Improving one refrigeration compressor's performance

[RaymondR]

Use it for saving your expensive batteries.

Eutectic solutions can be frozen to form a heat sink and melted to absorb heat zillions of times without deleterious effect whatsoever whereas every type of battery made has a finite charge/discharge cycle lifetime and if one does the fabrication oneself a eutectic tank is cheaper than buying an equivalent plate evaporator.

It's actually a no brainer however it is probably going to take a little time and a lot of words to get everyone on the same page.

[Richard Kollmann]

Originally Posted by RaymondR

Use it for saving your expensive batteries.

Eutectic solutions can be frozen to form a heat sink and melted to absorb heat zillions of times without deleterious effect whatsoever whereas every type of battery made has a finite charge/discharge cycle lifetime and if one does the fabrication oneself a eutectic tank is cheaper than buying an equivalent plate evaporator.

It's actually a no brainer however it is probably going to take a little time and a lot of words to get everyone on the same page.

Cheap eutectic plate's interior evaporator design are not equally efficiency to most properly designed standard evaporator K value performance. This lack of absorbing box area heat is over come as long as there is excessive surplus energy from an extra large compressor.

Energy to operate eutectic plates coming from a 1/6 HP or smaller 12 volt compressor results in compressor running time equal to that of a standard evaporator. The only way to justify eutectic Cheap or a well engineered plates is with alternative source of battery charging electrical current.

[AndyEss]

Originally Posted by AKA-None

Simple if you have power generation that is going unused then use it for something
Make water
Make ice
Make something

Yep.

Eutectic materials can also be used to store heat - e.g. like for showers and dishwashing.

Just received several components for a benchtest of my idea to replace my leaking shore power electric/engine waste heat hot water heater. It took up a lot of space too.

Hopefully I will post some results by the end of the summer.

[RaymondR]

Originally Posted by Richard Kollmann

Cheap eutectic plate's interior evaporator design are not equally efficiency to most properly designed standard evaporator K value performance. This lack of absorbing box area heat is over come as long as there is excessive surplus energy from an extra large compressor.

Energy to operate eutectic plates coming from a 1/6 HP or smaller 12 volt compressor results in compressor running time equal to that of a standard evaporator. The only way to justify eutectic Cheap or a well engineered plates is with alternative source of battery charging electrical current.

Richard, as much as I admire your depth of knowledge regarding boat refrigeration matters and deeply appreciate your unstinting willingness to assist with good advice I am going to have to differ with you on the subject of relative operating efficiencies between constant cycling, evaporator plate and energy storage, eutectic refrigeration systems.

Ozylou's company went to the trouble of setting up a test bed and running trials which from an energy usage viewpoint pretty well settled the question of efficiencies. From memory the overall amp/hour usage of the eutectic tank system was in excess of 40% less over a 24 hour day cycle than the constant cycling system which difference was attributed to the vastly reduced compressor start up and reestablishment of stable operating conditions experienced by the eutectic system.

In any trials of a complex system the experimenter attempts to stabilize as many of the variables pertaining in order to allow the most definitive conclusions regarding the variable or variables of interest and Ozyfridge appears to have successfully done so in their series of trials. I think that Ozyfridge did a very good job of designing the trials in order to achieve definitive results and it will now take a competing set of trials of superior design to change my mind on the subject. In my opinion they established facts which makes the superiority of the eutectic system from a power utilization viewpoint, even without the time of power utilization factor being considered, very obvious. However energy efficiency is only one of a multitude of factors which impact and influence the design of boat refrigeration systems so there's still plenty to argue about.

The second part of your post is one that I am finding difficult from a design viewpoint, if you attempt to get good close spacing on a single tube evaporator within the tank it results in an excessive number of bends and probable back pressure resulting and if one coils it so as to keep from having tight bends poor spacing results. Any advice on this subject from the experts would be appreciated.

[valhalla360]

Originally Posted by Shanachie

Sigh. These arguments seems very 1990s, when people needed to rely on alternators for electricity.

Add a solar panel to your array if you don't have enough amps flowing into your battery bank. Unless you are using your fridge to air condition your boat, a decent-sized solar array will more than handle the draw on any refrigeration system.

Forget about obscure terminology. Let modern technology solve your problem and go sailing.

Yep, in the day's of heavy lead-acid batteries and huge alternator output limited to an hour or two per day...these systems made sense.

With modern systems powered by solar using lithium batteries and efficient compressor based refrigerators, it's a solution in search of a problem.

Better to go with a common modern model where you can find parts and service as that outweighs any tiny efficiency improvements you might gain.

[valhalla360]

Originally Posted by RaymondR

Watts in relation to heat is a measure of heat flow which includes a time factor ie. Joules per second. Now if we'd have stuck to the good old imperial system of units of measure we would have BTUs, a measure of heat content and BTUs/hour, distinctly separate as a measure of heat flow, and everything would be perfectly clear to us non scientists and dumb old roughnecks.

BTU/hour...isn't that the rate of change in BTU? It's a legitimate measurement (as is amp/hr....the rate of change in amperage)...just not sure what it's useful for.

