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2017-03-28
Technical Paper
2017-01-0134
Jan Eller, Heinrich Reister, Thomas Binner, Nils Widdecke, Jochen Wiedemann
There is a growing need for life-cycle data – so-called collectives – when developing components like elastomer engine mounts. Current standardized extreme load cases are not sufficient for establishing such collectives. Instead of using endurance testing data – which necessitates full vehicle on-road tests – a prediction methodology for component temperature collectives utilizing existing 3D CFD simulation models is presented. The method uses support points to approximate the full collective. Each support point is defined by a component temperature and a position on the time axis of the collective. Since it is the only currently available source for component temperature data, endurance testing data is used to develop the new method. The component temperature range in this data set is divided in temperature bands. Groups of driving states are determined which are each representative of an individual band.
2017-03-28
Technical Paper
2017-01-0623
Zun Wang, Yi Zhang, Christophe lenormand, Mohammed Ansari, Manuel Henner
Radiator thermal cycle test is a test method to check out the robustness of a radiator. During the test, the radiator is going through transient cycles that includes high and low temperature spikes. These spikes could lead to component failure and transient temperature map is the key to predict high thermal strain and failure locations. In this investigation, an accurate and efficient way of building a numerical model to simulate the transient thermal performance of the radiator is introduced. A good correlation with physical test result is observed on temperature values at various locations.
2017-03-28
Technical Paper
2017-01-0626
LeeAnn Wang, George Garfinkel, Ahteram Khan, Mayur Harsha, Prashanth Rao
When a driver completes an aggressive drive cycle on a hybrid vehicle, the High Voltage (HV) battery system may risk exceeding the power limit temperature, due to continuous absorption of radiative and convective heat from the exhaust and pavement, even after key-off. In such case, the vehicle may not be keyed-on after a certain time. A transient thermal analysis is conducted on a HV battery system to simulate the key-off operation using Computational Fluid Dynamics (CFD). The analysis is partitioned into two stages, due to complex geometry and multiple phenomena captured in the model. The first stage involves two steady-state simulations. The first simulation is to model the HV battery system, during an aggressive drive cycle. The second simulation is to model the vehicle at an idle condition immediately after the aggressive drive cycle.
2017-03-28
Technical Paper
2017-01-1239
Naoya Take, Takuya Kadoguchi, Masao Noguchi, Kimihiro Yamanaka
Power modules are used to operate three-phase alternative motors in hybrid vehicles and electric vehicles. The good fuel efficiency and high power density are requested in the field of hybrid vehicles. To achieve this goal, the miniaturization of power module will be necessary. This trend may make current density, which is operated by insulated gate bipolar transistors (IGBTs) and Free wheel diodes (FWDs), higher in power modules. Solder is often used as the joint material of power modules. It is known that a current density larger than 10 kA/cm2 causes solder electromigration which exchanges momentum from electrons to metallic atoms .This phenomenon may cause delamination of the joint area and void formation. In addition, the ambient temperature has an influence on electromigration. The temperature of an engine compartment is high, so it is likely to cause electromigration.
2017-03-28
Technical Paper
2017-01-1220
Ahmad Arshan Khan
In an electrified vehicle, magnet temperature plays a critical role in determining optimal current control trajectory of an interior permanent magnet machine. Monitoring magnet temperature is a challenging task. In lab and various specialized applications, infrared sensors or thermocouples are used to measure the temperature. But it adds cost, maintenance issues and their integration to electric machine drives could be complicated. To tackle the issues due to sensor based methods, various sensor-less model based approaches are proposed in the literature recently such as flux observer, high-frequency signal injection, and thermal models, etc. Although magnet temperature monitoring received a lot of attention of researchers, very few papers give a detailed overview of the effects of magnet temperature on motor control from a controls perspective. In this paper, we will show the effect of the change in magnet temperature on Maximum Torque per Ampere control and Flux Weakening Control.
