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Methodology to quantify the undesirable effects of the localized inefficiency of heat pick-up in suction line on an automotive air-conditioning system

Y.S.Sarath Reddy
Tata Motors Ltd-Suresh Tadigadapa, Santosh Ghorpade, Ankit Shukla
  • Technical Paper
  • 2020-28-0036
To be published on 2020-04-30 by SAE International in United States
The automotive application places very special demands on the air conditioning system. As is the case with any other process, system efficiency is very important and the automotive air-conditioning application is no exception. While the characteristics of all the major components in the air conditioning system like compressor, condenser, evaporator and blower contribute to overall system efficiency, localized inefficiencies do play a part and so must be kept to a minimum, especially in this day and age when extra emphasis is being paid on sustainability. One such phenomenon that contributes to the system inefficiency is heat pick-up in suction line. Since the temperature at the evaporator-outlet is quite lower than ambient and also its surroundings (steering system pipes and hoses, engine, air intake pipes and so on), the refrigerant picks up heat as it moves along the suction line up to the compressor inlet. This heat pick-up is detrimental to the overall system performance. Even though most of the automotive HVAC engineers are fairly aware of the undesirable effects of heat pick-up in suction line,…
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Thermal Analysis of Clutch Assembly Using Co-Simulation Approach

Mahindra & Mahindra Ltd-Tanmay Sushant Santra, Nagarajan Gopinathan, Kumar Raju, Ganesh Sugumar, Udaya Paradarami, Vikraman Vellandi
  • Technical Paper
  • 2020-28-0024
To be published on 2020-04-30 by SAE International in United States
Automotive clutches are rotary components which transmits the torque from the engine to the transmission. The flywheel lining rotates with the engine, and the pressure plate is rotating with the transmission input shaft, both parts are rotating at different speeds, dependent on the engine speed and the engaged gear ratio. During the engagement, due the difference in speed of the shafts the friction lining initially slips until it makes a complete engagement. Enormous amount of heat is generated due to the slippage of the friction lining, leading to poor shift quality & clutch failure. Depending on the road & traffic conditions, & frequency of engagement and disengagement of the clutch, it generates transient heating & cooling cycles. The friction coefficient drops sharply until it cannot pass valid torque once temperature exceeds the threshold value. This further worsen clutch slippage and lead to more severe temperature rise. To preform transient CFD simulation, co-simulation methodology is applied, for the clutch to predict operating surface temperature of both pressure, flywheel & air temperature for hill holding with maximum…
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Direct Yaw Moment Control of Electric Vehicle with 4 In-Wheel Motors to Improve Handling and Stability

China FAW Group Corporation-Jinlong Cui, Zehui Zhou, Yang Fang, Deping Wang, Tianqiang Zhang, Aibin Wu, Qichun Sun, Yang Zhao
College of Automotive Engineering Jilin University-Yongqiang Zhao
  • Technical Paper
  • 2020-01-0993
To be published on 2020-04-14 by SAE International in United States
More and more OEMs are interested in in-wheel-motor drive vehicles. One of the in-wheel-motor drive vehicle key technologies is multi-motor torque distribution. A direct yaw moment control strategy for torque distribution was introduced in this paper to improve 4 in-wheel-motor electric vehicle’s handling and stability. The control method consists of three components: feedback control based on target yaw rate, feedforward control based on current lateral acceleration and deceleration control based on under/oversteer situation. Feedback control is used to make vehicle’s real yaw rate following the driver’s target yaw rate and improve vehicle yaw rate response and stability. The target yaw rate is calculated by 2DOF vehicle model and limited by lateral acceleration and vehicle current steering condition. The feedforward control is used to increase the vehicle yaw rate gain and reduce the vehicle understeer characteristic when accelerating in a curve. The deceleration control can reduce the driving torque of each motor to slow down the vehicle when in critical steering condition. The proposed control strategy was verified by an in-wheel-motor drive electric vehicle test and…
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Modeling of an Integrated Internal Heat Exchanger and Accumulator in R744 Mobile Air-Conditioning Applications

