scholarly journals Simultaneous Air Fraction and Low-Pressure EGR Mass Flow Rate Estimation for Diesel Engines

2013 ◽  
Vol 46 (2) ◽  
pp. 731-736 ◽  
Author(s):  
F. Castillo ◽  
E. Witrant ◽  
V. Talon ◽  
L. Dugard
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diesel Engines ◽  
Low Pressure ◽  
Rate Estimation

Effect of the Leakage Flows and the Upstream Platform Geometry on the Endwall Flows of a Turbine Cascade

2006 ◽  
Author(s):  
E. de la Rosa Blanco ◽  
H. P. Hodson ◽  
R. Vazquez
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Separation Bubble ◽  
Tangential Velocity ◽  
Low Pressure ◽  
Leakage Flow ◽  
Backward Facing Step ◽  
Surface Separation ◽  
Pressure Surface

This work describes the effect that the injection of leakage flow from a cavity into the mainstream has on the endwall flows and their interaction with a large pressure surface separation bubble in a low-pressure turbine. The effect of a step in hub diameter ahead of the blade row is also simulated. The blade profile under consideration is a typical design of modern low-pressure turbines. The tests are conducted in a low speed linear cascade. These are complemented by numerical simulations. Two different step geometries are investigated, i.e., a backward-facing step and a forward-facing step. The leakage tangential velocity and the leakage mass flow rate are also modified. It was found that the injection of leakage mass flow gives rise to a strengthening of the endwall flows independently of the leakage mass flow rate and the leakage tangential velocity. The experimental results have shown that below a critical value of the leakage tangential velocity, the net mixed-out endwall losses are not significantly altered by a change in the leakage tangential velocity. For these cases, the effect of the leakage mass flow is confined to the wall, as the inlet endwall boundary layer is pushed further away from the wall by the leakage flow. However, for values of the leakage tangential velocity around 100% of the wheelspeed, there is a large increase in losses due to a stronger interaction between the endwall flows and the leakage mass flow. This gives rise to a change in the endwall flows structure. In all cases, the presence of a forward-facing step produces a strengthening of the endwall flows and an increase of the net mixed-out endwall losses when compared with a backward-facing step. This is because of a strong interaction with the pressure surface separation bubble.

A Model for EGR Mass Flow Rate Estimation

1997 ◽  
Author(s):  
P. M. Azzoni ◽  
G. Minelli ◽  
D. Moro ◽  
G. Serra
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rate Estimation

scholarly journals Validated Analytical Modeling of Diesel Engines Intake Manifold with a Flexible Crankshaft

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1287
Author(s):  
Salah A.M. Elmoselhy ◽  
Waleed F. Faris ◽  
Hesham A. Rakha
Keyword(s):  
Mass Flow Rate ◽  
Relative Error ◽  
Mass Flow ◽  
Flow Rate ◽  
Diesel Engines ◽  
Analytical Modeling ◽  
Vacuum Pressure ◽  
Analytical Models ◽  
Intake Manifold ◽  
Flow Losses

The flexibility of a crankshaft exhibits significant nonlinearities in the analysis of diesel engines performance, particularly at rotational speeds of around 2000 rpm. Given the explainable mathematical trends of the analytical model and the lack of available analytical modeling of the diesel engines intake manifold with a flexible crankshaft, the present study develops and validates such a model. In the present paper, the mass flow rate of air that goes from intake manifold into all the cylinders of the engine with a flexible crankshaft has been analytically modeled. The analytical models of the mass flow rate of air and gas speed dynamics have been validated using case studies and the ORNL and EPA Freeway standard drive cycles showing a relative error of 7.5% and 11%, respectively. Such values of relative error are on average less than those of widely recognized models in this field, such as the GT-Power and the CMEM, respectively. A simplified version for control applications of the developed models has been developed based on a sensitivity analysis. It has been found that the flexibility of a crankshaft decreases the mass flow rate of air that goes into cylinders, resulting in an unfavorable higher rate of exhaust emissions like CO. It has also been found that the pressure of the gas inside the cylinder during the intake stroke has four elements: a driving element (intake manifold pressure) and draining elements (vacuum pressure and flow losses and inertial effect of rotating mass). The element of the least effect amongst these four elements is the vacuum pressure that results from the piston's inertia and acceleration. The element of the largest effect is the pressure drop that takes place in the cylinder because of the air/gas flow losses. These developed models are explainable and widely valid so that they can help in better analyzing the performance of diesel engines.

