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Assessment of Energy Consumption and Range in Electric Vehicles with High Efficiency HVAC Systems Based on the Tesla Expander

University of Brescia-Paolo Iora, Alberto Cassago, Costante Invernizzi, Alessandro Copeta, Gioele Di Marcoberardino, Stefano Uberti
University of Florence-Daniele Fiaschi, Lorenzo Talluri
Published 2019-10-07 by SAE International in United States
Battery electric vehicles (BEVs) are considered one of the most promising solution to improve the sustainability of the transportation sector aiming at a progressive reduction of the dependence on fossil fuels and the associated local pollutants and CO2 emissions.Presently, the major technological obstacle to a large scale diffusion of BEVs, is the fairly low range, typically less than 300 km, as compared to classical gasoline and diesel engines. This limit becomes even more critical if the electric vehicle is operated in severe weather conditions, due to the additional energy consumption required by the cabin heating, ventilating, and air-conditioning (HVAC).The adoption of vapor-compression cycle, either in heat pump or refrigerator configuration, represents the state-of-the-art technology for HVAC systems in vehicles. Such devices typically employ an expansion valve to abruptly reduce the pressure causing the flash evaporation of the working fluid. This component, although necessary to provide the cooling effect, is also responsible of a significant exergy loss, which reduces the efficiency of the thermodynamic cycle.In this paper we study the possible benefits in terms of energy…
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SAE Aerospace Applied Thermodynamics Manual Aerothermodynamic Systems Engineering and Design

AC-9 Aircraft Environmental Systems Committee
  • Aerospace Standard
  • AIR1168/3A
  • Current
Published 2019-09-24 by SAE International in United States

This document is one of 14 Aerospace Information Reports (AIR) of the Third Edition of the SAE Aerospace Applied Thermodynamics Manual. The manual provides a reference source for thermodynamics, aerodynamics, fluid dynamics, heat transfer, and properties of materials for the aerospace industry. Procedures and equations commonly used for aerospace applications of these technologies are included.

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Energy Recovery Rate from an Electric Air-Cycle System under the Cruising Altitude and Speed

Akita University-Takahiro Adachi, Mikio Muraoka
IHI Corporation-Naoki Seki, Hitoshi Oyori
Published 2019-09-16 by SAE International in United States
A new electric air-cycle system of aircrafts is investigated focusing on energy recovery from the exhaust air. The working fluid of air has the higher energy level in the cabin than in the outside during the cruise because the outside air is at low pressure and low temperature. In the system, by setting a recovery turbine behind the cabin, the discharged energy can be collected, although the working fluid through the system has been only discharged from the cabin into the outside. We perform a thermodynamic cycle-analysis, where the temperature, pressure, entropy, etc. are calculated at each position of the cycle by considering the two pressure ratios of the compressors as variable parameters to show T-s diagram. In addition, we obtain an energy recovery rate of the recovery energy to the necessary power for the electric compressor. The energy recovery rate is roughly estimated 40-80% under the reasonable practical operating conditions.
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Global Temperature Mapping and Crystallization Analysis of Supercooled Water Droplet Freezing Using Luminescent Imaging Technique

University of Notre Dame-Wesley Chad Patterson, Hirotaka Sakaue
Published 2019-06-10 by SAE International in United States
A prominent environmental phenomenon that greatly affects many industries including automotive, aeronautics, energy transmission, etc. is icing. One mechanism by which this occurs and plagues our machines and infrastructures that are exposed to the atmosphere is the icing of supercooled water droplets on a surface - either by impact against a surface or spontaneous nucleation and crystallization of a droplet at rest. The process by which nucleation propagates during the liquid-to-solid phase change and the thermodynamic implications in regards to latent heat generation and transfer are not fully understood on the single droplet scale. An attempt to better resolve these unknowns in both spatial and temporal domains has been made here. Previous efforts have implemented a unique temperature sensing technique utilizing luminescent dyes. A thermally sensitive luminescent paint coated onto the surface of interest allows direct mapping of the heat transfer from the supercooled liquid droplet undergoing freezing to the surface. This technique also provides insight into the nucleation propagation speed along the droplet-substrate interface. This, in conjunction with a high-speed color camera and an…
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Analysis of Experimental Ice Accretion Data and Assessment of a Thermodynamic Model during Ice Crystal Icing

