Flooded & Pump Evaporators

[MrReds]

Hallo to everybody !
Please, I'd need a clarification from you.

I've seen a lot of threads concerning flooded evaporators.
What I'd like to know is: are a flooded evaporator and a pump evaporator the same thing ?
Is there any difference in their circuitation and in their circuitation with respect of DX evaporators ?

If there is, is there any technical reason for this difference ?

Many thanks !

[US Iceman]

There are two types of flooded evaporators.

1) A shell & tube flooded (on the shellside) evaporator uses pool boiling as the main mechanism.

2) a flooded plate heat exchanger or air-cooling coil uses forced convection boiling as the main mechanism.

For an air-cooling coil you can use either pumped recirculation (overfeed) or gravity flooded. The only major difference in construction of the coil is the coil circuiting.

DX evaporators have all vapor exiting the coil. On either flooded or overfeed liquid feed you have liquid and vapor exiting the heat exchanger.

The reason for using flooded or overfeed is due to higher performance (more heat transfer). The excess liquid exiting the heat exchanger provides a fully wetted suface, where the DX uses part of the surface for superheating the vapor.

[NH3LVR]

Hello MrReds
The answer to your question about flooded and pumped evaps is-sort of.
A pumped Evap is flooded, but a flooded is not always pumped.
Seriously, a flooded evap can be flooded by a surge drum mounted over the evap, or by a liquid pump.
A pumped evap uses a liquid pump to supply liquid to the evap. You supply more than can be evaporated, the liquid not evaporated being returned to a Low Pressure Receiver sometimes called a Recirculator. .
A DX system always has to have gas only at the exit. The Themal Expansion valve controls superheat, so that no liquid goes back to the compressor.
The advantage of flooded is that more of the interior coil surface is wet. This allows for greater efficiency's in the system.
If you need examples we can probably provide some.

[MrReds]

Many thanks to everybody !
Please Mr. NH3LVR, I would be grateful if you could provide me some example !

Thanks in advance !