Question about Sub Cool and Reciever

[conca]

Hi, thanks for viewing my question from a newb.

I have a refrigeration unit consist of Compressor>Condenser>Reciever>Subcool>TX valve>DX coil.

1) what is the purpose of having a reciever in this unit?

2) Why do we need to cool the liquid again with the Sub Cool Coil? What is the purpose of the Sub Cool Coil?

3) By having the reciever and subcool work together, how do they make the unit more efficient?

Thank you for your answer

[Quixote]

Conca,

I'll take a stab at this.

1.) The purpose of the reciever is to insure a steady column of liquid, without influencing the condensor capacity, under varying load conditions.

2.) The liquid can not be cooled below saturation when there is uncondensed vapor. If you look at nearly all condensors the liquid is collected and then ran back through a couple of passes. This is the subcooler section of your condensor, the bottom passes. The subcooled refrigerant offers greater efficiency but the proof is in the enthalpy chart. You will have to take that point on faith. Also, some subcooling is required to compensate for small pressure drops in the liquid line, preventing flash gas.

3.) Refering to answer 1, I see that the subcooler will get a steady stream of liquid. For the same the same size subcooler you might get an extra bit of capacity because the reciever will subcool slightly, preventing flash at entrance of the subcooler.

Just $.02 from an old tired tech, Hope you get an A,
Mike

[The Doctor]

Does this system have a headmaster valve?

[conca]

Quixote,
thanks for the post, it helps alot.


The Doctor,

Yes this system has a DIFFERENTIAL VALVE (Sporlan Ord 4) and a Head Pressure Control Vavle (Sporlan Ori 6).
If you can also explain the reason for why these two valves work in conjunction with each other.

thanks DOC

[Andy Schoen]

Anytime flooded heat pressure control valve(s) is (are) used, e.g., ORI and ORD, a receiver must be present in the system. This allows an area for the excess refrigerant in the system to be stored when it is not needed to flood the condenser for head pressure control.

The ORI valve backs up liquid refrigerant into the condenser during low ambient temperatures to maintain head pressure. The ORD valve bypasses hot gas to the receiver to maintain receiver pressure during this time since the ORI must restrict refrigerant flow to back up liquid refrigerant. See following: http://sporlan.jandrewschoen.com/90-30.pdf