Hybrid Solar Air-Conditioner

Please look for your answer in these links.

working principle of Hybrid Solar Air-conditioner

It does not explain it. After compression, how does adding heat will improve efficiency. It should lose heat and condense, followed by evaporation!

you can google ammonia chillers and see a few examples. there are AC systems out there that use natural gas to burn a burner rather than a mechanical compressor, I know it sounds odd at 1st but its an old method it's an absorber chiller, Arkla and Panye have made these for residential use

I don't think absorption mechanism is used here, otherwise , it will be hugh. The puzzling thing is , in compression A/C, after compression, the refrigerant should lose heat and condense. But here they say, solar heat is added ! then condense then evaporate. How does that improve efficiency?

you have to move the gas through the condenser...the added heat does that

"you have to move the gas through the condenser...the added heat does that"

NO! Pressure does that. According to the link provided, this is NOT anything like an ammonia system. I totally agree with Bravo88; adding heat after the compressor increases the pressure, so the compressor will have to work HARDER, not less. Then the compression heat AND the added heat must BOTH be eliminated by the condenser.

Unless there is some new physics here that they are not telling us, THIS IS A SCAM!

Since the web site says it use R 717 (Ammonia and water) it is an absorption system. You said it was a small system. The web site also said the minimum size is 5 ton. There were MANY 4 and 5 ton absorption systems used in the USA in the 60's and 70's. Day and Night and Arkla were the 2 I saw most. They were more expensive to produce and so fell out of favor in the early 80's -- JHF

Which web site are you referring to?. I did not see any reference to the working fluid in the original link...

I can't seem to find it right now, but it was refered to in one of the posts. I'll try to find it and send it to you after while, a little under the gun for ime right now! -- JHF

I still have not been able to find the site I found yesterday. I started with alibaba.com and it sent me to a site that showed a split system and mentioned sizes from 5 to 200 tons and refrigerant MR-717. Since then I have seen a bunch of hybrids that say they use a dc solar assisted compressor and a bunch that show a picture of what looks like a tank mounted above a window a/c unit. They mention R-22 or 410a. I, like you, can't see how adding heat can improve effency. Hocus pocus with the numbers! -- JHF

Agreed!

The link contains this graphic:

There may be other pages at the site; if so, I did NOT see them.

I just now noticed that it says "Solar Compressor" whatever that may be...

In compressing a gas heat is generated. In heating a gas pressure is generated. In reducing the pressure the compressor needs to work at and adding heat from the solar collector to maintain the pressure necessary for the gas to condense in the condenser will save energy.

If you compress less and add heat , the refrigerant will be more difficult to condense! So, Your explanation does not explain it.

A quick explanation taking up several lines is not going to do it here. The principals do not need to include "hybrid and solar". What you need is "air conditioning 101". There are many, many, books written on this subject, and also full courses of study available. I also found a wealth of free information on the web.

Even if this scheme works, none of the explanations I've seen so far are clear, and some include doubtful information. Maybe the fluff conceals the real (proprietary) goodies?

all so9lar pitches have "fluff"!!

You got my point exactly.

When I was a kid, we had a small travel trailer that had a propane refrigerator. I was amazed. My father explained it's operation to me. I was still amazed. In fact, I'm still amazed today.

http://www.thenakedscientists.com/forum/index.php?topic=23436.0

So, you can use the sun in place of propane, maybe.

http://www.scientificamerican.com/article.cfm?id=solar-refrigeration

However, there are other ways:

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

Did you look a the link provided in the original post? All of your links are referring to absorption type refrigerator systems. This is NOT an absorption type system! As I said in an earlier post, lacking some new physics, this is a SCAM!

If I did not find that China manufacturers already already producing them by the thousands , I would also dismiss it as scam. But I think it is not scam, that' s I post the question, it is certainly interesting from point of view of physics and engineering.

Is this a mental exercise, or do you have a vested interest in understanding the advantages of this system?

If you really want to understand the system, seek out someone who has intimate knowledge of the physics of this system and all its parts.

