Enviormental Chamber Question

[MaxPoon]

I have to rebuild an environmental chamber, and that environmental chamber need to be holding constant temperature(within 3 degree C) in a range of 20 to 25 and 30 to 35.

So I have an idea of routing a air compressor, condenser, evaporator, and a valve which could alternate the flow of refrigerant. so when I need the enviormental chamber hotter the valve can make this "air conditioning system" hotter, and colder the other way.

My question is:
Is this going to work like this, if not, any suggestion will be appreciate.

What kind of refrigerant should I use?

Also, is there anything that I need to be aware of.

I am totally new to refrigerant system

[GXMPLX]

Don't understat what you want to do with an air compressor!

Take hot and cold air from the refrigeration system?

Where will you get thermal load for the system from?

In a normal syste any attempt to controll such a short differential will cause cycling problems unless you use an air handler with two coils.

One coil for refrigeration as usual, another for heating.

The design/controll of this system is not easy and beyond what I can do for you in these posts.

[chemi-cool]

Are you a magician??

[MaxPoon]

So is there anyway to make this to work, that's the job that my boss give me, and I have no clue about refrigeration.

[GXMPLX]

So is there anyway to make this to work, that's the job that my boss give me, and I have no clue about refrigeration.


You could:
Use a refrigeration system the usual way with a refrigeration compressor and the evaporator in the room.
Use the air compressor to draw in hot air from the condenser air discharge when you need to heat the room but the only way to distribute the air correctly is discharging the air evenly into the air suction of the evaporator. This would make your refrigeration system work like a wild horse!

Any attempt to use the air compressor for refrigeration will fail.

Don't tell anybody here I suggested this!

[US Iceman]

So is there anyway to make this to work?


Call someone who has worked on applications where environmental chambers are used!

These are very precisely controlled and tend to be complex systems due to the close tolerances required for temperature.

If you have no refrigeration experience, you should be willing to call and pay someone for the expertise.

These chambers are NOT just a walk-in cooler....

[majo]

just call the guys from thermotron USA :)

[Zpoint]

Piece of cake.

Install an insulated hot gas line running from the discharge of the compressor to the point between the TXV and the distributor on the evaporator coil.

Install a hot gas solenoid valve near the compressor.

Use a digital temperature controller, set the Diff. to
1 deg c

When cooling cut-out is reached, instead of shutting off the compressor, energize the hot gas solenoid.
When cooling cut in is reached, de-energize the hot gas sol'n.

This means that your compressor will always be running. This method will actually extend the life of the compressor due to minimal starts/stops.

This also provides the heating mode you need to reach your higher temperature setpoints.

Just make sure you install a suction accumulator, and size your lines properly paying attention to proper oil return.

You don't need any extra or special evap. coils, size them like a normal system.

Make sure to insulate your hot gas line from compressor to evap.

You can get accurate control with this configuration, as close as plus or minus 0.5 deg F

You don't need a shut off sol'n on the liquid line for temp. control, only for pump down cycle when shutting down system.

I hope this helps, if you have questions ,...feel free.

Jeff P.

[Gary]

I have to rebuild an environmental chamber, and that environmental chamber need to be holding constant temperature(within 3 degree C) in a range of 20 to 25 and 30 to 35.

So I have an idea of routing a air compressor, condenser, evaporator, and a valve which could alternate the flow of refrigerant. so when I need the enviormental chamber hotter the valve can make this "air conditioning system" hotter, and colder the other way.

My question is:
Is this going to work like this, if not, any suggestion will be appreciate.

What kind of refrigerant should I use?

Also, is there anything that I need to be aware of.

I am totally new to refrigerant system

As I understand it, you are not building the system, you are rebuilding the system.

How is it currently being done?

[Brian_UK]

I wouldn't worry Gary, the OP was two years ago and the thread is only revived by Zpoint as he has an interest in these things. :)

[Gary]

Somehow, I always miss the OP date... gets me every time... lol

[Zpoint]

So sorry,

I will check op date from now on.

Just trying to help.:cool: