Refrigeration - Evaporator vs. Holding Plate

[john61ct]

Actually I've lived for decades in communities where maybe a dozen households out of millions had refrigeration, and have gone without for more than a few years at a time myself.

Let's not forget even clean running water is a luxury in most of the world.

And one missing for millions of people in the US.

[Richard Kollmann]

Originally Posted by SV THIRD DAY

Exactly....the KEY in my opinion is the TXV. Sea Freeze of America out of WA has been making flat plate evaporators with TXV for about 20yrs now.
"There is nothing new under the sun", or in Refrigeration 101.

That's where a lot of the confusion also comes into play.
The different models and approaches are often lumped together and debated as the same thing, when they are not.
The 4 basic type of systems are:

Thin Evaporator With Critical Orifice
Thin Evaporate with TXV
Hold Over plate with Critical Orifice
Hold Over plate with TXV

Arguments in favor and against all the possible combinations can and will be made from the vantage point of efficiency, price and customer service and serviceability. This ain't the USSR 1970, we have more than one choice of beer on the shelf.

The one things I know is that people who say they can cruise without refrigeration are crazy...don't trust them with your Cat.

Rich, You are correct the only way to have a true good freezer is when eutectic plates or an evaporator surrounds the frozen product. In order to solve the problem of one eutectic plate in a freezer I designed and sold a group of small convection evaporators named freeze Blasts that were connected between TXV and eutectic plate.

[newhaul]

Originally Posted by john61ct

Actually I've lived for decades in communities where maybe a dozen households out of millions had refrigeration, and have gone without for more than a few years at a time myself.

Let's not forget even clean running water is a luxury in most of the world.

And one missing for millions of people in the US.

yes but if you don't have to live without it why would you ?

[missourisailor]

Just because I’m a sucker for punishment, here are some more numbers for people to argue about.

From the Danfoss technical papers, a BD35 and/or BD50 w/ a std electronic unit (not the BD50 w/ high current electronic unit), has a peak current draw just under 13A during startup.
The start up cycle last for about 350ms, including 225ms for alignment.

Using my non calibrated eye ball, 7.5A seems to be a good average current draw for the whole 350ms start up cycle.

Some simple math tells us that during a normal start up, 0.0438A is consumed.
60sec/7.5A=0.125A per sec.
1/.350=2.85
0.125A/2.85=0.0438A

Now Rich has stated that using a box w/ R30 insulation, his holding plate systems will cycle 4 times in a 24hour period. I think this is kind of optimistic as most don’t have R30 boxes. So for the sake of argument lets assume that his system cycles twice as much, 8 times a day.

Again, some simple math (0.0438*8=0.3504), 1/3A is used for start up alone.

Rich also said a thin plate system starts 100~150 times a day. Again, I think that is kind of high, so lets go with his low number, 100 cycles a day.

Math once again (0.0483*100=4.83) tells us that this system will consume almost 5A on start up in a 24 hour period.

So assuming everything else is equal, holdover plates use less power in 24 hours on start up alone.
Now I have not factored in run time/s which will up the total daily current draw. By how much I don’t know. But I’m willing to guess that the total daily run time on a holdover system is going to be less that a thin plate system.


Please feel free to correct any thing that I have just wrote.

[a64pilot]

It’s not that simple, add in that there is a significant time until the refrigerant is compressed, moved around and the plate cooled down, condenser heated etc.
So it’s not like turning on a light, The compressor has a significant run time before it really starts cooling and until then your wasting energy. Turn on your AC. You don’t get instant cold air for example.
However the excessive number of cycles is likely due to two things, first an empty box so very little heat is required to raise the temp, if it were full of food then the times would be longer.
And secondly maybe a real tight spread between compressor on and off temps. Now to be fair and honest it’s likely that a cold plate can hold temps much more exactly without excessive cycling so to make the test fair both thermostats may be the same?
However if you want to reduce the amount of cycling, you need to set several degrees between on and off temps, like maybe a 5 degree spread, then cycling would be reduced significantly.

However then of course people would correctly state that the test was not fair and equal cause the two systems had different thermostat set points.

Many the two systems are different enough that any test may favor one over the other, depending on test parameters and set up?
Sort of like which is better, gas or Diesel? Well first what is the mission cause you will get different answers with different missions.

[a64pilot]

My Engel is a thin plate evaporator, and you can hear this thing run, I have not timed it but think it cycles about three times an hour when set to its coldest temp, much less if used as a fridge.

[john61ct]

Originally Posted by newhaul

yes but if you don't have to live without it why would you ?

All depends on one's priorities.

I wouldn't exchange my time living rough in the bush with "primitive" people, for lifetimes of opulent comfort.

And neither would my spawn that grew up able to be comfortable anywhere.

The feelings of wonder and gratitude from indoor cooking and heating, flipping on a light switch or drinking from a tap, stays with us all our lives, priceless

And not to be taken for granted, all too easy for our modern very fragile infrastructures to collapse. . .

[SV THIRD DAY]

A Friend of mine, Capt Greybeard from SeaTec Systems used to say:

"Ice is the real sign of Civilization, Everything else is just Show"

[newhaul]

Originally Posted by john61ct

All depends on one's priorities.

