How Your A/C and Fridge Work

Air conditioning, fans, and anything related to keeping it cool, such as insulation. This would include any posts generally discussing how to keep it cool, such as which types of blocks are better insulators.... ideal wall thickness for keeping an A/C house cool, etc.

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How Your A/C and Fridge Work

Postby Itchy » Mon Sep 05, 2005 9:07 pm

Here's a tutorial on Heat Pumps, or what we more commonly know as A/C Units and Fridges.
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heat pump running with solar power?

Postby Attila » Tue Sep 06, 2005 8:52 am

Thanks, Itchy!

This is reminding me of the old days in a colder country, where heating with a heat pump was discussed a lot.

Let me add also that the cooling system works also to cool water, instead of air. A heat exchanger cooling water might even be more efficient, as water takes the heat / cold more quickly.

This way the cooling system having cold water pipes in your wall / ceiling / floor, which I described in another thread here, can get cooled. I wonder if some solar panels would give enough power to run such a heat pump.

Then the system would, after the installation costs are paid.
be cooling for free forever :D and
without having to import more oil :D :D and
without pollution :D :D :D
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Postby Itchy » Tue Sep 06, 2005 1:06 pm

The problem with having cold water pipes in your ceiling/walls/floors is the condensation that collects on the a/c exchager fins is now going to collect on your ceiling/walls/floors.

The cost of electricity from solar cells is still very high, and as we all know from our electricity bills a/c units use a lot of electricity, so you would need a lot of solar cells.

The polution issue is not quite so simple either, because solar cells contain heavy metals, which have very long term environmental impact arrising from production and disposal after use.

A far better solution is to opt for 'Passive' heat control methods, such as ventilation and insulation - I'll do some sheets on these later.

Itchy
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Postby Attila » Tue Sep 06, 2005 5:12 pm

Itchy wrote:The problem with having cold water pipes in your ceiling/walls/floors is the condensation that collects on the a/c exchager fins is now going to collect on your ceiling/walls/floors.


It would be interesting to see this effect in a live and working system. There is the much bigger surface, which might help to make condensation not such a problem as it is with a conventionell a/c

Itchy wrote:The cost of electricity from solar cells is still very high, and as we all know from our electricity bills a/c units use a lot of electricity, so you would need a lot of solar cells.


Absolutely, yes, it would be very expensive to try to install enough solar panels to feed a conventionell a/c. My speculation is based on the assumption that such a water cooling system would run with much less energy, making full benefit of the heat pump. I will see if I find real values for the energy consumption of such a system.

Itchy wrote:The polution issue is not quite so simple either, because solar cells contain heavy metals, which have very long term environmental impact arrising from production and disposal after use.


The batteries probably also do contain some problematic elements. Now let's see that with a background of 10 years usage for the batteries and 25 to forever for the panels. Compared to burning oil the balance might be still very positive for the solar power.

Itchy wrote:A far better solution is to opt for 'Passive' heat control methods, such as ventilation and insulation - I'll do some sheets on these later.

Itchy


I look forward to reading them :D

Yes, the best, cleanest and cheapest is to avoid the need to use energy in the first place. Only where this would not be sufficient a energy consuming cooling system should be considered. It works fine, as my current house shows, I never switch on the a/c, but use the ceiling fans and open windows, and feel fine this way. :D
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Postby Itchy » Tue Sep 06, 2005 5:31 pm

My office here in Rome has embedded cooling, Believe me, if I leave my office door open or worse still open a window, the ceiling starts dripping water within about ten minutes.

To see how much water condenses out, next time you've had your a/c off for a day or two put a bucket under the a/c unit's water drain pipe before you switch the a/c on and then go check in about an hours time how much water has condensed out. - It's a lot of water!
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Postby Attila » Tue Sep 06, 2005 8:11 pm

Itchy wrote:My office here in Rome has embedded cooling, Believe me, if I leave my office door open or worse still open a window, the ceiling starts dripping water within about ten minutes.

To see how much water condenses out, next time you've had your a/c off for a day or two put a bucket under the a/c unit's water drain pipe before you switch the a/c on and then go check in about an hours time how much water has condensed out. - It's a lot of water!


And for a millisecond it was there, the crazy thought that this could be the solution to Pattayas water problem :wink:

Point noted about the dripping water, this could indeed be a show stopper.

How about the feeling in your office, do you feel a difference to the blowing cold air in your face a/c's?
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Postby Itchy » Wed Sep 07, 2005 1:12 pm

Yes, I much prefare the coolness without the air blowing in my face. In our Thailand office I often had dry eyes from the constant drafts.

But nothing man made matches the cool September mornings as I walk to the tram stop of a morning!!
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Postby cruzing » Wed Sep 07, 2005 9:30 pm

Itchy wrote:But nothing man made matches the cool September mornings as I walk to the tram stop of a morning!!


ain't it the truth :!: I sure miss my hometown this time of year. (sorry ot)
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Postby Attila » Tue Sep 13, 2005 11:19 pm

Itchy wrote:...
The polution issue is not quite so simple either, because solar cells contain heavy metals, which have very long term environmental impact arrising from production and disposal after use.


Hi Itchy,

since I ordered solar cells for my house, I did think about this info from you. And worry a lot! :? :? :?

Now I have good news. The heavy metal problem is a thing of the past technologies. Modern solar panels, such as the ones from RWE seem to have solved it:

http://www.us.schott.com/architecture/english/products/bipv/technicaldata.html wrote:The ASI? Solar Cell Technology- optimized for building integration:
- Converts sunlight directly into electronic power
- Thin film coating less than 1 micron thick
- The solar cells are 99% silicon and free from cadmium and other heavy metals


Now that's good news, isn't it! :D
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Postby The Dude » Fri Mar 02, 2007 2:50 pm

Itchy,

I think your explanation is half baked! :? You need to understand the laws of "Thermal Dynamics". Especially, the principal of "Heat Exchange" primarily rule number 3. I would be more than happy to explain it the next time I am in LOS over a beer. My back round is engineering (mechanical) for HVAC systems primarily in large facility operations with Boilers and Chillers as well as "Building Automation" with PLC and DDC controls.

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Postby Itchy » Fri Mar 02, 2007 7:11 pm

I don't mind a few beers, but please leave the lectures on Thermodynamics out, I had enough of those at university.

So did our HVAC engineer, I've just run my explanation and he seems to think its fine. He rather liked it.

But how about improving it.... That would be good.

I always like to see improvements and other people's ideas. Afterall, I'd hate my HVAC post to get the 'Blank Paper Syndrome' that my electrical posts sufferd.

'Blank Paper Syndrome' = The curious ability for people to sit all day looking at a blank piece of paper and offer no comment/suggestion/idea. Only to suddenly burst into criticism when someone else puts an idea on the paper.

Anyway, beers sound like a good idea... cold I hope.
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