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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
2015-01-0358
Praveen Balaj Balakrishnan, Xiaoyong Yu, Ka Chung Chan, Chi Yan Tso, Christopher Chao
An adsorption air conditioning system is proposed to provide cabin comfort cooling for automotives. This report is focused on the development of a compact adsorption cooling system for automobile applications and its experimental performance. This system uses AQSOA – Z01, an adsorbent material that adsorbs and regenerates water efficiently at low temperature ranges. A water circulation system was specially built to simulate the process of obtaining heat from exhaust gas heat and provide low-grade thermal energy for the adsorption cooling system. As this system does not need to be powered by engine as in the conventional system, it can improve fuel efficiency of the engine up to 10% which also results in reduction of pollutants due to combustion. The prototype is capable of producing up to 1310 Watts of cooling power and achieved 650 W/kg as the value for the specific cooling power (SCP) and coefficient of performance (COP) value of 0.45.
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.
2015-04-14
Technical Paper
2015-01-1254
Daishi Takahashi, Koichi Nakata, Yasushi Yoshihara, Yukinori Ohta, Hiroyuki Nishiura
In recent years, enhancing the engine thermal efficiency is strongly required. The current gasoline engine for hybrid vehicles has Atkinson cycle with high expansion ratio and cooled exhaust gas recirculation (EGR) system. The technologies contribute to raise the brake engine thermal efficiency more than 38%. It will be required that the engine thermal efficiency exceeds 40% in the near future. To enhance the engine thermal efficiency, it is essential to improve the engine anti-knock quality and to decrease the engine cooling heat loss. Therefore the cooled EGR technologies, which lead to reduce engine heat cooling loss and improve the anti-knock quality, are focused on. This paper describes that the technologies for enhancing the engine combustion technology such as high tumble which leads to the engine thermal efficiency of 40%.
2015-04-14
Technical Paper
2015-01-0330
Iman Goldasteh, Shi-Ing Chang, Salamah Maaita, Gursaran Mathur
Proper flow distribution on the windshield and side windows is critical for adequate visibility while driving. Fog or ice which forms on the windshield is the main reason of invisibility and leads to major safety issue. It has been shown that proper clear visibility for the windshield could be obtained with a better flow pattern and uniform flow distribution in the defrost mode of the HVAC system. In this study, a three dimensional numerical model of a car cabin with full HVAC system was developed using Star-CCM+, a commercial CFD package. The Reynolds-Averaged Navier–Stokes equations (RANS) approach with the realizable two-layer k-ε turbulence model was employed for simulating the airflow field on the windshield for the defrost mode. The HVAC unit, ducts and defroster grille were included in the analysis in detail and air distribution on the windshield was studied.
2015-04-14
Technical Paper
2015-01-0338
Roberto Monforte, Francesco Lovuolo, Fabrizio Mattiello, Matteo Rostagno
Dual Loop System Model: tool for performance analysis and control design Authors: F. Mattiello (CRF), R. Monforte (CRF), M.M. Rostagno (CRF), F. Lovuolo (Altran) The paper focuses on the development of a dual loop system (DLS) model. The secondary coolant loop, working at lower temperature with respect to the engine level, is exploited to cool down the charge air mass flow by means of a coolant-to-air heat exchanger and to provide heat to the HVAC circuit by means of a coolant-to refrigerant condenser. In perspective of the incoming CO2 emission regulation, the on board heat management is becoming more and more relevant to guarantee the engine performance. Other authors have outlined the effect on fuel consumption of the DLS in previous papers by means of prototype tests. The need of a prediction tool for design and performance analysis arises more and more.
