Refrigeration - Evaporator vs. Holding Plate

[Exile]

Originally Posted by Richard Kollmann

Exile, I forgot to ask what size 115 volt SeaFrost compressor do you have they sold both a large 1/2 Horse power and a 1/6 HP compressor. Both were air cooled but the large one sometimes had a water tank attached to it and a water pump.

When I was still in the business I sold a few kits to make this conversion with new condensing units and capillary tube to replace Seafrost low pressure regulator valve. I charged $375 for the kit and serviced it when it was installed by owner.

I don't know the size offhand (came with the boat), but since you say the 1/2hp had a water cooling option that must be it. My understanding is that it cannot be run w/o the water cooling but I'd love to find out I'm wrong on that one. It's located inside the engine compartment so maybe it just shouldn't be run when either the engine or genset has made the compartment hot.

The only problem I have with the water cooling is the inability to leave it running if I'm away from the boat for longer periods. If the strainer gets clogged the circuit breaker will trip but the beer will get warm, the ice cream melt, and the food spoil. Not exactly worthy of a crisis but a bummer nonetheless. My understanding is that the 12v BD systems can be run with air cooling whether or not water cooling is also hooked up.

[Exile]

Originally Posted by OzePete

Cheers OzePete ozefridge@ozemail.com.au

Thanks Pete! Except I did screw up. Seafrost advises adding evaporator plates with a 12v BD system, not the eutectic holding plates I already have (and Rich says will work). But then SF also endorses water cooling as adding efficiency, whereas I don't think Rich believes it matters much (if at all).

Hey . . . great minds do NOT always think alike!

[OzePete]

Originally Posted by Exile

Thanks Pete! Except I did screw up. Seafrost advises adding evaporator plates with a 12v BD system, not the eutectic holding plates I already have (and Rich says will work). But then SF also endorses water cooling as adding efficiency, whereas I don't think Rich believes it matters much (if at all).

Hey . . . great minds do NOT always think alike!

Actually I agree with Rich somewhat. I too am totally against the use of raw water condensing especially as DC power is involved.
Our model AW480 condensing unit is air AND water cooled and can operate from either.
To explain, it starts a cycle as air cooled only with its twin fans at low speed. When the high side refrigerant (condenser) temperature reaches 43C the fans go to high speed and if the pump switch is in the +water position, the micro pump (4watts!)also starts at +43C and circulates water from the FRESH water tank. Once the condenser reduces to 38C the pump goes off and the fans again operate at low speed. This fresh water method eliminates electrolysis and fouling, common with raw water cooled systems.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[OzePete]

Originally Posted by Richard Kollmann

Rich you and John should not get excited over Pete’s thirty day comparison of standard evaporator against a eutectic plate.
Why would they get excited? They are a couple of industry people who actually do know what they are talking about, so I think it would take more than my comparison test to light them up!
The wide difference in watts consumed should tell you it is not a true comparison.
So Richard, here you go again inferring dishonesty, inferring that the report is dishonest and again an inference without any basis in fact. Why don’t you go through the post trial notes with someone who understands refrigeration (Notes are at Eutectic thread in ‘Commercial Posts’) and indicate what is incorrect and support your findings with factual data, not just guess work.
If the difference was 6% to 10% and holding plate system had a TXV flow control this test could be a fare comparison.
Absolute nonsense. Read the notes, both condensing units were identical, have condenser temperature control and therefore perform equally.
Again, in the other threads notes, I have detailed data properly acquired. If you wish to dispute my findings, please present your properly acquired data, but only factual data, not commentary!

Facts that are missing are: Nothing missing at all!
• When systems were operated separately were they started at ambient temperatures?
Richard, view the chart in conjunction with the notes. Each system refrigerated the cabinet for approx 8 days in sequence. We stated with the eutectic system then at the start of day 9 switched over to the cyclic system for it to maintain the cabinet temperature. This process was repeated for 60 days. In both cases the systems were controlled by the same digital thermostat set at =On +4C and off at +2C
• Was it confirmed that Aluminum evaporator’s size and Btu capacity was equal to condensing unit’s Btu output. Overpowering evaporator with excessive flow wastes systems energy efficiency.
Yes the cyclic systems evaporator was sized to suit the application as also indicated via the duty cycle frequency.
• An efficient 12 volt system with proper size standard evaporator will cycle off and on 1.5 times per hour when system is in balance.
As did the cyclic system tested. It averaged 38 starts per 24 hour period.
But your claim quote: “will cycle off and on 1.5 times per hour when system is in balance” is more misinformation. The cycle rate of any system will vary considerably dependant on many factors including cabinet load, ambient temperature, cabinet type and insulation, just to name a few.

