Peas are being blanched by immersing them in hot water at 85°C until the centre of the pea reaches 70°C.
The average pea diameter is 0.0048 m and the thermal properties of the peas are: thermal conductivity 0.48 J
m-1 s-1 °C-1,specific heat 3.51 x 103 J kg-1 °C-1 and density 990 kg m-3. The surface heat-transfer coefficient
to the peas has been estimated to be 400 J m-2 s-1 °C-1. (a) How long should it take the average pea to
reach 70°C if its initial temperature was 18°C just prior to immersion? (b) If the diameter of the largest pea is
0.0063 m, what temperature will its centre have reached when that of the average pea is 70°C?