Mathematical model for monitoring carbon dioxide concentration in industrial greenhouses

I. Laktionov¹*, O. Vovna¹, O. Cherevko² and T. Kozlovskaya³

¹State Higher Educational Institution 'Donetsk National Technical University', Ministry of Education and Science of Ukraine, Department of Electronic Engineering, Shibankova sq., 2, UA85300 Pokrovsk, Ukraine
²State Higher Educational Institution 'Priazovsky State Technical University', Ministry of Education and Science of Ukraine, Department of Automation and Computer Technologies, University str., 7, UA87500 Mariupol, Ukraine
³Kremenchuk Mykhailo Ostohradskyi National University, Department of biotechnologies and bioengineering, Pershotravneva str., 20, UA39600, Kremenchuk, Ukraine
*Correspondence: ivan.laktionov@donntu.edu.ua

Abstract:

Processes of monitoring and control the industrial greenhouses microclimate play a decisive role in growing crops under protected cultivation. Providing optimal climatic conditions in the production process of greenhouse agricultural products requires solving the scientific and applied problem of developing and researching a mathematical model for monitoring carbon dioxide concentration in industrial greenhouses. The proposed model takes into account the processes of diffusion and absorption of carbon dioxide, the geometric parameters of greenhouses, as well as the types and vegetation periods of crops grown under protected cultivation. Time characteristics of the carbon dioxide dynamics process under greenhouse conditions are estimated. Quantitative estimates of the diffusion transfer duration and carbon dioxide absorption are made for indeterminate varieties of tomatoes during planting and fruiting periods. Recommendations are given on the development of an adaptive methodology for the functioning and structural and algorithmic organization of computerized monitoring and management system for carbon dioxide top-dressing modes for greenhouse crops. The necessity of improving the proposed mathematical model and confirming the adequacy of its implementation efficiency on yield indicators of greenhouse crops is substantiated.

Key words:

Automatic control and maintaining of cooling process of bakery products

A. Pastukhov

ITMO University, Saint-Petersburg, Russia;
e-mail: artem.pastukhov¹⁹⁸⁴@gmail.com

Abstract:

During the development of automation control of the bakery products cooling process using a ‘cooler’ it is necessary to build an integrated control system, which allows to optimize the process parameters in case of a variety of work situations that may occur in the bakery enterprise. The main task for control of such multifactorial object is to reach a certain temperature in the center of the product by maintaining the temperature of the cooling air near the surface of the loaf set in the limits t ± Δt, its velocity v ± Δv and humidity φ ± Δφ, and maintain the speed of the conveyor within Vc ± ΔVc using the frequency converters. Simultaneous exposure to multiple channels of control allows selecting the optimal combination of the cooling process control commands, yielding the product with necessary temperature and mass. Automatic control and regulation of the cooling process is based on the fact that the current value of the adjustable parameters in mismatch block is compared with predetermined values of the corresponding parameters, and the mismatch signals are formed, which are amplified to a value sufficient to trigger actuators that provide executive regulators. Novelty of the paper consists in the development of the process control system based on the mathematical model which allows calculating the temperature at the center of freshly baked products by the surface temperature of the product at any time of location in the cooling zone. Experiments were carried out on the bread made in the laboratory and cooled after baking, by natural and forced convection. Baking was conducted in a special parallelepiped tins with lids. Thus, the output product had a parallelepiped shape. Process of cooling by natural convection was implemented in a cooling chamber, which allowed to measure temperature and relative humidity. Temperatures changing in the center of the loaf and weight loss were recorded during the experiments. Cooling time was determined by the time required to achieve the temperature in the center of the loaf 30°C. On the basis of the experimental data a mathematical model and the computer system, allowing calculating the parameters of cooling and in time to make a regulatory influence on one of the control channels and thus optimize the process parameters were built.

Key words:

automation, heat transfer, mass transfer, spiral conveyor.