Improving one refrigeration compressor's performance

[Uncle Bob]

Originally Posted by wsmurdoch

No!!! I am not trying to give him enough rope to hang himself. It difficult (perhaps impossible) to assign motive, and this is not my motive.

I am a 70 year old retired chemical engineer (BS MS PE) who has a boat with a PG/H2O holding plate freezer/refrigerator refrigeration system chilled by either an engine driven compressor and water cooled condenser or by a 125V air cooled condensing unit who is trying to make sense of the unexpected (by me) results of the testing done by Ozefridge. I want to understand the testing, do some maths, and analyze the results with the hope that I can improve my system and its performance in the Bahamas. irish-eyes-to-the-bahamas.blogspot.com

At age 70 and with a 1988 boat, I doubt that I will be an Ozfridge customer, and I am banking on the good will of the Ozfridge company to provide me with the data that I need.

Bill

Hi, I also have never been an ozefridge customer either however I reached out to Pete when he offered to assist those that were having issues, which I was. I have to say that there was and still is I believe good will aplenty there, that is despite the attempts of some to belittle and denigrate their products and deride their experience, which I understand Pete has over 65 years worth of.
My obvious support for them and their product stems from having experienced their product on a number of local boats and spoken to many owners of said systems, all of whom have very positive feedback. Some of these owners have had their boats for up to 20 years and have indicated that they would purchase again if the need should arise.
Also I have a soft spot for intelligent design well executed.

[waterman46]

Originally Posted by OzeLouie

Bill the Y axis refers to the daily (24hr) consumption in total as compiled by a digital data recorder. This recorder tallies the watts consumed for each day as shown in each days column and also the total consumption for each systems total trial period. It, like most similar quoting in metric, relates to watts as amps can be confusing. Amps relies on supply voltage and that varies making amp-hr consumption rates dubious at best. .

BTW when 'watts' or 'amps' is quoted bare, that is without a time reference, it is usually assumed by most that the related period is one hour. Check out all industry data, fridge / air con ratings, compressor manufacturers etc for confirmation of this.

Good point about using watts and not amps in the experiment reporting. But if watts was actually plotted in this experiment, it would be a series of vertical bars all having nearly exactly the same height. So I believe the plot shows cumulative watt-hours.

I wish I knew as much about refrigeration as the experts on this thread. Learning a lot here, so I'm willing to cut any of them a little slack when it comes to exact terminology of electrical concepts. I find that from the context the units become obvious.

Manufacturers traditionally list the RATE of energy (watts) consumed when the appliance is actively running. These days there are also requirements for them to list the total average energy consumption (watt hours) per year that such appliance will typically require, which requires them to make assumptions about how long the device will actively be running each day.

[RaymondR]

Originally Posted by Richard Kollmann

RaymondR you are assuming that the condensing unit for standard evaporator was operated by a less efficient compressor speed. The state of these new Danfoss variable compressor designed for today do not cycle often as would be indicated by the test in question.
You also did not explain their extraordinary thirty day one hundred percent energy differential. Your summarize of test comparison you agreed test was factual. Please speak to the 100% energy differential there must be a reasonable answer for this.

Hi again Richard,

Yep, that is a very large difference and you might recall that in the Ozypete thread where the data was introduced there was some discussion as to how the increased start/stop causality might be confirmed. Ozypete did PM me and state that they were considering rerunning the trials with independent verification.

Valid and factual are two different things. The output of the experiment was data, ie facts, whether or not the data was valid depends upon the apparatus and methodology used for it's collection.

Since it's the only experiment, where the variables appear to have been controlled, on the comparative efficiencies that we have I tend to the opinion that we are obliges to an analysis of whether or not the apparatus was fit for purpose, and whether the methodology was appropriate for the extraction of valid data upon which we could base a valid analysis.

My recall is a bit iffy these days but I cannot recall having had any reservations about either these salient issues but then the focus at the time was on whether a successful time shift of power consumption in order to minimize battery charge/discharge cycling had been achieved, which I believe the data showed it had and that the difference in overall power consumption was considered an unexpected bonus.

In order to explain the causality of the large discrepancy in electrical power consumption Ozypete proposed the hypothesis that it was caused by the "wasted" electrical power consumption during the period between motor start up and actual commencement of the heat pumping process by the constant cycling, evaporator plate refrigeration circuit used in the experiment.

