Civil Engineering Reference
In-Depth Information
the heat transfer fluid in the range of 60-80 C. However, the overall heat transfer
of solar heat storage depends primarily on the net surface area of collector.
In addition, due to the inherent thermal stresses, related convective and radi-
ation heat-loss effects, the solar radiation absorbed by the flat plate and evacuated
collectors can be converted to useful heat energy to only some extent, which might
not be sufficient to cater the heat duty in buildings during off-sunshine periods.
Solar heat storage can be made effective in buildings by incorporating concen-
trated solar collector module using parabolic or conical reflectors that would
enhance the total heat transfer process between the collector and the storage tank.
By pointing out the collected heat source on the receiver tubes, the temperature
of heat transfer fluid is expected to elevate up by 130-140 C. For improved
performance of the solar heating storage system, the solar collector has to be
aligned towards 30 due South face with appropriate latitude correction of the
building. Installation of concentrated solar collector might have cost-related issues,
but they are much efficient than the flat plate and evacuated tube collectors.
The thermal storage systems designed to cater both space heating and hot water
supply in buildings can be effectively tuned for its maximum performance, if they
are coupled with high-operating-temperature parabolic or conical type solar
reflectors or collectors. In order to satisfy the heating load demand in buildings on
year-round basis, the concentrated solar collectors with the thermal efficiency
greater than 60 % is most viable when compared to the flat plate and evacuated
tube receivers with the thermal efficiency of 40-50 %.
4 Seasonal (Source) Thermal Energy Storage Technologies
The seasonal or source TES offers a promising way of storing cold or heat energy that
is chiefly available from the energy sources including aquifers, earth, geothermal,
lakes, ponds, caverns, sea water, rock structures, waste heat, cogeneration, etc.
The intention behind the development of seasonal TES technologies in buildings
is primarily to redistribute or shift the cooling/heating demand from on-peak load
conditions to off-peak conditions, reduce the peak electricity demand issues, reduce
GHG emissions and achieve economic feasibility in large installations including
district cooling and heating systems. For brevity, only some of the aforementioned
source-based TES technologies are explained in the forthcoming sections.
4.1 Aquifer Thermal Energy Storage
The aquifer thermal energy storage (ATES) system basically works on the principle
of extracting the enthalpy of thermal energy from the low-temperature groundwater
to cater the cooling or heating load demand in buildings. The schematic represen-
tation of the ATES system is shown in Fig.
4
. The ATES system essentially consists
of aquifer well, heat exchangers, pumps and other necessary installation accessories.
