Ideal Gas Law

O

For dry air O

For water vapor O

подпись: for dry air o
for water vapor o
R =R^ = 1545.32 = 53 g _ lbfy(lbm _R) : Mn 28.965

R„=^ = 154532 = 85.78ft-lbf/(lbm-R) :

18.02

The following data for US STANDARD A TSMOPHERE are from ASHARE Handbook of Fundamentals (Chapter6). Several assumptions are introduced such as:

The atmosphere consists of dry air that behaves as an ideal gas.(see pg.50 in the textbook)

Table 1 Standard Atmospheric Data for Altitudes to 10 000 m

Altitude, m

Temperature, °C

Pressure, kPa

-500

18.2

107.478

0

15.0

101.325

500

11.8

95.461

1000

8.5

89.875

1500

5.2

84.556

2000

2.0

79.495

2500

-1.2

74.682

3000

-4.5

70.108

4000

-11.0

61.640

5000

-17.5

54.020

6000

—24.0

47.181

7000

-30.5

41.061

8000

-37.0

35.600

9000

-43.5

30.742

10000

-50

26.436

12000

-63

19.284

14000

-76

13.786

16000

-89

9.632

18000

-102

6.556

20000

-115

4.328

Data adapted from NASA (1976).

Table 1 Standard Atmospheric Data for Altitudes to 60,000 ft

Pressure

Altitude, ft

Temperature, °F

In. Hg

Psia

-1000

62.6

31.02

15.236

-500

60.8

30.47

14.966

0

59.0

29.921

14.696

500

57.2

29.38

14.430

1000

55.4

28.86

14.175

2000

51.9

27.82

13.664

3000

48.3

26.82

13.173

4000

44.7

25.82

12.682

5000

41.2

24.90

12.230

6000

37.6

23.98

11.778

7000

34.0

23.09

11.341

8000

30.5

22.22

10.914

9000

26.9

21.39

10.506

10,000

23.4

20.58

10.108

15,000

5.5

16.89

8.296

20,000

-12.3

13.76

6.758

30,000

-47.8

8.90

4.371

40,000

-69.7

5.56

2.731

50,000

-69.7

3.44

1.690

60,000

-69.7

2.14

1.051

Data adapted from NASA (1976).

Reference p and T are functions of altitude. Formula for p as function of elevation Z:

P[psi] = 14.696 (1-6.8753×10"6 Zfft])5 2559 p[barj = 1.013 (1-2.256X10’6 Z[m])5 2559

Example

Sea level: p=14.696 psi, T=59°F

Posted in Fundamentals of Heating. Ventilating, and Air-Conditioning


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