Ya, I did the calculations using my cost per KWh of 12.1 cents. We recently had a cost reduction of about 1 cent per KWh. Yea! I made the assumption you would use the air conditioner 2 hrs a day for
6 months of the year. I got a yearly expense of $48.89. It's a shame electricity is so cheap, or not! Mikek
Build your bedroom in the form of this fridge.
Mikek
Ummm... that evaporative fridge is a bit small to crawl inside. Basically, it's a small swamp cooler.
At one time, I owned a Land Rover. I noticed that the models used in Africa had a double roof for cooling. I decided that it might be possible to do something similar with a typical home shed roof. I convinced a friend to try it (my roof is almost flat) using white painted plywood and about a 3.5" air gap. It worked. The problem is that the roof is one of the most expensive parts of a house, and double roofs will make it even more expensive:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Are you sure? Do you mean "power", or do you mean VA? Lots of VA at low RPM (except for losses), but less power. And, it doesn't last long. I doubt it takes more power to start than to run.
Yes, you're right. Takes more amps to start a compressor than to run it. I've never tried to measure the starting VA vs starting Power. And we've not discussed the potentially significant (power) factor that inverters are likely rated in power into a resistive load. Running a motor ain't resistive.
But, your nitpicking is missing the point of the exercise. It's gonna take an inverter (system) with a LOT more peak capability to start a compressor than to run it. Matching what it says on the air conditioner name plate is likely to result in failure.
An inverter that switches off to protect itself from the start transient or worse, lets the smoke out, isn't gonna be very useful in this, or any application.
'Roofover' is a common conversion in Florida. Foam insulation and interlocking aluminum troughs, along with the mounting hardware & trim is a common addition over a low pitch roof. Another is called 'Peel & Stick' by the installers. It costs more, but it's four inch thick foam panels with an aluminum skin bonded to both sides. They are T&G to hide the mounting hardware, and allow the seams to be calked shut. The ends & sides are covered with matching trim.
So, the low impedance start windings are imaginary?
Almost all home sized synchronous inverters consume at least 150 percent of the value of the electricity sent through them.
More at <
-- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
Developed as early as 1890 in Coolgardie Western australia. See
Works much better in a breeze and is only impeded by sunlight which provides the heat that, in truth, should be drawn from the contents
-- John G
Can you explain how this works? I can understand how a breeze can cause evaporation cooling the contents as low as the dew point. But the article describes how the sun's rays cause the evaporation. Can't see how the "rays" do anything helpful?????
Who are you asking?? The link I provided describes it clearly and also mentioned a water bag to carry outside your vehicle to have water cooled the same way.
You are correct, the suns rays will not contribute at all and in fact will reduce the effectiveness. ;-)
-- John G
Consider an evaporative cooler.
--Winston
begin.
Check this out:
Here is a homemade swamp cooler:
Here's a complete off-grid cabin with 12V appliances:
You could use a Peltier effect cooler. Here is a 150 BTU/hr (12V 4A 48W) =
unit for $30 plus $13 shipping. Get 10 of them for 1500 BTU/hr. You = might be=20 able to combine these with a swamp cooler by thermally connecting the = hot=20 plate to the water. You pay for the difference in temperature, so with = cold=20 water you'll have a lot colder air (or better heat removal, actually) = for=20 the same cost.
Actually you might be able to use a dorm size refrigerator or a 12V = camping=20 fridge and stick it in a window with the door open and a small fan = running.
Finally, it might be possible to get a car or truck air conditioning = unit=20 and drive the compressor with a DC motor.
Sometimes you just gotta think outside the (ice) box! :)
Paul
Here are 60W Peltier cooling plates for $4 each with free shipping. 200=20 BTU/hr. 25 of them would (should) give you a 5000 BTU/hr A/C for under = $100.
These are more believable (and complete units with heat sinks). $38 each = for=20
70W or 170 BTU/hr. They are selling 24 pieces for $35/each. So for $840 = you=20 would have a nice 4000 BTU/hr A/C. I don't know the efficiency, but it's =probably a lot better than going through a solar power inverter and then = an=20 AC motor and compressor.
