Absorption heat pump
Encyclopedia
Absorption heat pump is essentially an air-source heat pump
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.
In the late 19th century, the most common phase change refrigerant
material for absorption cooling was a solution of ammonia
and water. Today, the combination of lithium bromide
and water 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 19th century. 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 collector
s only produce about 160 °F (70 °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.
as opposed to a burner to create heat, it would be theoretically possible to create an air-conditioner which converted approximately 55% of the fuel (assuming a methane
fuel cell) to electricity and the rest to driving an air-conditioner.
Heat pump
A heat pump is a machine or device that effectively "moves" thermal energy from one location called the "source," which is at a lower temperature, to another location called the "sink" or "heat sink", which is at a higher temperature. An air conditioner is a particular type of heat pump, but the...
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
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 19th century, the most common phase change refrigerant
Refrigerant
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase change from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion...
material for absorption cooling was a solution of ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
and water. Today, the combination of lithium bromide
Lithium bromide
Lithium bromide, or LiBr, is a chemical compound of lithium and bromine. Its extreme hygroscopic character makes LiBr useful as a desiccant in certain air conditioning systems.-Production and properties:...
and water 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 19th century. Today, propane
Propane
Propane is a three-carbon alkane with the molecular formula , normally a gas, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves, and residential central...
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 collector
Solar thermal collector
A solar thermal collector is a solar collector designed to collect heat by absorbing sunlight. The term is applied to solar hot water panels, but may also be used to denote more complex installations such as solar parabolic, solar trough and solar towers or simpler installations such as solar air...
s only produce about 160 °F (70 °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
Parabolic trough
A parabolic trough is a type of solar thermal energy collector. It is constructed as a long parabolic mirror with a Dewar tube running its length at the focal point. Sunlight is reflected by the mirror and concentrated on the Dewar tube...
solar collector
Solar collector
-See also:*Solar thermal collector*Solar water heating*Solar air heating*Photovoltaic module*Renewable heat*Concentrating solar power...
and a compact and efficient design to produce ice with no fuel or electric input, and with no moving parts.
Makers include ClimateWell
ClimateWell
ClimateWell, or CW, is a multinational cleantech company headquartered in Stockholm, Sweden. The company and its business partners install energy efficient solar energy solutions that provide cooling and heating, plus heat tap water in commercial buildings, hospitals, factories, hotels, offices,...
, Fagor
Fagor
Fagor is a large domestic and commercial appliance manufacturer based in the Basque Country, Spain. It is run by the Mondragon Corporation and is one of the fastest growing businesses in European Union...
-Rotartica and Daikin.
Other
By using a fuel cellFuel cell
A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes used...
as opposed to a burner to create heat, it would be theoretically possible to create an air-conditioner which converted approximately 55% of the fuel (assuming a methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
fuel cell) to electricity and the rest to driving an air-conditioner.
See also
- Absorption refrigeratorAbsorption refrigeratorAn absorption refrigerator is a refrigerator that uses a heat source to provide the energy needed to drive the cooling system...
- Geosolar
- Geothermal heat pump
- Solar air conditioningSolar air conditioningSolar air conditioning refers to any air conditioning system that uses solar power.This can be done through passive solar, solar thermal energy conversion and photovoltaic conversion . The U.S...
- Solar thermal cooling
External links
- Absorption Heat Pumps (EERE)