Page 59 - Low Temperature Energy Systems with Applications of Renewable Energy

48 Low-Temperature Energy Systems with Applications of Renewable Energy

Fig. 2.1 Schematic flow diagram of a heating system with an “air-water” heat pump: 1, heat
network; 2, heating system; 3, cold water pipe; 4, hot water supply system; 5,6, first and second
stage water heaters; 7, circulating pump; 8, “air-water” heat pump; 9, heat storage tanks - hot
water accumulators; 10, condenser feed pump.

implementing a heat-pump heating system for a 4-story office in Kiev, Ukraine. That
project uses an off-the-shelf heat pump of the “air-water” type which was placed in a
special technical room on the upper floor rather than on the building roof. Fresh air is
taken out of the air intake shaft by air handling units, heated inside them, and forced
into the heated rooms. Return air goes by means of a ventilation system into the tech-
nical room where the heat pump is located. As a result of mixing with ambient air, it
is expected that the air temperature at the evaporator input will not be lower

than 15 C during the coldest season. Heating the building rooms is done by means
of externally supplied air convectors-conditioners, connected with the heat pump by
heat-cold-supply pipelines. In summer the heat pump operates like a refrigerator with
condenser air-cooling, but externally supplied air conditioners provide all rooms with
conditioned air.
Real possibilities of temperature range expansion using space-conditioning heat
pumps come about by using ambient air when water crystallization heat is
employed to preheat air; these will be discussed below. The effectiveness and
economy of using space conditioning heat pumps with the use of ambient air and
the heat of water crystallization increases as a result of using night electric power
rates (where available) that are lower than day-time rates, allowing for
more cost-effective ice storage for use in air conditioning systems in summer
(see Section 2.9).