• What good is a chart that only show Watts of power consumed and not compressor cycle times. Unnecessary cycling wastes daily energy.
A lot of good because the issue was power consumption and that is measured in watts!
Duty cycle logs were kept during the trials but not added to my report as they are irrelevant and would just confuse the topic. But just for you seeing you raised this, the cyclic system averaged 38.00 cycles per while the eutectic averaged 1.42!

• Anyone seeing an unused holding plate probable full of solution in the same test box as the aluminum evaporator must know this would count for a major test error in watts consumed.
Firstly, the eutectic plate was obviously full!!
And you’re right, the test results do have an error albeit minor and as described in my notes, an error that favours the cyclic system ...
If you study the chart and consumption notes, you will see that the cyclic systems run periods benefited from ‘hold-over’ provided by the previous eutectic run period. This is why the cyclic systems ‘first day’ runs used far less energy than other days.

I have a 24 cu ft Samsung refrigerator with eutectic plates that are not connected to refrigerant lines relying on evaporator in back of box to keep these plates cold.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[Typhoon]

Hi all
We are at the Annapolis spring boat show this weekend .

Hi Richard , I agree that any plate has to be sized for the boxes btu for maximum efficiency .

Thanks for the data Pete . You know me I have plenty of questions .

I will add more after the show.

Regards John

[Richard Kollmann]

Pete, I am sorry that you feel I am questioning your theories but too many times the obscuring or embellishing of the facts of a situation with misleading or irrelevant information will distract attention from the real facts of boat refrigeration. As you already know I have trouble understanding your technical theories and statements on icebox conversion refrigeration unit. I have years of experience in the various engineering disciplines. There are more than 200 boats sailing somewhere in the world with refrigeration systems containing eutectic holding plates I designed and manufactured in my refrigeration shop. I know many of this forum’s readers have heard my position on eutectic evaporator plates before. A eutectic plate can not be justified unless a boat’s energy power grid has surplus alternative power. In the case of 12/24 volt powered compressors rated at less than 800 Btu per hour in warm climates there is little or no surplus electrical energy when relying only on engine alternator alone. To believe that eutectic plates can reduce size of house battery bank is a mistake engine alternators do produce far greater quantities of energy than any small refrigerator compressor ever could. I could go through your responses and pick out all the unusual statements like,
(Also capillary systems don't have the well known TEV issue of gas leaking from frozen fittings.) But I will not because you do have a good product for the right application.

[OzePete]

Originally Posted by ColdEh Marine

Hi all
We are at the Annapolis spring boat show this weekend . All the best for the show John and anyone there contemplating a new refrigeration system would be well advised to have a look at John's products at the Cold Eh display. John also manufactures a quality product.

Hi Richard , I agree that any plate has to be sized for the boxes btu for maximum efficiency . But of coarse.

Thanks for the data Pete . You know me I have plenty of questions . Anytime John, good to communicate with another industry person with similar endevours, besides it gets a bit lonely way down here!

I will add more after the show.

Regards John

Cheers OzePete

[OzePete]

Hi Richard, my response follows in bold...

Originally Posted by Richard Kollmann

Pete, I am sorry that you feel I am questioning your theories Richard, don’t be sorry just respond to questions at my post 109 with some FACTS supporting your innuendos in post 101!

What I quoted in the Eutectic thread at the Commercial Posts section (http://www.cruisersforum.com/forums/...se-200041.html) are FACTS regards the physics of refrigeration, and refrigeration principles, well known to any actual refrigeration engineer. As I suggested in this thread my post 109, you may wish to find a refrigeration engineer and have him / her go through the notes I provided in that Eutectic thread, and explain the fundamentals to you.
but too many times the obscuring or embellishing of the facts of a situation with misleading or irrelevant information will distract attention from the real facts of boat refrigeration. Yes Richard I agree, we don’t want to wrongly quote and support blatantly incorrect information do we? Bad information / advice like quote: ‘an air cooled refrigeration systems high side pressure should not exceed 120PSIG’ or that ‘you can’t measure refrigeration unit supply voltage with a multimeter, etc etc..
It has been the presenting and defending of such bad / wrong information (especially when espoused by a poster assumed to have a degree of knowledge regards the subject!) and understanding the consequences of such, that caused us to do this extensive trial on this power efficiency issue, the first of many to come!.

