8/17/2019 Ejercicios 2 Para Alumnos

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1. One kg of air at 100 kPa is mixed with one kg air at 200 kPa, both at 300

K, in a rigid insulated tank. Find the nal state P, !" and the entro#$

generation in the #ro%ess.

2. & window re%ei'es 200 ( of heat transfer at the inside surfa%e of 20o)and transmits the 200 ( from its outside surfa%e at 2o) %ontinuing to

ambient air at *+o). Find the ux of entro#$ at all three surfa%es and the

window-s rate of entro#$ generation.

3. & rigid storage tank of 1.+ m3 %ontains 1 kg argon at 30). /eat is then

transferred to the argon from a furna%e o#erating at 1300) until the

s#e%i% entro#$ of the argon has in%reased b$ 0.33 kkg K. Find the

total heat transfer and the entro#$ generated in the #ro%ess.

. & 2kgs ow of steam at 1 4Pa, 500) should be brought to +00) b$

s#ra$ing in li6uid water at 1 4Pa, 20) in an stead$ ow. Find the rate of

irre'ersibilit$, assuming that surroundings are at 20).

+. & heat engine o#erating with an e'ironment at 278 K #rodu%es + k( of

#ower out#ut with a rst law e9%ien%$ of +0:. ;t has a se%ond law

e9%ien%$ of 80: and !< = 310 K. Find all the energ$ and exerg$ transfers

in and out.

>. ?'aluate the stead$ state exerg$ uxes due to a heat transfer of 2+0 (

through a wall with >00 K on one side and 00 K on the other side. (hat

is the exerg$ destru%tion in the wall.