Civil Engineering Reference
In-Depth Information
Herein, the water from the hot well is transported to the cold well of the aquifer
system through the evaporator of the heat pump unit being integrated with the
building floor hydronic heating system. The water loop of the heat pump picks up
the heat from the evaporator, and it is then transferred to the condenser section.
The cumulative of heat energy gained by the water in the heat pump loop is
then transferred to the floor hydronic water circuit from the building side. Hence,
the overall heat load demand in the building is effectively catered by the combined
seasonal thermochemical thermal energy storage systems. The major achieve-
ments in the Task 32 of the IEA programme dealing with the advanced storage
concepts for solar and low-energy buildings are summarized in Table
5
.
5 Ice Latent Thermal Energy Storage
The concept of ice TES has been into practice for many years, which by the
principle satisfies the building energy redistribution requirements either in full or
partial modes of operation. The cooling energy demand occurring in buildings
during on-peak load conditions can be effectively met using ice thermal storage
systems. The storage of cold thermal energy in the form of ice banks or ice-on-coil
arrangements would possibly shift or level the fluctuating cooling load demand
from on-peak to off-peak load conditions in buildings.
In principle, ice thermal storage systems effectively utilize the enthalpy of
fusion of water to store or release heat energy based on demand load conditions.
The chiller (or the cooling plant) installed in the building initially cools down the
brine solution (typically glycol solution) during off-peak load conditions, which in
turn is pumped through the cooling coil arrangement provided inside the storage
tank filled with water.
During the course of time, the water over the coil absorbs the cold energy from
the brine solution by combined conductive-convective modes of heat transfer and
starts to crystallize over the surface of the coil in the form of thick ice layers. In the
daytime, once peak load condition shoots up, warm water from the secondary loop
being coupled with the storage tank is pumped through the ice coil; thereby the ice
layers undergo melting process. By this, the cold energy stored can be effectively
retrieved from the ice storage systems for catering the cooling energy requirements
in buildings.
A standard chiller plant designed for low-temperature operating conditions can
be configured with the ice storage for producing the required quantity of ice during
the charging cycle. Generically, the functional aspects of an ice storage system
depend on the latent heat of fusion of water, and so the volumetric storage capacity
of such system is higher when compared to that of a standard chiller-based TES
system.
Besides, the energy consumption of an ice storage system may vary from 15 to
20 %, since the COP of the chiller associated with the ice storage system would be
less at the cost of incremental pumping power requirements. However, an ice
