The influence of power on the intensity of working fluid heating in the hydraulic drive

This paper discusses the influence of power on the intensity of working fluid heating in the hydraulic drive. The work considers methods and methods of maintaining thermal conditions in the hydraulic drive. Thermal balance scheme in hydraulic drive of self-propelled machines is considered. Calculation is also made for hydraulic drive of drilling machine. Based on the results of the calculation, a graph was drawn on the dependence of the intensity of pre-start heating of the working fluid on the power developed by the temperature control device.


Introduction
Hydraulic drives play an important role in various industries where efficient and reliable movement of mechanisms is required.However, in order to ensure optimal operation of the hydraulic drive, due attention must be paid to its thermal mode.The thermal mode of the hydraulic drive is a key aspect that affects its reliability, efficiency and durability.
In modern industry, there are many tasks that require high power and continuous operation of hydraulic drives.In such cases, hydraulic drives with a heavy and very heavy operating mode become an integral part of processes where heavy load transfer and complex operations are required.
The design features of the hydraulic system can also affect its climatic mode.For example, the presence of tightly installed pipelines or the absence of an effective cooling system can lead to heating of the working fluid.
The operating mode of the hydraulic drive is also important when considering the thermal mode.Heavy use of the system or prolonged operation at high loads can cause overheating of the working fluid.Therefore, it is necessary to provide sufficient heat exchange power for efficient cooling.
In fact, the preservation of the thermal mode of the hydraulic system includes the analysis of climatic conditions, design conditions and operating modes in order to ensure reliable and efficient operation of the hydraulic drive.
At low temperatures, the hydraulic actuator may encounter problems with the viscosity of the hydraulic fluid, which may increase and result in difficulties in the movement of the hydraulic actuator components.This can lead to loss of efficiency and increased wear of equipment.
However, due to internal heat release, for example, caused by the friction of liquid against the walls of pipelines and hydraulic equipment, the hydraulic drive can be heated and maintain an optimal thermal mode.
Measures, such as the use of insulation or heating elements, may be taken to ensure that the hydraulic drive operates under low temperature conditions in order to maintain the optimum temperature of the fluid and equipment.This prevents freezing of the hydraulic drive and ensures its normal and reliable operation in any climatic conditions.
When determining the total heat flow to the hydraulic drive, power losses associated with fluid friction in various components of the system can be taken into account.This includes loss of liquid friction power in pipelines and hydraulic equipment, as well as loss of friction power in the pump and hydraulic motors.
Fluid friction power losses in piping and hydraulic equipment can be calculated using the Darcy-Weisbach equation, which takes into account pipeline length, diameter, friction factor and fluid flow rate.Taking into account these parameters, you can determine the power that is spent on overcoming friction in the system.
Friction power losses in the pump and hydraulic motors can be determined using their performance characteristics and operating parameters such as fluid flow and pressure.The known friction power losses in these components make it possible to estimate the portion of incoming power that is converted to thermal energy.
In addition, temperature control devices such as heat exchangers or heaters may also provide power to heat hydraulic fluid in the hydraulic actuator.

Materials and methods
Maintaining the thermal mode of the hydraulic drive is an important task to ensure its normal operation and durability.Uncontrolled increase or decrease in temperature can adversely affect the operation of the hydraulic drive and lead to its failure.
The following methods can be used to maintain the optimum thermal mode of the hydraulic drive: -Heat removal; -Heat emission control; -Thermal control.Reliable heat removal system allows efficient removal of heat generated by hydraulic drive.This can be achieved through the use of heat dissipating materials such as radiators or heat exchangers, and through optimizing the design of the system components to improve heat dissipation.
Optimization of the use of hydraulic drive components and minimization of heat release can be achieved through the correct selection of components, taking into account their efficiency and heat transfer, as well as through the installation of measures, for example, reducing friction or using effective lubrication systems.
The use of temperature control devices, such as thermostats or thermocontrollers, makes it possible to maintain an optimal thermal mode of the hydraulic drive.This may include monitoring and maintaining a predetermined temperature of the fluid, coolant, or hydraulic actuator components.
The application of appropriate methods to maintain the thermal mode of the hydraulic drive depends on the peculiarities of the specific system, operating conditions and requirements.
There are several methods of cooling the hydraulic drive: 1. Water cooling -radiators or heat exchangers are used that transfer heat from hydraulic fluid to cooling water.
2. Air cooling -fans are used that remove heat from the hydraulic system through the air cooler.
3. Oil cooling -the cooling oil circulates, which takes heat from the hydraulic fluid through the heat exchanger.
4. Combined method -involves the use of several cooling methods at the same time to ensure optimal heat transfer and maintain a normal hydraulic drive temperature.
The choice of cooling method depends on the size and requirements of the system, the environment and energy efficiency.It is also necessary to take into account the operating conditions and temperature limitations of the hydraulic drive components.

Results and discussion
The external heat source can be heat -electric heaters, energy of removed exhaust gases, etc.
In formula ( 1), the initial temperature Where T0 is the ambient temperature or the temperature to which the car has cooled in degrees Celsius.
Temperature increment during Δτ: Where nag Q( jt     ) -heat used to heat the hydraulic drive: Where -heat obtained by the hydraulic drive during Δτ; -heat transmitted by the hydraulic drive to the environment during Δτ, which will be determined from the equation: Where k is the coefficient of heat transfer from the hydraulic drive to the environment; gp F is the area of the heat-radiating surfaces of the hydraulic drive.
Where nag ( N j t )is the power consumed for heating of the hydraulic drive: nag ( ( ( here ( n Nt ) -power lost in the hydraulic drive (we believe that it is consumed for heating); ( ur N j t )power added to the hydraulic system by the temperature control device.
As practice shows, the heating of the hydraulic drive is carried out until it reaches the optimal thermal mode.Therefore, at t ≥ 0 ºC ( ur N j t )= 0. At lower temperatures, its value is determined by the operation of the control system: In the article, the power of the temperature control device varies from 10 to 60 kW with an interval of 10 kW.
Figure 2 shows the results of calculation on the personal computer of the intensity of working fluid heating in the hydraulic drive of the drilling machine depending on the power of the pre-start heating device.It can be seen from the graphs that without the use of a pre-start heating device, the hydraulic drive will reach the optimal temperature mode only after a long time.However, when using the device, the heating intensity increases sharply, so at power Although the calculation was carried out for a drilling machine with specific parameters, it is possible to apply it to other hydrofined machines, knowing their design and technical characteristics, or designing them.
In this article, the power of the working fluid temperature control device was selected arbitrarily.

Conclusion
Having received data on the required power of the device, its parameters should be calculated and a method for heating the working fluid should be chosen.There are dependencies and formulas for capacity calculation for each method.
The proposed method allows determining the required power of the pre-starter at the stage of designing the hydraulic drive and choosing the most suitable design of the pre-starter and the method of heating the working fluid.

Figure 1 .
Figure 1.Heat balance diagram in the hydraulic drive of self-propelled machines /min.Judging by the above data, with an increase in power, the heating intensity changes slightly after 40 kW and it is advisable to use the power ( ur N j t )= 40 kW, since this is 0.4 of the diesel power and a fairly fast hydraulic drive output to the optimal thermal mode is provided without significant costs.

Figure 2 .
Figure 2. The dependence of the intensity of pre-start heating of the working fluid on the power developed by the temperature control device.