Improving one refrigeration compressor's performance

[StuM]

Originally Posted by Uncle Bob

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

I've never used CF to advertise my business.

[RaymondR]

Well there you go, and I thought we were stumbling back into the path of civil reason.

I tend to the opinion that Ozylou, and Ozypete before him, have been more defending than touting and as they are in the refrigeration manufacturing and retailing business they have a right to self defense if criticism of their professional reputations and products are published in the forum.

[Uncle Bob]

Originally Posted by StuM

I've never used CF to advertise my business.

Funny nor have I, however I will stand up for those that have been deliberately targeted with wrong information designed to denigrate them and their product.
I would suggest that we put this to bed and proceed with a rational discussion without rancor or diversion.

[Richard Kollmann]

I agree this thread can be put to bed as it did not offer suggestions on improving an operating refrigeration system's performance which was the original attempt in my post.
Was it a waste of band width, probably not for the large number of boaters and industry people who viewed the entire thread.

[bdgWesternMass]

Originally Posted by RaymondR

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.

I'm at a stage where I need to establish my testing/verification scheme.

If you wanted to outline/schematic or give me guidance I would be happy to use your(or anyone's) knowledge to make I valid measurement system.

I definitely want to make a seemingly normal cooling system with a very smal power footprint.

Thanks,

Ben

[AKA-None]

Originally Posted by StuM

I've never used CF to advertise my business.

Hmmm I guess I never knew you had a business or if I did then what it was. Can’t tell from here

[rgleason]

OzeLouie

Thank you for the informative and balanced assessment of the test. I think it has provided good information for consideration.
I don't believe that treated gallons of water in refrige equaling a eutectic plate vs a eutectic plate are the same, because the transfer of energy is very different.


As a customer from about 20 years ago, located in New England, I can say that shipping was planned for early spring and was not overly expensive. The installation instructions were excellent, the help figuring out where & how to install was great, and the upgrade was a significant change for us. We did not upgrade the batteries and our use patterns do work ok and will improve with some other improvements (solar and a new alternator and later a better battery bank, also needed for our new navigation system and radar). The exchange rates were favorable and replacing a failed water pump years later was painless. Distance proved not to be a significant factor to us, because of their support and my hands on abilities.

That said, I think there are clearly other good systems available. I just happened to like their approach and solutions.


I would like to thank RK for his controlled counterpoints as they are valuable for consideration, and I really appreciate his respect of others points of view. I don't agree with his thoughts about this thread. It has been very helpful.

[StuM]

Originally Posted by AKA-None

Hmmm I guess I never knew you had a business or if I did then what it was. Can’t tell from here

That's because I don't consider CF to be an appropriate venue for advertising, and nether do the forum owners if you read the rules

" Our user base is not a resource to be "mined" by individuals, groups, or businesses, for profit"

"Marine Service Providers may not use any section of the forum to discuss their products or services unless answering a direct question and even in this case may not quote prices or post links, images, videos or contact details in support of that response."

[RaymondR]

Originally Posted by StuM

That's because I don't consider CF to be an appropriate venue for advertising, and nether do the forum owners if you read the rules

" Our user base is not a resource to be "mined" by individuals, groups, or businesses, for profit"

"Marine Service Providers may not use any section of the forum to discuss their products or services unless answering a direct question and even in this case may not quote prices or post links, images, videos or contact details in support of that response."

StuM, I'm reasonably confident that I've read every post in the now numerous threads which constitute the battles in the great evaporator V eutectic-tank war and I'm fairly certain that neither of the primary professional protagonists have used the forum to advertise or introduce products or services other than to establish that they have experience based authoritative opinions on the subject of pleasure vessel refrigeration and that even this was generally bought to the attention of participants by third parties.

[RaymondR]

Originally Posted by bdgWesternMass

I'm at a stage where I need to establish my testing/verification scheme.

If you wanted to outline/schematic or give me guidance I would be happy to use your(or anyone's) knowledge to make I valid measurement system.

I definitely want to make a seemingly normal cooling system with a very smal power footprint.

Thanks,

Ben

Functionally two things occur when a capillary tube flow regulated refrigeration circuit start up.

On The High Side (That part of the circuit between the compressor output and the flow metering device)

Since the capillary tube allows pressure equalization between the condenser and the evaporator liquid refrigerant may be present in both however because it is colder would more likely to be present in the evaporator.

Two things occur on compressor start up and the physical gas laws, particularly P1V1T1 = P2V2T2 come into play .

The compressor pumps refrigerant vapour from it's suction to it's discharge side. Consequently the pressure in the evaporator decreases and the liquid refrigerant starts to absorb heat and boil off.

Concurrently the pressure at the compressor discharge, and consequently in the condenser, increases until it reaches a pressure and temperature where the condenser can "waste" it's heat content and allow it to liquify. The liquid is then metered into the evaporator via the capillary tube.

Unfortunately capillary tubes are not an un-loader type valve which does not allow fluid through until a fixed pressure is achieved and as soon as there is a pressure differential between condenser and evaporator flow will occur and the compressor will have to "chase" this bleed off whilst trying to pressure up the condenser. Similarly in the evaporator boil off of refrigerant may occur before sufficient temperature difference has occurred to create a heat sink.

The system stability operating parameters are achieved when both heat rejection from the condenser heat exchanger and heat acceptance by the evaporator are stable however heat acceptance and refrigeration effect at the evaporator will probably begin to occur prior to stability being achieved.

From a power consumption viewpoint the matter is further complicated by power draw variations caused by the load on the compressor which is generally governed by the compressor speed and, since a hermetic compressor occupies a pressure vessel subjected to the compressors suction pressure, the differential pressure between suction and discharge.

Since, in the instance under discussion, we are interested in the electrical consumption we can start recording consumption data at the point in time when power is switched to the compressor motor. However, since in the subject instance we are only interested in the power consumption between switch on and the commencement of refrigerating effect at the evaporator a sensitive differential temperature control will be required to detect the stop point for power consumption recording.

Op amps and and gates and resisters and electronic things may be required.