Water chillers are divided into air-cooled chillers and water-cooled chillers in the industry. The temperature control of chillers is divided into low-temperature chillers and normal temperature chillers. Normal temperature temperature is generally controlled within the range of 0 degrees to 35 degrees. The temperature control of the cryostat is generally in the range of 0 degrees-minus 100 degrees.
The chiller is a kind of water cooling equipment, and the chiller is a kind of cooling water equipment that can provide constant temperature, constant flow and constant pressure.
Working principle of chiller
Inject a certain amount of water into the water tank in the machine in advance, cool the water through the chiller refrigeration system, and then send the low-temperature cooling water to the equipment that needs to be cooled by the water pump, the chiller chilled water will take away the heat and the temperature will rise before returning to the water tank , To achieve the cooling effect.
Use air conditioning
In air conditioning systems, chilled water is usually allocated to heat exchangers, or coils in air handling units, or other types of terminal equipment that are cooled in their respective spaces (S air), and then the cooling water is redistributed back to the cooling to be cooled. . These cooling coils transfer sensible and latent heat from the air to the chilled water, so the cooling air stream is usually dehumidified. A typical air conditioning unit is rated for 15 to 1500 tons (180,000 to 18,000,000 British thermal units/h or 53 to 5,300 kilowatts) of cooling capacity. The chilled water temperature ranges from 35 to 45 degrees Fahrenheit or 1.5 to 7 degrees Celsius, depending on the application requirements.
When the chiller refrigerant cycle system, the liquid refrigerant in the evaporator absorbs heat from the water and starts to evaporate. A certain temperature difference is formed between the final refrigerant and the water. The liquid refrigerant is also completely evaporated and becomes gaseous and then sucked by the compressor. Compression, the gaseous refrigerant absorbs heat through the condenser, condenses into liquid, throttling through the thermal expansion valve, and turns into a low temperature and low pressure refrigerant to enter the evaporator, completing the refrigerant cycle process.
When the chiller is forming products, due to the variety of raw materials, the size and shape of the molded product, the required clamping force is different. When adjusting the mold, please adjust according to the minimum clamping force actually required. In this way, power consumption can be saved and the service life of the machine can be significantly extended.
When using the industrial water chiller, you must pay attention to the safety of the operation. Please check the safety device of the machine, the reliability of the safety top rod and the safety door at the beginning of each operation. When the machine is running, remember not to reach into the clamping mechanism. When taking products, the safety door must be opened, and the safety door can only be closed after confirming the safety of personnel and no foreign objects in the mold. In addition, the hand cannot reach between the nozzle and the mold gate during operation. When repairing the mold, turn off the oil pump motor.
Screw chiller has the advantages of high efficiency, good performance, low noise, low vibration, energy saving, high reliability and long life. According to customer needs and the size of the cold tonnage, a single machine or a combination of multiple machines is used. The compressor can automatically rotate alternately according to load changes, balance the operating hours of each compressor, and greatly extend the service life of the chiller. Use industry 1. Selection of the model size of the special chiller for injection molding machine. When used for cooling the mold of the injection molding machine, a 25HP chiller is needed. When used for cooling of other equipment, it depends on the specific flow rate of the cooling water circulation. 2. The selection of the heat preservation water tank and pump of the chiller is sometimes based on the actual situation of the customer's factory. When the open chiller is connected to the external pump, the pump power requirements are the same as the requirements of the box chiller of the same model. 3. The temperature of the return water of the chiller should not be higher than 40 degrees. The higher the return water temperature, the greater the damage to the compressor.
In industrial applications, chilled water or other liquid cooling pumps are passed through processes or laboratory equipment. Industrial chillers are used in various industries to control the cooling of products, mechanisms and factory machinery. They are commonly used in injection and blow molding in the plastics industry, metal processing cutting oils, welding equipment, die casting and machining, chemical processing, pharmaceutical formulation, food and beverage processing, papermaking, cement processing, vacuum systems, X-ray diffraction, electric power Supply and power stations, analytical equipment, semiconductors, compressed air and gas cooling. They are also used to cool high thermal energy, such as MRI machines and laser specialized engineering projects, and in hospitals, hotels and campuses. The chillers for industrial applications can be centralized, and each chiller can meet multiple needs for cooling, or be dispersed in each application or device with its own chiller. Each method has its advantages. It may also have a combination of central and decentralized chillers, especially when the cooling requirements are the same for certain applications or use points, but not all.
Distributed chillers have a small area (cooling capacity) usually from 0.2 tons to 10 tons. Central chillers generally have a capacity ranging from 10 tons to hundreds or thousands of tons.
Chilled water is used to cool and dehumidify the air in large-scale commercial, industrial and institutional alliance (CII) facilities. The chiller can be water-cooled, air-cooled, cooled or evaporatively. The use of water-cooled chillers is incorporated into cooling towers, which improves the cooling' thermodynamic efficiency compared to air-cooled chillers. This is due to the high temperature or wet bulb temperature of the nearby air, rather than repelling the high, sometimes much higher dry bulb temperature. Evaporatively chillers provide better efficiency than air cooling, but lower than cold water.
Several aspects of the chiller:
1. Selection of model size of chiller for injection molding machine
When used as a mold cooling of an injection molding machine, it can be calculated according to the injection volume of the injection molding machine. Generally, a 1HP water chiller is required for every 6 ounces of injection volume. For example: The customer’s factory is 100T (5.5OZS)×3; 150T(12OZS)×4 units; 200T(23OZS)×3 units; the required chiller size is (5.5×3+12×4+23×3)/6=22.25, that is, a 25HP chiller. When used for cooling of other equipment, it depends on the specific flow rate of the cooling water circulation.
