Refrigerant distributors

[PaulLag]

Hi there
Hope everybody is fine !
Please, I'd need your help as follows
I have been asked to calculate the pressure drop in a refrigerant distributor.

From manufacturers' catalogues, I assume this value is around 14 PSI.
Nonetheless, I'd like to know if anybody could provide me a literature reference in order to find a more specific way to calculate this pressure drop

Please, can anybody help me ?

Thanks in advance !

 

[willard3]

Try measuring the inlet and outlet pressure when the system is operating.

 

[PaulLag]

Hi !

many thanks for your answer.
Indeed I tried to measure it, but I got really lots of problems.
I have been explained from who is more expert than me that this measurement is not so precise and stable, so that this is not unfortunately a good solution.

This is the reason why I am looking for some literature data.

Regards

 

[willard3]

How do you think the manufacturer measures pressure drop?

 

[HVACMech]

Your pressure should fluctuate quite a bit. Since your distributor is working for a temp it will be changing the pressure based on the temperatures. I don't think you will find a good number...

 

[PaulLag]

@willard3
I don't know how manufacturer measures pressure drop, or better, according to what they claim the specified pressure drop.
I was wondering indeed if they have a theoretical method

 

[EnergyProfessional]

If this is for a new system you are designing, the manufacturer of the equipment calculates that for you. they also design the oil traps etc. For simpel system, like a mini-split they jsut give some general guidance on line size, maximum lengths etc. but for VRF, or chillers etc. they do job-specific calcs.
it is very proprietary since they need to ensure the oil returns to the compressor.

If you just want to calculate pressure drop for a homework, use EES

If this is an existing system, measuring is the way to go. Yes it will fluctuate since with different operating conditions pressure and temps and flowrates and viscosity will change. And if you have multiple or variable speed compressors, even more.

 

[PaulLag]

@EnergyProfessional

Many thanks
You got the point in your answer
Indeed I can utilize EES, but my question is: which formulas shall I implement in calculation ?
Is there a literature model I can utilize ?

I am not able to find it in literature.

thanks

 

[dbill74]

Based on what I found doing a quick google search, you really have not provided enough information to get an answer.

I'd wager you haven't found a "literature model" because there isn't one. Every distributor model/design is going to have different equations for pressure drop through them.

Basically, you need to know the tube/pipe configuration and sizes within the distributor. You are going to have to build a model to calculate the pressure through each segment. Then calculate for each path.