I wouldn't exchange my time living rough in the bush with "primitive" people, for lifetimes of opulent comfort.

And neither would my spawn that grew up able to be comfortable anywhere.

The feelings of wonder and gratitude from indoor cooking and heating, flipping on a light switch or drinking from a tap, stays with us all our lives, priceless

And not to be taken for granted, all too easy for our modern very fragile infrastructures to collapse. . .

hence setting the boat/ home up to be largely self sufficient.
I agree living and growing up off grid for a few years has shaped my personality.
I have tried to impart that in my children as best I can

[john61ct]

Originally Posted by a64pilot

Many the two systems are different enough that any test may favor one over the other, depending on test parameters and set up?
Sort of like which is better, gas or Diesel? Well first what is the mission cause you will get different answers with different missions.

Yes making all the system setup exactly the same other than the plate design is not real life.

I'd say 3 identical factors:

2" polyiso insulated, 6 cu ft boxes

full of pint-sized water bottles, 75% full

in 85° ambient, 24 hours to get contents chilled

And otherwise, give the competing makers / vendors a free hand to design and install their components to best suit those parameters.

Then standardize on say five target internal temps:

"just cold enough for beer"

weekend-use fridge

cruising food-safe fridge

cruising normal freezer (spoonable ice cream)

six-months food-safe pork and shellfish


_____
All you then need for results is graphs showing temp variations, and AH per day consumption. And actual retail pricing of the setup, shipped for owner installation.

Of course opening times, warm-contents loading etc could be tested, but IMO would just complicate things without adding much value.

Yes this ignores eutectics' benefitting from shifting cycling times to "free excess" energy production windows. But Pete's claim of such greater efficiency levels would prevail without that factor, making it "even better" icing on the cake for those wanting to take advantage of it.

Note each design tested under all five temps, but multiple design entries could be shown from each entrant, that optimize for one temp over others.

Including lower-cost options, showing the price in lower performance or energy efficiency.

[john61ct]

Originally Posted by SV THIRD DAY

"Ice is the real sign of Civilization, Everything else is just Show"

For me it's shown by how a society treats the sick & disabled, children, elderly and its least fortunate families.

Giving them ice is not required. 8-)

[newhaul]

Originally Posted by john61ct

Yes making all the system setup exactly the same other than the plate design is not real life.

I'd say 3 identical factors:

2" polyiso insulated, 6 cu ft boxes

full of pint-sized water bottles, 75% full

in 85° ambient, 24 hours to get contents chilled

And otherwise, give the competing makers / vendors a free hand to design and install their components to best suit those parameters.

Then standardize on say five target internal temps:

"just cold enough for beer"

weekend-use fridge

cruising food-safe fridge

cruising normal freezer (spoonable ice cream)

six-months food-safe pork and shellfish


_____
All you then need for results is graphs showing temp variations, and AH per day consumption. And actual retail pricing of the setup, shipped for owner installation.

Of course opening times, warm-contents loading etc could be tested, but IMO would just complicate things without adding much value.

Yes this ignores eutectics' benefitting from shifting cycling times to "free excess" energy production windows. But Pete's claim of such greater efficiency levels would prevail without that factor, making it "even better" icing on the cake for those wanting to take advantage of it.

Note each design tested under all five temps, but multiple design entries could be shown from each entrant, that optimize for one temp over others.

Including lower-cost options, showing the price in lower performance or energy efficiency.

just one question on all of your parameters why store 6 month meat or especially shellfish?
As to the meats you will not need to store more than 2 months worth ( twice average passage time for most cruising boats ) secondly you are on the ocean shellfish are best when fresh . If you wish more than a few days on hand at a time canning is best to keep long term. All a freezer needs to do is keep ice cream solid. IE: 0℉ it is also acceptable for up to 3 months meat storage with no loss in flavor or quality.

[newhaul]

Originally Posted by john61ct

For me it's shown by how a society treats the sick & disabled, children, elderly and its least fortunate families.

Giving them ice is not required. 8-)

actually john its more represented by how children treat their dependant parents.

[Pelagic]

Originally Posted by john61ct

For me it's shown by how a society treats the sick & disabled, children, elderly and its least fortunate families.

Giving them ice is not required. 8-)

I've always been a fan of Jonathon Swift's "Modest Proposal". [emoji4]

http://art-bin.com/art/omodest.html

[a64pilot]

Originally Posted by newhaul

just one question on all of your parameters why store 6 month meat or especially shellfish?
As to the meats you will not need to store more than 2 months worth ( twice average passage time for most cruising boats ) secondly you are on the ocean shellfish are best when fresh . If you wish more than a few days on hand at a time canning is best to keep long term. All a freezer needs to do is keep ice cream solid. IE: 0℉ it is also acceptable for up to 3 months meat storage with no loss in flavor or quality.

If it will keep ice cream, then all that other stuff is met also.
Look it up do I think to the fat content ice cream has to be pretty cold, sub zero numbers.

Real silly observation, but if your fridge will keep beer ice cold, and your freezer will keep ice cream hard, your in, you really have met the requirements, even if you don’t drink beer or eat ice cream, they are indicators, you don’t need fancy digital thermometers.