Improving one refrigeration compressor's performance

[Richard Kollmann]

The solution to rgleason last post before thread closed would have been to lower thermostat's control over stopping compressor by a minus of ten less degrees F. This adjustment procedure will not store more energy but it will absorb more heat from box. And yes a few more amp/hrs per day but less than running compressor at a greater SCOP.

[StuM]

Sorry, can't resist


That would be "a few more Amp hours per day" or "a few more Ah per day". There is no meaningful unit of amp/hr (Amps per hour) especially "per day".

Or does the "s" stand for seconds? In which case, my mind boggles at the mere thought of trying to make sense of A/hrs per day (Amps / hours * seconds / days)

"Symbols of units of measurement do not have a separate plural form. In other words, no s is added to create the plural. Clearly, not adding the s to the SI unit helps avoid ambiguity."

[Off Trail]

Originally Posted by StuM

Sorry, can't resist


That would be Amp hours (Ah). There is no meaningful unit of amp/hr (Amps per hour) especially "per day".

Or does the "s" stand for seconds? In which case, my mind boggles at the mere thought of trying to make sense of Amps / hours * seconds / days

Of course he means amp-hours per hour. Please let's not ruin another thread.

[OzeLouie]

Originally Posted by Richard Kollmann

The solution to rgleason last post before thread closed would have been to lower thermostat's control over stopping compressor by a minus of ten less degrees F. This adjustment procedure will not store more energy but it will absorb more heat from box. And yes a few more amp/hrs per day but less than running compressor at a greater SCOP.

Richard, I think you may have misunderstood rgleason's request. He wants to increase his systems refrigeration rate of cooling while power is abundant, like while there is excess power from generation while motoring. To do this he needs to make a small alteration:
His condensing unit has a speed selector switch on the front panel. There are two resistors (one for each switch position) Change the higher value resistor to 1700 ohms to cause the compressor to run at maximum speed when 'Hi speed' is selected. He will also need to increase air over the condenser and suggest changing the internally mounted 120-120-25mm fan for a 120-120-37 mounted externally. (Must be rated less than 6 watts) May need to add a little R134a refrigerant also.

He could automate the system so it switches to maximum speed when power is abundant by using a voltage switch to monitor voltage available and once a voltage that indicates batteries are topped up is achieved, have this switch put 300k ohms across the probe circuit and at the same time the 1700 ohms for maximum speed. This will cause your system to switch on prematurely and run harder removing more heat when power is abundant.

[Richard Kollmann]

Amp draw of a compressor have some value when taken from compressor manufacturer's published application engineering charts. If this were a conventional evaporator system where normal operating temperature is in a narrow range measuring amperage there gives a base line with hours run to calculate approximate a reasonable amp/hrs per day. I have used a portable amp/hr meter and cross check with a data logger printed charks. I have done 12 hour recordings in controlled temperature rooms but 24 hour test on a boat is going to be realistic. Say test was done under climate condition in Boston +50 degrees F and there were plans to move boat to move boat to South Florida where weather is 75 plus degrees F warmer then daily amperage would be twice the Boston reading.

Performance amperage on the refrigeration in question is not going to be were accurate because we do not know the heat conducting efficiency design between plate surface area and internal evaporator’s thermo relationship between the two.
Quality eutectic plates have lots of evaporator contact with plate’s surface area.

I realize my responses are conservative I rarely blame insulation or size of compressor or say you purchased the wrong refrigeration. My solutions always begin with Non Destructive testing. If unhappy with the amount of energy your refrigeration needs add electrical power to boats electrical grid or make box smaller by adding insulation to inside of box.

[StuM]

Originally Posted by Off Trail

Of course he means amp-hours per hour. Please let's not ruin another thread.

I make no apologies. As long as posters keep using incorrect units in technical discussions, I will keep correcting that misinformation.
If supposed knowledge area experts don't like it, they should be more professional and use the correct units. As has been pointed out, doing otherwise seriously degrades their credibility.


(And it also leads to confusion among less knowledgable readers when they see this misuse - just look at the threads where an inexperienced member gets totally confused when trying to work out serial/parallel connections and battery bank capacity because they've seen incorrect statements by supposedly knowledgable posters conflatiing Watts, Watt hours, Amps and Amp hours)

[sailorboy1]

Originally Posted by StuM

I make no apologies. As long as posters keep using incorrect units in technical discussions, I will keep correcting that misinformation.
If supposed knowledge area experts don't like it, they should be more professional and use the correct units. As has been pointed out, doing otherwise seriously degrades their credibility.


(And it also leads to confusion among less knowledgable readers when they see this misuse - just look at the threads where an inexperienced member gets totally confused when trying to work out serial/parallel connections and battery bank capacity because they've seen incorrect statements by supposedly knowledgable posters conflatiing Watts, Watt hours, Amps and Amp hours)

Apparently it your issue you use to sideline everything

[Dsanduril]

I’m disappointed Stu You didn’t comment on:

Originally Posted by Off Trail

...amp-hours per hour...

Isn’t Ah/h just A?

[OzeLouie]

Richard started this thread to assist a member regards how to upgrade his existing refrigeration system. Does this thread also have to be side tracked into another pathetic 'look at me, look at me' circus?

[Richard Kollmann]

Louie, Read it again it reads like the system does not perform as is, I only advised him as to how to improve box temperature without modifying or replacing freeze point of solution or building a new insulated box. It takes more than a 23 degree cycling eutectic evaporator plate to freeze even one stake. If the design of plate is efficient my solution my satisfy him.

Boaters are here not to look at you or especally not me they need helpful information.

[StuM]

Originally Posted by OzeLouie

Richard started this thread to assist a member regards how to upgrade his existing refrigeration system. Does this thread also have to be side tracked into another pathetic 'look at me, look at me' circus?

If supposed "professionals" don't want their threads sidetracked, the solution is simple. Use correct units when discussing technical matters.
Not doing so indicates that you are either sadly lacking in basic knowledge in your supposed area of expertise or you are just too lazy to be concerned about accuracy. Neither attribute lends credibility to your posts.

[StuM]

Originally Posted by Dsanduril

I’m disappointed Stu You didn’t comment on:

Isn’t Ah/h just A?

Not necessarily. That is only true with a 100% duty cycle.
With a 50% duty cycle, a 10A load = 5 Ah/h

Consequently confusing Watts and Watt hours (or Amps and Amp hours) can cause major problems, you can either over-spec or under-spec your system which results in drained batteries, blown fuses or just unnecessary costs in the best case.

Which is one of the many reasons I keep harping on about this.

[StuM]

And BTW, Off Trail's "Of course he means amp-hours per hour." is a prime example of the confusion that can arise.

There is a huge difference between "few more amp hours per hour" and Richard's intended "a few more amp hours per day".
One is 24 times more energy required than the other.

[Off Trail]

Originally Posted by StuM

And BTW, Off Trail's "Of course he means amp-hours per hour." is a prime example of the confusion that can arise.

There is a huge difference between "few more amp hours per hour" and Richard's intended "a few more amp hours per day".
One is 24 times more energy required than the other.

Indeed. I saw it as soon as I submitted. Had the previous thread on my brain.

But imo this is just the geek version of grammar policing. Anyway, carry on.

Dan

[StuM]

Originally Posted by Off Trail

Indeed. I saw it as soon as I submitted. Had the previous thread on my brain.

But imo this is just the geek version of grammar policing. Anyway, carry on.

Dan

Bad grammar doesn't have the potential to destroy boats and/or kill people. Incorrect electrical advise does.