Question

(5-95) Argon steadily flows into a constant pressure heater at 300 K and 100 kPa with a mass flow rate of 6.24 kg/s Heat transfer in the rate of 150 kW is supplied to the argon as it flows through the heater. (a) Determine the argon temperature at the heater exit, in ℃. (b) Determine the argon volume flow rate at the heater exit, in m3/s.

Answer 1

Answer:

a) 346.22 K

b) 4.49 m³/s

Explanation:

P₁ = P₂ = Pressure in heater = 100 kPa

T₁ = Initial temperature = 300 K

m = Mass flow rate = 6.24 kg/s

Q = Heat transfer rate = 150 kW

Cp = Specific heat at constant pressure of argon = 0.520 kJ/kg K

R = Gas constant of argon = 0.2082 kJ/kg K

a) $Q = mC_p\Delta T\\\Rightarrow 150=6.24\times 0.52\times (T_2-300)\\\Rightarrow \frac{150}{6.24\times 0.52}= T_2-300\\\Rightarrow T_2=346.22 K$

∴ The argon temperature at the heater exit is 346.22 Kelvin

b) $P_2V_2=mRT_2\\\Rightarrow V_2=\frac{mRT_2}{P_2}\\\Rightarrow V_2=\frac{6.24\times 0.2082\times 346.22}{100}\\\Rightarrow V_2=4.49\ m^3/s$

∴ Argon volume flow rate at the heater exit 4.49 m³/s