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2015-04-14
Technical Paper
2015-01-0442
Sudhi Uppuluri, Ajay Naiknaware
Abstract: With increasing pressure to meet CAFE standards, various strategies are being developed to actively manage the vehicle drag and engine thermal performance to squeeze out additional fuel economy performance from existing vehicle. This paper develops on the previous work presented at this conference and discusses the sensitivity of key vehicle parameters that affect the engine thermal performance and fuel economy of the vehicle. The sensitivity analysis is based on a vehicle level system model that captures the entire engine thermal model and transient behavior of various key components such as the thermostat, the active grill shutter and accessory loads. Results discussed in this paper provides guidance on which variables have the most affect on fuel economy and which variables must be tightly controlled to improve the robustness and stability of the design.
2015-04-14
Technical Paper
2015-01-1230
Ahmed Imtiaz Uddin, Jerry Ku
It is well known that thermal management is a key factor in design and performance analysis of Lithium-ion (Li-ion) battery, which is widely adopted for hybrid and electric vehicles. In this paper, an air cooled battery thermal management system design has been proposed and analyzed for mild hybrid vehicle application. Computational fluid dynamics (CFD) analysis was performed using CD-adapco’s STAR-CCM+ solver and Battery Simulation Module (BMS) application to predict the temperature distribution within a module comprised of twelve 40Ah Superior Lithium Polymer Battery (SLPB) cells connected in series. The cells are cooled by air through aluminum cooling plate sandwiched in-between every pair of cells. The cooling plate has extended the cooling surface area exposed to cooling air flow. Cell level electrical and thermal simulation results were validated against experimental measurements.
2015-04-14
Technical Paper
2015-01-0505
Miguel Angel Reyes Belmonte, Colin D. Copeland, Drummond Hislop, George Hopkins, Adrian Schmieder, Scott Bredda, Sam Akehurst
Pressure and temperature levels within a modern internal combustion engine cylinder have been pushing at the limits of traditional materials and design. These operative conditions are due to the stringent emission and fuel economy standards that are forcing automotive engineers to develop engines with much higher power density ratios. In this scenario, downsized, turbocharged engines are an important technology to meet the future demands on transport efficiency. It is well known that within downsized turbocharged gasoline engines, thermal management becomes a vital issue for durability and combustion stability. In order to contribute to the understanding of engine thermal management, a conjugate heat transfer analysis of a downsized gasoline piston engine has been performed. The intent was to study the design possibilities afforded by the use of the Selective Laser Melting (SLM) additive manufacturing process.
2015-04-14
Technical Paper
2015-01-1753
Mario Vila Millan, Stephen Samuel
Nanofluids and thermal management strategy for Automotive Application Mario Vila Millan, Stephen Samuel Oxford Brookes University, United Kingdom Stringent emission norms introduced by the legislators over the decades have forced the automotive manufacturers to improve the fuel economy and emission levels of their engine continuously. This constant improvement leads to increased use of smart systems where components are controlled by the engine management systems to get a desired and optimized performance. Therefore, the emission levels of the modern engines are significantly lower than pre-1990 engines. However, the improvement in fuel economy is marginal when compared to that of the scale of improvement achieved for reducing emission levels. For example, approximately 30% of the total energy in the fuel is still being wasted through the cooling systems in the modern engines during normal operating conditions. This is even worse during the engine warm up.
2015-04-14
Technical Paper
2015-01-1708
Tibor Kiss, Jason Lustbader, Daniel Leighton
For electric vehicles (EVs), there is a great need for highly optimized thermal management systems. Due to the relative shortage of waste heat, heating the passenger cabin in electric vehicles is difficult. Cooling the cabin can take a high portion of the energy available in the battery, significantly reducing vehicle efficiency and range. The range reduction can be as much as 50% by at least one report. Therefore, compared to IC engine driven vehicles, different heating methods and more efficient cooling methods are needed, which can make the electric vehicle’s thermal management system more complex. The more complex systems typically allow various alternative modes of operation which can be selected based on driving and ambient conditions. Investigating a number of system alternatives and determining the best ranges for the various operating modes with experimental methods can be very time consuming.