2015-04-14
Technical Paper
2015-01-0340
Jan Eller, Thomas Binner, Heinrich Reister, Nils Widdecke, Jochen Wiedemann
There is a growing need for life-cycle data – so-called collectives – when developing components like elastomer bearings. Current extreme load cases are not sufficient for establishing such collectives. Consequently, the Idle load case is examined at Mercedes-Benz Car Group as a collective load case for Vehicle Thermal Management (VTM) numerical simulations in early development stages. It combines validation opportunities for HVAC, cooling and transmission requirements in hot-country-type ambient conditions. Experiments at climatic wind tunnels show steady conditions at the end of the case. With a standard Mercedes-Benz 7G transmission temperatures rise in driving gear and fall to a steady state during the subsequent section in parking gear. This effect propagates to elastomer bearings which are the focus of this study. Decoupling of the torque converter entails no dependence on transmission gear setting, anymore.
2015-04-14
Technical Paper
2015-01-0336
Amey Karnik, Daniel Pachner, Adrian M. Fuxman, David Germann, Mrdjan Jankovic, Christopher House
Numerous studies describe the fuel consumption benefits of changing the powertrain temperature based on vehicle operating conditions. Actuators such as electric water pumps and active thermostats now provide more flexibility to change powertrain operating temperature than traditional mechanical-only systems did. Various control strategies have been proposed for powertrain temperature set-point regulation. A characteristic of powertrain thermal system is that the system operating conditions change continuously to meet the driver demand. Control strategies for set-point regulation which rely purely on feedback for disturbance rejection, without knowledge of future disturbances, might not provide the full fuel consumption benefits due to the slow thermal inertia of the system. A solution to this problem is to design a control strategy that utilizes the estimate of variability of future disturbances.
2015-04-14
Technical Paper
2015-01-0341
Georg Rauch, Johannes Lutz, Martin Werner, Sagar Gurwara, Peter Steinberg
For solving problems in the field of engine heat up and thermal deformation of an engine, transient CHT analysis has gained high importance. The transient results make it possible to identify the amount of heat and its specific transfer region. Furthermore, the transient temperature profiles are used to generate the deformation fields which are crucial for friction calculations. Despite these useful applications transient CHT is avoided due to the large computational resources. This paper introduces an innovative approach which uses the synergy effect of 1D and 3D simulation in order to bring down modeling and simulation time. At the same time the methodology sustains the spatial resolution of a 3D model. This goal is reached by reducing the 3D fluid side with its time consuming continuity, momentum, energy and turbulence equations to a simple but precise 1D model. The structure stays in the 3D manner.
2015-04-14
Technical Paper
2015-01-0344
Yingchao Zhang, Weijiang Meng, Tao Chen, Yong Hao, Wei Ding
It is known that the automobile cabin thermal comfort, could keep the driver and passengers feel better which has a great effect on traffic safety. In this article, to the FAW truck cab, we did some research about the automobile cabin thermal comfort. Our plan is to calculate the air flow distribution and the temperature in steady and transient state when there is warm or cool flow. The heating and cooling experiment methods standard of cabin are based on the national standard and the automobile industry standard of China. Then the numerical simulation process becomes very important. So we used the commercial CFD code- STAR-CCM+ for study in this paper. Firstly, Geometry Clean up, we should process the cabin and the air conditioning pipe system individually, and make sure the closure of the internal surface and handle the wrap surface of the pipe.
2015-04-14
Technical Paper
2015-01-0349
Suvankar Manna, Yogendra Singh Kushwah
With stringent requirements of fuel efficiency and emissions, the airflow and thermal management within the under-hood environment is gaining significance day by day. While adequate airflow is required for cooling requirements under various vehicle operating conditions, it is also necessary to optimize it for reduced cooling drag and fan power. Hence, the need of the day is to maximize cooling requirements of Condenser, Radiator ,CAC and other heat exchangers with minimal power consumption. To achieve this objective and due to the complicated nature of 3D flow phenomenon within the under-hood environment, it is useful to perform 3D CFD studies during preliminary stages to shorten design time and improve the quality and reliability of product design. In this paper we present the results from a CFD under-hood analysis that was carried out for design, development and optimization of a CRFM (Condenser, Radiator and Fan Module).
