Absorption heat pump
Heat pumps transfer heat from a lower temperature source to one of a higher temperature. This is the opposite of the natural flow of heat and is the same process that is used to extract heat from a fridge.
Heat pumps can be used domestically or commercially to provide hot water, space heating, or other applications such as heating swimming pools.
Generally heat pumps work using compression, and are powered by electricity. A refrigerant fluid is run through the lower temperature source. The fluid ‘absorbs’ heat and boils, even at temperatures below 0° C. The resulting gas is then compressed, which increases its temperature further. The gas is passed into heat exchanger coils, where it condenses, releasing its latent heat. The process then repeats.
Absorption heat pumps work on a similar basis, with a refrigerant that boils at low temperature and pressure, however, in this case, the refrigerant gas (generally ammonia) is then absorbed in a solution (the ‘absorber’, generally water) which is then heated in the ‘generator’ so that the refrigerant evaporates again, but this time at a higher pressure and temperature. It is then condensed through a heat exchanger, heating ‘cool’ return water from the building, and the process then begins again.
The heat source is generally gas-fuelled and so they can also be referred to as a gas absorption heat pump (GAHP). This process is more efficient than a traditional gas-powered boiler.
Other heat sources can be used, such as combined heat and power plant (CHP), solar heated water, (although this requires specialist flat plate collectors that raise the temperature of the water above that normally required), geothermal heat, district heat networks and so on.
Absorption heat pumps are most efficient when supplying low-temperature hot water, such as for underfloor heating. They may be used in combination with conventional boilers to produce higher-temperature water.
Unlike some refrigerants used in compression heat pumps, ammonia is not an ozone depleting gas or a global warming gas. However it is flammable and toxic, and so units are generally hermetically sealed rather than engineered systems and are located outside.
Absorption chillers and absorption refrigerators work on the same principal as absorption heat pumps, but with the flow of heat reversed, so that heat is absorbed from the interior and rejected to the exterior.
[edit] Related articles on Designing Buildings
- Absorption refrigeration.
- Air handling unit.
- Air source heat pumps.
- BSRIA domestic hot water heat pumps testing.
- Coefficient of Performance CoP.
- Dynamic thermal modelling of closed loop geothermal heat pump systems.
- Earth-to-air heat exchangers.
- Exhaust air heat pump.
- Gas absorption heat pump.
- Geothermal pile foundations.
- Ground energy options.
- Ground source heat pumps.
- Heat pump.
- Renewable energy sources: how they work and what they deliver: Part 3: Electrically driven heat pumps DG 532 3.
- Room-based heat pumps.
- Solar-assisted heat pump.
- Solar thermal heating.
- Water source heat pumps.
Featured articles and news
ECA 2024 Apprentice of the Year Award
Entries open for submission until May 31.
UK gov apprenticeship funding from April 2024
Brief summary the policy paper updated in March.
For the World Autism Awareness Month of April.
70+ experts appointed to public sector fire safety framework
The Fire Safety (FS2) Framework from LHC Procurement.
Project and programme management codes of practice
CIOB publications for built environment professionals.
The ECA Industry Awards 2024 now open !
Recognising the best in the electrotechnical industry.
Sustainable development concepts decade by decade.
The regenerative structural engineer
A call for design that will repair the natural world.
Buildings that mimic the restorative aspects found in nature.
CIAT publishes Principal Designer Competency Framework
For those considering applying for registration as a PD.
BSRIA Building Reg's guidance: The second staircase
An overview focusing on aspects which most affect the building services industry.
Design codes and pattern books
Harmonious proportions and golden sections.
Introducing or next Guest Editor Arun Baybars
Practising architect and design panel review member.
Quick summary by size, shape, test, material, use or bonding.
Types of rapidly renewable content
From forestry to agricultural crops and their by-products.
Terraced houses and the public realm
The discernible difference between the public realm of detached housing and of terraced housing.