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Modeling of an Integrated Internal Heat Exchanger and Accumulator in R744 Heat Pump Operation

ACRC, University of Illinois, Urbana, Il-Wenying Zhang
Univ of Illinois at Urbana-Champaign-Predrag Hrnjak
  • Technical Paper
  • 2020-01-0153
To be published on 2020-04-14 by SAE International in United States
Carbon dioxide (R744) is one of the most promising next-generation refrigerants for mobile air-conditioning applications (MAC), which has the advantages of good heating performance in cold climates and environmental-friendly properties. In this paper, a simulation model of an integrated internal heat exchanger (IHX) and accumulator (ACC) was developed using the finite volume method via EES. The results were validated by experimental results from a transcritical R744 mobile heat pump, and the error was within ±5%. The impacts of mass flow rate, evaporator outlet quality and temperatures of high- and low-side streams on the heat transfer rate, effectiveness and charge of the integrated IHX/Acc were studied. Results show that the heat transfer rate of the IHX is mostly sensitive to the evaporator outlet quality. When the evaporator quality decreases from 0.9 to 0.6, the heat transfer rate increases from 1.1 to 2.4 kW and the superheat reduces from 25.8 to 9.4 ℃. As a result, the compressor discharge temperature and the heating capacity can be reduced. To obtain the maximized capacity, especially during the startup, an…
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Validation of a Theoretical Model for the Correction of Heat Transfer Effects in Turbocharger Testing through a Quasi-3D Model

Politecnico di Milano-Gianluca Montenegro, Matteo Tamborski, Augusto Della Torre
Universita Degli Studi di Genova-Silvia Marelli
  • Technical Paper
  • 2020-01-1010
To be published on 2020-04-14 by SAE International in United States
In the last few years, the effect of diabatic test conditions on compressor performance maps has been widely investigated leading some Authors to propose different correction models. The accuracy of turbocharger performance map constitute the basis for the tuning and validation of a numerical 1D procedure, usually adopted for the engine-turbocharger matching. Actually, it is common practice in automotive applications to use simulation codes, which require as an input the value of efficiency. Therefore, the ability to correct the measured performance maps taking into account internal heat transfer would allow the implementation of commercial simulation codes used for engine-turbocharger matching calculations. The practical purpose of an adiabatic test program is to obtain an accurate measurement of the work transfer, and of the real efficiency of compressor and turbine (unaffected by internal and external heat transfer rates). In fact, the heat flow leads to an apparent increase of the power absorption and an apparent drop in efficiency of the compressor. However, lack of understanding of the heat transfer effects as well as the high costs associated…
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On-Engine Performance Evaluation of New-Concept Turbocharger Compressor Housing Design

Imperial College London-Ricardo F. Martinez-Botas
Mitsubishi Heavy Industries Engine & Tur-Motoki Ebisu
  • Technical Paper
  • 2020-01-1012
To be published on 2020-04-14 by SAE International in United States
Following the market demands in finding the niche balance between engine performance and legislation requirement, a new compressor scroll has been designed for small to medium size passenger cars. The design adopts a slight deviation from the conventional method, thus resulting in broader surge margin and better efficiency at off-design region. This paper presents the design of the new compressor scroll and its performance validation. The new compressor scroll is coupled to a standard wheel and tested on the cold gas stand followed by the on-engine testing. The testing program focused on back-to-back comparison with the standard compressor scroll, as well as identifying on-engine operational regime with better brake specific fuel consumption (BSFC) and transient performance. A specially instrumented 1.6L gasoline engine was used for this study. The engine control unit configurations are kept constant for both the compressor testing. The intake and exhaust manifold has been customized to fit the turbochargers and kept identical between the standard and new compressor scroll installations. The turbocharger with new compressor scroll design is found to work at…
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Development of Ultra-low-friction and Zero-leakage Mechanical Seal for High-Speed e-Mobility Shaft Sealing Applications