University of Illinois at Urbana-Champaign-Wenying Zhang, Predrag Hrnjak
  • Technical Paper
  • 2020-01-0153
To be published on 2020-04-14 by SAE International in United States
Carbon dioxide (CO2 or R744) is a promising next-generation refrigerant for mobile air-conditioning applications (MAC), which has the advantages of good heating performance in cold climates and environmental-friendly properties. This paper presents a simulation model of an integrated internal heat exchanger (IHX) and accumulator (Acc) using the finite volume method. The results are validated by a group of experimental data collected with different transcritical R744 mobile air-conditioner and heat pump (MHP) systems, and the error was within ±10%. The impacts of refrigerant mass flow rate and operating temperatures on the heat transfer rate of the IHX, improvement on refrigeration capacity and the liquid level in the Acc were studied. Results show that the net benefits of IHX are significant in AC mode, while it helps preventing flooding of the compressor in MHP mode. Also, the IHX heat transfer performance is more sensitive to evaporator exit quality and operating temperatures than it is to relative mass flow rate. The flow and liquid level in the accumulator is also described by the model.
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Ramped Versus Square Injection Rate Experiments in a Heavy-Duty Diesel Engine

DAF Trucks NV-Bogdan Albrecht
Delphi Technologies-Tony Simpson
  • Technical Paper
  • 2020-01-0300
To be published on 2020-04-14 by SAE International in United States
CO2 regulations on heavy-duty transport are introduced in essentially all markets within the next decade, in most cases in several phases of increasing stringency. To cope with these mandates, developers of engines and related equipment are aiming to break new ground in the fields of combustion, fuel and hardware technologies. In this work, a novel diesel fuel injector, Delphi’s DFI7, is utilized to experimentally investigate and compare the performance of ramped injection rates versus traditional square fueling profiles. The aim is specifically to shift the efficiency and NOx tradeoff to a more favorable position. The design of experiments methodology is used in the tests, along with statistical techniques to analyze the data. Results show that ramped and square rates - after optimization of fueling parameters - produce comparable gross indicated efficiencies. Tests were carried out at 1200 and 1425 rpm; for the latter engine speed peak efficiency was attained at considerably lower NOx levels by applying a ramped injection rate. Particulate matter emissions, on the other hand, are generally lower with the use of square…
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Modelling and Control of Multi-Vehicle Traffic Networks Using an Integrated VISSIM-Matlab Simulation Platform

University of North Carolina Charlotte-Shubhankar Chintamani Shindgikar, Pouria Karimi Shahri, Amir H. Ghasemi
  • Technical Paper
  • 2020-01-0887
To be published on 2020-04-14 by SAE International in United States
This paper aims to develop a platform for integrating PTV VISSIM and MATLAB Simulink to design and analyze the flow of traffic in an urban traffic network. We model a non-signalized traffic network in VISSIM. From VISSIM, we take the inflow and outflow rates data and send them to the controller in MATLAB through a VISSIM Component Object (COM) interface. By employing an extremum seeking approach, an optimal velocity is determined and sent back to VISSIM through the COM interface. Numerical simulation demonstrates the effectiveness of the platform for testing different traffic control approaches and optimizing flow.
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Development of the Defrost Performance Evaluation Technology in Automotive Using Design Optimization Analysis Method

