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Old 16-04-2018, 02:57   #1
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Eutectic refrigeration for marine use

There has been a lot said here regards Eutectic marine Refrigeration but mostly opinion and mostly without any basis. This thread is an attempt to explain the eutectic refrigeration system and to present the results of a direct comparison trial conducted between a eutectic stainless steel system and a cyclic aluminium cold plate system used in an identical application.

But first:
1. What is meant by Eutectic refrigeration: Eutectic refrigeration systems use a refrigeration condensing unit much like any other system. The difference is that a eutectic system involves refrigerating a storage tank that contains a solution that freezes solid to a predetermined temperature. (centigrade). The eutectic system benefits from the ‘phase change’ of a stored medium and the enormous energy storage this latent heat application provides

2. To Explain: We all know that a cold drink with ice in it will stay cold and drinkable at a constant temperature while the ice remains, but will warm rapidly once the ice thaws.
The ice is an example of the eutectic principle. The ice absorbs relatively huge amounts of heat from the drink, causing the drink to remain cold, while it thawed from a solid back to a liquid. (Phase changing)
A phase change medium or eutectic solution is stored in the stainless steel eutectic tank or plate within the fridge cabinet and acts like a renewable ice block, freezing solid during the refrigeration run cycle and thawing during off periods, and all the time maintaining a constant fridge cabinet temperature just like the ice did for the cool drink!

3. How does it work:
A digital thermostat probe located within the eutectic solution, causes the compressor to run when it senses that the solution has thawed. The compressor runs for a long period to refreeze the solution solid virtually storing thermal energy for cooling in advance. Hold over refrigeration, because once the mass is re-frozen it holds the cabinet at the desired temperature for many hours and often a day or so in cooler climates.

4. So where is the benefit: Phase Change occurs when we freeze a solution solid by removing its heat, or as it thaws into a liquid again while it absorbs heat.
Other products such as a thin aluminium evaporator plate systems can also absorb and dissipate thermal energy (heat) but when a relatively large volume of solution is used as in the eutectic plate and it is allowed to freeze solid on the refrigeration run cycle, then thaw during the off cycle, a massive amount of stored thermal energy is in play.
By comparison with a thin aluminium cold plate, the first and most obvious advantage the eutectic system has is its far greater mass and therefore thermal hold-over storage capacity. (A thin 2mm thick slice of ice will disappear much quicker than a 60mm thick block would)
But this thermal storage advantage pales into insignificance compared to the other unique benefit that the eutectic system phase change phenomenon delivers. This is called ‘Latent heat’. It effectively multiplies the eutectic thermal storage capacity of the medium byup to 80 times (yes eighty times) providing huge hold-over periods where the unit stays off for many hours even days in cooler times.

5. So why use a Eutectic system:
A: Weight. The total weight of an operating eutectic system is less than half the weight of the batteries that would otherwise be required to power up a cyclic cold plate fridge unit to provide the same cooling.
B: Power efficiency. A eutectic system will use much less power to do the same job as a cyclic system. (See test results and reasons why following below).
C: Product temperature pull-down. Warm products added to the cabinet have the benefit of the stored eutectic mass to reduce the temperature of warm product faster, not solely relying on the refrigeration unit’s capacity at the time.
D: Some systems can be set to refreeze the eutectic mass when power is abundant reducing or eliminating battery consumption.
E: Doesn’t require a battery power supply 24 /7. Refreeze can often be when it best suits available power.

6: Refrigeration with NO battery drain. Is it possible?
Because a eutectic system usually only needs one continuous two to three hour run per day, (in average ambient) devices like the Ozefridge ECO2 will cause this run to occur when power is abundant eliminating the need to draw any battery power at all at other times! (Abundant power would be when batteries are fully charged and solar or whatever is being wasted, for example!)

7: What causes a eutectic system to be so efficient?
Firstly, given a cabinet to refrigerate, as in this test, the amount of heat to be removed (measured in watts) is exactly the same regardless of the refrigeration method used. Therefore it gets down to the efficiency of the refrigeration system's operation. .

