What is meant by polytropic gas?
The term “polytropic” was originally coined to describe any reversible process on any open or closed system of gas or vapor which involves both heat and work transfer, such that a specified combination of properties were maintained constant throughout the process.
How do you find the polytropic constant?
1 Polytropic Process. where v = 1 / ρ is the specific volume, n is the polytropic index, and C is a constant. The condition of represents an isobaric process, represents an isothermal process, n = γ = c p / c v represents an isentropic process, and represents an isochoric process. (6.159)
What is K in polytropic process?
Here k is the ratio of the specific heat at constant pressure, CP, to specific heat at constant volume, CV. The specific heats will be discussed later.
What is PV n constant?
PV=nRT. The ideal gas Law PV = nRT. Robert Boyle found PV = a constant. That is, the product of the pressure of a gas times the volume of a gas is a constant for a given sample of gas. In Boyle’s experiments the Temperature (T) did not change, nor did the number of moles (n) of gas present.
What is an ideal polytropic gas?
n = +∞ Equivalent to an isochoric process (constant volume) When the index n is between any two of the former values (0, 1, γ, or ∞), it means that the polytropic curve will cut through (be bounded by) the curves of the two bounding indices. For an ideal gas, 1 < γ < 5/3, since by Mayer’s relation.
What is non quasi static process?
In a non-quasi-static process, the states between A and B are not known, and hence no path can be drawn. It may follow the dashed line as shown in the figure or take a very different path.
What is ideal polytropic gas?
Page 2. Polytropic Process of an Ideal Gas. • The relationship between the pressure and volume during. compression or expansion of an ideal gas can be described. analytically.
What is the R in PV nRT?
The ideal gas law is: pV = nRT, where n is the number of moles, and R is universal gas constant. The value of R depends on the units involved, but is usually stated with S.I. units as: R = 8.314 J/mol·K. This means that for air, you can use the value R = 287 J/kg·K.
Are adiabatic processes Polytropic?
The key difference between adiabatic and polytropic processes is that in adiabatic processes no heat transfer occurs whereas in polytropic processes heat transfer occurs. Adiabatic and polytropic are two thermodynamic processes that relate to heat transfer in systems. …
What is CP minus CV?
In Section 8.1 we pointed out that the heat capacity at constant pressure must be greater than the heat capacity at constant volume. We also showed that, for an ideal gas, CP = CV + R, where these refer to the molar heat capacities.
How is the polytropic process of an ideal gas described?
Polytropic Process of an Ideal Gas. • The relationship between the pressure and volume during compression or expansion of an ideal gas can be described analytically. One form of this relationship is given by the equation pVn = constant.
When is a polytropic process between two states constant?
• For a Polytropic process between two states 1-2 p V p Vn constant 2 2 n 1 1 = =. Remarks. • When n=0, p = constant, and the process is a constant pressure or an isobaric process. • When n=1, pV = constant, and the process is a constant temperature or an isothermal. process.
How is the polytropic index in gas field engineering?
David A. Simpson P.E., in Practical Onshore Gas Field Engineering, 2017 Dynamic compression is a polytropic process, meaning that the polytropic index (n) in Eq. (8.3) is not equal to ratio of specific heats ( k) or 1.0 ( n = k would be adiabatic, n =1 would be isothermal).
Is the polytropic index of dynamic compression constant?
Dynamic compression is a polytropic process, meaning that the polytropic index (n) in Eq. (8.3) is not equal to ratio of specific heats ( k) or 1.0 ( n = k would be adiabatic, n =1 would be isothermal). Entropy need not be constant, the process need not be reversible (but it generally is), and heat transfer need not be reasonably close to zero.