bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on the Autoignition Characteristics of Gasoline-Biodiesel Blended Fuel Using a Rapid Compression Expansion Machine
Authors: Jwa Kyeonghun , Lee JinWoo , Lim Ocktaeck 
Published: December 2019

Abstract
In this study, the problem of GCI method at low intake air temperature was solved by using gasoline-biodiesel blended fuel. Autoignition characteristics of gasoline-biodiesel blended fuel was analyzed using a rapid compression expansion machine. Gasoline-biodiesel blended fuel was mixed 20% of biodiesel with gasoline volume and spontaneous ignition characteristics were analyzed according to fuel injection timing and compression ratio. Firstly, this study investigated spontaneous ignition characteristics of gasoline-biodiesel blended fuel according to the injection timing. A compression ratio was fixed at 12, and the injection timing was delayed from −49° CA ATDC to 0° CA ATDC. The ignition delay time of the mixed fuel was decreased and the IMEP was increased as the injection timing was delayed until −10° CA ATDC. However, the ignition delay time and IMEP subtly changed when the injecting was near TDC. To investigate the auto-ignition characteristics of the gasoline-biodiesel blended fuel according to the compression ratio, the experiment tested at 10, 12, 14, and 16. At that time, the injection timing was set to −33° CA ATDC, −20° CA ATDC, −10° CA ATDC, and −0° CA ATDC. The ignition delay tended to be shorter as the injection timing was delayed at all compression ratios but IMEP calculated at CR10, 16 is good at only specific injection periods. At the compression ratios 12 and 14, the most extensive range of IMEP results were obtained.
Mathematical Modeling of Electrical Heater Assisted CO Conversion in an Oxidation Catalyst at Low Loads and Cold Start Conditions
Authors: Nair Sreeharsh , Mohapatra Priyabrata , Mittal Mayank 
Published: December 2019

Abstract
The emission regulations for internal combustion engines are becoming more and more stringent with the aim to reduce the pollutants emitted to the atmosphere. One of the most efficient means to meet upcoming stringent emission regulations is by reducing the pollutants emitted during the warm-up time and at low-load operating conditions by using an oxidation catalyst. In the present work, a 1-D mathematical model of an electrical heater assisted oxidation catalyst has been developed to study the effect of heater on CO conversion at low operating loads and during cold start conditions. The study has been conducted considering different power levels, heating durations (continuous and temporary) and heating volumes, and it promises to be helpful in tackling the problem. The results revealed that heater assistance to the oxidation catalyst improved the light-off performance, and temporary heating was found to be as effective as continuous heating in reducing the CO emission. Moreover, an indication parameter (light-off time reduction per unit power) has been developed, which can be used to optimize the power requirement of the heater.
Diesel Engine Acoustic Diagnostics With Machine Learning During Various Degradation Modes
Authors: Moore Patrick , Prak Dianne Luning , Hamilton Len , Cowart Jim 
Published: December 2019

Abstract
A diesel engine electrical generator set (‘gen-set’) was instrumented with an in-cylinder pressure indicating system as well as an acoustic emission sensor near the engine. Air filter clogging, rocker arm gap and fuel cetane changes were applied during which engine combustion and acoustic data were collected. Fast Fourier Transforms (FFTs) were analyzed on the acoustic data. FFT data were then applied to categorical supervised machine learning neural network analysis with MATLAB based tools. The detection of the various degradation modes was audibly determined with correlation coefficients greater than 99% on test data. Next, an unsupervised machine learning Self Organizing Map (SOM) was produced during normal-baseline operation of the engine.
Application of the degraded mode engine sound data from operation with the various faults were then applied to the normal-baseline SOM. The quantization error of the various degraded engine data showed clear statistical differentiation from the normal operation data map. This unsupervised SOM based approach does not know the engine degradation behavior in advance, yet shows promise as a method to monitor and detect changing engine operation. Companion in-cylinder combustion data shows how changing combustion characteristics result in emitted sound differences.
Combustion and Greenhouse Gas Emissions of a Natural Gas-Diesel Dual Fuel Engine at Low and High Load Conditions
Authors: Guo Hongsheng , Liko Brian , Littlejohns Jennifer 
Published: December 2019

