Active Air Control System to Reduce Two-Stroke Cycle Engine Pollutant Emissions: Validation and Laboratory Testing

2009 ◽  
Author(s):  
Diana K. Grauer ◽  
Kirby S. Chapman
Keyword(s):  
Control System ◽  
Flow Rate ◽  
Equivalence Ratio ◽  
Flow Model ◽  
Air Flow ◽  
Pollutant Emissions ◽  
Cylinder Flow ◽  
Air Control ◽  
Scavenging Efficiency ◽  
Stroke Cycle

This paper presents results from Phase 2 of the development of an Active Air Control (AAC) system to balance air flow into each cylinder of a turbocharged engine system, a PRCI-funded emissions reduction project. Imbalance in air flow creates a discontinuity in trapped equivalence ratio from cylinder to cylinder. Trapped equivalence ratio is directly proportional to NOX production and a function of the fuel flow rate, air flow rate, and, in a two-stroke cycle engine, the scavenging efficiency. Only when these three characteristics are balanced cylinder to cylinder will the combustion and the NOX production in each cylinder be equal. The engine NOX production will be disproportionately high if even one cylinder operates less lean relative to the other cylinders. This paper reports on the testing of an AAC system on a two-cylinder air flow bench at the National Gas Machinery Laboratory at Kansas State University. The results from these tests were then used to further validate the comprehensive, variable geometry, multi-cylinder flow model referred to as the Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS). CAIMENS is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle-resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has been validated with data from the NGML multi-cylinder flow bench. This information has allowed the research team to (1) quantify the impact of air flow imbalance and (2) provide detailed information leading to the specification of the active air flow control system. The end point of this project is an AAC system that can, with some engineering effort, be applied to field engines.

scholarly journals Air flow model development and application in a complex combined sewer system

2020 ◽  
Vol 82 (8) ◽  
pp. 1687-1700 ◽  
Author(s):  
Hasan Zobeyer ◽  
David Z. Zhu ◽  
Stephen Edwini-Bonsu
Keyword(s):  
Flow Rate ◽  
Flow Model ◽  
Air Flow ◽  
Model Development ◽  
Iterative Solution ◽  
Momentum Equation ◽  
Air Flow Rate ◽  
Sewer System ◽  
Combined Sewer ◽  
Combined Sewer System

Abstract A steady-state air flow model was developed and applied in a complex combined sewer system in the city of Edmonton, Alberta, Canada. The model solves the continuity at each junction and the momentum equation for the links coupled with dropshaft and other manholes. The dropshaft pressure gradient is computed using the dropshaft equation and air flow rate through manhole pickholes is computed considering the opening as an orifice. A leakage factor is used as a calibration parameter to represent the area through which air can leak from the manholes into the neighborhood. The model uses an iterative solution algorithm with a forward sweep for the continuity and backward sweep for the momentum equation. An underrelaxation is applied to update pressure in each iteration for model stability. The model was calibrated and validated by using the measured air flow rate and manhole pressure in the sewer network, with good results. An analysis of the air flow characteristics shows that a significant amount of air is brought into the system due to a large headspace in the upstream trunk but over 70% of this air is released into the neighborhood due to reduced headspace in the downstream trunk.

The Influence of Film Cooling on Emissions for a Low NOx Radial Swirler Gas Turbine Combustor

2001 ◽  
Author(s):  
G. E. Andrews ◽  
M. N. Kim
Keyword(s):  
Mach Number ◽  
Gas Turbine ◽  
Flow Rate ◽  
Film Cooling ◽  
Equivalence Ratio ◽  
Air Flow ◽  
Gas Turbine Combustor ◽  
Cooling Flow ◽  
Full Coverage ◽  
Primary Zone

An experimental investigation was undertaken of the influence on emissions of full coverage discrete hole film cooling of a lean low NOx radial swirler natural gas combustor. The combustor used radial swirler vane passage fuel injection on the centre of the vane passage inlet. The test configuration was similar to that used in the Alstom Power Tornado and related family of low NOx gas turbines. The test conditions were simulated at atmospheric pressure at the flow condition of lean low NOx gas turbine primary zones. The tests were carried out at an isothermal flow Mach number of 0.03, which represents 60% of industrial gas turbine combustor airflow through the swirl primary zone. The effusion film cooling used was Rolls-Royce Transply, which has efficient internal cooling of the wall as well as full coverage discrete hole film cooling. Film cooling levels of 0, 16 and 40% of the primary zone airflow were investigated for a fixed total primary zone air flow and reference Mach number of 0.03. The results showed that there was a major increase in the NOx emissions for 740K inlet temperature and 0.45 overall equivalence ratio from 6ppm at zero film cooling air flow to 32ppm at 40% coolant flow rate. CO emissions increased from 25ppm to 75ppm for the same increase in film cooling flow rate. It was shown that the main effect was the creation of a richer inner swirler combustion with a surrounding film cooling flow that did not mix well with the central swirling combustion. The increase in NOx and CO could be predicted on the basis of the central swirl flow equivalence ratio.