As you already know I have trouble understanding your technical theories and statements on icebox conversion refrigeration unit.Yes, that is obvious Richard as you don’t seem to comprehend the effects power consumption wise, of the two main factors causing a large difference in consumption, those being differing COP factors and the energy losses due to a huge difference in the number of daily start ups . Again may I suggest you get a refrigeration engineer to go through the notes provided and explain this to you? Also as previously offered, I am always available to discuss our system or the principals involved with ‘eutectic refrigeration’.

I have years of experience in the various engineering disciplines. There are more than 200 boats sailing somewhere in the world with refrigeration systems containing eutectic holding plates I designed and manufactured in my refrigeration shop. Richard, in over 50 years I and my companies have engineered, built and in some cases installed more than 8000 systems, mostly eutectic, so perhaps you may consider that we too may have learnt a thing or two! We are currently building a batch of 50 eutectic systems for a client, the first batch of many. (See details a “Commercial Posts. New eutectic refrigeration model - Cruisers & Sailing Forums)
I know many of this forum’s readers have heard my position on eutectic evaporator plates before. A eutectic plate can not be justified unless a boat’s energy power grid has surplus alternative power.Yes and it’s exactly this type of broad comment that needs qualifying as it is not totally correct. In the case of 12/24 volt powered compressors rated at less than 800 Btu per hour in warm climates there is little or no surplus electrical energy when relying only on engine alternator alone.Yes and again it’s exactly this type of broad comment that needs qualifying as it also is not totally correct. To believe that eutectic plates can reduce size of house battery bank is a mistakeAgain it’s exactly this type of broad comment that needs correcting as it is totally incorrect.
engine alternators do produce far greater quantities of energy than any small refrigerator compressor ever could. Agree there is far more power from these ‘Heath Robinson’ belt drive outfits, but many don’t want to run a large diesel everyday just to keep the fridge cold, it’s crazy

I could go through your responses and pick out all the unusual statements like,Absolutely please do but state facts and data in your response, and while you are at it you might like to respond to my post 109 here where I objected to your innuendos and requested that you support your statements with facts
(Also capillary systems don't have the well known TEV issue of gas leaking from frozen fittings.) Again Richard, I’m sure if you bring this up with any refrigeration mechanic who actually gets his hands dirty (and who doesn’t have a ‘horse in this race’) you will find that TEV especially such a tiny valves are a major source of gas leaking and often on the suction side adding the additional issue of system contamination. Apart from that they are ugly things to have hanging inside the fridge cabinet specially when there is a better alternative.

But I will not because you do have a good product for the right application. Wow, you got that right Richard.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[RonRicco]

Originally Posted by OzePete

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

Actually, Richard would have not "inferred" he would have "implied." You would have "inferred" something from his comment.

I only know that because my wife told me [emoji1]

[Richard Kollmann]

Pete, I am again not trying to analyze or examine your refrigeration system design hardware or its performance. I will point out the many uninformed comments you make like "capillary systems don't have the well known TEV issue of gas leaking from frozen fittings". I believe there are designs where either cap tube or TXV valves are equal in controlling refrigerant super-heat. I stay away from LPR valves for refrigerant flow control. I found that with eutectic plates plate freezing the first day out with the TXV will lowered refrigerator box temperature much quicker.

And as to your comment about my advice to a boater in trouble regarding low refrigerant high pressure on an Isotherm Danfoss compressor unit, I recommended adding refrigerant to reach 120 psi . Cap tube refrigerant flow control on the isotherm system with your advice of 140 psi was and is still wrong for this system.

Any experienced engineer who looks at your comparison chart comparing evaporator plate against eutectic plate, of watts consumed, would surely question the results as I did.
The big difference is probably in a mismatch in evaporator plate Btu capacity to condensing unit capacity. You know the old saying, If, it is way to good to be true it is probably not true… My test comparison done 15 years ago did show a 6% to 8% energy improvement in favor of eutectic plate. Your test of 4577 watts for eutectic plate and 9940 watts consumed for a standard evaporator. Could anyone believe the eutectic plate is 100% more efficient?