2017-03-28
Technical Paper
2017-01-0123
Saiful Bari
In general, diesel engines have an efficiency of about 35% and hence, a considerable amount of energy is expelled to the ambient air. In water-cooled engines, about 25%, 33% and 7% of the input energy are wasted in the coolant, exhaust gas, and friction, respectively. The heat from the exhaust gas of diesel engines can be an important heat source to provide additional power and improve overall engine efficiency. Studies related to the application of recoverable heat to produce additional power in medium capacity diesel engines (< 100 kW) using separate Rankine cycle are scare. To recover heat from the exhaust of the engine, an efficient heat exchanger is necessary. For this type of application, the heat exchangers are needed to be designed in such a way that it can handle the heat load with reasonable size, weight and pressure drop. This paper describes the study of a diesel generator-set attached with an exhaust heat recovery system.
2017-03-28
Technical Paper
2017-01-0352
Zhigang Wei, Limin Luo, Richard Voltenburg, Mark Seitz, Jason Hamilton, Robert Rebandt
Thermal-fatigue performance assessment of components and systems is challenging due to the inherent complexities in mechanical and thermal loadings, material inhomogeneity, manufacturing inconsistency etc. Among all of possible failure modes, the fatigue and thermal-fatigue failures at stress raisers are of particular importance because they consist of the majority of failure modes in vehicle components and systems. Stress raisers in components include the welds, notches, and other material and geometry discontinuities. Durability and reliability assessment of stress raisers is difficult in testing because the true deformation at a stress raiser often cannot be directly measured. Many approximate engineering approaches have been developed over the last decades, but further fundamental understanding of the problems and the development of more effective engineering methods are still strongly demanded.
2017-03-28
Technical Paper
2017-01-1354
Timothy Morse, Michael Cundy, Harri Kytomaa
One potential fire ignition source in a motor vehicle is the hot surfaces of the engine exhaust system. These hot surfaces can come into contact with combustible liquids (such as engine oil, transmission fluid, brake fluid, gasoline, or diesel fuel) due to a fluid leak, or during a vehicle collision. If the surface temperature is higher than the hot surface ignition temperature of the combustible liquid in a given geometry, a fire can ignite and potentially propagate. In addition to automotive fluids, another potential fuel in post-collision vehicle fires is grass, leaves, or other vegetation. Studies of hot surface ignition of dried vegetation have found that ignition depends on the type of vegetation, surface temperature, and on the duration of contact. Ignition can occur at surface temperatures as low as 300 °C, if the vegetation is in contact with the surface for 10 minutes or longer.
2017-03-28
Technical Paper
2017-01-0260
Yuanying Wang, Heath Hofmann, Denise Rizzo, Scott Shurin
The increasing electrification of military vehicles is also increasing the need for accurate models of electric motors and generators for use in powertrain design. In particular, there is a strong need to accurately model the internal temperatures of these machines. Thus, an accurate yet computationally-efficient thermal model is required. In previous work, a technique capable of dramatically reducing the order of a 3-dimensional finite-element (FE) thermal conduction model was developed. The developed model has acceptable accuracy but is orders of magnitude faster than the FE model. This new model was validated by a locked-rotor test with close agreement, but the results are unsatisfactory when the rotor is spinning, since the resulting heat convection behavior is not precisely modeled. This paper will present a computationally-efficient model of heat convection due to air circulation produced by rotor motion.
2017-03-28
Technical Paper
2017-01-0160
Longjie Xiao, Tianming He, Gangfeng Tan, Bo Huang, Xianyao Ping
In the background of the increasing amount of car ownership in the world, the amount of heat that is not utilized in automobile exhaust should not be ignored, and the importance of using automobile exhaust gas for power generation is gradually being realized and valued by people. However, the urban traffic environment is changeable. The frequent start and stop as well as the acceleration and deceleration of the car will lead to the fluctuation of gas temperature and flow and then the temperature fluctuation of the thermoelectric module’s hot end, which reduces the power generation efficiency of thermoelectric module. By arranging the heat conduction oil circulation at the hot end, the temperature fluctuation of the hot end of thermoelectric module can be effectively reduced, but the system volume is large, and the working fluid circulation needs additional energy supply.