NASA Glenn Research Center-Peter M. Struk
Ohio Aerospace Institute-Tadas P. Bartkus, Jen-Ching Tsao
Published 2019-06-10 by SAE International in United States
This paper analyzes ice crystal icing accretion data and evaluates a thermodynamic ice crystal icing model, which has been previously presented, to describe the possible mechanisms of icing within the core of a turbofan jet engine. The model functions between two distinct ice accretions based on a surface energy balance: freeze-dominated icing and melt-dominated icing. Freeze-dominated icing occurs when liquid water (from melted ice crystals) freezes and accretes on a surface along with the existing ice of the impinging water and ice mass. This freeze-dominated icing is characterized as having strong adhesion to the surface. The amount of ice accretion is partially dictated by a freeze fraction, which is the fraction of impinging liquid water that freezes. Melt-dominated icing occurs as unmelted ice on a surface accumulates. This melt-dominated icing is characterized by weakly bonded surface adhesion. The amount of ice accumulation is partially dictated by a melt fraction, which is the fraction of impinging ice crystals that melts. Experimentally observed ice growth rates suggest that only a small fraction of the impinging ice remains…
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Modeling Fuel Tank Draining/Sloshing in a Typical Transiently Accelerating Vehicle using GT-SUITE for Reliable Tank Designing

Gamma Technologies LLC-Arpit Tiwari, Nils-Henning Framke
Published 2019-04-02 by SAE International in United States
Draining and fuel starvation prediction is of critical importance in designing and approving fuel tanks. Simulation of fluid dynamics to predict draining of a moving tank having multiple fuel compartments and multiple ports is, however, challenging. This is because the dynamics involve multiple fluids which follow distinct thermodynamics - compressible air at the top and nearly incompressible fuel below it. Moreover, for a typical vehicle accelerating transiently in a general trajectory (road profile), the surface angle keeps changing which leads to dynamic fuel covering/uncovering of interior as well as outlet ports. Simulation of these effects often requires 3D multiphase solution, which is computationally expensive especially when it is required to model additional fluid systems such as fuel pipes and jet pumps. We present fast and efficient modeling and simulation of tank draining using the 0D/1D framework of GT-SUITE. The flexibility and robustness of the inbuilt flow solver allows accurate solution of the associated multiphase flow dynamics. Furthermore, the software is geometrically flexible to capture the surface angle variations (sloshing) inside complicated 3D shaped tanks in…
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A Computational Study on Laminar Flame Propagation in Mixtures with Non-Zero Reaction Progress

Oakland University-Han Lin, Peng Zhao
Texas Tech University-Haiwen Ge
Published 2019-04-02 by SAE International in United States
Flame speed data reported in most literature are acquired in conventional apparatus such as the spherical combustion bomb and counterflow burner, and are limited to atmospheric pressure and ambient or slightly elevated unburnt temperatures. As such, these data bear little relevance to internal combustion engines and gas turbines, which operate under typical pressures of 10-50 bar and unburnt temperature up to 900K or higher. These elevated temperatures and pressures not only modify dominant flame chemistry, but more importantly, they inevitably facilitate pre-ignition reactions and hence can change the upstream thermodynamic and chemical conditions of a regular hot flame leading to modified flame properties. This study focuses on how auto-ignition chemistry affects flame propagation, especially in the negative-temperature coefficient (NTC) regime, where dimethyl ether (DME), n-heptane and iso-octane are chosen for study as typical fuels exhibiting low temperature chemistry (LTC). The computation of laminar flame speed of lean and stoichiometric mixtures of fuel/air was performed at different ignition reaction progress, by selecting the thermal chemical states corresponding to different residence times during auto-ignition as the flame…
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Exergoeconomic Analysis and Modelling of LM2500+G4 Engine for Marine Propulsion and Cogeneration Application

