Freezer Insulation of R-40 per inch or better

[SV THIRD DAY]

Aerogel with an Rvalue of 10.3/in is great....but how much will it cost you to build a Box with it?

The below thread talks about the real life numbers....better be sitting down.

http://www.cruisersforum.com/forums/...ce-171556.html

[Waterrat10]

[Waterrat10]

Seems to me a lot of work for little gain. A good seal R 10-12 seems most prudent.

[SV THIRD DAY]

Originally Posted by Waterrat10

Seems to me a lot of work for little gain. A good seal R 10-12 seems most prudent.

That's a very misleading graph, because how does a cruiser relate to "Heat Flow (MMBTU)"?

So lets put this in terms a little more useful to a Cruiser:
If a R10 Box uses 80Amp hours per day of Power, double that insulation to R20 and you will use 40Amp hours per day, double the insulation again to an R40 and shazam...you are down to about 20-25Amp hours per day. There is a diminishing return true...but I sure wouldn't stop at a R10 and be happy. R20 maybe..sure, it ain't ideal...but that is what most cruisers have and live with due to the realities of space and money.

[Terra Nova]

Originally Posted by CaptnBry

Its 2016 and new advances have been made...

It is great fun to spend thousand$ on improvements for your boat. It is prudent to see that you are getting your money's worth.

[Waterrat10]

Originally Posted by SV THIRD DAY

That's a very misleading graph, because how does a cruiser relate to "Heat Flow (MMBTU)"?

So lets put this in terms a little more useful to a Cruiser:
If a R10 Box uses 80Amp hours per day of Power, double that insulation to R20 and you will use 40Amp hours per day, double the insulation again to an R40 and shazam...you are down to about 20-25Amp hours per day. There is a diminishing return true...but I sure wouldn't stop at a R10 and be happy. R20 maybe..sure, it ain't ideal...but that is what most cruisers have and live with due to the realities of space and money.

I wish it was that linear. It is sort of like increasing the gauge of wire to run you windless in the bow. Ever decreasing rate of returns. Going from 3% voltage loss to 1% Voltage loss then try to get to 0.5% voltage loss. If you are at say R10 you are around 90% efficient and you jump to R20 you are maybe 96% efficient and then jump to R 40 you are at 98% efficient. Diminishing returns on investment. So in Amp hours if you are at say 80 amp hours at R10 then R20 is not going to save you 40 amp hours but but maybe 4 amp hours. Open your ice box once or twice or don' t have a good seal and you can throw that in the head. See what I am saying. I do wish it was linear.

Depending on the temperature difference inside vs outside R10 (90%) would be a little low but best bang for buck where R20 (96%)can save a couple more amp hours but R40 (98%) might only save an additional 0.5 amp hours.

My math above is not exact but a relative illustration of gain to be had.

[Waterrat10]

Seems like for the cost of aerogel or vacuum panels one could update their PWM controller to MPPT or buy a 100 watt solar panel or any number of other ways to make up the difference for prudent spending of boat bucks. Unless you just want the most bad a$$ efficient fridge then go for it.

[SV THIRD DAY]

Originally Posted by Waterrat10

So in Amp hours if you are at say 80 amp hours at R10 then R20 is not going to save you 40 amp hours but but maybe 4 amp hours.

Depending on the temperature difference inside vs outside R10 (90%) would be a little low but best bang for buck where R20 (96%)can save a couple more amp hours but R40 (98%) might only save an additional 0.5 amp hours.

Absolutely incorrect and wrong application of the Data.

I have years worth of real life lab testing data to prove it. And a little time with Google and you would see the problem with your "math".
Personally, I don't care if you are wrong...it doesn't bother me it's your warm beer and energy usage to deal with as you like.

The only reason I have to call ******** is that this is exactly how Chat Room and Dock rumors get started and then some poor Cruiser thinks all he needs is a R10 box because some "expert" on the internet said so and posted a pretty graph. The only problem is the "expert" seemingly is having a problem taking the graph data and applying that to the real life situation of a refrigeration box. Sure there is a diminishing efficiency return on a Per Inch basis of insulation, but a standard refrigeration rule of thumb is that when you double your box R-value you cut the power usage in half and that has been pretty well known and established in the refrigeration industry long before you or I came into the scene. The misleading graph you presented even proves the point if you know how to apply the data presented. So lets look at the data from the graph so others won't make the same mistake.

At R10 the graph shows 10MMBTU rate of heat transfer
At R20 the graph shows 5MMBTU rate of heat transfer
Then at R40 the graph shows 2.5MMBTU rate of heat transfer

Now, since heat transfer rate is directly proportional to system power usage and thereby Amp Hour consumption, it's pretty clear that it will take about twice the daily power to deal with a 10MMBTU heat transfer rate Box with R10 than it would with a Box with a 5MMBTU heat transfer rate with R20. Same in going from R20 to R40.

If you half the heat transfer rate, you half the energy needed to pull said heat out of the box and keep your beer cold and ice cream hard.

