TM-5-855-4
b. A full reservoir of volume V at temperature T0 with allowable wasted water discharge temperature
T1 represents a total cooling capacity qo which, when spent at constant heat rejection rate qo until empty,
will allow to hours of operation. Any one of these parameters may be computed from the following heat
balances when the others are known:
c. If the water is recirculated from the reservoir to the engine jacket or condenser and back to the
reservoir, the heat-absorbing capacity of the water is increased by the heat-absorbing capacity of the
surrounding rock because the warmer water returning from the equipment increases the reservoir's
temperature above that of the rock.
(1) To obtain the best effect from a reservoir used as a short-time heat sink, water will be taken
from the lowest point in the reservoir and heated water discharged to the highest point. The warmest
water will stratify in the upper levels, while the water taken from the bottom will be the coldest available
for cooling purposes.
(2) When the water temperature reaches its maximum allowable temperature, the water of the
reservoir is wasted outside the installation. The time to waste the water can be determined using
equation 5-1.
(3) During the initial period when the effective capacity is enhanced by heat transfer to the rock,
empirical equation 5-2 is used for the reservoir of length L, allowed to heat from T2 to T3 in a specified
time tl. The reservoir's constant effective heat absorption rate ql in Btuh during this period is then
5-2
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