Fridge pipes

[sailaboutvic]

Just curious , there two pipe running from the danfoss compressor on my danfoss , one goes into the other I take it the small one is the HP pipe and the biggest one is the low pressure pipe .
As they both enter the plate what happens? Do they open up into the same chamber ?
or do they go into its own chamber ?

 

[pvb]

The small, high pressure pipe enters the evaporator plate, where the pressurised liquid refrigerant expands into gas - this process absorbs heat, thus providing the cooling effect. The gas then flows back to the compressor through the bigger pipe, and gets compressed into liquid form, etc, etc.

 

[sailaboutvic]

The small, high pressure pipe enters the evaporator plate, where the pressurised liquid refrigerant expands into gas - this process absorbs heat, thus providing the cooling effect. The gas then flows back to the compressor through the bigger pipe, and gets compressed into liquid form, etc, etc.

Thanks for that , I do know that ,what I was asking was is ther any thing on the end of the HP pipe to stop liquid being pushed back into the pipe , or is it just an open end and it's the pressure that keep the liquid moving around the plate turning it into gas , has anyone every had one of these plates open?

 

[pvb]

Thanks for that , I do know that ,what I was asking was is ther any thing on the end of the HP pipe to stop liquid being pushed back into the pipe , or is it just an open end and it's the pressure that keep the liquid moving around the plate turning it into gas , has anyone every had one of these plates open?

It's just an open end.

 

[sailaboutvic]

It's just an open end.

Ok thanks you answered my question

 

[superheat6k]

Can you post some photos of the pipes where they combine, as there must also be a condenser. The hot discharge could be de-superheated by the cold suction pipe, but they must separate again for the hot gas to be routed to the condenser.

I wonder if what you describe is a water pipe jacket condenser, so the hot HP gas in the smaller pipe is being cooled by seawater in the larger pipe, in which case there will be an outlet for the water and also a very narrow capillary tube providing the necessary pressure drop to the evaporator.

There must be some form of condenser.

 

[sailaboutvic]

Can you post some photos of the pipes where they combine, as there must also be a condenser. The hot discharge could be de-superheated by the cold suction pipe, but they must separate again for the hot gas to be routed to the condenser.

I wonder if what you describe is a water pipe jacket condenser, so the hot HP gas in the smaller pipe is being cooled by seawater in the larger pipe, in which case there will be an outlet for the water and also a very narrow capillary tube providing the necessary pressure drop to the evaporator.

There must be some form of condenser.

Can't get in there to take a photo .
But if it's any help it's a keel cooler unit , has I sure you know from the Evaporatore plate there a micro pipe inside a bigger pipe probably 8mm in the end there two connections one goes to the keel cooler the other to the compressor.
I know how the fridge works no need to explain it, what I am interested in is , the small micro pipe where it enter the Evaporatore plate , what stop any gasses returning down that pipe ? Is it just the HP from that pipe or is there some kind of valve just as it enter there plate ? I notice some other Evaporatore plates in a shop and there pipes enter the Evaporatore plate in different places and not inside one another , so for what reason on a boat they in this way ? Is it just to save room ?
There a few question in this posting ?

 

[Heckler]

Can't get in there to take a photo .
But if it's any help it's a keel cooler unit , has I sure you know from the Evaporatore plate there a micro pipe inside a bigger pipe probably 8mm in the end there two connections one goes to the keel cooler the other to the compressor.
I know how the fridge works no need to explain it, what I am interested in is , the small micro pipe where it enter the Evaporatore plate , what stop any gasses returning down that pipe ? Is it just the HP from that pipe or is there some kind of valve just as it enter there plate ? I notice some other Evaporatore plates in a shop and there pipes enter the Evaporatore plate in different places and not inside one another , so for what reason on a boat they in this way ? Is it just to save room ?
There a few question in this posting ?

The smaller pipe acts as the “expansion valve” ie it restricts the flow of the warm condensate. When the restriction ends that is where the liquid starts to expand to cause the cooling effect. The liquid continues to expand across the whole of the evaporator. on our simple systems that thin pipe comes from the condenser or water coil. The thicker pipe from the evaporator goes back to the suction side of the compressor. you can tell if you have too much gas in the system, simplistically speaking, if the frost line starts to move along that towards the compressor, basically all the liquid hasnt expanded and is continuing to expand as it goes back towards the compressor. In extreme cases it can enter the suction side of the compressor and destroy it.
Think of the system as a pipe that is being sucked on and the expansion valve pipe is acting as a restrictor.

 

[Daverw]

Pressure difference, small pipe pressure about approx 10bar (hip liquid) into the evaporator plate and larger pipe (suction) approx 2bar, that’s around 8 bar differential, systems closed loop so can only go one way round.

Common on evaporator plates to have both going into one end, if you look at the plate it’s atually takes to the end on the plate internally. Many domestic fridges are also like this. Makes manufacturing and installation simple.

Anything bigger will have a pipe matrix with flow and return pipe headers.