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Viewing 181 to 210 of 9793
Technical Paper
2014-04-01
Alaa El-Sharkawy, Asif Salahuddin, Brian Komarisky
In this paper a design methodology for automotive heat exchangers has been applied which brings robustness into the design process and helps to optimize the design goals: as to maintain an optimal coolant temperature and to limit the vehicle underhood air temperature within a tolerable limit. The most influential design factors for the heat exchangers which affect the goals have been identified with that process. The paper summarizes the optimization steps necessary to meet the optimal functional goals for the vehicle as mentioned above. Taguchi's [1] Design for Six Sigma (DFSS) methods have been employed to conduct this analysis in a robust way.
Technical Paper
2014-04-01
Tau Tyan, Jeff Vinton, Eric Beckhold, Xiangtong Zhang, Jeffrey Rupp, Nand Kochhar, Saeed Barbat
The objective of this paper focused on the modeling of an adaptive energy absorbing steering column which is the first phase of a study to develop a modeling methodology for an advanced steering wheel and column assembly. Early steering column designs often consisted of a simple long steel rod connecting the steering wheel to the steering gear box. In frontal collisions, a single-piece design steering column would often be displaced toward the driver as a result of front-end crush. Over time, engineers recognized the need to reduce the chance that a steering column would be displaced toward the driver in a frontal crash. As a result, collapsible, detachable, and other energy absorbing steering columns emerged as safer steering column designs. The safety-enhanced construction of the steering columns, whether collapsible, detachable, or other types, absorb rather than transfer frontal impact energy. Recently, more advanced steering column designs with adaptive features, mechanically or pyrotechnically activated, have been introduced for different crash conditions, including different crash severity, occupant mass/size, seat position and seatbelt usage.
Technical Paper
2014-04-01
Dinesh Pahuja, Arpit Kapila, Sanjay Haldar, Sandeep Raina
Interiors of past vehicles were created to satisfy specific functions with appearance being a secondary consideration, but in the present & future market with ever increasing vehicle luxury, decoration of vehicle has become a prime focus in automobile industry along with the safety & economy. Automotive interiors have evolved over the years from a collection of trims covering bare sheet metal panels to add quality & richness of interior cabin, ultimately delivering greater value to customers. One such area in interiors is Side door trims serving the dual purpose of functionality and creating a pleasing environment too. The aesthetic appeal to the Side door trim is added usually through a Door trim insert having a decorative skin pasted on to the plastic base. And the selection of pasting technique for pasting decorative film on to the plastic base insert is a challenge for an automotive interior designer. The objective of this paper will be to review technologies available for manufacturing Door trim inserts with decorative skins, and discuss a direction toward selecting an appropriate pasting technique with cost effectiveness.
Technical Paper
2014-04-01
Michael Kolich, Daniel Dooge, Mark Doroudian, Efim Litovsky, Richard Ng, Jacob Kleiman
Thermophysical properties of materials used in the design of automotive interiors are needed for computer simulation of climate conditions inside the vehicle. These properties are required for assessment of the vehicle occupants' thermal sensation as they come in contact with the vehicle interior components, such as steering wheels, arm rests, instruments panel and seats. This paper presents the results of an investigation into the thermophysical properties of materials which are required for solving the non-linear Fourier equations with any boundary conditions and taking into account materials' specific heat, volume density, thermal conductivity, and thermal optical properties (spectral and total emissivity and absorptivity). The model and results of the computer simulation will be published in a separate paper. The tested materials included foam, leather/foam laminated materials, and a few plastic laminated materials, which were used in the construction of various automotive interior parts.
Technical Paper
2014-04-01
Seishiro Murata, Hiroyuki Ito, Steven Sopher
Flexible polyurethane (PU) foam has been widely used for seat cushions in automotive passenger vehicles due to the excellent cushioning performance and the ability to shape mold. Originally introduced in the late 1950's, it has been used for more than 50 years. However, there is a limitation using polyurethane foam with efforts to reduce the weight and address ever increasing risks to environment. This paper provides information about a new automotive seat concept which does not use polyurethane foam at all. Expanded polyolefin foam is used for this application to replace polyurethane foam and achieve comparable cushioning performance. Other features of the material include 100% recyclability, and no VOC's. By replacing polyurethane foam with expanded thermoplastic foam, hazardous outgassing is eliminated during the seat cushion production, thus improving workplace environmental health and safety.
Technical Paper
2014-04-01
Rajiv Mehta, Mark Hadley
With the ever increasing pressure to improve the fuel economy of vehicles, there has been a corresponding interest in reducing the mass and size of vehicles. While mass is easily quantifiable, vehicle size, particularly the notion of “interior space” as perceived by the customer, is not. This paper explores different ways in which vehicle spaciousness can be quantified and explores new metrics based on customer verbatims. A novel ‘spaciousness calculator’ combines individual metrics to provide a singular holistic rating for spaciousness, useful during vehicle development. Beyond spaciousness, the paper discusses techniques to quantify the ‘packaging efficiency’ of a vehicle; this allows engineers to maximize the interior space for a given exterior size.
