Design qestion

[nike123]

I recently started to work as backup in some fishing boat refrigeration, and peoples who makes cooling systems on fishing boats telling me a "story" that is much more efficient to cool glycol solution in refrigerant to glycol exchanger and than cool sea with that glycol in glycol to sea exchanger, than go direct with refrigerant to sea heat exchanger.
What is theory behind that? And are they talking fairytale?

[Tesla]

nike123
your right they are telling fairytails. It is more efficient to transfer heat directly to sea water. They are trying to baffle you with bullsheep

[Segei]

I recently started to work as backup in some fishing boat refrigeration, and peoples who makes cooling systems on fishing boats telling me a "story" that is much more efficient to cool glycol solution in refrigerant to glycol exchanger and than cool sea with that glycol in glycol to sea exchanger, than go direct with refrigerant to sea heat exchanger.
What is theory behind that? And are they talking fairytale?

This is matter of safety not efficiency. Direct heat transfer is always better than indirect.

[Magoo]

Well NIKE 123, I was going to say ....... But it is cool that you opened topic for general discussion.
magoo

[desA]

They seem to be using a secondary loop for protection. Let the seawater-glycol act as sacrificial unit, to save the refrig-glycol system.

The secondary loop system will be less efficient since you need to establish a driving temperature gradient between refrigerant-glycol-seawater.

[Magoo]

Nike 123 .
What ever you do be carefull on an written statements on performance. here , if anything goes wrong and the ships catch is de-rated for any refrigeration issues, the skipper/ compaqny will sue for lost catch potential.
So be very carefull on any advise and design.

magoo

[michaelm]

I recently started to work as backup in some fishing boat refrigeration, and peoples who makes cooling systems on fishing boats telling me a "story" that is much more efficient to cool glycol solution in refrigerant to glycol exchanger and than cool sea with that glycol in glycol to sea exchanger, than go direct with refrigerant to sea heat exchanger.
What is theory behind that? And are they talking fairytale?

B”H

They suggest that two temperature differences is better than a single one. The second heat exchanger will be even less efficient because of the smaller dT. Beside the point that you cannot compare thermal properties of seawater and glycol.