Thermal Energy Storage Technologies - Nearly Zero Energy Building Refurbishment - page 517

Therefore, the chiller nominal capacity = 700 - 266 = 434 kW

Hence, the chiller plant selected for catering ice storage at 380 kW is capable of
offsetting the thermal load demand and redistributes the energy requirements in
building at 50 % higher capacity during its daytime operation, that is, the cooling
capacity of the chiller is expressed to be (333 kW 9 1.5) & 500 kW.

8.2 Chilled Water-Packed Bed Thermal Energy Storage
Systems Design

The basic design of the chilled water-packed bed LTES system for the building
located in a hot and humid climatic condition is represented in Table 10 . The
on-peak and part-load conditions existing in the building are highlighted by
the orange and blue colours, respectively. The total cooling load requirement of
the building was estimated to be 6,186 kW, wherein the nominal cooling capacity
of the chiller was determined by

Total cooling load
Total charging hours efficiency factor

Nominal cooling capacity ¼

ð
þ Total discharging hours efficiency factor Þ
ð 7 Þ

Therefore, nominal cooing capacity of the chiller

¼ 6 ; 186 = 14 0 : 9 ð f ð Þ þ 10 0 : 8 ð Þ g Þ ¼ 306 kW

Here, the efficiency factor for charging and discharging periods is assumed to
be 0.9 and 0.8, respectively.
Cooling capacity of chiller during direct cooling (on-peak load conditions)

¼ 306 0 : 9 ¼ 276 kW

Cooling capacity of chiller during charging of the TES system (part-load
conditions)

¼ 306 0 : 8 ¼ 245 kW

Cooling capacity shared by the TES system (energy redistribution) during on-
peak condition is determined as follows:
At the start of the part-load condition (typically at 19 h):

Cooling capacity of TES ¼ Cooling capacity of chiller at the specific hour of part load condition ð

Total cooling load at that hour Þþ Storage balance at the previous hour
ð 8 Þ

Thus, the cooling capacity of TES ¼ 245 170 ð Þ þ 0 ¼ 75 kW