Refrigeration - Evaporator vs. Holding Plate

[newhaul]

john still trying to decide what system. Here is a thread drift question.
How thick is your evaporator plate and what is the required/recommended offset for best operation?

[Typhoon]

Our plates are just over 3/8 of inch thick . And we use 1/2 "standoffs"

Regards John

[john61ct]

Originally Posted by jhulmer

I have concluded that although counter-intuitive water cool is way to much maintenance and air cooled is the way to go.

Yes!

Originally Posted by jhulmer

holding plate vs coil plate. Have we concluded that the holding plate system is the most efficient?

Not when isolating BTU vs AH alone.

But enormously reducing # On cycles per day, and taking advantage of "time shifting" when excess solar or gennie runtime results in "free" energy, eutectic captures and stores that in cold for you.

And the other two big Cool Blue overall system advantages: Thermally Adjusting Expansion Valve and huge condensing units make up the difference, getting you not just great efficiency, but solid reliability and finally excellent support.

Originally Posted by jhulmer

I guess looking for the KISS answer.

Step 1, call Rich Boren, SV THIRD DAY here, at 619-609-3432, or info@technauticsInc.com

Step 2 review quote proposal and write a large check

Step 3 install with LOTS of insulation.

Step 4 enjoy cool boat drinks for decades

simple enough. . .

[newhaul]

Originally Posted by ColdEh Marine

Our plates are just over 3/8 of inch thick . And we use 1/2 "standoffs"

Regards John

Ok thanks for the info. Basically I am looking at loosing an inch on my depth in the fridge. Vs. Whatever thickness of plate that can be effectively used in my space which can be anywhere from 1.5 inches to 4.5 inches depending on the thickness of holding plate that will be recommend.
For many that is minimal concern . More important consideration in smaller freezer/refrigerator systems.

[Typhoon]

Originally Posted by john61ct

Yes!

Not when isolating BTU vs AH alone.

But enormously reducing # On cycles per day, and taking advantage of "time shifting" when excess solar or gennie runtime results in "free" energy, eutectic captures and stores that in cold for you.

And the other two big Cool Blue overall system advantages: Thermally Adjusting Expansion Valve and huge condensing units make up the difference, getting you not just great efficiency, but solid reliability and finally excellent support.


Step 1, call Rich Boren, SV THIRD DAY here, at 619-609-3432, or info@technauticsInc.com

Step 2 review quote proposal and write a large check

Step 3 install with LOTS of insulation.

Step 4 enjoy cool boat drinks for decades

simple enough. . .

Our systems are also TXV based . No , fixed orifice, capillary tube or CPV , (constant pressure valve)

Regards John.

[john61ct]

good to know, what compressors?

eutectic plates or evaporators or either?

[jhulmer]

Originally Posted by john61ct

Yes!

Not when isolating BTU vs AH alone.

But enormously reducing # On cycles per day, and taking advantage of "time shifting" when excess solar or gennie runtime results in "free" energy, eutectic captures and stores that in cold for you.

And the other two big Cool Blue overall system advantages: Thermally Adjusting Expansion Valve and huge condensing units make up the difference, getting you not just great efficiency, but solid reliability and finally excellent support.


Step 1, call Rich Boren, SV THIRD DAY here, at 619-609-3432, or info@technauticsInc.com

Step 2 review quote proposal and write a large check

Step 3 install with LOTS of insulation.

Step 4 enjoy cool boat drinks for decades

simple enough. . .

Yes simple enough, if money and box space was no object.

The price is double the cost of the off-the-shelf units and the OP is looking for an affordable option to this system. As am I.

I just received Richard Kollmann's book in the mail so I plan to spend some time educating myself.
I purchased a water cooled system a month or so ago with plans to install soon. This thread has thrown a wacky wrench into those plans.

However, I would rather do it right the first time even at additional cost.

[john61ct]

Off the shelf units have way less space and woeful insulation. Really it's the **box** that's going to make the biggest difference in performance and efficiency.

To me paying the premium is for design help, after-sales service and trouble-free reliability.

Is saving a few hundred worth sacrificing those? Not to me.

[kenbo]

Richard,

As usual, your replies are extraordinarily informative. I do have a few questions. Why do you say that you should target the compressors speed so that it runs at less than a 50% duty cycle. I would think that 70-80% would yield a higher SCOP and still provide a bit of extra capacity. Also, you recommend changing the resistance between the thermostat and compressor to regulate the speed but that works best in a static environment. Why not install an AEO control module on the BD35/50 and be done with it. 50% duty cycle is then pretty much guaranteed in both static and dynamic environments.

Lastly, are there any manufacturers of evaporator plates that use thermal expansion valves rather than cap tubes? My feeling/limited experience is that expansion valved systems have a much higher SCOP.

Again, thanks for all you contributions.

