Adaptive Prediction of Transient Air Fuel Ratio Based on Forgetting Factor Algorithm for a Coal-Bed Gas Engine

2011 ◽  
Vol 130-134 ◽  
pp. 814-819
Author(s):  
Qin Teng ◽  
Xiang Gong ◽  
Peng An
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Coal Bed ◽  
Forgetting Factor ◽  
Fuel Gas ◽  
Flow Rates ◽  
Gas Engine ◽  
Adaptive Models

In order to solve the problems of pumping fluctuations and bandwidth limitation to dynamic air fuel ratio (AFR) control for a coal-bed gas engine, adaptive models for air mass flow rate and fuel gas mass flow rate in intake system and exhaust AFR were constructed by a recursive identification method based on the forgetting factor (FF) algorithm. A linear time-varying equation error model was selected as the structure of the adaptive models. Firstly, the throttle position and crankshaft speed signals were used to predict the air and fuel gas flow rates. Secondly, the AFR was predicted in real time according to the estimated air and fuel gas flow rates. The trade-off between tracking ability and noise sensitivity was realized by adjusting a FF. The experiment validations at transient operating conditions of the engine accelerating and decelerating show that, adaptive recursive models of the air and gas flow rates with a larger FF can not only track the averaging values of the flow rates, but also deal with the phase delays introduced by the filter, the AFR adaptive recursive model with a smaller FF can predict transient AFR accurately.

An Experimental Study of the Flow of R-407C in an Adiabatic Spiral Capillary Tube

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
M. K. Mittal ◽  
R. Kumar ◽  
A. Gupta
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Flow Rates ◽  
Tube Test ◽  
Mass Flow Rates ◽  
R 134A

The objective of this study is to investigate the effect of coiling on the flow characteristics of R-407C in an adiabatic spiral capillary tube. The characteristic coiling parameter for a spiral capillary tube is the coil pitch; hence, the effect of the coil pitch on the mass flow rate of R-407C was studied on several capillary tube test sections. It was observed that the coiling of the capillary tube significantly reduced the mass flow rate of R-407C in the adiabatic spiral capillary tube. In order to quantify the effect of coiling, the experiments were also conducted for straight a capillary tube, and it was observed that the coiling of the capillary tube reduced the mass flow rate in the spiral tube in the range of 9–18% as compared with that in the straight capillary tube. A generalized nondimensional correlation for the prediction of the mass flow rates of various refrigerants was developed for the straight capillary tube on the basis of the experimental data of R-407C of the present study, and the data of R-134a, R-22, and R-410A measured by other researchers. Additionally, a refrigerant-specific correlation for the spiral capillary was also proposed on the basis of the experimental data of R-407C of the present study.

Identification of Wake Convection and Flow Outline in the Interface Region of Blade Rows With Axial Gap in a Counter Rotating Turbine

2019 ◽  
Author(s):  
Rayapati Subbarao ◽  
M. Govardhan
Keyword(s):  
Flow Pattern ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Three Dimensional ◽  
Interface Region ◽  
Turbine Stage ◽  
Deviation Angle ◽  
Flow Rates ◽  
Improved Performance

Abstract In a Counter Rotating Turbine (CRT), the stationary nozzle is trailed by two rotors that rotate in the opposite direction to each other. Flow in a CRT stage is multifaceted and more three dimensional, especially, in the gap between nozzle and rotor 1 as well as rotor 1 and rotor 2. By varying this gap between the blade rows, the flow and wake pattern can be changed favorably and may lead to improved performance. Present work analyzes the aspect of change in flow field through the interface, especially the wake pattern and deviation in flow with change in spacing. The components of turbine stage are modeled for different gaps between the components using ANSYS® ICEM CFD 14.0. Normalized flow rates ranging from 0.091 to 0.137 are used. The 15, 30, 50 and 70% of the average axial chords are taken as axial gaps in the present analysis. CFX 14.0 is used for simulation. At nozzle inlet, stagnation pressure boundary condition is used. At the turbine stage or rotor 2 outlet, mass flow rate is specified. Pressure distribution contours at the outlets of the blade rows describe the flow pattern clearly in the interface region. Wake strength at nozzle outlet is more for the lowest gap. At rotor 1 outlet, it is less for x/a = 0.3 and increases with gap. Incidence angles at the inlets of rotors are less for the smaller gaps. Deviation angle at the outlet of rotor 1 is also considered, as rotor 1-rotor 2 interaction is more significant in CRT. Deviation angle at rotor 1 outlet is minimum for this gap. Also, for the intermediate mass flow rate of 0.108, x/a = 0.3 is giving more stage performance. This suggests that at certain axial gap, there is better wake convection and flow outline, when compared to other gap cases. Further, it is identified that for the axial gap of x/a = 0.3 and the mean mass flow rate of 0.108, the performance of CRT is maximum. It is clear that the flow pattern at the interface is changing the incidence and deviation with change in axial gap and flow rate. This study is useful for the gas turbine community to identify the flow rates and gaps at which any CRT stage would perform better.

