CN107860675A - A kind of method for determining fuel vapor pressure and vaporization enthalpy - Google Patents
A kind of method for determining fuel vapor pressure and vaporization enthalpy Download PDFInfo
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- CN107860675A CN107860675A CN201711178787.0A CN201711178787A CN107860675A CN 107860675 A CN107860675 A CN 107860675A CN 201711178787 A CN201711178787 A CN 201711178787A CN 107860675 A CN107860675 A CN 107860675A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N7/00—Analysing materials by measuring the pressure or volume of a gas or vapour
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Abstract
The invention provides a kind of method for determining fuel vapor pressure and vaporization enthalpy, comprise the following steps：Instrument is opened, any fuel oil sample is not put into crucible, crucible is heated, volatile impurity is removed with inert gas；Then room temperature is dropped in inert gas shielding；Fuel oil sample is positioned in the crucible in Instrument, by the use of inert gas as work gas, starts Instrument, Instrument operating temperature be T, after the constant temperature t times, is changed with time relation by Instrument record fuel oil quality percent loss；Changed with time straight line by drawing fuel oil quality percent loss, straight slope is the mass change dm/dt of EVAP；By Langmuir equations, the vapour pressure p of fuel oil sample is calculated；Using Clausius Clapeyron equations, the vaporization enthalpy Δ H of fuel oil is calculatedvap.The present invention is applied to the measurement of various vapour pressure fuel oils, and can obtain the vapour pressure under specified temp, has the characteristics that to realize that full-automatic, high accuracy, materials are few.
Description
Technical field
The present invention relates to fuel oil physical property of the Earth's materials determination techniques field, more particularly to a kind of measure fuel vapor pressure and steaming
The method for sending out enthalpy.
Background technology
Novel fuel, such as nano fuel, biological hydrogen-supplemented fuel etc., it is substitute of diesel fuel widely studied at present, therefore
It is necessary to understand its Basic Physical Properties parameter.And vapour pressure is its important parameter, the higher molecule of energy has disengaging liquid level in liquid
Into the tendency of gas phase, vapour pressure is exactly the physical quantity for being used for weighing this pilot process dynamic trend.Therefore, vapour pressure is to comment
The important indicator of valency material stability.
The method of measurement vapour pressure has a lot, such as static method, dynamic method and reid method.The original of static method and dynamic method
Manage and be, under certain temperature, liquid is put into the closed container of vacuum, the larger molecule of kinetic energy escapes into gas phase from liquid phase, moves
The less molecule of energy can impinge onto liquid phase by gas phase.It is to steam up to gaseous pressure during vapor liquid equilibrium when both speed are equal
Air pressure.Static method at a certain temperature using etc. pressure pipe direct measurement liquid saturated vapor pressure, the method be difficult determine gas-liquid
Poised state, reaching the time of balance can not quantify；Measurement then needs liquid nitrogen to deaerate, and sample dosage is big；Essence is measured under high temperature
Degree is poor, and measurement apparatus is more complicated and broken.Dynamic method measures the boiling point of liquid at a particular pressure, the method can not determine to
The vapour pressure at temperature is determined, suitable for the relatively low material of vapour pressure under normal temperature.Reid method measurement vapour pressure is according to air chamber
Volume is about 500mL, and fuel chambers are about 125mL, i.e., gas, liquid volume ratio is 4:1, temperature is used special under the conditions of being 37.8 DEG C
The vapour pressure that Reid vapour pressure (RVP) analyzer measures, this method are applied to the vapour pressure of measure effumability oil product, and this side
Method dosage is big, is not suitable for the measurement of more valuable fuel oil；Testing time is longer, temperature change in oscillatory process and with the naked eye
The determination influences factors such as observation pressure gauge reading are more, and error is big.
Number of patent application：201220721637.6, devise a kind of saturated vapour pressure analyzer based on static method, this dress
The vapour pressure using static method measurement liquid substance is put, automaticity is high, and security is good.But the device is only applicable to 10-1-
Tested in the range of 102Pa low-vapor pressure, be not suitable for the measurement of the higher fuel oil of vapour pressure.
Number of patent application：201410569158.0 devising a kind of test liquid material, steam is pressed under the high temperature conditions
Put, the device uses number pressure of the temperature and pressure test system record liquid substance under condition of different temperatures in computer
According to, so as to measure the vapour pressure of liquid substance under the high temperature conditions, this method reduces test labor intensity to a certain extent,
But the measurement being only applicable under hot environment；In addition, the applicable pressure limit of this device is not yet handed in the invention.
The content of the invention
For Shortcomings in the prior art, calculate EVAP enthalpy the invention provides a kind of constant temperature heating remeasurement, steam
The method of air pressure, suitable for the measurement of various vapour pressure fuel oils, and the vapour pressure under specified temp can be obtained, program is set
Complete experiment；Calculated using known equation, reduce error caused by manual measurement.Compared with existing correlation technique,
Have the characteristics that to realize that full-automatic, high accuracy, materials are few, combine the actual experimental enviroment of fuel oil, the actual use to fuel oil
Have important practical significance.
The present invention is to realize above-mentioned technical purpose by following technological means.
