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Solakool air-conditioning

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Started 8 months ago by peuckers
Latest reply from photonthief

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peuckers
Member

Has anybody had any experience with/know anything about "Solakool" solar thermal (solar hybrid) air-conditioners?

http://www.solakool.com.au/
http://www.greencircle.net.au/

I happened to see one at the home show. Basically there's a solar thermal panel that 'collects heat' during the day to reduce power costs. I'd pretty much decided to get a split system installed for this summer but this loos promising.

Background:

I'm looking to cool the NW bedroom of a Victorian weatherboard house - I have bulk insulation in walls/ceiling, low-e Glass in windows, plus thermilate-laced paint on the outside & a deciduous tree outside North-facing windows, but it still gets too warm in summer. We currently use a portable aircon on hot days but this takes about 4 hours to cool the room & is very noisy (can't sleep with it on).

Posted Friday 23 Sep 2011 @ 12:04:37 am from IP #
Samo
Member

Looks like commercialisation of the ejector jet cooling that ANU was working on. They used heat to help pressurise the gas, so that you only need a very small compressor.

Posted Friday 23 Sep 2011 @ 9:20:26 pm from IP #
fireflies
Member

The technology absolutely sounds like the way to go for A/C. I was however struggling to understand the concept. Still not sure how adding temperature to the coolant makes compression easier but the link below seemed to have the most detail explaining the process. I think it has to do with an efficiency gain in compressing then condensing refrigerant when the compression is done on warmer refrigerant but, really, I can''t wrap my head around it. Anyone have an understanding of these things and care to comment?

http://www.rightsolarairconditioning.com.au/SolarAirconditioner_HowDoesItWork.html

Posted Saturday 24 Sep 2011 @ 4:32:48 am from IP #
Samo
Member

Here's a link to some info on ejector jet cooling, which I think is most probably the technology behind these units:

http://solar-thermal.anu.edu.au/low-temperature/solar-cooling-using-ejectors/

Posted Saturday 24 Sep 2011 @ 9:56:16 pm from IP #
sun2steam
Member

Ejector jet cooling is certainly an interesting technology even if there are still quite a few obstacles on the way.

However there is most certainly nothing of that kind in the Solacool.
The technical description of the Solacool is just gibberish. Both the flow chart and the description don't make any sense in regard of their specific process. Either they want to hide what they are actually doing or they don't know what they are doing.

We have had this discussion before in this forum but I cannot find the thread. Maybe one of the former contributors can help out.

Posted Saturday 24 Sep 2011 @ 10:26:39 pm from IP #
peuckers
Member

Just got a more detailed document from the agent in Vic (srry for long post)

"GreenCircle- SolaKool

Summary of Operation:
In a GreenCircle-SOLAKOOL Solar Air Conditioning System light is used as an energy to reduce the operating time of the compressor of a typical air conditioning system which in turn reduces the electrical energy consumed.
The GreenCircle-SOLAKOOL Solar Air Conditioning System is similar to a standard a/c 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 absorbs energy in the form of heat 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 can be used again. A standard air conditioning system uses a compressor to increase the pressure on the gas, so that when it enters the condenser coil the combination of pressure and cooling from ambient air condenses it into a liquid in the coil. The change of state of the refrigerant starts to take place approximately 2/3rds of the way down the condenser.
The GreenCircle-SOLAKOOL Solar Air Conditioning System improves on this basic method by using the heat from the sun to add thermal energy to the refrigerant vapour which increases the difference in temperature between the refrigerant and the ambient air hastening condensation. It also increases the refrigerant pressure by expansion which all means that the refrigerant now begins changing state in the top 2/3rds of the condenser coil.
By using this method it reduces the superheat of compression required to achieve the cooling process in the conventional cooling system as well as utilizing more of the cooling face of the condenser coil.
The conventional cooling system is only able to change a portion of the gas into a liquid state so that as it enters the metering device, or capillary, it is a saturated vapor.
The GreenCircle-SOLAKOOL Solar Air Conditioning process allows more of the refrigerant to change state back into a liquid faster as well as allowing the transformation of more liquid into the metering device.
In our solar ac system the low pressure, low temperature refrigerant is compressed before gaining solar thermal energy in the heat exchanger of the solar absorption panel so that we now have both higher pressure and higher temperature vapour.
Then the vapour is condensed into high pressure liquid at ambient temperature by passing through the condenser.
The high pressure liquid is converted into low pressure, low temperature vapour at room temperature when it passes through the capillary before entering the fan head.
This is achieved by throttling and decompression of the liquid into vapour at low pressure and low temperature in the capillary.
This phase change absorbs energy out of the room in the evaporator inside the fan head.
Air is blown through the condenser to distribute the cooling throughout the room.
Moisture forms on the surface of the evaporator coil where it is piped away to the nearest storm water drain.
In the heating cycle the condenser and evaporator are reversed in sequence so that heat energy is released in the fan head instead of outside."