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
Mark Scibilia, Tim Giberson
As fuel prices continue to rise automotive manufacturers continue to push their suppliers to provide technology that improves the potential fuel efficiency of their applications. In addition there is an increasing trend towards smaller, lighter and more compact vehicles to mitigate the automotive carbon footprint. These movements necessitated the development of a new compact, low mass, variable displacement compressor to match the requirements for these smaller and more efficient vehicles. The new Delphi MVC, or Miniature Variable Compressor, meets these requirements by integrating the high efficiency of our latest swashplate variable compressor design into a compact and lightweight package. This design can be offered in a range of displacements from 80 to 100cc and can be offered as either internally or externally controlled to support the customer's needs.
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
Tibor Kiss, Jason Lustbader
The operation of air conditioning (A/C) systems is a significant contributor to the total amount of fuel used by light-and heavy-duty vehicles. Therefore, continued improvement of the efficiency of these mobile A/C systems is important. Numerical simulation has been used to reduce the system development time and to improve the electronic controls, but numerical models that include highly detailed physics run slower than desired for carrying out vehicle-focused drive cycle-based system optimization. Therefore, faster models are needed even if some accuracy is sacrificed. In this study, a validated model with highly detailed physics, the “Fully-Detailed” model, and two models with different levels of simplification, the “Quasi-Transient” and the “Mapped-Component” models, are compared. The Quasi-Transient model applies some simplifications compared to the Fully-Detailed model to allow faster model execution speeds. The Mapped-Component model is similar to the Quasi-Transient model except instead of detailed flow and heat transfer calculations in the heat exchangers, it uses lookup tables created with the Quasi-Transient model.
Technical Paper
2014-04-01
Mingyu Wang, Edward Wolfe, Debashis Ghosh, Jeffrey Bozeman, Kuo-huey Chen, Taeyoung Han, Hui Zhang, Edward Arens
Traditional vehicle air conditioning systems condition the entire cabin to a comfortable range of temperature and humidity regardless of the number of passengers in the vehicle. The A/C system is designed to have enough capacity to provide comfort for transient periods when cooling down a soaked car. Similarly for heating, the entire cabin is typically warmed up to achieve comfort. Localized heating and cooling, on the other hand, focuses on keeping the passenger comfortable by forming a micro climate around the passenger. This is more energy efficient since the system only needs to cool the person instead of the entire cabin space and cabin thermal mass. It also provides accelerated comfort for the passenger during the cooling down periods of soaked cars. Additionally, the system adapts to the number of passengers in the car, so as to not purposely condition areas that are not occupied. The present paper reports on a fundamental study of localized cooling to achieve comfort in a vehicle environment.
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
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
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
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
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.
Technical Paper
2014-04-01
Ludwig Brabetz, Mohamed Ayeb
For the prevention of technical risks and the optimum design of an electrical distribution system, considerable efforts have been made to implement thermal models of wires, bundles, and electromechanical components in order to improve thermal analysis. Unfortunately, in most cases, important input parameters such as the position of a wire within a bundle or the profiles of the currents are unknown. This leads to the use of worst-case scenarios, frequently providing unrealistic results and uneconomic over-dimensioning. The proposed approach is based on the thermal simulation of a large number of randomly-generated bundle configurations for given profiles of currents. Thus one gets a temperature distribution, allowing a much more precise analysis compared to a simple worst-case calculation. By applying the same method to various current profiles, one gets temperature distributions for each wire as a function of a normalized total bundle current. The finding is that statistics allow a very good thermal assessment despite unknown bundle configurations and current profiles.
Technical Paper
2014-04-01
Scott Peck, Aditya Velivelli, Wilko Jansen
Integration of advanced battery systems into the next generation of hybrid and electric vehicles will require significant design, analysis, and test efforts. One major design issue is the thermal management of the battery pack. Analysis tools are being developed that can assist in the development of battery pack thermal design and system integration. However, the breadth of thermal design issues that must be addressed requires that there are a variety of analysis tools to address them efficiently and effectively. A set of battery modeling tools has been implemented in the thermal modeling software code PowerTHERM. These tools are coupled thermal-electric models of battery behavior during current charge and discharge. In this paper we describe the three models in terms of the physics they capture, and their input data requirements. We discuss where the capabilities and limitations of each model best align with the different issues needed to be addressed by analysis. Model outputs are compared with measured data for various analysis scenarios, including simulation of constant current charge/discharge, and response to charge/discharge profiles derived from a standard drive cycle, for both single cell and multi-cell pack configurations.
Technical Paper
2014-04-01
Lijun Zhang, Hongzheng Cheng, Kun Diao, Cheng Ruan
To accurately and efficiently predict the temperature fields inside a lithium-ion battery is key technology for the enhancement of battery thermal management and the improvement of battery performances. The dimensional analysis method is applied to derive similarity criterions and the similarity coefficients of battery interior temperature fields, based on the governing partial differential equations describing the three dimensional transient temperature field. To verify the correctness of similarity criterions and the similarity coefficients, 3D finite element models of battery temperature field are established with a prototype and scale model, on the assumption that the battery cell has single-layer structure and multi-layers structure separately. The simulation results show that the similarity criterions and the similarity coefficients are correct. The calculation efficiency is checked to be much more efficient compared with FEM model based on the original cell structure in aspect of amount of resources occupied.
