Complete the following table for R-134a using either the NIST Webbook or the Thermal/Fluids Toolbox (TFT) Excel plug-in.
T(oF) P(psia) U(Btu/lbm) x(lbm vap/lbm) Phase Description
a.) P = 80 psia, U = 126 Btu/lbm
b.) T = 15oF, x = 0.6 lbm vap/lbm
c.) T = 10oF, P = 70 psia
d.) P = 180 psia, U = 224 Btu/lbm
e.) T = 110oF, x = 1.0 lbm vap/lbm
3 comments:
A student asked me if there was a typo in my answers and there is not. The issue was that he did not use the DEFAULT reference state. If you want to have any hope of matching my answers when U or H are either given or asked for, we must choose the same reference state. For both NIST and the TFT, I used their respective DEFAULT reference states. You should too !
i am wondering if it means it is superheated vapor if I got some x great than 1. And I got 117.73 F for the d) temperature which is very different from the answer. I got the same problem for 1e) also.
QuestionGuy:
Yes. You probably ASSUMED the system contained a saturated mixture and it does not. If x turns out to be < 0 or > 1, the system does not contain a saturated mixture but contains a subcooled liquid if x < 0 and a superheated vapor if you get x >1.
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