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I am ALWAYS thinking of energy (and how to use less). I'm planning on heating my house with evacuated tube solar thermal panels and radiant heat flooring. This got me thinking of what it can be used for in the summer (OTHER than domestic hot water).

If an air conditioner compressor heats freon as it compresses the gas, based on ideal gas law, if you heated the freon, shouldn't that also compress it? What is the average temperature of the freon after it is compressed? Would something like this be feasible? I'm wondering why this hasn't been explored more? I've found a few articles about companies making prototypes, but no commercially available units. If I'm not mistaken, the compressor it the most energy consuming part of an air conditioner, so this could dramatically reduce energy demand in the summer.

Has anyone done any tinkering along these lines or have any knowledge on the subject?


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`86 Volkswagen Jetta NA: 9 Gallon Marine Tank>Transmission Cooler Tank Heater>TIH>FPHE>Coolant Wrapped Veg Filter>2, 3 Port Hydraforce Valves>Temp. Probe>Line Heater Specialist Injector Line Heaters>Vegtherm on Return>"Crud Catcher">Loop

Everyone Should Read "Ishmael" by Daniel Quinn
 
Location: Woodstock, IL | Registered: May 28, 2006Reply With QuoteReport This Post
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Has anyone done any tinkering along these lines or have any knowledge on the subject?

I'm not clear about the connection with the solar panels and the air conditioning system. When the refrigerant gas is compressed its changing from a vapor to a liquid ,thus its condensing and giving off heat. As long as the pressure is high enough we cause the vapor to go to a liquid state. Once the liquid passes thru the metering device it gradally changes back to a vapor on the low side of the system and enters the evaporator coil to conpletely go to vapor this is where heat is absorbed.
There are heat pump systems that function this way and can do both heating and cooling . They have a reversing valve so the functions of the condenser and evaporator can be reversed. I believe they can be used to extract heat from water . This is probably where you are applying the solar panels.
The pressures vary depending on the refrigerant gas thats used,usually 100 -250 psi. R410 systems can go over 400 psi.
 
Location: western new york | Registered: November 19, 2008Reply With QuoteReport This Post
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Look into the old Servel air conditioners. They were gas-fired... as in natural gas. It's the same idea as a refrigerator in a camper. Rather than use a compressor, it uses heat to drive the process.

Also, check out Robur. I think they may now own the old Servel brand name. Here's a page on it:
http://www.gasairconditioning....obur_description.htm

Down here in the Deep South, humidity is a big problem. I looked into desiccant dehumidification as a way to lighten the load on cooling but the temperature required to regenerate the desiccant material is way higher than I can see generating easily with solar means.

I'm confident that we can come up with some creative ideas, though. I've had chemical engineers scoff at the idea of running my truck on heated waste veg oil... until I put a couple of hundred miles on my truck doing it!


2002 F-250, 7.3l on WVO since '04
'82 VW Rabbit diesel 1.6l na
'83 GMC 6.2l Class C RV
'85 F-350, 6.9l flat bed
'85 E-350, 6.9l cube van
2 Mercedes 300SD's
3 Chinese Changfa-style diesel generators- 12kw, 8kw & 7.5kw
Mitsubishi 3 cyl diesel generator/light tower
Kubota 2 cyl. diesel, water cooled air compressor
Onan 12.5kw air-cooled diesel genset
I run my company entirely on renewable energy including electricity from generators running on biofuels.

 
Location: El Dorado, Ark | Registered: July 04, 2004Reply With QuoteReport This Post
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This page even talks about solar heated water as a source for chilling:
http://www.energysavers.gov/yo...ex.cfm/mytopic=12680


2002 F-250, 7.3l on WVO since '04
'82 VW Rabbit diesel 1.6l na
'83 GMC 6.2l Class C RV
'85 F-350, 6.9l flat bed
'85 E-350, 6.9l cube van
2 Mercedes 300SD's
3 Chinese Changfa-style diesel generators- 12kw, 8kw & 7.5kw
Mitsubishi 3 cyl diesel generator/light tower
Kubota 2 cyl. diesel, water cooled air compressor
Onan 12.5kw air-cooled diesel genset
I run my company entirely on renewable energy including electricity from generators running on biofuels.

 
Location: El Dorado, Ark | Registered: July 04, 2004Reply With QuoteReport This Post
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Thanks for the replies and links!

