Hitachi 5P cold storage compressor Practical knowledge-advantages and disadvantages of the four compressors
There are many kinds of compressors, commonly used are scroll compressors, piston compressors, centrifugal compressors, screw compressors, etc. I believe everyone does not have a deep understanding of these four compressors. The following Jiaxing Yulong editor and Let's share the advantages and disadvantages of these four compressors, and deepen our understanding of the compressor.
Advantages of scroll compressor: (1) The number of parts is small. (2) Lower vibration and noise. (3) Inhale directly, the inhalation preheat is small, and the volumetric efficiency is higher. (4) More reliable fuel supply. (5) High reliability. (6) Wide operating range. Disadvantages of scroll compressors: (1) The surfaces of moving parts are mostly curved surfaces. The processing and inspection of these curved surfaces are more complicated. Manufacturing requires high-precision processing equipment and precise self-aligning assembly technology, so The manufacturing cost is higher. (2) Between the moving parts or between the moving parts and the fixed parts, a certain movement gap is often used to achieve the seal, and the gas will inevitably cause leakage through the gap, which limits the difficulty of the rotary compressor to reach a larger Compression ratio, therefore, most rotary compressors are mostly used in air conditioners. (3) High sealing requirements and complicated sealing structure.
The advantages of piston compressors: (1) The wide range of applicable pressure of the plug compressor can achieve the required pressure regardless of the flow rate; the piston compressor has high thermal efficiency and low unit power consumption; (2) strong adaptability, Hitachi 101 cold storage compressor, that is, the exhaust range is wide, and it is not affected by the pressure level, and can adapt to a wider pressure range and cooling capacity requirements; (3) the maintainability of the piston compressor is strong; (4) the piston compressor The material requirements are low, more common steel materials are used, the processing is easier, and the cost is lower; (5) The piston compressor is relatively mature in technology and has accumulated rich experience in production and use; (6) The piston compressor device system is relatively simple.
Disadvantages of piston compressors: (1) The speed is not high, the machine is large and heavy; (2) The structure is complex, the wearing parts are many, and the maintenance is large; (3) The exhaust is discontinuous, causing airflow pulsation; (4) Operation Sometimes there is a big shock. The advantages of the centrifugal compressor: (1) The exhaust volume is hit, the exhaust is uniform, and the air flow has no pulse. (2) High speed. (3) The inside of the machine needs lubrication. (4) The sealing effect is good, and there is little leakage. (5) It has a flat performance curve and a wide operating range. (6) Less wearing parts, less maintenance, and long operating cycle. (7) It is easy to realize automation and large-scale. Disadvantages of centrifugal compressors: (1) The adaptability of operation is poor, and the nature of the gas has a greater impact on the operation performance. When the unit starts, stops, and runs, the load changes greatly. (2) The air flow speed is large, and the parts in the flow channel are lost by large friction. (3) There is breathing phenomenon, which is extremely harmful to the machine. The advantages of screw refrigeration compressor: (1) Fewer parts, less wearing parts and high reliability. (2) Convenient operation and maintenance. (3) There is no unbalanced inertial force. The operation is stable and safe, and the vibration is small. (4) It has the characteristics of forced gas transmission, the exhaust volume is almost not affected by the exhaust pressure, and the adaptability of the working conditions is strong. (5) The rotor tooth surface of the screw compressor actually has a gap. Therefore, it is not sensitive to wet stroke and can withstand liquid shock. (6) The exhaust temperature is low, and it can be operated under a higher pressure ratio. (7) Stepless adjustment of refrigeration can be realized, and the spool valve mechanism is adopted, so that the cooling capacity can be steplessly adjusted from 15% to 100%, saving operating costs.
