Additional question: A4-5 Consider a long cylindrical pipe with length and outer radius r1. The outer surface temperature of the pipe, T1, is maintained constant. The pipe is insulated with a material of thermal conductivity k such that the outer radius of the insulation is r2. The surrounding air is at a constant temperature T, and the convection heat transfer coefficient between the outer surface of insulation and the air is h. a) Derive an expression for the one-dimensional, radial heat transfer Q between the outer surface of the pipe and the surrounding air. You may express your answer in terms of the following parameters: ,r1,r2,T1,T,k, and h. [5 marks] b) The variation of Q with the outer radius of insulation r2 is shown below. With all other parameters held constant, solve for the critical value of r2 at which Q reaches its maximum value. You may express your answer using as many of the parameters from part (a) as required. [5 marks] Draw a box around your final answer for each question so that it is clearly identified. 347, use k=60.5W/(mK) for the thermal conductivity of steel and k=0.058W/(mK) for the thermal conductivity of acoustic tile. To simplify the analysis, consider one 10cm10cm 'unit' of the wall, as shown below. [10 marks] Additional question: A4-5 Consider a long cylindrical pibe with length and outer radius r1. The outer surface