[SV THIRD DAY]

Originally Posted by Waterrat10

Seems like for the cost of aerogel or vacuum panels one could update their PWM controller to MPPT or buy a 100 watt solar panel or any number of other ways to make up the difference for prudent spending of boat bucks. Unless you just want the most bad a$$ efficient fridge then go for it.

Ah...that would be true IF there wasn't another variable to deal with and that is the BTU heat removal rate of the refrigeration system.

I'm a fan in the "More Solar" argument because cruisers just never can have enough power, but the "More Solar" argument to deal with your refrigeration system power usage can fall apart if your box insulation and size add up to more daily BTUs of heat entering the Box than your refrigeration system can pull out running 24hrs per day.

My boat for example has 1500W of solar aboard, but none of that excess power would matter to my cold beer and ice cream once I reached the point of more heat entering the box than the refrigeration system could pull out. The equilibrium of heat in and heat out may end up at at 39deg refrigerator, but with my luck it would be at 55 degs.

Add to this the reality that most cruisers have box sizes and insulation R-Values bordering on maxing out their refrigeration systems capacity and bingo....the death spiral...

So here we are with the game of trying to get the best R-value Box they can and the most efficient refrigeration system possible all for ColdBeer at anchor. Some things are just worth the effort.

[Waterrat10]

I am not pretending to be an expert and I am not an expert but I can read a graph. At one time I was a biology and chemistry teach and have worked as a chemist and a biologist. So I am not an expert in insulation but I should be able to read a graph.

If the R value is a linear relationship the line above would be straight. Notice how the graph goes from R2 to R4 you reduce heat flow by 25. If I add an additional R2 I do not reduce heat flow by 25 but instead by about 10. If I add and additional R2 for R6 I reduce heat flow by around 5. Therefore I am getting diminishing returns on my insulation value.

If we use amp hours saved on the y-axis instead of MMBTU it would look the same. So for the first R10 I would save 50 some amp hours but the second R10 for a total of R20 I would only save 5 amp hours. To go from R20 to R40 I would save 2.5 amp hours. Hope that clarifies this a little better.

[SV THIRD DAY]

Sorry...the data is the data...and it comes right from your Graph, you are still off track and misapplying the data. Who goes from an R2 to an R4...your mistake is not putting the data to use in a usable real world way, but being stuck on the trees while missing the Forest. Again...look at the data below right from your graph.

Originally Posted by The Data as cited Earlier and Ignored

So lets look at the data from the graph so others won't make the same mistake.

At R10 the graph shows 10MMBTU rate of heat transfer
At R20 the graph shows 5MMBTU rate of heat transfer
Then at R40 the graph shows 2.5MMBTU rate of heat transfer

Now, since heat transfer rate is directly proportional to system power usage and thereby Amp Hour consumption, it's pretty clear that it will take about twice the daily power to deal with a 10MMBTU heat transfer rate Box with R10 than it would with a Box with a 5MMBTU heat transfer rate with R20. Same in going from R20 to R40.

If you half the heat transfer rate, you half the energy needed to pull said heat out of the box and keep your beer cold and ice cream hard.

[Waterrat10]

I am in full agreement on the importance of cold beer and extreme measures must be had to meet that standard. I say sell the life raft and buy a more efficient fridge. I am just saying that after Going from R2 to R10 you cut your energy use by 80%. Going from R10 to R20 you only gain 9.5%.

[SV THIRD DAY]

Originally Posted by Waterrat10

Going from R10 to R20 you only gain 9.5%.

Incorrect.
Again, the data from the graph you posted shows it.

At R10 the graph shows 10MMBTU rate of heat transfer
At R20 the graph shows 5MMBTU rate of heat transfer

IF you half the heat rate coming into the Box, you cut in half the power needed to pull out said heat and thus cut your power usage by about 50% not 9.5%.

{Note, I do have an edge in understanding this...since it is after all what I do for a living and have test boxes with multiple R-values in the office. I'm happy to explain if you have questions, but I can't just let bogus info be posted without calling it out.}

[CaptnBry]

Originally Posted by missourisailor

Well after doing some research on VIP's, DYI-ing the panels doesn't seem likely. Even with the Autoclave, it doesn't seem that I can get the pressure down far enough to slow down molecular movement.

The info that I gathered are reading pressures in a format that I have never heard (Torr) of but some have stated that even 20~28 inHg is not deep enough.

So much for DYI.

I DO believe the plastic VIPs from Rparts have genuine "Unique and Novel" properties worthy of their Patent. They also insist that the panels are fragile and need to be completely encapsulated in tougher materials (FRP laminations) in all installations.

Perhaps the 'magic' is the core material, not purely Space-Level vacuum ultra low pressures (or lack thereof). If an "Aerogel" type core could be evacuated to minimal Torr, what do your calculations then show?

[Waterrat10]

I see what you are refering to about cutting energy in half. Let me asked this which may clarify this for you. Do you save the same amount of amp hours going from R2- R12 as you would save going from R12 to R22?