Heatbeater: The connection between the solar THERMAL panel and air conditioner is as follows. An air conditioner works by a moderately temperature freon GAS is compressed by the compressor. The now high pressure and high temperature freon GAS (ideal gas law temp/pressure is related proportionally) and continues to become a high pressure liquid etc... Since temp/pressure is proportional, if you heat the gas its pressure should also increase. If you were to remove the compressor from an air conditioner and instead add a heater (in this case the heat would be from evacuated tube solar thermal panels which can get VERY hot in the summer) you could some how achieve the same result. To make this feasible is what i'm curious about.

Does anyone know approx. what temp. the freon is after it is compressed?


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`86 Volkswagen Jetta NA: 9 Gallon Marine Tank>Transmission Cooler Tank Heater>TIH>FPHE>Coolant Wrapped Veg Filter>2, 3 Port Hydraforce Valves>Temp. Probe>Line Heater Specialist Injector Line Heaters>Vegtherm on Return>"Crud Catcher">Loop

Everyone Should Read "Ishmael" by Daniel Quinn
 
Location: Woodstock, IL | Registered: May 28, 2006Reply With QuoteReport This Post
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hmmmm..... looks like "solar absorption chiller" is basically what I am envisioning. It doesn't, however, look like there are any commercial models available for a smaller house sized application. Anyone else know of any? Seems like a GREAT idea! The hotter it gets the better they work, plus they are not generating any MORE heat(A/C compressor) on an already hot day.


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`86 Volkswagen Jetta NA: 9 Gallon Marine Tank>Transmission Cooler Tank Heater>TIH>FPHE>Coolant Wrapped Veg Filter>2, 3 Port Hydraforce Valves>Temp. Probe>Line Heater Specialist Injector Line Heaters>Vegtherm on Return>"Crud Catcher">Loop

Everyone Should Read "Ishmael" by Daniel Quinn
 
Location: Woodstock, IL | Registered: May 28, 2006Reply With QuoteReport This Post



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If you eliminate the compressor and use heat from the solar panel to bump the pressure of the refrigerant gas which in turn will be released at the condenser your evaporator will have to be near the solar panels. It still seems like a compressor would be more efficient. This might be possible with the right type of refrigerant or the ammonia system,but your also looking for a place to efficiently use the heat in the summer.
I my opinion you need to know how many btu's/hour your solar panels produce on the average summer day to be able to find a use for the access heat. At one time I was thinking of using solar for heating my wvo for biodiesel.
Check www.refrigerant pressure/temperature charts.
 
Location: western new york | Registered: November 19, 2008Reply With QuoteReport This Post
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Originally posted by -wewantutopia-:
Does anyone know approx. what temp. the freon is after it is compressed?


The hot freon is from compression... and is why the outside radiator part of an AC unit blows out hot air.

Heating the freon would be counter-productive and would just make it harder to liquefy.

Although, I guess I'm imaging a system that could run in heating/cooling stages essentially using the heating as a diaphragm-less pump. Heat some of the freon to pressurize freon further down the system in the cooling coils, then release the liquefied freon, cool what you just heated and recharge the system... and repeat the cycle.

The absorption/adsorption refrigerants use two liquids (or a liquid and a solid) to do the process.

The heat is used to essentially distil pure ammonia out of water under moderate pressure. This pressurized ammonia can be re-condensed at room temperature.

I believe the water absorption phase lowers the vapor pressure of ammonia to cause better cooling... or something like that. You can look up the cycle.

Ammonia is mildly toxic, but very noxious, so the toxicity is probably overrated, and a leak would be quickly detected.

However, there are other types of absorption media such as Water/Lithium Bromide (I think) which might be better suited to solar power.

You may also look at other more passive cooling systems.

I spent some time in Missouri. Usually it would cool off in the evenings. So, if I was comfortable at work, I could cool the house with a good window fan, or something similar.

But, I've also considered burying cooling pipes 6-foot under (or so), which should be adequate to get geothermal cooling (and perhaps a good input for a heat pump in the winter too). There are lots of discussions about a "heat chimney" which can cause a draft.

You will find some interesting discussions on the website:

http://www.fieldlines.com
 
Location: Oregon | Registered: October 17, 2007Reply With QuoteReport This Post
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The hot freon is from compression...


Right. I'm just thinking of ways to remove the compressor, the part of the A/C with the greatest power demand and source of added heat during the already hot summer.

