A gas initially at 1.5 bar pressure, 0.15m

3

volume and 300 K was compressed

polytropically (pv 1.25 = constant) to 15 bar pressure. Determine the change

in entropy. Also work out the approximate entropy change obtained by

dividing the heat transferred by the mean absolute temperature during compression.

Take cp = 1.04 kJ / kg K and cv = 0.745 kJ / kg K.

Line joining liquid phase with liquid and solid phase mixture is known as: a) liquidus b) solidus c) tie line d) none of the mentioned

Give heat transfer applications for the following, (i) gas turbines (propulsion) ) gas turbines (power generation). (iii) steam turbines. (iv) combined heat and power (chp). (v) automotive engines

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk