Solar Assisted A/C 2

[odelgado]

Greetings,

I run the energy programs for a company and recently one company came to us trying to sell us a "solar assisted" air conditioning system.

http://www.solarcool.com/Products/Commercial.aspx

I know that Lennox has solar assisted A/C units but the solar panels are used for electricity. However, these guys claim that they can get up to 32 SEER on units by using panels on the
refrigeration cycle. I am having a hard time seeing the thermodynamic logic on this. Since I don't want to appear short-sighted and brush off this technology as a scam I turn to you guys.
Have any of you seen these systems working? Do you see any logic in their claims? Any help will be greatly appreciated.

Thanks!

 

[MintJulep]

Possibly the same thing that we discussed in thread403-335360

 

[EnergyProfessional]

I think the fact that their website gives absolutely no information on how it works or what references they have says everything.

There is a cooling process that works with heating by adding moisture to a scavenger air stream, but those guys seem to claim to improve a refrigeration cycle (since they also sell AC equipment)

 

[Compositepro]

It appears to be the same scam.

 

[trashcanman]

Run, do not walk away from this outfit. You do not produce more cooling effect by "superheating" the refrigerant. The whole idea is to GET RID OF THE HEAT in the refrigerant. Thermodynamically, it makes no sense. It appears to be an exaggerated claim.

 

[berkshire]

one of these companies posted this in their how it works section,"Refrigerant is circulated by the compressor (1), to the solar panel (2), where it is heated by solar thermal energy that has been collected and stored in the panel. The heated refrigerant is now hot and at high pressure due to expansion. It enters the condenser (3), and the condensation process is now enhanced by the extra large condenser coil and the high temperature and pressure of the refrigerant. The result is that the condenser coil fills with refrigerant that has changed phase completely into liquid instead of aerated fluid as in regular air conditioners. This fluid backs up behind the choking device (capillary), (4), as it changes phase back to vapour it absorbs energy (cools), as it passes through the fan coil or evaporator(5). The cooling effect is rolled over into the air being circulated by the fan from the area to be cooled. The low pressure vapour returns to the compressor to repeat the cycle. Then in the next paragraph they say it only works with a special compressor that only they supply. I think the duck solution applies here ," If it walks like a duck etc.,".
B.E.

You are judged not by what you know, but by what you can do.

 

[MartinShane]

Any chance that they are relying on an alternative refrigeration cycle (Vapor Absorption?) and poorly communicating the process or putting marketing spin on it to cover the fact that its an old concept that is usually only going to be seen where either waste heat is very high or electricity for running a compressor would be scarce?

 

[EnergyProfessional]

yeah, heating refrigerant downstream of compressor won't increase the pressure, it will just make the compressor work harder (more electricity).

whoever buys that for his employer should get fired immediately for incompetence.

 

[Drazen]

click on mint's link, guys (eventually girls), as many things are discussed there already, and add if you have something new...

odelgado, most of us appear to be quite short-sighted on that, so you should not be worried.

the issue can be reduced to the common situation in hvac technology: some manufacturers claims new technology, presents his logic how efficient it is, but there is no real-world experience on it. it all leads to client preferences - i would say 9 of 10 of clients I am talking with would prefer proven technology, one of ten prefers brand new concepts and is ready to take risks.

explain that to you clients. you cannot take own responsibility for manufacturers claims without referent examples.

 

[HaithamMikapower]

I thinks it will help you

http://www.fafcosolar.com/go-solar/...ning/how-hybrid-solar-air-conditioning-works/

 

[IRstuff]

Perhaps it's an application of the Mpemba Effect, although I've never heard it applied to the gas/liquid phase transition

http://en.wikipedia.org/wiki/Mpemba_effect

http://www.rsc.org/images/nikola-bregovic-entry_tcm18-225169.pdf

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[Compositepro]

The explanation given in the Fafosolar.com link is complete BS. But you would need to be an engineer, or know how air conditioners work, to see that.

 

[HaithamMikapower]

i think the reduction in electricity by using little compressor than any one for the same job. almost part of condenser used for making
sub_cooling and so increase the cooling effect. i hope you to understand me as my language is Arabic. i am Egyptian

 

[Compositepro]

You cannot make a compressor more efficient by adding a heater between the compressor and condenser. The sole purpose of the condenser is to extract heat.

 

[EnergyProfessional]

that Fafosolar link is entertaining. I always thought the purpose of the compressor is to generate pressure. but to their logic it is a heating device (which they improve with solar heat).

If i wanted the condenser to get warmer gas, why would I not just make it smaller?

I must warn all the inter-cooler manufacturers that they have it all wrong and they need to built inter-heaters

why are we still discussing this? Can someone move that to the 100-mpg carburetor forum?

 

[RossABQ]

If the concept were sound, cars would use waste heat from the engine to drive the refrigeration cycle. Free A/C!

 

[urgross]

If the test was to be accurate, it would help to have CT's placed on the power supply. Sounds very much like an old topic taught in high school, application of Boyle's law. Might be why signs are posted on bridges to beware of freezing surfaces.

 

[FreddyNurk]

Looks like Choice magazine carried out an independent test that seems to confirm all of our suspicions, one that the manufacturer doesn't agree with:

http://www.choice.com.au/reviews-an...st-look-ice-solair-solar-air-conditioner.aspx

All that said, this looked interesting:

http://www.australiansunenergy.com.au/solar_airconditioning.html

given that at least some of it appears that the AC uses hot water (i.e. storage tank) as a dump load to cool the refrigerant, though I've not looked into it that much. Certainly appears to make more sense than the other stuff being discussed.

 

[IRstuff]

I doubt it, "The higher the water temperature supplied to the solar chiller, the more efficiently the cooling system will perform."

It would make infinitely more sense if the A/C were allowed to dump its heat load as a preheater to the hot water supply. Cooling something with hot water sound inane, unless one were cooling a nuclear reactor, but even then, cold water would be better.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[FreddyNurk]

IRStuff, I didn't manage to read that part, truth be told, I thought it was doing what you suggested. No chance its an absorption chiller?