A spacecraft component is cooled by a stirred tank of water, which is in turn cooled by radiant heat transfer to space. The water is at a constant temperature of 90C. The tank wall is 20mm thick, and the temperature of its inner surface (T1) is a constant 80C. The structure of the system is shown in Figure 1: Figure 1 Relevant constants: Inner surface convective heat transfer coefficient: 78 W.m-2.K-2 Conductive heat transfer coefficient of wall: 4 W.m-1.K-1 Emissivity of wall outer surface: 0.95 Stefan-Boltzmann constant: 5.67x10-8 W.m-2.K-4 Assuming that the system is one-dimensional and at steady state, (a) Draw a thermal circuit diagram for the system. (2 marks) (b) If the total wall area is 1m2, calculate the rate of heat transfer from the water to the inner wall. (2 marks) (c) Calculate the temperature T2 of the outer surface of the wall. (2 marks) (d) You might expect the temperature of space to be absolute zero, but this is not the case. Even in the shade there is some radiation incident on the surface of a spacecraft, and thus space has an effective temperature. Calculate this effective temperature in the vicinity of our spacecraft. Be very careful with your temperature units! (2 marks)