Hot water enters a double-pipe counter-flow water-to-oil heat exchanger at 220°7 and leaves a 100°f. oil enters at 70°f and leaves at 150°f. determine which fluid has the smaller heat capacity rate and calculate the effectiveness of this heat exchanger.

Oil has the smaller heat capacity. The effectiveness of the heat exchanger is 0.80.

Explanation:

Part 1:

In order to know which fluid has the smaller heat capacity we need to consider the heat equation below:

Q = CΔT, where Q is the heat exchanged, C is the heat capacity and ΔT is the variation in temperature.

As the heat exchange is the same for both fluids, the smaller the temperature variation, the smaller the heat capacity.

Water: ΔT = 120 °F  

Oil: ΔT = 80 °F  

Therefore, oil is the fluid with the smallest heat capacity.

Part 2:

The effectiveness of a counter-flow heat exchanger is given by the equation bellow:

Th1: initial temperature of the hot fluid

Th2: final temperature of the hot

Tc1: initial temperature of the cold fluid

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

you did not give any options thus this is the best answer i can give to you with this little information you have given

> they are both natural and not man made

> they can be tracked and predicted by the right tools

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