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Old 12-02-2008, 10:34   #16
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OK, thanks for the update in technology then. It sounds intersting. Lets hope it will be economic price wise and economic output wise.
Int he past, Stirling engines mostly used two forms of heat. Steam or direct flame to heat air. Thus the ability to lubricate was not higly efficient. The result was that the engine had to have work "maintenance" carried out on it from as low as 500hrs for some to a few thousand hrs for others. The difficulty was not so much that it had to be serviced, but the fact that units were often hermeticaly sealed and service by just anyone was not possible. So the engine had to be returned to the manufacturer. It was not bearings that were the issue, it was the piston/cylinder wall that was the problem.
If these new coolers have found away to lubricate those two contact surfaces, then I guess there is no reason a unit could not run for as many hrs as any other fridge compressor.
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Old 13-02-2008, 00:08   #17
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practical experiment with Stirling cooling

Mr. Gord May,

I think that you might enjoy reading some technical reports on Global Cooling’s Website at http://www.globalcooling.nl/
It looks like that a COP of >1.5 is achieved at a room temperature of 30 degrees C with a interior temp of zero degrees C for their 100 watt model. That would be an EER of 5.1 compared with Engel’s portable units EER of 4.1 at a much easier temperature range.
Why don’t you get them to supply one for testing installed on a boat (yours!) and then tell the forum the results? It would be a real opportunity to make a contribution to energy efficiency for the marine world.
That way you would do all the work and then tell the rest of us the results. Sounds like a win-win situation for us all, retards and rocket scientists alike!
I sure do like this forum, especially when people that have tried it tell us all about it.
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Old 13-02-2008, 01:40   #18
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Cowboy:
Thanks for the link.
My quick review, earlier this week, of the Global Cooling website you linked, did not indicate any applications of the Stirling Cooler larger than about 1 cubic foot (30 litre) capacity.

Apparently, Global Cooling (and others) are working on a 270 litre (9.5 Cu. Ft.) Unit, as described in their research paper:
RECENT ADVANCES IN STIRLING CYCLE REFRIGERATION
by D.M.BERCHOWITZ, D. KIIKKA ,and B.D.MENNINK (Global Cooling & Sunpower)
http://www.globalcooling.com/pdfs/10_recentadvances.pdf

As I previously requested, I’d be very interested to learn of any commercially available Stirling Cycle units, suitable for practical use in cruising boat refrigerators (not small portable coolers).
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Old 13-02-2008, 05:59   #19
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Seems quite chilly on this thread!
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Old 13-02-2008, 23:02   #20
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Personally I like the idea of the little plug in 12v fridges. Even if you have a regular fridge, it's a nice way to add some additional space on. Plus for a long passage it would be nice to have a massive supply of cool sparkling water and beer (the beer for when you're not underway of course, no joke).
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Old 14-02-2008, 00:10   #21
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We need a test of performance


Gord,

At this level of engineering I think that power consumed and COP are better descriptions of cooling performance than the cubic capacity of the cooler. Portable coolers have very poor insulation. What do you think; maybe R=5? With a suitably insulated top loading box a 40 watt cooler with a COP = 2 might cool a few cubic feet. What do you think is reasonable for an R value for such a box, R=20? That would imply three or four cubic feet of capacity.
The next factor is that the performance curves show that the Stirling cooler has better low temperature performance than the Rankin cycle. Indeed, they are useable as cryostats. So the performance advantages for use as a deep freeze may be quite a bit more for the Stirling.
The next point that may affect power consumption is that the Stirling cooling may be modulated over a large range. This may offer another advantage over on/off temperature control that has always been used on ordinary freezers.
I gather that Global Cooling does not manufacture any consumer products. They only make a cooling device that the trade may incorporate into their products. That is why a demonstration to a specific market segment (i.e. the boating industry) may be something that they may be interested in supporting.
I thought that as an administrator for this forum you might have the necessary credentials to get them to supply an evaluation unit to someone who could field test its suitability in a marine deep freeze application.
Is anybody in this forum interested in doing such a field test? It would need to be a well controlled and documented professional test.

