Intrinsic Defects of Conventional Valve-training Mechanisms The conventional valve-training mechanism has its inherent drawbacks because the valve movement law, including the valve opening and closing time, the valve lift angle of the valve lift valve opening, and the like, are all determined by the profile of the valve cam. The phase of the valve cannot be changed with the operating conditions. For an engine, the cam profile has been determined. It is not possible to change the cam profile with the operating conditions of the engine during the working process. This results in the valve movement and the valve timing determined by the valve movement rule. It varies with engine operating conditions. This kind of valve mechanism can only meet the maximum efficiency of the engine under a certain working condition, while the inflation efficiency is reduced to some extent in other very wide working conditions. It is difficult to realize the variable technology of valve phase in order to make the valve phase change with the engine operating conditions, and to increase the charging efficiency of the engine under various working conditions as much as possible. The variable valve has been developed on the basis of the traditional valve distribution mechanism. Gas phase valve mechanism.
There are two kinds of variable valve timing gas distribution mechanisms currently used, and the valve is controlled by the cam to open and close. One type is the variable valve mechanism of the camshaft, which is used by the computer according to the engine operating conditions. The need to control the hydraulic system changes the relative angular position of the intake camshaft and the intake camshaft timing gear or the toothed pulley or sprocket, thereby changing the valve timing. Because the cam profile has not changed, therefore, although the opening and closing timing of the intake valve has changed, the intake valve opening and continuation angle has not changed, and the change in valve overlap angle also does not correspond to the change of operating conditions. The phase of the exhaust valve also does not change.
The other type is a variable valve mechanism with a variable intake duration. It is equipped with two sets of intake cams on the intake camshaft, that is, low-lift and short-duration intake cams for medium-to-low-speed high-torque and high-speed high-power High lift long duration intake cam used. The two groups of cams are switched by the computer to control the hydraulic device according to the engine operating conditions. This variable system can meet the different requirements of high-speed and low-speed valve timing, ensuring good performance at high and low speeds, but the phase of the exhaust valve has not changed, and the structure is also very complicated and the layout is difficult, especially for the multi-valve structure. .
Results indicated that the inactivation of Escherichia coli in artificial wastewater was similar with that in real municipal wastewater. Among three waters, the bactericidal effect of chlorine dioxide was lowest in secondary effluent. The bacteria log inactivation increased by up to threefold when the COD concentration of raw wastewater was decreased by half. An unfavorable COD effect was also observed for the disinfection of secondary effluent. To explain the COD effect on bacteria inactivation, chlorine dioxide residuals were measured with time through each disinfection process. Results from statistical analyses have revealed that, in comparison to the correlations using CT values, the inactivation data can be better correlated with the ratio of COD to ClO2 concentrations. The results of this study would be a useful guide for many municipalities and communities in determining chlorine dioxide dosages for water and wastewater disinfection systems.
Wastewater Disinfection Chlorine Dioxide, Phenolic Wastewater Treatment, Sewage Treatment Chlorine Dioxide, Hospital Wastewater Treatment
Nanjing Ligong Shuifu Environmental Protection Technology Co.,Ltd. , https://www.watermanclo2.com