If the volume remains the same, increasing the temperature of a gas (freon) will also increase its pressure. I seems you should be able to heat the freon and achieve the same effect as if it ran through a compressor. The required temperature to heat the freon to the required pressure is what I should really be asking about.

My house already has a great deal of passive solar properties: large south facing front porch, large deciduous shade trees on the south side of the house, and an overhang large enough to block direct sun in the summer of the 10' wall of south facing window. Also, I plan on burring geothermal cooling loops when we dig a driveway in the next 2 years.

I guess this is an abstract thought meant for discussion to find a new lower energy solution to a problem.

Thanks for the link and reply!


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`86 Volkswagen Jetta NA: 9 Gallon Marine Tank>Transmission Cooler Tank Heater>TIH>FPHE>Coolant Wrapped Veg Filter>2, 3 Port Hydraforce Valves>Temp. Probe>Line Heater Specialist Injector Line Heaters>Vegtherm on Return>"Crud Catcher">Loop

Everyone Should Read "Ishmael" by Daniel Quinn
 
Location: Woodstock, IL | Registered: May 28, 2006Reply With QuoteReport This Post
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I've been looking into this for years. Sadly, thanks to increased efficiency measures, my house no longer needs the smallest sized Robur system... a 5 ton AC. There is no question of "Will it work?" The question is of affordability. The market demand just isn't enough to get production numbers high enough to drive down the price.

A few years ago, a friend who at the time was a chemist for a state department of environmental quality judged a high school science fair. A young lady designed an expansion valve and solar heating/cooling system that worked quite well. She used a fresnel lens as her heat source. Worked great! My buddy said Fedders bought the license to it.

My hope is that enough of us can become interested to do the same thing we have done with WVO and biodiesel. We couldn't find small scale biodiesel systems... so we built our own. The auto manufacturers didn't offer a two tank heated WVO system... so we built our own.

Reading up on Ammonia cooling systems, it seems the talk of danger is over-rated. It's like running a generator... don't put it inside the house and make sure it is in an area with good ventilation. I have a friend who used to own an ice business who put one in his new home a few years ago... works great. But again, his house is large enough to need quite a few tons of AC capacity.

Ground tubes seems awfully promising, too. I still question the humidity issue, though. Maybe that's where desiccants come in.


2002 F-250, 7.3l on WVO since '04
'82 VW Rabbit diesel 1.6l na
'83 GMC 6.2l Class C RV
'85 F-350, 6.9l flat bed
'85 E-350, 6.9l cube van
2 Mercedes 300SD's
3 Chinese Changfa-style diesel generators- 12kw, 8kw & 7.5kw
Mitsubishi 3 cyl diesel generator/light tower
Kubota 2 cyl. diesel, water cooled air compressor
Onan 12.5kw air-cooled diesel genset
I run my company entirely on renewable energy including electricity from generators running on biofuels.

 
Location: El Dorado, Ark | Registered: July 04, 2004Reply With QuoteReport This Post
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I looked into ground tubes a while back. There are two types. The one everyone knows about uses them as a heat sink for a condenser.

The other is more interesting. Drawing air through burried tubes to cool them. Works OK up north where they don't have our high humidity. Down south they need some help to work. Our water table is about 75 feet down. Here we can push (drive) a well casing into the ground without drilling, so wells are cheap here. I thought I could use cold well water as a coolant either directly or indirectly.

The other method is to use heat pipes for both humidity control and as a heat exchanger on the exhaust air.

I never worked up anything. I did find some examples on the web. I doubt I could find them again.

Rick
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post
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The Matteran Energy Corporation Has been working on a system using low temp heat to produce electricity as well as air conditioning, they heat a refrigerant in a boiler section and then pass the pressurized vapor through a small turbine to produed electricity and/or pass the pressurized liquid refrigerant through an orifice to expand into vapor and absorbe heat, the spent vapor from either process is cooled til it condenses, moved into a seperate heatable container, heat is added and the pressure produced plus head pressure from gravity is used to again inject the condensed liquid refrigerant back in to the boiler.

The process is interesting and I suspect it can be adapted for use with higher temp direct solar heat. These folks have been around for several years, they have patents and some prototypes but it appears to mostly be a bit of a scam to draw investment money?

I have been toying with this solar power/cooling idea also in this Organic Rankine Cycle discussion.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post



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Does anyone know approx. what temp. the freon is after it is compressed?



