Question

3600 KJ heat is entered in a gas cylinder. calculate the value of deltaE

​

Answer 1

Answer:

4-5 A piston-cylinder device contains nitrogen gas at a specified state. The boundary work is to be

determined for the polytropic expansion of nitrogen.

Properties The gas constant for nitrogen is 0.2968 kJ/kg.K (Table A-2).

Analysis The mass and volume of nitrogen at the initial state are

0.07802 kg (0.2968 kJ/kg.K)(120 273 K)

(130 kPa)(0.07 m )

3

1

1 1 RT

P

m

V

3

3

2

2

2 0.08637 m

100 kPa

(0.07802 kg)(0.2968 kPa.m /kg.K)(100 273 K) P

mRT V

N2

130 kPa

120qC

The polytropic index is determined from

(130 kPa)(0.07 m ) (100 kPa)(0.08637 m ) 1.249 3 3 P1 1 P2 2 o on n n n n V V

The boundary work is determined from

1.86 kJ

1 1.249

(100 kPa)(0.08637 m ) (130 kPa)(0.07 m )

Answer 2

Answer:

4-5 A piston-cylinder device contains nitrogen gas at a specified state. The boundary work is to be

determined for the polytropic expansion of nitrogen.

Properties The gas constant for nitrogen is 0.2968 kJ/kg.K (Table A-2).

Analysis The mass and volume of nitrogen at the initial state are

0.07802 kg (0.2968 kJ/kg.K)(120 273 K)

(130 kPa)(0.07 m )

3

1

1 1 RT

P

m

V

3

Explanation: