Refrigerator Box insulation rebuild, Isotherm 2351

[Scubaseas]

Originally Posted by akopac

The davits are held in place horizontally by friction, but have a preventer line under way to keep them from swinging too far aft underway in case of a rogue wave or something. Like I said I don’t extend them underway except in mild conditions. That said panels are cheap (maybe hard to source some places if one broke). I made them bolt-on so the whole davit assembly could be removed for maintenance, or if I sold the boat and wanted to transfer them to another one. I made my own panel mounts from delrin rather than buy them and used some bolts myself. Even if somebody had a wrench it would probably be metric out of the states and at least they are not plastic wing nuts like the store bought ones. Durable and more or less theft inconvenient.
The friction cord angle adjustment has worked flawless for years and can be adjust far enough to face the panels upside down and forward. Be careful what kind of plastics you use as I have gotten some in MX called nilacera and it didn’t do well in the tropical sun.
Most of the time the boat faces North so all the panels are facing aft, but slightly out and angled about 45 or less. If I’m not lazy I’ll adjust them a couple times a day.
Fair Winds
Attachment 1

Thanks for that. Brilliant solution to a common problem.

[OzeLouie]

Originally Posted by akopac

Hey OzeLouie

Can you plug this into your calculator. I messaged the space quit a bit. A 12x4x9 inch bin evaporator will be going vertical somewhere up top to the right. Probably on the back wall. I was off on the internal area. It’s 23.1875 sq. Ft.
Check my work LoL

Thanks Louie

Hi Akopac, Here is an estimate for your cabinet including normal use / loading and based on the information provided: Your details and outcomes are highlighted yellow. The extra insulation thickness and being water cooled help considerably although like has been said here, I too don't like raw water cooled condensers!!
Note using your existing BD35 system the duty cycle is approx 50% in a tropical environment which is quite acceptable. Daily consumption is also reasonable.

[Richard Kollmann]

Originally Posted by OzeLouie

Hi Akopac, Here is an estimate for your cabinet including normal use / loading and based on the information provided: Your details and outcomes are highlighted yellow. The extra insulation thickness and being water cooled help considerably although like has been said here, I too don't like raw water cooled condensers!!
Note using your existing BD35 system the duty cycle is approx 50% in a tropical environment which is quite acceptable. Daily consumption is also reasonable. Louis also does not mention your strange evaporator three detention size as the evaporator is key to selecting compressor.

Attachment 234100

As far as I am concerned charts like this one do not reflect the final performance result in the real world. I do agree that any use of water cooling a small BD size compressor is a mistake for two reasons: Water cooling alone will not insure proper compressor cooling, 2. There is no way to control high temperature/pressure of liquid refrigerant.

Akopac, I spent more than thirty years working designing boat refrigeration in the tropics. Louie approval of the BD35 compressor in your conceptual design assuming a 50% duty cycle in tropical waters at best is a guess. Overlooking the fact that this is a live aboard boat in the tropics with nearly a 100% increase in Btu capacity over standard day temperature not to mention activity in and out of box could change a refrigerator into a drink cooler.. The variable control module on BD50 compressor will manage energy throughout the cruising year's ambient temperature changes. If you go with Isotherm their ASU provides speed changes based on box temperature changes. Other companies using Danfoss BD compressors have available Danfoss AEO modules that constantly adjust speed for beat system coefficient of performance.

[akopac]

Thanks everybody for your all you generous input. I’ll make the box 5in. And bottom and backside 6in as planned. Total volume will be just under 5.25 cubic foot. I’ll use common sense when installing the equipment so if problems arise I’m not having to gut the box to upgrade it. The bin evaporator install and tubing routing will be easily accessible verses buried. Worst case is down the road I upgrade the compressor maybe the condenser to a BD50. All connections will be out side the box and readily accessible. I’ll report back when I get down to MX the status. Pretty good testing grounds[emoji41]

Fair Winds

Andy

[OzeLouie]

[[B]QUOTE=Richard Kollmann;3359516]As far as I am concerned charts like this one do not reflect the final performance result in the real world.

