Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 20-02-2024, 06:59   #1
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
New installation 3 freezers, Can I get around 4,5 or 6º

Hi

I wanted to make a simple question about coolers. I do not want you to calculate my installation, just a general question, and confirmation about what I choose, to reach temperatures I wish fot my coolers

I am aimed to change the refrigerator units and evaporators, in all my coolers

My set up:
- 1 vertical small cooler, like usual in a hotel room, de 140l, 50mm thick
- 1 well/ark 150l , 50 mm
- 1 well/ark around less than 90l , 120mm thick
Isolator Material polyuretane.

I am in caribbean, and I will be always around ecuator, so exterior temperature is always around 32º

Please, someone who can answer the question , easy way, without not too much effort:

If I use BD35 danfoss, which is going to consume between 45w and 75w ( 130w at most), like this:

https://munaled.com/tienda/isotherm-...50-150-litros/

And keeping into account the thickness , litres, compressor wats..., and the use of evaporators with fans ...

Can I archieve easier these matches:
- 4,5,6ºC inside 50mm thick, 150&140l coolers?
-And, Could I get a few ºC below 0ºC in the 90l, 120mm thickness cooler?
- And if the answer is not both cases, If I join one 150l cooler with the 90l cooler, by means a window or hose (now is like this), but I set in each one evaporator/compressor system, Could I get around 4,5,6º in the 150l one?


About the evaporator with fan, my thinking is that they are faster, but hard to be damaged by missuse of the guest, but this can be another thread

Thanks a l
CombatDiver is offline   Reply With Quote
Old 20-02-2024, 15:32   #2
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Hi. Someone told me that watts used in the domestic freezers are about 150w to 400w. But here in the sail world , the machines are most of them around 45w-100w

Any idea? thanks
CombatDiver is offline   Reply With Quote
Old 20-02-2024, 18:29   #3
Registered User

Join Date: Jan 2023
Posts: 1,490
Re: New installation 3 freezers, Can I get around 4,5 or 6º

I am not completely sure I understand your question, but I'll present our experience.

We have two freezers. One water cooled, one air cooled.

We keep both set about -20C. In the Caribbean. They run about a 50% duty cycle, so about 72 W-hr/day each.

Far, far, FAR more important that the temperature you set or the kind of cooling you have is the level of insulation and sealing you have. A poorly insulated freezer will never perform well. A freezer that leaks ambient air into the box will also not ever work well.
SailingHarmonie is offline   Reply With Quote
Old 20-02-2024, 19:27   #4
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Red face Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by SailingHarmonie View Post
I am not completely sure I understand your question, but I'll present our experience.

We have two freezers. One water cooled, one air cooled.

We keep both set about -20C. In the Caribbean. They run about a 50% duty cycle, so about 72 W-hr/day each.

Far, far, FAR more important that the temperature you set or the kind of cooling you have is the level of insulation and sealing you have. A poorly insulated freezer will never perform well. A freezer that leaks ambient air into the box will also not ever work well.
Hi Harmonie. First of all, thanks for your quote

I wish to know what power do you have in your compressor and what area has your evaporator ( the air cooler )

Let put in this way:
- If my thickness/insulator is 120mm, polyuretane
- Capacity in litres is 90l
- it is a well chamber, with a door in the top, and fits fine, there is no licking
- Compressor will be danfoss BD35F, it can consume around 78W at max
- Air cooled
- the evaporator is a fan unit compact, 275x220x70

And giving your experience and your system, Do you think I could reach temperature below 0ºC?
Do you have a bigger compressor or a bigger evaporator?

Thanks a lot again
CombatDiver is offline   Reply With Quote
Old 20-02-2024, 21:18   #5
Registered User

Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 2,316
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Compressor size/evaporator size are not, (within reason,) the determining factor in what temp you want to hold, what they will do is change the rate at which the temp is decreased in the box, (how fast will they remove heat).
Do the ice block test.
Put a block of ice in each box, (in a dishpan/whatever, so you don't have a water mess,) and leave it in the box for a day to pre-chill the boxes.
Then replace the blocks with new ones of known weight.
After 24 hours remove the blocks and weigh them, (or weigh the melt water).
Each Lb. of ice will absorb 144 BTUs of heat when changing its state from 32F ice to 32F water.
Now you know how many BTUs of heat is entering the box in 24 hours.
Boxes don't keep cold in, they keep heat out.
How many hours per day the compressor runs will be determined by its capacity in BTUs per hour at the temp you want.
With the normal daily opening/closing/adding product, a reefer wants at least about 25>30% or so more capacity than the ice measurement.
A freezer would like to see around 50% more, you're not in it as much but the TD is greater, the greater the temp differential between inside/outside the greater "pressure" you might say, that the heat applies to get into the box.
A real "deep freeze", (hard ice cream,) wants more, and more,,,
As noted above, insulation and good sealing are key, $50 worth of insulation will work better than $500 worth of machinery.
__________________
Beginning to Prepare to Commence
Bowdrie is offline   Reply With Quote
Old 20-02-2024, 21:53   #6
Registered User

Join Date: Mar 2016
Location: San Francisco
Boat: Morgan 382
Posts: 2,916
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by CombatDiver View Post
Hi Harmonie. First of all, thanks for your quote

I wish to know what power do you have in your compressor and what area has your evaporator ( the air cooler )

Let put in this way:
- If my thickness/insulator is 120mm, polyuretane
- Capacity in litres is 90l
- it is a well chamber, with a door in the top, and fits fine, there is no licking
- Compressor will be danfoss BD35F, it can consume around 78W at max
- Air cooled
- the evaporator is a fan unit compact, 275x220x70

And giving your experience and your system, Do you think I could reach temperature below 0ºC?
Do you have a bigger compressor or a bigger evaporator?

Thanks a lot again
120mm is good for a refrigerator. 150mm is good for a freezer. 50mm is crap. Your compressor will never stop running, but if you have unlimited power it might work. A BD35 is enough for a 90l box with good insulation. If you want to calculate how much power it will use, and the duty cycle, you need to do the measurements and calculations.
__________________
-Warren
wholybee is offline   Reply With Quote
Old 21-02-2024, 09:28   #7
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by wholybee View Post
120mm is good for a refrigerator. 150mm is good for a freezer. 50mm is crap. Your compressor will never stop running, but if you have unlimited power it might work. A BD35 is enough for a 90l box with good insulation. If you want to calculate how much power it will use, and the duty cycle, you need to do the measurements and calculations.
Hi Wholybee

Thanks for your comments
I made the calculations with a online calculator, but Im not sure.

With 50mm and 150l, to get 6º, I got Prefrigeration= 76w , 76 / 0.855 => compressor wats 90W.

With 120mm and 90l , to get -10º, as you or someone said, it will be fine to a compressor watts 75W.

The online calculator outputs the refrigeration power. The Compersson wat to do so, I find the formula, Pcomp= Pref/(2 factors)
The 2 factors gives the losses between the electric power / efficiency of the compressor, and effective power to refrigeration we need. In a example are 0.9 x 0.95 = 0.855

If you have some other tool, please tell me
Thanks
CombatDiver is offline   Reply With Quote
Old 21-02-2024, 10:24   #8
Registered User

Join Date: Mar 2016
Location: San Francisco
Boat: Morgan 382
Posts: 2,916
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Here is a document I used in planning my freezer. It has a link to a spreadsheet where you fill in your own values, and it tells you everything you need to know. It will tell you Wh per day used, Ah, per day used, and BTU lost in the box.
https://www.swingcat.co.uk/what/frid...lculations.pdf

I also highly recommend the book "Refrigeration for Pleasureboats" by Nigel Calder. Again, it covers everything.
__________________
-Warren
wholybee is offline   Reply With Quote
Old 21-02-2024, 15:54   #9
Registered User

Join Date: Nov 2018
Location: Ventura,CA
Boat: 1979 Acapulco 40
Posts: 86
Re: New installation 3 freezers, Can I get around 4,5 or 6º

I strongly recommend Dan Foss, BD 50, not the 35 and anything south of the Pacific Northwest requires a minimum of 100 mm of insulation but 150 would be even better. In Central and South America holding plate refrigeration is vastly superior to evaporators, and requires much less energy to maintain.
Glassdog is offline   Reply With Quote
Old 21-02-2024, 17:21   #10
Registered User

Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 2,316
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by Glassdog View Post
I strongly recommend Dan Foss, BD 50, not the 35 and anything south of the Pacific Northwest requires a minimum of 100 mm of insulation but 150 would be even better. In Central and South America holding plate refrigeration is vastly superior to evaporators, and requires much less energy to maintain.
I'll go out-on-a-limb here and say that there are probably few cruisers that are as big of proponents of holding/eutectic plates as I am, (my boat uses eutectic plates).
That said, their operation follows a different path, and the choice between an evaporator plate and a holding plate is not generally predicated on an area of operation, but rather one of the availability and storage of electrical power.
With lots of consistent solar, (and panels to take advantage of it,) along with big batteries, an evaporator unit can function quite nicely.
Where holding plates come into-their-own is when periods of high electrical generation are condensed into smaller time frames, as when an engine or generating set is only used for a short time each day.
Then, with a large excess of power you can run a powerful condensing unit for just a short time to freeze the solution in the holding plates.
Holding plates DO have greater temp swings in the box than evaporator plates, it's just the nature of heat absorption thru the gradually melting eutectic fluid and the surface area involved.
The little 12V units that operate with cap-tubes are not well suited for holding plate operation, no real "metering" of refrigerant takes place.
Best operation with holding plates is a condensing unit using a TXV and receiver that can pump/dump large amounts of refrigerant into the plates until the TXV starts to throttle back.
Another issue is the plates themselves. The commonly seen plates that simply have a few feet of tubing wound around inside them are lacking in surface area of the tubes to quickly absorb the heat from the eutectic solution.
AFAIK, the only eutectic plate with common availability that has a finned tube package for best efficient operation is the one from "Technautics", it has a proprietary tube pack that's finned for quite efficient heat transfer.
They also have, (AFAIK,) the only 12V unit that does use a receiver and TXV to feed the eutectic plate.
Of course, should one be inclined to do so, and possess good skills of soldering/brazing, one can build good eutectic plates with a 1/3>1/2 Hp 120VAC condensing unit operating off of an inverter or shore power.
A BTU is a BTU, and whether by a little 12V unit with an evaporator, or even a 3Hp engine drive running holding plates, you still have to remove the same amount of heat each day.
__________________
Beginning to Prepare to Commence
Bowdrie is offline   Reply With Quote
Old 21-02-2024, 18:01   #11
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by wholybee View Post
Here is a document I used in planning my freezer. It has a link to a spreadsheet where you fill in your own values, and it tells you everything you need to know. It will tell you Wh per day used, Ah, per day used, and BTU lost in the box.
https://www.swingcat.co.uk/what/frid...lculations.pdf

I also highly recommend the book "Refrigeration for Pleasureboats" by Nigel Calder. Again, it covers everything.
Hi Wholybee. thanks a lot for this tool
Besides, Im confused because this tool calculates in BTUs... I guess I have to divide the result by 24(h) and then 3,41 and after that, use the formula divinding by 0,855 to get the compressor power , right?

Anyway thanks a lot for this info!!
CombatDiver is offline   Reply With Quote
Old 21-02-2024, 18:06   #12
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by Glassdog View Post
I strongly recommend Dan Foss, BD 50, not the 35 and anything south of the Pacific Northwest requires a minimum of 100 mm of insulation but 150 would be even better. In Central and South America holding plate refrigeration is vastly superior to evaporators, and requires much less energy to maintain.
Many thanks. But I cant place plates inside the fridge well or whatever is the name. I mean the ones with the door opened in the top, they have very little space to introduce plates ( 240mm x340mm). So thats why I wan to use the evaporator. Can you measure the difference?

ABout the insulator, that's what I have, 120mm for freezer, 50mm for the frigdes...

Thank you for the danfoss BD50. I have a friend here and I could see he has BD50 and with very good results. He has a 250l fridge and holds less than 6º, even 0º in the botton, as there are things iced, and a 100l freezer with -10º or more. Both drived by BD50!!