2015-04-14
Technical Paper
2015-01-1713
Manfred Klaus Kirschning, Frank Reußwig
In recent years, the automotive industry has taken many efforts to satisfy the market requirements of reducing fuel consumption and the emission of pollutants. In consequence engines had to be compacted and many additional modules had to be integrated into the confines of tightly packed engine compartments. The narrow confines also limited the options for piping options, for instance with preformed rubber tubes or oil flow and return pipes. Many of these components are designed for a maximum permanent temperature of 140°C to 180°C only. Other components, for example oil pipes, cannot be applied in settings with temperatures higher than 140°C because of the cracking of the hydrocarbon molecules.
2015-04-14
Technical Paper
2015-01-1694
Jun Li, Predrag Hrnjak
This paper presents results of the visualization of the separation in the vertical header of the automotive condenser. A prototype of a heat exchanger was made that has inlet in the middle of the header, with 21 microchannel tubes as the first pass. In the second header liquid separates and leaves through 4 microchannel tubes beneath while mostly vapor leaves through 11 microchannel tubes on the top as another exit. That way the 2nd pass has liquid below first pass and vapor above it. R134a and R1234yf are used in the tests. Mass flow was in the range 30 - 80 g/s (mass flux 170 kg/m2·s to 450 kg/m2·s) and quality at the inlet to second header over a range of 0.1 to 0.3, to see their impact on the separation of two-phase flow inside the transparent header. Visualization data were taken to better understand and define the physical parameters that dominate the separation phenomena.
2015-04-14
Technical Paper
2015-01-1710
Xinran Tao, Kan Zhou, Andrej Ivanco, John R. Wagner, Heath Hofmann, Zoran Filipi
ABSTRACT The components in a hybrid electric vehicle (HEV) powertrain include the battery pack, an internal combustion engine, and the electric machines such as motors and possibly a generator. These components generate a considerable amount of heat during driving cycles. A robust thermal management system with advanced controller, designed for temperature tracking, is required for vehicle safety and energy efficiency. This paper examines the integration of an advanced control algorithm to a HEV powertrain cooling system featuring an electric-mechanical compressor, coolant pump, three radiators, and heat exchanger and radiator fans. Mathematical models are developed to numerically describe the thermal behavior of these powertrain elements. A series of controllers are designed to effectively manage the battery pack, electric motors, and the internal combustion engine temperatures.
2015-04-14
Technical Paper
2015-01-0248
Hiroyasu Baba, Koji Kawasaki, Hideomi Kawachi
We have developed Li-ion battery heating system which is direct resistance heating for hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV) and electric vehicles (EV) by use of an inverter and a motor. One relay is added between a positive terminal of Li-ion battery and one-phase (e.g. U-phase) of a three-phase motor. When additional relay is turned on, the motor coils, IGBTs (Insulated-gate bipolar transistor) in the inverter and a smoothing capacitor for the inverter constitute buck-boost DC to DC converter. IGBTs are controlled to repeat charging and discharging between the battery and the smoothing capacitor. We made a system prototype and examined battery heating capability. And also we optimized charging and discharging frequency from impedance and current to improve heat generation. This method can increase battery temperature from -20 deg C to -1 deg C in 5 minutes and can extend EV driving range. Additionally the system can be installed into all HEV, PHEV and EV.
2015-04-14
Technical Paper
2015-01-0747
Aimin Du, Zhongpan Zhu, Chuanchuan Chu, Mengmeng Li
The research on intake, injection and mixture formation process of some gasoline direct injection engine is studied by using the CFD simulation technique. The effects of spray hole layout and injection strategy on mixture quality is also analyzed. Results show that the mixture quality can be improved with appropriate orifice layout. Using two-stage injection under condition of full load at low speed, compared to one injection, the fuel quantity impinging to wall is reduced and the cylinder turbulent kinetic energy is increased. In addition, the concentration of mixture near the spark plug is increased, which is beneficial to ignition. With more appropriate injection timing and injection ratio, the quality of mixture will be better. During cold start processes, the wallfilm can be reduced with appropriate injection timing. During hot start processes, the quality of mixture is declined with later injection timing.
