Water at a local bulk temperature of 24°C flows at 0.8 m/sthrough a smooth, 1.5-cm-ID tube that is kept at 30°C and the flowis fully developed.
a) The system is extremely clean and quiet; therefore, the flowstays laminar regardless of the magnitude of ReD, until a noisy aircompressor is turned on in the laboratory. Then the flow suddenlygoes turbulent. Calculate the ratio of turbulent to laminar heattransfer coefficients. Use the Gnielinski correlation for turbulentflow.
b) Air at 227°C flows across the pipe at 20 m/s. Find the pipewall temperature assuming the water flow to be turbulent, h frompart a). You may assume a thin-walled pipe. This calculation isperformed at the local point where the bulk temperature is24°C.
