Heat pumps and how they work
Heat pump technology itself has been around for many years, however most people know very little about it. With fuel costs and our concern for the 'carbon footprint' being at an all-time high, these past few years have seen a significant leap forward in the development of heat pump systems, both in terms of their efficiency and the number of applications that they are being applied to.
how do heat pumps work?
Within a conventional refrigeration system, heat is absorbed into the internal heat-exchanger (known as the evaporator) which increases the temperature of the cold refrigerant flowing through it. This refrigerant is then compressed, increasing its temperature further to around 75°C. This hot refrigerant then passes through an external heat-exchanger (known as the condenser) where the heat energy collected within the evaporator (in addition to that added during the compression process) is rejected to a place where it is unobjectionable (generally being outside).
The refrigerant leaving the condenser is then much cooler (around 40°C), and after being forced to undergo a significant pressure drop, reduces its temperature further still (to around 0°C) prior to re-entering the evaporator to collect more heat from the space being cooled down.
The refrigerant does not however stay in a constant state as it's circulated around the system. It enters the evaporator as liquid and leaves as a vapour, and enters the condenser as a vapour and leaves as a liquid, hence the internal heat-exchanger being referred to as an 'evaporator' and external heat-exchanger being referred to as a 'condenser'.
It is these 'changes of state' that makes the refrigerant extremely efficient at collecting heat from the evaporator and rejecting it at the condenser.
A heat pump system is effectively a refrigeration circuit with the flow of refrigerant reversed, hence the term 'reverse cycle'.
With a heat pump system, the internal and external heat-exchangers effectively swap places within the refrigeration circuit. Low temperature refrigerant is now pumped into the external heat-exchanger, and heat from the outside air is absorbed into it. The refrigerant then leaves the external heat-exchanger warmer than it entered, and is then compressed to further increase its temperature to around 75°C. This hot refrigerant then passes through the internal heat-exchanger where the heat collected from the outside air and compression process is rejected to the indoor space requiring heating.
why are heat pumps so energy-efficient?
Here's the fundamental brilliance of a heat pump system:
The amount of heat energy available for rejection at the condenser is several times greater than the amount of electrical energy consumed by the heat pump system itself.
In the past, the heat-output / electrical input ratio of a heat pump system was always regarded as approximately 3:1. With today's heat pump systems now being more efficient than ever, a ratio of more than 5:1 is possible.
Therefore, more than 5kW of heat-output can be gained from 1kW of electrical input, which is hugely energy-efficient in comparison with any other form of electric heating.
To find out more about how heat pump air conditioning systems can reduce your energy bills, contact us via our contact page or call us on 0118 930 4404.
We look forward to speaking with you soon.
