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| author | priyanka | 2015-06-24 15:03:17 +0530 |
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| committer | priyanka | 2015-06-24 15:03:17 +0530 |
| commit | b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b (patch) | |
| tree | ab291cffc65280e58ac82470ba63fbcca7805165 /572/CH9/EX9.3/c9_3.sce | |
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diff --git a/572/CH9/EX9.3/c9_3.sce b/572/CH9/EX9.3/c9_3.sce new file mode 100755 index 000000000..3046be53b --- /dev/null +++ b/572/CH9/EX9.3/c9_3.sce @@ -0,0 +1,52 @@ +//(9.3) At the beginning of the compression process of an air-standard dual cycle with a compression ratio of 18, the temperature is 300 K and the pressure is 0.1 MPa. The pressure ratio for the constant volume part of the heating process is 1.5:1. The volume ratio for the constant pressure part of the heating process is 1.2:1. Determine (a) the thermal efficiency and (b) the mean effective pressure, in MPa.
+
+
+//solution
+
+//variable initialization
+T1 = 300 //beginning temperature in kelvin
+p1 = .1 //beginning pressure in MPa
+r = 18 //compression ratio
+pr = 1.5 //The pressure ratio for the constant volume part of the heating process
+vr = 1.2 // The volume ratio for the constant pressure part of the heating process
+
+//analysis
+//States 1 and 2 are the same as in Example 9.2, so
+u1 = 214.07 //in kj/kg
+T2 = 898.3 //in kelvin
+u2 = 673.2 //in kj/kg
+//Since Process 2–3 occurs at constant volume, the ideal gas equation of state reduces to give
+T3 = pr*T2 //in kelvin
+//Interpolating in Table A-22, we get
+h3 = 1452.6 //in kj/kg
+u3 = 1065.8 //in kj/kg
+//Since Process 3–4 occurs at constant pressure, the ideal gas equation of state reduces to give
+T4 = vr*T3 //in kelvin
+//From Table A-22,
+h4 = 1778.3 //in kj/kg
+vr4 = 5.609
+//Process 4–5 is an isentropic expansion, so
+vr5 = vr4*r/vr
+//Interpolating in Table A-22, we get
+u5 = 475.96 //in kj/kg
+
+//part(a)
+eta = 1-(u5-u1)/((u3-u2)+(h4-h3))
+printf('the thermal efficiency is: %f',eta)
+
+//part(b)
+//The specific volume at state 1 is evaluated in Example 9.2 as
+v1 = .861 //in m^3/kg
+mep = (((u3-u2)+(h4-h3)-(u5-u1))/(v1*(1-1/r)))*10^3*10^-6 //in MPa
+printf('\nthe mean effective pressure, in MPa is: %f',mep)
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