Directly solar powered air conditioner - Page 5

WyrTwister · 07-23-16, 11:40 AM

A little off subject , but some old church A/C systems had a large tank of water . The chiller was run for several days & froze the water to Ice . Come Sunday , the system blew air over the ice / water tank to provide cooling / A/C for Sunday morning & night services .

In this way , " cold " was stored & the chiller could be much smaller .

God bless
Wyr

warmwxrules · 07-23-16, 03:10 PM

Quote:

Originally Posted by WyrTwister

We have a little 6000 BTU window unit . I think it pulls 6 amps . 6 x 120 = 720 watts . This does not include start up surge .

A 5000 BTU unit would pull slightly less .

What you want is not simple to implement .

God bless
Wyr

I have an 8k window ac...newer one and it pulls anywhere from 550 to 680 watts on low fan speed when the compressor kicks in. I haven't noticed a surge when watching the killawatt when it starts...although maybe it won't catch that.

I want to run it off solar panels, but i'm unsure how to make that work. I have an inverter but not sure it can handle the ac. Obviously i'd need some golf cart batteries to keep a constant supply of juice (not grid connected). Maybe next summer when i get a few more panels i'll try.

WyrTwister · 07-23-16, 05:23 PM

It will have a surge , unless it is inverter drive compressor . Like a lot of the Mini Splits . Use a clamp on amp meter and watch it on start up .

God bless
Wyr

jeff5may · 07-24-16, 10:27 PM

Nearly all of the constant speed compressors have permant split capacitor motors in them. When they start, the motor draws full LRA (locked rotor amps) for an instant until the motor starts spinning. This value is also known as stall current, and is printed on the nameplate. If you are running an inverter to power the unit, make sure it can provide at least 10 percent more peak power. Otherwise, it could trip out or burn out due to the current spike.

CrankyDoug · 07-29-16, 09:25 PM

I just purchased two LG model LW5016 5000 BTU window units from Home despot for $139 each. They each ran consistently around 400W.

This model has been around for about eight years under various brand names. I like them because they are compact and the cold air blows upward instead of horizontal. I've had at least five over the last eight years. The first two were R22 and lasted about five years before the wife decided to open the window (twice), dropping them about ten feet. The newer ones are obviously R410 and typically only last about three years. That is still cheaper than replacing a heat pump after every lightning strike.

These units run 24/7 for about six months a year. You might be able to configure one to turn on as soon as your PV's are up to 400W and have it shut down when your panels can no longer keep up.

jeff5may · 07-30-16, 08:03 AM

Another one of my wild ideas here...

I have wondered for a few years if one could run a chiller off of solar thermal collectors. Campers, caravans, and RV's have used propane burner-powered refrigeration units for decades. Why couldn't one substitute the propane burner for a sun-source heat exchanger? The COP would be high, due to the higher efficiency of thermal collection over PV. Actual electric usage would be kimited to the control system and blowers or pumps.

The technical term for this type of system is absorption refrigeration. Widely used in large industrial chillers and grocery store cabinets.

Typical tiny refrigerator:

Larger installations:

jeff5may · 07-30-16, 08:20 AM

Another one of my wild ideas here...

I have wondered for a few years if one could run a chiller off of solar thermal collectors. Campers, caravans, and RV's have used propane burner-powered refrigeration units for decades. Why couldn't one substitute the propane burner for a sun-source heat exchanger? The COP would be high, due to the higher efficiency of thermal collection over PV. Actual electric usage would be kimited to the control system and blowers or pumps.

The technical term for this type of system is absorption refrigeration. Widely used in large industrial chillers and grocery store cabinets.

Typical tiny refrigerator:

Larger installations:

mejunkhound · 07-30-16, 09:37 AM

Was wondering when someone would finally mention absorption cycle 'afore I put in some numbers.

1kW/msq solar flux nominal

array efficiency say 12%, COP of say 3 at best after inverter efficiency factored in.

1kW solar input = 0.36 kW cooling per kW of solar input via photoelectric

Absorption cycle, ammonia based, approx. 0.5 kW cooling per kW

So, you would need multijunction solar array (bigger $$) for AC to equal the ammonia cycle result.

Probably need an alum foil trough to get the temp needed though?

CrankyDoug · 07-30-16, 12:14 PM

I've never run the numbers or perused the literature, but a neighbor from the gas company once told me propane fired ammonia absorption refrigerators made efficient use of fuel. I haven't run the large Dometic unit in my 5th wheel on propane long enough to find out.

One possible issue aside from MJH's reference to the need for reflectors is the problem of consistent temperature. Focusing reflectors might solve this but at significant cost.

