Question

A chemical industry produces 200 tons of sulfuric acid per day when running at 24 hours. The acid is cooled in a counter flow double pipe heat exchanger from 60 0C to 40 0C. The cooling medium employed is water, which enters the heat exchanger at 15 0C and leaves at 20 0C. The acid flows through the inner pipe, while water flows through the annulus. The inner and outer diameters of the inner pipe are 70 mm and 80 mm, respectively, while that of outer pipe are 120 mm and 130 mm, respectively. The thermal conductivity of the inner pipe is 46.5 W/m-K. Use Dittus-Boelter’s equation for the estimation of heat transfer coefficients. Calculate the (a) mass flow rate of water in kg/h. (b) length of the heat exchanger. The properties of water at mean bulk temperature are: ρ = 998.2 kg/m3, Cp = 4.18 kJ/kg-K, k = 0.598 W/m-K and υ = 1.006 × 10-6 m2/s. The properties of acid at mean bulk temperature are: ρ = 1800 kg/m3, Cp = 1.465 kJ/kg-K, k = 0.302 W/m-K and υ = 6.8 × 10-6 m2/s.

Answer 1

using given data and dietus boltier equation we can find the length and mass flow

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