Eagle Industry Co., Ltd-Nobuo Nakahara, Masatoshi Itadani
Eagle Industry Co., Ltd.-Yuichiro Tokunaga
  • Technical Paper
  • 2020-01-1090
To be published on 2020-04-14 by SAE International in United States
By the year 2020, EU legislation limits CO2 emissions for new passenger cars to a maximum of 95 g/km, and further reductions to 68 g/km are expected. Electric motors with high power density often need shaft cooling in combination with increased rotational speeds to boost efficiency. Especially, the low friction and the durability of the sealing faces is essential to overcome the severe friction condition of the high-speed rotation. This challenge can be solved by using the revolutionary GlideXTM sealing technologies. These seals feature advanced texturing, a new surface technology that enables microscopic flow control in the dynamic sealing faces. Advanced texturing reduces leakage to the level of insignificance and up to 90% less friction, compared to a non-textured mechanical seal. The advanced texturing allows for a thin liquid-sealing film between the sealing faces. The liquid lubrication becomes dominant at low speeds; at high speeds, the gas lubrication becomes dominant by preventing the liquid from flowing into the sliding surfaces. As a result, the seal can keep low friction in both low- and high-speed rotations…
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Impact of Active-Grille Shutter Position on Vehicle Air-Conditioning System Performance and Energy Consumption in Real World Conditions

FCA Canada Inc-Pooya Mirzabeygi
FCA Canada Inc.-Shankar Natarajan
  • Technical Paper
  • 2020-01-0947
To be published on 2020-04-14 by SAE International in United States
Active grille shutter (AGS) in a vehicle provides aerodynamic benefit at high vehicle speed by closing the front-end grille opening. At the same time, this causes lesser air flow through the cooling module which includes the condenser. This results in higher refrigerant pressure at the compressor outlet. Higher head pressure causes the compressor to work more thereby possibly negating the aerodynamic benefits towards vehicle power consumption. This paper uses a numerical method to quantify the power consumed by the vehicle in different scenarios and assesses the impact of AGS closure on vehicle energy consumption. The goal is to analyze the trade-off between the aerodynamic performance and the compressor power consumption at high vehicle speeds and mid-ambient conditions. These so called real world conditions represent high way driving at mid-ambient temperatures where the air-conditioning (AC) load is not heavy. AC system which includes the refrigerant loop and vehicle cabin is modeled using 1D methodology and its performance simulated at system level. AC system performance is analyzed under steady state as well as transient conditions. Power consumption…
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Air Induction Impact on Turbocharger Noise and Thermodynamic Performance

FCA US LLC-Shadi Saeed, Brian Butler, Mark Likich, Jeff Orzechowski
FEV Europe GmbH-Tobias Zimmermann PhD
  • Technical Paper
  • 2020-01-0426
To be published on 2020-04-14 by SAE International in United States
The trend of improved FE and performance has led to industry growth of turbocharged engines and as a result, the need to address their undesirable attributes. This presents some unique engineering challenges as customer expectations for NVH, and other vehicle-level attributes, trend higher over time as well. Noise attenuation specific to turbocharged engines is uniquely challenging due to the types of noises they produce. Of specific concern, flow interaction between the induced air and compressor through a range of thermodynamic conditions can often result in objectionable "whoosh" noises within the Air Induction System (AIS). The traditional method for attenuation of this type of noise has been to use resonators which adds cost, weight and requires packaging space which is often at a premium in the under-hood environment. By improving our understanding of the root cause of the compressor whoosh noise, we hope to develop system design strategies that can prevent unwanted noise from being generated and avoid the need for traditional noise attenuation solutions. To investigate different flow metrics and their impact on compressor noise…
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EFFECT OF DEAN NUMBER ON HEAT TRANSFER CHARACTERISTICS FOR SQUARE CHANNEL HELICAL COIL SUB-COOLED CONDENSER