There are two main reasons why the eutectic systems are much more power efficient.

The first relates to the refrigeration systems CoP (Co-efficiency of Performance)
To explain: COP is a factor indicating how much heat is removed relative to electrical energy consumed. A system with a COP of say 1.13 removes 1.13 watts of heat for each watt of electrical energy consumed. (Similar to miles per gallon, and the bigger the number the greater the efficiency!)
This 1.13 COP would be typical of the cyclic fridge system as its evaporator would mostly run at -23C or colder while refrigerating.
This 1.13 COP rate is very inefficient compared to the eutectic system which would have a much better COP of 1.95. Far more heat removed per watt of battery power consumed!
(The lower the temperature a refrigeration system’s evaporator runs at, the less efficient the system is. Running a system on with a low COP is very false economy)
Secondly, motor start up inefficiencies. All electric motors consume excess energy while providing little benefit during start up. This waste of energy is obviously far less with a eutectic system as it only starts once or twice a day instead of 20 to 60 times as for a cyclic system. This is the greatest cause of inefficiency and would be even worse if compressors didn’t have soft start motor driver modules like those in this test!

8: Power consumption test method and results:
This test was performed with a domestic 150 litre freezer (70mm walls) which had its compressor etc., removed, so basically and empty cabinet.
Two identical Ozefridge condensing units set to operate as air cooled only.
One condensing unit was coupled to a 400mm x 400mm aluminium Cyclic cold plate, the other was couple to an Ozefridge mid range eutectic SS plate 400mm x 330mm overall.
During a two month period each system was operated consecutively to maintain the cabinet at between 2C and 4C controlled via the same digital thermostat. The run period for each system was in 7 to 8 day blocks each consecutively. The ambient temperature which ranged from 10C to 42C maximum was similar for both systems.
Power consumption was recorded and resulted in the cyclic aluminium system using approx twice as much power as the eutectic system to do exactly the same job!
Note: A similar test since in even hotter conditions saw the consumption benefit of the eutectic system reduced, but still quite significant. Also operating as a freezer will also see an efficiency advantage with Eutectic but not nearly as extreme as when operating as a refrigerator like in the test. (The trials were done fairly and the test equipment retained at Ozefridge as is, so if anyone wishes they are welcome to inspect, by appointment.)

9: Other aspects of a Eutectic system:
Eutectic plates are usually 318 grade stainless, not soft aluminium or copper therefore much less likely to be damaged / punctured, easy to clean and don’t grow ‘nasties’ than can taint/ contaminate food.
Negatives:
Initial temperature pull down of a eutectic system is slower than a cyclic system. Expect first run of a DC powered eutectic system to be 3 to 4 hrs.
A eutectic plate takes up more cabinet space than a cyclic plate.
A eutectic system obviously costs more than a cyclic system.

Pictures of the testing.
The first picture is of the 150 litre cabinet used in the test with identical air cooled Ozefridge refrigeration units. One unit refrigerates a cyclic aluminium cold plate and the other a mid size Ozefridge Eutectic cold plate. (see: second picture of cabinet interior)
A monitoring, data logging station was connected to each system. (See third picture)

The final picture is of a spread sheet colour coded to indicate which system was refrigerating the cabinet and the daily watts consumed.
It can be seen that the cyclic system (green) benefited from ‘hold-over’ of the eutectic plate for its first days consumption for each of its run periods.
Yet even with this advantage it still consumed twice as much power as the eutectic system.
It’ a no-brainer if power consumption is a consideration on board!

Click on picture to enlarge:

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Conclusion:
This trial was conducted correctly and in average conditions.
At Ozefridge we manufacture both Cyclic and Eutectic systems but recommend eutectic in most cases for reasons that must be obvious.
We welcome visitors to inspect our test system.

We always could calculate the power economy that operating a eutectic system with a much higher COP would provide as that is simple indisputable maths, but calculating the loss of efficiency upon compressor start up was not feasible or accurate.
Hence this test which even surprised us.
We expected the cyclic system to use say 40 to 50% more but double!
The biggest area of inefficiency is the excessive daily start ups and when we consider that the test refrigeration units had ‘soft start’ motor driver modules, and therefore more power frugal, how much worse would the cyclic systems consumption be with the old DOL modules!

