Heat Pumps

Principle

Why heat pumps? 

Heat pumps are an excellent answer to the 20/20/20 objectives of the European Union to achieve: 20% less energy consumption, 20% reduction in CO2 equivalent emissions and 20% of energy from renewable energy sources by 2020. They will become even more important as we progress along the roadmap to a lower carbon economy by 2050. Heat pumps can assist in achieving these goals as they produce three to four times more energy than they consume, as they generate fewer CO2 emissions than fossil fuel based systems, and as they use renewable energy sources in form of latent energy from ground, water or air.

Heat pumps convert low-temperature heat into higher-temperature heat - even in winter when it is well below freezing. This process takes place in a closed circuit and involves constantly changing the state of the working fluid (evaporation, compression, condensation, expansion). Refrigerators operate on the same principle to extract heat from inside and discharge it to the outside. By contrast, heat pumps take stored solar heat from the environment around the house - soil, water or air - and release it together with the input energy in the form of useable heat to the heating and hot water circuit. 

Heat Pumps are

  1.  ENERGY EFFICIENT

For each kW of electricity consumed by a heat pump, about 4kW of thermal energy is generated. This corresponds to a 300% efficiency.

Comparison with other heating technologies:
Condensing gas/oil boiler: 90-96% efficiency
Conventional gas/oil boiler: 70-80% efficiency
Direct electric heating: 35-45% efficiency

        2. SUSTAINABLE

About 75% of the energy that is used is renewable, whereas 25% of the energy is generated by other sources (in 99% this is electricity). If the electricity is generated by renewables (PV, wind, hydro), then the heat pump is 100% renewable and CO2-neutral. They contribute to an annual reduction of 9,16 million tons CO2 emissions in the EU. According to IEA, heat pumps could save 50% of the building sector's CO2 emissions, and 5% of the industrial sector's. This means that 1.8 billion tonnes of CO2 per year could be saved by heat pumps.

       3. EUROPEAN

The vast majority of the heat pumps installed in Europe are also manufactured in Europe. In fact, the EU heat pump companies play a leadership role in the technology development. (EHPA). They foster EU employment: 40 358 Europeans are full-time working in the heat pumps sector. This is a very moderate estimation based on the sales data in Europe, on which we applied a certain factor: man-hours needed to install the different types of heat pumps. (EHPA)

     4.  THEY PROVIDE ENERGY SECURITY

The EU imports annually energy worth over 400 billion euro. Heat pumps reduce the use of primary and final energy. So we would need less energy and by consequence less would need to be imported. This saves costs and secures the supply of energy at the same time: we become more energy independent.

Text credit to: European Heat Pump Association @ http://www.ehpa.org/technology/key-facts-on-heat-pumps/

The heat pump cycle

The heat pump operates on the basis of a working fluid (coolant) which changes state (liquid/gas) in a continuous cycle and absorbs and releases heat.

The heat pump cycle is essentially based on the Carnot cycle.

  1. Evaporation
    In a heat exchanger the liquid refrigerant absorbs energy from the heat source (water, soil or air) and evaporates as the temperature rises.
     
  2. Compression
    In a compressor the introduction of electrical energy causes the vaporised but still cold coolant to compress and heat up. The coolant leaves the compressor as a hot gas.
     
  3. Liquefaction/condensation
    The hot gas flows into the liquefier, releases energy to the heating system, condenses and leaves the condenser as hot, liquid refrigerant. This energy heats the hot water for heating or domestic use to the desired temperature.
     
  4. Expansion
    The hot, liquid refrigerant is transferred to the expansion valve. In the expansion valve the pressure is reduced very rapidly. The temperature of the coolant also drops very quickly without releasing energy. The cold, liquid refrigerant is transferred to the evaporator and the cycle begins again.


 

Interested in more details? Read the full booklet from European Heat Pump Association here: http://www.ehpa.org/media/studies-and-reports/?eID=dam_frontend_push&docID=1930 

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