scholarly journals Analysis of the frequency characteristics of the control system for the processes of fuel supply to the cylinders of the power unit

2021 ◽  
pp. 9-16
Author(s):  
Anatoliy Borysenko ◽  
Oleksandr Yenikieiev ◽  
Dmitry Zakharenkov ◽  
Ihor Zykov
Keyword(s):  
Transfer Function ◽  
Computer System ◽  
Power Unit ◽  
Rotation Speed ◽  
Combustion Engine ◽  
Frequency Characteristics ◽  
Structural Diagram ◽  
Software Environment ◽  
Input Information ◽  
Discrete Transfer Function

The idea of monitoring the identity of the cylinder capacities of an internal combustion engine under conditions of incomplete information is proposed and a computer system is built on its basis. The signal of the instantaneous rotation speed of the crankshaft of the power unit was used as input information. In the development of the hardware architecture, injectors with piezoelectric actuators, the principle of direct digital control, and the principle of control with feedback on the state of fluctuations of the crankshaft rotation speed were used. The Laplace transform was used as a mathematical apparatus for analyzing the structural diagram of a computer system for programmed control of the processes of supplying fuel and air to the cylinders of the power unit. Mathematical models of the components of the hardware for controlling the processes of supplying the fuel-air mixture were constructed, and as a result of the analysis of the structural diagram of the computer system, the transfer function was obtained. Using the capabilities of the Matlab software environment, the transient and impulse transient characteristics of the system are obtained, the Nyquist hodograph is constructed, and the logarithmic amplitude-frequency characteristics of the hardware are established. It was found that the frequency characteristics of the mathematical model of a computer system have the necessary dynamic characteristics. Using the method of expansion into simple fractions, an expression is obtained for a discrete transfer function, the coefficients of the power polynomials of which are established using the method of determinants and computational capabilities of the Mathcad software environment. On the basis of a discrete transfer function, a scheme for computer modeling of the process of processing the signal of the instantaneous speed of rotation of the crankshaft by hardware is constructed. The output signal was obtained by computer simulation, as a result of the analysis of which the speed of the hardware for processing the input information was established.

Pulse-Width Modulated Amplifier for DC Servo System and Its Matlab Simulation

2015 ◽  
Vol 9 (1) ◽  
pp. 625-631
Author(s):  
Ma Xiaocheng ◽  
Zhang Haotian ◽  
Cheng Yiqing ◽  
Zhu Lina ◽  
Wu Dan
Keyword(s):  
Mathematical Model ◽  
Transfer Function ◽  
Input Signal ◽  
Pulse Width ◽  
Rotation Speed ◽  
Servo Motor ◽  
Matlab Simulation ◽  
Pulse Width Modulated ◽  
Signal Changes ◽  
The Relationship

This paper introduces a mathematical model for Pulse-Width Modulated Amplifier for DC Servo Motor. The relationship between pulse-width modulated (PWM) signal and reference rotation speed is specified, and a general model of motor represented by transfer function is also put forward. When the input signal changes, the rotation speed of the servo motor will change accordingly. By changing zeros and poles, transient performance of this system is discussed in detail, and optimal ranges of the parameters is recommended at the end of discussion.

scholarly journals Experimental Validation of a New Modeling for the Design Optimization of a Sliding Vane Rotary Expander Operating in an ORC-Based Power Unit

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4204 ◽  
Author(s):  
Fabio Fatigati ◽  
Marco Di Bartolomeo ◽  
Davide Di Battista ◽  
Roberto Cipollone
Keyword(s):  
Design Optimization ◽  
Power Unit ◽  
Waste Heat ◽  
Combustion Engine ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Computational Time ◽  
Manufacturing Cost ◽  
External Diameter ◽  
New Model

Sliding Rotary Vane Expanders (SVRE) are often employed in Organic Rankine Cycle (ORC)-based power units for Waste Heat Recovery (WHR) in Internal Combustion Engine (ICE) due to their operating flexibility, robustness, and low manufacturing cost. In spite of the interest toward these promising machines, in literature, there is a lack of knowledge referable to the design and the optimization of SVRE: these machines are often rearranged reversing the operational behavior when they operate as compressors, resulting in low efficiencies and difficulty to manage off-design conditions, which are typical in ORC-based power units for WHR in ICE. In this paper, the authors presented a new model of the machine, which, thanks to some specific simplifications, can be used recursively to optimize the design. The model was characterized by a good level of physical representation and also by an acceptable computational time. Despite its simplicity, the model integrated a good capability to reproduce volumetric and mechanical efficiencies. The validation of the model was done using a wide experimental campaign conducted on a 1.5 kW SVRE operated on an ORC-based power unit fed by the exhaust gases of a 3 L supercharged diesel engine. Once validated, a design optimization was run, allowing to find the best solution between two “extreme” designs: a “disk-shaped”—increasing the external diameter of the machine and reducing axial length—and by a “finger-shaped” machine. The predictions of this new model were finally compared with a more complex numerical model, showing good agreement and opening the way to its use as a model-based control tool.

