5.4 A particular power plant operates with a heat-sources reservoir at 350oC and a heat-sink reservoir at 30oC. It has a thermal efficiency equal to 55% of the Carnot-engine thermal efficiency for the same temperature.a) What is the thermal efficiency of the plant?b) To what temperature must the heat-sources reservoir be raised to increase the thermal efficiency of the plant to 35%? Again is 55% of theη Carnot-engine value.

Penyelesaian

Diketahui :

T cold = 30oC = 30 + 273,15 = 303,15 KT heat = 350oC = 350 + 273,15 = 623,15 K

Ditanya :

a) ηb) T heat ( = 35%)η

Jawab :

a) carnot η =

=

carnot η = 0,5135

η = 55% = 0,55

η = 0,55 x carnotηη = 0,55 x 0,5135η = 0,2824

b) η = 35% = 0,35

0,35 = 0,55 x carnotη

carnotη =

carnotη = 0,6363

carnot η =

T heat =

=

T heat = 833,52 K