Investigating Trajectory Based Combustion Control Using a Controlled Trajectory Rapid Compression and Expansion Machine (CT-RCEM)

2021 ◽  
pp. 1-23
Author(s):  
Abhinav Tripathi ◽  
Zongxuan Sun
Keyword(s):  
Combustion Engine ◽  
Optimal Operation ◽  
Temperature History ◽  
Control Input ◽  
Combustion Control ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Compression And Expansion ◽  
Rapid Compression

Abstract This work presents a systematic framework for the real time implementation of a new combustion control strategy – trajectory-based combustion control – for the operation of free piston engines. The free piston engine is an alternative architecture of IC engines which does not have a mechanical crankshaft and hence allows extreme operational flexibility in terms of piston trajectory. The key idea of trajectory-based combustion control is to modulate the autoignition dynamics by tailoring the pressure and temperature history of the fuel-air mixture inside the combustion chamber, using the piston trajectory as the control input, for the optimal operation of the free piston engine. Here, we present the experimental investigation of trajectory-based combustion control using a novel instrument called controlled trajectory rapid compression and expansion machine (CT-RCEM) that can be used for studying a single combustion cycle of an internal combustion engine with precisely controlled initial and boundary conditions. The effect of the shape of the piston trajectory on the combustion phasing, combustion efficiency and the indicated thermal efficiency has been found to be significant. The experimental results indicate that the trajectory-based combustion control is an effective strategy for combustion phasing control for FPE operation.

scholarly journals Research of a Hybrid Diesel Locomotive Power Plant Based on a Free-Piston Engine

2020 ◽  
Vol 22 (3) ◽  
pp. 103-109
Author(s):  
Serhiy Buriakovskyi ◽  
Borys Liubarskyi ◽  
Artem Maslii ◽  
Danylo Pomazan ◽  
Tatyana Tavrina
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Diesel Generator ◽  
Piston Engine ◽  
Diesel Locomotive ◽  
Free Piston ◽  
Electric Transmission ◽  
Free Piston Engine ◽  
Hybrid Transmission

This article describes one of the possible ways for improving the energy efficiency of shunting diesel locomotives. It means a replacing a traditional traction electric transmission with a diesel generator set with a hybrid transmission with a free-piston internal combustion engine and a linear generator. The absence of a crankshaft in an internal combustion engine makes it possible to reduce thermal and mechanical losses, which, in turn, leads to an increase in the efficiency of traction electric transmission of the diesel locomotive.

New Free-Piston Topping Cycle for Gas-Turbine Power Plants

2003 ◽  
Author(s):  
William L. Kopko ◽  
John S. Hoffman
Keyword(s):  
High Performance ◽  
Power Plants ◽  
Waste Heat ◽  
Combustion Engine ◽  
Complete Recovery ◽  
Combined Cycle ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Topping Cycle

A proposed topping cycle inserts a free-piston internal-combustion engine between the compressor and the combustor of a combustion turbine. The topping cycle diverts air from the compressor to supercharge the free-piston engine. Because the free-piston engine uses gas bearings to support the piston and is built of high-temperature materials, the engine can increase the pressure and temperature of the gas, exhausting it to a small expander that produces power. The exhaust from the topping-cycle expander is at a pressure that can be re-introduced to the main turbine, allowing almost complete recovery of waste heat. A capacity increase exceeding 35% is possible, and overall cycle efficiency can approach 70% when incorporated into a state-of-the-art combined-cycle plant. The cost of per incremental kW of the topping cycle can be dramatically lower than that of the base turbine because of the high power density and simplicity of the engine. Building on decades of progress in combustion turbines systems, the new cycle promises high performance without the engineering risks of manufacturing a completely new cycle.

Transient Control of a Hydraulic Free Piston Engine

2013 ◽  
Author(s):  
Ke Li ◽  
Chen Zhang ◽  
Zongxuan Sun
Keyword(s):  
High Efficiency ◽  
Combustion Engine ◽  
Tracking Error ◽  
Control Signal ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Engine Operation ◽  
Free Piston Engine ◽  
Transient Period

The free piston engine (FPE) is a type of internal combustion engine (ICE) with no crankshaft, so that its piston motion is no longer constrained by mechanical linkages. The FPE has a high potential in terms of energy saving given its simple structure, high modularity and high efficiency. One of the technical barriers that prevents the wide spread of the FPE technology, is the lack of precise piston motion control. Previously, a robust repetitive controller is designed and implemented to form a virtual crankshaft that would provide a precise and stable engine operation. The experimental data of engine motoring tests with virtual crankshaft demonstrates the effectiveness of the controller. However, the presence of a transient period after a single combustion event prevents the engine from continuous firing. This paper presents a modified control scheme, which utilizes a reference and control signal shifting technique to modify the tracking error and the control signal to reduce the transient period.

