Liquid water (cp = 4217 J/kg K, k = 0.679 W/mK, μ = 0.282×10…
Liquid water (cp = 4217 J/kg K, k = 0.679 W/mK, μ = 0.282×10-3 Pa-s) enters a 3 m long horizontal circular copper tube of 2.5 cm inner diameter and negligible thickness. The water inlet temperature is 40°C and flows at a mass flow rate of 0.0036 kg/s. The tube surface is subjected to a constant heat flux of 1.8 kW. The goal is to determine whether the tube’s surface temperature exceeds the maximum allowable value of 204°C, as specified by the ASME Code for Process Piping. (a) Based on the flow conditions, assess whether the flow is thermally and hydrodynamically fully developed or still in the developing region at the outlet of the pipe. Typically, less or around 30% of the total length in the developing region is acceptable. (b) Calculate the average convective heat transfer coefficient of the fluid. (c) Determine the surface temperature at the exit of the tube, assuming a constant surface heat flux. (d) Find the axial position along the tube where the surface temperature first reaches the critical value of 204°C. Hint: To find the axial location where the tube’s surface temperature reaches 204°C, begin by determining the mean temperature of the fluid at that location.
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