The Worst pleasure boat refrigeration.

[GILow]

Originally Posted by robert sailor

Sure, sure you had to win the argument by buying a bloody new engine. Wasn't on my mind when I was thinking about fitting out a boat, lol. Having said that by the time you build a large arch for panels and add in a set of davits as part of it then add a genset or a high output alternator or both plus a large battery bank...the fridge is pretty cheap in comparison, oh don't forget a high quality controller for that big array of panels and if your not handy the labor costs to put it all together....this is not the cheap seats. I've done it several times over the years and other than installing a new engine it's one of the most expensive parts of outfitting a base boat.

Yeah, I cheated using the engine number, but the rest of it remains much as I said.

Just as I shouldn’t cheat by using the engine number, you can’t cheat and include all the solar costs against the fridge. After all, there are a few other systems on the boat that use power too, unless you navigate by sextant, light the boat with kero lamps and think a book you’ve read 38 times already is “home entertainment “.

The fridge adds a level of required output and storage to your electrical system needs, but in many cases, such as mine, I’d bet it doesn’t add all that much, since most of us pack in as much capacity as we can fit or afford. (Leaving aside those with a pathological dislike of solar panels and their attachment systems.)

[170122]

We like simplicity and reliability, but also efficiency is a must, Vitrifrigo and Isoterm cooling plates are easy to install and they deliver all of the above,

Originally Posted by Richard Kollmann

I would like to know from boaters about all the 12/24 volt boat icebox conversion refrigeration systems which one they least would want to install in their boat? When questions in the past were ask about best refrigeration every response is favorable even on less than desirable units.

If you respond list at least three reasons you would not want that refrigeration unit, Examples:
It requires water cooling to be efficient as air cooling alone is not enough.
It would require more maintenance than a much simpler system.
The evaporators available for this system are incorrectly sized for my boat’s box shape.
I believe this unit is reported to have more refrigerant leaks than other similar units.
Technicians and myself may not be able to keep it running where I will operate the boat.
I prefer a less expensive unit with the same performance.

[GILow]

Originally Posted by Mabruteam

We like simplicity and reliability, but also efficiency is a must, Vitrifrigo and Isoterm cooling plates are easy to install and they deliver all of the above,

Now that, as a house fridge would worry me. That’s a lot of exposed soft aluminium with delicate gas lines. Anyone puts something heavy or a little sharp in there and you’ve got a pretty high chance of a leak. Or even a long ocean passage on one tack causing something to rub through the plate.

This is why I think the eutectic tanks are not so bad for space. Once you’ve arranged adequate protection for those large aluminium evaporators you’ve lost as much or more space than you would from the eutectic tanks.

[170122]

I understand your dilemma, aluminum is week and could be perforated, we added a 1/8 of polycarbonate protection, our vessel cruise at 30 knots and top at 38.. efficiency is the key, i do not like to run a generator but my beer must be almost frozen, eutectique systems are antiquated and inefficient, instead of cooling your food they freeze a solution that doesn’t like to be frozen, the second problem is the metering devices, TEV are less efficient than capillary tubes, 12/24 DC combined with AC 115/230 V AC is very practical for all on grid and off grid.. size is also the key, most eutectique are large and take valuable space, most sport fish boats cover the aluminum plates with a sheet of stainless..

Now that, as a house fridge would worry me. That’s a lot of exposed soft aluminium with delicate gas lines. Anyone puts something heavy or a little sharp in there and you’ve got a pretty high chance of a leak. Or even a long ocean passage on one tack causing something to rub through the plate.

This is why I think the eutectic tanks are not so bad for space. Once you’ve arranged adequate protection for those large aluminium evaporators you’ve lost as much or more space than you would from the eutectic tanks.[/QUOTE]

[GILow]

Originally Posted by Mabruteam

..., eutectique systems are antiquated and inefficient, instead of cooling your food they freeze a solution that doesn’t like to be frozen...


.. size is also the key, most eutectique are large and take valuable space, most sport fish boats cover the aluminum plates with a sheet of stainless..