scholarly journals Design and Operational Control Strategy for Optimum Off-Design Performance of an ORC Plant for Low-Grade Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5846
Author(s):  
Fabio Fatigati ◽  
Diego Vittorini ◽  
Yaxiong Wang ◽  
Jian Song ◽  
Christos N. Markides ◽  
...  
Keyword(s):  
Power Unit ◽  
Control Strategy ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Combustion Engine ◽  
Working Fluid ◽  
Thermal Source ◽  
Low Grade ◽  
Gear Pump

The applicability of organic Rankine cycle (ORC) technology to waste heat recovery (WHR) is currently experiencing growing interest and accelerated technological development. The utilization of low-to-medium grade thermal energy sources, especially in the presence of heat source intermittency in applications where the thermal source is characterized by highly variable thermodynamic conditions, requires a control strategy for off-design operation to achieve optimal ORC power-unit performance. This paper presents a validated comprehensive model for off-design analysis of an ORC power-unit, with R236fa as the working fluid, a gear pump, and a 1.5 kW sliding vane rotary expander (SVRE) for WHR from the exhaust gases of a light-duty internal combustion engine. Model validation is performed using data from an extensive experimental campaign on both the rotary equipment (pump, expander) and the remainder components of the plant, namely the heat recovery vapor generator (HRVH), condenser, reservoirs, and piping. Based on the validated computational platform, the benefits on the ORC plant net power output and efficiency of either a variable permeability expander or of sliding vane rotary pump optimization are assessed. The novelty introduced by this optimization strategy is that the evaluations are conducted by a numerical model, which reproduces the real features of the ORC plant. This approach ensures an analysis of the whole system both from a plant and cycle point of view, catching some real aspects that are otherwise undetectable. These optimization strategies are considered as a baseline ORC plant that suffers low expander efficiency (30%) and a large parasitic pumping power, with a backwork ratio (BWR) of up to 60%. It is found that the benefits on the expander power arising from a lower permeability combined with a lower energy demand by the pump (20% of BWR) for circulation of the working fluid allows a better recovery performance for the ORC plant with respect to the baseline case. Adopting the optimization strategies, the average efficiency and maximum generated power increase from 1.5% to 3.5% and from 400 to 1100 W, respectively. These performances are in accordance with the plant efficiencies found in the experimental works in the literature, which vary between 1.6% and 6.5% for similar applications. Nonetheless, there is still room for improvement regarding a proper design of rotary machines, which can be redesigned considering the indications resulting from the developed optimization analysis.

scholarly journals Vibroacoustic methods of assessing valve clearance in combustion engines* An analysis of signals in the area of frequency

2010 ◽  
Vol 142 (3) ◽  
pp. 76-81
Author(s):  
Grzegorz Szymański ◽  
Franciszek Tomaszewski
Keyword(s):  
Combustion Engine ◽  
Frequency Characteristics ◽  
Combustion Engines

This article presents results of research referring to applying selected frequency characteristics of signal of vibration accelerations of combustion engine’s head to assess valve clearance of combustion engine. The authors indicate necessity to perform preliminary preparations of signal of vibration accelerations before carrying out frequency analyses in order to decrease the risk of inaccurate analysis.

scholarly journals Precision Engine for Nanobiomedical Research

2021 ◽  
Vol 3 (4) ◽  
pp. 01-05
Author(s):  
Afonin SM
Keyword(s):  
Transfer Function ◽  
Transfer Coefficient ◽  
Energy Conversion ◽  
Transfer Functions ◽  
Equivalent Circuits ◽  
Structural Diagram

The transfer function and the transfer coefficient of a precision electromagnetoelastic engine for nanobiomedical research are obtained. The structural diagram of an electromagnetoelastic engine has a difference in the visibility of energy conversion from Cady and Mason electrical equivalent circuits of a piezo vibrator. The structural diagram of an electromagnetoelastic engine is founded. The structural diagram of the piezo engine for nanobiomedical research is written. The transfer functions of the piezo engine or are obtained.

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