Another reason why Eutectic Plates are less desirable than Standard Refrigerator

[john61ct]

Originally Posted by newhaul

if you are trying to not use no dino juice why have an engine driven watermaker.
Go 12 volt and save fuel.

I did not mention engine-driven watermakers.

All the high gph ones are very high amps, can't realistically be powered off the batteries.

Anyway just an example, could be charging a big LFP bank with surplus available that way. Or washing clothes while cooking with induction, or or

[TJ D]

Originally Posted by john61ct

Do you really mean your refrigeration drew 40A while cycling?

So if for example it was cycling 1/3 of the time, it would consume 320AH per day??

Or did you just use the wrong units, and your system averaged 40AH per consumption?

That would be very efficient in hot weather.

The former seems crazy unsustainable to me, unless keeping a very large seafood catch frozen.

Yes, 40-45 amps draw. But, being a holding plate system, it wouldn't run that much. 2 hours/day or so in modertate temps, max no more than 3 hours/day in the tropics. This is for both fridge and freezer, about 5.5 cubic ft. each, fridge set at about 38, freezer at 0-5.

But, since we could hyper-cool the box during times of excess power, our actual draw on the batteries was not as simple as ampsXtime.

[alansmith]

john61ct, always enjoy your straight put analytical questions. Sounds like we are on similar paths. Where you located John?

You made mention of an evaporator/holding plate hybrid design...why not? I think i have come to the same conclusion that from a math point of view...which is the correct/only way to judge refridgeration ...that holding plates are the way to go.

My boat is a 30 foot Condor trimaran. I will be paneling up, Lithium up, and figure out whether to keep the Engle or go to modular component or OzePete or ????

Isn't it fun to go through all of these mental gyrations? I am digging it and learning little by little. Boat dollars just flying out of my mental wallet.

For my way of thinking and supported well in this and many threads...is that the thickness and capacity of the holding plates to keep the liquid in phase for such longer periods of time than the thin plate evaporators is a "no brainer".

Since i have plenty of real estate on the trimaran for panels i should have plenty of excess electrons for the battery bank. So, i was delighted to discover, new to my brain, the idea of charging the eutetics when there was surplus energy available with the ECO2 technology. How cool is that? (excuse the pun)

[a64pilot]

Originally Posted by john61ct

I literally cannot extract your intended meaning about compressors "producing energy".

They don’t actually produce energy, but point of fact, they usually do operate at greater than 100% efficiency, depending on how you look at it, but of course they are not perpetual motion machines.
See they move heat, not create it, so they can take X amount of power and move 2X worth of heat, where a pure resistance heater at 100% efficiency will take X amount of power and produce X amount of heat.
Remember these things move heat, they don’t produce cold

[a64pilot]

Originally Posted by john61ct

Questioning is good, not of anyone's integrity, but in the testing criteria and repeatability.

I certainly am already convinced of eutectic superiority in energy efficiency.

but **twice as efficient**, as a general rule without the free/excess energy, is much higher than others' test results.

I am trying to verify, clarify and understand is all.

See, what you speak of is not energy efficiency, but a way of storing excess energy, this ability to store excess energy when it’s available may mean less draw from your battery bank in a 24 hour period, but it may not be more efficient machine, just has the ability to store the excess when it’s available.
It may sound like arguing semantics, but it’s not, it is sort of like the amps per hour vs amp hour though.

Bottom line. For me, I don’t care really about efficiency, what I care about is how many AH do I pull from my bank in a 24 hour period.
I have 1000W Solar, and usually run my generator twice weekly, so usually every day I have excess power.

Now, I think to be fair to the thin plate guys, it should be pointed out that a larger battery bank is also an excellent way to store excess electrical power.
Just to throw another wrench into the argument.

[john61ct]

Yes. The reason why (in an ideal world, one day, For Science) I would like to settle the "pure efficiency" comparison issue, excluding the excess / free energy factor, is that the latter is **so** nebulous, unique to each install and varying according to too many outside factors.

In practice I agree eutectics can be the better choice, but box space and up front investment (as opposed to more bank AH) must also get factored in. As always "it depends".

[newhaul]

Originally Posted by john61ct

Yes. The reason why (in an ideal world, one day, For Science) I would like to settle the "pure efficiency" comparison issue, excluding the excess / free energy factor, is that the latter is **so** nebulous, unique to each install and varying according to too many outside factors.

In practice I agree eutectics can be the better choice, but box space and up front investment (as opposed to more bank AH) must also get factored in. As always "it depends".

when you add in the cost of additional battery capacity every few years. The initial cost of the holding plate system starts to save you money after say 10 years. For fla and less time for Lfp banks.

[a64pilot]

Originally Posted by john61ct

Yes. The reason why (in an ideal world, one day, For Science) I would like to settle the "pure efficiency" comparison issue, excluding the excess / free energy factor, is that the latter is **so** nebulous, unique to each install and varying according to too many outside factors.

As always "it depends".