Antiquated end inefficient? I’m using 50 AH@12v a day for a 230 litre fridge freezer. How is that antiquated or inefficient?

As for the stainless sheet, once you add that to protect the aluminium plates, you are right back to what the eutectic provides out of the box.

[170122]

After 35 years working on marine refrigeration my best option is air cool for reliability, 90% of the time the problems are related to the installation, we install the condenser air coil against a vent to create a suction of fresh air to cool the unit, not recirculating hot air inside the cabinet. this way the condenser never overheat and looses efficiency.
I have a large dual drawer freezer on my boat in the galley, a short 4 in round duct was designed to draw air from the cabin.



pr

Originally Posted by slug

Keel cooled temps can run hot when the boat is stationary in warm water
This would reduce energy efficiency

With air cooled it’s difficult to get rid of the hot air in some installations

Many times this means adding an addition fan to ventilate the space

More energy

[170122]

Freezing the solution inside the plates and the space it takes is antiquated, you want to put that energy directly to the food, stainless plates are made with inside with copper tubes with a lots of welds.. the efficiency on your box is based also on the insulation, opening on the top, and desired temperature.. for example for vegetables and a good insulation a good refrigerator will run 1.7 hours out of 24..
Fridges are mostly set at 40F, to maintain that temperature is an easy task, but to keep a freezer at 10 or 5 F is not the same story..

Originally Posted by GILow

Antiquated end inefficient? I’m using 50 AH@12v a day for a 230 litre fridge freezer. How is that antiquated or inefficient?

As for the stainless sheet, once you add that to protect the aluminium plates, you are right back to what the eutectic provides out of the box.

[170122]

This is why we do not use often Stainless, polycarbonate is practical and economical, airplane’s windshield are made with this material..
I remember been convinced that a Detroit 6-71 was an efficient engine..

Originally Posted by GILow

Antiquated end inefficient? I’m using 50 AH@12v a day for a 230 litre fridge freezer. How is that antiquated or inefficient?

As for the stainless sheet, once you add that to protect the aluminium plates, you are right back to what the eutectic provides out of the box.

[Uncle Bob]

Originally Posted by Mabruteam

I understand your dilemma, aluminum is week and could be perforated, we added a 1/8 of polycarbonate protection, our vessel cruise at 30 knots and top at 38.. efficiency is the key, i do not like to run a generator but my beer must be almost frozen, eutectique systems are antiquated and inefficient, instead of cooling your food they freeze a solution that doesn’t like to be frozen, the second problem is the metering devices, TEV are less efficient than capillary tubes, 12/24 DC combined with AC 115/230 V AC is very practical for all on grid and off grid.. size is also the key, most eutectique are large and take valuable space, most sport fish boats cover the aluminum plates with a sheet of stainless..

Now that, as a house fridge would worry me. That’s a lot of exposed soft aluminium with delicate gas lines. Anyone puts something heavy or a little sharp in there and you’ve got a pretty high chance of a leak. Or even a long ocean passage on one tack causing something to rub through the plate.

This is why I think the eutectic tanks are not so bad for space. Once you’ve arranged adequate protection for those large aluminium evaporators you’ve lost as much or more space than you would from the eutectic tanks.

[/QUOTE]


Pleased that you are happy with the product that you install in your boats but don't you think that perhaps your vessels are somewhat different to most of the membership here?
Must say that your claimed 1.7 hr / 24 hr runtime is extraordinarily good for any of the fridges you have pictured.

[GILow]

Originally Posted by Mabruteam

Freezing the solution inside the plates and the space it takes is antiquated, you want to put that energy directly to the food..

That is an illogical statement that does not acknowledge that the energy put into freezing the solution is not lost, but instead becomes a buffer to absorb thermal energy from the fridge interior over time. Regardless of the subtleties of phase changes etc, it is a closed system.

Words such as “antiquated” convey lots of emotion but no understanding of the physics and are bandied about without contributing anything of value to the discussion.

The space argument is still flawed. As I keep pointing out, the aluminium plates need protection, and once that is incorporated the volume used is remarkably similar.

