Ammonia enters the expansion valve of a refrigeration system at a pressure of 1.4 MPa and a temperature of 32degreeC and exits a
t 0.08 MPa. If the refrigerant undergoes a throttling process, what is the quality of the refrigerant exiting the expansion valve?
1 answer:
Answer:
the quality of the refrigerant exiting the expansion valve is 0.2337 = 23.37 %
Explanation:
given data
pressure p1 = 1.4 MPa = 14 bar
temperature t1 = 32°C
exit pressure = 0.08 MPa = 0.8 bar
to find out
the quality of the refrigerant exiting the expansion valve
solution
we know here refrigerant undergoes at throtting process so
h1 = h2
so by table A 14 at p1 = 14 bar
t1 ≤ Tsat
so we use equation here that is
h1 = hf(t1) = 332.17 kJ/kg
this value we get from table A13
so as h1 = h2
h1 = h(f2) + x(2) * h(fg2)
so
exit quality =
exit quality =
so exit quality = 0.2337 = 23.37 %
the quality of the refrigerant exiting the expansion valve is 0.2337 = 23.37 %
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Answer:
the endurance strength = 421.24 MPa
Explanation:
From the given information; The objective is to estimate the endurance strength, Se, in MPa .
To do that; let's for see the expression that shows the relationship between the ultimate tensile strength and Brinell hardness number .
It is expressed as:
where;
= Brinell hardness number
= Ultimate tensile strength
From ;
; replace 290 for
; we have
988.9 MPa
We can see that the derived value for the ultimate tensile strength when the Brinell harness number = 290 is less than 1400 MPa ( i.e it is 988.9 MPa)
So; we can say
The Endurance limit can be represented by the formula:
= 494.45 MPa
Using Table 6.2 for parameter for Marin Surface modification factor. The value for a and b are derived; which are :
a = 1.58
b = -0.085
The value of the surface factor can be calculate by using the equation
The formula that is used to determine the value of for the rotating shaft of size factor d = 10 mm is as follows:
Finally; the the endurance strength, Se, in MPa if the rod is used in rotating bending is determined by using the expression;
= 0.8792×0.969×494.45
= 421.24 MPa
Thus; the endurance strength = 421.24 MPa