The Theoretical and Experimental Evaluation of Gas-Particle Flow in Laser Cladding Repairing of Three Dimensions

Materials ◽  
2004 ◽  
Author(s):  
Hui-Shan Li ◽  
Xi-Chen Yang ◽  
Chun-Xian Wang
Keyword(s):  
Mass Flow Rate ◽  
Laser Cladding ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Ccd Camera ◽  
Longitudinal Axis ◽  
Three Dimensions ◽  
Theoretical Evaluation ◽  
Transportation Equipment

In this paper, the powders transportation in laser cladding repairing during the coaxial powder-feeding was evaluated. The theoretical evaluation is based on a two-fluid approach in which both the gas and particulate phase is treated each phase separately, and the only link between the phases is through the drag force in the momentum equations. The particles velocities are calculated with changes of the gas flow and mass flow rate. This is important for the coaxial nozzle and the carrier-gas powder transportation equipment characteristics determined. An experimentally of the influence of carrying gas on the powder stream was set up. The gas-particles flowing from the nozzle was illuminated by a 2D sheet of light. A typical image from the CCD camera is captured. The axial velocity and cross section were described. According to the results, it was found that: (1) Different mass flow rate Mp=0.5g/s, 0.67g/s, 0.83g/s, 1g/s, the powder stream luminance intensity and distribution will change. (2) The distribution of powder concentration at longitudinal axis from the nozzle exit is shown. The faster particulates stream has the less density per unit volume for a given mass flow rate. (3) The gas velocity for transportation is the most important parameter.

An analytical and experimental investigation of the velocities of particles entrained by the gas flow in nozzles

1968 ◽  
Vol 33 (1) ◽  
pp. 131-149 ◽  
Author(s):  
John H. Neilson ◽  
Alastair Gilchrist
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Particle Velocity ◽  
Flow Rate ◽  
Relative Velocity ◽  
Gas Flow ◽  
Wall Surface ◽  
Erosion Damage ◽  
Limiting Value

Among the parameters which determine the erosion damage sustained by the walls of a nozzle, in which a mixture of gas and particles is flowing is the speed attained by the particle before collision with the wall surface. This work is concerned with the determination of the particle velocity, and a number of relationships are given from which the variation in particle velocity can be obtained for a variety of gas conditions. The changes of state and velocity of the gas, occasioned by the interchange of heat and work between the gas and the particles are dependent on the ratio of the mass flow rate of particles to the mass flow rate of gas. It is shown that if this ratio is small the particle velocity may be obtained without serious error by assuming that the gas conditions are not affected by the presence of particles. Figures for the limiting value of this ratio for certain flows are given. The effects of particle size, density and initial relative velocity are investigated analytically and experimentally.

Permeability and Inertial Coefficients of Porous Media for Air Bearing Feeding Systems

2007 ◽  
Vol 129 (4) ◽  
pp. 705-711 ◽  
Author(s):  
G. Belforte ◽  
T. Raparelli ◽  
V. Viktorov ◽  
A. Trivella
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Darcy’S Law ◽  
Darcy's Law ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Thrust Pad ◽  
Gas Bearing ◽  
Forchheimer’S Law

In porous resistances, Darcy’s law provides a good approximation of mass flow rate when the differences between upstream and downstream pressures are sufficiently small. In this range, the mass flow rates are proportional to the porous resistance’s permeability. For gas bearings, the pressure difference is normally higher, and it is known experimentally that the mass flow rates are lower than would result from Darcy’s law. Forchheimer’s law adds an inertial term to Darcy’s law and, when an appropriate coefficient is selected for this term, provides a good approximation of flow rates for the same applications even with the highest pressure differences. This paper presents an experimental and theoretical investigation of porous resistances used in gas bearing and thrust pad supply systems. The porous resistances considered in the investigation were made by sintering bronze powders with different grain sizes to produce cylindrical inserts that can be installed in bearing supply devices. The paper describes the test setup and experimental results obtained for: (i) mass flow rate through single porous resistances at different upstream and downstream pressures and (ii) mass flow rate and pressure distribution on a pneumatic pad featuring the same porous resistances. The theoretical permeability of the chosen porous resistances was calculated, and the results from setup (i) were then used to obtain experimental permeability and to determine the inertial coefficients. The results, which are expressed as a function of the Reynolds number, confirmed the validity of using Forchheimer’s law. The mass flow rates from setup (ii) were compared to those from setup (i) at the same pressure differentials across the resistance.

