Solar Hybrid Reverse Cycle Air Conditioners
Solar Hybrid Reverse Cycle Air Conditioners
(OP)
Not strictly a work related question, but more of a curiosity, and if theres likely to be a sensible answer, its here.
I've seen a number of advertisements recently regarding 'Solar Hybrid Reverse Cycle Air Conditioners'. Usual sort of thing, various quotes on efficiency improvements over standard reverse cycle air conditioners, inverter or DOL notwithstanding.
It appears that these devices operate by including a solar panel (though not an electrical type, rather the same sort of thing as found in a hot water system) in the refrigerant loop, usually before the compressor. A link to a typical supplier is here
With my somewhat limited understanding, I can't see how these would provide benefit in cooling a building. I can see that it'd be handy to gain extra heat from the sun if you're intending to heat the building but I can't see any benefit in using the sun to heat the refrigerant before it goes into the compressor. These units are also being advertised in my location which is in the Northern part of Australia, typically where air conditioners are not reverse cycle. They don't state any sort of absorption method being used, though it might be possible.
Any thoughts on whether this is a real development in terms of AC technology, or just another snake oil trend?
I've seen a number of advertisements recently regarding 'Solar Hybrid Reverse Cycle Air Conditioners'. Usual sort of thing, various quotes on efficiency improvements over standard reverse cycle air conditioners, inverter or DOL notwithstanding.
It appears that these devices operate by including a solar panel (though not an electrical type, rather the same sort of thing as found in a hot water system) in the refrigerant loop, usually before the compressor. A link to a typical supplier is here
With my somewhat limited understanding, I can't see how these would provide benefit in cooling a building. I can see that it'd be handy to gain extra heat from the sun if you're intending to heat the building but I can't see any benefit in using the sun to heat the refrigerant before it goes into the compressor. These units are also being advertised in my location which is in the Northern part of Australia, typically where air conditioners are not reverse cycle. They don't state any sort of absorption method being used, though it might be possible.
Any thoughts on whether this is a real development in terms of AC technology, or just another snake oil trend?





RE: Solar Hybrid Reverse Cycle Air Conditioners
RE: Solar Hybrid Reverse Cycle Air Conditioners
RE: Solar Hybrid Reverse Cycle Air Conditioners
MintJulep, I believe we're talking about the same thing. Most ACs (at least the smaller domestic split systems) are used for cooling most of the time, reverse cycle refers to reversing the system thus using it for heating (thus the same thing). What I can't understand is why they'd want to market the units in an area where 'reverse cycle' often isn't installed as theres no need for heating, if thats the only benefit of having the panels.
RE: Solar Hybrid Reverse Cycle Air Conditioners
It is the amount of saved energy vs the additional cost of the system that is the dubious part. Compressed refrigerant is already rather hot, so I doubt there would be much in the way of savings. When I opened your link I was expecting to see the solar cell on the compressor inlet where you'd think it would do more work.
RE: Solar Hybrid Reverse Cycle Air Conditioners
RE: Solar Hybrid Reverse Cycle Air Conditioners
RE: Solar Hybrid Reverse Cycle Air Conditioners
as far as i can comprehend, heat is introduced after evaporator, i.e. at compressor suction.
take a look at refrigeration cycle in wiki:
http://en.wikipedia.org/wiki/Heat_pump_and_refrige...
if point 1 is raised, i.e. temperature at suction is raised, this also means that compressor entrance enthalpy is raised. enthalpy lines are sloped, becoming parallel to saturation line, so that is not proportional increase, yet it is increase.
a compressor work equals enthalpy difference, so with fixed compressor outlet state point - entrance to condenser - higher compressor entrance enthalpy will mean less compressor work.
this is pretty apparent in refrigeration cycle diagram, but how it works in reality, that is another story. this is new concept and issues of actual efficiency, return on investment, reliability etc. are yet to be found.
RE: Solar Hybrid Reverse Cycle Air Conditioners
It's thermodynamically reasonable.
It is absolutely NOT 4 hours of sun = 15 hours of run time.
RE: Solar Hybrid Reverse Cycle Air Conditioners
though, i admit to not fully understand how it works in such case. the whole process after compressor up to expansion valve lays on the same isobar. how can solar exchanger increase pressure? there should be some valve which separates pressure conditions between compressor outlet and rest of cycle up to expansion valve.
the other possibility is that there is interaction between compressor and solar heater, so solar heating changes compressor curve, though i am not sure can it be presented by method other than probe measuring.
RE: Solar Hybrid Reverse Cycle Air Conditioners
At least some part of that enthalpy could be exhibited as a pressure increase. Although most of it probably goes to increasing the superheat, which isn't very useful at increasing efficiency.
RE: Solar Hybrid Reverse Cycle Air Conditioners
RE: Solar Hybrid Reverse Cycle Air Conditioners
http://www.eng-tips.com/viewthread.cfm?qid=348557
I today got an email claiming I would get $4.5 instantly and $10K monthly as soon as I wire the $250 processing fee to them (not sure why they just deduct that from my "for sure" $4.5 mio). I would put these solar assisted refrigeration cycles into the same category.