2017-03-28
Technical Paper
2017-01-0121
Zhijia Yang, Jesus PradoGonjal, Matthew Phillips, Song Lan, Anthony Powell, Paz Vaqueiro, Min Gao, Richard Stobart, Rui Chen
Thermoelectric generator (TEG) has received more and more attention in its application in the harvesting of waste thermal energy in automotive engines. Even though the commercial Bismuth Telluride thermoelectric material only have 5% efficiency and 250°C hot side temperature limit, it is possible to generate peak 1kW electrical energy from a heavy duty engine. If being equipped with 500W TEG, a passenger car has potential to save more than 2% fuel consumption and hence CO2 emission reduction. TEG has advantages of compact and motionless parts over other thermal harvest technologies such as Organic Rankine Cycle (ORC) and Turbo-Compound (TC). Intense research works are being carried on improving the thermal efficiency of the thermoelectric materials and increasing the hot side temperature limit. Future thermoelectric modules are expected to have 10% to 20% efficiency and over 500°C hot side temperature limit.
2017-03-28
Technical Paper
2017-01-0145
Edward Palmer, Wilko Jansen
The primary function of the brake system is to convert the kinetic energy of the vehicle to heat which is then dissipated to the environment. The performance characteristics of many of the components within the brake system are temperature dependant; with numerous issues associated with excessive temperatures such as vaporisation of the brake fluid, degradation of the friction coefficient at the disc to pad interface, thermo-mechanical deformation of the brake rotor, excessive wear and numerous NVH problems. Therefore it is clear that in order to avoid the customer encountering these failure modes the brakes must be specified with sufficient thermal inertia and cooling for the intended vehicle and drive cycle. This paper presents a high fidelity CAE technique for predicting the temperature of the front brake and the surrounding suspension components whilst installed on vehicle.
2017-03-28
Technical Paper
2017-01-0186
Cory J. Kreutzer, John Rugh, Jeff Tomerlin
Increased market penetration of electric drive vehicles (EDVs) requires overcoming a number of hurdles including limited vehicle range and the elevated cost of EDVs in comparison to conventional vehicles. Climate control loads have a significant impact on range, cutting it by over 50% in both cooling and heating conditions. In order to minimize the impact of climate control on EDV range, the National Renewable Energy Laboratory has partnered with Hyundai America and key industry partners to quantify the performance of thermal load reduction technologies on a Hyundai Sonata PHEV. Technologies that impact vehicle cabin heating in cold weather conditions and cabin cooling in warm weather conditions were evaluated. Tests included thermal transient and steady-state periods for all technologies, including the development of a new test methodology to evaluate the performance of occupant thermal conditioning.
2017-03-28
Technical Paper
2017-01-0138
Chris Lim, Peter Ireland, Nicholas Collett
The analysis of thermal fields in the underhood region is complicated by the complex geometry and the influence of a multitude of different heat sources. This complexity means that running full CFD analyses to predict the thermal field in this region is both computationally expensive and time consuming. A method of predicting the thermal field using linear superposition has been developed in order to analyse the underhood region of a simplified Formula One racecar, though the technique is applicable to all vehicles. The use of linear superposition allows accurate predictions of the thermal field within a complex geometry for varying boundary conditions with negligible computational costs once the initial characterisation CFD has been run. A quarter scale, rear end model of a Formula One racecar with a simplified internal assembly is considered for analysis, though the technique can also be applied to commercial and industrial vehicles.
2017-03-28
Technical Paper
2017-01-0534
Bojan S. Jander, Roland Baar
The knowledge of thermal behavior of combustion engines is extremely important e.g. to predict engine warm up or to calculate engine friction and finally to optimize fuel consumption. Typically, thermal engine behavior is modeled by using look-up tables or semi-physical models to calculate temperatures of structure, coolant and oil. Using look-up tables can cause in inaccurate calculation results because of interpolation and extrapolation and semi-physical modeling lead to high computation time. This study introduces a new kind of model to calculate thermal behavior of combustion engines by using artificial neural network which is high accurate and extremely fast in both building and calculating results.