Keihin Corporation-Junya Washiashi, Jun Liu
Sophia University-Hardeep Singh, Mitsuhisa Ichiyanagi, Takashi Suzuki
  • Technical Paper
  • 2019-32-0597
To be published on 2020-01-24 by Society of Automotive Engineers of Japan in Japan
Attribute to high heat transfer rate and less complexity, the Helical coil sub-cooled condenser (HCSCC) can provide the most innovative and unique application for the air conditioning system. In the case of automobiles, reduction in air-conditioning load may diminish the vehicular emission, and power consumption as the air-conditioning load is the most power-consuming components after the engine load. Moreover, to solve the problem, we focus on the helical type heat exchanger. It may play a vital role in reducing the weight and increase the performance of the small engine because of the compact structure and lighter weight. The compressor unit is the most vital component of the refrigeration cycle, but the condenser unit is also one of the most critical devices, and the author tried to reduce the power consumption by enhancing the performance of the condenser. The crucial point of this study is to use HCSCC, which exemplify the effect of subsequent flow generation inside the fluid, and it is known as the Dean's effect. This effect leads to the heterogenous temperature distribution along…
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Digital Automotive AC Pulldown Prediction in a Real Driving Condition

Dassault Systemes Simulia-Vijaisri Nagarajan
Dassault Systemes, Simulia Corp-Chin-Wei Chang, Kamalesh Bhambare, Adrien Mann, Edward Tate, Abdelhakim Aissaoui
  • Technical Paper
  • 2019-01-5090
Published 2019-12-30 by SAE International in United States
Automotive Original Equipment Manufacturers (OEMs) are always striving to deliver fast Air-Conditioning (AC) pulldown performance with consistent distribution of cabin temperature to meet customer expectations. The ultimate test is the OEM standard, called “AC Pull Down,” conducted at high ambient temperature and solar load conditions with a prescribed vehicle drive cycle. To determine whether the AC system in the vehicle has the capacity to cool the cabin, throughout the drive cycle test, cabin temperature measurements are evaluated against the vehicle target. If the measured cabin temperatures are equal or lower than the required temperatures, the AC system is deemed conventional for customer usage.In this paper, numerical predictions of the cabin temperatures to replicate the AC pulldown test are presented. The AC pulldown scenario is carried out in a digital Climatic Wind Tunnel simulation. The solution used in this study is based on a coupled approach. With this method, convection is solved using PowerFLOW, a Lattice Boltzmann Method (LBM)-based flow solver, while conduction/radiation are solved using PowerTHERM thermal solver. Cooling loads, reproducing a drive cycle with…
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Rectangular Cross Section Polymeric Sealing Rings

Automatic Transmission and Transaxle Committee
  • Ground Vehicle Standard
  • J2310_201910
  • Current
Published 2019-10-09 by SAE International in United States
The purpose of this SAE Recommended Practice is to establish guidelines for the automatic transmission and hydraulic systems engineer to design rectangular cross section seals for rotating and static grooved shaft applications. Also included are property comparisons of polymeric materials suitable for these applications. Historically, material covered in this document is not intended to include aluminum contact applications.
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Increase of Compressor Performance through the Use of Microstructures

Bionic Surface Technologies GmbH-Mikel Garcia de Albeniz, Peter Adrian Leitl
RINA-Emiliano Costa, Stefano Barberis
Published 2019-10-07 by SAE International in United States
Turbomachinery efficiency is becoming more and more relevant in order to reduce fuel consumption and mechanical wear of machines at the purpose of increasing their environmental sustainability and reliability. Optimized material identification and design is therefore of paramount importance. This paper describes how turbomachines can be optimized thanks to the effect of microstructures suitably created over the shapes of their constituting components in order to increase the overall efficiency via a simple coating solution. These structures, called riblets, consist of tiny streamwise grooved surfaces which are such to reduce drag in the turbulent boundary layer. Theoretical, numerical and experimental experiences gave a first estimation of the impact of riblets in industrial compressors. In this case, the riblet structures reduce the aerodynamic shear stress losses. The areas of higher interest are the diffuser and the volute, where the higher losses happen. The optimal size, position and effect on performance were analysed via simulation. The use of such an effective numerical means may give a precise evaluation about benefits in terms of efficiency increase as well as…
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