Technical Paper
2014-04-01
Jason Lisseman, Lisa Diwischek, Stefanie Essers, David Andrews
The last years have seen an increasing amount of innovations in the functionality of car electronics (e.g. advanced driver assistant systems (ADAS) and in-vehicle infotainment systems (IVIS)). These electrical systems are not reserved for premium cars anymore, but additionally reach mid-size, compact, and subcompact cars. The growing number of functionalities in these cars entails increasing amount of interfaces, which may confuse, overload, or annoy the driver. Accompanying this, there is a trend towards the integration of capacitive touchscreens as user interfaces. These touchscreens were implemented first in consumer electronics and had a substantial impact on the way in which users interact with technology. This in turn has led to an increased user driven demand for the technology to be implemented in other domains, even in safety-critical ones like the automotive area. Capacitive touchscreens have certain drawbacks in their distraction potential and their usability, leading to safety-critical situations and negative user feedback.
Technical Paper
2014-04-01
Yinhua Zheng
Abstract This paper addresses various ways to determine vehicle dual AC system charge level. Traditionally, either checking charge level plateau and/or using the certain condenser outlet subcooling magnitude are adopted to determine AC system charge level. It is challenging to determine refrigerant charge level in the following scenarios: (1) Some AC systems do not exhibit the flatted charge plateau. (2) The condenser outlet subcooling continues to rise. (3) The system has the requirements to run both front and aux evaporators, front evaporator only and aux evaporator only. It was found that compressor compression ratio of absolute discharge pressure to absolute suction pressure always presents the bath tub curve for all AC systems. When the system reaches the optimal charge level, the evaporator air outlet temperatures show the stable trend. In addition to the traditional condenser subcooling method, few approaches are presented in the paper. One way to determine the dual evaporator system charge level is: checking compressor compression ratios vs. charge level on the tests with (1) running both front and aux evaporators, (2) running front evaporator only (aux evaporator off).
Technical Paper
2014-04-01
Mirko Schulze, Rashad Mustafa, Benjamin Tilch, Peter Eilts, Ferit Küçükay
Hybrid electric vehicles (HEVs) are facing increased challenges of optimizing the energy flow through a vehicle system, to enhance both the fuel economy and emissions. Energy management of HEVs is a difficult task due to complexity of total system, considering the electrical, mechanical and thermal behavior. Innovative thermal management is one of the solutions for reaching these targets. In this paper, the potential of thermal management for a parallel HEV with a baseline control strategy under different driving cycles and ambient temperatures is presented. The focus of the investigations is on reducing fuel consumption and increasing comfort for passengers. In the first part of this paper, the developed HEV-model including the validation with measurements is presented. In the second part, the combined thermal management measures, for example the recuperation of exhaust-gas energy, engine compartment encapsulation and the effect on the target functions are discussed. Simulation results show potential of reduction fuel consumption together with increasing the comfort for the passenger cabin.
Technical Paper
2014-04-01
Vijay Somandepalli, Kevin Marr, Quinn Horn
As lithium-ion cells and systems become larger and more ubiquitous in automotive applications, fire and explosion hazards that are rare or non-existent in smaller systems may exist in these larger systems. One potential hazard can occur when flammable gases emitted from a lithium-ion cell failure accumulate in or around automobiles and are ignited by electrical activity or by the cells themselves and result in a fire or explosion. In some instances, the safety aspects related to fires and explosions protection of electric vehicles and hybrid vehicles using these large energy storage battery packs are a significant challenge to address. This paper describes and characterizes the combustion and explosion hazards that can occur when a lithium ion battery pack fails and goes into thermal runaway in an enclosed space. Metrics such as gas composition, maximum overpressure, rate of pressure rise, and flammability limits are described. This information can be helpful to battery and pack designers, vehicle designers, first responders and emergency personnel in developing strategies to mitigate and prevent explosion hazards from the use of battery packs in automobiles and other fields where large battery packs are used.
Technical Paper
2014-04-01
Xueyu Zhang, Andrej Ivanco, Xinran Tao, John Wagner, Zoran Filipi
This paper investigates the impact of battery cooling ancillary losses on fuel economy, and optimal control strategy for a series hybrid electric truck with consideration of cooling losses. Battery thermal model and its refrigeration-based cooling system are integrated into vehicle model, and the parasitic power consumption from cooling auxiliaries is considered in power management problem. Two supervisory control strategies are compared. First, a rule-based control strategy is coupled with a thermal management strategy; it controls power system and cooling system separately. The second is optimal control strategy developed using Dynamic Programming; it optimizes power flow with consideration of both propulsion and cooling requirement. The result shows that battery cooling consumption could cause fuel economy loss as high as 5%. When dynamic programming coordinates control of the powertrain and the cooling system in an optimal way, the fuel consumption penalty due to cooling losses is reduced to 3.7%, and battery duty cycle becomes milder.
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.
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