I modified your quote above, but the second half of your quote is why I think that you will never get a true answer to which is more efficient, cause as you say, too many variables, and the answer is it depends.
I’m no expert by any means, and yet I think I could set up a test that would show what I wanted. I’m not saying anything funny was done, yet an bet it could be, it’s called marketing

I’d bet to actually optimize the efficiency of each system in say a 10cu ft box with R30 insulation and 10 lbs refrigerated food and 10lbs frozen food, with the freezer temp set to 0F and the fridge set to 40 F , the box in the shade and ambient temps a constant 80F would require very different systems with different sized components etc.
Immediately the naysayers would cry it wasn’t a fair test due to the different sized components.

The whole thing is a system with matched components. If you manufacturer it all, box included then you can really dial in a matched system for max efficiency.
However if you have to try to accept widely different sized boxes and widely different R values for insulation, then you have to have a flexible system that is often oversized in order to meet the out lier boxes demands.
You have to give up some efficiency to do so, but you have happy customers with 30 yr old ice boxes, cause their beer is cold and they have ice for drinks when they want it.


On edit a thin plate for example ought to have a wider thermostat set point say 6 or 7 degrees to cut down on compressor cycling. If you run a test that the set points are only 2degrees apart, your compressor will be cycling a whole lot.
However with a cold plate you can have your set points pretty close, ideally your set points allow the eutectic fluid to phase change, if you set your temps so that it doesn’t phase change then you will lose significant efficiency.

So, that is an easy way to either take advantage of a systems strengths or weaknesses.

I don’t see really how you could have a “fair”test, not really.

[jkleins]

Originally Posted by a64pilot

See, what you speak of is not energy efficiency, but a way of storing excess energy, this ability to store excess energy when it’s available may mean less draw from your battery bank in a 24 hour period, but it may not be more efficient machine, just has the ability to store the excess when it’s available.
It may sound like arguing semantics, but it’s not, it is sort of like the amps per hour vs amp hour though.

Bottom line. For me, I don’t care really about efficiency, what I care about is how many AH do I pull from my bank in a 24 hour period.
I have 1000W Solar, and usually run my generator twice weekly, so usually every day I have excess power.

Now, I think to be fair to the thin plate guys, it should be pointed out that a larger battery bank is also an excellent way to store excess electrical power.
Just to throw another wrench into the argument.

I am glad you said that last statement. I am having a real issue with the thinking that all cruisers have this "excess energy" problem. That may be a current issue with people who have AGM batteries that take a lot of energy to "top off" on a regular basis but that has to be seen as a problem of the past not the future.

Lithium and carbon foam already work for many of us to hold all the energy we can capture. I would rather spend the money on an extra battery to capture the energy then the $1000 or so on the more expensive holding plate. Don't get me wrong, I love holding plates (I had an old Glacier Bay plate that I loved) but in the current environment I would concentrate on capturing and storing all the energy you can before spending too much replacing a reasonably good refer with a more expensive holding plate.

If I was designing a new boat (or systems) I might do both but if I had to cut the costs I would do it on the refer side and beef up the battery and storage side since that energy can be used in a much more flexible manner.

Jim

[john61ct]

Originally Posted by a64pilot

I don’t see really how you could have a “fair”test, not really.

Well "my way", outlined in another thread:

Same boxes, loads and ambient temps, no excess energy.

5 target internal temps, from "cool beer" to "long-term frozen food safety"

Everything else wide open, design systems for energy efficiency, operating components and tuning can vary.

Those vendors selling both types can submit two units. Retail price F.O.B. published.

Start with warm load. Period 1 from start to target temp. Then P2, 48 hours maintaining. P3 half of load replaced with room temp, to target temp again.

Graph AH per hour, also average for each period.

[newhaul]

Originally Posted by john61ct

Well "my way", outlined in another thread:

Same boxes, loads and ambient temps, no excess energy.

5 target internal temps, from "cool beer" to "long-term frozen food safety"

Everything else wide open, design systems for energy efficiency, operating components and tuning can vary.

Those vendors selling both types can submit two units. Retail price F.O.B. published.

Start with warm load. Period 1 from start to target temp. Then P2, 48 hours maintaining. P3 half of load replaced with room temp, to target temp again.

Graph AH per hour, also average for each period.

john I did a rather extensive writeup a couple years ago on here concerning my cool blue system on my Spencer just look it up under my name and cool blue its there somewhere ( btw I'm not the one that started the threads. )

[a64pilot]

Originally Posted by john61ct

Well "my way", outlined in another thread:

Same boxes, loads and ambient temps, no excess energy.

5 target internal temps, from "cool beer" to "long-term frozen food safety"

Everything else wide open, design systems for energy efficiency, operating components and tuning can vary.

Those vendors selling both types can submit two units. Retail price F.O.B. published.

Start with warm load. Period 1 from start to target temp. Then P2, 48 hours maintaining. P3 half of load replaced with room temp, to target temp again.

Graph AH per hour, also average for each period.

