A counterfl ow plate heat exchanger is being used to heat apple juice with Example 4.21

hot water. The heat exchanger contains 51 plates. Each plate is 1.2 m high

and 0.8 m wide. The gap between the plates is 4 mm. The heating characteristics for this heat exchanger have been previously determined to follow

the following relationship, N NN Nu Re0.64 Pr

0.4 0.4 . Hot water enters the heat

exchanger at 95°C at a rate of 15 kg/s and apple juice enters at 15°C at a rate

of 10 kg/s. It is assumed that the physical properties of water and apple juice

are the same. The properties of water at 55°C are density 985.7 kg/m 3

,

specifi c heat 4179 J/kgK, thermal conductivity 0.652 W/m°C, dynamic

viscosity 509.946 10 6

Ns/m 2

, Prandtl Number 3.27. Calculate the exit

temperatures of water and apple juice.

# A counterfl ow plate heat exchanger is being used to heat apple juice with Example 4.21 hot water. The heat exchanger contains 51 plates. Each plate is 1.2 m high and 0.8 m wide. The gap between the plates is 4 mm. The heating characteristics for this heat exchanger have been previously determined to follow the following relationship, N NN Nu Re0.64 Pr 0.4 0.4 . Hot water enters the heat exchanger at 95°C at a rate of 15 kg/s and apple juice enters at 15°C at a rate of 10 kg/s. It is assumed that the physical properties of water and apple juice are the same. The properties of water at 55°C are density 985.7 kg/m 3 , specifi c heat 4179 J/kgK, thermal conductivity 0.652 W/m°C, dynamic viscosity 509.946 10 6 Ns/m 2 , Prandtl Number 3.27. Calculate the exit temperatures of water and apple juice.

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