Study of air parameters during drying of large-block metal structures in a tent-type drying chamber

Abstract

One of the stages in the manufacture of large-block metal structures is their coloring followed by drying. A feature of this process is the need to maintain a temperature determined by the characteristics of the paint, which is difficult at low ambient temperatures. The solution of the problem is the use of a tent-type mobile drying chamber at the stage of drying the painted part at the place of its assembly. At the same time, the drying process can be controlled by changing the location of the fan heater and exhaust ventilation, changing the performance of the heater fan and the temperature of the supplied air. The solution of this technological problem is the goal of the study. The study uses the methods of numerical modeling and experimental studies. As a modeling tool, the SOLIDWORKS software package and office packages for statistical data processing have been used. It is found out that the distribution of temperatures in the shelter depends on the thermal resistance of the walls of the drying chamber, the main characteristic of the heater fan, the dimensions of the chamber and the painted module, the gaps between the walls, the ambient temperature and the air coming from the heater, the fan parameters, the fan placement methods and draft ventilation. The calculation considers the aerodynamic resistance of the drying chamber with the part placed in it, the influence of free convection, heat loss and features of air distribution inside the shelter. Based on the results obtained, the authors proposed a calculation method that allows determining the temperature decrease inside the chamber relative to the temperature of the air coming from the heater. To automate the calculation results, a program has been developed to determine the parameters of air after heating with a fan heater. The results obtained makes it possible to solve an important practical problem of ensuring high quality of painting works in a tent-type shelters under various climatic conditions, including negative ambient temperatures due to a reliable forecast of the uneven temperature field in the painting chamber. The developed technique is designed for the rapid selection of heaters, including the supply of a fan, the power of the heating element, and the air temperature at the outlet of the heater depending on the ambient temperature, the permissible range of temperature changes of the paint, the geometric parameters of the tent shelter and the painted product. The scientific value of the study is the results of the study of mixed convection in the tent shelter, the revealed essential regularities of the process and the obtained criterion equation to calculate the temperature range of the paint coating of the product in the chamber. The obtained results have determined the ways to further increase of energy efficiency and to improve the design of tent shelters.