Research on the integrated technology of "efficient cooling and Purification" of hydraulic system

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【Summary】For hydraulic and lubrication systems, oil overheating and contamination is an important cause of mechanical equipment failure. The fault of hydraulic system caused by pollution has been gradually recognized, but the harm of excessive oil temperature has not been paid enough attention. The total efficiency of the hydraulic system is usually only 50%~70%, so "high fever" is one of the common problems of the hydraulic system.

For hydraulic and lubrication systems, oil overheating and contamination is an important cause of mechanical equipment failure. The fault of hydraulic system caused by pollution has been gradually recognized, but the harm of excessive oil temperature has not been paid enough attention. The total efficiency of the hydraulic system is usually only 50%~70%, so "high fever" is one of the common problems of the hydraulic system.

Excessive oil temperature in hydraulic system will cause many harms. For example, oil viscosity will decrease, system volume efficiency will decrease, temperature rise will be aggravated, and a vicious cycle will be created. Reduce the strength of sealing ring, and promote the aging of rubber, reduce the reliability of the machine; Accelerate oil oxidation and shorten service life.

Therefore, the research of strengthening heat transfer technology and efficient purification technology, the development of small volume, high efficiency, can simultaneously reduce the oil temperature purification system cooling purification products to improve the reliability of the hydraulic system, lubrication system and the service life of mechanical equipment has a general significance.

Experimental study on flow and enhanced heat transfer in tube - shell heat exchanger

For oil cooling tube and shell heat exchanger, the widespread use of shell side flow heat transfer is a weak link for many years, the shell side strengthening heat transfer of the most common method is to add ribs on the outside of the pipe, to increase the shell side of heat exchange area of progress in order to restrict the flow of fluid to strengthen shell heat exchanger, people use a variety of block flow board to enhance the heat transfer, use morer is e. straight cover panels or bow. They make the flow of the medium on the shell side cross the tube bundle, make the fluid mix strengthened locally and the turbulence deepened, and fully contact with the tube wall, so as to realize the enhancement of heat transfer.

Gupta et al. used a tracer ball to show the shell flow on ILUS, a small glass-made heat exchanger. Berner observed the flow of fluid through the baffle plate by injecting tracer fluid into the plexiglass case and using aluminum tracer ball. Murray observed the flow pattern through the bundle by injecting tracer fluid and tested the flow resistance.

Experimental study on flow pattern display

The flow pattern display experiment shows that the tracer fluid forms an obvious relative eddy current stagnation zone near the straight baffle plate, which is not conducive to the heat exchange spiral plate to eliminate the eddy current stagnation zone, extend the flow of the fluid and enhance the heat transfer. The addition of porous media to the spiral plate flow channel has a great disturbance to the flow and a turbulent flow is formed at a very low Reynolds number.

Resistance test results

The pressure difference between inlet and outlet is measured under different flow rates and the resistance characteristics are studied.

Gauge, spiral Angle. When is 3045, the pressure drop is the smallest, which is obviously the best helical plate Angle. The amount of porous media filled in the spiral plate flow passage is defined by the total volume of porous media volume of the porosity flow passage. The decrease in the total volume of porous media volume of the flow passage is not large, but the pressure drop increases sharply when the porosity is 0.977. Can be, the porosity of filling porous media in the spiral plate runner is. The 985 drill makes more sense

(3) Experimental study on heat transfer performance of tubular heat exchanger

From five different shell side of the structure of the heat transfer performance test results (see), the heat transfer effects from high to low in turn order for spiral plate, spiral Angle U = 40 * add porous medium () = 0.985), spiral plate (U = 40 * straight block flow plate (plate spacing S = 50 mm), straight blocked flow board (S = 100 mm) and porous medium (= 0.985), plant a Reynolds number/fe 2 high gradient magnetic filtration technology research field of the attraction of the ferromagnetic particles is the decisive factor, the performance of magnetic filter pollution particles in magnetic field, the stress of the conductivity, H/m. X*, is the permeability of oil, H/m; H is the strength of external magnetic field, A/m; GradH is the gradient of the external magnetic field intensity at this point, A/m2. It can be seen from Equation (1) that the attraction force on ferromagnetic particles is in direct proportion to the external magnetic field intensity H, which is in direct proportion to the magnetic field intensity gradient gradH. Conventional magnetic filters all improve the magnetic attraction by increasing the external magnetic field intensity H, thus improving the filtration capacity. High gradient magnetic filter is to increase the attraction by means of magnetic medium, mainly improving the gradient gradH of magnetic field to obtain the effect of efficient filtration of pollutants. The arrangement of polymagnetic porous media in magnetic field will make the magnetic field H and magnetic field gradient gradH near magnetic medium much larger than that without magnetic medium.

