847

Charge

Without storage With storage

Daily Total (Ton-Hrs): 6123 6123

Daily Total (Ton-Hrs): 6123 6123

Peak Total (Ton-Hrs): 3420 1225 Storage Total = 2195

Peak Demand (Tons): 510 153 Peak Storage Output = 357

Column 4 = Column 3 - Column 2 Column 5(n) = Column 5(n-1) + Column 4(n)

volume or size of the storage system for the partial load system for each of the different storage mediums. The design of the chiller and thermal storage system must provide enough chilled water to the system to satisfy the peak load, so particular attention should be paid to the pumping and piping. Table 19.9 summarizes the size requirement of each of the three different storage options.

To calculate the capacity of the partial load storage system, the relationship between capacity (C), mass (M), specific heat of material (Cp), and the coil temperature differential (T2-T1) shown in Figure 19.5a will be used:

The partial load system required that 1,429 Ton-Hrs be stored to supplement the output of the chiller during on-peak periods. This value does not allow for any thermal loss which normally occurs. For this discussion, a conservative value of 20% is used, which is an average suggested in the EPRI report7. This will increase the storage

Table 19.8 System performance comparison.
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