I tended to accept the possibility of the wasted power hypothesis because on my old boat I had installed an amp meter in the power circuit to the Danfoss compressor on my refrigerator and consequently had observed the high currents often demanded by the compressor during it's start up. If the compressor is cycling say five times an hour and pulling 10-15 amps each time it may accumulate to a significant consumption of watt hours over a 24 hour period.

I'd like to carry out an experiment to quantify the magnitude of the "wasted" power. Unfortunately my 25 year old computerized data collection system, a good quality ten channel A/D converter, has been sabotaged by Bill Gates marketing strategies and since my energy budget doesn't much run to extracurricular activities much these days I'm not too inclined to bother. Maybe someone else could do it.

[OzeLouie]

Originally Posted by wsmurdoch

No!!! I am not trying to give him enough rope to hang himself. It difficult (perhaps impossible) to assign motive, and this is not my motive.

I am a 70 year old retired chemical engineer (BS MS PE) who has a boat with a PG/H2O holding plate freezer/refrigerator refrigeration system chilled by either an engine driven compressor and water cooled condenser or by a 125V air cooled condensing unit who is trying to make sense of the unexpected (by me) results of the testing done by Ozefridge. I want to understand the testing, do some maths, and analyze the results with the hope that I can improve my system and its performance in the Bahamas. irish-eyes-to-the-bahamas.blogspot.com

At age 70 and with a 1988 boat, I doubt that I will be an Ozfridge customer, and I am banking on the good will of the Ozfridge company to provide me with the data that I need.

Bill

Thanks Bill, I can see that your motive is to understand, is encouraging and positive. Be assured that I like my father before me, enjoy assisting anyone with refrigeration issues regardless of product brand.
I am working on piecing together the original thread referred to here and will advise when available. This current thread is full of mis-information as it relies on members memory, so hopefully that will clarify things a bit, at least a good stating place. The original report is at our web site as test data.

It concludes with this:

Negatives:
Initial temperature pull down of a eutectic system is slower than a cyclic system. Expect the first run of a DC powered eutectic system in a hot cabinet to be 3 to 4 hrs.
A eutectic plate takes up more cabinet space than a cyclic plate.
A eutectic system obviously costs more than a cyclic system.

Conclusion:

This trial was conducted correctly and in average uncontrolled conditions so as to replicate a typical environment and as the ambient rose heading into summer, so did the consumption of both systems.

​We always could calculate the power economy that operating a eutectic system with a much higher COP would provide as that is simple indisputable maths, but calculating the loss of efficiency upon compressor start up was not feasible or accurate.
Hence the need for this test, the results of which even surprised us.

We expected the eutectic system to use say 20% to 25% less power than the cyclic system due to the better COP factor, but 50% lower was surprising. In an average of typical scenarios we believe the eutectic system would use at least 30% less power.

The biggest area of cyclic systems inefficiency is obviously the excessive daily start ups and when we consider that the test refrigeration units both had ‘soft start’ motor driver modules and therefore more power frugal, how much worse would the cyclic systems consumption be with the old DOL modules!

Notes:

​Subsequent trials have confirmed these initial findings. Albeit differences in consumption were far less when operating as a freezer and less significant in some other situations such as fully or part loaded cabinet, and in differing environments.

Xxxxxxx manufactured both Cyclic and Eutectic system types at the time of these trials but now recommend eutectic in most cases for obvious reasons.
This trial equipment remains intact and can be checked and tested by anyone wishing to inspect.


Bill, as stated above the 50% reduction claimed in the test reported was exceptional but near typical for +2 to +4C cabinets but certainly not achievable for freezers. The benefit of latent energy stored and phase changing at freezer temperatures is reduced as the COP differences are not so great and daily run cycle start ups are also moderated.

Look forward to assisting whenever possible.

[OzeLouie]

Originally Posted by Uncle Bob

Hi, I also have never been an ozefridge customer either however I reached out to Pete when he offered to assist those that were having issues, which I was. I have to say that there was and still is I believe good will aplenty there, that is despite the attempts of some to belittle and denigrate their products and deride their experience, which I understand Pete has over 65 years worth of.
My obvious support for them and their product stems from having experienced their product on a number of local boats and spoken to many owners of said systems, all of whom have very positive feedback. Some of these owners have had their boats for up to 20 years and have indicated that they would purchase again if the need should arise.
Also I have a soft spot for intelligent design well executed.

