Changing from Glycol to Water Cooled Chiller

[Chiboy01]

Hi everyone,
Please can I get a typical design changing from Glycol HVAC system to water cooled chiller HVAC system. I am tasked with changing an existing glycol chiller system to a water cooled system. Thank you and open for you professional advice.
Thank you everyone.

 

[HVAC-Novice]

So the reason for the need of glycol disappeared? what else changed?

This should be possible and performance of the existing system should improve. You have to make sure water in the chiller doesn't get too cold.

you have to hire an engineer to analyze the existing system and determine what modifications are required. Also should talk to the manufacturer.

 

[georgeverghese]

Reasons for a glycol water coolant selection :

a) This coolant may in turn be chilled at an ammonia or propane refrigeration unit's evaporator, where the heat exchanger tube surface skin temp ( on the coolant side of the tubes )may be < 0degC. So check that tube skin temp here (at the cold end of this evaporator, where tubeskin temp would be coldest at low flow coolant rate) is well above 0degC. You may need to calculate this yourself, as it is quite likely this info is not in the thermal datasheet for this ammonia - glycol/water chiller HX. Else get the amm - glycol water chiller thermal designers to run these calcs for you. Failure to do this calc correctly could result in thermal duty failure at this chiller, which in turn leads to lower cooling capacity for your HVAC system.

b) Lower corrosion rates with inhibited glycol water

Disadvantage with glycol water mix as coolant is poorer heat transfer capability compared to water, mainly due to higher viscosity of EG-water mix.

 

[HVAC-Novice]

Reasons for a glycol water coolant selection :

b) Lower corrosion rates with inhibited glycol water

IMHO, freeze protection is the only valid reason for glycol. The pH buffers, oxygen scavengers, and corrosion inhibitors can be added to regular water as well.

The most important thing you can do to protect from corrosion is to provide good de-aeration and not use open interfaces (e.g. air-coupled expansion tanks)

 

[LittleInch]

What though is your planned chilled water temperature?

Be aware that the chiller HX actual metal temperature at the point of contact with a thin film of water may easily be <0C, especially on shit down or even start up when there isn't sufficient warmer fluid to melt the ice which will form on the surface of the HX.

So unless you can guarantee that you have water flowing before you start the chiller and for a certain time after you stop the chiller then you could easily freeze your HX. Also if your CW temperature is too low, then the metal temperature even for flowing water will create a thin layer of ice which will grow over time.

And is this all inside?

There was a good reason why the current design was Glycol. what has changed to make you or someone else think you don't need it?