Cheers OzePete
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Old 16-04-2018, 03:17   #2
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Re: Eutectic refrigeration for marine use

Thanks Peter for taking the time to test and compare.

Trying to understand why in Tropical conditions, the benefits are less?

Is that because the cold plate system runs longer with not so many startups?
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Old 16-04-2018, 04:15   #3
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Re: Eutectic refrigeration for marine use

Quote:
Originally Posted by Pelagic View Post
Thanks Peter for taking the time to test and compare.

Trying to understand why in Tropical conditions, the benefits are less?

Is that because the cold plate system runs longer with not so many startups?
Hi Pelagic,
Yes once the temperature was constantly in the 35C to 45C range the difference in consumption was less. The Cyclic system was using approx 70% more power than the Eutectic while during the test reported the Cyclic system used greater than 100% more power.
We believe the difference was due to two issues and you have mentioned one being that the cyclic system had longer run cycles therefore less inefficient start ups per day. The second issue is that the eutectic plate we used was our mid sized model being 40 x 33 x 6 and should have been the larger 53 x 35 x 6 plate to suit the hotter conditions. The larger eutectic plate would provide slightly better efficiency in both scenarios.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems
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Old 16-04-2018, 05:22   #4
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Re: Eutectic refrigeration for marine use

This is an interesting post and makes me question a descision I just made on my boat.

Our boat is equipped with a "Cold Machine" freezer system (a CU-95 and VD-16). Ever since we have owned her, the CU-95 has been "jumped" for continous operation. The freezer draws 4A all the time and never cycles.

Recently I purchased an electronic control (exactly like the ones in your pictures, STC-8080H). I planned to wire it in and put the system back to cyclic use. However, now I'm wondering if the gains would be worth it.

Right now the freezer is AMAZING. It froze a whole turkey at Christmas, here in the Caribbean. So if wiring in the controller only gains me 10-12Ah over the night, it might not be worth it.

Sorry if this derails the topic.. but maybe you are on to something with the whole cyclic thing.
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Old 16-04-2018, 05:41   #5
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Re: Eutectic refrigeration for marine use

Quote:
Originally Posted by travellerw View Post
This is an interesting post and makes me question a descision I just made on my boat.

Our boat is equipped with a "Cold Machine" freezer system (a CU-95 and VD-16). Ever since we have owned her, the CU-95 has been "jumped" for continous operation. The freezer draws 4A all the time and never cycles.

Recently I purchased an electronic control (exactly like the ones in your pictures, STC-8080H). I planned to wire it in and put the system back to cyclic use. However, now I'm wondering if the gains would be worth it.

Right now the freezer is AMAZING. It froze a whole turkey at Christmas, here in the Caribbean. So if wiring in the controller only gains me 10-12Ah over the night, it might not be worth it.

Sorry if this derails the topic.. but maybe you are on to something with the whole cyclic thing.
Hi Traveller,
What you have is not a eutectic system nor a cold plate cyclic system, it is a forced air- cross finned evaporator!!
What are the interior dimensions of your cabinet?
OzePete
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Old 16-04-2018, 06:29   #6
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Re: Eutectic refrigeration for marine use

Pete,
Fantastic post!!!!

A couple of questions:
1) I assume that both systems use Expansion Valves?
2) Have you done the same tests for freezer temps (-20c box temp / -23c evap temp)?
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Old 16-04-2018, 07:08   #7
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Re: Eutectic refrigeration for marine use

Quote:
Originally Posted by OzePete View Post
Hi Traveller,
What you have is not a eutectic system nor a cold plate cyclic system, it is a forced air- cross finned evaporator!!
What are the interior dimensions of your cabinet?
OzePete
Yes I have done some reading on our system. It always surprises guests when they open our freezer and see the inside. Most have never seen anything like it.

