Heat Transfer: Example Problems Upd

Now heat flux: [ q = \frac{1100 - 50}{0.8334} = \frac{1050}{0.8334} \approx 1260 , \text{W/m}^2 ]

[ \frac{T(t) - T_\infty}{T_i - T_\infty} = \exp\left(-\frac{h A_s}{\rho V c_p} t\right) ] For a sphere: ( A_s/V = 6/D ). [ \frac{100 - 25}{200 - 25} = \exp\left(-\frac{20 \cdot 6}{8933 \cdot 0.02 \cdot 385} t\right) ] [ \frac{75}{175} = 0.4286 = \exp(-0.001744 \cdot t) ] [ \ln(0.4286) = -0.8473 = -0.001744 , t ] [ t \approx 486 , \text{seconds} , (\approx 8.1 , \text{minutes}) ] heat transfer example problems

[ R_{cond} = \frac{\ln(0.06/0.05)}{2\pi \cdot 15} = \frac{\ln(1.2)}{94.2478} = \frac{0.1823}{94.2478} = 0.001934 , \text{m·K/W} ] Now heat flux: [ q = \frac{1100 - 50}{0

Try modifying the numbers: add a contact resistance, change the emissivity, or switch to a different fluid. That’s where the real learning happens. t ] [ t \approx 486