantaneously. Adjustment of the model to a good correspondence of measured and calculated heat release results in an experimental parameter which is in the same range as the figures published for turbulent jet flames.
Technical Paper
2014-04-01
Johann C. Wurzenberger, Tomaz Katrasnik
This works presents a real-time capable simulation model for dual fuel operated engines. The computational performance is reached by an optimized filling and emptying modeling approach applying tailored models for in-cylinder combustion and species transport in the gas path. The highly complex phenomena taking place during Diesel and gasoline type combustion are covered by explicit approaches supported by testbed data. The impact of the thermodynamic characteristics induced by the different fuels is described by an appropriate set of transport equations in combination with specifically prepared property databases. A thermodynamic highly accurate 6-species approach is presented. Additionally, a 3-species and a 1-species transport approach relying on the assumption of a lumped fuel are investigated regarding accuracy and computational performance. The comparison of measured and simulated pressure and temperature traces shows very good agreement. The real-time factor of a 6 cylinder medium speed engine is in the range of 0.2 for all species transport approaches, enabling the support of HiL based function development and calibration.
Technical Paper
2014-04-01
Arnon Poran, Moris Artoul, Moshe Sheintuch, Leonid Tartakovsky
This paper describes a model for the simulation of the joint operation of internal combustion engine (ICE) with methanol reformer when the ICE is fed by the methanol steam reforming (SRM) products and the energy of the exhaust gases is utilized to sustain endothermic SRM reactions. This approach enables ICE feeding by a gaseous fuel with very favorable properties, thus leading to increase in the overall energy efficiency of the vehicle and emissions reduction. Previous modeling attempts were focused either on the performance of ICE fueled with SRM products or on the reforming process simulation and reactor design. It is clear that the engine performance is affected by the composition of the reforming products and the reforming products are affected by the exhaust gas temperature, composition and flow rate. Due to the tight interrelations between the two main parts of the considered ICE-reformer system, it is desirable to create a single model that simulates joint operation of the ICE and the SRM reactor.
Technical Paper
2014-04-01
Owais Iqbal, Kunal Arora, Manyam Sanka
Accurate numerical prediction of an engine thermal map at a wide range of engine operating conditions can help tune engine performance parameters at an early development stage. This study documents the correlation of an engine thermal simulation using the conjugate heat transfer (CHT) methodology with thermocouple data from an engine operating in a dynamometer and a vehicle drive cell. Three different operating conditions are matched with the simulation data. Temperatures predicted by simulation at specific sections, both at the intake and the exhaust sides of the engine are compared with the measured temperatures in the same location on the operating engine.
Technical Paper
2014-04-01
Eric Gingrich, Jaal Ghandhi, Rolf D. Reitz
Abstract An experimental study has been conducted to provide insight into heat transfer to the piston of a light-duty single-cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition (HCCI), and Reactivity Controlled Compression Ignition (RCCI) combustion regimes. Two fast-response surface thermocouples embedded in the piston top measured transient temperature. A commercial wireless telemetry system was used to transmit thermocouple signals from the moving piston. A detailed comparison was made between the different combustion regimes at a range of engine speed and load conditions. The closed-cycle integrated and peak heat transfer rates were found to be lower for HCCI and RCCI when compared to CDC. Under HCCI operation, the peak heat transfer rate showed sensitivity to the 50% burn location.
Article
2014-03-31
Southco expands its tilt display mount (T Series) product line with the AV-D25 mount basic that provides proven tilt positioning and offers a solution for moving heavy panels and displays.
Article
2014-03-31
Maximatecc introduces the CCpilot VC product platform featuring an efficient ARM core, advanced software platform and readable 5-in (127-mm) display.
Article
2014-03-31
A comprehensive range of Isobus virtual terminal designs from American Industrial Systems are suitable for special applications on off-highway vehicles.
Standard
2014-03-31
This Information Report contains a definition of road vehicle hands-free operation. This definition applies to driver inputs to a wireless communications device used for person-to-person wireless communications while driving. This report applies to both original equipment manufacturers’ and aftermarket devices. The definition does not apply to outputs, e.g., visual or haptic feedback, from a communication system or device, regardless of the modality of human-machine interface. It also does not apply to parallel or redundant manual control operating modes.
Article
2014-03-27
TRW Automotive's second-generation active control retractor system (ACR2) has started production on the 2014 Cadillac CTS.
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