[missourisailor]

Now I’m a bit confused!!!

No way do I have the engineering/manufacturing experience as Pete, John and Rich have.
Nor the daily refrigeration experience as Richard K.

But I have been dealing with commercial, industrial and residential equipment for many decades. And confession... only marine equipment for about 12 years.

All of the training and experience that I have had, has always lead me to believe that an expansion valve system is the better method of flow control, over a wider temp range.

An orifice is very good if operated withing the design parameters. Including a narrow band for condenser cooling temp. But for installations where the condenser will see a wide range of cooling air temp, an expansion valve does a better job.

Have I forgotten something basic?

Also, for what it’s worth, in all of the expansion valves systems that I have encountered, the valve was seldom the true problem. And the few that were the issue, most of time, the cause was, owner/tech/mech induced.

[Typhoon]

Originally Posted by missourisailor

Now I’m a bit confused!!!

No way do I have the engineering/manufacturing experience as Pete, John and Rich have.
Nor the daily refrigeration experience as Richard K.

But I have been dealing with commercial, industrial and residential equipment for many decades. And confession... only marine equipment for about 12 years.

All of the training and experience that I have had, has always lead me to believe that an expansion valve system is the better method of flow control, over a wider temp range.

An orifice is very good if operated withing the design parameters. Including a narrow band for condenser cooling temp. But for installations where the condenser will see a wide range of cooling air temp, an expansion valve does a better job.

Have I forgotten something basic?

Also, for what it’s worth, in all of the expansion valves systems that I have encountered, the valve was seldom the true problem. And the few that were the issue, most of time, the cause was, owner/tech/mech induced.

That’s why we use them (TXV)

We have never had a TXV leak or fail I’m sure Rich will agree .

Regards John

[Richard Kollmann]

Originally Posted by missourisailor

Now I’m a bit confused!!!

No way do I have the engineering/manufacturing experience as Pete, John and Rich have.
Nor the daily refrigeration experience as Richard K.

But I have been dealing with commercial, industrial and residential equipment for many decades. And confession... only marine equipment for about 12 years.

All of the training and experience that I have had, has always lead me to believe that an expansion valve system is the better method of flow control, over a wider temp range.

An orifice is very good if operated withing the design parameters. Including a narrow band for condenser cooling temp. But for installations where the condenser will see a wide range of cooling air temp, an expansion valve does a better job.

Have I forgotten something basic?

Also, for what it’s worth, in all of the expansion valves systems that I have encountered, the valve was seldom the true problem. And the few that were the issue, most of time, the cause was, owner/tech/mech induced.

missourisailor
You are not confused, you are correct and Rich and John will agree with us but Pete will always disagree as he believes he can control super heat by condenser cooling.

[OzePete]

Richard, my response following in bold...

Originally Posted by Richard Kollmann

Pete, I am again not trying to analyze or examine your refrigeration system design hardware or its performance.
Richard, I presented the findings of an extensive trial along with a description of the trial process, pictures and qualifiers. You chose to dispute those figures etc., yet when requested several times, you fail to offer any support for your attempt to discredit my work. May I again request that you support your claims with data, alternate trials etc.
I will point out the many uninformed comments you make like "capillary systems don't have the well known TEV issue of gas leaking from frozen fittings".
Please do and again ask a refrigeration mechanic who actually performs service / repair work on various systems.

I believe there are designs where either cap tube or TXV valves are equal in controlling refrigerant super-heat. I stay away from LPR valves for refrigerant flow control.
I totally agree, to say one refrigerant throttling method is the only solution is absolute nonsense.
I found that with eutectic plates plate freezing the first day out with the TXV will lowered refrigerator box temperature much quicker.
We have thousands of capillary fed systems floating around. The key to a successful capillary system is to use a larger ID capillary tube (NOT 0.6 or 0.66mm ID) at the longer engineered length, use only a true filter dryer like an 032 or 052 and not one of those pencil ‘filter dryers’ rubbish things that are NOT proper filters just strainers, and control the condenser to operate within engineered parameters.