2015-04-14
Technical Paper
2015-01-1301
Naoki Yoneya, Masaru Yamasaki, Atsushi Yamanaka, Kentaro Mikawa, Hidefumi Iwaki, Isao Doi
Thermal calculation 1D simulator for electric Valve Timing Control system (VTC) was developed. As for automotive engine, performance improvement such as lower emission of CO2 is more required, by recent environment regulations. Variable valve trains are essential components, and VTC is one of them. VTC can change opening and closing timing of the intake and exhaust valves into the optimum timing, depending on the driving situation. Since conventional VTC is driven hydraulically, challenges are response speed and operation limit at low temperature. For quick response and expansion of operating conditions, electric VTC is being developed. Recently, quicker response of an electric VTC is required for more efficient combustion cycles like the Atkinson Cycle. Electric VTC consists of a motor, a reduction gear, and a controller.
2015-04-14
Technical Paper
2015-01-1752
Alex Melin, David Kittelson, William Northrop
In recent years, there has been growing interest in using alternative cycles to the standard Otto cycle in an effort to improve efficiency and lower emissions of spark-ignition engines. One such proposed concept is the 5-stroke engine. The 5-stroke uses two types of cylinders, a combustion cylinder and expansion cylinder with a transfer port between them. Excess pressure in the combustion cylinder can be further expanded by using a second expansion cylinder to harness additional work; a practical implementation of the Atkinson Cycle. Since the expansion cylinder runs on a two-stroke cycle, an additional increase in efficiency can result by connecting two combustion cylinders to one expansion cylinder in a three cylinder configuration. Although previous work has investigated the performance of prototype 5-stroke engines compared to1-D modeling results, none have conducted a thorough study on the interactions of various design parameters.
2015-04-14
Technical Paper
2015-01-1711
Christian Hainzlmaier, Alejandro S. Regueiro, Marvin Lappe
Hybrid- and Electric Vehicles have a heat deficit due to frequent operation of the engine in high efficiency regions or during pure electric driving where the engine as a heat source is not available. Especially for the conditioning of the cabin, additional heat sources are necessary to ensure comfort & safety. In order to maximize the electric driving range, and improve fuel efficiency, it is important to combine a fast, efficient and safe generation of heat, with a minimum drain from the traction battery. Webasto went about this challenge and developed the new Webasto High Voltage Heater (HVH) based on a new and patented heat layer technology. This paper explains the design concept and results of the novel clean sheet research and development approach taken to achieve the project goals.
2015-04-14
Technical Paper
2015-01-1692
Walter Ferraris, Fausto Di Sciullo, Carloandrea Malvicino, Francesco Vestrelli, Fabrizio Beltramelli, Giancarlo Gotta
Automotive world is rapidly changing driven by the incoming CO2 emission regulation and the need of decreased fuel consumption for every vehicle line. The introduction of high efficiency solutions in order to get fuel consumption reduction has been already done on many vehicle systems without forgetting the cost sustainability of such solutions and with a general trend of weight reduction. For what concerns cooling systems, the increased adoption of dual level cooling loops and water cooled charge air cooling is a clear trend. The present paper proposes a compact and cost effective solution with low temperature loop cooling water cooled charge air cooler and water cooled condenser for A and B segment vehicle, with the possibility to add other exchangers to the secondary loop. All the thermal load is managed by only one radiator.
2015-04-14
Technical Paper
2015-01-1712
Ram Vijayagopal, Aymeric Rousseau
This study looks at the impact of TEGs have on different types of light duty vehicles. UDDS, Highway and Combined 2 cycle procedures are used to evaluate the fuel economy benefits in these vehicles. These fuel economy benefits are then translated to gasoline savings and net present value of the monetary benefits. Previous studies had used TEG models that depend on exhaust flow traces recorded from the test bench. A better TEG model is developed which can estimate exhaust mass flow, and respond to variations in the exhaust flow. This model can also predict the temperature variations on the hot and cold side of the TEG modules. Better TEG modules are also modelled based on the published data from General Motors (GM). The heat dissipation through the TEG between the source and sink is modelled, but various other losses like contact losses or thermal losses within the TEG are not modelled.