2017-03-28
Technical Paper
2017-01-1240
Koki Matsushita
Demands for improving fuel economy and reducing carbon dioxide emmision in automobiles have been increasing rapidly. Since the ratio of alternator loss to entire loss of automobile is high, reducing the alternator loss is effective for fuel economy improvement. The alternator loss consists of three main losses; copper loss, iron loss and rectification loss. Above all, the ratio of rectification loss to the alternator loss, which is approximately 30%, is relatively high. DENSO has developed “MOS rectifier” to reduce the rectification loss. The MOS rectifier is a commutating device which has MOSFETs as rectifying devices instead of diodes. The MOS rectifier contributes to fuel economy improvement of automobiles by reducing rectification loss with low On-Resistance(Ron) MOSFET. Since the MOS rectifier is exposed to severe temperature environment from -40 °C to 120 °C, temperature stress on solder and Aluminium wire is large.
2017-03-28
Technical Paper
2017-01-1636
Lukas Preusser
Problem Already in the initial design failure mode analysis of this relatively young feature it became clear that an accurate sensor reading is critical to the performance of the heated steering wheel system. As the temperature reception capability of the human palm is very distinct, small deviations [≤0.1°??/??] from the targeted wheel temperature may be registered as "getting too hot" or "remaining too cold". As per industry standard, heated wheels only utilize a single sensor input to the temperature control circuitry, making it even more important for the sensor to reflect the current surface temperature. Certainly the sensor must be placed where it neither can be seen nor felt, decoupling surface from the sensor's temperature. Production tolerances for sensor placement on the heater mat along with heater mat placement tolerances relative to the armature's position add to the decoupling issue, causing unacceptably high or low steering wheel surface temperatures.
2017-03-28
Technical Paper
2017-01-1065
Douglas R. Martin, Benjamin Rocci
Paper Title: Virtual Exhaust Gas Temperature Measurement Abstract: Exhaust temperature models are widely used in the automotive industry to estimate catalyst and exhaust gas temperatures and to protect the catalyst and other vehicle hardware against over-temperature conditions. Modeled exhaust temperatures rely on air, fuel, and spark measurements to make their estimate. Inaccuracies or errors in any of these measurements have a large impact on the accuracy of the model. Furthermore, air-fuel imbalances, air leaks, ECT or ACT inaccuracies, or any unforeseen source of heat entering the exhaust may also have a large impact on the accuracy of the modeled estimate. Modern UEGO sensors have heaters with controllers in the UEGO ASIC to precisely regulate the oxygen sensing element temperature. These controllers are duty cycle based and supply more or less current to the heating element depending on the temperature of the surrounding exhaust gas.
2017-03-28
Journal Article
2017-01-0346
Radwan Hazime, Thomas Seifert, Jeremy Kessens, Frank Ju
Increasing the efficiency of heavy duty internal combustion engines is directly related to increasing specific power and, thus, increasing combustion pressure and temperature. One key component of the engine is the cylinder head which must withstand these higher temperatures and higher pressures. The path of increasing loads intensifies design conflicts, as e.g. associated with the fire deck of cylinder heads: the deck should be as thin as possible to avoid critical thermal stresses during the low frequency thermal transients but sufficiently thick to avoid failures due to the high frequency combustion pressure. A superficial solution of the design conflict is the usage of superior cast iron materials. Vermicular graphite cast iron show higher strength and fatigue resistance than the classically used lamellar graphite cast iron. However, due to their lower thermal conductivity, higher thermal stresses will arise.
2017-03-28
Technical Paper
2017-01-0164
Venkatesan Muthusamy, S. Sathish Kumar, Saravanan Sambandan
ABSTRACT In an automotive air-conditioning system, the passenger comfort in the vehicle cabin gained importance and designing a right HVAC (Heating Ventilating and Air conditioning system) unit plays a vital role during the upfront design stage. Predicting the performance of cabin cool down rate upfront in the initial design stage will help us to reduce the overall product development time. To meet the customer comfort it is necessary to validate the HVAC performance at vehicle level in the extreme hot or cold ambient conditions. The vehicle which is having higher seating capacity will have higher thermal load and providing the thermal comfort to the passenger is the challenging task for the automotive HVAC industry. The dual HVAC unit is generally used to provide uniform cooling to the larger cabin volume.
