Water tower cooling loop help

[MPdesign]

I have a water tower with an open loop condensing water system to plate heat exchanger then a closed loop in the building. Why? I know the possible reasons of ease of future addition & isloation for chemical treatment - but why else?

Also, there is a second heat exchanger (appears to be shell and tube). Why?

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[mgbinspect]

Terence's response that follows reveals that I completely misunderstood the question. So, since I can't altogether delete my reply, to spare readers time and to keep this thread on track, I've eliminated the content.

Pretty cool technology, though. (No pun intended...), which goes way beyond my limited understanding of chilled water cooling systems.

[Terence McCann]

What you have is a plate to plate heat exchanger and a shell and tube heat exchanger.

The plate to plate heat exchanger is used as an economizer (free cooling) in low outdoor ambient conditions. Tracing out the piping would show that two of the pipes (on the plate to plate heat exchanger) would have gone to the cooling tower, via either manual change over valves or motorized 3-way valves. The other two pipes would be the chilled water supply to the building (with the same type of valve configuration).

Bigger hi-rise buildings typically need cooling year around as the core of the building still needs to be cooled. With this system, in a low outdoor ambient condition, the cooling tower water goes through the plate to plate heat exchanger to provide necessary cooling to the building without running the electric chillers thereby saving $$.

The shell and tube heat exchanger is the condenser used for the chiller in the summer.

Free Cooling - a short paper on the subject.

[mgbinspect]

Terence,

My understanding of chilled water cooling systems is very basic 101, but this sounds fascinating.

I'm trying to grasp the concept here. Also, while I've already googled and understand what the two types of heat exchangers are, can you elaborate on the reason they are both employed?

I could not find good explanations for the difference in design and application of open and closed loop systems. Can one of you two take a moment to explain?

Thanks in advance.

[MPdesign]

Terance,

On the Shell and Tube Heat Exchanger, the building does not have a chiller. It has five 20 ton self contained units throughout the building.

Any idea of why the setup is like this with the two heat exchangers? It is an older building.

Thanks

[Terence McCann]

Terence,

My understanding of chilled water cooling systems is very basic 101, but this sounds fascinating.

I'm trying to grasp the concept here. Also, while I've already googled and understand what the two types of heat exchangers are, can you elaborate on the reason they are both employed?

I could not find good explanations for the difference in design and application of open and closed loop systems. Can one of you two take a moment to explain?

Thanks in advance.

Sure.

The shell and tube heat exchanger is meant for water cooled refrigeration systems - the refrigerant flows through the tubes and condenses from a gas to a liquid. The shell holds the water from the cooling tower that is the heat transfer source for the refrigerant. Eddy current tests are advised on the tubes of the condenser to check wall thickness. Refrigerant and water don't mix and will typically result in a compressor burnout on recip systems.

The plate to plate heat exchanger is a water liquid to water liquid heat exchanger. Manufacturing plants also use these to cool down cutting lubricants along with the cooling tower set up.

Google has a image finder that you can use to search for a cut-away of the construction of these items.

[Terence McCann]

Terance,

On the Shell and Tube Heat Exchanger, the building does not have a chiller. It has five 20 ton self contained units throughout the building.

Any idea of why the setup is like this with the two heat exchangers? It is an older building.

Thanks

Taken to direct email for the moment.