First and second thermodynamic law analyses applied to a solar dish collector

2014 ◽  
Vol 39 (4) ◽  
Author(s):  
Vahid Madadi ◽  
Touraj Tavakoli ◽  
Amir Rahimi
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exergy Efficiency ◽  
Exergy Destruction ◽  
Flow Rates ◽  
Energy And Exergy ◽  
Mass Flow Rates

AbstractThe energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The effect of receiver type, inlet temperature and mass flow rate of heat transfer fluid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the effect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal efficiency. The cylindrical receiver has greater energy and exergy efficiency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy efficiency is minimum for a specified HTF mass flow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass flow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass flow rates than the above mentioned values are recommended.

Effect of nozzle angle, turbine inlets and mass flow rate on the performance of a bladeless turbine

2019 ◽  
Vol 234 (8) ◽  
pp. 1101-1107
Author(s):  
Muhammad Ali Kamran ◽  
Shahryar Manzoor
Keyword(s):  
Experimental Study ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Working Fluid ◽  
Operating Parameters ◽  
Lower Mass ◽  
Flow Rates ◽  
Significant Parameter ◽  
Mass Flow Rates

A comprehensive experimental study on the effects of different operating parameters on the efficiency of tesla turbine is reported. A bladeless turbine with nine discs and up to four turbine inlets was used, with water as the working fluid. The parameters investigated are the nozzle angle, number of turbine inlets and mass flow rates. Contrary to earlier studies, an effort was made to determine the performance under varying loading conditions, and hence identify the complete performance characteristics. The study revealed that efficiency of the turbine increases at lower nozzle angles and higher number of turbine inlets. It was observed that the nozzle angle becomes a significant parameter when the number of turbine inlets is increased. Efficiencies up to 78% were achieved when the working fluid entered the turbine through two nozzles at an angle of 7°. It was also noted that the turbine is most efficient at the designed mass flow rate, and the efficiency reduces appreciably if lower mass flow rates are fed to the turbine. The results obtained are an important contribution to the available knowledge and can be used as design references for further studies.

Optimization of the process of reproducing units of mass and volume of liquid in a stream, mass and volumetric flow rates of liquid for calibration units with weighing devices

2020 ◽  
pp. 60-64
Author(s):  
R. A. Korneev ◽  
A. R. Tukhvatullin ◽  
V. A. Fafurin ◽  
R. R. Nigmatullin ◽  
A. V. Shchelchkov
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Storage Tank ◽  
Experimental Studies ◽  
Working Fluid ◽  
Time Interval ◽  
Flow Rates ◽  
Wide Range ◽  
Flow Switch

The publication presents an experimental method for estimating the minimum time interval for filling a storage tank with a working fluid with a fixed geometry of the nozzle of the flow switch of the calibration plant when playing units of mass and volume of fluid in the flow, mass and volumetric flow rates of the fluid. Experimental studies were performed in a wide range of mass flow rate 11,10–83,26 kg/s (40–300 t/h) with repeated static weighing of the working fluid. The flow switch is made with a fixed geometry of the flow part of the nozzle exit, which is typical for a large number of calibration units in use in our country with weighing devices. The graphical dependences of the mass flow rate on the time of filling the storage capacity obtained from the research results are the basis for optimizing the process of reproducing units of mass and volume of liquid in the flow, mass and volumetric flow rates of the liquid for calibration plants with weighing devices. These graphical dependencies made it possible to formulate recommendations on the reasonable choice of the minimum interval for filling the storage tank with working fluid in the studied range of mass flow rate. Optimization has been tested and can be extended to calibration units with weighing devices from various manufacturers with individual design and operating parameters.

scholarly journals Experimental Study of the Slit Spacing and Bed Height on the Thermal Performance of Slit-Glazed Solar Air Heater

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Seyyed Mahdi Taheri Mousavi ◽  
Fuat Egelioglu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Ambient Air ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Flow Rates ◽  
Air Mass ◽  
Bed Height ◽  
Mass Flow Rates

The thermal performances of three slit-glazed solar air heaters (SGSAHs) were investigated experimentally. Three SGSAHs with different bed heights (7 cm, 5 cm, and 3 cm) were fabricated with multiple glass panes used for glazing. The length, width, and thickness of each pane were 154 cm, 6 cm, and 0.4 cm, respectively. Ambient air was continuously withdrawn through the gaps between the glass panes by fans. The experiments were conducted for four different gap distances between the glass panes (0.5 mm, 1 mm, 2 mm, and 3 mm) and the air mass flow rate was varied between 0.014 kg/s and 0.057 kg/s. The effects of air mass flux on the outlet temperature and thermal efficiency were studied. For the SGSAH with bed height of 7 cm and glass pane gap distance of 0.5 mm, the highest efficiency was obtained as 82% at a mass flow rate of 0.057 kg/s and the air temperature difference between the inlet and the outlet (∆T) was maximum (27°C) when the mass flow rate was least. The results demonstrate that for lower mass flow rates and larger gaps, the performance of SGSAH with a bed height of 3 cm was better compared to that of others. However, for higher mass flow rates, the SGSAH with 7 cm bed height performed better.

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