I’m not selling anything here, but I am keen to keep the discussion factual and not emotive.

[GILow]

Originally Posted by Mabruteam

I remember been convinced that a Detroit 6-71 was an efficient engine..

Again, an emotive statement.

How does 50 AH@12 per 24 hours on a 230 litre fridge freezer compare to other systems?

If you are telling me that another system would use less power, fine, but remarks about old diesels are hardly relevant.

[RaymondR]

One of the schemes I pondered on was placing an exceptionally well insulated eutectic tank in a place in the boat where I had enough space for both tank and condensing unit and having a separate cold brine circulation system to transfer the waste heat from the refrigerator box to the eutectic ice/fluid mass.

The advantage of this was that it minimized space take up in the refrigerator section whilst allowing me a great range of options regarding the size and locating of the eutectic tank and the condensing unit.

I also pondered on using both brine and heat pipes and heat pipe loops for the transfer of the heat from the refrigerator box to the eutectic tank.

Since there was no head to overcome in the brine circulation system, only fluid friction losses, I considered using a magnetically coupled pump with a temperature controlled motor speed controller for temperature control of the refrigeration box. The heat pipe loop would be mechanically simpler in that it would not require a pump but some sort of solenoid valve is required to control the flow of the transfer fluid in the loop if thermostatic control of heat transfer is required.

It also appeared to be a good way to have multiple refrigerator boxes serviced by one single condensing unit and eutectic tank.

Due to the ridiculous levels of subsidies paid to home owners Australia has one of the largest take ups of roof top solar panels. The down side of this has been massive grid instability even to grid operators declining to accept power from solar farms. Since poly tanks, insulation and water are cheap I'm expecting the next great things to shock and amaze the home owning public are eutectic refrigeration and air conditioning with brine circulation distribution to be the next great CC/AGM fighting innovation.

[GILow]

Originally Posted by RaymondR

One of the schemes I pondered on was placing an exceptionally well insulated eutectic tank in a place in the boat where I had enough space for both tank and condensing unit and having a separate cold brine circulation system to transfer the waste heat from the refrigerator box to the eutectic ice/fluid mass.

The advantage of this was that it minimized space take up in the refrigerator section whilst allowing me a great range of options regarding the size and locating of the eutectic tank and the condensing unit.

I also pondered on using both brine and heat pipes and heat pipe loops for the transfer of the heat from the refrigerator box to the eutectic tank.

Since there was no head to overcome in the brine circulation system, only fluid friction losses, I considered using a magnetically coupled pump with a temperature controlled motor speed controller for temperature control of the refrigeration box. The heat pipe loop would be mechanically simpler in that it would not require a pump but some sort of solenoid valve is required to control the flow of the transfer fluid in the loop if thermostatic control of heat transfer is required.

It also appeared to be a good way to have multiple refrigerator boxes serviced by one single condensing unit and eutectic tank.

Due to the ridiculous levels of subsidies paid to home owners Australia has one of the largest take ups of roof top solar panels. The down side of this has been massive grid instability even to grid operators declining to accept power from solar farms. Since poly tanks, insulation and water are cheap I'm expecting the next great things to shock and amaze the home owning public are eutectic refrigeration and air conditioning with brine circulation distribution to be the next great CC/AGM fighting innovation.

Wow, you’ve clearly had too much time on your hands to ponder.

I’ve pictured what you describe in terms of the eutectic-in-the-keel approach and its good... but... how do you transfer the “cool” to the fridge? Aren’t we kinda back to the evaporator plate approach again?

Sort of related, friends just rebuilt their fridge box and it had the eutectic jacket built between the stainless steel fridge box liner and the insulation itself, which seemed clever to me. (Though, sadly, the old engine driven eutectic system was buggered, thankfully they have an Ozefridge tank inside the fridge box.)

As a South Australian I am brutally aware of the problems of grid instability created by alternative power sources, but I think SA has done the rest of the country a favour by being the canary in the gold mine. Interestingly, it seems one of the side benefits of Elon Musk’s great big battery pack up to the north here is that it is very good at re-stabilising the grid. I think SA has belatedly stumbled on a workable solution.

