Flooded evaporator with pumped

[sorin_ache]

Hi everybody,

It’s the first time in this forum.
I’m engineer from Romania and I have a new project.

I want to build one installation with pump circulation.
The refrigerant agent is R404A.

For this I need some brands (in Europe) for liquid separators and for pumps.

Regards!

[dogma]

More info?

[US Iceman]

Welcome to RE.

Why do you want to use R-404a?

And, how are you planning to recover the oil in the separator?

I do like the fact that someone is considering a liquid overfeed system though. instead of direct expansion.

[cretan]

Welcome to RE.

Why do you want to use R-404a?

And, how are you planning to recover the oil in the separator?

I do like the fact that someone is considering a liquid overfeed system though. instead of direct expansion.

Just curious,what is a liquid overfeed system?

[US Iceman]

Just curious,what is a liquid overfeed system?

A fair question...

A liquid overfeed system may also be called a liquid recirculation system. Both of these names mand the same thing.

In a direct expansion system using thermostatic expansion valves (TXV's), the discharge pressure provides the force to push liquid refrigerant to the TXV. Since the liquid refrigerant is at discharge pressure, we call this high pressure liquid feed. Direct expansion means the liquid refrigerant expands into a gas and liquid mixture in the evaporator. The gas helps to distribute the remaining liquid into each of the evaporator circuits by use of a distributor. The evaporator has superheat in this example.

In a liquid overfeed system, a refrigerant pump circulates low pressure liquid refrigerant to the evaporator. The pump pulls this low pressure liquid refrigerant frmo a vessel usually located directly above the pumps. The liquid is metered into the evaporator using what we call a hand expansion valve (not thermostatically controlled). In this case, the evaporator should have zero superheat as some liquid flows out of the evaporator. This normal for this type of system.

On a DX evaporator there should be no liquid leaving the coil. Hence, the higher superheat.

[cretan]

A fair question...

A liquid overfeed system may also be called a liquid recirculation system. Both of these names mand the same thing.

In a direct expansion system using thermostatic expansion valves (TXV's), the discharge pressure provides the force to push liquid refrigerant to the TXV. Since the liquid refrigerant is at discharge pressure, we call this high pressure liquid feed. Direct expansion means the liquid refrigerant expands into a gas and liquid mixture in the evaporator. The gas helps to distribute the remaining liquid into each of the evaporator circuits by use of a distributor. The evaporator has superheat in this example.

In a liquid overfeed system, a refrigerant pump circulates low pressure liquid refrigerant to the evaporator. The pump pulls this low pressure liquid refrigerant frmo a vessel usually located directly above the pumps. The liquid is metered into the evaporator using what we call a hand expansion valve (not thermostatically controlled). In this case, the evaporator should have zero superheat as some liquid flows out of the evaporator. This normal for this type of system.

On a DX evaporator there should be no liquid leaving the coil. Hence, the higher superheat.

Thanks Ice.I would have to see one to get a clearer picture.

[Brian_UK]

There is some text and diagrams here which might help you....

http://books.google.co.uk/books?id=3...um=5&ct=result

[cretan]

Thanks for the link.

[wilsoncheung]

The link is quite a nice book,thanks!

[Slatts]

I remember in the late seventies, when I was an apprentice, working on an R12 domestic fridge that was ancient even then. It had a lowside float that flooded the evap in much the same way as your liquid overfeed system.
I don't recall the return from the evap coming back to the float chamber though. it would have relied on a critical charge and suction accumulator to stop it from flooding back.