ASSESSMENT OF THE IMPACT OF OPERATING CONDITIONS ON THE PERFORMANCE OF THE HYDRAULIC MINING EXCAVATOR WORKING FLUID COOLING SYSTEM
This paper provides an assessment of the influence of temperature operating conditions on the efficiency of the hydraulic system of mining excavators. The loss of power in the hydraulic system of hydraulic machines in general, and of a mining excavator in particular, sometimes reaches 25% of the total power supplied to the system. The energy, representing the power loss, is converted into heat energy, leading to heating of the working fluid (FR). The initial operating fluid temperature is the same as the ambient temperature and will increase rapidly as the hydraulic system operates. In the event that the temperature of the working fluid exceeds the maximum allowable, there are many negative effects in the hydraulic system, such as: decrease in: the performance of the hydraulic system; service life and lubricity of the fluid; the sealing effect of the working fluid; increase: intensity of wear; volumetric loss; failure rates; downtime and costs for repairs, replacement of faulty equipment, etc. An insignificant part of the heat from the working fluid is released into the environment through the body of all hydraulic elements. The main cooling device is the oil cooler. During the working process, the heat transfer performance of the oil cooler is influenced by such environmental factors as temperature, humidity, dust, wind speed, solar radiation, etc. Among these factors, the ambient temperature has the greatest influence. In this article, the authors formulate a method for calculating the heat transfer performance of an air-cooled oil cooler and use the Matlab-Simulink program to simulate the effect of ambient temperature on the heat transfer performance of an oil cooler, which is the basis for calculating heat transfer and solving the heat balance equation for the entire hydraulic system.