VRF system of Modular chiller 2

[Sheel0305]

thread403-340232
Hi,
I am trying to find the segments where Modular chillers can be used instead of VRF systems. I have read a lot of articles and research papers but was unable to find out significant difference between these two technologies. Some of the papers say VRF systems are better for smaller buildings and some say chillers give higher energy efficiency so they are better. It would be great if someone could help me in finding out the segments with reasons.

P.S. I am a marketing student (with no mechanical engineering background).

 

[Sheel0305]

The subject line is VRF system or Modular chiller. Sorry for the mistake.

 

[Drazen]

vrf's had more advanced modulation some time ago, but now water system are catching up to the much extent.

you cannot easily compare efficiencies until you know by design what temperature regime is needed or preferable.

the large advantage of water systems is that you can compose system of any components that fit capacity requirements. in vrf you are bound to one manufacturer and one model, which is hardly acceptable for larger buildings.

 

[dbill74]

The differences are significant. You’re not talking comparing apples to oranges; it’s more like apples to carrots.
VRF or variable refrigerant flow is a complete air conditioning system with numerous components from indoor fan coil units to condensing units outside the building.
Modular chillers are just one component in a much larger air conditioning system. These systems are called chilled water (CHW) systems. One thing that is important to note here is that a modular chiller will not be found in a VRF system.

At their most basic level, the differences between a VRF system and a CHW system is the fluid used to get heat energy out of a building (thereby providing cooling). A VRF system uses a refrigerant such as R-134a (similar to a typical residential heat pump) whereas a CHW system uses water (go figure).

As for which is more efficient, that is somewhat debatable. However, generally speaking VRF systems are better suited to small buildings; a couple thousand square feet in size with a handful of cooling zones. In theory they could challenge CHW system in large buildings, but due to safety concerns over their use of an oil based refrigerant, code requirements and pipe length limitations tend to limit VRF system sizes. A CHW system with modular chillers does not share the same safety concern or pipe length limitation as VRF systems having virtually no limit to the size of building a single system can serve.

If you want to truly understand the differences, I suggest finding a mechanical engineering professor at your school or contacting a local engineer that regularly designs Heating Ventilating and Air Conditioning (HVAC) systems.