Absorption heat pump
Absorption heat pump
Absorption heat pump is essentially an air-source heat pumps driven not by electricity, but by a heat source such as solar-heated water, or geothermal-heated water. There are also absorption coolers available that work on the same principle, but are not reversible and cannot serve as a heat source.
Solar thermal
Active solar cooling wherein solar thermal collectors provide thermal energy to drive thermally-driven chillers (usually ADsorption or ABsorption chillers).
The solar thermal energy system can be also used to produce hot water.
There are multiple alternatives to compressor-based chillers that can reduce energy consumption by 80%, with less noise and vibration. Solar thermal energy can be used to efficiently cool in the summer, and also heat domestic hot water, and the building in the winter. The Audubon Environmental Center in Los Angeles is one example among many).[2] Single, double or triple iterative absorption cooling cycles are used in different solar-thermal-cooling system designs. The more cycles, the more efficient they are.
In the late 1800s, the most common phase change refrigerant material for absorption cooling was a solution of ammonia and water. Today, the combination of lithium and bromide is also in common use. One end of the system of expansion / condensation pipes is heated, and the other end gets cold enough to make ice. Originally, natural gas was used as a heat source in the late 1800s. Today, propane is used in recreational vehicle absorption chiller refrigerators. Innovative hot water solar thermal energy collectors can also be used as the modern "free energy" heat source.
Efficient absorption chillers require water of at least 190 °F (88 °C). Common, inexpensive flat-plate solar thermal collectors only produce about 160 °F (71 °C) water, but several successful commercial projects in the US, Asia and Europe have shown that flat plate solar collectors specially developed for temperatures over 200 °F (featuring double glazing, increased backside insulation, etc.) can be effective and cost efficient. Evacuated-tube solar panels can be used as well. Concentrating solar collectors required for absorption chillers are less effective in hot humid, cloudy environments, especially where the overnight low temperature and relative humidity are uncomfortably high. Where water can be heated well above 190 °F (88+ °C), it can be stored and used when the sun is not shining.
For 150 years, absorption chillers have been used to make ice (before the electric light bulb was invented). This ice can be stored and used as an "ice battery" for cooling when the sun is not shining, as it was in the 1995 Hotel New Otani in Tokyo Japan. Mathematical models are available in the public domain for ice-based thermal energy storage performance calculations.
The ISAAC Solar Icemaker is an intermittent solar ammonia-water absorption cycle. The ISAAC uses a parabolic trough solar collector and a compact and efficient design to produce ice with no fuel or electric input, and with no moving parts.
Makers include ClimateWell, Fagor-Rotartica and Daikin. From Wikipedia, the free encyclopedia