Model prediction and measured data of NOx in the h

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Comparative analysis of NOx model prediction

and observed data for 4JB1 diesel engine Nanchang University Gao Guozhen Lu Zhijun

(Nanchang 330029) Abstract Isuzu trucks are converted into locally made ones in Jiang Xi Province at order to enable the locally made trucks meet the requirements of emissions standards and raise the competitive ability the indicator diagram of Jiang 4JB1 high speed four stroke direct injection vehicle1 Diesel engine is obtained through high speed data acquisition en the data are at release through combination is analyzed, And NOx emissions concentration is analysis parametric analysis is made for calculated and observed NOx e law of NOx emissions versus operation and structural parameters is e pressure testing machine has been designed safely and reasonably before manufacturing oretic basis is provided for reducing hazardous pollutants from locally made diesel e comparison of calculated results and observed data shows that the combination model intr oduced in the paper is applicable for NOX prediction in 4JB1 diesel engine.

key words direct injection diesel engine, mechanism of NOx formation, indicator diagram, analysis computation1 preface

the automobile industry is developing rapidly, the number of cars is increasing, and the exhaust gas pollution to the atmospheric environment is becoming increasingly serious. People pay more and more attention to the problems of cars and the earth's environment, and the importance of reducing harmful emissions from cars is increasing. At present, any technology related to vehicle performance lacks technical value without considering the role of emissions, so emissions are becoming the key to the development of automotive engines

nox is one of the main environmental pollutants in automobile exhaust

nox is not only harmful to human body and the environment, but also difficult to control. Therefore, the concentration of harmful emissions of 4JB1 diesel engine is calculated numerically, and the generation characteristics of harmful emissions are revealed through calculation. The variation law, especially the NOx generation characteristics and variation law, can provide theoretical data for the future emission performance research of Jiangling Automobile Engine after localization. At the same time, it is also a beneficial work to integrate with the increasingly stringent international emission standards

2 determination of indicator diagram data of 4JB1 diesel engine

the numerical calculation of NOx concentration of 4JB1 diesel engine is based on the analysis of heat release law and combustion process by using the indicator diagram. Before the program calculation, the pressure in the cylinder must be measured through experiments to obtain and avoid the use of organic solvents. A more accurate indicator diagram is the key of this calculation

1 - corner signal generator 2 - charge amplifier 3 - sc42 type a/d board 4 - oscilloscope 5 - printer 6 - plotter 7 - microcomputer 8 - Display 9 - general engine test bench 10 - speed sensor 11 - eddy current dynamometer 12 - fuel consumption instrument 13 - Exhaust thermometer 14 - pressure sensor 15 - oil thermometer 16 - oil pressure gauge 17 - cooling water thermometer Figure 1 test and analysis experimental system device figure 2.1 collection of indicator diagram data

4jb1 diesel engine indicator diagram data acquisition adopts a high-speed data acquisition system to measure the pressure in real time

the high-speed data acquisition system is mainly composed of ibm-pc5xb6 microcomputer, sc42 type a/d-d/a multi-function board, sensor, crankshaft angle generator, charge amplifier, printer, digital plotter and other instruments. Its core is microcomputer and sc42 multi-function Board [1]. The device diagram of the experimental system is shown in Figure 1, and the working principle of the high-speed acquisition system is shown in Figure 2. Fig. 2 working principle of high-speed acquisition, test and analysis system Fig. 2.2 indicator diagram pressure data processing

2.2.1 pressure value calibration

the value collected by the supporting measurement system composed of microcomputer and sc42 type a/d-d/a multi-function acquisition board is only the electric analog quantity transformed by the piezoelectric quartz sensor under the pressure signal, which is amplified by the charge amplifier, and then converted by sc42 type a/d-d/a multi-function board. These data must be calibrated and converted into actual pressure before they are meaningful. The pressure value calibration of the pressure electric signal value is carried out on the test bench of the standard pressure verification pump (yv-600 piston pressure gauge) [2]

2.2.2 calibration of top dead center

in order to make the data obtained by the acquisition system correspond to the measured crankshaft angle of the engine one by one, the dynamic top dead center must be calibrated, because of the dynamic influence of the combustion process, in fact, the top dead center often deviates from the static top dead center position. The position error of TDC has a great influence on the calculation accuracy of heat release rate. When the TDC deviation is 1 degree, the peak value of the heat release rate will produce an error of 3% - 5%, and the maximum error of the percentage of the heat release rate is 7% - 9%. Therefore, it is very important to correctly determine the position of TDC [2]

2.2.3 fairing of indicator diagram data

the combustion models we use are based on the assumption that the pressure in the combustion chamber is uniform. In order to eliminate the random error and pressure fluctuation of the indicator diagram data, and make the discrete data continuously differentiable to meet the requirements of calculating the heat release rate, and then to calculate the NOx concentration, the pressure curve of the indicator diagram must be smoothed first [2]

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