Civil Engineering Reference
In-Depth Information
Table 9 Key parameters of various active TES systems (Parameshwaran et al.
2012
)
TES system
Energy storage
capacity (kWh/t)
Discharge
ability (kW)
Efficiency (%)
Storage
period
Chilled water storage
20-80
1-10,000
50-90
Day-year
Aquifer storage
5-10
500-10,000
50-90
Day-year
Borehole storage
5-30
100-5,000
50-90
Day-year
Ice storage
100
100-1,000
80-90
Hour-week
PCM storage
50-150
1-1,000
75-90
Hour-week
8 Sizing of Thermal Energy Storage System
The design of TES system for cooling and heating applications in buildings can be
performed by determining the following:
• Thermal load profile of the building for the design day's operation.
• Type of TES system (full or partial storage).
• Heat storage material considered.
• Active or passive system.
The following examples explain the basic sizing of ice and chilled water cool
TES systems dedicated to provide energy redistribution requirements in buildings:
8.1 Ice Thermal Energy Storage System Design
The simple design of an ice TES system is explained below:
Design inputs:
Cooling energy requirement (on daily basis)—5,000 kWh
Charging time of the ice storage—8 h
Discharging time of the ice storage—10 h
Peak cooling load observed in building—700 kW
Rotary screw chiller is considered
Calculation of ice storage capacity:
Assuming the energy storage efficiency factor to be 0.94 with a storage capacity of
50 %, the per day energy generation requirement can be obtained by
5,000 9 (50/100) = 2,500 kWh
Applying the storage efficiency factor, the energy generation = (2,500/0.94)
Otherwise, the total energy storage capacity & 2,660 kWh
Charging of ice storage for 8 h using the chilled water, which gives out the chiller
capacity = 2,660 kWh/8 h = 333 kW
Thus, the cooling duty of the chiller during the design day's operation is deter-
mined by: Ice storage discharge time = 2,660 kWh/10 h = 266 kW
Maximum cooling load in the building = 700 kW
