C

2O.58 x 1O6 Btus

Volume of Water = Mass/Density =

average suggested in the EPRI report7 This will increase the storage requirements to 2,144 Ton-Hrs. Assuming that there are 12,000 Btu's per Ton-Hr, this yields: (2,144 Ton-Hrs)*(12,000 Btu's/Ton-Hr) = 25.73 x 106 Btu's. The ice systems utilize the latent heat of fusion so the C1 now becomes

Because the latent heat of fusion, which occurs at 32°F, is so large compared to the sensible heat, the sensible heat (Cp) is not included in the calculation. The mass of water required to be frozen becomes:

Mass

Volume of Ice =

Density = 2,864 Ft3

1.79 x 1O5 lbm t62t.5tlbtm/tFtt3

Sizing the storage system utilizing ice is completed in a very similar fashion. The EPRI study states that the ice storage tanks had average daily heat gains 3.5 times greater than the chilled water and eutectic systems due to the higher coil temperature differential (T2-T1) To allow for these heat gains a conservative value of 50% will be added to the actual storage capacity, which is an

This figure is conservative since the sensible heat has been ignored but calculates the volume of ice needed to be generated. The actual volume of ice needed will vary and the total amount of water contained in the tank around the ice coils will vary greatly. The ability to purchase pre-packaged ice storage systems makes their sizing quite easy For this situation, two 1,080 Ton-Hr ice storage units will be purchased for approximately $150/

Table 19.9 Complete system comparison.
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