PLEASE TYPE ANSWER AND EXPLINATION CLEARLY PICS ARE HARD TO

PLEASE TYPE ANSWER AND EXPLINATION CLEARLY (PICS ARE HARD TO READ)

Refrigerant enters an insulated throttle valve as a saturated liquid at pressure p1=8bar and exits at pressure p2=1.2bar. Kinetic and potential energy effects can be neglected. Determine:

a). the temperature and quality of the refrigerant at the exit

b) whether the throttling process is reversible of irreversible

Solution

>> Now, here, we are assuming that refrigerant is R134a

>> So, at P1 = 8 bar = 800 kPa , and as it is present as a saturated liquid.

So, seeing from property table of Refrigerant R134a, h1 = Enthalpy = 95.5 KJ/Kg

>> Now, during throttling, enthalpy remains constant.

So, h2 = h1 = 95.5 KJ/Kg

and as at P2 = 1.2 bar = 120 kPa

From Table, temperature = - 22.3 C

hf = 22.5 KJ/Kg,

hg = 237.0 KJ/Kg

>> Let Quality of refrigerant = x

So, h2 = 95.5 = hf + x*(hg - hf)

=> 95.5 = 22.5 + x*(214.5)

=> x = 0.34

So, at the exit, temperature = - 22.3 C & Quality of Refrigerant = 34 %

>> Part (b)

Throttling is an irreversible process. The throttling due to the flow resistance in supply lines, heat exchangers,

regenerators, and other components of (thermal) machines is a source of irreversibility.