You got that right Bob, and Pete's experience is from actually engineering and building systems hands on stuff, yet that causes the resentment of one or two here who for years now have attempted to belittle and denigrate our products and company, despite the almost 100% positive feed back from users. https://www.cruisersforum.com/forums...ws-136455.html

One such false claim was to cast doubt on our ability to provide service world wide.. well by coincidence just this morning, how about this for support:

Email received Friday June 9th from a client in Vero Beach FLORIDA USA!!
Subject: Struck by lightning, help!

We need troubleshooting help. The fridge was on at the time we were struck...

Email my reply: sent 7.04PM same day.

Full instructions including: The compressor should run when power is turned on while the control panel is still disconnected. This is a good sign. If compressor doesn’t run, try replacing module (please see attached “MDM replacement”).

Email received this morning (Saturday 6.00AM)

Louie,
It works! Thank you. The module was the issue and has been replaced.

Why so fast? With covid 19 delays we have been including a free service pack with all international sales so as to avoid delays so this user had the parts on hand that she needed to overcome the lightening strike damage. Now my reckoning is that to have this system up and running again in one day is exceptional and all in Richards back yard, virtually!

[StuM]

Originally Posted by OzeLouie

This trial was conducted correctly and in average uncontrolled conditions so as to replicate a typical environment and as the ambient rose heading into summer, so did the consumption of both systems.

Clearly there are a number of pro eutectic biases in the test and it was certainly not conducted "correctly". The claim in the caption on the graph "in identical situations" is patently false.

To name some obvious issues with the testing process:

The last period for the cyclic system is longest at 11 days of clearly highest ambient temrpatures.
The two previous , shorter tests of 9 day periods were apparently at lower ambient temperatures. Consequently the cyclic total is biased high.

The final cyclic test was clearly conducted in a period of rapidly rising ambient temperatures - hence the escalation in values which is not apparent in any of the other five test periods - further biasing the cyclic figure high.

If the sequence were reversed, i.e. starting with a week of cyclic at lower ambient and ending with eutectic at much higher ambient, the figures for the cyclic would have been lower and the figure for eutectic would have been higher.

The "correct" way to conduct the test would have been to start and end the test with the same system to remove the rising termperature bias to and distribute the numberof of days for each technology evenly throughout the period.

[RaymondR]

Originally Posted by OzeLouie

Thanks Bill, I can see that your motive is to understand, is encouraging and positive. Be assured that I like my father before me, enjoy assisting anyone with refrigeration issues regardless of product brand.
I am working on piecing together the original thread referred to here and will advise when available. This current thread is full of mis-information as it relies on members memory, so hopefully that will clarify things a bit, at least a good stating place. The original report is at our web site as test data.

It concludes with this:

Negatives:
Initial temperature pull down of a eutectic system is slower than a cyclic system. Expect the first run of a DC powered eutectic system in a hot cabinet to be 3 to 4 hrs.
A eutectic plate takes up more cabinet space than a cyclic plate.
A eutectic system obviously costs more than a cyclic system.

Conclusion:

This trial was conducted correctly and in average uncontrolled conditions so as to replicate a typical environment and as the ambient rose heading into summer, so did the consumption of both systems.

​We always could calculate the power economy that operating a eutectic system with a much higher COP would provide as that is simple indisputable maths, but calculating the loss of efficiency upon compressor start up was not feasible or accurate.
Hence the need for this test, the results of which even surprised us.

We expected the eutectic system to use say 20% to 25% less power than the cyclic system due to the better COP factor, but 50% lower was surprising. In an average of typical scenarios we believe the eutectic system would use at least 30% less power.

The biggest area of cyclic systems inefficiency is obviously the excessive daily start ups and when we consider that the test refrigeration units both had ‘soft start’ motor driver modules and therefore more power frugal, how much worse would the cyclic systems consumption be with the old DOL modules!