Abstract
The Paris agreement is exerting pressure on industries that generate significant greenhouse gas (GHG) emissions, such as transportation. Electrification can help reduce GHG emissions from light duty vehicles, but it is unfeasible for heavy duty vehicles that are predominately powered by diesel engines. Fuel switching from diesel to low carbon fuels is a more practical way helping reduce GHG emissions from heavy duty vehicles. Natural gas and renewable natural gas are low carbon or renewable fuels that generate much less carbon dioxide (CO2) emissions than diesel during combustion. Natural gas/renewable natural gas – diesel dual fuel combustion is an efficient way to replace diesel by natural gas/renewable natural gas in heavy duty diesel engines.
This paper reports an experimental investigation on combustion and GHG emissions of a heavy duty natural gas – diesel dual fuel engine at different load/speed conditions. The variation in the effect of natural gas fraction on engine performance with changing engine load was compared and analyzed. Nitrous oxide (N2O), nitrogen oxides (NOx), methane (CH4) and CO2 emissions were experimentally investigated and analyzed. The results revealed that the effect of natural gas fraction on engine performance changed with varying engine load and speed condition. N2O emissions from a dual fuel engine changed with increasing natural gas fraction, but the effect of N2O emissions on overall GHG emissions was not significant. However, CH4 emissions contributed significantly to the overall GHG emissions in a dual fuel engine, especially at low load conditions.
A Computational Investigation of Piston Bowl Geometry and Injector Spray Pattern Effects on Gasoline Compression Ignition in a Heavy-Duty Diesel Engine
Authors: Zhang Yu , Pei Yuanjiang , Tang Meng , Traver Michael 
Published: December 2019

Abstract
This study computationally investigates the potential of utilizing gasoline compression ignition (GCI) in a heavy-duty diesel engine to address a future ultra-low tailpipe NOx standard of 0.027 g/kWh while achieving high fuel efficiency.
By conducting closed-cycle, full-geometry, 3-D computational fluid dynamics (CFD) combustion simulations, the effects of piston bowl geometry, injector spray pattern, and swirl ratio (SR) were investigated for a market gasoline. The simulations were performed at 1375 rpm over a load range from 5 to 15 bar BMEP. The engine compression ratio (CR) was increased from 15.7 used in previous work to 16.5 for this study. Two piston bowl concepts were studied with Design 1 attained by simply scaling from the baseline 15.7 CR piston bowl, and Design 2 exploring a wider and shallower combustion chamber design.
The simulation results predicted that through a combination of the wider and shallower piston bowl design, a 14-hole injector spray pattern, and a swirl ratio of 1, Design 2 would lead to a 2–7% indicated specific fuel consumption (ISFC) improvement over the baseline by reducing the spray-wall interactions and lowering the in-cylinder heat transfer loss. Design 1 (10-hole and SR2) showed a more moderate ISFC reduction of 1–4% by increasing CR and the number of nozzle holes. The predicted fuel efficiency benefit of Design 2 was found to be more pronounced at low to medium loads.
Twin-Peak Heat Release Phenomenon Inside a Heavy-Duty Diesel Engine Retrofitted to Natural-Gas Spark Ignition
Authors: Liu Jinlong , Dumitrescu Cosmin E. , Ulishney Christopher 
Published: December 2019

Abstract
Existing compression ignition engines can be modified to spark ignition configuration to increase the use of natural gas in the heavy-duty transportation sector. A better understanding of the premixed natural gas combustion inside the original diesel chamber (i.e., flat-head-and-bowl-in-piston) will help improve the conversion process and therefore accelerate the diesel engine conversion. Previous studies indicated that the burning process in such engines is a two-stage combustion with a fast burning inside the bowl and a slower burning inside the squish. This paper used experimental and numerical results to investigate the combustion process at a more advanced spark timing representative of ultra-lean medium-load operation, which placed most of the combustion inside the compression stroke. At such operating conditions, the high turbulence intensity inside the squish region accelerated the flame propagation inside the squish region to the point that the burn inside the bowl separated less from that inside the squish region. However, several individual cycles produced a double-peak energy-release with the peak locations closer to the only one heat release peak seen in the average cycle. Moreover, RANS CFD simulations indicated that the time at which the flame entered the squish region was near the peak location of the energy-release process for the conditions investigated here. As a result, the data suggests that the double-peak seen in the apparent heat release rate was the result of the cycle-by-cycle variation in the flame propagation.
A Computational Investigation of the Impact of Multiple Injection Strategies on Combustion Efficiency in Diesel-Natural Gas Dual Fuel Low Temperature Combustion Engine
Authors: Bartolucci Lorenzo , Cordiner Stefano , Mulone Vincenzo , Krishnan Sundar R. , Srinivasan Kalyan K. 
Published: December 2019