I'll try to get this plus the rest of the doco uploaded on their website.

Posted Wednesday 28 Sep 2011 @ 4:04:48 am from IP #
sun2steam
Member

I don't get it. If you heat up the compressed vapour to do whatever they claim, there is also more energy required to pump the gas to this pressure using the compressor.

The only option I can see is to operate in steps.
1) compress gas
2) stop compressor and apply heat to increase gas pressure
3) after a while, when pressure drops by condensing the gas, start 1) again.

But the text is technical gibberish and does not mention a step wise process.

Posted Wednesday 28 Sep 2011 @ 5:01:38 am from IP #
fireflies
Member

"The GreenCircle-SOLAKOOL Solar Air Conditioning System improves on this basic method by using the heat from the sun to add thermal energy to the refrigerant vapour which increases the difference in temperature between the refrigerant and the ambient air hastening condensation."

I'm hastening toward S2Ss position on this one. Disregarding all the rest of the blurb which pertains to any condenser based refrigerating system - the 2 paragraphs in the middle of the spiel imply that adding heat to a cooled refrigerant increases the temperature difference between ambient air and refrigerant. It doesnt make sense to relate ambient air temp to an increase in condensation. It is the environment within the condenser that is critical - ie its pressure and temperature. And how does heating refrigerant increase condensation?

"It also increases the refrigerant pressure by expansion which all means that the refrigerant now begins changing state in the top 2/3rds of the condenser coil."

By expanding the volume you decrease the pressure, not increase the pressure - basic physics.

"By using this method it reduces the superheat of compression required to achieve the cooling process in the conventional cooling system as well as utilizing more of the cooling face of the condenser coil."

Reduces the superheat of compression required to cool the refrigerant. Adding heat cools the system???

"In our solar ac system the low pressure, low temperature refrigerant is compressed before gaining solar thermal energy in the heat exchanger of the solar absorption panel so that we now have both higher pressure and higher temperature vapour.
Then the vapour is condensed into high pressure liquid at ambient temperature by passing through the condenser."

Perhaps there is something in this part of the explanation that goes to what is happening but it skates over the process to such an extent that we end up with not an understanding of the process but a sense that it is ; A. bogus or B. not understood by the Solakool people. C. deliberately misleading so as to protect intellectual property.

We cannot dispute independently corroborated efficiency testing of the units but the explanation of process that they give only leads to suspicion that they're selling snake oil refrigerant (SN8K 710).

Posted Wednesday 28 Sep 2011 @ 5:15:55 am from IP #
dbindoff
Member

Since their stated coefficient of performance is less than that currently available from the best air source inverter heat pumps on both cooling and heating cycle, it does not make sense to go to the trouble and expense of installing a thermal collector.
In the future I am looking forward to adsorption coolers utilising 'waste heat' from solar HWS and on a domestic scale. I found this link but its very 'commercial' scale.

http://www.weatherite-manufacturing.com/edit/files/brochures/ADsorption%20chiller%20brochure.pdf

I know there are better ones I've seen in the past. There was a smaller scale supplier in Australia also I think. They were developing a residential size unit in Netherlands, not sure where that's got to.

Posted Wednesday 28 Sep 2011 @ 5:35:20 am from IP #
sun2steam
Member

I agree adsorption heat pumps appear to work very efficiently, but they are hard to find.

I have just filed a patent application for a solar domestic adsorption cooler (+heater) with integrated heat storage. I would like to join up with somebody who has experience in building air conditions to manufacture these systems.

Sorry about the hijacking. I should have started my own thread. But it was too tempting.