If you are just contrary curious, keep on stirring the pot.

This new A/c system claim to save energy by as much as 40% , and this just pops out from somewhere suddenly, I have not read about it any where. This is a significant improvement. I am sure many are like me, are very curious to know how it works. I thought you have something more substantial to say.

As I said earlier, everything here is speculation.

I think that the resident experts (that does not include me) have given you their opinions. You have not seen fit to accept any of them.

If you have not read about it anywhere, that could be a clue.

Confront someone who sells them.

my question was very specific, on a well known engineering principle. You did not follow those links and replies before you shoot off. All those does not answer my specific question. If you have found the answer, please post it. If not, I am hoping others will be able to give the answer.

No answer you get here will satisfy you. You've proven that already.

Go challenge the people who made the claims: www.fafcosolar.com/go-solar/hybrid-solar-air-conditioning/how-hybrid-solar-air-conditioning-works/ maybe they will play your silly game.

<unsubscribes>

I had intended it to be a serious question and hope to get good answer. Your off topic comments and my unavoidal resultant replies do not add value to current subject matter. So stop blaming people for playing silly game!

I think it is hybrid with both Electrolux and compression system together . Like hybrid car.When solar is available use heat and produce refrigeration.Ammonia cycle. When solar is not available use electricity to run the Compressor.

My apologies.

I should have stayed out of this one altogether.

I added nothing to the thread.

I usually respect your contributions, but I'm disappointed in you this time! I get the impression that you, like most of the other responders here, are replying without having looked at the original link, which I'm convinced is a SCAM! If you can explain how adding more heat and pressure AFTER the compressor can make the system more efficient, please do!

Otherwise, follow the sage old advice: if you can't say something good, then don't say anything.

I don't think it is a scam. I forgot to mention manufacturers in China are already manufacturing them by the thousands. Go alibaba.com, and search for it.

It is neither scam nor it pops out from somewhere. The latest news is about the commercialization of 100% solar ductable central Air conditioning using solar thermal system and solar chiller. They claims that it can cool without the use of harmful refrigerants and also give hot water, and gives a reduction of 99% electrical energy use.

Link(s) please.

different technology, absorption not vapor compression.

Then what is the compressor doing in the description?

Hi Tornado,

I have outlined the operation of this cycle in previous answers, replying to the comment of ducted and chiller versions.

Major power consumption in Ac system is compressor. Any technology to reduce the power required to operate it will save energy. Compressor is the heart of the system. Working fluid is compressed to the required pressure and temperature so that it can give off the heat absorbed from refrigeration system and mechanical equivalent of heat in compressor. In the hybrid technology it appears that they have included solar panel to reduce the energy required by compressor .Solar energy is used to exchange heat as a heat exchanger to raise the temperature and pressure and thereby reducing the work required to be done per ton of refrigeration. The company who are manufacturing this unit can give better explanation.

hi Bravo,

It appears to take advantage of the solar heat providing the additional energy used to drive the pressure and temperature of the refrigerant higher than what a typical vapor compression cycle would operate at, this appears to make the condenser more efficient because of the greater temperature difference between the air and refrigerant providing a greater amount of sub-cooled refrigerant (cooled below its saturated condensing temperature) which enables more liquid refrigerant to enter the evaporator after the expansion device(some liquid will flash or expand during the lower pressure change, this appears to provide sub cooling by raising the temperature of the refrigerant with the energy from the sun. therefore the evaporator operates efficiently due to available liquid % is greater allowing more heat to be absorbed by the refrigerant liquid evaporating.

The smaller the difference between input temperature of warm air and output temperature of the chilled air at the chiller fan, the higher the efficiency of the system.

the co-efficient of performance or COP of a conventional system is based on the compressor power input, not solar heat input

Although heat energy is added, but this energy is not converted into work to compress the refrigerant, you need compression to bring about phase change where Hugh amount of heat is given off as the refrigerant condense. Purely adding heat as the case here merely increase pressure without causing phase change, no phase change , no heat pumping action . This is the basic physics of compression cooling. Many commentators seems to miss this key point.

