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Re: "Cheap" vacuum

 

I am not clear on why you think idling a car is out of the question.
Unlike running my whole farm during a power outage, all you need
to do is run a fridge until you have replaced the energy you lost by
opening the fridge door. If you keep the fridge in the car, then any
driving you do should be more than enough to get it cold again.

An idling engine 10 meters from the house will not make a noticeable
noise.

The $250 fridge and $50 inverter are probably cheaper than any
homemade solution using a vacuum.

Cooling a liter of water by one degree costs you a?kilo-calorie?(one food calorie),
assuming your cooling method is 100% efficient. The vacuum fridge you describe
will be lucky to be 10% efficient. So to cool 5 liters from 30 degrees to 7 degrees,
you need 5 * 10 * (30 - 7) = 1,150 calories of food if you want to do this by hand
using a hand pump.

Looking up the calories for various activities, we find that 1,150 calories is?
3 hours of walking briskly, or running 13 kilometers in 1 hour and four minutes.
Trying to expend 1,150 calories squeezing a hand pump with one hand will
take the better part of a day. I have one of those hand pumps, and I can pump
it for perhaps 10 minutes before my hand is too fatigued to continue. So you
will need a lot of friends to help you. But they will eat a lot, so you need a bigger
fridge, and then...

If you are going to use human power, you are much better off using a bicycle
with a generator, and powering the $250 fridge from that. It will still take 1.33
hours of bicycling.



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Get a free science project every week! ""




On Tue, Jun 7, 2011 at 11:35 PM, Slavko Kocjancic <eslavko@...> wrote:
?

S, Simon Quellen Field pi?e:
An inverter, a car, a few extra gallons of fuel, and a cheap small
refrigerator.
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During power outages here up on the mountain, I used to idle my truck
while it powered an inverter. That powered the house all day, including
a large standard refrigerator. For a little refrigerator like one of the above,
you won't need a 1,000 watt inverter -- more like 200 to 300 watts at most.
And at night, you don't need to power the fridge at all, since the door will
be closed all night.

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Well look the last link. there is cittation...
Almost all refrigerator and freezer models reviewed in this article were priced more than $1,000, with the Tundra TJ85 at $1,600, the Norcold DE-61T at $1,200, the SunDanzer DCF225 at $1,100, the Sun Frost RF-12 at $2,100, and the Sun Frost RF-16 at a whopping $2,800. You may be able to find slightly lower prices if you shop around, but all are quality-built low-energy appliances and far exceed the energy performance of lower-cost models you find locally. Since these models are fairly large and some weigh in excess of 300 pounds, they must be shipped to you by truck freight, so expect another $200 for crating and shipping costs.

And I have cabin/lodge (don't know correct english term) and running car on idle there is out of question. Possible to run inverter to run vacuum pump but not all the day for runing fridge.
using good regular fridge and inverter is cheapest. But running car to power it makes it to expensive and anyoning.
if powered with solar panel we need at least 200W panel and at least 100Ah battery. too bulky and expensive for my option.
Otherwise I want 'green' solution in my little place.


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