Consider a very long straight hot cylinder that is allowed to cool in a cold environment, whose natural convection is characterised by a constant heat-transfer convection coefficient. a) Explain what Te and T. indicate in the chart of Figure Q2. b) Clearly explain how to use the chart to find the time that it takes for the centre line of the cylinder to reach a specified temperature, once one knows the cylinder radius, the initial temperature of the cylinder, the temperature of the environment, the convection coefficient, the thermal conductivity and diffusivity of the material of the cylinder.

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