C. V. Raman College of Engg. Bhubaneswar-Aishi Sahu
GVP College of Engineering (Autonomous)-Mithilesh Kumar Sahu
  • Technical Paper
  • 2019-01-0903
Published 2019-04-02 by SAE International in United States

The current global energy scenario demands for fuel efficient and cost effective thermal systems of energy conversion. It leads to investigation of techniques which can minimize the energy wastage and maximize the utilization of energy. In this regard the present paper proposes a configuration (LM2500+G4 marine engine manufactured by M/S GE Aviation for cogeneration application) for marine propulsion and cogeneration. The exhaust gas temperature of LM2500+G4 marine engine is around 800 K hence heat of this exhaust stream can be utilized to produce process steam for further use. In this particular work the aforesaid configuration has been exergoeconomically analyzed to predict the total cost rate (investment cost rate + fuel cost rate) of the system. The “Average Cost Theory” has been approached for the exergoeconomic analysis. The exergoeconomic analysis is the combined study of thermodynamic concepts and economic principles. Methodology utilizes the exergy concept of thermodynamics for cost assignment which is why it is called as “Exergoeconomic Analysis”. The present work deals with the thermodynamic performance prediction of proposed engine configuration as well as it also reveal the cost related data of the same. The results obtained from exergoeconomic analysis show that by generating steam in heat recovery steam generator the exergetic efficiency of cycle has been improved by 40%. The result of analysis also shows that investment cost flow rate ( Z. ), cost rate of fuel ( C.f ), total cost flow rate ( C.T ) and exergetic efficiency (ε) is being 0.2822 $/s, 0.3490 $/s, 0.6313 $/s and 53.90 % respectively.

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Effect of Thermodynamic Conditions on Spark Ignition to Compression Ignition in Ultra-Lean Mixture Using Rapid Compression Machine

Tsinghua University-Qinhao Fan, Yunliang Qi, Zhi Wang
Published 2019-04-02 by SAE International in United States
Compression ratio and specific heat ratio are two dominant factors influencing engine thermal efficiency. Therefore, ultra-lean burn may be one method to deal with increasingly stringent fuel consumption and emission regulations in the approaching future. To achieve high efficiency and clean combustion, innovative combustion modes have been applied on research engines including homogeneous charge compression ignition (HCCI), spark-assisted compression ignition (SACI), and gasoline direct-injection compression ignition (GDCI), etc. Compared to HCCI, SACI can extend the load range and more easily control combustion phase while it is constrained by the limit of flame propagation. For SACI with ultra-lean burn in engines, equivalence ratio (φ), rich-fuel mixture around spark plug, and supercharging are three essentials for combustion stability. In order to investigate the effect of flame propagation and thermodynamic conditions on ultra-lean combustion, SACI experiments using lean iso-octane mixture were carried out in a rapid compression machine (RCM) together with high-speed photography to capture flame propagation and reaction front, which indicate combustion modes under various thermodynamic conditions. Knocking intensity (KI) was used to evaluate heat release degree…
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Optical Experiments on Strong Knocking Combustion in Rapid Compression Machines with Different Fuels

Chinese Academy of Sciences-Tao Li
Tianjin University-Zhen Hu, Jaying Pan, Haiqiao Wei, Guobin Ma, Changwen Liu
Published 2019-04-02 by SAE International in United States
Nowadays the strong knocking combustion involving destructive pressure wave or shock wave has become the main bottleneck for highly boosted engines when pursuing high thermal efficiency. However, its fundamental mechanism is still not fully understood. In this study, synchronization measurements through simultaneous pressure acquisition and high-speed direct photography were performed to comparatively investigate the strong knocking combustion of iso-octane and propane in a rapid compression machine with flat piston design. The pressure characteristics and visualized images of autoignition and reaction wave propagation were compared, and the correlations between thermodynamic trajectories and mixture reactivity progress were analyzed. The results show that iso-octane behaves a greater propensity to strong knocking combustion than propane at similar target pressures. Visualized images show that strong knocking combustion results from secondary autoignition and subsequent supersonic reaction wave propagation. Further analysis on thermodynamic trajectories shows that the secondary autoignition may closely correlate with the negative temperature coefficient behavior controlled by low-temperature chemistry.
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