Sorry couldn't resist. After all the back and forth, to claim a better system and then make the same mistake...

[Richard Kollmann]

RamondR, I respect your opinion on both points. If you are referring to Ozefreeze post where they showed a picture of a eutectic plate and a thin plate evaporator in a box calming it was a fair comparison. If they wanted a fair comparison there would have been only one evaporator in the box at a time. First year engineering student would have realized the unbalance of energy consumed by eutectic plate alone made the test worthless. Not to mention the difference of energy between the two (K Value).

I hope you do agree that these small 12 volt compressor can not supply enough energy for a descent size box without another source of energy other than the engine alternator.

Yes my outdated DIY books did describe spacing of evaporator coil in eutectic plates and I manufactured over 300 using that method. Any quality eutectic plate especially with small 12 volt compressors must absorb heat directly from plate's surface to evaporator coil inside plate. And at the same time evaporator coil is cooling box it will divert heat from eutectic solution changing it to ice. Once solution is frozen compressor can be stopped. Only true eutectic plate ice can equal the desired box temperature as well as a standard type evaporator.

Well RamondR the best we can do is agree to disagree. I have made my case on my facts as I see them. It is true my idea of pleasure boat refrigeration is more for a cruising live aboard with separate temperature zones if I have only one box to work with.

[StuM]

Originally Posted by valhalla360

BTU/hour...isn't that the rate of change in BTU? It's a legitimate measurement (as is amp/hr....the rate of change in amperage)...just not sure what it's useful for.

Sorry couldn't resist. After all the back and forth, to claim a better system and then make the same mistake...

You are correct in that BTU/hr is the rate of change in BTU. But you are the mistaken one, that's a perfectly sensible unit if you understand what a BTU is RaymondR was correct in his use of units.

BTU = British Thermal Unit: The ENERGY required to raise 1lb of water by 1°F (SI equivalent units (Joules or Watt hours) 1Wh = 3.41 BTU

BTU/h (or BTUH): The POWER required to raise 1lb of water by 1°F in one hour. (SI equivalent units: Watts or Joules/sec) 1W = 3.41 BTU/h (BTUH)

(The equivalent to Amp/hr would be BTU/h/h)

[rgleason]

Kolmann You are misrepresenting facts and trying to create trouble again. I do hope the Mods will ban you.

I did not say my OzieFridge was inadequate.. it continues to serve us well after more than 20 years of seasonal use. You know nothing about my boat or the system or how we use it..

Peter and Louie have been very patient with my questions over the years, ..and their answers, which will remain private, although the question/answers would help others who are interested, but because of you.

I will no longer participate in a forum that kolman is in.

[Richard Kollmann]

Originally Posted by rgleason

Kolmann You are misrepresenting facts and trying to create trouble again. I do hope the Mods will ban you.

I did not say my OzieFridge was inadequate.. it continues to serve us well after more than 20 years of seasonal use. You know nothing about my boat or the system or how we use it..

Peter and Louie have been very patient with my questions over the years, ..and their answers, which will remain private, although the question/answers would help others who are interested, but because of you.

I will no longer participate in a forum that kolman is in.

I am confused I made a suggestion that you try lowering the thermostat setting to improve performance. You replied with a nice PM thanking me. If my suggestion did not work you could have reset the thermostat. Did lowering thermostat cause your unit to malfunction?

I open the EDIT and went back and reviewed later posts Sorry you got the brunt of aggravation when you did nothing wrong..

[rgleason]

Dear Richard
Things are not always black or white.

My system works properly.

I am always looking for ways to improve my ref system, whether it be better insulation, better eutectic solutions, or better ways to control and operate the system. I don't always execute the ideas, but I will try yours and try to document it properly, I doubt it will damage anything. However I can't say when I will have time to do it as I have many projects.

Quite honestly, I really appreciate the knowledge and understanding that is brought to these threads. and respectful dialog between experts, there is nothing better! Just as long as everyone accepts that there are many ways to accomplish the same goal, and while some ways are better for certain purposes others might be good for a different situation.

I will read this thread, but try not to comment any further. I hope it has a long life!

Thank-you for reaching out Richard. I hope you understand my shock at finding out that I had a problem ref system. Which you now know is ok.

Please keep in mind that you can meet friends here, and you can know them for years. That is possible if the relationship is good. I hope we can become friends at some point. Let's try to work on that, and have some good technical fruitful discussions too!

[redsky49]

Well, I'm a retired engineer too. BFD! However, this word salad advo speak is simply gobbledygook.

Originally Posted by SemperAvanti41

*Isotherm Smart Energy Control (ISEC) offers the very unique opportunity to dramatically reduce on board power consumption for refrigeration appliances

Originally Posted by SemperAvanti41

• The sophisticated, processor-based Isotherm Smart Energy Control technology achieves significant power consumption savings by continuously scanning a set of key environmental factors to determine, through advanced proprietary algorithms, what is the most relevant compressor speed to maximize the performance/battery drain ratio (COP)

What? I don't even know where to start with this one.

