Question

Water at 80∘C flows through a 50 mm bore steel pipe of 6 mm thickness, and the atmospheric temperature is 15∘C. The thermal conductivity of steel is 48 W/mK and the inside and outside heat transfer coefficients are 2800 and 17 W/m2 K respectively. Neglecting radiation, calculate the rate of heat loss per unit length of pipe.

Answer 1

To calculate the rate of heat loss per unit length of the pipe, we need to consider both the heat conduction through the steel pipe and the convective heat transfer between the inside and outside of the pipe and the surrounding atmosphere.

To calculate the rate of heat loss per unit length of the pipe, we need to consider both the heat conduction through the steel pipe and the convective heat transfer between the inside and outside of the pipe and the surrounding atmosphere. The rate of heat conduction through the steel pipe can be calculated using Fourier's Law:

Q_conduction = k * A * (T_inside - T_outside) / d

where Q_conduction is the rate of heat conduction, k is the thermal conductivity of steel, A is the cross-sectional area of the pipe, T_inside is the temperature inside the pipe, T_outside is the temperature outside the pipe, and d is the thickness of the pipe. The rate of heat transfer due to convection can be calculated using the heat transfer coefficient:

Q_conv = h * A * (T_inside - T_ambient)

where Q_conv is the rate of heat transfer due to convection, h is the inside heat transfer coefficient, T_ambient is the atmospheric temperature, and A is the cross-sectional area of the pipe.

By substituting the given values into these equations, we can calculate the rate of heat loss per unit length of the pipe.