Thanks a lot
CombatDiver is offline   Reply With Quote
Old 21-02-2024, 18:22   #13
Registered User

Join Date: Aug 2021
Location: PNW
Boat: 35 Ft. cutter, custom
Posts: 2,316
Re: New installation 3 freezers, Can I get around 4,5 or 6º

I would add that the main power savings in a condensing unit, (whether cap-tube or TXV,) of a eutectic system over that of an evaporator system is a factor of the start/stop cycles.
When your condensing unit is starting-up several times an hour the in-rush starting current amount over and above the running current adds up over the days operation.
This is why that given the same number of BTUs of heat removal over 24 hours the evaporator system will show a greater total power usage.
Bottom line, no free lunch.
__________________
Beginning to Prepare to Commence
Bowdrie is offline   Reply With Quote
Old 21-02-2024, 19:21   #14
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by Bowdrie View Post
I'll go out-on-a-limb here and say that there are probably few cruisers that are as big of proponents of holding/eutectic plates as I am, (my boat uses eutectic plates)
That said, their operation follows a different path, and the choice between an evaporator plate and a holding plate is not generally predicated on an area of operation, but rather one of the availability and storage of electrical power.
With lots of consistent solar, (and panels to take advantage of it,) along with big batteries, an evaporator unit can function quite nicely.
Where holding plates come into-their-own is when periods of high electrical generation are condensed into smaller time frames, as when an engine or generating set is only used for a short time each day.
Then, with a large excess of power you can run a powerful condensing unit for just a short time to freeze the solution in the holding plates.
Holding plates DO have greater temp swings in the box than evaporator plates, it's just the nature of heat absorption thru the gradually melting eutectic fluid and the surface area involved.
The little 12V units that operate with cap-tubes are not well suited for holding plate operation, no real "metering" of refrigerant takes place.
Best operation with holding plates is a condensing unit using a TXV and receiver that can pump/dump large amounts of refrigerant into the plates until the TXV starts to throttle back.
Another issue is the plates themselves. The commonly seen plates that simply have a few feet of tubing wound around inside them are lacking in surface area of the tubes to quickly absorb the heat from the eutectic solution.
AFAIK, the only eutectic plate with common availability that has a finned tube package for best efficient operation is the one from "Technautics", it has a proprietary tube pack that's finned for quite efficient heat transfer.
They also have, (AFAIK,) the only 12V unit that does use a receiver and TXV to feed the eutectic plate.
Of course, should one be inclined to do so, and possess good skills of soldering/brazing, one can build good eutectic plates with a 1/3>1/2 Hp 120VAC condensing unit operating off of an inverter or shore power.
A BTU is a BTU, and whether by a little 12V unit with an evaporator, or even a 3Hp engine drive running holding plates, you still have to remove the same amount of heat each day.
Hi Blowdrie

Well I didnt even contemplate this solution, so thanks for share here

Quoting you:
With lots of consistent solar, (and panels to take advantage of it,) along with big batteries, an evaporator unit can function quite nicely.


Thats the case. I have plenty of energy with the sun and LiFePo batteries with a 800Ah capacity.

Im more interested in the evaporator, because I found out a good company, good price, and with this system. Also, as I already said, the evaporator with fan can get inside my chambers better , through the upper door port hole

The point is, maybe I would need more watts , BD50F , as other user said...

thanks
CombatDiver is offline   Reply With Quote
Old 21-02-2024, 19:49   #15
Registered User

Join Date: Feb 2020
Boat: Jeanneau, SO51
Posts: 48
Re: New installation 3 freezers, Can I get around 4,5 or 6º

Quote:
Originally Posted by Glassdog View Post
I strongly recommend Dan Foss, BD 50, not the 35 and anything south of the Pacific Northwest requires a minimum of 100 mm of insulation but 150 would be even better. In Central and South America holding plate refrigeration is vastly superior to evaporators, and requires much less energy to maintain.
Thanks, yes I think the 50 is better to do so...But I need to find something like this with this compresor and autoinstallable..
CombatDiver is offline   Reply With Quote
Reply

Tags
freezer, installation

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engel, Dometic Freezers & Frig Box products macconews Plumbing Systems and Fixtures 16 14-12-2018 09:08
Engle vs ARB 12v fridge/freezers F51 Product or Service Reviews & Evaluations 14 28-04-2015 07:21
For Sale: freezers and refrigerators stainless drawers Bohemian17 Classifieds Archive 1 24-06-2013 19:56
Questions for Folks with Freezers Onboard Jane.Joy Cooking and Provisioning: Food & Drink 28 13-10-2012 05:15
portable electric coolers or freezers jean1146 Plumbing Systems and Fixtures 11 02-07-2008 18:07

Advertise Here


All times are GMT -7. The time now is 05:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.