# Heat energy needed to raise water temperature from 50 degrees F to 212 degrees F?

100 gallons per minute flow of water at 50 degrees F passes through a theoretically 100% efficient heat exchanger. The hot side or energy to the heat exchanger is a 510 degree F hot gas (essentially steam).

Assuming the 510 degree hot gas will heat the water, what is the energy in BTU's needed to accomplish and what would the hot gas flow rate at 510 degrees need to be to perform this heating?

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#### Solution Preview

The heat exchange in the 100% efficient unit is:

Qwater = Qgas

(mcdeltaT)water = (mcdeltaT)gas

Thus we can calculate the heat needed to transfer to the water:

Qwater = mcdeltaT

m = 100 gpm = 833 (lb/min)

c = 1 Btu/lb.F

deltaT = 212 - 50 = 162 ...

#### Solution Summary

The heat energy required to turn liquid water in to steam is calculated. The energy in BTU's needed to accomplish and what would the hot gas flow rate at 510 degrees need to be to perform this heating is examined.