Notes:

​Subsequent trials have confirmed these initial findings. Albeit differences in consumption were far less when operating as a freezer and less significant in some other situations such as fully or part loaded cabinet, and in differing environments.

Xxxxxxx manufactured both Cyclic and Eutectic system types at the time of these trials but now recommend eutectic in most cases for obvious reasons.
This trial equipment remains intact and can be checked and tested by anyone wishing to inspect.


Bill, as stated above the 50% reduction claimed in the test reported was exceptional but near typical for +2 to +4C cabinets but certainly not achievable for freezers. The benefit of latent energy stored and phase changing at freezer temperatures is reduced as the COP differences are not so great and daily run cycle start ups are also moderated.

Look forward to assisting whenever possible.

That's a very good posting Ozylou it contains good information and only a slight dint of vituperation.

However whilst "calculating the loss of efficiency upon compressor start up was not feasible or accurate" may not be practicable it appears that it would not be difficult to ascertain a reliable quantification experimentally.

We can define when the compressor switches on by monitoring it's current draw. This is valid because the measurement we are attempting is the power consumption and the compressor motor is going to draw current whether it's rotating then or not.

The end state required for the measurement of power consumption is when the moment in time when the evaporator becomes a heat sink ie when it's temperature is lower than the in-enclosure environmental temperature. This should not be too difficult to achieve. A mathematical integration of amps by volts by time should give us a watt hours consumed figure.

Fairly precise quantification is probably the only way to get this bugger of an issue buried with a stake through it's heart.

[StuM]

Originally Posted by OzeLouie

..
One such false claim was to cast doubt on our ability to provide service world wide.. well by coincidence just this morning, how about this for support:.
...

It's this sort of viral marketing in unrelated threads which gets up many people's noses!

[Uncle Bob]

Originally Posted by StuM

It's this sort of viral marketing in unrelated threads which gets up many people's noses!

Stu, to be fair Louie has responded to claims made and repeated previously regarding their ability to support the product and to describe this as viral marketing is at best pedantic, at worst..............

[StuM]

Originally Posted by Uncle Bob

Stu, to be fair Louie has responded to claims made and repeated previously regarding their ability to support the product

Where has that appeared in this thread?

[Uncle Bob]

Originally Posted by StuM

Where has that appeared in this thread?

As you well know, this has been going far longer than this thread!

[Richard Kollmann]

I find it strange that my original post Re: Improving one refrigeration compressor's performance suggesting resetting thermostat, created 145 responses of non related marketing nonsense.The remarkable comments are from boaters that are not experienced with the system in question.
Over the last year these attempts to promote this one product has caused the last three member experts from other companies to with draw from participating in these threads.

[Uncle Bob]

Originally Posted by Richard Kollmann

I find it strange that my original post Re: Improving one refrigeration compressor's performance suggesting resetting thermostat, created 145 responses of non related marketing nonsense.The remarkable comments are from boaters that are not experienced with the system in question.
Over the last year these attempts to promote this one product has caused the last three member experts from other companies to with draw from participating in these threads.

Richard, apparently anyone that has an alternative suggestion/point of view is, in your opinion engaged in marketing nonsense. Considering the thread is currently at 147 posts, am I to assume that yours and only yours is the relevant post, and if so just which one of yours is the magic one?
As to the claim that members from other companies have withdrawn from these threads, perhaps if you managed to withold coments designed to denigrate others then a greater level of community discussion would evolve.

[StuM]

Originally Posted by Uncle Bob

As you well know, this has been going far longer than this thread!

Thank you, you make my point for me. It was totally off topic for this thread.

We all realise that you are a regular apologist for a certain company. But the fact remains that a supplier changing topic and posting links to endorsements of his company and spruiking emails from a customer praising their support in a thread discussing comparative performance of refrigeration technologies is without doubt unrelated (and unwanted) advertising.

[Uncle Bob]

Originally Posted by StuM

Thank you, you make my point for me. It was totally off topic for this thread.

We all realise that you are a regular apologist for a certain company. But the fact remains that a supplier changing topic and posting links to endorsements of his company and spruiking emails from a customer praising their support in a thread discussing comparative performance of refrigeration technologies is without doubt unrelated (and unwanted) advertising.

My appologies oh exhaulted one, you of course have never involved yourself in thread drift, support for another or pedantic nit picking.