One of the most common questions that is repeated between building builders, consulting engineers, and project installation executives when deciding and choosing the type of chiller in the air conditioning system of any project is the choice between scroll and screw chillers, which usually have different opinions.
But the fact is that each of these choices has advantages and disadvantages, and according to the project specifications, the device installation location, the type of use, and even the dimensions of the project, it is necessary to consider the optimal mode for each project by experts and engineers, and the most suitable ventilation system Air conditioner and chiller should be selected for it.
In fact, none of these two choices is preferable to the other without default! In order to make the matter more open, at first, we briefly provide explanations about each of these two types of chiller compressors and finally summarize it.
Chiller with scroll compressor
This type of compression chiller is checked regardless of the type of condenser, air-cooled or water-cooled.
Scroll compressors perform the refrigerant compression by two non-coaxial spirals, and their function is that the gas enters this spiral, and the rotation of this spiral (due to non-coaxial) causes the refrigerant gas to condense between the walls. Finally, the condensed refrigerant gas exits from the center of those spirals.
These compressors are less noisy, and the gas flow in them is continuous, unlike piston compressors. Also, these compressors have a more reasonable price, but they are produced in small sizes. Scroll chillers are made from the minimum capacity, which is usually two tons of refrigeration, and are usually used up to 150 tons. High efficiency at full load is one of the advantages of these compressors, although problems such as non-repairability and single-stage operation are disadvantages of this compressor.
To make these types of chillers, manufacturers use more compressors so that they can have better capacity control. This will increase the number of refrigeration and electrical parts, but since the other parts are smaller, it does not have a significant impact on the final price.
Chiller with screw compressor
Compared to the scroll compressor, the screw compressor is more industrial, has higher dimensions and capacity, and is repairable. Also, the price of these compressors is higher. The basis of the work of this compressor is by using one or more spirals, the volume between their ribs decreases from the beginning to the end, and finally, with the entry of low-pressure refrigerant gas and the rotation of the spiral and its movement, it gradually condenses and finally the refrigerant It comes out as a dense gas from its end.
In these compressors, the flow of gas is continuous, but the sound produced is more. One of the very good advantages of this compressor is the possibility of non-step capacity control, which is provided by changing the place of gas entry into the spiral during a complex process.
These chillers are usually produced from a capacity of 30 tons to a capacity of about 500 refrigeration units. The full load efficiency of these compressors is approximately the same as that of scrolls and a little less than them, but partial ones have a high efficiency between 50 and 70 percent, which is less important. Is.
Now we choose between these two types of chillers
One of the ways to choose between the two is the capacity of the device. If the tonnage of the compression chiller we want is less than 60 tons of refrigeration, we will choose a chiller with a scroll compressor, and if the chiller capacity is higher than 150 tons, the screw chiller will be a better option, except in special design conditions.
Therefore, most research is related to capacities between 60 and 150 tons, which includes a wide range of buildings, According to the classification of buildings in the following way, we can have a somewhat better choice.
Chiller with screw compressor
Residential complexes with a large number of small units (economical)
The recommended option is the screw chiller because in these buildings it is very possible to install a small Darbar chiller. Also, residential buildings are used 24 hours a day. As we know, at night, due to the decrease in ambient temperature, the compressor is out of full load mode, which increases It will bring the efficiency of screw chillers.
The building of commercial and entertainment centers
In commercial and entertainment centers, the need for partial load is usually less due to the fact that they work fewer hours than residential buildings and the entire space is occupied at the same time in summers with hot weather.
Also, the sound produced by the chiller compressor in the engine room of the commercial and recreational complex is not very important, so in such projects, there is not much difference between scroll and screw, and considering the lower price and sound of the scroll compressor, the installation location and the buyer's budget, the decision is yours.
Office buildings
Choosing the type of chiller for office buildings is similar to commercial centers, and the partial load and power difference in different hours are less. The use is for several hours a day, and again, the decision is made according to the budget and the importance of the sound and vibration of the device with the respected expert of the project.