Search

The calculation of the fluid flow in the interscapular channel of a centrifugal impeller with a finite number of blades, the construction of the energy characteristics of the impeller and its optimization by the number of vanes are considered. The calculation consists of two parts: firstly, the determination of the theoretical pump head taking into account the effect of a finite number of vanes based on the analysis of the force interaction, and, secondly, the determination of hydraulic losses in the impeller by integrating the friction stresses over the limiting surfaces. The results from both parts are used to optimize the number of vanes in the pump impeller.

The basic provisions of the mathematical model of a condenser-evaporator in relation to air separation units are considered. All influencing quantities are shown, the main component blocks are highlighted, and the sequence of their solution is given. The model is based on a joint solution of the equations of hydrodynamics and heat transfer for tubular apparatuses using iterative calculations to clarify the initial values of the determining parameters both within individual blocks and between blocks. Application of the model is possible for both design and verification calculations with minimal changes. The development of the considered model is associated with the adaptation of its algorithm to machine calculation. One of the main directions is the inclusion of a database of parameters of working substances in the field of vapor-liquid states with the ability to automatically search and transfer the required thermophysical parameters on the evaporation and condensation lines in the model.

The thermal calculation, which is part of the mathematical model of a condenser-evaporator of cryogenic air separation plants, is considered. The calculation is based on solving the criteria equations of heat exchange for cases of condensation outside of the pipe and evaporation inside the pipe. The thermal calculation is preceded by a hydraulic calculation, the results of which are used as input quantities. The solution is carried out by a multistep (iterative) method. The heat flow density on the evaporation side is used as a criterion for convergence of iterations. The calculation scheme, divided into successive steps, is shown. The calculation results are used to determine the geometric configuration and the main characteristics of the condenser-evaporator.

The hydraulic calculation, which is part of a mathematical model of a condenser-evaporator of a cryogenic air separation plant, based on the multi-step (iterative) method of equation of the hydrodynamic balance of a circuit with natural circulation.

This paper analyzes various types of startup systems used for the heat and power facility start-up. Factors impacting startup characteristics of the heat and power facility were considered. Methods for the modernization of the startup system and possible revamping of auxiliary starting aid devices of locomotive diesel engines without significant design changes by means of cylinder test valve opening were identified. Kinematic diagrams of device gearing for automatic decompression of the heat and power facility cylinders were developed and analyzed. The device requirements were determined, namely, response time, cylinder test valve open and closing torque overriding Tmin=11 Nm. Based on the necessity of torque backup at least 30 % the gear ratio required for the selected engine and its dimensions was calculated.