[RaymondR]

Originally Posted by RaymondR

One of the schemes I pondered on was placing an exceptionally well insulated eutectic tank in a place in the boat where I had enough space for both tank and condensing unit and having a separate cold brine circulation system to transfer the waste heat from the refrigerator box to the eutectic ice/fluid mass.

The advantage of this was that it minimized space take up in the refrigerator section whilst allowing me a great range of options regarding the size and locating of the eutectic tank and the condensing unit.

I also pondered on using both brine and heat pipes and heat pipe loops for the transfer of the heat from the refrigerator box to the eutectic tank.

Since there was no head to overcome in the brine circulation system, only fluid friction losses, I considered using a magnetically coupled pump with a temperature controlled motor speed controller for temperature control of the refrigeration box. The heat pipe loop would be mechanically simpler in that it would not require a pump but some sort of solenoid valve is required to control the flow of the transfer fluid in the loop if thermostatic control of heat transfer is required.

It also appeared to be a good way to have multiple refrigerator boxes serviced by one single condensing unit and eutectic tank.

Due to the ridiculous levels of subsidies paid to home owners Australia has one of the largest take ups of roof top solar panels. The down side of this has been massive grid instability even to grid operators declining to accept power from solar farms. Since poly tanks, insulation and water are cheap I'm expecting the next great things to shock and amaze the home owning public are eutectic refrigeration and air conditioning with brine circulation distribution to be the next great CC/AGM fighting innovation.

A cold brine or antifreeze in the loop would take up the heat from the contents of the refrigeration enclosure and carry it to the heat sink of the eutectic ice/liquid in the eutectic tank. Heat pipes are used where large amounts of heat need to be moved. They rely upon a volatile fluid evaporating and the rapid transfer of the vapor to a place where the heat can be radiated. The de-heated fluid then flows back to the hot end of the pipe.

[a64pilot]

I can explain why Richard keeps referencing a Eutetic system as one that is best used when there are alternative systems available, often Solar.
It’s because the other name for a Eutetic system, is HOLD OVER system, the tanks are a large thermal mass and the original designs for these systems were to take a whole lot of energy out of a large thermal mass (the tanks) and by using the properties of a Eutetic fluid being able to absorb a large amount of heat when they melt to “hold over” for a day or so, then when there was excess power available whether from running an engine or the middle of the Solar day when your batteries are in absorption, you take that excess power and freeze those plates back down.

You have a system that is capable of storing excess power when it’s available, assumption of course is that excess power is available at some time of the day.

However many eutectic systems aren’t really Eutetic systems anymore, meaning that the fluid never phase changes, so while they have “hold over” plates, they aren’t being used that way. Doesn’t really matter so long as it works and is energy efficient.

If you don’t use the energy storage of a “hold over” plate, then there in no technical advantage to the things, as was stated then they just take up more space in the box.

From a pure thermodynamics point of view it’s more efficient to remove heat from a mass with a thin plate evaporator as it’s doing so directly, a hold over plate, you remove heat from the fluid, and the fluid removes heat from the food and that is slightly less efficient than removing heat from the mass directly.

Now so far as this or that test that “proves” a Eutetic system is more energy efficient than a thin plate evaporator, the test is flawed, unless the operating conditions are the same, and I’m not talking box size, temp or insulation etc.
I’m talking system design, if one system requires the compressor to operate at a much lower COP due to its evaporator being undersized or at least smaller than the other system that is allowed to operate at a much higher COP, then of course the system that is operating at the higher COP will be more efficient and use less power, cause COP means coefficient of performance.

The difference however is not due to being Eutetic or thin plate, it’s the system is operating at a higher COP, due to the design differences between the two “identical” systems, in other words they are not identical.

But at the end of the day whether Eutetic or thin plate, the system that uses the least amount of energy will be the system that is properly designed, with properly matching components, that allows the compressor to operate at an efficient COP.