Posted Wednesday 28 Sep 2011 @ 6:17:20 am from IP #
dbindoff
Member

very interesting (and exciting), I wish you every success! Do you mind me asking what the heat storage medium is?

It seems to me it's a 'must have' technology for Australia, so I hope it can be developed here.

Posted Wednesday 28 Sep 2011 @ 7:17:32 am from IP #
fireflies
Member

S2S Good luck with development of your concept to the commercial stage. Can I place an order for one a/c now?

Posted Wednesday 28 Sep 2011 @ 9:27:12 am from IP #
sun2steam
Member

Thanks guys. The heat storage is based on erythritol, a sugar alcohol with a melting point of about 120 C and a very high heat of fusion. If the sugar melts It can store about 4 times the heat energy that could be stored in the same volume of water.

The system will eventually look similar to the systems in figure 3, 4 and 5 of this paper: http://engineering.ucsb.edu/~yuen/references/rer-8.pdf

Posted Wednesday 28 Sep 2011 @ 10:13:25 am from IP #
karmacoma
Member

This is an interesting thread about potentially useful new products. But hang on a bit. Before skating off on a tangent, let's deal with the merits of Solakool, part of which is clarifying how it works. Seems to be a problem here, of the sort that says adding heat to steam will help it turn back into water. The vendor's explanation is not clear, and that raises the spectre of faulty logic. Maybe the vendor will help us out here (concern is being raised about your product, you need to comment), or maybe someone who is keen on refrigeration engineering can interpret. Now that S2S has declared his interest, potentially as a competitor, further input is needed.

Perhaps discuss the erythritol system in a separate thread, let's deal with Solakool here.

Posted Wednesday 28 Sep 2011 @ 12:23:37 pm from IP #
Glen Gardiner
Member

Hi there, I looked at solar air conditioning a while a go. I have always been interested in ways that I can reduce my power consumption. Solar air conditioning seemed to be a logical progression from standard air conditioning.

I started looking about 1 1/2 years a go at the alternatives. I found that there were a few suppliers out there but pretty quickly settled on the one that I thought had the substance behind them and would be there long enough to warrant their product. An engineer their answered all of my questions and the company had substance behind them. I found them really easy to deal with and very knowledable. They also sell in a few other countries overseas. They told me that their manufacturer is the original patent owner, has a research and development team and an internationally recognised quality assurance program.

When I was investigating what was out there, I came across Solakool also and had the same problems that have been expressed, ie understanding how the system worked etc. A few of my friends also were looking at what they should buy for air conditioning and when I steered them towards Solakool they also had the same problems that I had.

When I was corresponding with Solakool on the purchase of the systems I wanted, they were happy to answer all my questions pretty promptly, until I started to question the detail. When I did that, they stopped corresponding. As a result of their lack of depth, I kept looking for an alternative.

I found ICE Solair and spoke to the Engineer there and it all made sense. He was able to explain the process so easily. To put it simply, it works on the basic principle that if you heat a gas and it can't expand, then it will pressurise. The way the ICE Solair system is set up, it has a non return valve along the line coming from the indoor head unit to the collector before it gets to the outdoor unit. So when the gas is heated, it can only go in one direction, straight in to the compressor. So the amount of work that the compressor has to do is reduced under full load and eventually when the outdoor unit cycles off it will stay off for a lot longer than an inverter system because the collector keeps pressurising the refrigerant. Seems logical to me.

If you need to get in contact with ICE Solair, just visit their web site http://www.icesolair.com and get in contact with them. I am sure they will help you as much as they helped me. I ended up buying a system from them and I have been really happy with it. It is really quiet and consumes bugger all:-)

Glen

Posted Friday 7 Oct 2011 @ 2:12:45 pm from IP #
dbindoff
Member

The ICE Solair looks fine, but the coefficient of performance does not seem to be markedly above many inverters currently available (around 4) I did not look exhaustively and the others may be smaller capacity but if I went to the trouble of installing a separate collector I would be looking for a little more upside in the performance, it's a great idea which I would like to succeed.

