流動的氣體所具有的焓與動能之和，表示其總能量，就是說,氣體的總能量取決于氣體的狀態(tài)參數(shù)溫度T與速度c。當氣流與外界沒有能量交換,按照定嫡過程將氣體速度完全滯止到零時所對應(yīng)的溫度稱為滯止溫度(又稱總溫,以T.表示。它也是氣體的一個狀態(tài)參數(shù)。如果流動的氣體與速度被滯止到零的氣流具有相同的總能量，則可用氣體狀態(tài)參數(shù)工。來表示其總能量,即:
相應(yīng)于滯止溫度的焓稱為滯止館(或總焓)，以h.表示:
[例3- 1]試確定某油田氣在壓力為30X10Pa和溫度為90C時的比熱容比、溫度絕熱指數(shù)kt及容積絕熱指數(shù)Kv。 已知油田氣組分為:
(1)查各組分氣體的參數(shù):
(2)求混合器的摩爾質(zhì)量M及各組分質(zhì)量分數(shù)gi：
(3)求油田氣當量臨界參數(shù)與對比參數(shù)：
油田氣當量臨界溫度：
油田氣當量臨界壓力
對比壓力
對比溫度
(4)求比熱容比：
混合氣的比定壓熱容為、；
查圖3-6(a)得：
查圖3-6(b)得：
比熱容比：
(5)求kt及kv：
由圖3-7和圖3-8查得：X=0.2，Y=1.02。
混合氣氣體常數(shù)：
查得3-5得壓縮因子：Z=0.97。
可見
The sum of enthalpy and kinetic energy of a flowing gas represents its total energy, which means that the total energy of a gas depends on its state parameters, temperature T and velocity c. When there is no energy exchange between the airflow and the outside world, the temperature corresponding to the complete stagnation of the gas velocity to zero according to the stagnation process is called the stagnation temperature (also known as the total temperature, represented by T.). It is also a state parameter of the gas. If the flowing gas has the same total energy as the airflow whose velocity is stagnated to zero, the gas state parameter can be used to represent its total energy, that is:
The enthalpy corresponding to the stagnation temperature is called the stagnation enthalpy (or total enthalpy), denoted by h express:
[Example 3-1] Determine the specific heat capacity ratio, temperature adiabatic index kt, and volume adiabatic index Kv of a certain oilfield gas at a pressure of 30X10Pa and a temperature of 90C. The known composition of oilfield gas is:
(1) Check the parameters of each component gas:
(2) Calculate the molar mass M of the mixer and the mass fraction gi of each component:
(3) Calculate the critical and comparative parameters of oil field gas equivalence:
Oil field gas equivalent critical temperature:
Oilfield gas equivalent critical pressure
reduced pressure
reduced temperature
(4) Calculate the specific heat ratio:
The specific heat capacity at constant pressure of the mixture is;
According to Figure 3-6 (a):
According to Figure 3-6 (b):
Specific heat ratio:
(5) Request kt and kv:
According to Figures 3-7 and 3-8: X=0.2，Y=1.02。
Gas constant of mixed gas:
Calculate the compression factor of 3-5: Z=0.97。
it is thus clear that
