Математичне моделювання процесу охолодження насипу зерна як об'єкта з розподіленими параметрами

В. О. Грищенко, О. Д Курганський, Б. І. Котов

Анотація


UDC 664.723

MATHEMATICAL MODELING OF THE COOLING PROCESS OF THE GRAIN PULP, AS OBJECTS WITH DISTRIBUTED PARAMETERS

V. O. Hryshchenko, A. D. Kurgan, B. I. Kotov

 

Post-harvest grain processing is an indispensable condition for preserving the harvested crop in storage facilities, and is an energy-intensive process that needs to be improved and to find promising grain drying directions.

Now the problem of increasing the resistance to storage of freshly harvested crop of grain crops at the place of their production is urgent.

Recent studies [1, 2] have found it promising to use the technology of cooling grain material directly in storage facilities by venting the mound with cold air. In this case, the machine (steam-compressor refrigeration units) is used to cool the air [3]. Despite the significant volumes of grain stored in the farms and the corresponding capacities of the refrigeration units, the optimal modes of periodic cooling [1] can be realized only by means of automatic control. To synthesize an automatic control system for temperature cooling modes, it is necessary to have the dynamic characteristics of the object, preferably in the form of transfer functions [4] through the appropriate channels, since a grain mound of a sufficiently high layer is vented, it is necessary to take into account the distribution of the object's parameters with the coordinate in the direction of the filtered air movement.

Existing mathematical models describe [5] the dynamics of thermal processes, complex transcendental functions, the use of which makes synthesis of the ACS difficult and its subsequent analysis.

To determine the dynamic characteristics of the simulation object, the analytical-calculation method is used, the essence of which is as follows: on the basis of a priori information on the physical picture of the phenomena occurring when the grain layer interacts with a source of heat (biochemical) with cooling air, the heat balance equations in differential form in private Derivatives, which determine the gradients of air parameters in height. The solution of the system of equations for the steady-state regime determines the distribution of the sought parameters along the height of the embankment and the value of the gradients in the coordinate function [6]. In this case, partial differential equations are replaced by ordinary differential equations, the linearization of which is carried out by conventional methods [6].

Conclusions.

1. Simulation of Grain cooling allows approximate formulas to recreate the process of changing temperature and grain moisture in time and highest layer.

2. The resulting block diagram of a linear mathematical model can be used for analysis and synthesis of automatic control of the cooling process of grain in storage.


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