2015-04-14
Technical Paper
2015-01-1189
Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
A major challenge in the development of next generation electric and hybrid vehicle technology is the control and management of heat generation and operating temperatures. Vehicle performance, reliability and ultimately consumer market adoption are integrally dependent on successful battery thermal management designs. In addition to this, crucial to thermal modeling is accurate thermo-physical property input. Therefore, to design a thermal management system and for thermal modeling, a designer must study the thermal characteristics of batteries. This work presents a purely experimental thermal characterization of thermo-physical properties of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. In this research, the thermal resistance and corresponding thermal conductivity of prismatic battery materials is evaluated.
2015-04-14
Journal Article
2015-01-1184
Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
The performance, life cycle cost, and safety of electric and hybrid electric vehicles (EVs and HEVs) depend strongly on their energy storage system of vehicle. Advanced batteries such as lithium-ion (Li-ion) polymer batteries are quite viable options for storing energy in EVs and HEVs. In addition, thermal management is essential for achieving the desired performance and life cycle from a particular battery. Therefore, to design a thermal management system, a designer must study the thermal characteristics of batteries. The thermal characteristics that are needed include the surface temperature distribution, heat flux, and the heat generation from batteries under various charge/discharge profiles. Therefore, in the first part of the research, surface temperature distribution from a lithium-ion pouch cell (20Ah capacity) is studied under different discharge rates of 1C, 2C, 3C, and 4C.
2015-04-14
Technical Paper
2015-01-0355
Matthew A. Jeffers, Larry Chaney, John P. Rugh
When operated, the climate control system is the largest auxiliary load on a vehicle. This load has significant impact on fuel economy, and more importantly, it drastically reduces the driving range of electric-drive vehicles (EVs). Heating is even more detrimental to EV range than cooling, since no engine waste heat is available. Reducing the thermal loads on the HVAC system will extend driving range and increase the market penetration of EVs. Researchers at the National Renewable Energy Laboratory are evaluating strategies for vehicle climate control load reduction, with special attention toward GCEDVs. The goal is to increase EV range by 10% during operation of the climate control system. Outdoor vehicle thermal testing and computational modeling are jointly used to explore possibilities for improved thermal management and to evaluate the effectiveness of load-reduction technologies. A thermal comfort model is also being used to evaluate zonal climate control concepts.
2015-04-14
Technical Paper
2015-01-0356
Aniket Patil, Manoj Radle, Biswadip Shome, Sankar Ramachandran
Passenger comfort and safety are major drivers in a typical automotive design and optimization cycle. To address thermal comfort requirements, thermal management of the passenger cabin in a car which involves accurately predicting the temperature of the cabin interior space and the various aggregates that are present in a cabin, has become an area of active research. Traditionally, these has been done using experiments or detailed three-dimensional Computational Fluid Dynamics (CFD) analysis, which are both expensive and time-consuming. To alleviate this, recent approaches have been to use one-dimensional system-level simulation techniques with a goal to shorten the design cycle time and reduce costs. This paper describes the use of Modelica Language to develop a one-dimensional mathematical model using Dymola for automotive cabin thermal assessment when the car is subjected to solar heat loading.
2015-04-14
Technical Paper
2015-01-0354
Ji Wan Kim, Tae Hee Lee
An odor emitting from the evaporator in an air-conditioning system were analyzed that it was caused by microbial VOCs(Volatile Organic Compounds). This study about an automotive air-conditioning causing an odor is to analyze microbial diversity and community. The next-generation sequencing method was used for this analysis, which does This next-generation sequencing method, not cultivating through molecular microbiological techniques, has been developed most recently and in wide use. Moreover, this method can also analyze microorganism which has not been cultured, and produces a result which is closer to actual one in a short amount of time and a larger number of sequences. According to the analysis result about a total of 24 samples of bacterial communities, it was found that Eva core was exposed to a small number of bacteria due to its limited specificity in material and environment. The cluster analysis showed that a specific group of bacteria formed a biofilm.