Like I said it works fantastic. If you put 10 beer in front of the fan they will be drinkable cold in about 8-10 min. However, I wonder how much power I'm wasting because it runs all the time. It was the PO that jumped it to run %100 when the thermostat failed in Cuba and they couldn't get a replacement.

The cabinet is 14(wide) X 24(long) X 23(deep) (all inches). I don't know the R value of the insulation, but the walls are 2.5 inches thick.
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Old 16-04-2018, 09:02   #8
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Re: Eutectic refrigeration for marine use

I've only just started reading this article, but it looks really good. It would have been very interesting to see a internal temperature graph comparison between the two systems over the 30 days.


Allan.
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Old 16-04-2018, 09:23   #9
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Re: Eutectic refrigeration for marine use

It seem you do make a good product, so much so, I want to order one. The problem is your claim against reality of operation and power out comes it seems are too conservative when it comes to boat installations.

Two life long friends who are sail boat owners have installed your system in the Sydney and Pittwater area. They both complained, Unlike your static test, they discovered in real life boat operation your systems are very taxing on available power required to keep them running so they can't use them as required.

One mate has now bought a small 12 volt freezer instead of using the ozeFrig he installed to remedy the problem, his plan is only to use your fridge when he is motoring long distances. The other life friend tells me it takes 80 Ah 24 hours to keep his system running. That is 6.6 Ah per hour.

This is very different to your static test of 12 amp in 24 hours. it seems that the fridge in the photo you presented also had poor instillation as well?

For my part I have a 135 liter eutectic fridge that was run by engine AC compressor. It failed - My plan was to install your system and do away with the engine driven compressor. Now I use the fridge as a storge box for general food dry goods storage. and run a Evakool 45 liter portable fridge freezer instead also only 14 hours a day as it is well insulated fiberglass ice box construction.

I wish it was so, but there is no getting around the law of physics. when you want a cooled beer in the tropics.

Kryg






Quote:
Originally Posted by OzePete View Post
There has been a lot said here regards Eutectic marine Refrigeration but mostly opinion and mostly without any basis. This thread is an attempt to explain the eutectic refrigeration system and to present the results of a direct comparison trial conducted between a eutectic stainless steel system and a cyclic aluminium cold plate system used in an identical application.

But first:
1. What is meant by Eutectic refrigeration: Eutectic refrigeration systems use a refrigeration condensing unit much like any other system. The difference is that a eutectic system involves refrigerating a storage tank that contains a solution that freezes solid to a predetermined temperature. (centigrade). The eutectic system benefits from the ‘phase change’ of a stored medium and the enormous energy storage this latent heat application provides

2. To Explain: We all know that a cold drink with ice in it will stay cold and drinkable at a constant temperature while the ice remains, but will warm rapidly once the ice thaws.
The ice is an example of the eutectic principle. The ice absorbs relatively huge amounts of heat from the drink, causing the drink to remain cold, while it thawed from a solid back to a liquid. (Phase changing)
A phase change medium or eutectic solution is stored in the stainless steel eutectic tank or plate within the fridge cabinet and acts like a renewable ice block, freezing solid during the refrigeration run cycle and thawing during off periods, and all the time maintaining a constant fridge cabinet temperature just like the ice did for the cool drink!

3. How does it work:
A digital thermostat probe located within the eutectic solution, causes the compressor to run when it senses that the solution has thawed. The compressor runs for a long period to refreeze the solution solid virtually storing thermal energy for cooling in advance. Hold over refrigeration, because once the mass is re-frozen it holds the cabinet at the desired temperature for many hours and often a day or so in cooler climates.

4. So where is the benefit: Phase Change occurs when we freeze a solution solid by removing its heat, or as it thaws into a liquid again while it absorbs heat.
Other products such as a thin aluminium evaporator plate systems can also absorb and dissipate thermal energy (heat) but when a relatively large volume of solution is used as in the eutectic plate and it is allowed to freeze solid on the refrigeration run cycle, then thaw during the off cycle, a massive amount of stored thermal energy is in play.
By comparison with a thin aluminium cold plate, the first and most obvious advantage the eutectic system has is its far greater mass and therefore thermal hold-over storage capacity. (A thin 2mm thick slice of ice will disappear much quicker than a 60mm thick block would)
But this thermal storage advantage pales into insignificance compared to the other unique benefit that the eutectic system phase change phenomenon delivers. This is called ‘Latent heat’. It effectively multiplies the eutectic thermal storage capacity of the medium byup to 80 times (yes eighty times) providing huge hold-over periods where the unit stays off for many hours even days in cooler times.