2017-03-28
Technical Paper
2017-01-1066
Christoph Beerens, Alexander Mueller, Kimm Karrip
Abstract As emissions regulations and carbon footprint are more and more demandingly controlled, thermal efficiency of engine components must be optimized. Valve group components have to allow for ever increasing temperatures, endure aggressive condensates or even contribute directly to rising efficiency and emissions demands. Even with integrated and cooled exhaust manifolds, the exhaust valves are meeting full combustion temperatures, especially for stoichiometric combustion. MAHLE has developed a new technology in order to measure valve temperatures in real time, i.e. Transient Valve Temperature Measurement (TVTM). This is a complex methodology using thermocouples installed inside of the valves, offering the possibility to run the engine at different conditions, without any functional changes in the valve train system at all. Specifically valve rotation is not affected and thus temperatures all around the valve seat can be captured during rotation.
2017-03-28
Technical Paper
2017-01-0182
Gautam Peri, Saravanan Sambandan, S. Sathish Kumar
The intended primary objective of a passenger vehicle air conditioning system is to ensure thermal comfort to the passengers seated inside at all prevailing conditions. Presently 1D analysis plays a major role in determining the conformation of the selected system to achieve the desired results. Virtual analysis thus saves a lot of time, cost and effort in predicting the system performance in the initial development phase of the vehicle HVAC systems. A variety of parameters play an important role in achieving the above thermal comfort. In order to optimize the simulation, predicting the duct losses and cabin interior temperatures plays a vital role. Physical and geometrical parameters of the cabin are accurately modelled by considering all the parameters such as glass and sheet metal surfaces, air gaps, solar angles, solar intensity, instrumentation panel, firewall etc.
2017-03-28
Technical Paper
2017-01-1388
S. M. Akbar Berry, Michael Kolich, Johnathan Line, Waguih ElMaraghy
Abstract Thermal comfort in automotive seating has been studied and discussed for a long time. The available research, because it is focused on the components, has not produced a model that provides insight into the human-seat system interaction. This work, which represents the beginning of an extensive research program, aims to establish the foundation for such a model. This paper will discuss the key physiological, psychological, and biomechanical factors related to perceptions of thermal comfort in automotive seats. The methodology to establish perceived thermal comfort requirements will also be presented and discussed.
2017-03-28
Journal Article
2017-01-0451
Klaus-Peter Heinig, David A. Stephenson, Timothy G. Beyer
Thermally sprayed coatings are used in place of iron bore liners in some aluminum engine blocks. The coatings are steel-based, and are sprayed on the bore wall in the liquid phase. The thermal response of the block structure determines how rapidly coatings can be applied and thus the investment and floor space required for the operation. It is critical not to overheat the block to prevent dimensional errors, metallurgical damage, and thermal stress cracks. This paper describes an innovative finite element procedure for estimating both the substrate temperature and residual stresses in the coating for the thermal spray process. Thin layers of metal at a specified temperature, corresponding to the layers deposited in successive thermal spray torch passes, are applied to the substrate model, generating a heat flux into the block. The thickness, temperature, and application speed of the layers can be varied to simulate different coating cycles.
2017-03-28
Journal Article
2017-01-0185
Kesavan Ramakrishnan, Pietro Romanazzi, Damir Zarko, Giampiero Mastinu, David A. Howey, Alessio Miotto
In this paper, an improved analytical model with thermal effect is described for an outer rotor surface permanent magnet machine used for in-wheel motor electric powertrain. As the in-wheel motor is operating at high torque density, it is important to estimate the winding and magnet temperatures accurately and update the winding resistance and magnet remanence at every operating point in the efficiency calculation. An electromagnetic model based on conformal mapping is used to compute the field solution. The air-gap geometry is mapped to a simpler slotless shape, where the field solution can be obtained by solving Laplace equation. The canonical domain solution is mapped back to the original domain and verified with finite element (FEM) results. The closed form solutions for core loss and magnet loss are derived from the air-gap field solutions. The copper loss is calculated by considering the proximity and skin effects.
