Pump for flooded evaporator

[zvig]

Help!!
How to calculate volume flow of the pump for
R-507 for flooded evaporator W=400kW, -40 C

[RANGER1]

Calculate amount of refrigerant flow through compressor and usually multiply by 4 for a 4 to 1 curculation ratio .

ie ciculate 4 kg refrigerant and only 1 kg turns to gas as a rough rule .

You may have to find out evaporator design circulation rate .

If its only 1 evaporator you may have a problem as pumps of this style could be way to big if small evaporator

[Dacosta]

The long answer…


Find the R-507 thermodynamic tables

Look up suction vapor enthalpy value
Look up the liquid feed enthalpy valve

Subtract the liquid enthalpy from the vapor enthalpy
This is your refrigeration effect

Divide your desired load (400kw) by the refrigeration effect
This is your mass flow rate

Divide your mass flow rate by your liquid density
This is your raw volumetric flow rate

Multiply your raw volumetric flow rate by the recirculation rate (say 4 for flooded)
This is the amount you need to pump.

[zvig]

How much Pump Circulation Rate
should be ?

[charlie n]

Circulation rate is a function of the circuit design within the evaporator. I've seen as low as 1.1 to 1 and as high as 5 to 1. 3 to 1 and 4 to 1 are most common for air cooling evaporators.

[zvig]

Circulation rate is a function of the circuit design within the evaporator. I've seen as low as 1.1 to 1 and as high as 5 to 1. 3 to 1 and 4 to 1 are most common for air cooling evaporators.

Thanks, but what is better for shock freezing -40C?

[charlie n]

Probably 4:1 is the most common recirculation rate. Ask your evaporator coil manufacturer. For example, one of the Canadian manufacturers makes down fed aluminum evaporators using 5:1 so it really depends on the evaporator design.

[Dacosta]

Remember R-507 is expensive, going 4-1 means you need to have a larger pipe to reduce the friction losses though the pipe. Also you will have a larger refrigerant charge. Your evaporator efficiency will go up with 4-1 but so will your costs. consider economizing on the liquid feed to say 2-1 or 3-1. This may save you money in the long run.

[charlie n]

Better still, build the freezer for ammonia.

[Magoo]

Hi Decosta.
very good explantion of what happens and what is required.
magoo

[zvig]

Better still, build the freezer for ammonia.

Unfortunately there is no permission

[charlie n]

I remember being told that about a skating rink installation in your country but I had hoped the authorities would have seen the light in the case of an industrial situation. Unfortunately not.