The fact is the compressor requires greater lift and therefore more power input, you do not need compression for a phase change, it merely facilitates a change at a higher temperature. The efficiency would be better increased with a more efficient condenser rather than raising the temperature of the R410a higher, this system is exceeding the refrigerants critical temperature and borderline critical pressure, the only true solar air conditioner is the absorption cycle spoken of, which does not compress any thing.

To Understand the working of this hybrid system, one must return to the basic thermodynamic principle behind the process governing the cooling phenomenon in the air conditioning equipment.

Normally, we use the reverse Rankine Cycle in a Heat pump (Air conditioning...).

By adding heat from the Solar panel, we move the cycle higher up in condenser pressure. Also, the temperature of the condenser is higher. We need, then, to cool the condenser using the ambient air. Therefore, since heat addition and heat removal are both free, if the final result is more liquefied gas from the condenser, then we have increased the amount of cooling available. The electric power used by the compressor being the same as before (without the solar panel), means that we increased the efficiency of the system (at the expense of the ambient air and the sun).

Of course, the system must be tuned. The Condenser will need to be bigger to increase the cooling capacity, for example.

The whole system will be bulkier than normal and more suitable for large size cooling bigger spaces than just a room in a house. Also the cost will be less per kW cooling for bigger units (solar panel etc).

I have the feeling that your explanation is on the right track, probably some mathematics would make it more conclusive. Thanks for your input.

You've given me a glimmer of hope (hope that I'm wrong about it being a scam). But doesn't the compressor have to work harder to pump the vapor to a higher pressure? And, if there is more liquid evaporating in the evaporator, then the volume of material pumped will be greater, increasing the load on the compressor even further.

You have a point here about the compressor having to work harder for a higher pressure. But I do not think that it will be working harder because the cooling of the condenser is happening more efficiently due to the higher deferential with the ambient temperature, meaning that more heat is removed: NOW if the heat removed is more than the combined heat input from compression and solar, we will have more condensation (in gas mass) for the same amount of gas pumped. The whole system will balance out, having pushed the working cycle higher.

I did not do the mathematics, it has been a long time since I did not do such. You need to go in detail for the particular refrigerant type and have the Pressure Enthalpy chart...

I am sure that the hybrid system is not new as an idea or as a study. Making it work on an industrial scale is probably new since a lot of control can be better achieved with electronics nowadays.

Volumes: since the volume pumped through is dependent on the compressor, it remains the same. The mass of gas will be almost the same if the return temperature at the compressor suction inlet does not change significantly.

Bravo,

After seeing all the nay saying below and being skeptical myself, I searched a little and found this:

Made By Toshiba......

THIS IS AN AWESOME PRODUCT, SAVE 40% MORE OF ENERGY COSTS & GREENHOUSE GAS EMMISSIONS THAN A CONVENTIONAL SPLIT SYSTEM These are 3.5kW, 5 kW & 7.2kW Solar Hybrid Air Conditioner Split Systems which utilises a solar heating panel generating savings of up to 40% of the power cost compared to a conventional split system air conditioner/heater.They are ideal for areas up to 100m2 (or more if your home is energy efficient). As there is no other product like it on the Australian Market and there is no existing category for a solar hybrid, its performance (star rating) has been assessed on the split system only without the added advantage of the solar panel. Not only do you achieve great savings on power bills but you enjoy greater performance with rapid temperature response and super quiet running. Simply, its cleaner, cheaper and better.

THE BENEFITS

Around 40% more efficient & cheaper to run than traditional comparitive split system - less on your power bills!
Highest Performance Rating Available in Australia
Cooling Old 6.5 Star New Rating 2.5 Star | Heating Old 5.5 Star New Rating 2.5 Star
Super Quiet
Quicker temperature response
Friendly to our precious environment
Easy to use remote control
Easy to install
5 year warranty

HOW IT WORKS

Working principle of Solar Inverter Air Conditioner

The Solar Air Conditioner system is a system that utilizes the sun as a heat source to assist the energy needed to drive the cooling process of a typical air conditioning system which in turn reduces the electrical consumption required to run the Toshiba DC Inverter Compressor.

