using a TXV as a control valve for cooling water or air

[benson loh]

Hi,
I am thinking of using a TXV to control cooling using cold water or cold air for my pilot project as they are well built and readily available. The control temp or set point varies from 10 to 25 deg C and the coolant supply pressure is about 2 to 4 barg. I would appreciate if you could direct me to various models of TXV that can meet these requirements as most of the TXV seems to be for negative to less than 10 deg C set point. Thanks in advance.

Best Regards,
Benson

[Tesla]

Hi benson and welcome to our forum
This is old school - pressure control. Just remember that you will need a difference of temp control related to pressure, Pressure - Temperature relationship. Cut in pressure is dependent on/if defrost needs and if the fan runs during the off cycle. Fridgies used this control on many cool rooms etc when I was an apprentice then the electronic controls came in and other stuff. So you will need to use a pressure controller to start and stop the compressor which will control the amount of cooling the TXV does or an EEV and a pressure temperature sensor. You could put your age - we would be more divulging in information as we could relate more and not just talk to a page or some blankness.

[benson loh]

Dear Tesla,
need to add to my post that the cooling water or cooling air is that actual medium passing through the TXV.

[benson loh]

Sorry that I click the hide age too quickly. I am 50.

[Brian_UK]

There is a lot of useful information on TXV on the Sporlan website.

http://sporlanonline.com/literature-and-educational-materials/

[monkey spanners]

A txv will not work in any sensible way if its regulating air or water directly, you would be better off looking at a solenoid valve controlled by a thermostat and possible a tap or similar restrictor you can use to balance they cooling load with the available duty provided by the cooling medium.

[Tesla]

MS is right TEV = no good for this app
You could also use a two way water valve that uses a o to 10 volt dc signal. This is how it is done in many commercial buildings. You will also need a simple controller to generate the o to 10.
Thinking about it there is a ready made self regulating plumbing valve tap controller used in showers - it may be a little higher range of temp than you are after but some are adjustable.

[PaulZ]

Hi bensonThe valve Tesla is referring to is a tempering valve and I think they come in different ranges. There are many ways you can control the cooling depends how close to the set point you want to run. Any type of 3 way modulating valve would be suitable, these mix the warm return with the cold supply to achieve the desired temperature.Paul

[The MG Pony]

johnson controls V47 series valve, is a thermal statice water valve.

http://www.johnsoncontrols.com/content/us/en/products/building_efficiency/products-and-systems/commercial-refrigeration/commercial_refrigeration/valves/tempvalve/v43.html

[benson loh]

Hi everyone,
thank you very much for the information especially the Johnson control unit.
I need something mechanical and I was hoping the HVAC TXV could do the job since they are so readily available.

cheers Benson