Fridge that uses little, if any, of your battery!

[rgleason]

I would be hard pressed to do heat load calcs in anything but BTUH or btu/hr.

[rgleason]

Originally Posted by Richard Kollmann

I am a believer like you in eutectic energy storing plates when justified. There was a time when hundreds of Water boats">blue water boats around the world had my designed systems and eutectic plates.... I stopped the printer from producing more of my books, My web Forum is shut down and My web site will never be changeable and when the Domain expires it will be gone. I still answer my email and follow threads on this forum....

Dear Mr. Kollmann, this refrigeration history is very interesting, and I hope your books remain in circulation, they are well worthwhile reading on a very practical level. You have my respect and I expect others too. Peace.

[OzeLouie]

Originally Posted by Off Trail

OK, I'll take the poke at Americans and old units. We're an easy target. But.

I never mentioned BTUs, or any other imperial units. I am perfectly comfortable in metric. In the SI system the Joule is the unit of energy, while the watt (representing 1 Joule per second) is a RATE of energy transfer.

Thus to say it take X number of watts to raise some amount of water by a delta T is just incomprehensible. X watts transferring for 10 hours is 10 times the energy of X watts for one hour.

Do you mean watt-hours when you are saying watts? Is this a colloquialism in the refrigeration industry? That I could understand, like folks using amp-hours for electrical energy where the 12 volts are understood from context.

If so you would be better served in making your arguments using standard units.

Can you please confirm? When you say watts you mean watt-hours? A lot of this thrash could go away if this could be clear.

Dan

Yes Dan, you are 100% correct, it is a colloquialism of our industry (here in Oz anyway) It's a lazy way of referring to watt-hours. Similarly how often 'amps' is quoted, meaningless yet understood by the context as you indicate.
I doubt most readers give a rats about labelling, they are here interested in the concept presented of which the labelling error makes no difference, but I will be more careful in future so as to avoid the 'politically correct' police!!! OMG!!! There I go again, quoted 'Oz instead of Australia'

[Off Trail]

Originally Posted by OzeLouie

Yes Dan, you are 100% correct, it is a colloquialism of our industry (here in Oz anyway) It's a lazy way of referring to watt-hours. Similarly how often 'amps' is quoted, meaningless yet understood by the context as you indicate.
I doubt most readers give a rats about labelling, they are here interested in the concept presented of which the labelling error makes no difference, but I will be more careful in future so as to avoid the 'politically correct' police!!! OMG!!! There I go again, quoted 'Oz instead of Australia'

Thanks for the confirmation Louie. This makes your OP a lot more clear.

Cheers- Dan

[rgleason]

OzieLouie
As a professional, I would urge you to use "watt-hours" it will keep all learners on the right path and conform to the standards.


Nevertheless, I really appreciate your posts and have learned a lot. Please say hi to Peter who has been a great help to me.

[StuM]

Originally Posted by OzeLouie

Yes Dan, you are 100% correct, it is a colloquialism of our industry (here in Oz anyway) It's a lazy way of referring to watt-hours. Similarly how often 'amps' is quoted, meaningless yet understood by the context as you indicate.

And there's a bridge for sale in Sydney.

If you believe that, I'd suggest re-reading some of the previous unequivocal statements about metric units such as:
Watts of heat (metric) replaces BTU's
The metric measure of heat ... is in watts (was BTU’s in the Imperial system

Nothing colloquial about those statements. And no mention of the repeated Watt / hour specified in hiis original attachment when in fact the correct unit should have been Watts.

[Uncle Bob]

Louie, I wouldn't get too worked up about the nay Sayers that are here, most if not all have never encountered your product yet feel that they are able to denigrate it based on, of all things the units used to describe its performance, and ,laughingly the suggestion that the holding plate system is so yesteryear and simply doesn't work with a 12 volt system, regardless of the many happy clients that are happy to attest to its actual performance. I guess that you are not alone, Rich Boren also produces a similar holding plate system that receives good reviews, yet Richard continues to insist that the holding plate is incapable of performing with a 12 volt compressor, that it needs to cycle many times a day contrary to reviews posted here.
Keep up the development and I wish you well.
Cheers Bob.

[Dockhead]

Originally Posted by rgleason

Dear Mr. Kollmann, this refrigeration history is very interesting, and I hope your books remain in circulation, they are well worthwhile reading on a very practical level. You have my respect and I expect others too. Peace.

I'd like to second that. I've kept my old reefers working for the last 5-6 years only with the help of Richard's excellent publications, and due to some kind personal advice given on this forum. Thanks, Richard! The beer is cold and the ice is frozen, on board my boat!