2015-04-14
Technical Paper
2015-01-0360
Maryline Leriche, Wolfgang Roessner, Heinrich Reister, Bernhard Weigand
An accurate model to predict the formation of fogging and defogging which occurs for low windshield temperatures is helpful for designing the air-conditioning system in the car. Using a multiphase flow approach and additional user-defined functions within a commercial CFD-software (STAR-CCM+), a model which is able to calculate the amount of water droplets on the windshield from condensation and which causes the fogging is set up. Different parameters like relative humidity, air temperature, mass flow rate and droplet distributions are considered. Because of the condition of the windshield’s surface, the condensation occurs as tiny droplets with different sizes. The distribution of these very small droplets must be obtained to estimate numerically the heat transfer coefficient during the condensation process to predict the defogging time.
2015-04-14
Technical Paper
2015-01-0363
Vasanth Balashunmuganathan, Ramakrishna Nukala, Sathishkumar Sampath Kumar, Murali Govindarajalu
In recent years clearing the mist on side windows is one of the main criterions for all OEMs for providing comfort level to the passengers while driving. It will create poor visibility to the passengers when the mist is not cleared on side windows to the desired level. “Windows fog up excessively/don’t clear quickly” is one of the JD Power question to assess the customer satisfaction related to HVAC performance. Defrost/Demist is one of the major issues for all OEMs in recent years. In a Mobile Air Conditioning System, HVAC demister duct and outlet plays an important role for removing the mist formation on vehicle side window. Normally demister duct and outlet design is evaluated by the target airflow and velocity achieved at driver and passenger side window. Multiple flow simulation needs to be carried out for various design configurations of demister outlet until the target velocity is achieved before finalizing the design and its time consuming.
2015-04-14
Technical Paper
2015-01-0367
Zhiqiang Hu, Gangfeng Tan, Zhilei Li, Haobo Xu, Wenhui Huang, Yifan Ye
The cabin temperature increases quickly and can reach 80℃ when the vehicle parks in the summer sunlight which has the bad influence on the occupants entering comfort. Most luxury vehicles reduce the internal temperature through opening air-condition in advance or using on-board battery to drive the cabin ventilator, which requires relatively complex control system and limits the system’s working time because of energy consumption. This research adopts the solar empennage as the ventilation power supply and accomplishes the cabin real-time heat rejection by achieving the steady air circulation for both inside and outside environment. First, the static thermal transfer model of the crew cabin is established. Then, on the basis of the parameters of the prototype ventilation pipe, the ventilation model for the outside circulation is built. After that, the parameters of the solar empennage are determined according to the control target of the cabin internal temperature.
2015-04-14
Technical Paper
2015-01-0368
Janampally Sandeep Kumar Reddy, Shailendra Deopa, Abhay Sharma, Piyush Aggarwal
The condenser opening area plays a vital role in the A/C Performance of the vehicle particularly during the idling. This paper presents the detail study on the effects of the condenser opening area on the A/C performance. Based on the theory, the effect of the condenser opening area is studied and it is validated by the experimental results. Based on these results an optimum value of the condenser opening area required for the best A/C performance is concluded.
2015-04-14
Technical Paper
2015-01-0365
Gursaran D. Mathur
In a recent investigation (Mathur, 2014), the author had investigated the amount of energy stored in vehicle's Cockpit Module (CPM) at high ambient and at high solar heat loads for a MY2012 production vehicle. Detailed analysis was presented to show the influence of energy stored in various components (e.g., instrument panel, HVAC system, heat exchanger, wire harness, etc.) contained within the CPM unit. Experiments were conducted to show the amount of energy stored at high ambient and solar conditions. This is a follow up study to the above investigation. In this investigation, same vehicle is used to determine the amount of energy stored at cold temperatures, say at -20°C temperature that is used for a majority of heating, windshield and window de-fogging and de-icing tests.
