Receiver! Needed or not

[The MG Pony]

A/C's Heat pumps and other such "comfort" cooling you will have noticed no receiver, yet, they will use TXVs! How do they pull this off? They over size the condenser and flood 3-5 rows and use that as part of their receiver but the system becomes a critical charge system! Another reason why they can get away with it is relatively stable load once under operation.


Now, technically, any system can be don this way, a Receiver just makes charging far easier and is more forgiving to error in charging. How ever it demands a higher system charge, and is an added risk of leakage or failure point, and drives cost of production up!

A critical charge system on the other hand, reduces net system charge, less potential failure points. How ever, not forgiving to charging errors, and must be care fully charged which can be time consuming and can at times perform poorly on low ambient environments, which a receiver would other wise benefit on good sub-cooling!

So, In the end, with care full thought for design, and in a situation where evap load remains relatively stable a receiver is not required, but rather, is an option

Thats what I wrote in another forum, and to my current understanding is correct. Is this correct? What have I missed if any thing (Hard to believe I didn't if thats the case! lol)

All so what are your opinions on receiverless systems?

[Peter_1]

I think, you're 100% right.
We have a Carrier running of 600 kW cooling capacity without receiver.

You can go even further in your way of thinking: if the load on the evaporator decreases, then you will inject less refrigerant.
If you inject less refrigerant in the evaporator, the remaining refrigerant can then be stored in the condensor because with this smaller load, you need less condensor area. So, you then have spare volume in the condensor to store this 'excess' refrigerant.
But... as you said, the system needs to be charged very critically and must work with a more or less stable condensing pressure.

If you store some liquid in the lower part, you then have a perfect subcooler.

[The MG Pony]

Thanks peter for the reassurance, right now the forum that was posted to is doing maintanance, but once up I'll put a link to it.

http://www.xtremesystems.org/forums/showthread.php?p=2385858&posted=1#post2385858

[paul_h]

You're a member of extreme systems? I know a guy there called kayl.
As far as your reciever question, it's mainly there for a variable load, ie, you charge the system a full load to get liquid to the TXV, when the load drops, the reciever holds the excess. If the load is constant you don't need a reciever, but of course loads and condenser air on and subcooling always change, that's where the charge becomes critical.
So for a generic ambient and load a receiver is best, for a specified constant load and ambient you can go without a receiver, and if you oversize the condenser, that covers both situations.

[The MG Pony]

Ya, it was more a statement then a question, thats exactly what I was saying, How ever one guy is holding firm on the receiver is a must camp.

I'm trying to logicaly help him see that although it makes life easier it is more an option.