Question

The contents of a reaction vessel are heated by means of steam at 393 K supplied to a heating coil which is totally immersed in the liquid. When the vessel has a layer of lagging 50 mm thick on its outer surfaces, it takes one hour to heat the liquid from 293 to 373 K . How long will it take if the thickness of lagging is doubled? Outside temperature $=293 \mathrm{~K}$. Thermal conductivity of lagging $=0.05 \mathrm{~W} / \mathrm{mK}$. Coefficient for heat loss by radiation and convection from outside surface of vessel $=10 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$. Outside area of vessel $=8 \mathrm{~m}^2$. Coil area $=0.2 \mathrm{~m}^2$. Overall heat transfer coefficient for steam coil $=300 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$.

   The contents of a reaction vessel are heated by means of steam at 393 K supplied to a heating coil which is totally immersed in the liquid. When the vessel has a layer of lagging 50 mm thick on its outer surfaces, it takes one hour to heat the liquid from 293 to 373 K . How long will it take if the thickness of lagging is doubled? Outside temperature $=293 \mathrm{~K}$. Thermal conductivity of lagging $=0.05 \mathrm{~W} / \mathrm{mK}$. Coefficient for heat loss by radiation and convection from outside surface of vessel $=10 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$. Outside area of vessel $=8 \mathrm{~m}^2$. Coil area $=0.2 \mathrm{~m}^2$. Overall heat transfer coefficient for steam coil $=300 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$.

Chemical Engineering. Solutions to the Problems in Chemical Engineering

Richardson J.F.,… 1st Edition

Chapter 9, Problem 65

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Step 1

05 m). The heat transfer through the lagging can be calculated using Fourier's law of heat conduction: \[ Q = \frac{k \cdot A \cdot (T_{steam} - T_{outer})}{d} \] Where: - $ k = 0.05 \, \text{W/mK} $ (thermal conductivity of lagging) - $ A = 8 \, \text{m}^2 $ Show more…

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The contents of a reaction vessel are heated by means of steam at 393 K supplied to a heating coil which is totally immersed in the liquid. When the vessel has a layer of lagging 50 mm thick on its outer surfaces, it takes one hour to heat the liquid from 293 to 373 K . How long will it take if the thickness of lagging is doubled? Outside temperature $=293 \mathrm{~K}$. Thermal conductivity of lagging $=0.05 \mathrm{~W} / \mathrm{mK}$. Coefficient for heat loss by radiation and convection from outside surface of vessel $=10 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$. Outside area of vessel $=8 \mathrm{~m}^2$. Coil area $=0.2 \mathrm{~m}^2$. Overall heat transfer coefficient for steam coil $=300 \mathrm{~W} / \mathrm{m}^2 \mathrm{~K}$.

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