Paul=20
I'm curious if this concept could be pushed further, with modern material and technology. Just to throw out an idea, a very well insulated room with a pipe running in the center of the room vertically to the ceiling, then horizontally to the outside down to the ground then back to the center of the room. Circulate a liquid through the pipe. On the outside the pipes use the evaporation concept to cool the liquid which circulates to the center of the room. The pipe/evaporation scheme would be duplicated as many times as required for the room. I wonder if the liquid could be self circulating just by temperature difference alone. Are there materials that could be used for the evaporative sheets that are more efficient. In the end it's a swamp cooler, but we don't want the evaporated moister inside the room, we do want the cooled liquid in the pipe circulated into the room. Your ideas welcome. Mikek
Dias Analytic
has a process that uses a membrane to suck moisture out of the air without condensing it or changing the temperature. Then they put the air thru a swamp cooler to cool the air and put the moisture back. A year ago, they had the DoE interested enough to give them a bunch of $$$$. But the steady decline in stock price suggests that things may not have gone so well since.
If you have a hot area and a cold area, you can move the heat from one area toward the other. Normal technology requires some kind of heat exchanger. The problem is that the hot area is typically higher in elevation than the cold area. Efficient heat exchangers, like heat pipes, work better moving heat upward. That requires some motive power to reverse that process.
I've made some heat exchangers for a heat recovery ventilator using copper pipe and freon. The pipes work amazingly well. Problem is getting the heat from the air into the pipe with stuff you can build in your garage. Suggestions welcome.
For air to air exchange, DIY units made out of Coroplast give a lot of bang for the buck. Would be interesting to try to make an air to water one. Would take a LOT of caulk to patch up all the leaks. Or just use a car radiator.
Bottom line is that your best investment is insulation. If you have EXCELLENT insulation, simple schemes like pumping water around have a better chance of working, but the amount you save is small. Do the math. Takes a LOT of water to mediate the daily temperature change, even if you do have the right climate for it.
If you do the math, it's likely that anything you do with retail cost parts isn't cost effective. It then becomes a hobby exercise in what you can do with what you have on hand or available for free.
The problem has two loosely coupled parts, so let's separate them.
1)How do I cool the bedroom? If you need to move heat from one place to a hotter place, it's hard to imagine anything more cost effective than the air conditioner he already has. Peltier is a very bad solution for anything without severe restrictions...like cooling something that puts out no power to very cold temperatures...thermal imaging... or something that can't have any moving parts. Yes, sometimes it's handy to be able to drink warm pop in the car instead of hot pop, but it ain't efficient.If you have a heat sink at a colder temperature, you may be able to do something with a heat exchanger.
2)How do I power it cost-effectively with solar? You don't!
Well, it might be expensive to air condition the entire room, but he could build a space suit, and pump chilled water through vinyl hoses between himself and the space suit. Cool the user, not the house.
Of course, there are complexications. Dragging a supply hose and ice bath around the house is not going to be very practical. A portable A/C will just add more heat into the room, while cooling the user. I suggest a portable ice bucket and circulation pump to carry around. The ice machine can be outside or in the garage to keep the waste heat from becoming a problem.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
There are personal cooling vests and suits:
You could probably make chilled water and circulate it through tubing = and=20 thermally conductive pads placed on various parts of the body to feel=20 cooler. Sort of the reverse of a diving heater:
Paul=20
And that is even true for off grid provided that there is some relatively easy way to carry a suitable battery to and from the site.
Wind turbines are a little bit better - you might at least hope to get enough electricity out of one of them on a good day to power A/C though there is still a very hefty capital investment to do so.
Best you can do for a small room is put a scacrificial thin shade layer on the sun facing walls and follow the sorts of ancient building codes with verandas and shutters to keep heat out during the day. Cacti and termite mounds demonstrate most of the requisite engineering tricks.
Using modern advanced insulating materials like aluminium foil backed bubble wrap and the equivalent in thick glass fibre insulation you can prevent a lot of heat getting in from the roof space. Preventing the heat getting inside is better than struggling to remove it later.
Regards, Martin Brown
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