And as to your comment about my advice to a boater in trouble regarding low refrigerant
Firstly his problem was not low on refrigerant, he had an air contaminated system as indicated by his very high amperage. And secondly advising anyone to simply add refrigerant to any system is bad advice without first leak testing, leak repairing, filter dryer replacement and proper evacuation.
high pressure on an Isotherm Danfoss compressor unit, I recommended adding refrigerant to reach 120 psi .
Richard, that is NOT what you said or were advocating then and since.
Following are just a couple of your old posts where you were adamant that high side pressure should NOT exceed 120 PSIG.

(This is what I posted last year while assisting a member in the tropics with a contaminated system drawing excessive amps, followed by your posts contradicting my advice)...

OzePete Post 18, QUOTE: These systems operate at approx 5 to 15 PSI on the low side (suction) and about 140 PSI on the high side (discharge) while running,

Richard, your post 21, 03-03-17, QUOTE: Pressures quoted earlier are wrong for your system with 134a refrigerant you will not see low pressure above 10 psi or low pressure much below 3 psi. High pressures above 120 is also incorrect.
Richards Post 27,QUOTE: For thirty five years fan air cooled systems have operated with high side pressures of 105 psi to 120 psi .

Richard, telling boat owners that their system should not exceed a 120 PSI high side pressure is wrong and troublesome at the least, as understanding high / low pressures is the key to correct system diagnosis.
Richard, I am not sure where you are getting your information from or if you are confused but I can assure you that anyone stating that high side pressure should not exceed 120 PSIG simply does NOT understand the basic fundamentals of refrigeration.. Period!
Suggest checking a Pressure / Temperature chart for 134a refrigerant would be a good start!


Cap tube refrigerant flow control on the isotherm system with your advice of 140 psi was and is still wrong for this system.
Richard, again I suggest you challenge where you are getting your information from because that person has no idea of what they are talking about.
I hope this explanation helps you:
On any R134a system the high side refrigerant temperature (and therefore pressure) is always about 8C to 20C hotter² than the ambient air temperature, therefore a condenser operating in the tropics (as the one in question was) in say a 35C+ ambient, is likely to be operating at approx 45C to 55C³ which relates to high side pressure of 152PSIG and up to 200PSIG., not below 120!!
Note: ² compressed high side refrigerant can only dispose of its heat if it is hotter than the medium used to extract such heat, in this case the air.
Note: ³ In all Danfoss and now Secop data sheets the ‘Test Conditions’ quoted are all for a condenser temperature (high side) of 55C which is approx 200 PSIG, not less than 120PSIG as you advocate!!.
So Richard may I again suggest you find a different source of information.


Any experienced engineer who looks at your comparison chart comparing evaporator plate against eutectic plate, of watts consumed, would surely question the results as I did.
Absolutely we were also surprised at the results, and I would welcome credible comment, in fact I had suggested earlier that you find an experienced refrigeration engineer and get him / her to explain the process, its findings and my notes. Please provide any area of the reported trial that the experienced engineer disputes but only with credible data and engineering reference.

The big difference is probably in a mismatch in evaporator plate Btu capacity to condensing unit capacity. You know the old saying, If, it is way to good to be true it is probably not true… My test comparison done 15 years ago did show a 6% to 8% energy improvement in favor of eutectic plate. Your test of 4577 watts for eutectic plate and 9940 watts consumed for a standard evaporator. Could anyone believe the eutectic plate is 100% more efficient?
Yes, in this trial the eutectic system used approx 50% less power than the cyclic system. Please read the report notes again where the process was detailed and where it was stated that different results were to be expected in different situations / applications. You will also note that I openly invited anyone to inspect the equipment and process. That offer is still available but please if you wish to dispute what is stated then at least have the courtesy of responding with credible data and engineering facts, not just something someone with little actual refrigeration understanding has told you.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[OzePete]

Originally Posted by Richard Kollmann

missourisailor
You are not confused, you are correct and Rich and John will agree with us but Pete will always disagree as he believes he can control super heat by condenser cooling.

More misleading information or perhaps misunderstood. We do control super heat by having our systems thermostatically maintain condenser temperatures within engineered parameters avoiding under or over condensing. If you don't understand this and its benefits Richard, I would be happy to explain further for you.

Cheers OzePete