The application of modified thermodynamic system correction method to secondary reheat steam turbine

In order to calculation the enthalpy of wet steam in the secondary reheat turbine thermal system the thermodynamic system of the secondary reheat steam turbine based on the isentropic ideal expansion process line was corrected, This method simplifies the correction calculation step and increases the accuracy of the correction result. Analysis of the rationality of the improved method shows that: Compared with the existing secondary reheat steam turbine thermal system correction method, the maximum error of the improved thermal system correction method is 0.14%. Therefore, this method can better meet the test accuracy requirements.

THE CONCEPT OF THE PASSENGER CAR LIFE CYCLE

The article deals with the issues of a conceptual approach to determining the life cycle of a passenger car. The fleet of passenger car mainly consists of models developed and manufactured in the 70-90s of the last century at car plants in Germany and Russia. They are obsolete both morally and physically. This necessitates the renewal of the passenger car fleet by purchasing cars of both domestic and foreign production. In modern conditions, the user of new technology is interested not only in the purchase price, but also in the after-sales costs. This is reflected in the life cycle cost. It is proposed to use a cascade life cycle model for a passenger car. The stages of the life cycle of a passenger car during operation on the railways of Ukraine have been determined. The components of each stage of the life cycle of a passenger car are considered. For a transport company that intends to operate a passenger car, the costs of the first three stages are directly expressed in the initial cost of the car - the purchase price. The life cycle cost (LCC) of a passenger car will be determined by summing up the individual outflow of funds (expenses) at each specific stage (calculation step) of the service life of the equipment. The life cycle assessment of the technical system of railway transport can work at any stage of the life cycle.

A Study on Anti-Shock Performance of Marine Diesel Engine Based on Multi-Body Dynamics and Elastohydrodynamic Lubrication

Diesel engine anti-shock performance is important for navy ships. The calculation method is a fast and economic way compared to underwater explosion trial in this field. Researchers of diesel engine anti-shock performance mainly use the spring damping model to simulate the main bearings of a diesel engine. The elastohydrodynamic lubrication method has been continuously used in the main bearings of diesel engines in normal working conditions. This research aims at using the elastohydrodynamic lubrication method in the main bearings of the diesel engine in external shock conditions. The main bearing elastohydrodynamic lubrication and diesel engine multi-body dynamics analysis is based on AVL EXCITE Power Unite software. The external shock is equivalent to the interference on the elastohydrodynamic lubrication calculation. Whether the elastohydrodynamic lubrication algorithm can complete the calculation under interference is the key to the study. By adopting a very small calculation step size, a high number of iterations, and increasing the stiffness of the thrust bearing, the elastohydrodynamic lubrication algorithm can be successfully completed under the external impact environment. The calculation results of the accelerations on engine block feet have a similar trend as the experiment results. Diesel engines with and without shock absorbers in external shock conditions are calculated. This calculation model can also be used for diesel engine dynamics calculations and main bearing lubrication calculations under normal working conditions.

Development of the Method for Predicting and Calculating the Operation of Sorption Systems for Cleaning the Generator Gas based on Dolomite Use. Part II

At present, instead of a direct combustion of solid fuel, its thermochemical conversion is exten-sively used to produce a generator gas. The use of this technology is connected with the need for gas purification. One of the promising and widely spread sorbents for the purification of the generator gas is dolomite, whose particles compose the active component of the bed filters. Forecasting the technological characteristics of the functioning of the bed filters of a various de-sign is an extremely urgent task. The objective of the study is to develop a method for forecast-ing and calculating the operation of sorption systems for purification of the generator gas based on dolomite. It is achieved by constructing and verifying a mathematical model of the function-ing of the bed sorption filter with a radial-axial flow pattern of the generator gas through the do-lomite filling. The Markov chains theory of a mathematical apparatus is used to design the one-dimensional mathematical model of the process with discrete space and time. The main recurrent balance ratio is formed at each calculation step taking into account the current characteristics of the process, which makes the model nonlinear. The significance of the research is that an approach to the problem of increasing the reliability of the description and reliability of forecasting technological processes in a bed filter was proposed based on the construction of mathematical models of these processes, in which the filter is considered as a system with distributed characteristics, and the calculation was based on local exchange potentials between particles and gas.

Control-oriented modeling of the gas exchange process in rebreathing homogeneous charge compression ignition engines

The purpose of this study is to develop a model for the gas exchange process in a rebreathing homogeneous charge compression ignition (HCCI) engine. HCCI engines are attracting significant attention due to their low emissions and high efficiency. To design the control system of an HCCI engine, it is necessary to develop a control-oriented engine model. The developed model lowers its computational load by combining two types of models. The model consists of a discrete model for the exhaust process (the first half of the gas exchange process) and a continuous model with a variable calculation step size for the rebreathing process (the latter half of the gas exchange process). Also, the constructed model maintained its prediction accuracy, as the pressure pulsation in the exhaust port was modeled, and an unsteady flow equation was used. It was confirmed that the model developed for the gas exchange process calculated in about half time of one cycle and reproduced the results of 1D engine simulation software with a maximum error of about 10% in the in-cylinder pressure, temperature, and trapped mass.