2015-04-14
Technical Paper
2015-01-0348
Chuqi Su, Meng Xu, Naiqiang Tong, Yulian Chen
The potential for automotive exhaust-based thermoelectric generator (TEG) has been increasing with continuously advances in thermoelectric technology. In this paper, the thermal deformation of the TEG system is studied on the basis of the temperature distribution of the heat exchanger. The simulation analysis shows that the thermoelectric modules (TMs) on different positions of the heat exchanger have different thermal performance, which can significantly influence the power generation efficiency of the system. Meanwhile, it is found that the thermal performance is affected by the clamping mechanism, which has a greater effect on the cold side than the hot side. Following the simulations, bench tests are carried out to confirm the reasonability of the simulation results.
2015-04-14
Technical Paper
2015-01-0346
Lei Dongxu, Minli Bai, Jizu Lv, Peng Wang, Chengzhi Hu, Yuyan Wang
Due to the latent heat of vaporization, the efficiency of boiling heat transfer is several times and even dozens of times higher than that of the convection heat transfer. With the improvement of power density of the engine, there are more requirements for engine cooling system design. It has been confirmed that the subcooled boiling did exist in the engine cooling. If boiling heat transfer can be reasonablely used, we can achieve the objective of enhancing heat transfer without changing the existing structure. In this paper, in order to quantitatively research the subcooled boiling in the engine, we simulated the subcooled boiling in the analog channel with the Euler multiphase model, found the importance of the turbulent dispersion. In additon, we explored the applicability of existing models to subcooled boiling, and compared the results with the experiment.
2015-04-14
Technical Paper
2015-01-0350
Zhi Li, Gangfeng Tan, Jing Cai, Zhongjie Yang, YiRui Wang, Haobo Xu
Thermoelectric power generation could achieve the recovery of engine exhaust waste heat. For the conventional scheme, the hot-end of the thermoelectric module is connected with the exhaust pipe, while the cold-end is cooled through the engine cooling cycle. The variation of engine operating conditions brings the instability of the hot-end temperature, which affects the power generation performance of thermoelectric materials and increases the damage risk to the thermoelectric materials caused by the high temperature. This research adopts the heat transfer oil circulation as the intermediate fluid to absorb the dynamic heat flux of the engine exhaust so as to release the heat steadily to the hot-end of the thermoelectric module. The thermal characteristics of the target diesel engine exhaust gas are evaluated based on the experimental data firstly.
2015-04-14
Technical Paper
2015-01-0361
Yang Zou, Pega Hrnjak
Although refrigerant maldistribution among parallel microchannel tubes is mainly caused by phase separation of vapor and liquid in the header, it is also affected by pressure drop in the header. This study experimentally investigates the pressure drop of single-phase and two-phase R134a flow in the vertical header of a multi-pass microchannel heat exchanger. R134a is circulated into the transparent header through multi-parallel microchannel tubes in the bottom pass and exits through multi-parallel microchannel tubes in the top pass representing the flow in the heat pump mode of a reversible system. The pressure drop in the vertical header causes the top tube has lower mass flow rate than the lower tubes for both single-phase and two-phase flow. The overall pressure drop in the header includes four components: acceleration, gravitation, friction, and minor pressure drop due to microchannel tube protrusion.
2015-04-14
Technical Paper
2015-01-0362
Neal Lawrence, Stefan Elbel
Much attention has been given in recent years to the use of two-phase ejectors and particularly to the performance of the standard ejector cycle with a liquid-vapor separator. However, this cycle may not be the best choice for automotive applications due to the large size required by an efficient separator as well as the cycle’s performance at conditions of lower ejector potential. A limited amount of recent research has focused on alternate two-phase ejector cycles that may be better suited for automotive applications. One of these cycles, using the ejector to allow for evaporation at two different temperatures and eliminating the need for a separator, will be the subject of investigation in this paper. Previous investigations of this cycle have been mainly theoretical or experimental; this paper aims to provide a numerical analysis of the effect of evaporator design on the performance of the ejector cycles.