• The device not only makes your fridge intelligent but also allows the storage of a significant amount of cold energy into the loaded food and drinks

You mean other manufacturers don't make the fridge contents cold?

• Isotherm Smart Energy Control reduces the cabinet temperature more than a traditional fridge without freezing the food

Explain that whopper please.

• This is continuously monitored by an air sensor in the cabinet

A thermostat. How novel!

• The cooling energy is stored when a power surplus is available (engine on or connection to grid) and reused first, before the fridge is running on battery

Now here is where a cogent argument could be made for cold plates.

• The result: Up to 35 % savings due to a more efficient use of the compressor and up to 50 % savings with combined effects of stored cooling energy in food and drinks

Show me the numbers. Cutting energy usage in half?

I'm just as interested in more effective and efficient refrigeration as the next guy. Probably even more so, as I've been a full time live-aboard cruiser since 2014. But nonsense claims that fly in the face of reality?


You want some "stored cooling energy in food and drinks"? Sure, add a couple six packs of your favorite beer down in the bottom of the refrigerator. Thermal mass. Flywheel effect. This is not new.


It's near impossible to beat the space efficiency and temperature consistency of a proper evap plate system, one that is well sized, designed and installed. That presupposes a decent level of insulation and tight fitting doors.



And it is difficult to beat the energy usage of such a system, unless you have surplus energy that would otherwise be wasted. That would likely be solar or wind generated. And the cost - the purchase, installation, maintenance and depreciation - of those solar or wind devices must be factored into the equation. There is no free lunch.


And finally, when did this become a cut-throat competitive debate, where if all else fails we attack the other side? I haven't been on this forum for a while. It's sad to see some of the arguments being made here.

[OzeLouie]

Originally Posted by Richard Kollmann

RamondR, I respect your opinion on both points. If you are referring to Ozefreeze post where they showed a picture of a eutectic plate and a thin plate evaporator in a box calming it was a fair comparison. If they wanted a fair comparison there would have been only one evaporator in the box at a time. First year engineering student would have realized the unbalance of energy consumed by eutectic plate alone made the test worthless. Not to mention the difference of energy between the two (K Value). It was a true and fair comparison and you had every opportunity to dispute with reputable argument and data but you did not.

I hope you do agree that these small 12 volt compressor can not supply enough energy for a descent size box without another source of energy other than the engine alternator.
Totally disagree as do the users of the thousands of eutectic systems around the world that our company alone has built... And there is plenty of evidence of that, just Google or click here:
https://www.cruisersforum.com/forums...ws-136455.html

Yes my outdated DIY books did describe spacing of evaporator coil in eutectic plates and I manufactured over 300 using that method. So 300 units you manufactured yet there doesn't appear to be anything confirming this!, despite several requests for you to provide data, pictures, web site material etc, these systems still remain a mystery!!! It would be interesting to see what you built, how you controlled them etc Any quality eutectic plate especially with small 12 volt compressors must absorb heat directly from plate's surface to evaporator coil inside plate. And at the same time evaporator coil is cooling box it will divert heat from eutectic solution changing it to ice. Once solution is frozen compressor can be stopped. Only true eutectic plate ice can equal the desired box temperature as well as a standard type evaporator. Really!

Well RamondR the best we can do is agree to disagree. I have made my case on my facts as I see them. It is true my idea of pleasure boat refrigeration is more for a cruising live aboard with separate temperature zones if I have only one box to work with.

Cheers Louie

[waterman46]

Originally Posted by Richard Kollmann

Cheap eutectic plate's interior evaporator design are not equally efficiency to most properly designed standard evaporator K value performance. This lack of absorbing box area heat is over come as long as there is excessive surplus energy from an extra large compressor.

Energy to operate eutectic plates coming from a 1/6 HP or smaller 12 volt compressor results in compressor running time equal to that of a standard evaporator. The only way to justify eutectic Cheap or a well engineered plates is with alternative source of battery charging electrical current.

Richard, what did you mean by “alternative source”? Your position makes a lot of sense if alternative source is generator or engine.
The way I see it, if total daily energy requirement and run time is about the same for eutectic vs evaporator, and if sufficient solar or wind power is not available very regularly then eutectic makes more sense (except for cost) since the eutectic plate run time can be done in one or two sessions per day using engine or generator and saving stress on batteries.

[Uncle Bob]

Originally Posted by Richard Kollmann

Cheap eutectic plate's interior evaporator design are not equally efficiency to most properly designed standard evaporator K value performance. This lack of absorbing box area heat is over come as long as there is excessive surplus energy from an extra large compressor.

Energy to operate eutectic plates coming from a 1/6 HP or smaller 12 volt compressor results in compressor running time equal to that of a standard evaporator. The only way to justify eutectic Cheap or a well engineered plates is with alternative source of battery charging electrical current.

Richard, you keep making this claim even though those that have one of these systems on their boat repeatedly point out that their experience is contrary to your claims. You appear to choose to ignore their performance reports, why is this so?