Abstract
Dual fuel diesel-methane low temperature combustion (LTC) has been investigated by various research groups, showing high potential for emissions reduction (especially oxides of nitrogen (NOx) and particulate matter (PM)) without adversely affecting fuel conversion efficiency in comparison with conventional diesel combustion.
However, when operated at low load conditions, dual fuel LTC typically exhibit poor combustion efficiencies. This behavior is mainly due to low bulk gas temperatures under lean conditions, resulting in unacceptably high carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions. A feasible and rather innovative solution may be to split the pilot injection of liquid fuel into two injection pulses, with the second pilot injection supporting the methane combustion once the process is initiated by the first one.
In this work, diesel-methane dual fuel LTC is investigated numerically in a single-cylinder heavy-duty engine operating at 5 bar brake mean effective pressure (BMEP) at 85% and 75% percentage of energy substitution (PES) by methane (taken as a natural gas surrogate). A multidimensional model is first validated in comparison with experimental data obtained on the same single-cylinder engine for early single pilot diesel injection at 310 CAD and 500 bar rail pressure. With the single pilot injection case as baseline, the effects of multiple pilot injections and different rail pressures on combustion emissions are investigated, again showing good agreement with experimental data.
Apparent heat release rate and cylinder pressure histories as well as combustion efficiency trends are correctly captured by the numerical model. Results prove that higher rail pressures yield reductions of HC and CO by 90% and 75%, respectively, at the expense of NOx emissions, which increase by ∼30% from baseline. Furthermore, it is shown that post-injection during the expansion stroke does not support the stable development of the combustion front as the combustion process is confined close to the diesel spray core.
Analysis of a 5-Stroke Engine With a Two-Zone Equilibrium Combustion Products Model
Authors: Stuart Kurt , Yan Terry , Mathias James 
Published: December 2019

Abstract
A 5-stroke engine was analyzed using an improved 2-zone combustion model utilizing an equilibrium combustion model to calculate the gas properties in each zone. The flows of inlet, exhaust, and transfer port are handled using quasi-steady 1-D flow models. Heat transfer in the transfer port is also considered. The results are reported as indicated thermal efficiency and power output over a range of operating points and design characteristics, including engine RPM, compression ratio, overall expansion ratio, expansion cylinder clearance volume, and transfer port volume. It was found that the transfer port volume had a significant effect on the overall indicated thermal efficiency. The results were compared with those of a baseline 4-stroke engine. The 5-stroke engine with a compression ratio of 9:1, and an overall expansion ratio of 27:1 achieves a peak indicated thermal efficiency of 47%, representing a 6% increase over the baseline 4-stroke engine with the same compression ratio.
RCCI Investigations With n-Butanol and ULSD
Authors: Soloiu Valentin , Carapia Cesar E. , Wiley Justin T. , Moncada Jose , Gaubert Remi , Knowles Aliyah , Ilie Marcel , Rahman Mosfequr 
Published: December 2019

