Fishing trawler bait freezer

[beachbum]

Hello there everybody. I been on this site for awhile and learned alot from you guys so thank you. Now I have a question regarding a freezer room on a fishing trawler. The evaporator coil is run in steel pipe layed out over walls and ceiling not forced draught. The previous company has replaced 4 or 5 Bitzer 6 cylinder compressors over 2 years which I believe has to do with the system running on R22 and low temp, no liquid injection to help with high discharge temps. I also have a thought that the compressor is too big for the job. So my question is, what are the calculations I need to do to calculate refrigeration capacity of coil so I can confirm compressor installed has been sized correctly or incorrectly. Can't seem to find any info on the net. Any advice you boys could share with me would be much appreciated.
Cheers
Greg

[The Viking]

Is the system currently operational?

[Tycho]

If I understand you correctly, you have pipes running along the walls and ceilings of your cargo hold, so it's a simple direct expansion system with a thermo expansion valve for the one line, or one thermo expansion valve for each of the lines roof/walls.
You gave a compressor with a receiver tank? defrost is by just stopping the compressor?

From what you say, if you are still on R-22, it's either a faulty expansion valve, expansion valve set to to low super heat, causing liquid to enter the compressors and thus break it down, either by liquid slugging, or because of to much refrigerant in the oil causing it to break down.