1. 9. GAS LAWS AND ENGINE POWER
BTE 1013
ENGINEERING SCIENCEs
9. GAS LAWS AND ENGINE POWER
NAZARIN B. NORDIN

2. GAS LAWS
Ideal Gases
Gases are fluids, differing from liquids in that while liquids are practically incompressible and possess a definite volume, gases are readily compressible and can change their volume. The following are three laws which are found to be reasonably obeyed by the so-called permanent gases, e.g. oxygen and nitrogen, at temperatures in the region of room temperature. A gas which is considered to obey these laws exactly is called an ideal gas.

3. PV = nRT Ideal Gas Law R – Universal Gas Constant = 8.315 J/(mol K)
n (mol) = mass (g) / molecular mass (g/mol)
Avogadro’s Number – number of molecules per mole
NA = 6.02 x 1023
PV = NkT
k – Boltzmann’s Constant
k = R = J/(mol K) = 1.38 x J/K
NA = 6.02 x 1023/mole

4. Boyle’s Law – the volume of a gas is inversely proportional to the pressure applied to it when the temperature is kept constant
V a 1 P
Charles’s Law – the volume of a given amount of gas is directly proportional to the absolute temperature when the pressure is kept constant
V a T
T -absolute temperature

5. Engine Performance Criteria
Indicated Mean Effective Pressure, Pi or i.m.e.p. ,
Pi =
= i.m.e.p.
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6. Reciprocating Internal Combustion Engine SME 2423-2006/2007-2

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8. Reciprocating Internal Combustion Engine SME 2423-2006/2007-2

9. Indicated Power, IP
IP =
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10. Reciprocating Internal Combustion Engine SME 2423-2006/2007-2

11. Torque, T
Brake Power, BP
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12. Reciprocating Internal Combustion Engine SME 2423-2006/2007-2

13. BP=
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14. = BP/IP
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18. ,(Specific fuel consumption, sfc)
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20. Volumetric Efficiency, v
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22. Energy Balance
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23. Morse Test
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30. THANK YOU