Really!!! Perhaps you could enlighten the industry on your methodology with supporting charts, data application, factors used etc to support your system recommendations. All refrigeration systems ‘in the real world’ are subject to prior engineering with the most important information sought being ‘heat load and power consumption…beats guesswork, a wet finger in the air or opinion every time!

I do agree that any use of water cooling a small BD size compressor is a mistake for two reasons: Water cooling alone will not insure proper compressor cooling

Yes some water cooled systems have no compressor / MDM fan cooling but properly engineered air /fresh water cooled systems also have similar air over compressor /MDM as the air only systems. Also water cooled systems dispose of condenser heat much more efficiently thus reducing high side pressure/ temperature and therefore compressor temperature, so expect an air/ water cooled system to not only run cooler but more efficiently. Especially important in the tropics.

2. There is no way to control high temperature/pressure of liquid refrigerant.

Oh yes there is.
Agree with the earlier keel cooler method but top of the line air / water cooled systems do have condenser temperature control that maintains condenser temperature / pressure to within optimum parameters automatically. This prevents over or under condensing and again improves efficiency.

and out of box could change a refrigerator into a drink cooler.. The variable control module on BD50 compressor will manage energy throughout the cruising year's ambient temperature changes. If you go with Isotherm their ASU provides speed changes based on box temperature changes. Other companies using Danfoss BD compressors have available Danfoss AEO modules that constantly adjust speed for beat system coefficient of performance.[/QUOTE]

The poster already has equipped he wants to use and given the factors of his project, he will get good results in tropical environments.. See Heat Load calculator pic. and Richard if you need advise on how this estimator functions, please contact

[RaymondR]

How does one "over condense" vapors either condense or not?

[OzeLouie]

Originally Posted by RaymondR

How does one "over condense" vapors either condense or not?

Raymond, firstly it is important to understand that pressure and temperature are related, low pressure low temperature etc.

Compressed heat laden refrigerant gas is usually condensed into high pressure liquid when its heat is mostly removed.

Under condensing: If under condensed the compressed gas fails to condense totally into a liquid, usually because the air expected to accept the condenser heat is too hot for adequate transfer or the condenser area / fan or whatever is blocked/ faulty or inadequate. The industry often refers to this as 'flaking out'!!

Over condensing: This is when the condensed liquid is excessively cooled causing the liquid pressure to be abnormally low, slowing refrigerant flows as the evaporator / suction pressures are also effected. Not a problem in warmer areas but a real problem in colder climates and the reason we have thermostat control of the condenser to within a 5c hysteresis.

[Richard Kollmann]

Really!!! Perhaps you could enlighten the industry on your methodology with supporting charts, data application, factors used etc to support your system recommendations. All refrigeration systems ‘in the real world’ are subject to prior engineering with the most important information sought being ‘heat load and power consumption…beats guesswork, a wet finger in the air or opinion every time!

Louie, Thanks for asking about my methodology or overarching strategy it is based on years of industry experienced successes and failures. Charts are a good sales staff tool but there are too many variables in pleasure boat refrigeration so I believe common sense should rule when custom designing a system. It also helped to have spent 34 years as a Director of engineering and maintenance of HVACR equipment.

RaymondR you ask "How does one "over condense" vapors either condense or not?"
In simple terms the efficiency of any of these small systems using capillary tube refrigerant flow control devices it is the volume of flow that confines liquid phase change to vapor within the evaporator. Unlike thermo expansion devices the cap tube systems contain a precise volume of refrigerant. Changes in condenser cooling mediums temperature whether air or water will expand or contract evaporator superheat efficiency. On these small systems Fan air cooled condensers located inside boat have a more stable refrigerant high pressure than the less friendly Water cooled condensers in controlling high liquid pressure/temperature. Over condensing liquid high pressure will reduce refrigerant flow and efficiency of system.

