Refrigerated Air Dryer

[boymekaniko]

Hi. So we are trying to make an air dryer design for our thesis project. I wanted to ask how to choose a liquid receiver for our design. and the amount of refrigerant needed. Our objective was to cool the air from 25 degree celsius to 3 degrees.
Thanks

[Rob White]

.

Don't start with the receiver.

Start by calculating the load on the evaporator first,
then you will be able to calculate the compressor, condenser
and the mass flow rates of the refrigerant.

That will tell you how much refrigerant you need and then you
can pick the size of the receiver.

To be honest though the receiver size is the least important component
on the whole system. the receiver needs to be large enough to hold
the entire refrigerant charge with a little bit of space left over for expansion.

Normal requirements are for an oversize of 10%.

Regards

Rob

.

[NoNickName]

Liquid receivers are quickly disappearing from modern refrigeration circuits, especially for those applications that have fixed and stable working conditions.
So, my answer here would be: "no liquid receiver needed".

[chemi-cool]

Don't forget the amount of air you want to cool.

[boymekaniko]

Thanks..now I know..really helps.. So our evaporator design is to wrap an air tank with copper coils..my problem is how to determine the surface are for heat transfer since most of the books focus on a direct coil contact..thanks again.

[chemi-cool]

It will not work,
You need heat exchanger of some kind.
You can not re invent the wheel. get an old scrap refrigerated air drier, take it apart and learn how doe's it work.

[nevinjohn]

Liquid receivers are quickly disappearing from modern refrigeration circuits, especially for those applications that have fixed and stable working conditions.
So, my answer here would be: "no liquid receiver needed".

So, under normal circumstances a domestic split unit has refrigerent in the entire pipe system I suppose? What is the state of refrigerent, liquid or gas (when the unit is turned off). I assume the entire system should be vapour as it absorves heat from the room, and from outside (for the condensing unit)?

Will there be a liqid flow back to the compressor once the unit (compressor) turns off when the desired temperature is reached? Is there any preventive circuit for this? - I am reffering to the discharge line.