I used to measure the temperature at the point that the gas want into the condenser on the refrigeration plant at my works. It was around 85c on the outside of the pipe.

Don't forget that you need to create a low pressure situation in your evaporator for the system to work. The compressor does this for you.

dva
 
Location: Yorks,England | Registered: June 30, 2001Reply With QuoteReport This Post
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Need a bit more info on just what is meant concerning the temp, the temp will be different for every system and weather temp. Condensing the freon (freon is a specific working fluid, are you actually using "freon", each type working fluid has a different temp/pressure profile) is a combination of pressure and temperature, the hotter the workinmg fluid is the more pressure it will take to condense it, this is why you want to use as much radiator surface area cooling as practical, more cooling needs less pressure. The relationship of pressure to temperature is a direct ratio, if you know the specific working fluid and it's temperature you can look up the pressure without actually having to measure it.

Search the web for Pressure/Temperature tables for each of the specific refrigeration fluids you are interested in, they are available free on MANY websites.

I don't have numbers on condensing freon but I did take data on condensing propane using a modified 5000 BTU window air conditioner (removed the restrictions in the tubing), I drew propane vapor from the top of tanks, the propane vapor first flowed through the outside radiator of the air conditioner, then through the compressor, then through the indoor radiator, then into a 100 pound propane tank.
In normal 80 beg f summertime temps the pressure needed to condense the propane was 375 to over 400 pounds using just the air blown through the small radiators by the normal fans inside the air conditioner, if I added a fine water spray through the radiators I could drop the required pressure down to under 300 pounds, if I also sprayed the outside of the condenser tank with water I could get thew pressure down around 225 pounds.

It was interesting to watch slugs of compressed vapor condense into liquid in the collection tank, the pressure gauge would rise slowly to some pressure than instantly drop down several pounds when a slug of vapor would suddenly condense into a much smaller volume of liquid and cause the pressure to drop til more vapor was pumped in to replace it.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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I was wondering the approximate temperature of freon after it is compressed to get a rough idea if solar thermal would be hot enough to reach the pressure needed. (since heat and pressure are proportional). Sounds like it is.

I envision an "air conditioner" without a compressor or any mechanical parts. Heat freon (or other more appropriate working fluid) in a constant volume to reach the same pressure achieved after it is compressed by a compressor. The rest of the a/c would be the same.

Just toying with ideas...


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`86 Volkswagen Jetta NA: 9 Gallon Marine Tank>Transmission Cooler Tank Heater>TIH>FPHE>Coolant Wrapped Veg Filter>2, 3 Port Hydraforce Valves>Temp. Probe>Line Heater Specialist Injector Line Heaters>Vegtherm on Return>"Crud Catcher">Loop

Everyone Should Read "Ishmael" by Daniel Quinn
 
Location: Woodstock, IL | Registered: May 28, 2006Reply With QuoteReport This Post
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if I added a fine water spray through the radiators I


In summer we used to spray water over the concrete bases beneath the condenser units. As the draft was upward through the units this made quite a difference.
Condensers just love cold clear winter nights.

dva
 
Location: Yorks,England | Registered: June 30, 2001Reply With QuoteReport This Post
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Most cooling devices that work from heat seem to produuce either ice or cold water, there are commercial "chiller" units that use the same burner that is used in heavy oil burning heaters, basically a modified Beckett burner.

I have found a couple links to solar powered absorbtion ice makers, these use Ammonia and cycle between the sun in the daytime to heat the system and then they freeze water during the cool night, they only produe ice once a day during the night - but they apparently do work.

The ones linked to below are small test units that only make a few pounds of ice per day but they could be scaled up. These do not use a compressor but move the fluid by temperature differances between day and night,

This first link is to a patents page describing several systems and referancing research papers.

http://www.rexresearch.com/interefr/patents.htm

The next link is to a San Jose State Univ research project. There likely is more info on the univ website but I have not yet researched it.

http://hackaday.com/2008/08/29...r-powered-ice-maker/

There used to be a Homepower magazine PDF article describing a similar intermittent ammonia solar ice maker, A web search finds referance to it but the links I have found no longer work, I have the article in PDF form saved from the past but I have not yet found a wcurrent orking web link.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post
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Found THIS LINK to a commercial absorbtion water chiller that can also use solar heat, 10, 20, or 30 ton capacity.
 
Location: fisher,illinois,usa | Registered: June 03, 2003Reply With QuoteReport This Post



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