scholarly journals Methodology improvements to simulate performance and emissions of engine transient cycles from stationary operating modes: A case study applied to biofuels

Fuel ◽  
2022 ◽  
Vol 312 ◽  
pp. 122977
Author(s):  
Fernando Cruz-Peragón ◽  
Eloísa Torres-Jiménez ◽  
Luka Lešnik ◽  
Octavio Armas
Keyword(s):  
Operating Modes ◽  
Performance And Emissions

scholarly journals Optimization of Energy-Efficient Speed Profile for Electrified Vehicles

2018 ◽  
Author(s):  
Hadi Abbas ◽  
Youngki Kim ◽  
Jason B. Siegel ◽  
Denise M. Rizzo
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Minimum Energy ◽  
Efficient Operation ◽  
Operating Modes ◽  
Minimum Energy Consumption ◽  
System A ◽  
Trip Time ◽  
Route Information

This paper presents a study of energy-efficient operation of vehicles with electrified powertrains leveraging route information, such as road grades, to adjust the speed trajectory. First, Pontryagin’s Maximum Principle (PMP) is applied to derive necessary conditions and to determine the possible operating modes. The analysis shows that only 5 modes are required to achieve minimum energy consumption; full propulsion, cruising, coasting, full regeneration, and full regeneration with conventional braking. The minimum energy consumption problem is reformulated and solved in the distance domain using Dynamic Programming to optimize speed profiles. A case study is shown for a light weight military robot including road grades. For this system, a tradeoff between energy consumption and trip time was found. The optimal cycle uses 20% less energy for the same trip duration, or could reduce the travel time by 14% with the same energy consumption compared to the baseline operation.

scholarly journals Homogenization Effects of Variable Speed Limits

2014 ◽  
Vol 15 (2) ◽  
pp. 130-143 ◽  
Author(s):  
Alvaro Garcia-Castro ◽  
Andres Monzon
Keyword(s):  
Weather Conditions ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Speed Limits ◽  
Key Indicator ◽  
Variable Speed Limits ◽  
Performance And Emissions ◽  
Speed Management ◽  
Road Performance

Abstract Changing factors (mainly traffic intensity and weather conditions) affecting road conditions require a suitable optimal speed at any time. To solve this problem, variable speed limit systems (VSL) - as opposed to fixed limits - have been developed in recent decades. This term has included a number of speed management systems, most notably dynamic speed limits (DSL). In order to avoid the indiscriminate use of both terms in the literature, this paper proposes a simple classification and offers a review of some experiences, how their effects are evaluated and their results This study also presents a key indicator which measures the speed homogeneity and a methodology to obtain the data based on floating cars and GPS technology applying it to a case study on a section of the M30 urban motorway in Madrid (Spain). It also presents the relation between this indicator and road performance and emissions values.

Improving the performance of a diesel engine by changing injectors characteristics after reduction on the compression ratio

2021 ◽  
Vol 15 (2) ◽  
pp. 8153-8168
Author(s):  
Saeed Chamehsara ◽  
Mohammadreza Karami
Keyword(s):  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Engine Performance ◽  
Combustion Engines ◽  
Fuel Injector ◽  
Start Time ◽  
Performance And Emissions ◽  
Nozzle Hole ◽  
The Impact

In order to repair internal combustion engines, sometimes it is necessary to replace the components of these engines with each other. Therefore changes in engine performance are inevitable in these conditions. In the present study, by changing the coneccting rod and the crank of the OM457 turbo diesel-fueled engine with the OM444, it was observed that the performance of the engine decreases. Numerical simulations have been carried out to study the Possible ways to mitigate this reduction. One way to achieve this goal is to change the fuel injector’s characteristics such as, fuel injector’s nozzle hole diameter, number of nozzle holes, and start time of fuel injection. In this study, the impact of these parameters on the performance and emissions of these engines were analyzed. Another scenario is an increase in inlet fuel and air by the same amount. The results indicate that By reducing the diameter of fuel injector holes and hole numbers, the performance of the engine was increased. on the other hand, the NOx emissions were increased while the amount of soot emission decreased. The same results were concluded by retarding the start time of injection. Subsequently, a case study of changing fuel injector parameters for mitigation of decreased performance was performed. These parameters were simultaneously applied, and results were compared. The performance of the engine with improved injector’s characteristics was close to the main OM457. Similar results were obtained by increasing the amount of inlet air and fuel.