Realizing Trajectory-Based Combustion Control in a Hydraulic Free Piston Engine via a Fast-Response Digital Valve

2018 ◽  
Author(s):  
Chen Zhang ◽  
Zongxuan Sun
Keyword(s):  
Chemical Kinetics ◽  
Thermal Efficiency ◽  
Fast Response ◽  
Combustion Control ◽  
Piston Engine ◽  
Free Piston ◽  
Frictional Loss ◽  
Switching Strategy ◽  
Hcci Combustion ◽  
Free Piston Engine

Previously, the authors have proposed the concept of piston trajectory-based combustion control enabled by a free piston engine (FPE) and shown its advantages on both thermal efficiency and emissions performance. The main idea of this control method is to design and implement an optimal piston trajectory into FPE and optimizes the combustion performance accordingly. To realize the combustion control in practice, it is obvious that the design of the optimal trajectory should consider the dynamic behaviors of the FPE’s actuation systems as well as variable load dynamics and fuels’ chemical kinetics. In this paper, a comprehensive model describing the operation of a hydraulic FPE fueled by diesel under HCCI combustion mode is developed. Such a high fidelity model includes four parts, i.e. the piston dynamics, the hydraulic dynamics, the thermodynamics and the fuel’s chemical kinetics. Extensive simulation results are produced, showing that by varying the switching strategy of a fast-response digital valve, the hydraulic FPE can operate at different working loads in a stable manner. Additionally, analysis has been conducted to quantify the thermal efficiency as well as the frictional loss and throttling loss of the FPE. At last, a feedback control is developed to generate optimal switching strategies for the digital valve aimed to achieve the HCCI combustion phasing control. The resulted switching strategy of the digital valve not only increases the thermal efficiency by 0.76%, but also reduces frictional loss by 9.8%, throttling loss by 6.5% as well as NOx emission by 85.6%, which clearly demonstrates the effectiveness of the trajectory-based combustion control.

scholarly journals Effects of Injector Spray Angle on Performance of an Opposed-Piston Free-Piston Engine

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3735
Author(s):  
Qinglin Zhang ◽  
Zhaoping Xu ◽  
Shuangshuang Liu ◽  
Liang Liu
Keyword(s):  
Combustion Engine ◽  
Fluid Dynamic ◽  
Combustion Process ◽  
Three Dimensional ◽  
Mixture Distribution ◽  
Combustion Efficiency ◽  
Spray Angle ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

A free-piston engine is a novel internal combustion engine which has the advantages of a variable compression ratio and multi-fuel adaptability. This paper focuses on numerical simulation for combustion process and spray angle optimization of an opposed-piston free-piston engine. The working principle and spray-guided central combustor structure of the engine are discussed. A three-dimensional computational fluid dynamic model with moving mesh is presented based on the tested piston motion of the prototype. Calculation conditions, spray models, and combustion models were set-up according to the same prototype. The effects of spray angle on fuel evaporation rate, mixture distribution, heat release rate, in-cylinder pressure, in-cylinder temperature, and emissions were simulated and analyzed in detail. The research results indicate that the performance of the engine was very sensitive to the spray angle. The combustion efficiency and the indicated thermal efficiencies of 97.5% and 39.7% were obtained as the spray angle reached 40°.

scholarly journals Wall Heat Transfer Analysis of Internal Combustion Engine with Free Piston Linear Motion

2018 ◽  
Vol 7 (3.17) ◽  
pp. 141
Author(s):  
Mior A. Said ◽  
L K. Mun ◽  
A R. A. Aziz ◽  
. .
Keyword(s):  
Heat Transfer ◽  
Transfer Rate ◽  
Combustion Engine ◽  
Linear Motion ◽  
Piston Engine ◽  
Piston Motion ◽  
Free Piston ◽  
Free Piston Engine ◽  
Set Up ◽  
Motion Profile

The manuscript should contain an abstract. The abstract should be self-contained and citation-free and should not exceed 200 words. The abstract should state the purpose, approach, results and conclusions of the work.  The author should assume that the reader has some knowledge of the subject but has not read the paper. Thus, the abstract should be intelligible and complete in it-self (no numerical references); it should not cite figures, tables, or sections of the paper. The abstract should be written using third person instead of first person. Intensive researches are being carried out on the main power generator for free piston linear generator(FPLG) by both the academic and industrial research group due to its potential as a high fuel efficiency and low emission engine. The linear generator, which is a coil and a translator positioned to move linearly back and forth relative to each other. The study investigates the heat transfer data of internal combustion engine with free piston linear motion profile and compared with the conventional reciprocating engine for one cycle motion only. Engine simulation software GT-Power is employed which utilize the 1-D thermodynamic modeling. All parameters for both free-piston engine are set-up to be the same except for the piston motion profile and the injection timing. Both conventional and free piston engine models are built, simulation settings are set up, and simulations are launched in GT-ISE.  Once simulation is done, results are viewed in GT-POST, the data collected was analysed and compared to investigate the dictinct effect of piston motion to heat transfer profile and data. The overall trend shows that free piston engine have a lower heat transfer rate throughout majority of the cycle. This finding agrees that due to less time of piston near top dead centre area, heat transfer losses to the wall per cycle are reduced. The heat transfer profile of the free piston also shown distinct feature compared to conventional with rapid increase and decrease of heat transfer rate, followed by a secondary peak of gradual decline of the profile.  