Posted Saturday 8 Oct 2011 @ 5:51:49 am from IP #
Glen Gardiner
Member

Thanks for your points dbindoff. I wanted to understand myself so I called ICE Solair to have a chat about it. This is what they explained to me:
1) The energy efficiency ratio (eer) and coefficient of performance (cop) are ratios of performance where the system is under full load. Whether it is an inverter system or a solar air conditioning system, it doesn't fairly represent how the system is designed to work.
2) The tests completed to get those results do not look at how the system uses power over a long period of time. No manufactures have completed tests to show this. They all just calculate it based on the rated power output and take in to account how it is designed to operate. They probably don't do this because I am sure it would cost a lot and they are not required to do it by law....
3) The annual energy efficiency ratio (aeer) and annual coefficient of performance (acop) has only just come in to force this year and takes in to account standby consumption. It does not take in to account how either an inverter or solar air conditioning system is designed to work.
4) Because the eer and cop are only related to full load and not performance over time, comparing one system against another based solely on this is not fair. You have to look at how they operate. Under full load, the performance of any system is like a fixed speed compressor system under full load. An inverter system is approximately 70% more efficient in running than a fixed speed one and so to work out what the average consumption would be, it would be about 70% of its rated peak consumption. An ICE Solair solar air conditioner is 30-50% better than an inverter system. So the system will on average consume approximately 50% of its peak rated power output or less (ie peak x (70%x 70%)). So you are much better off running with a solar air conditioner.

Some other things that they said I found interesting also was:
5) An inverter system is designed to achieve the set temperature and then ramp down to approximately 70% of its rated power draw. Its power draw then just bounces up and down a little as required to keep the room at the set temperature hovering around the 70% point - ie operating say between 65-75% of it rated power draw to keep operating the system.
6) The ICE Solair solar air conditioner is designed to be 30-50% more efficient than an inverter system. The way it does this is by heating the refrigerant and following the process I previously detailed.
7) To achieve the 30-50% energy savings, the system has to be sized correctly for the room that it is in. Once the outdoor unit can ramp down, that is where the real energy savings are achieved. The hotter it is, the more energy (by way of heat/pressure) is put in to the refrigerant and so the outdoor unit will stay off for a lot longer because the refrigerant keeps getting a little bit more pressure in it every time is passes through the collector.
Because the ICE Solair solar air conditioner uses a fixed speed compressor, it is able to remove the moisture faster from the air then an inverter system. They said that in their experience, a lot of people north of Gladstone latitude tend to have a lot of problems with inverter systems trying to get the moisture out of the air. So they tend to get fixed speed compressors to avoid this issue.

Hope this is of help. If you have any questions, I am sure that someone at ICE Solair would be happy to answer any of your questions related to solar air conditioning. You can get in contact with them via their web site http://www.icesolair.com

Glen

Posted Thursday 13 Oct 2011 @ 4:46:27 am from IP #
dbindoff
Member

Thank you for your detailed 'research' Glen. If those 'actual cycle' savings are similar for the heating cycle it would be of interest if my inverter packs it in. (in Hobart we are predominantly running heating)

Posted Thursday 13 Oct 2011 @ 5:43:48 am from IP #
Glen Gardiner
Member

Becasue the system is designed to capture the ambient temperature and heat the refrigerant, I would imagine they would have designed the collector to be large enough to capture enough heat to still do ok in Tassy. Would be a good one for you to make contact with them on it.

Glen

Posted Friday 14 Oct 2011 @ 5:13:59 am from IP #
sun2steam
Member

Has anybody understood any explanation? I don't.

Posted Friday 14 Oct 2011 @ 7:58:32 am from IP #
fireflies
Member

Taking the given explanation by GGardiner, that heating the refrigerant after passage through the unit increases its pressure and hence decreases compressor effort as a true function, I can only see it functioning in the following situation:
- A non-return valve and an extra compressor/pump is incorporated between the low pressure feed line and the 'solar heating panel'. This would move the coolant in a forward flow direction. Without that, the low pressure line would get back pressure from the applied heat and stop functioning. That this is not mentioned in the blurb only adds more questions as to what is the technology being applied.
- In addition the question comes up, if a heat source is being gained from the sun to pressurise the refrigerant, is it not also beneficial for the heat from the condenser to be utilised, and if not, why wouldnt it be.
- And finally, and critically; does pressurizing a refrigerant with heat, enable the main pump/compressor to work more effectively to add even more pressure, and with condensation, produce the low temperature condensed refrigerant.

