Consider a modification of the air-standard Otto cycle in which the isentropic compression and expansion processes are each replaced with polytropic processes having n = 1.35. The compression ratio is 10 for the modified cycle. At the beginning of compression, p1 = 1 bar and T1 = 310 K. The maximum temperature during the cycle is 2200 K. Determine: (a) the heat transfer and work in kJ per kg of air for each process in the modified cycle (see image below). (b) the percent thermal efficiency. (c) the mean effective pressure, in bar.

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On my online homework, it says the answer for part b, 40.156% is incorrect.

 

Consider a modification of the air-standard Otto cycle in which the isentropic compression and expansion processes are each replaced with polytropic processes having n = 1.35. The compression ratio is 10 for the modified cycle. At the beginning of compression, p1 = 1 bar and T1 = 310 K. The maximum temperature during the cycle is 2200 K.

Determine:


(a) the heat transfer and work in kJ per kg of air for each process in the modified cycle (see image below).

(b) the percent thermal efficiency.

(c) the mean effective pressure, in bar.

 

### Part A

#### Determine the heat transfer and work in kJ per kg of air for each process in the modified cycle. Note the air is the closed system.

**Process 1-2:**

\[ \frac{Q_{12}}{m} = \text{______ kJ/kg} \qquad \frac{W_{12}}{m} = \text{______ kJ/kg} \]

**Process 2-3:**

\[ \frac{Q_{23}}{m} = \text{______ kJ/kg} \qquad \frac{W_{23}}{m} = \text{______ kJ/kg} \]

**Process 3-4:**

\[ \frac{Q_{34}}{m} = \text{______ kJ/kg} \qquad \frac{W_{34}}{m} = \text{______ kJ/kg} \]

**Process 4-1:**

\[ \frac{Q_{41}}{m} = \text{______ kJ/kg} \qquad \frac{W_{41}}{m} = \text{______ kJ/kg} \]

### Explanation

In these equations:
- \( Q_{ij} \) represents the heat transfer between states \( i \) and \( j \).
- \( W_{ij} \) represents the work done between states \( i \) and \( j \).
- \( m \) stands for the mass of the air in kg.
- The unit for both heat transfer and work is kilojoules per kilogram (kJ/kg).

The blue icon with the letter "i" next to each equation might indicate an information button typically used in educational platforms to provide additional details if clicked, though this functionality isn't visible in a static image.
Transcribed Image Text:### Part A #### Determine the heat transfer and work in kJ per kg of air for each process in the modified cycle. Note the air is the closed system. **Process 1-2:** \[ \frac{Q_{12}}{m} = \text{______ kJ/kg} \qquad \frac{W_{12}}{m} = \text{______ kJ/kg} \] **Process 2-3:** \[ \frac{Q_{23}}{m} = \text{______ kJ/kg} \qquad \frac{W_{23}}{m} = \text{______ kJ/kg} \] **Process 3-4:** \[ \frac{Q_{34}}{m} = \text{______ kJ/kg} \qquad \frac{W_{34}}{m} = \text{______ kJ/kg} \] **Process 4-1:** \[ \frac{Q_{41}}{m} = \text{______ kJ/kg} \qquad \frac{W_{41}}{m} = \text{______ kJ/kg} \] ### Explanation In these equations: - \( Q_{ij} \) represents the heat transfer between states \( i \) and \( j \). - \( W_{ij} \) represents the work done between states \( i \) and \( j \). - \( m \) stands for the mass of the air in kg. - The unit for both heat transfer and work is kilojoules per kilogram (kJ/kg). The blue icon with the letter "i" next to each equation might indicate an information button typically used in educational platforms to provide additional details if clicked, though this functionality isn't visible in a static image.
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