Diesel Engine Prob: Formula for Temp at Stages 3 & 4

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SUMMARY

The discussion focuses on calculating the temperatures at stages 3 and 4 of a Diesel engine's air standard cycle. The formula for temperature at stage 3 (T3) is defined as T3 = T2 + (Q1 / (m * cp)), where Q1 is the heat input, T2 is the temperature at stage 2, m is the mass, and cp is the specific heat at constant pressure. For stage 4 (T4), the formula is T4 = T3 * (V3/V4) ^ (k-1), where V3 and V4 are the volumes at stages 3 and 4, respectively, and k is the adiabatic constant of air. These formulas are essential for understanding the thermal dynamics of Diesel engines.

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  • Understanding of thermodynamic cycles, specifically the air standard cycle.
  • Familiarity with the concepts of specific heat and adiabatic processes.
  • Knowledge of the Diesel engine's operational principles.
  • Basic mathematical skills for manipulating formulas and solving equations.
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waterboy312
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how would you find the correct formula for the temp at state 3 and 4. i found it for 1 and 2
 
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Hello Waterboy.

First, I would ask that when you have a question try to be specific and do not abbreviate the words, because many members here are from different countries and areas.

For an air standard cycle, whose fuel is Diesel:

To calculate the temperature in the cycle expansion (3), it will be the point of greatest pressure and higher temperature, use the formula:


T3 = T2 + (Q1 / (m * cp);

where:

Q1 = heat input
T2 = temperature cycle 2
m = mass
cp = specific heat of gas at constant pressure

To obtain the temperature in the cycle of the removal of heat (4) you must have the values of compression ratio in cycles 3 (V3) and 4 (V4) and the adiabatic constant of air (k), and the temperature in the expansion cycle (3).



T4 = T3 * (V3/V4) ^ (k-1);

where:

T3 = temperature in cycle 3
V3 = volume in the cycle 3
V4 = volume in the cycle 4
k = constant adiabatic air



If you have any questions about the theory of everything, or to obtain Q1 or mass simply send an email. I am new in this form too and do not know to use mathematical symbols, if someone can explain me please tell me.

I hope this can help.
 

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