Dynamic Reference Value Generation for the Control of a Diesel Engine With HP- and LP-EGR

2010 ◽  
Author(s):  
Matthias Mrosek ◽  
Rolf Isermann
Keyword(s):  
High Pressure ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exhaust System ◽  
Reference Value ◽  
Low Pressure ◽  
Gas Composition ◽  
Air Mass ◽  
Intake System

A combination of a low-pressure EGR and a high-pressure EGR for Diesel engines can effectively reduce the NOx emissions. In comparison to a conventional high-pressure EGR, the combination with a low-pressure EGR introduces an additional degree of freedom for the air path control. From control perspective the weaker couplings with the charging pressure and the dynamics of the gas composition in the intake and exhaust system are the major differences between the low-pressure and the high-pressure EGR. The lower gas temperature of the low-pressure EGR further reduces the emissions. A control oriented model is presented to control the gas composition in the intake system. Therefore a reference value transformation converts a desired air mass flow rate into a desired gas composition in the intake system. Depending on the dynamical gas compositions in the intake and exhaust system, the reference value of the desired gas composition results in a setpoint for a high-pressure EGR mass flow rate controller. Due to the faster dynamics of the high-pressure EGR, this controller accounts for the fast dynamical effects in the gas system. The presented control structure in combination with the reference value generation is invariant to model and sensor uncertainties and results stationary in an air mass flow rate control. As additional control variable, the intake temperature is controlled by the low-pressure EGR mass flow rate. A calibrated desired temperature delivers the setpoint for a low-pressure EGR mass flow rate controller.

scholarly journals Modelling the Exhaust Gas Recirculation Mass Flow Rate in Modern Diesel Engines

2016 ◽  
Author(s):  
Zhijia Yang ◽  
Edward Winward ◽  
Gary O'Brien ◽  
Richard Stobart ◽  
Dezong Zhao
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diesel Engines ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Recirculation

Optimal Allocation of Heat Exchanger Inventory for Maximum COP and Exergetic Performance of a Two-Stage Vapor Compression Cycle

2013 ◽  
Author(s):  
Yousef M. Abdel-Rahim ◽  
S. A. Sherif
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Load ◽  
Low Pressure ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Exergetic Efficiency

In the present study the optimum heat exchanger inventory allocation to maximize the thermal performance of a two-stage vapor compression system with two evaporators has been investigated. Both the cooling (A/C) and heating (H/P) Carnot and non-Carnot non-isentropic cycles have been considered. The optimum operating ranges of cycle parameters that maximize both the coefficient of performance (COP) and exergetic efficiency (η2) of the cycles for both cooling and heating purposes are discussed. The research upon which this paper partly reports covered all possible ranges of cycle parameters using the Monte-Carlo method. For the Carnot cycle, maximum values of the cooling coefficient of performance (COPC), cooling exergetic efficiency (ηIIC), heating coefficient of performance (COPH), and heating exergetic efficiency (ηIIH) were found to be 9.6, 0.47, 10.7 and 0.87, respectively. The low-pressure (LP) thermal load and temperature difference in the condenser were found to critically affect both the A/C and H/P performance, while the heat conductance ratio and the mass flow rate ratio were found to have a pronounced effect on only the H/P performance. The best A/C and H/P cycle performance may be achieved by having the two evaporators with both the thermal load and mass flow rate in the high-pressure loop to be 20% less than that in the low-pressure loop. The analysis performed on the non-Carnot two-compressor, two-evaporator A/C and H/P non-isentropic cycles determined both the feasible and optimal ranges of variations of the controlling parameters. The combined maximum values of the low- and high-pressure evaporator thermal loads was found to be 10–15% lower than the maximum value of the condenser heat rejection rate, thus reflecting the relative sizes of these units as heat exchangers. Other factors that may help provide guidance for utilizing the system for cooling and heating purposes include the values of the COPC and COPH, the relative amounts of the mass flow rates in the low-pressure and high-pressure loops of the cycle, and the values of the low-pressure and high-pressure compressor powers.