Jerry
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Old 14-02-2008, 01:09   #22
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Quote:
Originally Posted by Cowboy Sailer View Post
... I gather that Global Cooling does not manufacture any consumer products. They only make a cooling device that the trade may incorporate into their products. That is why a demonstration to a specific market segment (i.e. the boating industry) may be something that they may be interested in supporting.
I thought that as an administrator for this forum you might have the necessary credentials to get them to supply an evaluation unit to someone who could field test its suitability in a marine deep freeze application.
Is anybody in this forum interested in doing such a field test? It would need to be a well controlled and documented professional test.
Jerry
Jerry:
Are you volunteering?
I am unqualified (by knowledge, time, & motivation) to perform the applied field test you suggest.
I would, however, be more than willing to provide my moral support, and any legitimacy or “weight” my CF Administrative position might carry, to anyone qualified and willing to undertake such testing.

I don’t doubt that the Stirling Cycle cooler can have a relatively high coefficient of performance (COP), nor that it might be adapted to domestic refrigeration applications.
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Old 14-02-2008, 03:18   #23
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Boy the mathamatics of it all are so overwhelming for myself to comprehend.Proof in the pudding seems to be the way to go.What seems stranger is why You "Jerry" carn't see the logic in a newer,lighter whatever boat ya looking for,against an older one that you may have to pay more for in the end by a larger maintenence cost??Surely having a better refer system won't cover the cost of all that."Mathamatics and logic do go hand in hand don't they?",or,"Don't they?"Mudnut.
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Old 14-04-2008, 07:03   #24
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Sorry, late to this thread. We have had one of these for a few months now. We ahave not taken it sailing yet, but will soon - we just put the boat in the water this passt Saturday (YEAH!!!)

We have been thusfar using the Coleman either plugged into AC, or sitting in the car/truck plugged into DC.

I did do a test, and not surprisingly, it could not freeze four gallons of water overnight. Some of it was frozen, I would say about 20%.

Global Cooling lists a similar model using the same engine, but with vacuum panels, that can go as low as -40c.

If I could get another one of these for cheap (we paid $375.00) I would be tempted to rebuild our icebox with VIPs and retrofit the cooler into this. I would need to find out what it uses to tranfer the cold to the plates, it looks liek it MAY use a refrigerant, like CO2.

I took the unit partially apart once, and if I remember, has cooling tubes encircling the sides of the inner box. Our current icebox is small to begin with, so I would think that it could easily handle a 4 foot well insulated box, say 1 in VIPs with another inch of Foam panels on either side. Not gonna happen this year, though. Could be an interesting science project.


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Old 14-04-2008, 08:21   #25
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Very interesting thread here. I have been considering retrofitting our top loading ( stock on our Cal 2-29) icebox with a refer of some description. I have considered either Peltier junction (cheap - simple) of Stirling cycle (cannibalized Coleman Stirling). I have learned a lot here such as the Peltier junction is quite innefficient and would not likely be a good candidate fo such a project on a boat with minimal energy sources (no wind gen or solar panels.)
What Witzgall talks about is just what I had in mind. The insulation around our box is 2" foam on all sides and I could add more to that fairly easily.
I will post results here if I ever actually do this experiment.
Has anyone here already done a project like this? I would love to hear how you did it and what the results were.
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Old 14-04-2008, 09:41   #26
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I have not had a chance to look into this one in depth but it looks interesting:
200 L FPSC cooler.
Product: COOL CARGO 200N
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Old 15-04-2008, 11:43   #27
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Guys (and Gals),