Especially gradH is inversely proportional to the magnetic medium section diameter d, when d is very small, gradH values can be very high so based on the principle of magnetic filter, also known as efficient heat transfer enhancement high gradient magnetic filter 3 porous medium and high gradient magnetic purification integration compatibility and mutual combination of heat transfer enhancement porous medium and high gradient magnetic purification technology, porous medium can significantly increase the flow of oil flow disturbance, destroy the boundary layer, enhanced heat transfer; At the same time, the porous medium can greatly improve the magnetic field gradient, thus improve the performance of magnetic filter, shows that it has good compatibility with the reciprocity of the combination also performance in controlling the temperature on the influence of the permanent magnet and rough heat exchange surface 1 lower the temperature of the permanent magnet, two aspects to improve the efficiency of the high gradient magnetic purification considering the reliability of the work, the hydraulic lubrication system of the magnetic source with permanent magnets, magnetic purification high gradient magnetic filter, filter oil temperature of hydraulic system of permanent magnet and the same at different temperatures, the performance of the permanent magnet has certain change, will have a significant impact on the efficiency of magnetic filter.

The magnetic properties of permanent magnets are affected by environmental factors such as temperature, time and stress, among which temperature is the most important one. Obviously, the effect of temperature must be taken into account when studying the performance of magnetic filters.

1. To have developed a processing gear oil with high viscosity of high gradient magnetic filter shell when he worked in different temperature boundary condition of the magnetic field tested, the results showed that 18 ℃ 70 ℃ when the magnetic field strength is only a quarter of the left and right sides, as shown in the test did not consider the factor of heat preservation time, but is enough to prove that the high gradient magnetic field of magnetic filter affected by temperature significantly

2. The relationship between magnetic field strength and temperature of high-gradient magnetic filter can realize the integration of cooling and purification. Permanent magnets can be placed in the cooling medium to keep the magnet low temperature and maintain the magnet high magnetism, thus improving the efficiency of high-gradient magnetic purification.

3. The rough surface of heat exchange, improve the thermal efficiency in magnetic purification capture particles of iron wear more, the arrangement of the magnet in the cooling water pipe, some particles must be adsorbed on the outer surface of the cooling water pipe, in the heat transfer on the surface of the particles can have the effect of heat transfer surface roughness, prevent the formation of the boundary layer, to further improve the heat transfer efficiency to take out the cooling pipe of a permanent magnet, pollution particles lose adsorbability, can easily realize the erase

The development and performance test of the shell and tube cooling purifier are combined with the heat transfer enhancement technology of porous media and high-gradient magnetic purification technology to develop the shell and tube cooling purifier. The structure diagram shows that the polymagnetic porous media is a thin filament of 0.04mm thick and 0.5mm wide sprayed from amorphous soft magnetic alloy. Other Uighur pieces are made of stainless steel, to avoid the shadow of the magnetic field ground by permanent magnet arrangement in the center of the pipe and tube, the same polar surface relative to the magnetic field lines extending outward, fully magnetized polymer in porous media center tube magnetic magnets and wall allows the cracks in the cooling water flow, make the center pipe and the pipe, at the same time make a permanent magnet cooling filter performance experiments showed that under the condition of same traditional magnetic filter for 1 (filtering ratio is only 1.38 Mm or more particles, the appropriate filter efficiency of 27% and the newly developed tube shell type cooling purifier to 1 (Mm particle filtration efficiency of 84% above, It can be seen that the filtering efficiency of the cooling purifier is 2.1 times higher than that of the traditional magnetic filter. The comparison between the convection heat transfer coefficient of the shell side of the newly developed tubular cooling purifier and the existing products shows that the performance of the cooling purifier is compared with SL307 oil coolers and TSO306 oil coolers. At the Reynolds number of 2000, the convective heat transfer coefficient at the shell side of the cooling purifier was 19.7* higher than SL307 and 3% higher than TS306.

Significance and method of hydraulic system flushing

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Significance and method of hydraulic system flushing

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Elimination of abnormal oil temperature

　　The magnetic field at the center of the end face of the housing when a high-gradient magnetic filter developed to handle high-viscosity gear oil is operated at different temperatures is tested. The results show that the magnetic field strength at 70℃ is only about 1/4 of 18℃. See that this test does not consider the holding time factor, but it is enough to prove that the magnetic field of the high gradient magnetic filter is significantly affected by the temperature

Significance and method of hydraulic system flushing

From the perspective of use, the first condition for the normal operation of the hydraulic system is that the inside of the system must be clean. Before the operation of new equipment, or after a piece of equipment has undergone major repairs, contamination of the hydraulic system is inevitable. It is possible to bring contaminants into the system during the installation of hoses, pipes and fittings. Even new oils will contain some unexpected contaminants.

Research on the integrated technology of "efficient cooling and Purification" of hydraulic system