Modular Approach for Modelling Warming Up Process in Water Installations with Flow-Regulating Elements

The paper presents a new method for modelling the warming up process of a water system with elements regulating the flow in a stochastic manner. The paper presents the basic equations describing the work of typical elements which the water installation is composed of. In the proposed method, a new computational algorithm was used in the form of an iterative procedure enabling the use of boundary conditions that can be stochastically modified during the warming-up process. A typical situation, when such a modification is processed, is the regulation of the medium flow through two-way or three-way valves or applying additional heat source. Moreover, the presented method does not require the transformation of the differential equations, describing the operation of individual elements, into a linear form, which significantly facilitates analytical work and makes it more flexible. The example of analysis of the operation of water installation used for controlling temperature of the process gases in a chemical installation shows the functionality and flexibility of the method. The adopted calculation schematics enable changing the direction of the heat flow while the heat exchanger is in operation. Additionally, the sequence of calculation processed in modules describing operation of installation elements is elective (there is no situation that output parameters from one element are used as input parameters for other element in the same calculation step).

Voltage Regulation For Residential Prosumers Using a Set of Scalable Power Storage

Among the electrical problems observed from the solar irradiation variability, the electrical energy quality and the energetic dispatch guarantee stand out. The great revolution in batteries technologies has fostered its usage with the installation of photovoltaic system (PVS). This work presents a proposition for voltage regulation for residential prosumers using a set of scalable power batteries in passive mode, operating as a consumer device. The mitigation strategy makes decisions acting directly on the demand, for a storage bank, and the power of the storage element is selected in consequence of the results obtained from the power flow calculation step combined with the prediction of the solar radiation calculated by a recurrent neural network Long Short-Term Memory (LSTM) type. The results from the solar radiation predictions are used as subsidies to estimate, the state of the power grid, solving the power flow and evidencing the values of the electrical voltages 1-min enabling the entry of the storage device. In this stage, the OpenDSS (Open distribution system simulator) software is used, to perform the complete modeling of the power grid where the study will be developed, as well as simulating the effect of the overvoltages mitigation system. The clear sky day stored 9111 Wh/day of electricity to mitigate overvoltages at the supply point; when compared to other days, the clear sky day needed to store less electricity. On days of high variability, the energy stored to regulate overvoltages was 84% more compared to a clear day. In order to maintain a constant state of charge (SoC), it is necessary that the capacity of the battery bank be increased to meet the condition of maximum accumulated energy. Regarding the total loading of the storage system, the days of low variability consumed approximately 12% of the available capacity of the battery, considering the SoC of 70% of the capacity of each power level.

Design Multistage External Gear Pumps for Dry Sump Systems: Methodology and Application

Thanks to their manufacturing simplicity, robustness, and consolidated design knowledge, external gear pumps are widely adopted in the automotive fields. With the purpose of leading the design procedure of these positive displacement machines, within this work, the authors integrate in a comprehensive tool the salient equations adopted for the design of the major gear pump features. The presented procedure is devoted to the design of multistage external gear pumps characterized by a singular floating driving shaft supported by fluid-dynamic journal bearings. Focusing the attention on the procedure flexibility, it has been structured in three iterative calculation phases. The core section of the methodology concerns the geometrical design of the involute gear tooth profile. It is oriented to ensure a proper volumetric displacement while complying with the space requirement and the tooth manufacturing limitations. Thus, through the analytical pressure loads estimation combined with the operational parameters, the second calculation step provides the design of the driving shaft and the relevant dimensions of the journal bearings. Finally, by means of a power loss approach, the third macrosection of the procedure leads to estimating the clearances between gear tip and housing. The potentials of the methodology are exposed by describing its applications to a case study of multistage gear pump employed in the dry sump lubrication system of an automotive heavy-duty engine. Each calculation step application is outlined with reference to the proposed analytical formulation and the results of the parameters calibration are presented. Within this context, the procedure is assessed by means of a CFD analysis. The results highlight the accuracy of the methodology on the estimation of the required delivery flow rate. Aside from being accurate, flexible, and reliable, the procedure stands out for being an innovative tool within the multistage gear pump framework.

ANALISIS SIX SIGMA DENGAN DECISION ON BELIEF CHART PADA PRODUK HOT STRIP MILL

The Decision On Belief (DOB) control chart is a univariate control chart that was initially introduced as a solution to the problem of less than optimal control limits from the shewhart attribute diagram, especially the control chart C. The new scheme based on the DOB control chart is that the calculation step , can change the data which initially is not normally distributed into a normal distribution, then can diagnose quality control process errors. . defines belief or an assumption in the new observation vector and . The aim of this research is to apply the DOB control chart to data that is not normally distributed, so that it becomes a normal distribution. The result of the DOB control chart shows that the value of . is between the BKA and BKB values, which indicates a statistically controlled process. In this study, using one specification limit, namely the upper specification limit (USL) given by the company, which is 15 percent of the average production. The capability index used is for 3 sigma using the transformation result . Based on the sample data, the result shows that the value is 0.40633 and the sigma level is 2.719, so it can be concluded that the Hot Strip Mill production process is still not capable and has not reached the level of three sigma.Keywords: Six Sigma, Decision On Belief, capability index, , DPMO, level sigma.