The refrigeration system is a complex system with multi-variable and large inertia and pure lag. How to make the system effectively and quickly enter the specified working conditions and keep the system stable within the scope of the national standard is a solution to the automatic test of compressor refrigeration capacity. Difficulties are also a hot spot in the research of refrigeration industry at home and abroad. The domestic research on the automatic test of compressor refrigeration has been going on for a long time, but there are many theoretical and simulation analyses. The actual successful application is less, mainly because the physical process of the refrigeration system is quite complex, with time-varying nonlinear randomness and large Hysteresis, it is quite difficult to accurately establish the dynamic model of the whole system, which brings problems to the stable control of the system. The development of the compressor test system, one of the first tasks is to achieve high-precision control of the national standard working conditions, the instability of control has led to the need to manually participate in the regulation of the system developed in China. Therefore, the development of fully automatic and high-precision cooling capacity test bench must overcome the above difficulties, and carry out algorithm innovation and improvement.
The mathematical model between the main parameters of the cold system, so the traditional method of establishing the control algorithm based on the mathematical model is not ideal. Therefore, the traditional temperature and pressure PI control algorithm is improved, and the intelligent PI strategy is proposed and introduced. The prediction mechanism compensation method enables the system to quickly approach the specified conditions. The national standard conditions mainly regulate the condensing temperature and the supercooling temperature of the evaporating temperature, and the temperature specified by the national standard is determined by the suction pressure of the suction pressure and the temperature of the expansion valve before the actual system. The electronic expansion valve heater and the two water quantity regulating valves are respectively controlled by the hysteresis control amount, and in the actual process of debugging, the change of the suction temperature is mostly independent of the change of another controlled quantity, inhaling. The change of temperature also affects other variables, so the control of the inspiratory temperature is controlled by an independent intelligent PI control algorithm, while the control of other variables is controlled by an intelligent control algorithm with a predictive mechanism.
Iron-based alloy powder is commonly used in plasma transfer arc welding (PTAW) due to its excellent mechanical properties and high resistance to corrosion and heat. This type of powder is typically composed of iron as the base metal, along with various alloying elements such as nickel, chromium, molybdenum, and tungsten.
The specific composition of the iron-based alloy powder may vary depending on the desired properties and application requirements. For example, adding nickel can increase the strength and toughness of the weld, while chromium enhances the corrosion resistance. Molybdenum and tungsten are often added to improve the high-temperature strength and creep resistance of the weld.
Iron-based alloy powders for PTAW are available in various particle sizes, typically ranging from a few micrometers to several hundred micrometers. The powder is usually fed into the plasma arc through a powder feeder, which ensures a controlled and consistent supply of powder during the welding process.
During PTAW, the powder is melted and deposited onto the workpiece, forming a weld bead. The high energy plasma arc provides the heat necessary to melt the powder and the base metal, creating a strong and durable weld joint.
Overall, iron-based alloy powder for plasma transfer arc welding offers excellent weldability, high mechanical properties, and resistance to corrosion and heat, making it suitable for a wide range of applications in industries such as aerospace, automotive, and power generation.
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