Coolant

Oil

ho

h

Hints:

A51m long concentric-tube counter-flow heat exchanger is used to cool lubricating oil. The oil

flows through the inner tube (diameter D, 60mm) with a mass flow rate of 0.22kg/s, while

the coolant flows through the outer annulus at 0.20kg/s.

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The oil enters the heat exchanger at 106°C and leaves at 53°C; while the colant enters at 26

°C.

The convection coefficient on the inside of the inner tube is h-300W/m²K.

Assume negligible fouling factors, that the inner tube is thin-walled, the heat exchanger is

adiabatic and is at steady state.

Use constant properties for the oil C -1.8kJ/kgK and coolant Ce=4.1kJ/kgK, and

assume that both oil and coolant flows are fully developed.

Determine the convection coefficient h, (W/m²K) on the coolant side of the inner tube.

Hint: Find the overall heat transfer coefficient U, then from there you can find ho

Give your answer to zero decimal places.

This is a concentric tube heat exchanger, and you can determine all of the temperatures

(you can find Teo using the energy equation), so you can use the LMTD method.

Make sure that your units are consistent. The units for specific heats should be consiste

with the convection coefficients.