Air Cooled Screw Chiller Overview

Air cooled screw chillers are the king of the air cooled chiller market. 

At least for now. 

Screw compressors were doubted when they hit the market in the 90’s. 

As with everything, there were some learning curves. 

The efficiency and reliability they offer became a hit in the industry and manufacturers doubled down on the technology. 

Kinda like we see them do with some equipment today. 

The main struggle now is the noise but we cant have everything. 

Screw compressors can scale down really well in size but can also scale up tremendously.

There is a break over on both ends of this scaling where a scroll or centrifugal become the obvious better choice. 

While there have been screws put into the same circuit, the industry moved to adding circuits or scaling up the compressor. 

So for most systems, they will be single compressor circuits but up to 4 of them. 

Screws take two “screw bolts” a male and female to make compression. 

The male is typically your drive bolt connected to your motor. 

They also have a slide mechanism that adjust how much of the bolts can compress at a given time. 

This is where the magic of screws really caught on. 

Now we have a compressor that can match evap load thats not a centrifugal. 

There are limits to this staging. 

They took things a step further when they started making them variable speed compressors. 

These actually operate a little lower suction superheats of 4-12F. 

There is also a wider range of evaps used including DX shell & tube, Flooded, and falling film. 

The DX wil have an 8-10F and flooded/FF will be 3F of approach at high loads. 

MTT

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