The temperature in oC at the inner surface of the pipe at the outlet is

Question

Common Data for Question 1 & 2

Water (specific heat, c_p = 4.18 kJ/kgK) enters a pipe at a rate of 0.01 kg/s and temperature of 20⁰C. The pipe, of diameter 50 mm and length 3m, is subjected to a wall heat flux q_w in W/m².

 

1. If q_w = 2500x, where  x is m and in the direction of flow (x=0 at the inlet), the bulk mean temperature of the water leaving the pipe in ⁰C is                                                                 

      (a) 42                              (b) 62                           (c) 74                              (d) 104

 

2 . If q_w = 5000 and the convection heat transfer coefficient at the pipe outlet is 1000 W/m²K, the temperature in ⁰C at the inner surface of the pipe at the outlet is                                                                                              

      (a) 71                              (b) 76                           (c) 79                              (d) 81