The Solar Air Conditioner system is similar to a regular air conditioner in that the refrigeration takes place by evaporating liquid with a very low boiling point. In both cases, when a liquid evaporates or boils, it takes some heat away with it, and can continue to do so, either until the liquid is all boiled, or until everything has become so cold that the sub-zero boiling point has been reached.
The difference between the two is how the gas is changed back into a liquid so that it may be used again. A regular air conditioning system uses a compressor to increase the pressure on the gas, forcing it to become a liquid again through the use of a condenser coil. The change of state of the refrigerant starts to take place approximately 2/3rd's of the way down the condenser. The Solar Air Conditioning system uses a different method. It uses the solar heat from the sun to superheat the refrigerant which enables the refrigerant to begin changing state at the top 2/3rd's of the condenser coil. By using this method it reduces the superheat of the compression required to achieve the cooling process in the conventional cooling system as well as utilizing more of the condenser cooling face to the coil. The conventional air conditioning system is only able to change a portion of the gas into a liquid state so as when the refrigerant enters into the system it is a saturated vapor. The Solar Air Conditioning process allows more of the refrigerant to change state back into liquid faster as well as allowing the transformation of more liquid into the system.
In summary the Solar Air Conditioner utilizes solar power thus saving approximately 37.5%-67.5% of electricity consumption that is consumed by a regular air conditioner, it has an awesome operating temp range of -8 degrees C to 55 degrees C, contact us today for a free installation quote.

ENERGY SAVINGS

this place isnt for ads and sales pitches

I don't believe their explanation, either. Something else must be going on.

The compression process in hybrid solar air- conditioner is completed partly by compressor and remaining ,by adding solar heat before starting of condensation process. The condensation process will start only when the refrigerant gas temperature is higher than the ambient temperature .it is achieved by adding solar heat.

Heat added during compression (by compressor) and added by solar collector is taken out at condensation stage . exactly as happens in normal ai-rconditioner

Instead of vacuum tubes , they used 10mm copper pipes enclosed in a black insulated tempered glass installed between the low pressure pipe of the indoor unit to the outdoor unit

http://ph.california-electronics.com ps check this out for the detailed explanation

That's not a detailed explanation. It's a sales pitch. And the use of the name "California Electronics" for a Philippine company is totally misleading.

If I read correctly, this one places the solar collector on the low-pressure side of the compressor, while the original link indicated it was on the high pressure side... Still sounds fishy to me.

It certainly look and sound fishy, but it is not possible so many manufacturers got fooled and already manufacturing and selling them !!

Best advice I can give you...buy one and take it to a university for analysis. You might get some donors to invest in the research, or the campus might just pay for it to give the engineering students an assignment.

I have not read the websites linked but from what everyone says due to all the misleading or missing information getting the facts from the machine might be your only option.

Drew K

Given the fact that to feed an airco system, you need energy.

This energy is mostly derived out of the compressor (and supplied out of the net or grid).

Knowing that a good black heat exchanger panel can convert sunlight into heat and that this ratio can be 1000 Watts/m2 it is just bringing this in the system and letting the compressor use less energy.

We are used to our classic, read historic piston compressors as used in A/C units and refrigerators. (scroll is only being noticed)

When using inverter driven compressors, they can have a process controlled speed/power feed (with feedback) or even parameter(s) controlled intelligence.

How does it fit?

In the suction side of the compressor. There is room for enthalpy play. Heating up the lines after the medium has done its work to cool will create considerable gain, especially when the evaporation valve is part of the process points.

Further a grid tie PV panel can also contribute to the power, used by the compressor.

