Improving the working conditions of combine harvester operators when exposed to intense solar radiation

There have been considered the working conditions of combine harvester operators under the influence of solar radiation, as well as have been tested some methods for determining the heat inflow into the cabin of a combine harvester. The first method involved an engineering calculation using an approximate technique that takes into account the light transmission of the walls, their thickness and surface area, as well as the thermal characteristics of the materials from which they are made. Computer modeling in the Ansys simulation software environment was used as the second method for determining the heat inflow from solar radiation. To do this, a three-dimensional virtual full-size model of the combine's cabin was built, which was subsequently divided into a certain number of finite tetrahedral elements, each of which being used to solve a mathematical model. The mathematical model was given by the equation of radiation transfer in discrete ordinates and allowed calculations of heat transfer through translucent and massive cabin barriers. To simulate sunlight radiation effects entering the computational domain based on location, time and date, a solar load model was also selected and implemented by the Ansys software - a solar calculator. According to the results of calculations using engineering methods, the heat inflow through the opaque walls of the combine harvester cabin at an ambient temperature of + 40 °C is equal to 336,2 W, the heat inflow through the light area is 1447,7 W. The results of computer modeling show that the heat inflow through the upper opaque wall of the combine harvester cabin averages 167,1 W, which is generally close to the result of engineering calculation with a relative error of 9,36%. However, the value of heat inflow through the light area being equal to 754,4 W indicates the low accuracy of the engineering calculation method compared with computer modeling (relative error is 41,01%), which ultimately may lead to the choice of a less efficient climate system, since its cooling capacity will not be sufficient to ensure the microclimate parameters inside the cabin comfortable for a machine operator.