
 Ships, Bananas, Logistics, Math and a Big Dose of Engineering - rahuldottech
https://twitter.com/cybergibbons/status/1213572501395120134
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weinzierl
> Those reefer positions all need power. We used to factor around 4kW for a
> reefer... so that would be around 4MW total. Easy! Problem is, bananas are
> not average. Most frozen cargo is taken onboard frozen. It doesn't take much
> power to keep it frozen at -21degC

> Bananas are different though - they are often packed warm, and brought
> directly to the ship. They are also kept at +14degC. This means the
> refrigeration needs to work harder.

> We are now looking at as much as 20kW to cool that container when it comes
> onboard, and 8kW to maintain the temperature. We've jumped to 8MW at least!

I don't buy that. Sure, cooling to 14C will require some extra energy for a
limited amount of time, but why would 4 kW be enough to keep a -21C container
at that temperature while it takes 8 kW to keep a container at 14 C. Doesn't
make any sense. Of course that doesn't mean the conclusion that regular
container ships cannot go 100% bananas is wrong. At least @cybergibbons seems
know what they are talking about. I just think there is a gap in the
argumentation or that I just misunderstood.

EDIT: @cybergibbons address this objection [1]. What I understand is that
frozen cargo is stored at -21C but then _allowed to warm up_ wheres bananas
are cooled and then held at a constant temperature in the ship.

[1]
[https://twitter.com/cybergibbons/status/1213593041740664832](https://twitter.com/cybergibbons/status/1213593041740664832)

~~~
jamez1
It takes a lot of energy for matter to change states from frozen. This would
be a large buffer:

[https://en.wikipedia.org/wiki/Latent_heat](https://en.wikipedia.org/wiki/Latent_heat)