To me, if those questions were adequately addressed then the science could be somewhat accepted. Without those details it does come across as a bit confusing.

Posted Friday 14 Oct 2011 @ 2:59:38 pm from IP #
photonthief
Member

It sure would be nice to know which company makes the Solakool units, and see what the manufacturer website has to say.

Sure. The Solakool units are made by Jiangsu Chuanglan Solar Air Conditioner Ltd, in China, and I suggest you go to their website. Some of the key points are :-

The 'How it Works' operational flow diagram on the Solakool website is a slightly tarted up reproduction of the same diagram on the manufacturer website. You probably noticed that the English on the Solakool diagram is a bit dodgy, which is because the writing is copied directly from the Chinese manufacturer website. The original diagram shows an evacuated tube thermal collector - more about that later.

Here is the 'Official Manufacturer' text that accompanies the operating diagram :-

------------------------------------------------------------------------------
Why Hybrid solar air-conditioner can save electricity?
Here are the reasons:
Firstly, it absorbs solar energy to heat the inside medium by using a solar collector. Freon from the compressor goes through the copper coil inside the collector and undertakes a heat exchange. Freon exchange heat with the medium inside the solar collector then go through a cycle inside the system for cooling and heating.

Secondly, it adopts a highly efficient heat-exchange system. The use of the internal thread pipe, hydrophilic aluminum fin and the optimal heat exchange system reduce energy loss, improve the overall efficiency and effectively ensure the performance. Therefore, hybrid solar air conditioner is more convenient and energy-saving than regular air conditioner.

Comparing to Current Products
1. Conventional air conditioner consumes too much, users have to pay a heavy electricity bill.
2. Photovoltaic (PV) system costs a large amount of money to build up.
3. Thermally driven absorption cooling is also very costly, and its cooling capacity is not big enough.

Performance Characteristics
High efficiently,energy-saving,comfortable and money saving,exceeding national first grade energy standard.
Durable and long-lived,smooth running.Low-loaded operation of the compressor to extend its duration.
Healthy and comfortable,constant temperature and keeping air conditioner disease away.
It is not frequency conversion air conditioner but superior to it because conversion type begins to save energy when the indoor temperature reaches the set value,while the hybrid solar air-conditioner runs in the optimal state immediately after starting and it achieves the sanme effects of traditional air conditioner with less power consumption.
Super luxurious appearance decorates your home.Indoor panel adopts aluminum alloy and wire drawing metal color board to make your house more sparkling.
Automatic open and close dustproof air outlet.
Easy installation,same as the traditional air conditioner.
With strong adaptability,Chuanglan hybrid solar air conditioner can run at super low and high temperature from -7℃ to 53℃.
Exceeding the national standards and applicable to all kinds of environment.
High Performance Japanese Brand Compressor (I believe it is Mitsubishi/Toshiba)
Durable and long-lived, smooth running. Low-loaded operation of the compressor to extend its duration.

Four-fold Heat Exchanger
As one of the main components of air conditioner, Chuanglan hybrid solar air conditioner adopts four-fold heat exchanger (take Supreme Silent as an example) heat exchanger effective area is increase by 20-40% than V-shape and flat heat exchangers, thus the cooling and heating effect are improved greatly.

High-quality Internal Thread Copper Pipe
Compared with normal copper pipe, the heat exchanging area of internal thread cooper pipe is significantly enlarged so does the exchange effect. Meanwhile, it can resist frosting and increase its starting ability at low temperature.
---------------------------------------------------------------------------

FWIW, the 3.5kW (cooling capacity) split unit can be bought from the factory for about US$500 each, in x10 quantity. The quality of the unit seems fine as far as it is possible to tell, and the EER specs are typical of non-solar-assisted units.

Full specs are on the manufacturer website (tho hard to find), and exactly match the part numbers and EER specs given on the Solakool website. However, one interesting point to note is that the standard configuration from the factory uses an evacuated tube heat collector, which can be physically attached to the front of the condenser unit. A cylindrical water-filled header tank sits atop the tubes, and the whole show looks bulky, cumbersome, and unaesthetic. In the notes at the bottom of the spec sheet is the sentence: 'Flat plate type solar collector available, which is easier for installation.' Apparently then, the specs refer to the standard system with their evacuated tube collector, not for the flat plate system sold here. As an evacuated tube collector is presumeably better, this would imply that the specs for the flat-plate Solakool unit are actually somewhat worse. Then again, maybe the exact collector (or even lack thereof) has little effect on the specs.