Numerical investigation into the fuel evaporation and mixture formation characteristics of a free-piston diesel engine

2019 ◽  
Vol 21 (7) ◽  
pp. 1180-1192
Author(s):  
Chenheng Yuan ◽  
Cuijie Han ◽  
Mian Yang ◽  
Yan Zhang
Keyword(s):  
Combustion Chamber ◽  
Ignition Delay ◽  
Combustion Engine ◽  
Combustible Mixture ◽  
Fuel Spray ◽  
Piston Engine ◽  
Free Piston ◽  
Injection Process ◽  
Free Piston Engine ◽  
Mixing Characteristics

The free-piston engine generator becomes a new-type potential substitute for the conventional crankshaft combustion engine. This article presents a simulation to study the fuel spray and mixing characteristics of a diesel free-piston engine generator by comparing a corresponding crankshaft combustion engine. A full-cycle model which couples with piston dynamics, combustion, and gas exchange is developed to simulate the fuel spray, atomization, and mixing in the free-piston engine generator. The result indicates that compared with the crankshaft combustion engine, the free-piston engine generator provides a higher temperature and pressure for fuel spray and mixing during the ignition delay, but its ignition delay lasts shorter. The free-piston engine generator shows a shorter spray penetration and more fuel impingement due to its smaller combustion chamber volume during the injection process. The free-piston engine generator exhibits a lower level of air utilization and worse uniformity of fuel–air mixture in combustion chamber. In addition, the shorter ignition delay of free-piston engine generator makes the time of atomization, evaporation, and mixing of fuel shorter, and the mixing effect of free-piston engine generator is worse, resulting in less combustible mixture formed during the ignition delay. In addition, some guiding suggestions have been proposed to improve the fuel spray and fuel–air mixing characteristics of free-piston engine generator.

Free Piston Engine Based Mobile Fluid Power Source

2016 ◽  
Author(s):  
Keyan Liu ◽  
Chen Zhang ◽  
Zongxuan Sun
Keyword(s):  
Combustion Engine ◽  
Power Source ◽  
Fluid Power ◽  
Piston Engine ◽  
Free Piston ◽  
Load Pressure ◽  
Control Effectiveness ◽  
Free Piston Engine ◽  
Output Flow ◽  
Working Principle

As a novel alternative of internal combustion engine (ICE), the free piston engine (FPE) eliminates the mechanical crankshaft and the associated constraints on its piston motion. Due to this extra degree of freedom and reduced inertia, the FPE is able to generate variable output power with higher efficiency and less emissions, while possessing a short response time. Hence, a hydraulic FPE (HFPE), which combines the FPE with a linear hydraulic pump, is a promising candidate as a fluid power source, especially for mobile applications. In this paper, such potential is investigated. The working principle of a prototype HFPE as a fluid power source is described and a comprehensive HFPE model is developed. Two novel control methods are proposed to regulate the output flow rate at any given load pressure so as to realize throttle-less fluid power control. Effectiveness of these two methods are demonstrated through simulation, where results clearly show the effectiveness of both methods in providing different output flow rates at given load pressure, thus demonstrating the HFPE’s capability as an efficient and flexible mobile fluid power source.

scholarly journals Investigations for a Trajectory Variation to Improve the Energy Conversion for a Four-Stroke Free-Piston Engine

2021 ◽  
Vol 11 (13) ◽  
pp. 5981
Author(s):  
Robin Tempelhagen ◽  
Andreas Gerlach ◽  
Sebastian Benecke ◽  
Kevin Klepatz ◽  
Roberto Leidhold ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Alternative Fuels ◽  
Internal Combustion Engines ◽  
Combustion Process ◽  
Optimal Operation ◽  
Combustion Engines ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine ◽  
Future Work

Internal combustion engines with a crankshaft have been successfully developed for many years. They are lacking in the fact that the piston trajectory, i.e., position as a function of time, is limited by the crankshaft motion law. Position-controlled electric linear machines directly coupled to the piston allow to realize free-piston engines. Unlike the crankshaft-based engines, they allow for a higher degree of freedom in shaping the piston trajectory, including adaptive compression ratios, which enables optimal operation with alternative fuels. The possibility of adapting the stroke course results in new degrees of freedom with which the combustion process can be optimized. In this work, four-stroke trajectories with different amplitudes and piston dynamics have been proposed and analyzed regarding efficiency. A simulation model was created based on experimental measurements for testing the proposed trajectories. It could be proved that the variation of the trajectory resulted in an improvement of the overall efficiency. The trajectories were described analytically so that they can be used for a prototype in a future work.

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