2015-04-14
Technical Paper
2015-01-0366
Cristian Rostiti, Stephanie Stockar, Marcello Canova
In a scenario where the automotive industry is striving to significantly improve the fuel economy of passenger cars, it is clear that reduction of ancillary loads plays a key role for achieving significant fuel consumption and emissions reductions. In a conventional passenger vehicle, the A/C system is the largest ancillary load and it has been shown that it can consume up to 9% of the engine power available at the crankshaft This paper approaches the problem of reducing the parasitic load of the A/C system as a multi-objective optimization problem. Starting from a validated control-oriented model of an automotive A/C system, an optimization problem is formalized. Specifically, the objective of the optimization is to achieve the best possible fuel economy over a driving cycle, while guaranteeing the passenger comfort in terms of cabin temperature and reduce the wear of the components, in this case the compressor clutch.
2015-04-14
Technical Paper
2015-01-0372
Rupesh Sonu Kakade
Automotive air conditioning systems are equipped with one or two air inlet doors, controlled by one or two actuators (stepper or DC motors), to obtain desired mixing of air from inside and outside of the passenger compartment. Apart from influencing the primary objective of cabin cooling, mixing ratio between two masses of air has effect on cabin air quality - in terms of odor and pollen, oxygen and carbon dioxide levels of cabin air, window defogging and compressor load on engine. The analytical method is proposed to obtain compressor work for given cooling requirement and mixing ratio for known coefficient of performance of compressor, mass flow of evaporator air and enthalpies of air from outside and inside of the passenger compartment. The compressor work is a linear function of mixing ratio for the unsaturated evaporator outlet air and is a quadratic function for the saturated evaporator outlet air.
2015-04-14
Technical Paper
2015-01-0369
Rupesh Sonu Kakade
Apart from thermal comfort of occupants, their safety by ensuring adequate visibility is the primary objective of automotive climate control systems. Integrated dew point and glass temperature is widely used senor among several technologies to detect risk of fog formation on the windshield. The erroneous information from sensor such as the measurement lag can cause imperfect visibility due to delayed response of climate control system. A differential equation model of cabin air humidity is proposed to calculate in real-time the ambient humidity of passenger compartment. The specific humidity from the model is used to determine relative humidity for a known window surface temperature. The uniform spatial distribution of cabin air humidity is used to advantage. However non-uniform distribution of window surface temperature and the uncertainty of parameters of differential equation model are evaluated to determine risk of fogging to an acceptable accuracy.
2015-04-14
Technical Paper
2015-01-0370
Modar Horani, Osamah Rawashdeh
Traditional Heat Ventilation and Air Conditioning (HVAC) control systems are reactive by design and largely dependent on the on-board sensory data available on a Controller Area Network (CAN) bus. The increasingly common Internet connectivity offered in today’s vehicles, through infotainment and telematic systems, makes data available that may be used to improve current HVAC systems. This includes real-time outside relative humidity, ambient temperature, precipitation (i.e., rain, snow, etc.), and weather forecasts. This data, combined with position and route information of the vehicle, may be used to provide a more comfortable experience to vehicle occupants in addition to improving driver visibility through more intelligent humidity, and defrost control. While the possibility of improving HVAC control utilizing internet connectivity seems obvious, it is still currently unclear as to what extent.
2015-04-14
Technical Paper
2015-01-0878
Guanzhang He, Hui Xie
A two stage turbocharging system is adapted to simulate the power turbine that is installed downstream the charging turbine to further recover waste energy in the exhaust. The potential of energy recovery from the exhaust gas is investigated. The effect of two important controllable factors including injection timing and position of VGT (variable geometry turbocharger) vanes is studied though experiments. The overall fuel consumption benefit, fuel energy distribution, and link efficiency along the energy flow path are involved in the analysis. It is found that total power output of whole system can be enhanced when the exhaust gas is adequate corresponding to the high speed and load engine operating condition. The energy recovered will be counteracted or even less than the power loss of the original engine when low speed and load running condition is considered. The increment of pumping loss plays the dominant role in limiting the further enhancement of total power.
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