2017-03-28
Journal Article
2017-01-0131
Chiranth Srinivasan, Chonglin Zhang, Haiyang Gao, De Ming Wang, Jody Slike
Abstract In an automotive cooling circuit, the wax melting process determines the net and time history of the energy transfer between the engine and its environment. A numerical process that gives insight into the mixing process outside the wax chamber, the wax melting process inside the wax chamber, and the effect on the poppet valve displacement will be advantageous to both the engine and automotive system design. A fully three dimensional, transient, system level simulation of an inlet controlled thermostat inside an automotive cooling circuit is undertaken in this paper. A proprietary CFD algorithm, Simerics-Sys®/PumpLinx®, is used to solve this complex problem. A two-phase model is developed in PumpLinx® to simulate the wax melting process. The hysteresis effect of the wax melting process is also considered in the simulation.
2017-01-10
Technical Paper
2017-26-0111
MY Raghu, Prashant Sharma
Abstract In recent times diesel powered vehicles are becoming popular due to improved performance and reduced exhaust emission with this the market share of diesel passenger cars expected to approach 60 % over the next few years. In compliance with future emission standards for diesel powered vehicles, it is required to use diesel particulate filters (DPF) along with other exhaust emission control devices. There is a need for more optimized DPF cell structure to collect maximum soot load with low pressure drop and improved exhaust performance from diesel vehicles in Indian driving conditions. In this thesis paper a detailed parametric study have been carried out on different DPF cell structures like Square, Hexagonal and combined cell geometry. The performances of different cell structure has been evaluated for maximum soot loading capacity and regeneration rate, pressure drop, temperature distribution across cell structure.
2017-01-10
Technical Paper
2017-26-0322
Saktheeswaran Kasinathan, Sreenivasa Gupta, Husain Agha, Rajiv Modi
Abstract In any industry, early detection and mitigation of a failure in component is vital for feasible design changes or development iterations or saving money. So it becomes pivotal to capture the failure mode in an accelerated way. This theory poses many challenges in devising the methodology to validate the failure mode. In real world, vehicle head lamp is exposed to all possible kinds of harsh environments such as variable daily ambient, rain, dust and engine compartment temperature …etc. This brings rapid thermal stress onto headlamp resulting into warpage cracks. At vehicle level on particular model, this failure is typically observed after 20,000-25,000 kms in a span of 3-4 months of running. Any corrective action to revalidate the design change or improvement will need similar timelines in regular way to test, which is quite high in product development cycle.
2017-01-10
Technical Paper
2017-26-0299
Mahesh Kishore Patekar, Jeevan Patil, Sivakumar Palanivelu, Bhupendra Bhat
Abstract Brake system is the most important system in the vehicle considering the overall vehicle safety and speed control. Brake applications are repetitive during a city traffic and hilly terrain on downhill gradient. Frequent braking gives rise to an overheating of the brake drum and its components. Braking operations at high temperature gives rise to problems like reduced deceleration due to loss of brake pad friction characteristics, pad softening and sticking to drum, pad distortion and wear etc. All these factors collectively result in deterioration of the braking performance and reduction of brake pad durability with time. Till date most of the thermal analysis performed for brake drum heating are through physical testing using brake system prototypes and by means of CFD tools. These methods are time consuming and expensive. There is a need for an alternative method to reduce physical trials and prototype building and reduce dependency on CFD analysis.
2017-01-10
Technical Paper
2017-26-0292
Irshad Mahammad, Vinay Nagaraj, Saurabh Prabhakar
Abstract To replicate on-road brake test cycle of cooling or heating through Computational Fluid Dynamics (CFD) simulations, the vehicle model with brake assembly must be solved in transient mode. However, such simulations require significant computational time owning to the physics involved in computing the variation of temperature with time. A methodology developed using commercial CFD tools to predict the Heat Transfer Coefficient (h), Cooling Coefficient (b) and rotor temperatures is described in this paper. All the three modes of heat transfer: conduction, convection and radiation are considered in the current method. Heat transfer coefficients from the CFD simulations are exported to Computer Aided Engineering (CAE) tools to validate the Brake Rotor Thermal Coning caused by high thermal gradients in brake rotor.
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