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+--- Thread: Time to replace defective and potentially dangerous absorption fridge (/showthread.php?tid=9874)
RE: Time to replace defective and potentially dangerous absorption fridge - cmillsap - 07-16-2013 02:08
Generally heat transfer increases with velocity. This is definitely true for the case of natural or forced (with a fan) convection of air on a heat exchanger.
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I believe that's to a point. Beyond that point, you're moving the air too fast to get adequate transfer. I know that is the case with a radiator in a vehicle. Move the water too fast through it and it will overheat. You need at least a restrictor plate in the thermostat housing, in place of the thermostat, to prevent such a condition.
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Now, do two 4" fans move too much air? I don't know, but I would at least be suspect, especially when placed right at the inferior edge of the coils.
jm02. Carry on!
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John,
There is such a condition called Laminar Flow. That is when a liquid or air is allowed to move in a linear fashion with no baffles or restrictions to create turbulence in the flow. High flow velocity in certain situations sometimes contributes to Laminar flow. Laminar flowing liquid or air does a poor job of transferring heat by convection. Baffles are usually placed into the Laminar flow stream to produce turbulence, thereby increasing the rate of heat transfer.
However, I doubt a Laminar flow condition would be possible passing throught the fridge coils.
RE: Time to replace defective and potentially dangerous absorption fridge - davidbrady - 07-16-2013 13:34
That's right Chuck, our absorption cooling unit's piping are loaded up with dimples, creases, and crevices to stir up the flow and discourage laminar flow.
RE: Time to replace defective and potentially dangerous absorption fridge - gondolaguy - 07-16-2013 22:37
(07-16-2013 13:34)davidmbrady Wrote: That's right Chuck, our absorption cooling unit's piping are loaded up with dimples, creases, and crevices to stir up the flow and discourage laminar flow.
http://www.youtube.com/watch?v=oJhxgzm1Ye8
David, This may be over your head, call me if you need some tech advice for interpretation.
Corey
RE: Time to replace defective and potentially dangerous absorption fridge - al perna - 07-17-2013 08:00
is that the fridge your going with Corey ? I like !!! that was awesome , now I understand lol
RE: Time to replace defective and potentially dangerous absorption fridge - gondolaguy - 07-17-2013 08:51
(07-17-2013 08:00)al perna Wrote: is that the fridge your going with Corey ? I like !!! that was awesome , now I understand lol
The one I'm going with is similar, 18 cu ft with french doors. Where are you guys at these days Al?
RE: Time to replace defective and potentially dangerous absorption fridge - davidbrady - 07-17-2013 16:31
(07-16-2013 22:37)gondolaguy Wrote: David, This may be over your head, call me if you need some tech advice for interpretation.
Corey
Hi Corey,
It looks like with Samsung's Digital Inverter Compressor technology, DIC, Samsung has eliminated the duty cycle approach that other compressor refrigerators rely on. This means that my calcs for power usage may need to be modified since I included a duty cycle and a startup inrush current. With DIC both of these are gone but in exchange we have a compressor that runs all the time. So, I think I need to retract my 90W light bulb comparison.
By running the compressor all the time it appears that Samsung is eliminating the inrush current of starting a stopped compressor and by doing so they're better able to regulate internal refrigerator temperatures. I think the literature says that they try to achieve a fluctuation of only 1 deg in internal temps whereas a typical standard compressor refrigerator only achieves a 4 deg (+-) temp fluctuation.
It's good technology. More complex and probably more prone to failure and certainly more expensive to buy and fix, but better in terms of food preservation and maybe even energy savings, but I haven't seen energy numbers for DIC equipped Samsungs.
My Dometic does use a thermostat controlled duty cycle to maintain internal fridge temps, but since there's no compressor there's no inrush current so increased energy usage doesn't apply. I've never put a thermometer in my fridge to check temp fluctuations but I'm going to! Right now we're in sweltering high humidity heat Pennsylvania and the fridge is icy cold and performing as well as ever.
I definitely don't have any fans on mine, but remember the fan draw is at 12V so a 1 amp fan draw is only 1AH and with a 1260AH battery bank it's a negligible draw.
I'm still leaning towards carbon buildup from non-ideal burn mixtures as the cause of the discoloration on surrounding surfaces that some are seeing - until proven otherwise.
I gave mine as thorough an inspection as possible without removing the unit and I wasn't able to identify any discoloration.BTW, does the RF197 use the Digital Inverter Compressor technology. I scanned around a bit and it looks like it doesn't unless I missed it.
RE: Time to replace defective and potentially dangerous absorption fridge - al perna - 07-17-2013 20:21
Corey , we are in Pa for the rest of the week, outside of Phila on the valley Forge side . . it has been hot here , but not as bad as Fla . Like David our fridge is keeping food cold , well it is only a year old . I will go elect if this one were to go dead and cant wait to see your project unfold .
RE: Time to replace defective and potentially dangerous absorption fridge - gondolaguy - 07-20-2013 09:40
New fridge arrived yesterday, what a beauty! Also, what a deal. Through Appliance Connection the price was $1169, no shipping, no tax, shipped to me door. Had I bought at box store $1590 with tax plus I would need to pick up. I am really impressed with the overall quality and love the Platinum finish. Much prefer it over stainless/shiny look.
David, I don't see that this model claims the inverter tech, but not really clear on how that works anyway.
One thing that occurred to me in looking at it is why the dual cooling is used. Most refrigerators send all the cool air through the freezer, then scavenged down for the refrigerator portion. Since cold air sinks, this is relatively easy with the freezer n top. With the French Door design, the freezer is on the bottom, so two cooling compressors are employed. It also means the freezer is a chest type, the most efficient at keeping the cold in the "bin" when opened. All together , great design, great price.
RE: Time to replace defective and potentially dangerous absorption fridge - Arcticdude - 07-20-2013 11:18
Looking forward to your install and after action reports!
RE: Time to replace defective and potentially dangerous absorption fridge - patticake - 07-20-2013 17:01
Corey, one question. How do you determine you have "french" doors? I thought it was built somewhere else? Could it be "American" doors, or "English" doors?