I am posting this in order to lay to rest some of the confusion about Free-Piston Stirling Coolers (FPSC) based equipment (including the Coleman Stirling Power Cooler).
1. Coleman
- The Coleman unit is a re-branded (part# SC-C925) unit manufactured by a company named Twinbird in Japan (using technology licensed from Global Cooling) and their products are distributed outside of Japan and SE Asia by Global Cooling The .nl site has not been updated yet this year so use the .com address
- The Coleman unit uses a small 40W FPSC to pump heat
- Coleman uses a CO2 based thermosiphon (read: Gravity driven heat pipe) to pump heat from the cold chamber
- The 12 deg restriction (a very conservative number by the way) is based on the nature of the thermosiphon and in truth is only appropriate in a very limited number of orientations. In some orientations it can happily operate at >90 deg from horizontal. All of this is really moot anyway because it refers to CONTINUOUS operation at a specific angle. (if your boat is listing at a constant angle of more that 12 deg you've got bigger problems than refrigeration). Under sail you basically just need to make sure that the cooling unit (under the large gray cover) is the system high point. If you regularly cruise at high angle of attacks, there are convective systems, using the same technology, that are completely independent of orientation (SC-JS04 and SC-JS05).
- Availability of the Coleman branded unit is dropping but Twinbird branded units are still freely available from Global Cooling.
- 48W of power consumption is max cold setting in max ambient temperature. In most refrigeration circumstances power draw is 10W to 20W. To freeze it will take 20-48W depending on which freeze setting is used and how hot it is outside. Incidentally, the Coleman unit has no difficulty keeping its cold chamber 0 deg F (Freeze 2) in ambient temperatures well above 100 deg F.
- As alluded to earlier, the Coleman unit is only ONE of the portable refrigerator/freezers available using FPSC technology
2. FPSC's
- Prices range from ~$400 to ~$25,000 (you probably don't need something this expensive but if you want it we've got 'em.
- We'll sell one (FPSC, Portable refrigerator/Freezer), to anyone who agrees, in writing, to abide by US Export law.
- Have (typically) 2 moving internal components and one external moving component
- Do NOT have any internal oil (oil would destroy its performance)
- Some units use active gas bearings to isolate internal moving components but not all (it's a cost thing). Units without active gas bearings rely on fluid dynamic forces created by component geometry and clearances to isolate moving components and advanced dry bearing systems. Twinbird warranties their products for 1 year but I personally have been running one of the Coleman boxes for 3 years continuously in a, with no measurable performance degradation.
- COP's (pumped heat/input power) range from 1.2 to 4 depending on model
- Are able to modulate their capacity almost instantly and to any capacity from 0% to 100%, without sacrificing efficiency. In essence, they only use as much power as is necessary to maintain a set temperature and no more!
- Have extremely long life expectancies (some well over 100,000 hours)
3. Available units
-SC-C925 ~48W max consumption (same as Coleman)
-SC-DF25 ~48W max consumption (same form factor as Coleman w VIP insulation -40 deg capable in single degree increments)
-SC-BV25 or WH25 ~25W (single temp setting (4 deg C) for blood/vaccine/organ transport)
-SC-JS04 ~50W max consumption (self contained refrigeration unit simply add an insulated container like a built in ice box or a typical ice chest, single temperature setting (4 deg C), Convective transfer (fans instead of a thermosiphon so will happily run in any orientation), refrigerate up to 8 cu.ft. with 2 inches of foam insulation)
-SC-JS05 ~80W max consumption (high capacity version of JS04 with 3 temp settings (4,-18,-35 deg C,-35 only achievable up to 4 cu.ft. with 2 inches of foam insulation but come on, that's seriously cold!)
-SC-UL25 ~130W max consumption (same form factor as DF25 but capable of -92 deg C (really, really seriously cold)
-Various stand alone FPSC's ranging from 40W to 150W capacity

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Old 15-04-2008, 13:33   #28
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Jedwards - thank you for this valuable information. I appreciate the price list that you sent me. This information along with the price list has been very helpful. I will have a much better idea of how I want to go about retro fitting our icebox now and the power consumption I can expect.
Thank you again for your time.
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Old 15-04-2008, 13:54   #29
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Sounds like jedwards has the information that we are looking for.

"We'll sell one (FPSC, Portable refrigerator/Freezer), to anyone who agrees, in writing, to abide by US Export law."

Tell us why and how. Who is We?
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Old 15-04-2008, 14:15   #30
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Wink Who "We" are

"We" are Global Cooling.
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