You would likely find that the systems that cooled the food down in a relatively short time were your less efficient systems, as are the systems that can hold a very low temp
See my gut tells me the way to efficiency for a thin plate system is to size it so that it’s compressor is close to 100% duty cycle holding food cold.
That is sort of what is magic on these little newer compressors, their ability to run at 2000 or 3500 RPM.

However I’m at a loss to figure out what tells them to change speed assuming you have a normal mechanical thermostat with a resistor in line.


You may want to take a look at what is called a Stainless Lobster.
https://stainlesslobster.com
It seems to be a way to take advantage of excess energy, and to operate in a very efficient manner when the bank is not being charged. It has user adjustable set points so that you can reduce the temp set point and kick the RPM up to high above a set voltage, and increase set point temp and slow compressor down to 2000 RPM whenever the voltage is below the point you set that corresponds to your bank being charged.

It also allows you to set both the turn on and off set points for the compressor.

Essentially it allows you to “tune” your fridge

[skipgundlach]

Well, I've had yet another confirmation of why I hate web access; I lost my internet just as I was posting a comment, which I'll try to reproduce, as it's now gone...

A previous poster bragged on using his aux to do the eutectic charging. We're a sailboat, so we don't - literally - run the aux unless we have to for propulsion. I removed a honking great-big compressor, the AC compressor, and the dual-circuit holding plates in our double-decker coffin (our boats' cold box was 19CF), and started from scratch.

That initial decision was to install a Frigoboat largest-available evaporator and BD50 compressor, using a keel cooler. That installation worked a treat for us, with our then-current state-of-the-art solar and wind. The failure of that system, the cause being now cured by Veco, is well documented on CF; our system was dead, however. We went back with a SeaFrost evap system, that installation also having been extensively explored on CF.

However, our battery and solar upgrade of late (see "Flying Pig's Excellent Adventure" here in CF) has made it so that our chief concern is whether we have to change the Mobil 1 (current TV ads promise annual/20000 hour oil changes in cars and trucks) by calendar, rather than by hours, as the 100 hour change interval, at our current pace, is some years in the future, or the survivability of the gas in the gerry cans.

As to our usage, we don't run the aux other than for propulsion or anchoring. Nigel Calder did a seminar on the efficacy and cost efficiency of watt generation at one of the SSCA annual meetings a while back. At that time, by far the most expensive was any use of the aux for charging (regardless of what you had hooked up to it), followed closely by any stand-alone diesel genset. Tied, nominally, for 3rd, depending on location and cost of acquisition, was solar, wind and Honda suitcase gensets.

In our case, our upgrade literally changed our lives, and our otherwise very amp-hungry refrigeration is now very cold without our having to run the Honda - let alone our aux - to keep up with the wattage.

If you're a power boat, by all means use the aux to charge your cold plates when you're under way. But what will you do (other than have to run it when you're anchored)?

The choice of eutectics or evaps is still up in the air, with some of my best friends making and selling eutectics despite my not having bought their gear. For myself, having had some exposure to holding plates, I prefer the relatively constant temperature of an evaporator with a circulation fan; one (well the FB was one; the Sea Frost is 3 interconnected) compressor and box provides very closely regulated temperatures in both the reefer (via spillover and fan, and circulation fan) and freezer (with circulation fan)...

[kmacdonald]

The only reason a eutectic plate system should even be considered is if you ALREADY have excess energy available during certain time periods. Adding solar to get to that point would not be cost effective. Fact is that, evaporator plate refrigeration is more energy efficient, takes less space in the box, costs significantly less. Thats why it's used in just about every home in America. Energy consumption is HIGHLY functional on ambient temperature, box temperature, and proper system sizing and setup that any so called "experiment" by sales staff should be given all the credibility it deserves------NONE.

[newhaul]

Originally Posted by kmacdonald

The only reason a eutectic plate system should even be considered is if you ALREADY have excess energy available during certain time periods. Adding solar to get to that point would not be cost effective. Fact is that, evaporator plate refrigeration is more energy efficient, takes less space in the box, costs significantly less. Thats why it's used in just about every home in America. Energy consumption is HIGHLY functional on ambient temperature, box temperature, and proper system sizing and setup that any so called "experiment" by sales staff should be given all the credibility it deserves------NONE.

actually the home units have nothing to do with efficiency they have to do with how cheaply it can be manufactured. If they were wanting efficiency they would have kept the condenser coils on the back and not have incorporated them into the case for aesthetic reasons.
I installed a cool blue system and 200 watts of mono panels to run it. Well the new owner is living on the hook and the system is doing just great. 200 supports the fridge and all of the other power needs on the 42 ft Spencer.
The fact is I installed the solar must to run the fridge . Well it wouldn't run an Crap plate system . I installed one on a customers boat . But with 250 watts solar and it ain't cutting the mustard. ( I recommended a holding plate system he didn't want to spend the extra 500 bucks. ) he ended up having to purchase a portable generator to keep up with his refer demands.