These systems are on the market for more than 4 years. It is just math, no hocus pocus. They can work in different configurations as long as they have enough intelligent controls. (yes even in the pressure side)

Aren't we used to our good old things? How much solar is really used? It is just a matter of price and time. Fire works were China's invention too.

I will not say for sure how it works as I'm not. I can give you some observations and experience that may point you in the right direction. This is based on a standard vapour compression cycle, using mechanical compression in an AC application.

-In days gone past, one way that you could increase capacity of a system was to boost the head pressure (condenser pressure). This would increase the differential pressure of the inlet and outlet of the thermal expansion valve. Sporlan has good charts that shows this. This was harder on the compressors and cost more to run.

-A condenser with a dedicated sub cooler, or a refrigerated sub-cooler on the liquid line that feed the metering device would prevent flash gas at the expansion valve, saving energy.

-with the advent of balanced port TX valves, the pressure differential is no longer as important. Electronic TX valves are more accurate and controllable. This now allows for lower head pressures, thus less load on the compressor and less energy use.

-today it is all about energy. To date the manufactures have done their best to take the load off of the compressors. Different refrigerants with better specific heat and that allow better compression ratios. The use of oversized condensers for better heat rejection and reduce condenser pressures. Different compressors. You will find a multi-pack of several scroll compressors in place of one reciprocating one. Changes to the scroll compressor. Copeland now has what they call a digital compressor. It saves energy by an internal capacity control. The use of DC drive compressors is a major step as they can be variably controlled

The big one: Controls, controls, controls.

I think this is an R-410a (ozone safe) refrigerant, according to the web site in the FAQ section. This means it is intrinsically a VCC refrigerated air system. The big HUGE difference is that instead of attempting heat transfer in the condensing coils at 170 degrees Fahrenheit, the solar collector is heating the compressed refrigerant to near 350 degrees Fahrenheit (limited by pinch temperature in the heat exhanger at the solar collector between the organic heat transfer fluid and the refrigerant).

The claim being made is that the process of cooling in the condenser for this now super-heated refrigerant is much more efficient (Newton's law of cooling) in that the higher the temperature difference, the more rapid the cooling. The result (given the claim), is that liquid is being made higher up in the condenser (instead of the final 1/3). Hence, by the time the refrigerant leaves the condenser toward the expansion valve, it is nearly 100% liquid, resulting in lower expanded vapor temperatures.

This process certainly appears to be "counter-intuitive" at first glance. It does seem odd that by starting off at a higher temperature (thus containing more heat), a higher state of condensation is the ultimate result, especially since nothing was implied about increasing the surface area of the condenser, and nothing was mentioned about the operating point of the compressor as far as pressure.

this is all true ,

however the laws of thermodynamics are fixed, the amount of refrigerant sub-cooling is a result of the ambient temperature, the heat ex-changer temperature and pressure,

additional super-heat at the discharge of the compressor? (maybe around 1kj/kg from this vacuum tube collector places possibly an additional 30-40% of heat required to be rejected by this small air conditioner) the only way the heat ex-changer could perform more efficiently is a greater temperature difference, between the working fluid and the surrounding air. the only way adding heat at the compressor discharge will change the dynamics of this system and to possibly increase its performance is by also raising the condensing temperature.

plotting this cycle on a pressure enthalpy chart with discharge super-heat only, simply adds heat to the condenser, no cycle change would occur, in fact it would be less efficient.

The answer is contained in the statement that a higher pressure differential at the expansion valve will produce a sharper change in temperature... I see here that if the refrigerant return temperature at the compressor is lower (as a result of more liquid being sent to the expansion valve for a given refrigeration load), then the compressor can (without changing electrical load) produce more pressure at its output. If then we are speaking of a system with a higher compression, perhaps nearly saturated liquid at the output of the compressor, then superheating by solar input may indeed provide a better operating point in the condenser. Otherwise, this will be nonsense, as simply adding sensible heat to the system designed to remove heat is an oxymoron.

