Compression and absorption heat pumps are the two main types
of heat pumps, and they differ in internal architectures and working
principles. Compression heat pumps are reliant on mechanical energy driven by
electricity to power a compression within the heat pump. On the other hand,
absorption heat pumps run heat as an energy source. This heat can be produced
from electricity, fuel-burning sources as well as naturally occurring heat
sources. Regardless of the type, a heat pump is often more efficient in terms
of energy than a gas furnace. However, it produces less heat and is appropriate
for low-heating applications.
There are finer divisions in the heat-pump family which branch
into the following:
·
Air-to-Water: Electricity is used to
drive a refrigeration compressor.
·
Air Source Heat Pumps: These heat pumps
get energy from the surrounding air, and are drawn across the heat exchanger
within the unit. In this case, the temperature is highly dependent on the
ambient temperature, and the weather itself.
·
Ground Source Heat Pumps: Here the
working principle is like that of a geothermal power station, in the sense that
the heat pump itself draws energy from groundwater, which maintains a constant
temperature throughout the year. This heat is augmented with fuel-burning
sources to improve the fuel economy of the heat pump.
·
Water Loop Heat Pumps: Waterflow from
rivers is used as the heat source/sink for this type of heat pumps.
See the summary of this part in this infographic – 4
Basic Types of Heat Pumps [Infographic]
About Absorption Heat Pumps
Absorption heat pumps rely on a thermodynamically sealed
circuit which contains a special ammonia-water solution acting as the medium
for heat transfer. In this solution, the ammonia acts as the primary
refrigerant and the water allows heat to be absorbed. This is a stark contrast
to the traditional refrigerants used by air-to-water electric heat pumps or air
conditioners wherein fluorinated refrigerants (most commonly the R410A
refrigerant) is used. Although they are known to have a less damaging impact on
the environment, there is still a significant amount of global warming
potential associated with these refrigerants. Therefore, their use is not
completely harmless. On the other hand, ammonia is naturally forming a chemical
with virtually no impact on the ozone layer. Moreover, the combined water and
ammonia solution features zero ODP and zero GWP, with virtually no
environmental impact.
There are some drawbacks to using ammonia for residential
purposes, however. With ammonia refrigerant being toxic and flammable, heat
pump installations in a commercial context are often installed outdoors, and
come with sealed ammonia circuits. Therefore, contact with the dangerous fluid
is minimized during service and maintenance runs. Moreover, with the use of a
sealed system to contain the ammonia refrigerant, it is less likely t hat the
flammable ammonia will escape into the surrounding atmosphere and pose a threat
to people. Despite these benefits, it is often not possible in a residential
setting wherein the main heat pump unit is located somewhere within the home or
near people.
The Working Principle of an Absorption Heat Pump
The function of an absorption heat pump is dependent on a
well-orchestrated heat exchange mechanism based around heat exchangers,
condensers, evaporators and an ammonia-water solution.
The ammonia refrigerant of the heat pump is initially expanded
before being pumped into the evaporator at low pressure and temperature. Much
like an air-source heat pump, heat is drawn from the surrounding air to
evaporate the ammonia.
To introduce more heat into the system, a gas burner is
lighted (as is the case in most gas-absorption heat pumps), and the ammonia
refrigerant is heated further. Once the ammonia from the refrigerant solution
has evaporated, it is guided into the condenser chambers, and exchanges heat
with the water from the main heating system. Due to the heat absorption by the
water, the ammonia evaporates condenses again and is returned to the evaporator
chamber. Here, the cycle restarts as the ammonia heats up and evaporates once
again.
The water in the solution acts as the absorber for the
ammonia once it has been condensed again. This reabsorption generates more heat
and is recirculated by the heat pump. It’s important to note that, this
absorbent water is completely different from the exchanger’s water supply and
serve different purposes within the absorption heat pump.
Bottom Line
Gas-absorption heat pumps function as high-efficiency
solutions to low-requirement heating and can be used with traditional boilers
for reduced emissions and economical ratings. Their functionality is simple and
provides a lower cost, and smaller carbon footprint solution to heating through
heat pumps.
If you are looking for HVAC equipment at an affordable rate,
you can check out HVAC Wholesales
for best offers.
We have Trane 14 SEER
HVAC Systems, Trane 16 SEER
HVAC Systems, Trane
17 SEER (& Up) HVAC Systems and Heat Pumps
among other HVAC components.
Also, look no further for your HVAC repair and maintenance needs. Just contact us and we will be there for you.