5. So why use a Eutectic system:
A: Weight. The total weight of an operating eutectic system is less than half the weight of the batteries that would otherwise be required to power up a cyclic cold plate fridge unit to provide the same cooling.
B: Power efficiency. A eutectic system will use much less power to do the same job as a cyclic system. (See test results and reasons why following below).
C: Product temperature pull-down. Warm products added to the cabinet have the benefit of the stored eutectic mass to reduce the temperature of warm product faster, not solely relying on the refrigeration unit’s capacity at the time.
D: Some systems can be set to refreeze the eutectic mass when power is abundant reducing or eliminating battery consumption.
E: Doesn’t require a battery power supply 24 /7. Refreeze can often be when it best suits available power.

6: Refrigeration with NO battery drain. Is it possible?
Because a eutectic system usually only needs one continuous two to three hour run per day, (in average ambient) devices like the Ozefridge ECO2 will cause this run to occur when power is abundant eliminating the need to draw any battery power at all at other times! (Abundant power would be when batteries are fully charged and solar or whatever is being wasted, for example!)

7: What causes a eutectic system to be so efficient?
Firstly, given a cabinet to refrigerate, as in this test, the amount of heat to be removed (measured in watts) is exactly the same regardless of the refrigeration method used. Therefore it gets down to the efficiency of the refrigeration system's operation. .

There are two main reasons why the eutectic systems are much more power efficient.

The first relates to the refrigeration systems CoP (Co-efficiency of Performance)
To explain: COP is a factor indicating how much heat is removed relative to electrical energy consumed. A system with a COP of say 1.13 removes 1.13 watts of heat for each watt of electrical energy consumed. (Similar to miles per gallon, and the bigger the number the greater the efficiency!)
This 1.13 COP would be typical of the cyclic fridge system as its evaporator would mostly run at -23C or colder while refrigerating.
This 1.13 COP rate is very inefficient compared to the eutectic system which would have a much better COP of 1.95. Far more heat removed per watt of battery power consumed!
(The lower the temperature a refrigeration system’s evaporator runs at, the less efficient the system is. Running a system on with a low COP is very false economy)
Secondly, motor start up inefficiencies. All electric motors consume excess energy while providing little benefit during start up. This waste of energy is obviously far less with a eutectic system as it only starts once or twice a day instead of 20 to 60 times as for a cyclic system. This is the greatest cause of inefficiency and would be even worse if compressors didn’t have soft start motor driver modules like those in this test!

8: Power consumption test method and results:
This test was performed with a domestic 150 litre freezer (70mm walls) which had its compressor etc., removed, so basically and empty cabinet.
Two identical Ozefridge condensing units set to operate as air cooled only.
One condensing unit was coupled to a 400mm x 400mm aluminium Cyclic cold plate, the other was couple to an Ozefridge mid range eutectic SS plate 400mm x 330mm overall.
During a two month period each system was operated consecutively to maintain the cabinet at between 2C and 4C controlled via the same digital thermostat. The run period for each system was in 7 to 8 day blocks each consecutively. The ambient temperature which ranged from 10C to 42C maximum was similar for both systems.
Power consumption was recorded and resulted in the cyclic aluminium system using approx twice as much power as the eutectic system to do exactly the same job!
Note: A similar test since in even hotter conditions saw the consumption benefit of the eutectic system reduced, but still quite significant. Also operating as a freezer will also see an efficiency advantage with Eutectic but not nearly as extreme as when operating as a refrigerator like in the test. (The trials were done fairly and the test equipment retained at Ozefridge as is, so if anyone wishes they are welcome to inspect, by appointment.)

