Final Problems - users.encs.concordia.ca

PROPRIETARY MATERIAL. © 2008 The McGraw-Hill Companies, Inc. Limited distribution permitted only to teachers and educators for course preparation. If you are a student using this Manual, you are using it without permission.

14-55

kg/min 439.9kg/s 1573.00.85

kJ/kg )48.25490.286(kW 6

1,2

==

−=

−=

R

R

C

RsRRC

m

m

hhmW

&

&

&&η

The rate of heat absorbed by the R-134a in the evaporator is

kJ/min 1.1042kJ/kg )07.14448.254(kg/min) 439.9()( 41in, =−=−= RRRR hhmQ &&

The rate of heat lost from the air in the evaporator is absorbed by the refrigerant-134a. That is,

outin, QQR&& = . Then, the volume flow rate of the air at the inlet of the evaporator can be determined from

Eq. (1) to be

/minm 44.87 3=⎯→⎯++= 1111 (33.63)002646.0(23.11)

0.84741.1042(43.05)

0.8474VV

VV &&&