Improving the estimation of methodological errors in reproducing the volumetric air flow rate by reference critical nozzle

Metrologiya ◽  
2021 ◽  
pp. 4-30
Author(s):  
V. I. Chesnokov
Keyword(s):  
Kinetic Energy ◽  
Flow Rate ◽  
Gas Flow ◽  
Flow Model ◽  
Air Flow ◽  
Operating Conditions ◽  
Initial Kinetic Energy ◽  
Methodological Error ◽  
Air Flow Rate ◽  
Critical Nozzle

In the development of the previously obtained results a more accurate estimate of the methodological error in reproducing the volumetric air flow rate by reference critical nozzle is given, associated with the choice of the gas flow model and due to taking into account the initial kinetic energy of the flow at the nozzle inlet. Based on improved flow model an analytical evaluation of the methodological error in reproducing the volumetric air flow rate by reference critical nozzle, which is due to a change in the humidity of the working air, has been carried out. It is shown that the methodological error in reproducing the volumetric air flow rate by reference critical nozzle, associated with a change in the air humidity, as well as the analogies methodical error caused by the existence of the initial kinetic energy of the flow, must be taken part in accuracy characteristics at the real operating conditions of the standard volumetric air flow rate using critical nozzles.

A Computer-Based Air Flow Control System for Aerosol and Filtration Research

2015 ◽  
Vol 771 ◽  
pp. 137-140 ◽  
Author(s):  
Muhammad Miftahul Munir ◽  
Muhammad Sainal Abidin ◽  
Abdul Rajak ◽  
Khairurrijal
Keyword(s):  
Control System ◽  
Flow Control ◽  
Flow Rate ◽  
Pulse Width Modulation ◽  
Air Flow ◽  
Flow Sensor ◽  
Air Filtration ◽  
Air Filter ◽  
Flow Control System ◽  
Air Flow Control

An airflow control system is one of important parts in the scanning mobility particle sizers system (SMPS) used in the field of aerosol and air filtration. In this paper, the air flow control system that consists of an air filter, a blower, an air flow sensor, a controller, and a computer are reported. A flow rate adjustment was performed by varying the rotation speed of the blower using a pulse width modulation (PWM) technique. The air flow sensor capable of measuring flow rate up to 20 liters / min was used to measure the air flow rate. In order to keep at a certain value of the flow rate, a proportional-integral-derivative (PID) control action was employed in which PID controller were manually tune. The results showed that the desired value of flow rate was quickly achieved with little overshoot was observed in the system output.

scholarly journals Air Flow Model for Mixed-Mode and Indirect-Mode Natural Convection Solar Drying of Maize

2020 ◽  
Vol 10 (2) ◽  
pp. 1
Author(s):  
Isaac N. Simate
Keyword(s):  
Natural Convection ◽  
Flow Rate ◽  
Mixed Mode ◽  
Flow Model ◽  
Air Flow ◽  
Solar Drying ◽  
Air Flow Rate ◽  
Thermal Buoyancy ◽  
Early Stages ◽  
Grain Moisture

An air flow model for mixed-mode and indirect-mode natural convection solar drying of maize to help understand the factors that influence air flow in the dryer is presented. Temperatures at various sections of the dryer obtained from drying experiments were input to the air flow model to predict the respective thermal buoyancies. The air flow rate was determined by balancing the sum of the buoyancy pressures with the sum of the flow resistances in the various sections of the dryer. To validate the model, the predicted air flow was compared with measured air flow from experiments. For both the mixed-mode and indirect-mode, the biggest driver of the air flow is the thermal buoyancy created in the collector, while the grain bed is the dominant pressure drop. Thermal buoyancy on top of the grain bed is largely responsible for the variation in air flow, translating into low mass air flow during the early stages of drying when grain moisture is high, and higher air flow in the later stages when grain moisture is low. The heating of the grain bed by direct radiation in the mixed-mode translates into a slightly higher air flow rate than the indirect-mode. The implications are that a thinner grain bed results in shorter drying time as it has a higher air flow rate than a thicker one. To mitigate the low air flow at the early stages of drying, the collector length should be appropriately designed for a desired air flow.