9: Other aspects of a Eutectic system:
Eutectic plates are usually 318 grade stainless, not soft aluminium or copper therefore much less likely to be damaged / punctured, easy to clean and don’t grow ‘nasties’ than can taint/ contaminate food.
Negatives:
Initial temperature pull down of a eutectic system is slower than a cyclic system. Expect first run of a DC powered eutectic system to be 3 to 4 hrs.
A eutectic plate takes up more cabinet space than a cyclic plate.
A eutectic system obviously costs more than a cyclic system.

Pictures of the testing.
The first picture is of the 150 litre cabinet used in the test with identical air cooled Ozefridge refrigeration units. One unit refrigerates a cyclic aluminium cold plate and the other a mid size Ozefridge Eutectic cold plate. (see: second picture of cabinet interior)
A monitoring, data logging station was connected to each system. (See third picture)

The final picture is of a spread sheet colour coded to indicate which system was refrigerating the cabinet and the daily watts consumed.
It can be seen that the cyclic system (green) benefited from ‘hold-over’ of the eutectic plate for its first days consumption for each of its run periods.
Yet even with this advantage it still consumed twice as much power as the eutectic system.
It’ a no-brainer if power consumption is a consideration on board!

Click on picture to enlarge:

Attachment 168203 Attachment 168202

Attachment 168204 Attachment 168201


Conclusion:
This trial was conducted correctly and in average conditions.
At Ozefridge we manufacture both Cyclic and Eutectic systems but recommend eutectic in most cases for reasons that must be obvious.
We welcome visitors to inspect our test system.

We always could calculate the power economy that operating a eutectic system with a much higher COP would provide as that is simple indisputable maths, but calculating the loss of efficiency upon compressor start up was not feasible or accurate.
Hence this test which even surprised us.
We expected the cyclic system to use say 40 to 50% more but double!
The biggest area of inefficiency is the excessive daily start ups and when we consider that the test refrigeration units had ‘soft start’ motor driver modules, and therefore more power frugal, how much worse would the cyclic systems consumption be with the old DOL modules!

Cheers OzePete
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Old 16-04-2018, 10:48   #10
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Re: Eutectic refrigeration for marine use

[QUOTE=kryg;2616540..... The other life friend tells me it takes 80 Ah 24 hours to keep his system running. That is 6.6 Ah per hour.
Kryg[/QUOTE]

80Ah a day is 3.3A an hour not 6.6A.

I don't know if your life long friends are using the units as fridges or freezers. But if they are freezers and with standard production boat insulation, 80Ah per day is pretty damn good.

Still not the "...static test of 12 amp in 24 hours", but still well above most.
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Old 16-04-2018, 11:31   #11
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Re: Eutectic refrigeration for marine use

Haven't eutectic systems been around for awhile? They are common on refrigerated trucks. We have a two truck-plate system in our '82 boat that have two different eutectic freezing point salt solutons, one for refrigeration and one for freezer. The compressors are common supermarket types. We run them for 30-40 minutes once or twice a day. A bag of ice lasts for 1 1/2 weeks. Though they are 120VAC, there's no reason why 12VDC motors couldn't run the compressors.

Other than new electronics, why would I expect to have an improvement with your system?
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Old 16-04-2018, 12:01   #12
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Re: Eutectic refrigeration for marine use

I could not see any food in the box in the picture!
You MUST have had something in the box to simulate a "standard" food load, otherwise the compressor cycling frequency of the less efficient system would be much higher than normal operation.
I can describe two ways the eutectic system improves efficiency.
1. when a compresssor starts, it does no cooling at first, as it begins to change the pressures in the refrigerant circuit. As time passes, on the order of second or even several minutes, the cooling increases to its full capacity.
During this start-up period, the power used may be lower, but less cooling is done so the efficiency (COP) is very low. By reducing the number of starts per day, a significant power reduction results. This is why refrigerator testing is done with a water load inside the cabinet. Changing the thermostat to a wider dead band can save power by reducing cycling.

