QuestionIV (17 marks). (4) Determine the steady-state surface temperature of an electric cable, 25 cm in diameter, which is suspended horizontally in still air in which heat is dissipated by the cable at a rate of A W per meter of length. The air temperature is BC. Since the cable has a length much greater than its diameter, you can consider a 1-D heat transfer in the radial direction of the cable. The corresponding heat transfer coefficient (or Nusselt number) for a horizontal cylinder can be estimated by the Churchill and Chu correlation, 0.387Ra D6 NUD = 0.6 + 9 27 0.559 16 {1+( Pr 2 The properties of air may be estimated based on interpolation of the following data: T(K) 300 320 K (W/m.K) 2.62E-02 2.78E-02 Pr gp/ 0.708 1.33E+08 0.703 9.94E+07 (0) A 27, B = 30 (1) A = 27, B = 27. (2) A = 27, B = 25. (3) A = 27, B = 22. (4) A = 27, B = 20. (5) A 30, B = 30. (6) A = 30, B = 27. (7) A = 30, B = 25. (8) A = 30, B = 22. (9) A = 30, B = 20. Recommended initial guess for the above parameter sets is given by (0) 313.4K (1) 310.3K. (2) 308.3K. (3) 305.3K. (4) 303.3K. (5) 314.2K. (6) 311.2K. (7) 309.2K. (8) 306.1K. (9) 304.1K. Yourparametervalue for (A,B) will be based on the last digit of your studentnumber e.g. If yourmetriccardnumberis A0185796Y, please takethe (A,B) value fromparameter set (6) below. A similarrule is applied to other cases.