Effect of the Leakage Flows and the Upstream Platform Geometry on the Endwall Flows of a Turbine Cascade

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
E. de la Rosa Blanco ◽  
H. P. Hodson ◽  
R. Vazquez
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Separation Bubble ◽  
Tangential Velocity ◽  
Low Pressure ◽  
Leakage Flow ◽  
Backward Facing Step ◽  
Surface Separation ◽  
Pressure Surface

This work describes the effect that the injection of leakage flow from a cavity into the mainstream has on the endwall flows and their interaction with a large pressure surface separation bubble in a low-pressure turbine. The effect of a step in hub diameter ahead of the blade row is also simulated. The blade profile under consideration is a typical design of modern low-pressure turbines. The tests are conducted in a low speed linear cascade. These are complemented by numerical simulations. Two different step geometries are investigated, i.e., a backward-facing step and a forward-facing step. The leakage tangential velocity and the leakage mass flow rate are also modified. It was found that the injection of leakage mass flow gives rise to a strengthening of the endwall flows independently of the leakage mass flow rate and the leakage tangential velocity. The experimental results have shown that below a critical value of the leakage tangential velocity, the net mixed-out endwall losses are not significantly altered by a change in the leakage tangential velocity. For these cases, the effect of the leakage mass flow is confined to the wall, as the inlet endwall boundary layer is pushed further away from the wall by the leakage flow. However, for values of the leakage tangential velocity around 100% of the wheel speed, there is a large increase in losses due to a stronger interaction between the endwall flows and the leakage mass flow. This gives rise to a change in the endwall flows’ structure. In all cases, the presence of a forward-facing step produces a strengthening of the endwall flows and an increase of the net mixed-out endwall losses when compared with a backward-facing step. This is because of a strong interaction with the pressure surface separation bubble.

scholarly journals Verification and Comparison of Nine Exhaust Gas Recirculation Mass Flow Rate Estimation Methods

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7291
Author(s):  
Ádám Nyerges ◽  
Máté Zöldy
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Estimation Methods ◽  
Exhaust Gas ◽  
Flow Rates ◽  
Air Mass ◽  
Rate Estimation ◽  
Mass Flow Rates ◽  
Gas Recirculation

Modern Diesel engines have complex exhaust gas recirculation (EGR) systems. Due to the high temperatures, it is a typical issue to measure EGR mass flow rates in these complex control systems. Therefore, it is expedient to estimate it. Several sensed values can help the estimation: the fresh air mass flow rate, the fuel consumption, pressures, temperatures and mass fractions in the air path system. In most of the articles, the EGR mass flow rate estimation is done by the pressures. However, gas composition based models usually would be better for control aims. In this paper, nine EGR estimation methods will be presented: an important outcome is to present the required sensor architectures and estimation challenges. The comparison will be made by measurement results both in stationary operation points and transient cycles. The estimated EGR mass flow rates will be evaluated by verification conditions. The results will prove that the intake and exhaust side oxygen sensors can give verifiable signals for EGR mass flow rate estimation. In contrast, the applied fresh air mass flow rate and the nitrogen-oxide signals are not accurate enough to provide verifiable EGR mass flow rates in every operating condition. The effects of sensor inaccuracies will also be considered.

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