Question

a rigid container of 1.348-m3 is filled by r-134a of mass 10 kg at an initial temperature of -40°c. the container is then heated until the pressure is 200 kpa. determine the final temperature and the initial pressure.

Answer 1

See the attachment and refer table for answer in your book.

Answer 2

Answer:  90°

The given is a constant specific volume process. The specific volume is given by,

Given: m = 10kg, v = 1.348 m3  

$v_1 = v_2$ = V/m =  1.348/10 = 0.1348 $m^3/kg$

from the table, $V_f=.0007055 m^3/kg\quad and\quad V_g=.3569 m^3/kg$ for R134a

hence the given obtained specific volume is between V_f and V_g. Hence it is saturated. Hence the initial pressure will be 0.5164 bar which is equal to 51.62 kpa.

From the superheated table of R134a, by interpolation, if we check at pressure 200kpa or 2 bar, for specific volume 0.145 (which is nearer to obtained specific volume 0.1348), the temperature is 90 degrees.  

Hence, initial pressure = 51.62 kpa and final temperature = 90 degrees.