miller cycle
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Introduction (problem statement and relevance). The object of research in this work is an inline six-cylinder gas engine 6ChN13/15 with a Miller thermodynamic cycle. On the basis of its computer model studies minimization of the specific effective fuel consumption has been reached due to variation study of gas distribution and air supply systems parameters.The purpose of the study was to investigate the parameters regulation effect of gas distribution and air supply systems on the performance of a 6ChN13/15 gas engine with a Miller cycle on the external speed characteristic basing on numerical modeling.Methodology and research methods. The research was carried out by the method of computer simulation. Numerical modeling was made on the basis of data obtained during a full-scale experiment of a 6ChN13/15 gas engine with Miller thermodynamic cycle.Scientific novelty and results. A comparative analysis of a gas engine optimization results has been carried out. The results obtained will be used to create a gas engine and its further optimization by controlling the working process and the air supply system.Practical significance. The results obtained may be of interest to truck car manufacturers and engine specialists.

With the increase of the engine intensified degree, mechanical load and thermal load become to the two main factors limiting the engine to intensify. Application of Miller cycle, which can be realized by late intake valve closing (LIVC) and deeper late intake valve closing (DLIVC), has the potential to reduce the effective CR, mechanical load, and thermal load. In this paper, the effects of LIVC and DLIVC on the mechanical load and thermal load of a boosted DI diesel are experimentally compared. Compared to the original base case, the average cylinder temperature of LIVC and DLIVC is reduced by 90 and 52 K. The exhaust temperature of LIVC and DLIVC decreased by 26 and 14 K, and the maximum combustion pressure of LIVC and DLIVC decreased by 1.6 and 9.7 bar. The pumping losses of LIVC and DLIVC are reduced by more than 25%, while the actual cycle power does not decrease due to the late closing of the inlet valve. The fuel consumption rate decreased from 250.1 g/kWh of base case to 240 g/kWh of LIVC, reduced by 4.0%. The indicated thermal efficiency increased from 41.9% of base case to 43.7% and 42.5% of LIVC and DLIVC. Miller loss is only 2.55% with Miller inlet phase.

Abstract The article presents the results of a 1D numerical simulation of a spark ignition engine developed to operate in Miller cycle. Miller cycle offers better thermal efficiency compared to Otto cycle due to higher volumetric expansion than compression, which in the current context is of paramount importance. In an engine with fixed geometric compression ratio, Miller cycle operation could be realized by means of either early intake valve closing (EIVC) or late intake valve closing (LIVC). Both cases lead however to a lower volumetric efficiency, thus reducing the indicating mean effective pressure, which in its turn results to a lower power output. The simulation’s aim is not only to assess the impact of implementing the Miller cycle but also to obtain the necessary results for imposing the boundary conditions in a 3D CFD simulation whose purpose is to analyse the influence of the Miller cycle on the internal aerodynamics of the engine.

To achieve higher brake thermal efficiency (BTE) and improve vehicle economy, the new development of dedicated hybrid engine (DHE), adopting the Atkinson or Miller cycle, has been becoming the current development trends. A base 1.5L natural aspiration (NA) engine with deep Atkinson cycle has been developed for dedicated hybrid vehicle application, which can achieve the highest BTE of 41.19%. In order to achieve higher BTE, several potential technologies which are easy for mass production application have been studied progressively, such as, higher compression ratio (CR), optimized exhaust gas recirculation (EGR) pick point, lower EGR temperature, higher EGR rate, higher RON number fuels, heat transfer reduction by polishing valve head, light boost, lower viscosity oil. The results show the combined technology application can achieve the highest engine BTE of 42.59%. This paper provides the studied technical routine and the achieved benefits step by step.

This study experimentally investigates the impact of extreme Miller cycle strategies paired with high intake manifold pressures on the combustion process, emissions, and thermal efficiency of heavy-duty diesel engines. Well-controlled experiments isolating the effect of Miller cycle strategies on the combustion process were conducted at constant engine speed and load (1160 rpm, 1.76 MPa net IMEP) on a single cylinder research engine equipped with a fully-flexible hydraulic valve train system. Late intake valve closing (LIVC) timing strategies were compared to a conventional intake valve profile under either constant cylinder composition, constant engine-out NOx emission, or constant overall turbocharger efficiency ([Formula: see text]) to investigate the operating constraints that favor Miller cycle operation over the baseline strategy. Utilizing high boost with conventional intake valve closing timing resulted in improved fuel consumption at the expense of sharp increases in peak cylinder pressures, engine-out NOx emissions, and reduced exhaust temperatures. Miller cycle without EGR at constant [Formula: see text] demonstrated LIVC strategies effectively reduce engine-out NOx emissions by up to 35%. However, Miller cycle associated with very aggressive LIVC timings led to fuel consumption penalties due to increased pumping work and exhaust enthalpy. LIVC strategies allowed for increased charge dilution at the baseline NOx constraint of 3.2 g/kWh, resulting in significant fuel consumption benefits over the baseline case without compromising exhaust temperatures or peak cylinder pressures. As Miller cycle implementation was shown to affect the boundary conditions dictating [Formula: see text], the LIVC and conventional IVC cases were studied at an equivalent [Formula: see text] point representative of high boost operation. With high boost, LIVC yielded reduced NOx emissions, reduced peak cylinder pressures, and elevated exhaust temperatures compared to the conventional IVC case without compromising fuel consumption.

The article is devoted to the study of the possibilities of improving the technical and economic indicators of an internal combustion engine (ICE) through the use of the Miller cycle with a shortened intake. A review of scientific works on the use of the Atkinson cycle and Miller cycle in an internal combustion engine is carried out. A comparative analysis of theoretical cycles: Otto cycle, Atkinson cycle and Miller cycle is carried out. Calculated studies of the influence of the expansion ratio and the pressure increase ratio on the efficiency of the Atkinson cycle have been carried out. The ratios are presented that allow using the Miller cycle with a short inlet to obtain the same theoretical efficiency of the cycle as that of the Atkinson cycle. At the same time, the implementation of the Miller cycle in a real engine design significantly exceeds the possibilities of using the Atkinson cycle. The results of the study showed that the use of the Miller cycle with a shortened intake is preferable, but it must necessarily increase the compression ratio and intake pressure through the use of boost. On the example of real data of the main parameters of the cycle, it is shown that the use of the theoretical Miller cycle can provide a significant up to 12.2% increase in the efficiency of the cycle compared to the Otto cycle. The ratios, conditions and recommendations are presented that allow the effective use of the Miller cycle with a shortened intake in a real engine design.