Refrigeration Design

Good day all,

I am currently studying a Marine Engineering Degree and in my energy management and efficiency module I have been tasked with the following:

Produce a design report detailing the specification for a refirgeration sysetm to be fitted to a refrigerated ISO Container (40ft), The container has a high value cargo that needs to be maintained at a temperature of -60C in ambient conditions that can be up to 40C

I am struggling to figure out where to begin in the design stage of the plant and was wondering if any tips or advice can be given by yourselves. Any input is appreciated.

Many thanks

1) Select a refrigerant. That spread of temperatures is going to limit it considerably....
2) Research suitable compressors. Same conditions are going to make that a pretty narrow search for a single fluid system. Also you will need to know power source and some idea of thermal requirement. Start at 30KW of cooling...
3) Confirm a suitable lubricant. to suit range of refrigerants and compressors...
4) If you are now stuck, you need to consider a more complex cycle....Transcritical CO2 will not quite get there; autocascade will but is kind of fancy for normal servicing; compound compression might be suitable with the right fluid but conventional cascade would be high on my list.

if the objective here is to save power: the cycle wants to be decent but at least as important is door seals and vapor seals and insulation, etc. at those temps...as is traffic considerations: the actual operation that is; is this thing going to get accessed once a week or 5-times a day or?