Abstract
The focus of this study is to reduce harmful NOx and soot emissions of a compression ignition (CI) engine using reactivity-controlled compression ignition (RCCI) with n-Butanol. RCCI was achieved with the port fuel injection (PFI) of a low reactivity fuel, n-butanol, and a direct injection (DI) of the highly reactive fuel ULSD #2 (Ultra Low Sulfur Diesel) into the combustion chamber. The reactivity, ID, and CD where determined using a Constant Volume Combustion Chamber (CVCC) where ID for n-butanol was found to be 15 times slower than ULSD. The emissions and combustion analysis was conducted at 1500 RPM at an experimental low engine load of 4 bar IMEP; the baseline for emissions comparison was conducted using conventional diesel combustion (CDC) with an injection timing of 16° BTDC at a rail pressure of 800 bar. RCCI was conducted utilizing 75% by mass PFI of n-butanol with 25% ULSD DI, showed a simultaneous reduction of both NOx and soot emissions at a rate of 96.2% and 98.7% respectively albeit with an increase in UHC emissions by a factor of 5. Ringing Intensity was also significantly reduced for Bu75ULSD25 (RCCI Experiment) with a reduction of 62.1% from CDC.
Characteristics of Diesel Spray With Varying Injection Rate
Authors: Naruemon Intarat , Liu Long , Liu Dai , Ma Xiuzhen 
Published: December 2019

Abstract
Multiple-injection is an effective injection strategy in order to control the advanced combustion processes in diesel engines. However, because of the multiple-injection application, cause the duration of each injection is shortened, such as the pilot injection and post-injection. The short injection duration results in a very short quasi-steady injection process so that the ramping-up and ramping-down injection processes occupied a much larger scale during the injection. As a result, this circumstance of the spray evolution not been fully understood. To investigate the diesel spray propagation with varying injection rate, visual experiments and numerical simulation analyses on diesel spray were performed. The penetrations of diesel sprays with short injection duration were obtained by reflected shadowgraphy in a combustion chamber’s constant-volume with the multi-hole injector. The diesel spray with varying injection rates was modeled by using CONVERGE CFD software and the model was calibrated and validated by the experimental data. Then diagnosed the spray characteristics including spray penetration, Sauter means diameter, as well as fuel concentration distribution, were analyzed with different injection quantities and injection rate shapes. The spray mixing analysis included that after the end-of-injection in order to consider the low-temperature combustion phenomenon. The shape of the improved injection rate in the fuel mixture considered in the case of injection ending before or after the ignition time was summarized for different conditions.
Effect of Ambient Pressure on the Behavior of Single-Component Fuels in a Gasoline Multi-Hole Injector
Authors: Nocivelli Lorenzo , Yan Junhao , Saha Kaushik , Magnotti Gina M. , Lee Chia-Fon , Som Sibendu 
Published: December 2019

Abstract
The injection characteristics of neat ethanol and pure iso-octane are studied under different ambient pressure and temperature conditions. Injection under flash-boiling conditions can enhance liquid atomization and evaporation, providing the possibility of improvement in the fuel/air mixing. These super-heated conditions often introduce phenomena that are not taken into account in the standard modeling of sprays for engine applications. The present work proposes a numerical investigation of the behavior of Engine Combustion Network’s 8-hole spray-G injector, starting at the subcooled nominal condition and reducing the ambient pressure at constant low temperature to reach the flare flash-boiling condition. To initialize the properties of the injected fuel, the flow in the nozzle is simulated with a Eulerian approach, handling the two phases with a mixture model and the phase change, due to cavitation and flash boiling, with the Homogenous Relaxation Model. A map of the mixture’s kinematic and thermal behavior is obtained at the interface between the injector and the chamber to initialize the Lagrangian simulations. A literature-based vaporization model is implemented to obtain the proper description of the characteristic features of a multi-hole spray under super-heated conditions, like plume-plume interaction. The numerical representation of the spray is validated in terms of penetration and radial spreading on DBI images, reproducing the light attenuation profiles caused by the presence of the liquid spray. Simulations show that coupled nozzle flow and spray calculations capture the spray morphology and shape better compared to calculations performed without considering the nozzle flow simulation details, especially under flare flash conditions.
Design of Passive Two-Phase Thermosyphons for Server Cooling
Authors: Amalfi Raffaele L. , Marcinichen Jackson B. , Thome John R. , Cataldo Filippo 
Published: December 2019

