S2S
Thanks for the info. But on refrigeration compressors, even though the electric motor components are +90% efficient, the compressors are substantially less. Do you have any figures for AC compression efficiency? Typical air compressors are under 50% eff., most even run at 10%, so theoretically a doubling of COP is possible from what is considered the norm just by employing better compressors, even if they "must" conform to energy conservation principles. I would like to know what the max compressor eff. is in AC units, but I haven't found much info on them so far.
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@All
Using the both sides of the heat pump is a logical step. Have a look at this link for a common AC with hot water heat exchanger, that has this function.
http://www.alibaba.com/product-gs/249698111/Hot_water_heat_pump_air_conditioner.html
I think the important thing to understand with all of these devices is that they do not make heat, they only forcefully transport it from one location to another. It's a bit like filling up a water tank with a bucket, the bucket you are using does not make any water, it only collects it from one place and puts it in another. A heat "pump", like a "water pump", does the same with heat.
In any event it will create a potential temperature difference to ambient temperature, it will make one side colder than ambient, by removing the heat there and moving it to a warmer than ambient one, making that one even warmer. For any AC condenser or evaporator to function effectively, they need to have a relatively high temperature difference to the medium they are absorbing heat from (ie cooling) or dissipating heat to (ie Heating). The smaller the temperature difference to the medium, the less effective they become. That is why it is so important to operate all forms of heat pumps from optimal ambient mediums. Earth tube and/or hydronic thermal storage systems can greatly improve their effectiveness by introducing a "constant" and reliable base temperature medium from which to "heat pump" from. Hydronic type systems also allow for "harvesting" at the most advantageous times. For example running the AC at night when ambient air is cooler, and storing it in a insulated thermal store for hot daytime use, like this one:
http://www.ice-energy.com/ice-bear-energy-storage-system
For heating the opposite type system can be used to harvest daytime max temperatures for use at night, via an insulated HWS type water store. Solar can also be used to further add heat if the weather permits.
I have grown to the understanding that in warm weather one can harvest energy from the environment to maintain interior climate, however, in cold weather there is less readably available energy, especially with cloud cover, and therefore one tends to require the addition of "artificial" fuel sources ie timber.
Initially this type of system might seem overally complex, but if all these components are streamlined into one overall unit, the cost can be significantly reduced, and it's functionality and efficiency increased.
One of the things I have been considering is using only the water thermal mass as a "heat/cold battery" for all household type devices, from fridges to ovens, AC cooling to HWS and climate control etc. By de-coupling the operating times and the operating temperatures of heat pumps from demand, the gains, especially for those on cheap night time tariffs can easily repay the capital investment costs. The reason I came about this was from some designs, which resulted in us finding that water, with an added coolant to restrict it from boiling/freezing, can store more heat/cold energy than a equivalent battery, at the cost of only a simple insulated water tank. Plus the heat/cold stored can easily be distributed for refrigeration/climate control/HWS with minimal losses and little equipment, as a simple closed circuit water pump and valves with temperature sensors was sufficient.
As for peltier elements they have yet to achieve a COP of 1.
There is another better device however for this called a thermoacoustic engine/pump.
See here: http://en.wikipedia.org/wiki/Thermoacoustic_hot_air_engine
or a third world version (named "SCORE")here:
http://www.score.uk.com/research/default.aspx
Some local development here:
http://www.mecheng.adelaide.edu.au/avc/thermoacoustics/
Posted Saturday 12 Mar 2011 @ 6:07:36 am from IP
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