Page 91 - Low Temperature Energy Systems with Applications of Renewable Energy

80 Low-Temperature Energy Systems with Applications of Renewable Energy

has its advantages, disadvantages, and limitations, i.e., temperature level and volume,
design features of the plant, cost, and reliability. Nevertheless, it has been demon-
strated that the use of heat pumps can significantly reduce the overall energy consump-
tion of buildings in an economically favorable manner.
Atmospheric air is the most available source of low-temperature heat. In the US, the
most widely used type of heat pump is the air-to-air design, with a share of more than
80%. About 77% of heat pumps installed in Europe use atmospheric air. In Southern
Europe, air-to-air split systems are used in the heating/air-conditioning mode. Howev-
er, air-to-air heat pumps are characterized by a seasonal load factor or seasonal perfor-
mance factor (SPF), which reduces their efficiency on average by about 10e30%
compared to water-to-water heat pumps. This is caused by:

• Significant reduction in capacity and productivity with decreased temperature of atmospheric
outside air
• Relatively large difference in evaporation and condensation temperatures during the lowest
winter temperatures
• Energy costs for defrosting the evaporator surface (at temperatures from 0 to 6 C) and fan

power consumption.
In Northern Europe, heat pumps are used for heating and hot water supply. In Nor-
way, the share of air heat pumps is 67%, while 19% of them use water and ground heat.
In Finland, water-to-water systems predominate; the heat source is soil and lakes. In
Sweden, heat pumps are the main technology in heating. Ground-source models pre-
vail with a large number of air heat pumps [13]. In Switzerland and Austria, heat
pumps using the heat of soil (40% and 82%, respectively) predominate.
According to the European Heat Pump Association (EHPA), the number of heat
pumps installed in Europe is about 10 million units [14]. In 2015 the sales level
was 880,179 units; a 25% growth is observed in the air-to-air segment as well, but
air-to-water heat pumps show the most significant growth, namely, the number of sales
has increased by 6e7 times compared to year 2014. The use of heat pumps is mainly
concentrated in the following countries: France (209,000), Italy (121,000), Sweden
(103,000), Spain (83,000) and Germany (70,000), using data for 2015. Asia remains
the driving force of the heat pump market, accounting for 78% of the world sales:
about 1.9 million units, mostly air-to-water units.
It is clear that heat pump technology is being widely developed, and new construc-
tion and reconstruction of buildings offer great opportunities for the use of heat pumps
in the future.

Nomenclature

Symbols and acronyms
A defined factor, a function of given values
APS atomic power stations
C compressor