2. Selection of the insulation water tank and pump of the chiller
Sometimes according to the actual situation of the customer's factory, the box-type chiller may also require an external pump. At this time, the additional pump model must have the same power as the pump that comes with the chiller. If the 10HP box-type chiller comes with a pump power of 2HP, when the pump is added, it must also be 2HP.
At the time of , the power requirement of the water pump is the same as that of the box-type chiller of the same model. The open chiller is connected to the external water pump.
3. The return water temperature of the chiller should not be higher than 40 degrees. The higher the return water temperature, the greater the damage to the compressor.
The methylene lithium bromide solution is collected at the bottom of the absorption shell. From here, a sealed solution is a solution for preheating through a mobile pump shell and tube heat exchanger.
After the generator exits, the heat exchanger dilutes to the action of the upper shell solution. The solution revolves around bundled pipes for any steam or hot water. The steam or hot water transfers heat to the dilute lithium bromide solution pool. The solution to boils, the refrigerant vapor sent into the condenser is concentrated upwards and the lithium bromide leaves behind. The concentrated lithium bromide solution moves down the heat exchanger, where it is pumped from the weak solution to the generator for cooling.
The refrigerant vapor through the mist eliminator migrates to the condenser tube bundle. The refrigerant vapor on the pipe condenses. The removed heat moves through the tube through the cooling water. As the refrigerant is concentrated, it collects in the trough at the bottom of the condenser.
The hydraulic refrigerant flows from the upstream shell down to the downstream shell condenser and evaporator, and the evaporator is sprayed in the tube bundle. Due to the extreme vacuum of the low shell [6 mmHg (0.8 kPa) absolute pressure], the refrigerant liquid has a boiling point of approximately 39°F (3.9°C), creating a cooling effect.
Shock absorber migration
As the refrigerant vapor is absorbed by the evaporator, the powerful lithium bromide solution from the generator is sprayed over the entire absorption tube bundle. The strong lithium bromide solution actually drives into the solution refrigerant vapor, causing an extreme vacuum in the evaporator. The heat generated in the lithium bromide solution is absorbed by the cooling water to remove the refrigerant vapor. The dilute lithium bromide solution is collected in the lower shell, where it flows to the bottom of the solution pump. The chilling cycle is complete, and the process begins again.
Vapor compression refrigeration uses the internal refrigerant as its working fluid. There are many choices of refrigerants, but when choosing a cooler, the application requirements of the cooling temperature match the refrigeration characteristics of the refrigerant. The important parameters to consider are operating temperature and pressure.
There are several environmental factors concerned about the refrigerant, which also affect the future availability of the unit's application. This is an intermittent application mainly considering that large chillers may last more than 25 years. Ozone depletion potential (ODP) and global warming potential (GWP) refrigerants need to be considered. Potential and some of the more common water vapor data compression refrigerants:
The operation of the chiller system is through three interrelated systems: refrigerant circulation system, water circulation system, and electrical automatic control system.
Compressor: The compressor is the core component of the entire refrigeration system and the source of power for refrigerant compression. Its function is to convert the input electrical energy into mechanical energy and compress the refrigerant.
Refrigerant circulation system of chiller:
The liquid refrigerant in the evaporator absorbs the heat in the water and starts to evaporate. Eventually, a certain temperature difference is formed between the refrigerant and the water. The liquid refrigerant is also completely evaporated and becomes gaseous and then sucked by the compressor and compressed (pressure and temperature increase) , The gaseous refrigerant absorbs heat through the condenser (air-cooled/water-cooled), condenses into a liquid, and is throttled by a thermal expansion valve (or capillary tube) to become a low-temperature and low-pressure refrigerant to enter the evaporator, completing the refrigerant cycle process.
As the wind condenser pays special attention to its own cleanliness, if it accumulates dust, it will not only affect the heat dissipation effect, reduce the cooling capacity, but also affect the increase of the shaft power, which is very easy to damage the compressor, so it must be noted: regular cleaning of the condenser, (please follow It is recommended to use a high-pressure air gun to blow once a week, and rinse with clean water every three months if necessary.
After the compressor has been running for 1,000 hours, check it: 1. Whether the lubricating oil is normal; 2. Whether the current is normal when the compressor is running; 3. Whether there is any abnormal sound when the compressor is running.
Scope of application
Plastic industry: Accurately control the mold temperature of various plastic processing, shorten the plastic molding cycle, and ensure the stability of product quality.
Electronics industry: Stabilize the molecular structure of electronic components on the production line, improve the qualification rate of electronic components, and apply it to the ultrasonic cleaning industry to effectively prevent the volatilization of expensive cleaning agents and the damage caused by volatilization.
Electroplating industry: control the plating temperature, increase the density and smoothness of plating parts, shorten the plating cycle, increase production efficiency, and improve product quality.
Machinery industry: control the oil temperature of the oil pressure system, stabilize the oil temperature and oil pressure, extend the oil quality use time, improve the efficiency of mechanical lubrication, and reduce wear.
Construction industry: supply chilled water for concrete, make the molecular structure of concrete suitable for construction purposes, and effectively enhance the hardness and toughness of concrete.
Vacuum coating: control the temperature of the vacuum coating machine to ensure the high quality of the coated parts.
Food industry: used for high-speed cooling after food processing to adapt to packaging requirements. There is also control of the temperature of fermented foods.
Pharmaceutical industry: In the pharmaceutical industry, it is mainly used to control the temperature control of fermented drugs. Pharmaceutical companies should make full use of chiller equipment, continue to strengthen technological innovation based on their advantages, and enhance the cost-effectiveness of chillers, so as to better serve the pharmaceutical sector.
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