Coordinated Control of Fuel Cell Air Supply System Using Model Predictive Control

2010 ◽  
Author(s):  
Lie Tang ◽  
Robert G. Landers
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Nonlinear Model ◽  
Flow Rate ◽  
Air Flow ◽  
Pressure Control ◽  
Cathode Side ◽  
Model Predictive Controller ◽  
Air Supply ◽  
Predictive Controller

Oxidant (air flow) control is an important aspect of fuel cell reactant control system which is designed to fulfill two purposes: air flow rate control and pressure control. These tasks require coordinated valve operation to reduce pressure variation and stabilize flow rate. In this paper, a nonlinear model describing filling dynamics of the supply and return manifolds is presented. The nonlinear model is then linearized around the stack operating point, based on which a model predictive controller is designed to maintain a constant supply and manifold pressures, as well as a constant pressure on the cathode side. Simulation studies demonstrate the model predictive controller is capable of not only regulating constant pressures during steady state operation, but also substantially reducing pressure variations during transient periods. Simulation also indicates that the control system has good robustness against model uncertainty.

The Development of a Monitoring and Control System for Pulverised Coal Flames Using Neural Networks

2003 ◽  
Author(s):  
O. H. Tan ◽  
S. J. Wilcox ◽  
J. Ward ◽  
M. Lewitt
Keyword(s):  
Control System ◽  
Low Cost ◽  
Air Flow ◽  
Combustion Process ◽  
Combustion Noise ◽  
Pollutant Emissions ◽  
Furnace Chamber ◽  
Gaseous Emissions ◽  
Monitoring And Control ◽  
Secondary Air

This paper presents the results obtained from a series of experiments that have been conducted on a 150kW pf burner rig based at Casella CRE Ltd. in the United Kingdom. These experiments systematically varied the burner swirl number and the secondary air flow rate over a significant range for two different coals so that both satisfactory and ‘poor’ combustion conditions were obtained. The infra-red emissions from the flame and the combustion noise generated in the furnace chamber were measured with appropriate sensors as were the fuel and air flow rates and pollutant emissions. The signals from the sensors were analysed using signal processing techniques to yield a number of features. These in turn were employed to train a neural network to accurately estimate the gaseous emissions from the rig, such as NOx and CO. In a separate set of experiments, where the combustion process was placed in a poor condition, the sensors were coupled with the neural models and incorporated into an intelligent control system, which was able to alter the excess air level to improve the process. In this fashion simultaneous low Nox and CO levels were achieved with both coal types. This method thus uses a combination of relatively low cost sensors and artificial intelligence techniques to control the combustion of the pulverised fuel burner. It is envisaged as particularly attractive for multiple burner installations that are fed from a common manifold, where individual burner performance is not known.

HIGH-SPEED IMAGING FOR AN OPTICALLY ACCESSIBLE ROTATING DETONATION ENGINE

2020 ◽  
Author(s):  
Yuhui Wang ◽  
◽  
Jialing Le ◽  
Keyword(s):  
Low Temperature ◽  
Flow Rate ◽  
High Speed ◽  
Equivalence Ratio ◽  
Air Flow ◽  
Detonation Waves ◽  
Outer Diameter ◽  
Air Flow Rate ◽  
High Speed Imaging ◽  
Rotating Detonation

Nonpremixed rotating detonation waves (RDWs) for ethylene or hydrogen and air sources at room temperatures 283-284 K were obtained in the same hollow combustor. The combustor was optically accessible by embedded a piece of quartz glass in the combustor wall. The hollow combustor channel here had an outer diameter 100 mm. Fuel and air were injected into the combustor from 150 cylindrical orifices of a diameter 0.8 mm axially and a circular channel with a width 1 mm radially, respectively. The detonation speeds for ethylene and air were 1562 or 1389 m/s for the air flow rate 642.35 g/s at an equivalence ratio 0.78. The detonation speed for hydrogen and air were 2013 m/s for the air flow rate 327.73 g/s at an equivalence ratio 1.24. Hydrogen operation was more stable than ethylene operation in the condition of low temperature gas sources. High-speed images showed RDW structures were changeful and unstable. Low-temperature regions could intrude into and break the detonation wave.

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