In the production work of various industries, the commonly used chillers are air-cooled chillers or water-cooled chillers. These two types of chillers are the most common in the market.
Air-cooled and water-cooled industrial-grade chillers are critical for industrial processes, such as plastics, pharmaceuticals, commercial printing, and transportation manufacturing. Our clients also rely on them for brewing processes, dairy farm operations, and medical equipment processing.
Both air-cooled and water-cooled chillers work by removing the heat from your processes so that your equipment stays cool, so they can keep running strong. In this post, we’re providing an insider look at the main components of a process chiller and the importance of each one.
If you’ve ever wondered what’s inside a chiller, here are the four main components of both air-cooled and water-cooled process chillers to know about the 4main components of chillers and basic working principles of a water chiller.
1.The First Important Part is Compressor of chiller.
The main engine of chiller cold compressor is screw and centrifugal compressor, and the commercial engine is scroll compressor.
In the refrigeration industry, common compressors can be divided into the following categories.
Rotor compressor is a positive-displacement rotary gas compressor. The compression volume is defined by the trochoidally rotating rotor mounted on an eccentric drive shaft with a typical 80 to 85% adiabatic efficiency.
Piston Compressor is a positive-displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure.
Screw compressor is a type of gas compressor, such as an air compressor, that uses a rotary-type positive-displacement mechanism. These compressors are common in industrial applications and replace more traditional piston compressors where larger volumes of compressed gas are needed, e.g. for large refrigeration cycles such as chillers, or for compressed air systems to operate air-driven tools such as jackhammers and impact wrenches.
4)Magnetic Suspension Centrifugal Compressor
Magnetic suspension centrifugal compressor is discharged from the air conditioner compressor through high temperature and high pressure freon, enters the condenser, releases heat to the copper tube cooling water, condenses into medium temperature and high pressure Freon liquid, and then depressurizes to low temperature and low pressure liquid through the shut-off valve, enters the evaporator, absorbs heat from the frozen water flowing through the copper tube in the evaporator shell, gasifies into low temperature and low pressure gas, and then inhales into the compressor, which is used in the compressor Through this cycle, the purpose of cooling is achieved.
2.The Second Important part is the Evaporator.
Evaporator of industrial chiller
Ordinary, there are 3 kinds of Evaporator we would use: Dry Evaporator / Full liquid Evaporator / Fall Film Evaporator
The working principle is the refrigerant flows in the tube and the water flows outside the tube cluster. Generally, the problem of oil accumulation does not exist when the lubricating oil from the shell enters the compressor with the refrigerant.
The dry evaporator is mainly composed of heat transfer tube, stripper, water discharge tube, refrigerant inlet tube, refrigerant outlet tube, refrigerant water inlet tube, refrigerant water outlet tube, left and right end caps and shell.
the Characteristic of dry Evaporator:
1.The heat transfer coefficient is high and the temperature difference is small;
2.The amount of refrigerant filled is less, generally only about 1 / 3 of that of full liquid type;
3.When the temperature is near 0 ℃, the water will not freeze, the heat transfer coefficient is 4.low and the temperature difference at the end is large;
5.Scale is easy to pay on the surface of evaporator copper tube, and is not easy to clean;
2)Full liquid evaporator
The refrigerant flows outside the pipe and the water flows inside the pipe. It is composed of shell, evaporation tube (high efficiency tube), tube sheet, support plate, etc.
the Characteristic of Full Liquid Evaporator:
1.The heat transfer coefficient is high and the temperature difference is small;
2.The water goes through the pipe and is easy to clean;
3.The refrigerant liquid basically fills the tube bundle, and the charge quantity is large;
4.The return oil of full liquid evaporator is difficult and unstable;
5.When the evaporation temperature of refrigeration system is lower than 0 ℃;
6.The water in the tube is easy to freeze and destroy the evaporation tube;
7.The static liquid column of the liquid in the full liquid evaporator increases the saturated evaporation temperature at the bottom.
3)Falling film evaporator
The refrigerant is evenly separated from the distributor, forms a liquid film on the surface of the heat exchange tube, absorbs the heat in the tube and evaporates, and water flows in the tube, which is composed of distributor, shell, evaporation tube (high efficiency tube), tube sheet, support plate, etc.
the Characteristic of Falling Film Evaporator:
1.High heat transfer coefficient and small end temperature difference (better than full liquid, better than dry type);
2.The lubricating oil accumulates at the bottom of the container and is easy to return due to its high concentration;
3.Avoid the liquid column in the full liquid evaporator to increase the saturated evaporation temperature at the bottom;
4.The main pipe phenomenon of falling film is avoided, the heat transfer is more uniform and the efficiency is higher;
5.The water goes through the pipe and is easy to clean;
6.When the evaporation temperature of refrigeration system is lower than 0 ℃, the water in the tube is easy to freeze and destroy the evaporation tube.