What the eutectic system ALSO does is decrease the lift, the pressure difference between the evaporator and the condenser. with the aircooled evaporator, the air right next to the plate is MUCH colder than the eutectic fluid, resulting in a lower refrigerant evaporator pressure. The compressor runs longer to move the same amount of heat.
So I ask again, was there food or water on the box during testing?
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Old 16-04-2018, 15:25   #13
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Re: Eutectic refrigeration for marine use

Hi All,
I tend to agree there would be an external heat load but without the product load the cold plate unit would seem likely to start/stop more frequently. No "thermal inertia".
I think the stainless case of the eutectic plate is a poor conductor of heat and slows the whole process. Why not aluminium?

The Engine driven compressor (open drive) eutectic was as far as I know introduced to take advantage of the fast "pull down" of the large compressor driven by the engine. In that system it is only necessary to run the compressor once or twice a day for a short time maybe as little as 10 minutes. (In those days there was no 12V compressors, no investors and only car aircon compressors. But they are expensive to build and maintain and regular checking and maintenance is important. I have an open drive eutectic system and if I were to replace it I would go for a cold plate 12V system simply because it will give me the fastest pull down. For day cruising (out for the day) with the family that's all you need. But I love the fast pull down of the current system.

I don't want to be waiting around while a 50W compressor tries to freeze 2L of water. (Before it does anything else). My guess it would take 2 1/4 hrs to get that eutectic plate from 15C to 0C then how long to freeze?

I think that a eutectic 12 V system of less than 100W refrigeration capacity impractical. Unless you can load it with precooled or even refrozen product.
It's a lot of work to go out and prove, in a Lab, any of this.

These days with the improvements in solar power the 12v system is much more user friendly.

I appreciate the effort that has gone into the article. Thankyou.

Cheers Woody
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Old 16-04-2018, 15:51   #14
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Re: Eutectic refrigeration for marine use

Quote:
Originally Posted by missourisailor View Post
80Ah a day is 3.3A an hour not 6.6A.

I don't know if your life long friends are using the units as fridges or freezers. But if they are freezers and with standard production boat insulation, 80Ah per day is pretty damn good.

Still not the "...static test of 12 amp in 24 hours", but still well above most.
Thanks, I stand corrected,at 3.3 Ah. I'm not so good on night watch!

Never the less, I agree that 80 Ah is a good outcome but than one needs to replace that power which has repercussions. Say if you have a house AGM battery bank like myself of 500 Ah. You will need to recover the used 80 Ah, this it is a significant issue, as battery manufacture recommend that one can't discharged more then say 60% max for say AGM in effect AGM battery's should not be discharged more the 30% if you want to keep the battery manufactures claimed 10 year life and not shorten it to say 3 to 4 years through recycling.

That cold beer you enjoy, is paid for by a power recovery of replacing nearly 1/3rd of your usable battery per day that is not using any other boating equipment to run your boat like nav lights autopilot radar boats computers. This is only if your battery are are relatively new. As most battery can only be recharged up to 85 - 90% capacity. Meaning your battery bank of 500 Ah is really has 450 Ah's at 90% fully topped up. Discharge max should only be say 40% max so in this case what is available is a 180 Ah. - 80Ah for the eutectic 12 volt fridge. You have only 100Ah to run your boat experience shows, that in reality your battery bank has far less available power, depending on your battery age and condition and user abuse.

Your beer is going to cost you big time, in some form of energy generation to replace that fridge power each day through recharging. This is the main issue for most sailors who use their boats more then say weekend or day sailing.
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Old 16-04-2018, 21:18   #15
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Re: Eutectic refrigeration for marine use

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Originally Posted by Locquatious View Post
Haven't eutectic systems been around for awhile? They are common on refrigerated trucks. We have a two truck-plate system in our '82 boat that have two different eutectic freezing point salt solutons, one for refrigeration and one for freezer. The compressors are common supermarket types. We run them for 30-40 minutes once or twice a day. A bag of ice lasts for 1 1/2 weeks. Though they are 120VAC, there's no reason why 12VDC motors couldn't run the compressors.

Other than new electronics, why would I expect to have an improvement with your system?
Hi Locquatious.
Just to clarify, you use a "salt solution" in your eutectic system?
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