DX Evaporator

[jamesk]

Can someone please enlighten me, does this mean Direct Expansion or Dry Expansion? I have looked it up and have found both meanings on here and google.

I am trying to understand the Coolpak software, which I hope will help me understand the thermodynamics of the various stages of the refrigeration process (vapour compression cycle), which will eventually allow me to understand my project a bit better :D ? :( ?

Would love some help on DX Expansion's real meaning, thank you
James

[1mikeefc1]

I've always known Dx as direct expansion myself.

[Grizzly]

Direct expansion
I would assume the Term dry refers to the prefered refrigerant vapour state?
Grizzly

[PaulZ]

Hi James
I am the same as mike and Grizzly, I have always known it as Direct Expansion, I would say both terms are correct. In Principles of Refrigeration by Dossat it refers to Dry Expansion where the liquid refrigerant has completely vaporized by the time it reaches the end of the evaporator. In the real world it is referred to as Direct expansion.
Paul

[Grizzly]

Hi Again.
Paul's quote, Helps a lot.
Dry- opposite to Wet!

On a flooded system the system return is refered to as a Wet return.
Which is obviously a mix of vapour and Liquid.
This return is not directly connected to the comp suction.
So Liquid carry over is not a problem as the return is liquid with flash gas.
So if the line is refered to as a Wet return, why not call a suction line a dry return?

Although technically it may well not be so!
Grizzly

[jamesk]

Thanks guys for replies,
I will assume it means Direct Expansion in this case then as the software seems to be aimed more towards technicians and uses DX everywhere without explanation, so it must expect people to take its meaning as the more popular one.

Cheers, James

[jamesk]

Also, what exactly is the meaning of Direct Expansion?

I have got the meaning of Direct Expansion to mean: 'Evaporator is in Direct contact with the air stream, so the cooling coil of the airside loop is also the evaporator of the refrigeration loop. The term 'Direct' refers to the position of the evap. with respect to the airside loop.'

I'm a bit confused because airside loop seems to refer only to something in air-conditioning and I can't find it to do with refrigerators.

Any knowledge is appreciated cheers

[Rob White]

Also, what exactly is the meaning of Direct Expansion?

I have got the meaning of Direct Expansion to mean: 'Evaporator is in Direct contact with the air stream, so the cooling coil of the airside loop is also the evaporator of the refrigeration loop. The term 'Direct' refers to the position of the evap. with respect to the airside loop.'

I'm a bit confused because airside loop seems to refer only to something in air-conditioning and I can't find it to do with refrigerators.

Any knowledge is appreciated cheers


Direct expansion means the refrigerant is directly expanded into the evap.

The expansion device is connected as close to the evap as possible and the
refrigerant is directly expanded into the evaporator from that point.

As others have said in a DX system the liquid refrigerant should evaporate before
leaving the evap coil and therefore the refrigerant is (or should be) dry when it exits
the evap coil (hence dry expansion or direct expansion)..
Regards

Rob

.

[Rob White]

Also, what exactly is the meaning of Direct Expansion?

I have got the meaning of Direct Expansion to mean: 'Evaporator is in Direct contact with the air stream, so the cooling coil of the airside loop is also the evaporator of the refrigeration loop. The term 'Direct' refers to the position of the evap. with respect to the airside loop.'

I'm a bit confused because airside loop seems to refer only to something in air-conditioning and I can't find it to do with refrigerators.

Any knowledge is appreciated cheers


The conditioned air is air off the evaporator, the air that carries the sensible
and latent heat from the space being cooled and back to the evap is called return air.

This is the airside loop and is very American.
We tend to just refer to suply and return air or conditioned air.

Regards

Rob

.

[jamesk]

Thank you very much Rob. I have taken all of that in, slowly understanding refrigeration, it is such a LARGE subject its hard to get my head around.
James

[moideen]

Can someone please enlighten me, does this mean Direct Expansion or Dry Expansion? I have looked it up and have found both meanings on here and google.

I am trying to understand the Coolpak software, which I hope will help me understand the thermodynamics of the various stages of the refrigeration process (vapour compression cycle), which will eventually allow me to understand my project a bit better :D ? :( ?

Would love some help on DX Expansion's real meaning, thank you
James

go to this link,

http://www.mediafire.com/?mka9bga66ncutr5.

[r.bartlett]

Thank you very much Rob. I have taken all of that in, slowly understanding refrigeration, it is such a LARGE subject its hard to get my head around.
James

When I first went back to college to retrain into ac I thought "Whats in an fridge -it stands in the corner and gets cold"

I know know it's when it doesn't get cold the fun begins...