3.The Third Main part is Condenser of chiller
It is a part of refrigeration system, belonging to a kind of heat exchanger, which can convert gas or steam into liquid and transfer the heat in the pipe to the air near the pipe in a very fast way. The condenser is a heat releasing device, which transfers the heat absorbed in the evaporator together with the heat converted by the compressor work to the cooling medium. The working process of condenser is an exothermic process, so the temperature of condenser is higher.
It is composed of built-in separator, shell, evaporation tube (high efficiency tube), tube sheet, support plate, subcooler, etc.
According to the different cooling medium, condensers can be divided into three types: water cooling type, air cooling type and evaporation type.
1)Water cooled condenser
Water cooled condenser takes water as cooling medium and takes away condensation heat by the temperature rise of water. The cooling water is generally recycled, but the cooling tower or cool pool should be set in the system. According to its structure, water-cooled condenser can be divided into shell and tube condenser and tube and tube condenser.
a.Vertical shell and tube condenser
The main features are as follows:
1) Because of the large cooling flow and high flow rate, the heat transfer coefficient is high.
2) Vertical installation covers a small area and can be installed outdoors.
3) The cooling water flows directly and the flow rate is large, so the requirement of water quality is not high. Generally, the common water can be used as cooling water.
4) The scale in the pipe is easy to clean, and it is not necessary to stop the refrigeration system.
5) The temperature rise of the cooling water in the vertical condenser is generally only 2-4 ℃, and the logarithmic average temperature difference is generally about 5-6 ℃, so the water consumption is large. And because the equipment is placed in the air, the pipe is easy to be corroded, and the leakage is easy to be found.
b.Horizontal shell and tube condenser
It has the similar shell structure with the vertical condenser, the main difference lies in the horizontal placement of the shell and the multi-channel flow of water.
Horizontal condenser is widely used in refrigeration system and freon refrigeration system, but its structure is slightly different. According to the horizontal condenser, the cooling tube is smooth seamless tube, while the cooling tube of Freon horizontal condenser is generally low rib copper tube.
This is due to the low exothermic coefficient of Freon. It is worth noting that some freon refrigeration units generally do not have liquid storage tanks. But only use a few rows of tubes at the bottom of the condenser, which is also used as a liquid storage tank.
The vapor of the refrigerant enters the cavity between the inner and outer tubes from above, condenses on the outer surface of the inner tube, and the liquid flows down at the bottom of the outer tube in turn, and flows into the liquid reservoir from the lower end.
The cooling water enters from the lower part of the condenser and flows out from the upper part of the condenser through the inner tubes of each row in turn. This kind of condenser has the advantages of simple structure, easy manufacture, and good heat transfer effect because of single tube condensation and opposite medium flow direction.
Its disadvantage is that the metal consumption is large, and when the number of longitudinal tubes is large, the lower tube is filled with more liquid, so that the heat transfer area can not be fully utilized.
In addition, the compactness is poor, the cleaning is difficult, and a large number of connecting elbows are needed. Therefore, this kind of condenser has been rarely used in refrigeration device. Casing condenser is still widely used in small Freon air conditioning units.
d. Air cooled condenser
Air cooled condenser takes air as cooling medium and takes away condensation heat by air temperature rise. This kind of condenser is suitable for the situation of extreme lack of water or water supply, and is commonly used in small freon refrigeration units. According to the different ways of air flow, it can be divided into natural convection and forced convection.
e. Evaporative condenser
The heat transfer of evaporative condenser mainly depends on the evaporation of cooling water in the air to absorb the latent heat of gasification. According to the way of air flow, it can be divided into suction type and pressure type.
The evaporative condenser is composed of cooling pipe group, water supply equipment, fan, water baffle and box. The cooling pipe group is a snake coil group made of seamless pipe bending, which is installed in a rectangular box made of thin steel plate. The two sides or top of the box body are provided with ventilators, and the bottom of the box body is also used as a cooling water circulating pool.
Parallel connection of evaporative condenser and shell and tube condenser:
4.The Forth Important part is Throttling Device
Throttling device of chiller
The main function is to throttle and depressurize, control and regulate the refrigerant flow and superheat.
Double orifice plate: slow adjustment response; almost no adjustment ability; small energy adjustment range; low cost.
Electronic expansion valve: simple structure, small resistance, wide energy regulation, rapid response to energy efficiency regulation, high cost.
Pro tip: For low-temperature requirements, ask about electronic expansion valves (EEVs) to give you tight superheat control. They work by using a stepper motor that precisely regulates the valve’s position.
Each of these components of industrial-grade process chillers serves a vital role in cooling your equipment.