Thermostatic expansion valves

[tadipatrir]

Can anyone please explain me what happens to the system if 100% gas enters the thermostatic expansion valve in refrigeration application.

[lana]

NOTHING.:eek:

What I mean is there will be no cooling in the evaporator. TEV is to create pressure drop for the liquid to produce lower temperature. This low pressure and temperature liquid is going into the evaporator and by evaporation (latent heat) absorbs heat. When there is no liquid in the evaporator then .... you can picture the problem.
Cheers

[Samarjit Sen]

Sorry to have popped in. Since this a thread on Expansion Valve I though I might put my question in this.

We need TEVs for 134a at a Condensing Temperature of 70 Deg. C. The ambient in this area is about 65 Deg. C. This is a steel plant project. I have been trying to search for Danfoss make TEV. Unfortunately Danfoss TEVs are rated for a maximum of 60 deg. C Condensing.

Can some one tell me what would be the derating factor for a 70 deg. C Condensing Temperature and a Liquid temperature of say 60 Deg. C.

[lana]

For that condensing temperature go for R124.
I presume it is an overhead crane AC.

Cheers

[Samarjit Sen]

Yes you are right Lana. It is an overhead crane. I had suggested R 124 as in another plant where the ambient goes upto 80 Deg. C, they have standardised R 124 for all their cranes.

Here in this particular plant they have specified for R 134a. Maybe I shall speak to Honeywel as they have a very wide variety of TEVs for various refrigerants. Further they are the only people who has the TEV for R 124.

[US Iceman]

Sporlan can provide a R-124 valve for this application. I worked on a project recently for a similar application.

[BESC5240]

... Unfortunately Danfoss TEVs are rated for a maximum of 60 deg. C Condensing.
....

Hi Samarjit Sen,

I do not know who gave you this idea, but this is not true.
Here are some maximum working pressures for Danfoss expasion valves:
type TU and TC (for R407C, R134a, ...) : 34 bar
type TU and TC (for R410A) : 42,5 bar
type TERE (for R407C, R134a, R410A, ...) : 42 bar
...
So condensing at +65°C is no problem.

Also Danfoss has TEV for R124. They're not in the standard catalogue, but the codes exsist and are on stock (in Europe, ...)

Best regards
BESC5240

[Samarjit Sen]

The refrigerant that is to be used is R 134a and the Condensing Temperature is 70 deg. C. The ambient temperature will be 60 Deg. C with short rise to 65 Deg. C. Considering all these, we have considered the Condensing Temperature to be 70 Deg. C.

For higher Condensing temperature, we have used R 124 as the refrigerant. About4 years ago Sporlon or Danfoss did not have Expansion Valves suitable for 124. At that time we had used Honeywell who had taken over the unit of Egelhof, Germany.

[BESC5240]

About4 years ago Sporlon or Danfoss did not have Expansion Valves suitable for 124. At that time we had used Honeywell who had taken over the unit of Egelhof, Germany.

Hi,
Danfoss has had R124 valves for more then 7 years now.

[Samarjit Sen]

In our country they have introduced it a few years ago. Danfoss has a vast range of TEVs, unfortunately all the models are not available here. Recently I was looking for a couple of B Range TEX 2. Unfortunately they do not have the same in India.

The Danfoss dealers for that reason any other product dealer only maintains a stock of the fast moving items.

[asad_mehrabadii]

NOTHING.:eek:

What I mean is there will be no cooling in the evaporator. TEV is to create pressure drop for the liquid to produce lower temperature. This low pressure and temperature liquid is going into the evaporator and by evaporation (latent heat) absorbs heat. When there is no liquid in the evaporator then .... you can picture the problem.
Cheers
excuse me sir:
I saw a system ,air drayer, thise system dosent has tev it has simple dstributor i think some time tev isn,t good for system that thay work arond +2 degre centegrad

[asad_mehrabadii]

dear sir:
I have question ,that it bothering me why some system like air drayer dosent has tev? it has simple distrubuter may some body asser?

[Brian_UK]

A simple system, such as an air dier, will have a steady load on it.

The control of cooling flow by capillary line and a critical charge should provide good control.

[Samarjit Sen]

Hi BESC5240,

You were last telling me about the Danfoss TEV. Could I have your expert advice for locating the model for R 134 at 5 Deg C Te, 70 Deg. C Tc suitable for 6.5 kw. I had adviced the party for R 124 as in some of the steel plants they have standardised R 124. But the avaibility is bad in our country. Now that Dupont has opened an office in India, they may help such projects with R 124 or R 236fa.

The problem still is with the TEVs. Honeywell has these most probably. I was trying to locate the multiplier factor for R 134a Tc 70 Deg. C but could not get it. Can you help.

With best regards,

[BESC5240]

Hi BESC5240,

You were last telling me about the Danfoss TEV. Could I have your expert advice for locating the model for R 134 at 5 Deg C Te, 70 Deg. C Tc suitable for 6.5 kw. I had adviced the party for R 124 as in some of the steel plants they have standardised R 124. But the avaibility is bad in our country. Now that Dupont has opened an office in India, they may help such projects with R 124 or R 236fa.

The problem still is with the TEVs. Honeywell has these most probably. I was trying to locate the multiplier factor for R 134a Tc 70 Deg. C but could not get it. Can you help.

With best regards,


Hi Samarjit Sen,

I would go for a TUAE R134a (code 068U2207 or 068U2215 with MOP+15°C) with orifice 07 (code 068U1037).
We don't have any official data for this application, however but we can calculate theoretically what a certain valve will do in conditions outside the 'standard' range. (In this case I have calculated with a subcooling of 2 K).
Best regards

[Arjuna]

can i know the detail about foolowing refrigeration valves.
automatic expanssion valve
thermostatic expanssion valve
capillary tube
low pressure slide float valve
high pressure slide float vavle
thermal electric valve

thanks.

[manojdiwan]

manoj here
there will be no cooling as no liquid enters exp valve

[suny]

Yes you are correct Mr. Samarjit. B range TEV are not available ex stock in our countries. I had make a special order to import B range TEV, through the Danfoss local agent.

Suny

[Paco villarreal]

Partners, I have the same need for VTE's for R-124 for climates of cranes, but here at Mexico there is nothing of this gas valves and in US anyone can get me something, someone of you to achieved a valve of these that might happen I contact provider, anywhere in the world. Greetings to all.

sorry for my bad english.