It looks like a good idea but not a trivial exercise. The first problem would be to secure a large enough chiller unit at scrap price.

jeff5may · 07-30-16, 01:05 PM

here is a unit produced in spain for a minute, perfect size for residential use:
Andy Schroder - About Rotartica's Absorption Chiller

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07-23-16, 11:40 AM	#41
WyrTwister Master EcoRenovator Join Date: Jun 2013 Location: USA Posts: 543 Thanks: 6 Thanked 44 Times in 38 Posts	A little off subject , but some old church A/C systems had a large tank of water . The chiller was run for several days & froze the water to Ice . Come Sunday , the system blew air over the ice / water tank to provide cooling / A/C for Sunday morning & night services . In this way , " cold " was stored & the chiller could be much smaller . God bless Wyr

07-23-16, 05:23 PM	#43
WyrTwister Master EcoRenovator Join Date: Jun 2013 Location: USA Posts: 543 Thanks: 6 Thanked 44 Times in 38 Posts	It will have a surge , unless it is inverter drive compressor . Like a lot of the Mini Splits . Use a clamp on amp meter and watch it on start up . God bless Wyr

07-24-16, 10:27 PM	#44
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Nearly all of the constant speed compressors have permant split capacitor motors in them. When they start, the motor draws full LRA (locked rotor amps) for an instant until the motor starts spinning. This value is also known as stall current, and is printed on the nameplate. If you are running an inverter to power the unit, make sure it can provide at least 10 percent more peak power. Otherwise, it could trip out or burn out due to the current spike.

07-29-16, 09:25 PM	#45
CrankyDoug Apprentice EcoRenovator Join Date: Jul 2016 Location: Georgia Posts: 100 Thanks: 6 Thanked 14 Times in 11 Posts	I just purchased two LG model LW5016 5000 BTU window units from Home despot for $139 each. They each ran consistently around 400W. This model has been around for about eight years under various brand names. I like them because they are compact and the cold air blows upward instead of horizontal. I've had at least five over the last eight years. The first two were R22 and lasted about five years before the wife decided to open the window (twice), dropping them about ten feet. The newer ones are obviously R410 and typically only last about three years. That is still cheaper than replacing a heat pump after every lightning strike. These units run 24/7 for about six months a year. You might be able to configure one to turn on as soon as your PV's are up to 400W and have it shut down when your panels can no longer keep up.

07-30-16, 08:03 AM	#46
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Another one of my wild ideas here... I have wondered for a few years if one could run a chiller off of solar thermal collectors. Campers, caravans, and RV's have used propane burner-powered refrigeration units for decades. Why couldn't one substitute the propane burner for a sun-source heat exchanger? The COP would be high, due to the higher efficiency of thermal collection over PV. Actual electric usage would be kimited to the control system and blowers or pumps. The technical term for this type of system is absorption refrigeration. Widely used in large industrial chillers and grocery store cabinets. Typical tiny refrigerator: Larger installations:

07-30-16, 08:20 AM	#47
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	Another one of my wild ideas here... I have wondered for a few years if one could run a chiller off of solar thermal collectors. Campers, caravans, and RV's have used propane burner-powered refrigeration units for decades. Why couldn't one substitute the propane burner for a sun-source heat exchanger? The COP would be high, due to the higher efficiency of thermal collection over PV. Actual electric usage would be kimited to the control system and blowers or pumps. The technical term for this type of system is absorption refrigeration. Widely used in large industrial chillers and grocery store cabinets. Typical tiny refrigerator: Larger installations:

07-30-16, 09:37 AM	#48
mejunkhound Apprentice EcoRenovator Join Date: Apr 2011 Location: PNW Posts: 197 Thanks: 0 Thanked 47 Times in 31 Posts	Was wondering when someone would finally mention absorption cycle 'afore I put in some numbers. 1kW/msq solar flux nominal array efficiency say 12%, COP of say 3 at best after inverter efficiency factored in. 1kW solar input = 0.36 kW cooling per kW of solar input via photoelectric Absorption cycle, ammonia based, approx. 0.5 kW cooling per kW So, you would need multijunction solar array (bigger $$) for AC to equal the ammonia cycle result. Probably need an alum foil trough to get the temp needed though?

07-30-16, 12:14 PM	#49
CrankyDoug Apprentice EcoRenovator Join Date: Jul 2016 Location: Georgia Posts: 100 Thanks: 6 Thanked 14 Times in 11 Posts	I've never run the numbers or perused the literature, but a neighbor from the gas company once told me propane fired ammonia absorption refrigerators made efficient use of fuel. I haven't run the large Dometic unit in my 5th wheel on propane long enough to find out. One possible issue aside from MJH's reference to the need for reflectors is the problem of consistent temperature. Focusing reflectors might solve this but at significant cost. It looks like a good idea but not a trivial exercise. The first problem would be to secure a large enough chiller unit at scrap price.

07-30-16, 01:05 PM	#50
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	here is a unit produced in spain for a minute, perfect size for residential use: Andy Schroder - About Rotartica's Absorption Chiller