The statement has been written to

1) sell the product

2)confuse the opposition

3)mask its true cycle

greater sub-cooling and a higher liquid percentage entering the evaporator will produce a higher evaporating temperature, not lower, typically an air conditioners evaporating temperature will be above freezing to prevent ice formation and prevent too much moisture removal.

The sales statement is basically incorrect,

the greater differential pressure will meter more refrigerant thru an orifice, cause a rise in compressor power requirements, and a reduced volumetric efficiency at the compressor, .... the debate is about how much extra electrical energy is actually required when adding heat via the vacuum tube collector.

the clue is the refrigerant condensing at the top 1/3, I am assuming this is a trans-critical cycle and is operating an elevated pressure and temperature on the condensing side of the system, they are concealing the elevated pressure because R410a 's critical point is at times is most likely exceeded.

most R410a air conditioners will exceed the critical temperature at the discharge of the compressor at given times, however by not exceeding the critical pressure, they do not exceed the critic point.

Raising refrigerant above the critical point will cause deteriation of the refrigerant, non condensibles, etc.,

super heating the refrigerant at the discharge does not shift the condensers efficiency, merely place greater load on it.

Pressure is the answer,

In the absence of solar energy,will the same compressor still be okay with refrigerant R-410a?

I just looked at their website.......It's all BS and wouldn't work on solar power for 2 seconds it isn't ammonia, it's R22 and uses "famous" compressors that consume 230V what a waste of time

So from what I have read, this website is a scam...but the concept is possible or has been done in another form. So, what would work?

Last year I was looking at an amonia refridgerator and considering how I could power it with vacuum solar tubes. I spoke with another Engineer who told me his Thermo professor talked about using the exhaust manifold to power one of them to cool a car, but the problem was it would need a heat sink approximately the size of the underside of the car.

I know some car air conditioners are 2 or 3 ton units so would using solar be a viable option when cooling a house, you could use a small cooling tower to cool the thing if you had to.

Drew K

Absorption refrigeration, either ammonia in water or water in lithium bromide, can work. I think ammonia requires a higher temperature than simple passive solar can give, and borderline with evacuated tubes. Concentrated solar (focused lenses or mirrors) gives enough temperature.

fire up the Fresnel!

What temp does ammonia require? I saw a very simple vacuum tube system that was putting out almost 100°C in November (northern latitudes).

I think by pressurizing the system and using a better designed solar collector significantly higher temperatures could be achieved.

Drew K

absorption systems can be designed to operate with a heat input as low a temperature as 80 degrees centagrade, or upwards. they can include multiple stages or effects. in recent years the triple effect machine has been perfected, the higher temperatures and number of stages will improve the efficiency or COP. There are numerous sites around the world that have absorption solar cooling systems that work, mostly LiBr/H2o pairs due to their more efficient operation, there is another version called adsorption chiller, which uses a dessicant in place of the solution (liBr or NH3), and a better option for a smaller system can be a ground loop, not a cooling tower.

This is the future, the problem is economic factors.

Do you have any links to research papers or manufacturers?

Drew K

This can't be a scam, go to Alibaba.com or made-in- china.com, there are already many manufacturers .

Nothing much technical in it as it sounds. The air conditioner compressor's job is to raise the temperature of a refrigerant fluid. Solar energy can be used to provide a portion of this temperature increase. This way it can reduce the compressor's workload and help it to consume less electricity. Simple.

"The air conditioner compressor's job is to raise the temperature of a refrigerant fluid."

NO! The compressor's job is to increase the pressure, so that once the heat is removed, it will condense to a liquid. If it were possible to compress the gas without causing it to get hotter, that would be done. All heat added by compression (and any other processes) must be removed if the gas is to condense to a liquid. It is the evaporation of that liquid that does the cooling of the house or other volume.

Abdenour Bouraba, Mohamed Saighi, Hind Saidani-Scott, Abderrahmane Hamidat, Cooling mechanism of a solar assisted air conditioner: An investigation based onpressure–enthalpy chart, International Journal of Refrigeration 80 (2017), pp. 274-291.