2015-04-14
Technical Paper
2015-01-0364
Yinhua Zheng
This paper presents the way to optimize vehicle AC system TXV to meet the various AC system requirements. It discusses vehicle AC system TXV sizing and selection process. In today’s automotive industry, sizing and selecting the TXV is more complicated than before as various new components are introduced such as external control compressor, internal control compressors and internal heat exchanger etc. These components complicated the system interaction among the components. Thus it requires mapping TXV characteristic to meet the system demand. Sizing TXV capacity, it must start with the vehicle heat load requirement. The type of TXV (i.e. cross charge or parallel charge head) is determined by the system configuration such as compressor, evaporator, and condenser type and with or without internal heat exchanger etc. In this regard, it requires mapping TXV to check the TXV behavior in the particular AC system.
2015-04-14
Technical Paper
2015-01-0399
Alexander Jaust, Bastian Morcinkowski, Stefan Pischinger, Jens Ewald
In this work, a consistent transport and mixing model is derived and validated that calculates the same mixing in thermodynamic multi-zone space as in spacially resolved physical space. The transport and mixing model is developed using a turbulent channel flow as simplified domain. This physical domain of a direct numerical simulation (DNS) is divided into zones based on the quantitative value of transported scalars. Fluxes between the zones are introduced to describe mixing from the transport equation of the probability density function based on the mixing process in physical space. The mixing process of further scalars can then be carried out with these fluxes instead of solving additional transport equations. The relationship between the exchange flux in phase space and the concept of scalar dissipation are shown and validated by comparison to DNS results.
2015-04-14
Technical Paper
2015-01-1334
Shreyas Shingavi, Pankaj Bhirud, Abhishek Ranjan
Safety and Comfort are the core requirements of the seating systems. Number of the occupants, determines type of the seating system requirement. The second row seat often needs to fold and slide, to allow the passenger to enter inside the car. Folding second row seat will also allow accommodating larger length cargo. The over folding of seat is controlled by hard stop mechanism. The hard stop mechanism generally consists of the seat arm stopper at back seat and hard stop located at base of the seat. These stoppers will limit the further motion of back seat. The folding speed of back seat is governed by various factors e.g. adjacent seat foam/structure friction, location, structural mass of seat etc. The scope of the paper is to evaluate various folding speeds of the back seat. Its effects are evaluated for the stresses and fatigue life of the hard stop components. The paper also discusses about CAE methodology used to setup the load case which replicates physical test setup.
2015-04-14
Technical Paper
2015-01-1341
Hisaki Sugaya, Yoshiyuki Tosa, Kazuo Imura, Hiroyuki Mae
When airbags deploy they break a plastic tear part of the instrument panel. Timing and the tear fracture process change the airbag’s deployment behavior. The tear fracture process is dependent on the plastic’s temperature. We developed a tear fracture simulation . Because the tear line is composed of 1mm width and 0.5mm-3.0mm flute thickness, simulating the tear fracture process is difficult, even using two models: airbag deployment, and plastic fracture. Thickness determines the tear fracture. The strain distribution of its parts should be predicted accurately. The tear fracture using solid mesh, which is 0.1mm mesh pitch, is predictable. Although it is a very complicated model and has a high computation cost, it is not applicable to the mass production development. We increase the accuracy of the tear fracture process prediction using the shell mesh, which is applicable to the mass production development.
2015-04-14
Technical Paper
2015-01-1623
Ivan Arsie, Rocco Di Leo, Stefano Falco, Cesare Pianese, Matteo De Cesare
International regulations continuously restrict the standards for the exhaust emissions from automotive engines. In order to comply with these requirements, innovative control and diagnosis systems are needed. In this scenario the application of methodologies based on the in-cylinder pressure measurement finds widespread applications. Indeed, almost all engine thermodynamic variables useful for either control and diagnosis can be derived from the in-cylinder pressure. Apart for improving the control accuracy, the availability of the in-cylinder pressure signal might also allow reducing the number of existing sensors on-board, thus lowering the equipment costs and the engine wiring complexity. The paper focuses on the detection of the engine thermal state, which is fundamental to achieve suitable control of engine combustion and after-treatment devices.
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