Ken

[Typhoon]

Originally Posted by john61ct

Rich stated in past threads he reckoned the efficiency would be close to equivalent if the evaporator unit incorporated the TXV, much larger condenser and oversized drier/receiver.

The advantage then would be just a few starts per day vs 150+: startup current, plus lower wear and tear, neither being that significant.

The holding plate being more robust is another advantage, if you've ever poked a hole in the thin aluminum scraping ice.

Originally Posted by john61ct

Off the shelf units have way less space and woeful insulation. Really it's the **box** that's going to make the biggest difference in performance and efficiency.

To me paying the premium is for design help, after-sales service and trouble-free reliability.

Is saving a few hundred worth sacrificing those? Not to me.

All our systems are Danfoss based. We also only use Parker produsts for fittings and the receiver dryer.

On going support is our specialty. Helping our clients with any questions regarding box design and installation.

Have a look at our website and feel free to contact us at anytime time .

Regards John

[jhulmer]

valid points all, but given the OPs quest:

Originally Posted by RobMinton
So I'm looking for the most efficient icebox conversion kit for the most reasonable cost.


Why would not a system like this work for his 9 cuft refig box?

Isotherm 2017 Compact Classic Air Cooled Refrigeration Component System

[a64pilot]

Work is a interesting word, yes it would work, but in my opinion unless it's exceptionally well insulated it may not be enough cooling.
Now if it's just meant to be a fridge, then yes that is probably acceptable, but does he want a half and half spillover fridge / freezer?

[kenbo]

To the OP's original question. I think the most refrigeration for the buck is this system from Nova Kool. Nova Kool LT201-RT6 Ice Box Conversion Kit

Ask Sure Marine Service to give you the LT211 option which is the larger BD50 compressor. The RT6 folded evaporator is rated by Nova Kool for up to a 12 ft3 refer box with 4" of insulation.

You may want to consider swapping out the standard control module with a Danfoss AEO control module. This eliminates the manual installation of inline resistors to match the speed of the compressor to the environmental heat load of the evaporator. The AEO will do this on a dynamic basis and assures you of at least a 50% duty cycle. If you stay with the standard control module, 2500 rpm would be a good starting point for installation.

Ken

[SV THIRD DAY]

Originally Posted by jhulmer

I purchased a water cooled system a month or so ago with plans to install soon.

However, I would rather do it right the first time even at additional cost.

Then run from water cooling...why add the maintenance when it's not needed even in the tropics?

There is no such system out there today as efficient as one using a TXV (Thermally Adjusting Expansion Valve) vs a Critical Orifice. We have about beat the topic to death on this and MANY other CF forums. Now systems with TXVs cost more, because they cost more to build. Just the TXV valve alone is more expensive than a thin rolled Aluminum evaporator stamped out by the cargo container in China. So if cost is your decision point, buy an evaporations system, if you want the most efficient design from a daily power usage standpoint you get one with a TXV. That's just the science of the situation. We sell between 20-30 CoolBlue systems a month and YES we are not the cheapest...that's not our design goal. Energy efficiency is, and that just costs a bit more money.

It is hype and marketing BS to claim that a BD50 compressor can handle a 12CF Box....ya right...not on our test bench it can't at 90-degs. But that's the game...make crazy promises and then when they don't work you blame the clients "poor insulation" and you already have his money! But it's simply a crazy way to run a company and do business to make promises that won't come true out in the real world. Technautics isn't the oldest Marine Refrigeration company on the market (Since 1968) by making BS marketing claims and selling blue sky.

[kenbo]

Originally Posted by SV THIRD DAY

Then run from water cooling...why add the maintenance when it's not needed even in the tropics?

There is no such system out there today as efficient as one using a TXV (Thermally Adjusting Expansion Valve) vs a Critical Orifice. We have about beat the topic to death on this and MANY other CF forums.

It is hype and marketing BS, like the claim that a BD50 compressor can handle a 12CF Box....ya right...not on our test bench it can't at 90-degs. But that's the game...make crazy promises and then when they don't work you blame the clients "poor insulation" and you already have his money! But it's simply a crazy way to run a company and do business to make promises that won't come true out in the real world. Technautics isn't the oldest Marine Refrigeration company on the market (Since 1968) by making BS marketing claims and selling blue sky.

Rich,

I know you have lots of data to back up your statements and I agree 12ft3 would be over my limit for a BD50. But on my production boat with a 9ft3 refer, folded evaporator and BD50 running at 3000prm I have no trouble at all making ice and keeping the box at 38°-40°F. I do however use 50-55 Ah/day. Would a 12ft3 box be a bridge too far? Maybe, but maybe not if it was well built and insulated.

I do agree that a TXV system is ideal and I wish some refrigeration entrepreneur would build a system using readily aluminum evaporators and add a small TXV with an appropriately sized condenser and accumulator.