Welcome to Westonci.ca, where finding answers to your questions is made simple by our community of experts. Experience the ease of finding precise answers to your questions from a knowledgeable community of experts. Explore comprehensive solutions to your questions from a wide range of professionals on our user-friendly platform.
Sagot :
Answer:
31.282 psia
Explanation:
Calculate the mean effective pressure of an ideal Otto cycle
Given data:
compression ratio = 9
inlet pressure ( P1 ) = 14 psia
Initial temperature ( T1 ) = 60°F = 520 R
Final/maximum temp ( T3 ) = 1500°F = 1960 R
using the constant specific heats at room temperature
attached below is the detailed solution
The mean effective pressure of the ideal Otto Cycle that uses air as the working fluid is; 31.28 psia
We are given;
Initial pressure; P₁ = 14 psia
Initial temperature; T₁ = 60°F = 520 R
Maximum temperature; T₃ = 1500°F = 1960 R
Compression ratio = 9
From tables, the specific heat capacities and constants are;
c_v = 0.171 btu/lbm.R
c_p = 0.24 btu/lbm.R
R = 0.3704 btu/lbm.R
ratio of specific heats; k = 1.4
Let us first calculate the initial volume from the formula;
V₁ = RT₁/P₁
V₁ = (0.3704 * 520)/14
V₁ = 13.7577 ft³/lb.m
- Compression ratio is; V₁/V₂ = 9
Thus;
V₂ = V₁/9
V₂ = 13.7577/9
V₂ = 1.5286 ft³/lb.m
- To get the temperature T₂, we will use the formula;
T₂ = T₁(V₁/V₂)^(k - 1)
T₂ = 520(9)^(1.4 - 1)
T₂ = 1252.277 R
Similarly;
T₄ = T₃/9
T₄ = 1960/(9^(1.4 - 1))
T₄ = 813.87 R
- Formula for heat entering and heat exiting are;
Q_in = c_v(T₃ - T₂)
Q_in = 0.171(1960 - 1252.277)
Q_in = 121.02 btu/lbm
Q_out = c_v(T₄ - T₁)
Q_out = 0.171(813.87 - 520)
Q_out = 50.251 btu/lbm
- Net work done is given by;
W_net = Q_in - Q_out
W_net = 121.02 - 50.251
W_net = 70.769 btu/lbm
Formula for the mean effective pressure is;
mean effective pressure = W_net/(V₁ - V₂)
mean effective pressure = 70.769/(13.7577 - 1.5286)
mean effective pressure = 5.7869 btu.ft³
Converting to psia gives;
Mean effective pressure = 31.28 psia
Read more about compression ratio at; https://brainly.com/question/16014998
We hope this information was helpful. Feel free to return anytime for more answers to your questions and concerns. We hope this was helpful. Please come back whenever you need more information or answers to your queries. We're dedicated to helping you find the answers you need at Westonci.ca. Don't hesitate to return for more.