The manufacturer makes no claims (that I could find) re electricity savings. Solakool claim 'Save up to 80% in electricity charges', which is obviously absurd. On another webpage they claim savings of ~38%, based on comaprison with a 'Normal' aircon having an EER of 2.38 That is an equally absurd claim, for typical EER ratings for competing units range from ~3.0 to 5.7, depending on the brand, model and size of unit. Solarkool and the manufacturer both claim an EER of ~3.8, about the same as for non-solar-assisted units, so nothing that I have seen shows that the solar collector does anything useful.

The previous postings make reference to another brand known as Icesolair. I know exactly where those units come from as well, but will talk about that in the next posting, where I might also talk a bit about the 'theory' behind these 'solar assisted' units.

Posted Friday 20 Jan 2012 @ 5:29:10 am from IP #
fireflies
Member

photonthief it would be interesting to get your take on the 'how it works' for all the sales pitch solakool provide there seems to be no coherent explanation how heating the coolant, increases efficiency of the compression/ cooling cycle.

Posted Friday 20 Jan 2012 @ 12:20:49 pm from IP #
photonthief
Member

Fireflies, thanks for your feedback and I'll talk about the 'theory' shortly.

Firstly though, let's look at the competing Australian business, IceSolair. Their solar aircon units appear to be also made by Jiangsu Chuanglan Solar Air Conditioner Ltd. In other words, they are importers just like Solakool, and their units are in fact the same as those sold by Solakool. How do I know that? IceSolair sell three styles of unit, wall-mount, ceiling-cassette and slimline floor-mount. To their credit, IceSolair provide a full spec sheet for the models available in all of these styles, and these tables of specifications exactly match the specification tables on the Chuanglan website, except that the tables have been slightly modified to reflect the use of a flat-plate collector rather than the evacuated-tube collector that is standard. As noted in my previous post, in the notes at the bottom of the Chuanglan spec sheet is the sentence: 'Flat plate type solar collector available, which is easier for installation.' As with Solakool, IceSolair has opted for the more aesthetic and easier-to-intall flate-plate collector option. It seems clear that the IceSolair units and the Solakool units are the same, and both are made by Chuanglan.

However, the 'operation diagram' and description of operation on the Icesolair website is slightly different, with the solar collector being shown BEFORE the compressor, rather than after it. A likely explanation is that IceSolair felt a need to differentiate 'their' product from the Solakool product, and thus produced their own version of the diagram and operation. The IceSolair 'operation diagram' is very much a re-hashed version of the Chuanglan diagram. Even the Energy Label on their diagram is a re-hash of the Energy Label on the Chuanglan website, showing an EER of 3.72, pertaining to model TFK-32GW. If anyone really wants to know why the IceSolair operation diagram is different to that of the manufacturer, they would need to ask IceSolair. Personally I must give precedence to the information provided by Chuanglan, after all, they are the company that manufacture these units, not IceSolair, who are simply an importer.

What ultimately matters is the EER specs, and the manufacturer specs for the Chuanglan/Solakool/Icesolair units are very respectable at ~3.8, assuming we believe them. More precisely, the best inverter units seem to do slightly better in the smaller units, say up to ~3kW, see the thread entitled 'Split system inverter aircon efficiency'. However, The larger inverter split wall mounted units from Mistubishi, Daikin, Panasonic etc have woeful EERs in the range 3.0 to 3.5. My 7.2kW Mitsubish claims an EER of only 3.33, whereas the Chuanglan unit claims 3.82, not bad at all - if it is true, then I am jealous. It is a pity that the Australian Chuanglan importers felt a need to make absurd comparisons by claiming that a 'normal' airon has an EER of 2.38.

While I have my 'pro-Chuanglan' hat on, it is worth noting that the modern inverter units are VERY complex, packed full of electronics, much of it highly stressed such as the high-power inverter electronics that drives the brushless compressor motor. A high-quality hermetic-type 50Hz AC compressor such used by Chuanglan will almost certainly outlast a inverter-style compressor. If Glen is still reading, I have my doubts about whether the 'solar assist' provides any significant benefit, but the specs of your IceSolair unit are just fine regardless, and you may well have the last laugh when those of us with inverter units have the electronics fail.