[Off Trail]

Originally Posted by StuM

And there's a bridge for sale in Sydney.

If you believe that, I'd suggest re-reading some of the previous unequivocal statements about metric units such as:
Watts of heat (metric) replaces BTU's
The metric measure of heat ... is in watts (was BTU’s in the Imperial system

Nothing colloquial about those statements. And no mention of the repeated Watt / hour specified in hiis original attachment when in fact the correct unit should have been Watts.

Find-and-replace watts with watt-hours in the OP (and in your quoted examples) and the units are understandable.

Not saying the text as written was right. But I think it's more interesting to understand the topic.

Dan

[Dockhead]

Originally Posted by Off Trail

Find-and-replace watts with watt-hours in the OP (and in your quoted examples) and the units are understandable.

Not saying the text as written was right. But I think it's more interesting to understand the topic.

Dan

I would politely suggest that the OP should keep his units straight. Sure, it's a common mistake, and not a death penalty case. But as Stu and others have pointed out, it makes a really bad impression coming from a pro in a technical field who is trying to make convincing technical points. By "really bad impression", I mean an impression that even really basic engineering concepts are not mastered, stuff that anyone with even a semester of engineering training could never mess up. I think it really detracts from otherwise really good points. I do agree with Off Trail that some good technical stuff has come out of this thread despite the kerfuffle about units.

[RaymondR]

Originally Posted by Dockhead

I would politely suggest that the OP should keep his units straight. Sure, it's a common mistake, and not a death penalty case. But as Stu and others have pointed out, it makes a really bad impression coming from a pro in a technical field who is trying to make convincing technical points. By "really bad impression", I mean an impression that even really basic engineering concepts are not mastered, stuff that anyone with even a semester of engineering training could never mess up. I think it really detracts from otherwise really good points. I do agree with Off Trail that some good technical stuff has come out of this thread despite the kerfuffle about units.

I notice the metric performance specs for the Danfoss BD series of refrigeration compressors are quoted in "Watts" with no indicator of a time period. The specs from a US Danfoss site uses "BTU" and again no mention of a time period. One can only assume that they mean "Watts/hr" and BTU/hr". I had similar problems with TXV specs.

I seem to recall that the metric measure of heat was "calories" and the SI system "joule" which is an energy unit which includes heat as energy.

It's no wonder that there's mass confusion and it makes life difficult from the viewpoint of a poor dumb old roughneck.

[fivecapes]

Originally Posted by Dockhead

My father was just such a Luddite -- he used to yell at me for leaving the fridge door open when I was a little kid.

Using WAG and BoE analyses, I arrived at 63kJ per opening of a 130l fridge.

In an attempt to provide support for my numbers I came across this paper by a prof at Trinity University written for a Purdue University conference on refrigeration and a/c in 2006 using slightly more rigorous methods.

He found the open door heat load at about 20kJ per 15sec opening (Table 1, page 6). Not quite 63kJ, but not insignificant.


Perhaps our resident refrigeration experts can weigh in?

[rgleason]

In my business, Architecture & HVAC, the term BTU and MBTU is often used, dropping the /hour and we become reliant on context to determine what is intended. I find this infuriating, quite frankly, when I am trying to figure something out. However I have gotten so used to seeing it now, that I may do it too! (and I don't want to.) We should all try to hew to the proper units.

[RaymondR]

Originally Posted by fivecapes

Using WAG and BoE analyses, I arrived at 63kJ per opening of a 130l fridge.

In an attempt to provide support for my numbers I came across this paper by a prof at Trinity University written for a Purdue University conference on refrigeration and a/c in 2006 using slightly more rigorous methods.

He found the open door heat load at about 20kJ per 15sec opening (Table 1, page 6). Not quite 63kJ, but not insignificant.


Perhaps our resident refrigeration experts can weigh in?

Most boat fridges are top opening.

[Off Trail]

Originally Posted by RaymondR

I notice the metric performance specs for the Danfoss BD series of refrigeration compressors are quoted in "Watts" with no indicator of a time period. The specs from a US Danfoss site uses "BTU" and again no mention of a time period. One can only assume that they mean "Watts/hr" and BTU/hr". I had similar problems with TXV specs.

I seem to recall that the metric measure of heat was "calories" and the SI system "joule" which is an energy unit which includes heat as energy.

It's no wonder that there's mass confusion and it makes life difficult from the viewpoint of a poor dumb old roughneck.

Watts sounds right in this case since it's the rate at which it can transfer energy while running.