Disadvantages of screw refrigeration compressors: (1) The rotor tooth surface is a space curved surface, which needs special tools to be processed on expensive equipment. The machining accuracy of body parts also has high requirements, and high precision must be used. equipment. (2) Since the interdental volume periodically communicates with the suction and exhaust ports, the compressor noise is high. (3) Due to the limitations of rotor stiffness and bearing life, the compressor can only rely on the gap seal, so the screw compressor can only be used in the medium and low pressure range, and cannot be used in high pressure occasions. (4) Due to the large amount of fuel injection and the complicated oil treatment system, there are many auxiliary equipment of the unit. (5) Screw compressors rely on gap sealing gas, and Hitachi 5P cold storage compressors do not have superior performance in a small volume range. Double-cylinder rotary compressor What is a two-cylinder rotary compressor? In fact, the so-called double-cylinder rotary compressor is also called a double-rotor compressor, which is composed of upper and lower cylinders, and their rotors are symmetrically distributed at 180° to each other. When the gas is compressed, the two cylinders will also maintain The 180° phase difference theoretically proves that the torque change range of the double-cylinder compressor is one-third of the single-cylinder compressor. The torque change of the double-cylinder compressor is also the fundamental cause of vibration, so it can make the compressor The vibration is greatly reduced. And can effectively solve the vibration situation of large rotary compressor.
compressor Why does the compressor frost? In the process of using the compressor, the most common problem of the compressor is the frost of the compressor, so what is the reason for the frost of the compressor? That is, why does the compressor frost? It can be summarized as three reasons: first, the frost of the compressor return port caused by the temperature of the compressor return gas is too low; second, the frost of the compressor return air caused by low fluorine; third, the large amount of wet steam or refrigerant Frost on the compressor cylinder head caused by suction into the compressor. The following editor Jiaxing Yulong and you specifically analyze the cause of compressor frost. First, the compressor return air frost caused by the compressor return gas temperature is too low. So what will cause the compressor return gas temperature to be too low? Refrigerants of the same quality will behave differently if the volume, pressure, and temperature are changed. Hitachi 3p cold storage compressors, that is, liquid refrigerants, if they absorb more heat, the refrigerants of the same quality will exhibit pressure, temperature, and volume. High, the opposite is true if there is less endotherm. Therefore, there are two reasons why the temperature of the compressor return gas is too low: 1. Throttle valve liquid refrigerant supply is normal but the evaporator cannot absorb heat normally and supply refrigerant expansion. 2. The heat absorption of the evaporator works normally but the refrigerant supply (flow rate) of the throttle valve is excessive. It is generally understood that there is too much fluorine, which means that too much fluorine will also cause low pressure. Second, the compressor return air frost caused by low fluorine. There are two reasons for the return air frost of the compressor: 1. The refrigerant flow rate is very small, causing the refrigerant to expand after flowing out of the rear end of the throttle valve. The rapid expansion of some areas due to the small amount of refrigerant causes the local temperature to be too low and frost on the evaporator. Since a heat insulation layer is formed on the surface of the evaporator and the heat exchange amount in this area is low, the refrigerant expansion is transferred to other areas, so the expansion gradually spreads to the compressor return air pipe and causes the compressor return air to frost. 2. The amount of refrigerant is too small. The low evaporation pressure of the evaporator leads to low evaporation temperature. It also gradually causes the condensation of the evaporator to form an insulating layer, and the expansion point is transferred to the compressor return air to cause frost on the compressor return air. Third, a large amount of wet steam or refrigerant sucked into the compressor causes frost on the compressor cylinder head. The causes of frost on the compressor cylinder head are as follows: 1. The opening of the thermal expansion valve is too large, the temperature sensor is installed incorrectly or the fixing is loose, so that the temperature is too high and the valve core is opened abnormally. 2. The liquid supply solenoid valve leaks or the expansion valve is not closed tightly during shutdown, causing a large amount of refrigerant liquid to accumulate in the evaporator before starting. The temperature relay is used in conjunction with the solenoid valve to control the warehouse temperature. 3. When the compressor is started, the opening of the suction cut-off valve is too large or opened too early. 4.There is too much refrigerant in the system, the pressure in front of the expansion valve increases, the amount of refrigerant flowing into the evaporator increases, the liquid refrigerant cannot fully evaporate in the evaporator, the compressor will suck in wet steam, causing the cylinder to become cold or even Frosting may cause "liquid strike" and the evaporation pressure will be high.
