scholarly journals Computational studies of the influence of variable valve timing on the performance of a gas engine with Miller’s thermodynamic cycle

2021 ◽  
Vol 2061 (1) ◽  
pp. 012066
Author(s):  
K V Milov
Keyword(s):  
Internal Combustion Engines ◽  
Computer Modelling ◽  
Thermodynamic Cycle ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Miller Cycle ◽  
Valve Timing ◽  
Gas Engine ◽  
Lift Height ◽  
Variable Valve

Abstract Current development trends in the field of internal combustion engines aim at regulating all processes of the engine and individual units. A converted diesel to gas engine with Miller thermodynamic cycle is more energy efficient at partial loads than a gas engine with Otto thermodynamic cycle. The Miller cycle engine with variable valve timing and valve lift has been investigated to improve performance and energy efficiency across the load range. The aim of the work is to study the influence of the displacement of the valve timing phases of the intake and exhaust camshafts and the valve lift height on the performance of the gas engine with the Miller cycle. Computer modelling was based on data obtained from the full-scale experiment on the gas engine with the Miller thermodynamic cycle.

Variable Valve Timing (VVT) Modelling by Lotus Engine Simulation Software

2021 ◽  
Vol 17 (4) ◽  
Author(s):  
Mohammed Kadhim Allawi ◽  
Mohanad Kadhim Mejbel ◽  
Mahmood Hasan Oudah
Keyword(s):  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
Simulation Software ◽  
Valve Lift ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Engine Simulation ◽  
Engineering Software ◽  
And Performance ◽  
Variable Valve

Variable valve timing (VVT) is an advanced modern technique applied in internal combustion engines by altering the valve lift event timing. This work aims to contribute to the continuing industrial VVT development to improve engine efficiency, fuel consumption and performance. To observe the influence on the spark-ignition (SI) engine’s performance, four valve timing strategies are selected carefully by varying the intake and exhaust valve timing. Lotus Engine Simulation, a simulation engineering software, is adapted in this study. The engine characteristics used in this modelling are spark engine, multicylinder, four strokes, port injection fuel system and constant compression ratio. A comparison between a conventional standard exhaust/intake valve timing and three other different timing cases is carried out. Results reveal that the overlap case of 98° showed a good brake-specific fuel consumption by approximately 3% less than the conventional case. An improvement of 6.2% for volume efficiency and 2.9% in brake thermal efficiency is also reported.

scholarly journals Miller Cycle Analysis Using EGM

2005 ◽  
Author(s):  
Bernardo Ribeiro ◽  
Jorge Martins
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Compression Ratio ◽  
Internal Combustion Engines ◽  
Combustion Engines ◽  
Miller Cycle ◽  
Valve Timing ◽  
Entropy Generation Minimization ◽  
Flow And Heat Transfer ◽  
Variable Valve

The Entropy Generation Minimization (EGM) method is based on the analysis by three sciences (thermodynamics, fluid flow and heat transfer) of the different processes that may occur in a system or in an equipment. Herein the EGM method is applied to internal combustion engines to determine the entropy generation caused by different processes. A model incorporating entropy generation calculations is used to assess various engines configurations. Otto cycle was tested and Variable Valve Timing (VVT) and Variable Compression Ratio (VCR) were applied so thermodynamic benefits could be tested and evaluated. With the referred model, the Miller cycle variables are analyzed in order to establish the best working conditions of an engine under a certain load. The intake and exhaust valve timing, combustion start, compression ratio adjustment and heat transfer are the variables for which a best working condition is determined based on the minimization of the entropy generation of the several engine processes.

Effects of Supercharging, EGR and Variable Valve Timing on Power and Emissions of Hydrogen Internal Combustion Engines

2008 ◽  
Vol 1 (1) ◽  
pp. 647-656 ◽  
Author(s):  
Sebastian Verhelst ◽  
Jannick De Landtsheere ◽  
Frederik De Smet ◽  
Christophe Billiouw ◽  
Arne Trenson ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Variable Valve Timing ◽  
Combustion Engines ◽  
Valve Timing ◽  
Variable Valve

Optimum Design of a BLDC Motor for Electric Continuous Variable Valve Timing System

2017 ◽  
Author(s):  
Soo-Whang Baek
Keyword(s):  
Optimum Design ◽  
Design Process ◽  
Internal Combustion Engines ◽  
Continuous Variable ◽  
Variable Valve Timing ◽  
Bldc Motor ◽  
Valve Timing ◽  
Maximum Torque ◽  
Cogging Torque ◽  
Variable Valve

In order to save resources and prevent global warming, it has been urgently needed to reduce CO2 emissions and decrease automobile fuel consumption in recent years. The trend in automotive applications are being studied to improve fuel efficiency and to reduce volume and weight. For these reasons, the mechanical parts of the automobile are being replaced by electric components. This paper deals with the optimum design process for a small Brushless DC (BLDC) motor used in Electric-Continuous Variable Valve Timing (E-CVVT) system in automobiles with internal combustion engines. It is also proposed to improve the rated efficiency and the maximum torque and reduce the cogging torque to improve the characteristics of the BLDC motor. To maximize the maximum torque as well as to maintain the rated efficiency, the radial basis function based on latin hypercube sampling and genetic algorithm are utilized. The design variables, objective functions, and constraints are selected for the optimum design of the BLDC motor, which is divided into three steps. Step I and step II are calculated to improve the rated efficiency and the maximum torque respectively, while step III utilizes to reduce cogging torque. To verify the proposed optimum design process, the improvement of characteristic is suggested with FE-analysis.

Variable Valve-Timing Unit Suitable for Internal Combustion Engines

1972 ◽  
Vol 186 (1) ◽  
pp. 301-306 ◽  
Author(s):  
G. E. Roe
Keyword(s):  
Internal Combustion Engines ◽  
Engine Speed ◽  
Valve Lift ◽  
Specific Power ◽  
Combustion Engines ◽  
Valve Timing ◽  
Specific Power Output ◽  
Torque Curve ◽  
Lift Curve ◽  
Variable Valve

As the specific power output of I.C. engines is increased, the range of engine speed over which useful torque is available is reduced. This ‘power band’ can be widened by having automatically varying valve timing, with the timing being a function of engine speed and/or load. A prototype cyclic phasing unit has been tested which successfully varies the timing of a poppet valve with opening, closing points, and the form of valve lift curve being readily varied independently. The unit is simple mechanically, but ideally one unit is needed for each valve, so principal application is likely to be on engines with a small number of cylinders. In addition to flattening the torque curve, such a unit is likely to give improved fuel consumption and lower exhaust emissions, particularly hydrocarbons.

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