[OzeLouie]

Originally Posted by Richard Kollmann

Louie, Thanks for asking about my methodology or overarching strategy it is based on years of industry experienced successes and failures. Charts are a good sales staff tool but there are too many variables in pleasure boat refrigeration so I believe common sense should rule when custom designing a system. It also helped to have spent 34 years as a Director of engineering and maintenance of HVACR equipment.

Thanks for revealing your system estimate guesswork strategy. I had hoped you too may have a proper heat load calculator and we could compare, so I guess I will have to stay with the refrigeration industry recognised method based on physics, formula and fact.

RaymondR you ask "How does one "over condense" vapors either condense or not?"
In simple terms the efficiency of any of these small systems using capillary tube refrigerant flow control devices it is the volume of flow that confines liquid phase change to vapor within the evaporator.

That is why condenser temperature control (as on a few of the better marine systems) to within the systems optimum parameters, provides the greatest efficiency. BTW TX valve systems are also effected by over or under condensing but to a lesser degree.

Unlike thermo expansion devices the cap tube systems contain a precise volume of refrigerant. Changes in condenser cooling mediums temperature whether air or water will expand or contract evaporator superheat efficiency.
On these small systems Fan air cooled condensers located inside boat have a more stable refrigerant high pressure than the less friendly Water cooled condensers in controlling high liquid pressure/temperature.

A properly condenser temperature controlled air/ water cooled system will provide far lower compressor discharge pressure, better / more stable temperature maintenance and lower power consumption. For example an air cooled system in a 40C environment will have a compressor high side pressure of approx 185PSIG+ while a water cooled system in 32C water will have a high side pressure of approx 125PSIG. The air cooled system high side pressure will drop by up to 50 to 60 PSI as the day/ night cools while the water cooled system will maintain much the same pressure, so not sure where you get the idea that water cooling is erratic unless you are referring to those uncontrolled raw water thingos!

Over condensing liquid high pressure will reduce refrigerant flow and efficiency of system.

Agree, that is what I posted!!

[Pelagic]

Just curious, does temperature affect the range and height of a pissing contest ? [emoji849]

[Uncle Bob]

Originally Posted by Pelagic

Just curious, does temperature affect the range and height of a pissing contest ? [emoji849]

[Richard Kollmann]

(Louie Quote), Richard Thanks for revealing your system estimate guesswork strategy. I had hoped you too may have a proper heat load calculator and we could compare, so I guess I will have to stay with the refrigeration industry recognised method based on physics, formula and fact.

Louie or Pete If you are really interested in how I calculate sizes of refrigeration equipment and power requirements for pleasure boat refrigeration watch the slide show "What Works and What Doesn't on my web site. This link has had thousands of hits with no negative comments. The end recommendation is a worst case tropical calculation adjustable by ambient temperature corrections reducing amperage and Btus Two percent per degree of cooler ambient temperature. Because of the many types and amounts of insulation I always use two to three inches of polyurethane as a Standard knowing that doubling this insulation will only improve performance by 15%.

Slightly over designing today is easily compensated for later by lowering speed of variable compressors.

[akopac]

Everything is dry fit. I’m making FRP panels now and blocking to hold it all in place while it dries after I lay it up.
What do you laminate your foam sheets with?
Epoxy? With or without filler? Caulk? Spray foam?
What about the sheet end joints?

[Scubaseas]

Originally Posted by akopac

Everything is dry fit. I’m making FRP panels now and blocking to hold it all in place while it dries after I lay it up.
What do you laminate your foam sheets with?
Epoxy? With or without filler? Caulk? Spray foam?
What about the sheet end joints?
Attachment 238500Attachment 238501Attachment 238502

Urethane adhesive like liquid nails for big sheets, foam in a rattle can for seams.

[Bill O]

Originally Posted by Richard Kollmann

If you are really interested in how I calculate sizes of refrigeration equipment and power requirements for pleasure boat refrigeration watch the slide show "What Works and What Doesn't on my web site. This link has had thousands of hits with no negative comments.

Richard,
Just tried look at the slide show on your site and for some reason it didn't open due to an application error. Always interested to learn something new in the land of refrigeration and this looked like a good one!