Hyundai Mobis-Hyeonseok Seo, Jinwon Seo, Bongkeun Choi
  • Technical Paper
  • 2020-01-0155
To be published on 2020-04-14 by SAE International in United States
In this study, we developed the defrost performance evaluation technology using the multi-objective optimization method based on the CFD. The defrosting is one of the key factors to ensure the drivers’ safety using the forced flow having proper temperature from HVAC during drive. There are many factors affecting the defrost performance, but the configurations of guide-vane and discharge angles in the center DEF(defrosting) duct section which are main design factors of the defrost performance in automotive, so these were set to the design parameters for this study. For the shape-optimization study, the discharge mass flow rate from the HVAC which is transferred to the windshield and the discharge areas in the center defrost duct were set to the response parameters. And then, the standard deviation value of mass flow rate on the selected discharge areas checking the uniformity of discharge flow was set to the objective function to find the optimal design. The results on the windshield from optimization analysis were quantified from some kind of standards to evaluate the defrost performance, in particular, the…
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The Study on the Influence of Factors on Vehicle Refueling Emission Test

China Automotive Technology and Research-Chunbei Dai, Taiyu Zhang, Chongzhi Zhong, Qiang Chen, Jiaxing Sun, Xiaoliang Wu, Tiefei Yu
  • Technical Paper
  • 2020-01-1070
To be published on 2020-04-14 by SAE International in United States
Two vehicles with ORVR system which are met with the US standard were studied. A comparative of refueling emissions test under different refueling rate and different refueling temperature were studied. The HC chemical analysis was carried out for the fuel gas emission from a sample car. The results show that with the increase of the refueling rates, the refueling emissions decline at first, and then gradually stabilize; with the increase of the refueling temperature, the results of refueling emissions show a gradual increase. Under the condition of 37 L / min refueling flow rate and 20 °C fuel temperature, 14 kinds of alkanes are emitted from the fuel, in which isobutane, isopentane and n-pentane are the highest emissive components, accounting for 57.66% of the total amount of VOCs.
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Study of Thermal Efficiency Improvement by Multi-Hole Nozzle

Hino Motors Ltd.-Kazunori Yoshitomi, Yoshihiro Funayama, Mori Ishii, Hiroshi Nakajima
  • Technical Paper
  • 2020-01-0304
To be published on 2020-04-14 by SAE International in United States
A truck and bus transportation which support logistics and people, diesel engines are highly expected to have high thermal efficiency and low exhaust emissions over the next few decades. Effective methods to achieve even higher thermal efficiency are to reduce a cooling loss from combustion chamber wall. A multi-hole diesel injector has a significant impact on improving engine thermal efficiency by enhancing a combustion activity and reducing a cooling loss. In this study, two types of diesel injectors - 8-hole and 14-hole - with the same flow rate were tested under heavy-duty diesel engine condition. Heat release rate, energy balance and engine emissions were investigated using the single-cylinder engine with displacement of 1,478 cc. Furthermore, an optical engine was used to observe quantitative spray penetration and flame development from shadowgraph imaging and analyze flame temperature by a two-color method. The results of the single-cylinder engine showed that the 14-hole injector exhibited higher indicated thermal efficiency thanks to lower cooling loss than 8-hole results. However, we observed a slightly higher exhaust loss in the case of…
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A Gear Shifting Indication Strategy of Eco-Driving Vehicle

Jiangsu University-Nannan Hu
Jiangsu University-Ren He
  • Technical Paper
  • 2020-01-0966
To be published on 2020-04-14 by SAE International in United States
The current indication strategies of gear shifting indication system for manual transmission vehicles are developed based on the gear shifting strategies of the automatic transmission vehicles. In this paper, it is found that the gear shifting frequency of automatic transmission vehicles is significantly higher than that of manual transmission vehicles based on the collected driving data of several automatic transmission and manual transmission vehicles, which increases the fatigue of drivers. Aiming at this problem, this paper proposes an interval algorithm of gear shifting indication strategy based on the fuel consumption rate of engine, which uses genetic algorithm to process the data of fuel consumption rate to find the maximum and minimum values ​​in the interval of torque and engine speed and adopts the interval algorithm to transform the search of least fuel consumption value into the seeking of optimal interval to avoid the shift busyness caused by the sudden change of fuel consumption rate. The gear shifting tolerance is defined to avoid the shift busyness while the evaluation function values for a pair of adjacent…