Automated Modeling and Mode Screening for Exhaustive Search of Double-Planetary-Gear Power Split Hybrid Powertrains

2014 ◽  
Author(s):  
Xiaowu Zhang ◽  
Huei Peng ◽  
Jing Sun ◽  
Shengbo Li
Keyword(s):  
Planetary Gear ◽  
General Motors ◽  
Screening Process ◽  
Automated Modeling ◽  
Operating Modes ◽  
Hybrid Powertrains ◽  
Power Split ◽  
Model Year ◽  
Operation Flexibility

Double Planetary Gear (PG) power-split hybrid powertrains have been used in production vehicles from Toyota and General Motors. Some of the designs use clutches to achieve multiple operating modes to improve powertrain operation flexibility and efficiency at the expense of higher complexity. In this paper, an automatic modeling and screening process is developed, which enables exhaustively search through all designs with different configurations, clutch locations and operating modes. A case study was conducted based on the configuration used in the model year 2010 Prius and Camry hybrids. It was found that by adding clutches, fuel economy can be improved significantly for plug-in hybrid (charge depletion) operations.

scholarly journals HVAC Operation Schemes and Commissioning Process Resolving Stack Effect Problem and Adjusting According to Changes in the Environment: A Case Study in High-Rise Building in South Korea

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2299
Author(s):  
Jungyeon Yu ◽  
Angie Kim ◽  
Sanghwan Bae ◽  
Dongwoo Cho ◽  
Kee Han Kim
Keyword(s):  
South Korea ◽  
Noise Level ◽  
Operation Mode ◽  
Hvac System ◽  
Commercial Building ◽  
Stack Effect ◽  
Operating Modes ◽  
High Rise ◽  
High Rise Building

Various problems often arise in high-rise buildings during the winter months due to the stack effect. In this study, the high-rise building of interest, located in South Korea, was experiencing constant loud noises in the winter due to the stack effect. Thus, we created a noise level reduction plan by creating a method for pressurizing the high-rise zones of the building according to outdoor conditions. To discover the appropriate pressurization operating modes, we applied a two-year commissioning process to the 50-story building of interest. The 1st- and 47th-floor elevator halls were identified to have the highest noise levels of all other floors. Prior to applying the reduction plan, the maximum noise level on the first floor with the HVAC system turned off was 85 dB(A) and with the HVAC system turned on it was 70 dB(A). Both values exceeded the criteria of 57 dB(A) for a lobby space of a commercial building. In the case of the 47th floor, the maximum noise level with the HVAC system turned off was 58.7 dB(A) and with the HVAC system turned off was 56.0 dB(A), despite the latter having increased airtightness performance and applying preliminary pressurization (i.e., HVAC operation mode 2). These values exceeded the criteria of 48 dB(A) for an elevator hall in a commercial building. Following this initial data, we determined to pressurize the high/mid-rise zones of the building according to the outdoor air temperature and wind velocity conditions, which we categorized into four types (i.e., HVAC operation mode 4). To this effect, the first-floor elevator hall’s maximum noise level was 56.6 dB(A), meeting the criteria, and the 47th-floor elevator hall’s maximum noise level was 49.5 dB(A), still exceeding the criteria but by an insignificant amount. Although the HVAC pressurization operation we utilized resulted in favorable results for the target building A, it may not be as effective in other new high-rise buildings, creating changes to the indoor air environment or to the energy costs in maintaining a building. However, for the purposes of resolving the stack effect, we believe that the commissioning process we took to optimize the HVAC operation that is presented here can be applied to other new and existing high-rise commercial buildings.

scholarly journals Characteristic groundwater level regimes in the capture zones of radial collector wells and importance of identification (Case study of Belgrade Groundwater Source)

2016 ◽  
pp. 43-53 ◽  
Author(s):  
Djordjije Bozovic ◽  
Dusan Polomcic ◽  
Dragoljub Bajic
Keyword(s):  
Groundwater Level ◽  
Background Information ◽  
Preliminary Assessment ◽  
Groundwater Levels ◽  
Operating Modes ◽  
Capture Zones ◽  
Level Regime ◽  
Groundwater Source ◽  
Discharge Capacities

Assessment of the operating modes of radial collector wells reveals that the pumping levels in the well caissons are very low relative to the depth/elevation of the laterals, which is a common occurrence at Belgrade Groundwater Source. As a result, well discharge capacities vary over a broad range and groundwater levels in the capture zones differ even when the rate of discharge is the same. Five characteristic groundwater level regimes are identified and their origin is analyzed using representative wells as examples. The scope and type of background information needed to identify the groundwater level regime are presented and an interpretation approach is proposed for preliminary assessment of the aquifer potential at the well site for providing the needed amount of groundwater.

The Genesis and Internal Dynamics of El Salvador's People's Revolutionary Army, 1970–1976

2014 ◽  
Vol 38 (01) ◽  
pp. 102-129
Author(s):  
ALBERTO MARTÍN ÁLVAREZ ◽  
EUDALD CORTINA ORERO
Keyword(s):  
Latin America ◽  
El Salvador ◽  
Early Years ◽  
Left Wing ◽  
Internal Dynamics ◽  
Internal Coherence ◽  
The 1960S

AbstractUsing interviews with former militants and previously unpublished documents, this article traces the genesis and internal dynamics of the Ejército Revolucionario del Pueblo (People's Revolutionary Army, ERP) in El Salvador during the early years of its existence (1970–6). This period was marked by the inability of the ERP to maintain internal coherence or any consensus on revolutionary strategy, which led to a series of splits and internal fights over control of the organisation. The evidence marshalled in this case study sheds new light on the origins of the armed Salvadorean Left and thus contributes to a wider understanding of the processes of formation and internal dynamics of armed left-wing groups that emerged from the 1960s onwards in Latin America.

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