I'm out of time, but may talk about the solar assist 'theory' later.

Posted Friday 20 Jan 2012 @ 10:54:26 pm from IP #
photonthief
Member

fireflies said:
photonthief it would be interesting to get your take on the 'how it works' for all the sales pitch solakool provide there seems to be no coherent explanation how heating the coolant, increases efficiency of the compression/ cooling cycle.

Agreed. All of the 'how it works' diagrams and explanations are pseudo-scientific gibberish.

One of the givaways that the whole thing is just nonsense is that there is no proper scientific or engineering reference to this method at all, and I have had a good look. EVERYTHING gets back to pseudo-scientific, gibberishy claims made by Chinese companies, with no independent test results, and no independent study or textbook reference to the theory. Solar refrigeration is certainly possible by many methods such as PV or absorption, but it is no coincidence that all of these other methods are proven, well understood, well documented, and commercialised by large companies within and outside of China. Could anyone seriously think that the large Japanese, American and European companies would not already be selling similar 'solar-aircon' systems if it actually worked?????

There is universal agreement that the 'solar collector' is an add-on to a standard compressor-type refrigeration/air-conditioning system, which is very well understood indeed. As the standard refrigeration cycle is so well understood, I am fairly confident about predicting the effect of adding heat (by way of thermal collector, or any other means) at any point in the cycle.

The operation diagram on every Chinese manufacturer website that I have seen, as well as the Solakool site, shows the 'solar collector' inserted into the refrigerant line between the compressor and the condenser. The hot, high-pressure refrigerant gas typically leaves the compressor at around 60 DegC. Ordinarily, that gas goes straight into the condenser, whose job it is to cool and therefore condense the gas. So, what would happen if the hot gas goes to the solar collector first? For additional heat to be added, as claimed, the collector would obviously need to be at a temperature above 60 degrees, probably at least 80 degrees to input any appreciable amount of heat. Already it becomes clear that the claim is nonsense. The flat panel 'collectors' are virtually always mounted vertically on the same wall as the condenser unit, frequently under the eaves, and preferably on a south-facing wall, for any competent installer knows that the compressor/condenser works best in the coolest, most shaded position available. The 'solar collector' instuctions say this is not a problem, as the collector only needs to be placed somewher at ambient temperature, not in direct sunlight. Well folks, ambient temperature is NEVER above 60 degrees, so straight away we see that the system simply could not work as claimed in the majority of installations.

OK, so what WOULD happen in a typical installation. That is easy to predict and understand. In nearly all situations, the flat plate collector would be in an environment of less than 60 degrees, and would therefore COOL the hot gas, in exactly the same way that the condenser cools the gas. In other words, as the flat plate and condenser are mounted side-by-side in the same environment, the 'collector' will function just as the condenser, removing heat from the hot gas, exactly as required to aid the refrigeration process. The condenser will do the job much better, because it has a huge surface area of forced-air-cooled fins. Nonetheless, both the 'collector' and condenser are coupled to ambient temperature, and the 'collector' can best be thought of as a kind of crude pre-cooler for the condenser and, if anything, will slightly increase the operating efficiency of the aircon system. Of course, this reasoning works equally well in reverse-cycle heating mode.

If for whatever reason the 'collector' really did get hot enough (>60 deg) to further heat the gas, then system efficiency would be slightly degraded because that extra heat would then need to be removed by the condenser. However, the manufacturers probably know perfectly well that that will not happen in any typical installation, and that the 'collector' almost never does any harm, and will typically even do a tiny amount of good. Much more importantly though, the 'solar collector', along with the term 'solar air conditioning', will sell the product.

I therefore conclude from theoretical considerations what I had already concluded on account of there being no reputable test results or existence in the literature. I'm sorry people, but when looked at from any angle, this method of 'solar aircon assistance' is nonsense.

What makes it possible for the myth to propagate even in best faith, is that the 'collector' is an add-on to a conventional aircon system that works just a well as competing systems, and the average user has no way of knowing whether the 'collector' is really helping or not.

Posted Saturday 21 Jan 2012 @ 11:19:16 am from IP #

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