Abstract
The main objective of this paper is to utilize an improved version of the simulator presented at InterPACK 2017 to design a thermosyphon system for energy-efficient heat removal from 2-U servers used in high-power datacenters. Currently, between 25% and 45% of the total energy consumption of a datacenter (this number does not include the energy required to drive the fans at the server-level) is dedicated to cooling, and with a predicted annual growth rate of about 15% (or higher) coupled with the plan of building numerous new datacenters to handle the “big data” storage and processing demands of emerging 5G networks, artificial intelligence, electrical vehicles, etc., the development of novel, high efficiency cooling technologies becomes extremely important for curbing the use of energy in datacenters.
Notably, going from air cooling to two-phase cooling, not only enables the possibility to handle the ever higher heat fluxes and heat loads of new servers, but it also provides an energy-efficient solution to be implemented for all servers of a datacenter to reduce the total energy consumption of the entire cooling system. In that light, a pseudo-chip with a footprint area of 4 × 4 cm2 and a maximum power dissipation of 300 W (corresponding heat flux of about 19 W/cm2), will be assumed as a target design for our novel thermosyphon-based cooling system. The simulator will be first validated against an independent database and then used to find the optimal design of the chip’s thermosyphon. The results demonstrate the capability of this simulator to model all of the thermosyphon’s components (evaporator, condenser, riser and downcomer) together with overall thermal performance and creation of operational maps. Additionally, the simulator is used here to design two types of passive two-phase systems, an air- and a liquid-cooled thermosyphon, which will be compared in terms of thermal-hydraulic performance. Finally, the simulator will be used to perform a sensitivity analysis on the secondary coolant side conditions (inlet temperature and mass flow rate) to evaluate their effect on the system performance.
Thermal Analysis of 3D ICs With TSVs Placement Optimization
Authors: Ren Zongqing , Alqahtani Ayed , Bagherzadeh Nader , Lee Jaeho 
Published: December 2019

Abstract
While 3D integrated circuits (3D ICs) offer a great enhancement in performance, the increased power density, nonuniform power distribution and high thermal resistance pose significant thermal management challenges. Thermal through-silicon-vias (TTSVs) are TSVs that do not carry signal but facilitate heat transfer across stacked dies. The use of TTSVs occupies extra space and extends the distance between IC blocks leading to an increase in signal delay. The trade-offs between the temperature and wirelength are evident in the TTSV placement. In this paper, we propose a hierarchical approach to optimize the floorplan of a 3D Nehalem-based multicore processor. The floorplan of a single core is optimized using simulated annealing (SA)-based algorithm and the floorplan of the entire 3D IC is generated based on the symmetric operation. Our simulation results show that the peak temperature decreases with the TTSV area overhead and the wirelength strongly depends on the TTSV placement. Compared to the SA-optimized floorplan with no TTSVs, the SA-optimized floorplans with TTSV offer 6–15 °C more reduction in peak temperature while keeping the wirelength increase from 10 % to 40 % at 2–20 % TTSV area overheads. We also evaluate the effects of anisotropic thermal transport in TTSVs and show that the lateral thermal conductivity of TTSV has a significant impact on the peak temperature of 3D ICs.
Effects of Cooling Architecture and PCB Layout Co-Design on the Concurrent Thermal and Electrical Performance of an On-Board Electric Vehicle Charger
Authors: Tayyara Omri , Gupta Kshitij , Da Silva Carlos , Nasr Miad , Assadi Amir , Trescases Olivier , Amon Cristina H. 
Published: December 2019

Abstract
Significant advances are needed to optimize the charging speed, reliability, safety, and cost of today’s conservatively designed electric vehicle charging systems. The design and optimization of these novel engineering systems require concurrent consideration of thermal and electrical phenomena, as well as component- and system-level dynamics and control to guarantee reliable continuous operation, scalability, and minimum footprint. This work addresses the concurrent thermal and electrical design constraints in a high-density, on-board, bi-directional charger (referred to as power-hub) with vehicle-to-grid (V2G), grid-to-vehicle (G2V), vehicle-to-house (V2H) and vehicle-to-vehicle (V2V) power transfer capabilities. The electrical design of this charger consists of dc-dc and dc-ac power stages connected in series. The power-stage circuits are implemented on a Printed Circuit Board (PCB) with 16 surface-mount Silicon Carbide (SiC) MOSFETs, three inductors and one transformer. The main goal of this work is to investigate the interplay between the cooling architecture and the PCB layout, and the corresponding impact on the heat dissipation and parasitic inductance. This work compares the performance of three prototypes of this multifunctional charger using multi-physics simulations and experimental tests.