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2014-04-01
Journal Article
2014-01-0648
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.
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.
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.
2014-04-01
Technical Paper
2014-01-0677
Saiful Bari, Shekh Rubaiyat
Abstract The heat from the exhaust gas of diesel engines can be an important heat source to provide additional power using a separate Rankine Cycle (RC) or an Organic Rankine Cycle (ORC). Water is the best working fluid for this type of applications in terms of efficiency of the RC system, availability and environmental friendliness. However, for small engines and also at part load operations, the exhaust gas temperature is not sufficient enough to heat the steam to be in superheated zone, which after expansion in the turbine needs to be in superheated zone. Ammonia was found to be an alternate working fluid for these types of applications which can run at low exhaust temperatures. Computer simulation was carried out with an optimized heat exchanger to estimate additional power with water and ammonia as the working fluids. ANSYS 14.0 CFX software was used for the simulation.
2014-04-01
Technical Paper
2014-01-0678
Takatoshi Furukawa, Masaaki Nakamura, Koichi Machida, Kiyohiro Shimokawa
Abstract In heavy duty (HD) trucks cruising on expressway, about 60% of input fuel energy is wasted as losses. So it is important to recover them to improve fuel economy of them. As a waste heat recovery system, a Rankine cycle generating system was selected. And this paper mainly reports it. In this study, engine coolant was determined as main heat source, which collected energies of an engine cooling, an EGR gas and an exhaust gas, for collecting stable energy as much as possible. And the exergy of heat source was raised by increase coolant temperature to 105 deg C. As for improving the system efficiency, saturation temperature difference was expanded by improving performance of heat exchanger and by using high pressure turbine. And a recuperator which exchanges heat in working fluid between expander outlet and evaporator inlet was installed to recover the heat of working fluid at turbine generator. Then a working fluid pump was improved to reduce power consumption of the system.
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.
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.
2014-04-01
Technical Paper
2014-01-0672
Andrew P. Roberts, Richard Brooks, Philip Shipway, Robert Gilchrist, Ian Pegg
Abstract The thermal efficiency of an internal combustion engine at steady state temperatures is typically in the region of 25-35%[1]. In a cold start situation, this reduces to be between 10% and 20% [2]. A significant contributor to the reduced efficiency is poor performance by the engine lubricant. Sub optimal viscosity resulting from cold temperatures leads to poor lubrication and a subsequent increase in friction and fuel consumption. Typically, the engine lubricant takes approximately twenty minutes [3] to reach steady state temperatures. Therefore, if the lubricant can reach its steady state operating temperature sooner, the engine's thermal efficiency will be improved. It is hypothesised that, by decoupling the lubricant from the thermal mass of the surrounding engine architecture, it is possible to reduce the thermal energy loss from the lubricant to the surrounding metal structure in the initial stages of warm-up.
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.
2014-04-01
Journal Article
2014-01-0669
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.
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.
2014-04-01
Journal Article
2014-01-0665
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.
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.
2014-04-01
Technical Paper
2014-01-0664
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.
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.
2014-04-01
Technical Paper
2014-01-0645
Gianluca Montenegro, Augusto Della Torre, Angelo Onorati, Dalia Broggi, Gerd Schlager, Christian Benatzky
Abstract This work proposes a focus on the simulation of a rotative volumetric expander via a CFD code. A customized application of OpenFOAM® has been developed to handle the particular motion of the calculation grid. The model uses a mesh to mesh interpolation technique, switching from a calculation grid to the new one on the basis of mesh quality considerations performed on the fly. This particular approach allows to account for the presence of leakages occurring between the stator and blade tips and also occurring at the top and bottom of the vanes. The fluid considered is the refrigerant R245fa, whose particular properties have been determined resorting to the NIST database. Experimental data, measured at different conditions of mass flow and fluid temperature, are compared to calculation results. Moreover, the CFD analysis has allowed the estimation of the influence of the leakage mass flow occurring at the tip of the vanes on the overall machine performances.
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.
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.
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
Journal Article
2014-01-0630
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.
2014-04-01
Technical Paper
2014-01-0688
Kambiz Jahani, Sajjad Beigmoradi
Abstract Adequate visibility through the automobile windscreen is a critical aspect of driving, most often at very low temperatures when ice tends to be formed on the windscreen. The geometry of the existing defroster system needs to be improved in the vehicles, with the main aim of substantial increase in air mass flow reaching the windscreen through defroster nozzles and appropriate velocity distribution over the windscreen, while respecting all packaging constraints. The reason of this study is to investigate the windscreen deicing behavior of a vehicle by means of Computational Fluid Dynamics (CFD) with the main concern of improving deicing process by design an appropriate defroster. Two different defrosters with completely different geometry are considered for this purpose. A detailed full interior model of an existing vehicle is created via CAE tools.
