Control-oriented modeling, validation, and interaction analysis of turbocharged lean-burn natural gas variable speed engine

Accurate modeling and control of the gas exchange process in a modern turbocharged spark-ignited engine is critical for the control and analysis of different control strategies. This paper develops a simple physics-based, five-state engine model for a large four-stroke spark-ignited turbocharged engine fueled by natural gas that is used in variable speed applications. The control-oriented model is amenable for control algorithm development and includes the impacts of modulation to any combination of four actuators: throttle valve, bypass valve, fuel rate, and wastegate valve. The control problem requires tracking engine speed to provide propulsive power, differential pressure across the throttle valve to prevent compressor surge, air-to-fuel ratio to restrict engine emissions. Two validation strategies, open-loop and closed-loop, are used to validate the accuracy of both nonlinear and linear versions of the control-oriented model. The control models are able to capture the engine dynamics within 5%–10% error at most of the engine operating points. Finally, the relative gain array (RGA) is applied to the linearized engine model to understand the degree of interactions between plant inputs and outputs as a function of frequency for various operating points. Results of the RGA analysis show that the preferred input-output pairing changes depending on the linear plant model as well as frequency. Therefore, a coordinated controller is ideal to tackle the control problem in question.

Research on Precise Control of a Cylinder Delay Oscillation System Based on Response Surface and Genetic Algorithm

A cylinder time-delay oscillation system can be constructed by using air bag and throttle valve. The air bag and throttle valve are used to realize the time-delay transmission of pressure in the feedback circuit, and the feedback pressure is used to promote the reversing of two position five-way valve, so as to realize the reciprocating action of the cylinder. The experimental design is carried out based on the simulation analysis, and the response surface is constructed based on the experimental data to clarify the relationship between the cylinder dwell time and the main component parameters. Based on response surface, genetic algorithm is used to search for the best control parameters to realize the accurate control of cylinder dwell time.

Performance Improvement of KCS (Kalina Cycle System) 34 by Replacing Throttle Valve With Single-Screw Expander

In order to recover the energy loss due to the throttling in the path of ammonia-lean solution in the Kalina Cycle System (KCS) 34, two redesigned cycles, in which single-screw expanders that can perform two-phase expansion are used to replace the throttle valve, are proposed in this paper. The results show that the thermal efficiency and net work of two redesigned cycles are higher than those of the original KCS 34. With the concentration increase of ammonia-water mixture, the work produced by the single-screw expander B in two redesigned cycles gradually decreases, and the difference between the work produced in two redesigned cycles also gradually decreases. The original KCS 34 and two redesigned cycles have high exergy efficiency. The highest cycle exergy efficiency of 56.59% can be obtained in the II-redesigned cycle when the evaporation pressure is 3.0 MPa and ammonia-water concentration is 0.75.

PENGARUH VARIASI DIAMETER PIPA ISAP TERHADAP KARAKTERISTIK POMPA SENTRIFUGAL

Penelitian ini bertujuan mengetahui pengaruh variasi diameter ipa isap terhadap karakteristik pompa sentrifugal.Penelitian dilakukan terhadap pompa sentrifugal merk SHIMIZU PS – 128 BIT dengan daya input 125 Watt.Diameter pipa isap yang digunakan berukuran ½, ¾, dan 1 inci sedangkan diameter pipa tekan yang digunakanberukuran ¾ inci. Pada pipa tekan ditempatkan sebuah katup cekik (throttle valve) yang diatur bukaannya untukmengatur kapasitas air yang dipompa sehingga karakteristik pompa sentrifugal dapat dihitung berdasarkan besaranbesaranyang diukur. Hasil penelitian menunjukan bahwa diameter pipa isap berpengaruh terhadap karakteristik pompasentrifugal yang secara umum ditunjukan oleh nilai efisiensi pompa. Efisiensi poma tertinggi sebesar 0,79 dicapaipompa dengan diameter pipa isap 1 inch diikuti berturut-turut oleh pompa dengan diameter pipa isap ¾ inci dan ½ inciyakni 0,66 dan 0,21.

Failure Mechanism and Optimization of Throttle Valve Based on Computational Fluid Dynamics

Throttle valve is an important device in well control manifold. During field use, the seat and plug of the valve often fail of erosion, posing a serious security risk to well control. Erosion resistance device is a tool to counter the problem. Using the three-dimensional (3D) flow field analysis software of computational fluid dynamics (CFD), this paper numerically simulates the flow field of erosion resistance device. The results show that, under the given boundary conditions, the mean velocity of the water flow does not change much as it passes through the inlet and outlet of erosion resistance device. The flow velocity changes very slightly, as the fluid pressure difference varies from 0.29MPa to 0.3MPa. The maximum flow velocity (16.36m/s) appears on the outlet wall of the device, beneath the alloy head. The alloy head, which is made of hard alloy material, is not greatly affected by the maximum velocity. Thus, the erosion resistance device will not be severely eroded. This means the erosion resistance device can work normally under actual conditions.

2 loop Nonlinear Dynamic Inversion Fuel Flow Controller Design for Air to Air Ducted Ramjet Rocket

Fuel Flow controller based ramjet propulsion system have a flexibility to change rocket velocity depending on guidance requirement by controlling the fuel flow rate as a function of atmospheric conditions like altitude, Mach no. and angle of attack. In this paper, Design objectives & requirements of fuel flow controller have been brought out from guidance loop for air-to-air target engagement. 2-loop non-linear dynamic inversion (DI) based controller design has been proposed to track the commanded thrust and to meet the time constant requirement as a function of altitude, Mach no. and angle of attack. The outer thrust loop is to control commanded thrust and to generate the demand for gas generator pressure loop and inner pressure loop is to meet outer loop demand by controlling throttle valve area. The engine state space plant model has been adapted with improvement of existing model. Throttle valve actuator specifications requirement are also brought out.

Operational and economic analysis of a Velox-type combined heat & power plant with a throttle valve

For many years, the Department of Power Engineering and Turbomachinery of the Silesian University of Technology has been using a small-capacity (about 500 kWe) steam-gas power plant. Based on many years of experience in operation of this power plant utilizing the Velox-type gas-steam system, an idea arose to modify this type of thermal power cycle to create a combined heat and power (CHP) plant of small capacity, dedicated for distributed heat and power production or production process steam with high temperature. Previous thermodynamic and economic analysis of that type of low-power CHP plant confirmed many advantages of using this type of solution in low-power engineering. The new idea is to add a throttle valve between the economizer and the evaporator for the reference cycle of the gas-steam Velox-type CHP plant. It was further assumed that water would partially be vaporized on the valve. This paper presents a thermodynamic and economic analysis of this type of a system with an added throttle valve. Downstream the valve, the evaporated water fraction is fed directly into the steam superheater. It is determined how such a retrofit affects the system thermodynamic and economic characteristics. The system is modelled in the EBSILON® Professional 14 software.