Examine a process whereby air at 300 K, 100 kPa is compressed in a piston/cylinder arrangement to 600 kPa. Assume the process is
polytropic with exponent equal to 1.2 or 1.6. Find the work and heat transfer per unit mass of air in each case. Discuss the two cases and how they may be accomplished by insulating the cylinder or by providing heating or cooling.
1 answer:
Answer:
See attachment and explanation.
Explanation:
- The following question can be solved better with the help of a MATLAB program as follows. The code is given in the attachment.
- The plot of the graph is given in attachment.
- The code covers the entire spectrum of the poly-tropic range ( 1.2 - 1.6 ) and 20 steps ( cases ) have been plotted and compared in the attached plot.
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Answer:
Explanation:
Hello,
a. On the attached document, you can see a brief scheme of the process. Thus, to know the degrees of freedom, we state the following unknowns:
- and
: extent of the reactions (2).
- ,
,
,
and
: Molar flows at the second stream (5).
On the other hand, we've got the following equations:
- : oxygen mole balance.
- : methane mole balance.
- : water mole balance.
- : formaldehyde mole balance.
- : carbon dioxide mole balance.
Thus, the degrees of freedom are:
It means that we need two additional equations or data to solve the problem.
b. Here, the two missing data are given. For the fractional conversion of methane, we define:
And for the fractional yield of formaldehyde we can set it in terms of methane as the reagents are equimolar:
In such a way, one realizes that the output formaldehyde's molar flow is:
Which is equal to the first reaction extent , therefore, one computes the second one from the fractional conversion of methane as:
Now, one computes the rest of the output flows via:
-
-
-
-
-
The total output molar flow is:
Therefore the output stream composition turns out into:
Best regards.