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.
2014-04-01
Technical Paper
2014-01-0682
Pengyi Cui, Bin Xu
Abstract Air purifier has been prevalently used in the passenger vehicle cabins to reduce in-cabin UltraFine Particle (UFP) concentration. In this study, Computational Fluid Dynamics (CFD) was applied to simulate the in-cabin UFP transport and distribution under different ventilation modes with different characteristics of the air purifier. Ventilation settings, air purifier settings, and air purifier location were identified as the important factors determining the in-cabin UFP distribution and transport. Downward ventilation airflow direction and smaller ventilation air velocity can be considered by the drivers for a lower in-cabin UFP concentration. Upward airflow direction from the air purifier's inlet and larger air velocity were recommended since it led up to 50% in-cabin UFP reduction. Air purifier installed at middle ceiling of the cabin develops the most efficient airflow for UFP removal.
2014-04-01
Technical Paper
2014-01-0685
Devin Furse, SeKil Park, Lee Foster, Simon Kim
Abstract An innovative system has been developed to remotely monitor and record customer usage patterns of the Hyundai Genesis HVAC system in real time by smartphone. The data monitored includes dozens of HVAC-related parameters, including driver and passenger set temperature, blower setting, mode and intake position, internal software parameters, etc. This information and understanding of real-world usage of American customers enables design and test engineers to better satisfy customer demands for automatic temperature control performance. This study identifies areas in need of improvement Preliminary findings of this study suggest that auto mode usage is highest in mild temperatures and lowest in hot soaking conditions. In hot soak conditions (above 35C cabin temperature), the majority of American customers manually control the temperature and blower speed.
2014-04-01
Technical Paper
2014-01-0681
Shivakumar Banakar, Dirk Limperich, Ramesh Asapu, Vaishnavi Panneerselvam, Madhu Singh
Abstract Air-cooled fin and tube heat exchangers are used as a condenser in the conventional automotive Heating Ventilation & Air-Conditioning (HVAC) systems. In this study, the use of liquid cooled plate heat exchanger as a condenser in the automotive HVAC systems has been investigated. In the proposed configuration, the cabin heat absorbed by the refrigerant in HVAC system is rejected to the coolant through a liquid cooled condenser and then to the ambient air through a low temperature radiator. Hence, the proposed configuration combines heat rejection from HVAC system with a low temperature radiator circuit of power train cooling. Mixture of Ethylene glycol & Water (coolant), which is used in power train cooling system, is used as secondary fluid in the condenser.
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+.
2014-04-01
Journal Article
2014-01-0687
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.
2014-04-01
Journal Article
2014-01-0686
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.
2014-04-01
Technical Paper
2014-01-0443
Michael Tschirhart, Kathleen Ku
Abstract The vehicle environment is known to be a demanding context for efficiently displaying information to the driver. Research in typography reveals some factors that influence reading performance measures, but there is limited research on the influence of typographic design elements in a driver-vehicle interface on user performance with a simulated driver task. Participants in these studies completed a set of vehicle infotainment tasks that involved a text-based item search in a custom-designed interface that employed a family of Helvetica Neue fonts, in a static environment and a driving simulator environment. Analysis of the data from the two studies reveals a modest but statistically significant effect of font on certain driving-related task performance measures. In both studies, fonts with intermediate values of character width and line thickness were associated with the best performance on a simulated driving task.
2014-04-01
Technical Paper
2014-01-0455
Alessandro Naddeo, Nicola Cappetti, Orlando Ippolito
Abstract General comfort may be defined as the “level of well-being” perceived by humans in a working environment. The state-of-the-art about evaluation of comfort/discomfort shows the need for an objective method to evaluate the “effect in the internal body” and “perceived effects” in main systems of comfort perception. In the early phases of automotive design, the seating and dashboard command can be virtually prototyped, and, using Digital Human Modeling (DHM) software, several kinds of interactions can me modeled to evaluate the ergonomics and comfort of designed solutions. Several studies demonstrated that DHM approaches are favorable in virtual reachability and usability tests as well as in macro-ergonomics evaluations, but they appear insufficient in terms of evaluating comfort.
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