A kind of method for determining fuel vapor pressure and vaporization enthalpy, comprises the following steps：
S01：Instrument is opened, any fuel oil sample is not put into crucible, crucible is heated, is removed and volatilized with inert gas
Property impurity；Then room temperature is dropped in inert gas shielding；
S02：The fuel oil sample that quality is m is positioned in the crucible in Instrument, by the use of inert gas as work gas, opened
Dynamic Instrument, Instrument operating temperature is T, wherein T ∈ [T0,TMax]；
S03：Original state Instrument work temperature=T0, after the constant temperature t times, pass through Instrument and record fuel oil quality and damage
Percentage is lost to change with time relation；
S04：Crucible is taken out, addition fuel oil sample to weight is m, adjustment Instrument temperature T, T=T0+ i Δ T, and i=1；
After the constant temperature t times, fuel oil quality percent loss is recorded by Instrument and changed with time relation；
S05：I=i+1；As T >=TmaxWhen, then stop Instrument；As T≤TmaxWhen, then redirect S04；
S06：Evaporation capacity by drawing fuel oil changes with time straight line, and straight slope is the mass change of EVAP
Rate-dm/dt；
S07：According to the mass change-dm/dt of the EVAP drawn, by Langmuir equations, fuel oil is calculated
The vapour pressure p of sample；Using Clausius-Clapeyron equations, the vaporization enthalpy Δ H of fuel oil is calculatedvap。
Further, the inert gas is nitrogen, and the inert gas flow is 40-80mL/min.
Further, the working time t is 5-10min.
Further, the section of the Instrument work temperature is (100-140) DEG C.
Further, T=3-8 DEG C of Δ in the S04 steps.
Further, the fuel oil sample quality m is 10-20mg.
Further, the T0And TMAXTemperature be more than the fuel oil sample boiling temperature.
The beneficial effects of the present invention are：
1. the method for measure fuel vapor pressure of the present invention and vaporization enthalpy, in the method for the test of vapour pressure, heat
Weight method has obvious advantage.Thermogravimetric instrument can quickly study some physical characteristics of fuel oil in a dynamic condition, simple to operate,
Sample dosage is few, and research and development of the result of the test to novel fuel have important directive significance with practical application.
2. the method for measure fuel vapor pressure of the present invention and vaporization enthalpy, suitable for the survey of various vapour pressure fuel oils
Amount, and the vapour pressure under specified temp can be obtained, set program to complete to test；Calculated, reduced using known equation
Error caused by manual measurement.
3. the method for measure fuel vapor pressure of the present invention and vaporization enthalpy, compared with existing correlation technique, has
The features such as full-automatic, high accuracy, materials are few is realized, combines the actual experimental enviroment of fuel oil, the actual use to fuel oil has
Important realistic meaning.
Brief description of the drawings
Fig. 1 is n-tetradecane fuel oil quality M of the present invention and time t graph of relation.
Fig. 2 is the relation curve that n-tetradecane fuel vapor of the present invention presses p and v.
Fig. 3 is the comparison of the vapor pressure values that the present invention determines and literature value.
Embodiment
Below in conjunction with the accompanying drawings and specific embodiment the present invention is further illustrated, but protection scope of the present invention is simultaneously
Not limited to this.
The method of measure fuel vapor pressure and vaporization enthalpy of the present invention, comprises the following steps：
S01：Instrument is opened, any fuel oil sample is not put into crucible, crucible is heated, is removed and volatilized with inert gas
Property impurity；Then room temperature is dropped in inert gas shielding；
S02：The fuel oil sample that quality is m is positioned in the crucible in Instrument, by the use of inert gas as work gas, opened
Dynamic Instrument, Instrument operating temperature is T, wherein T ∈ [T0,TMax]；
S03：Original state Instrument work temperature=T0, after the constant temperature t times, pass through Instrument and record fuel oil quality and damage
Percentage is lost to change with time relation；
S04：Crucible is taken out, addition fuel oil sample to weight is m, adjustment Instrument temperature T, T=T0+ i Δ T, and i=1；
After the constant temperature t times, fuel oil quality percent loss is recorded by Instrument and changed with time relation；
S05：I=i+1；As T >=TmaxWhen, then stop Instrument；As T≤TmaxWhen, then redirect S04；
S06：Evaporation capacity by drawing fuel oil changes with time straight line, and straight slope is the mass change of EVAP
Rate-dm/dt；
S07：According to the mass change-dm/dt of the EVAP drawn, by Langmuir equations, fuel oil is calculated
The vapour pressure p of sample；Using Clausius-Clapeyron equations, the vaporization enthalpy Δ H of fuel oil is calculatedvap。
It is below that n-tetradecane is embodiment explanation from fuel oil,
S01：Instrument is opened, is not put into any fuel oil sample in crucible, crucible is heated, by the use of nitrogen as protecting gas,
Flow is 50mL/min, in 100 DEG C of constant temperature 60min, to remove volatile impurity；Then room is dropped in inert gas shielding
Temperature；
S02：The n-tetradecane fuel oil sample that quality is 20mg is positioned in the crucible in Instrument, guarantor is used as by the use of nitrogen
Gas is protected, flow 50mL/min, starts Instrument, Instrument operating temperature is T, wherein T ∈ [100,140]；
S03：Original state Instrument work temperature=100, after the constant temperature 10min times, fuel oil matter is recorded by Instrument
Amount percent loss changes with time relation；
S04：Crucible is taken out, addition n-tetradecane fuel oil sample to weight is 20mg, adjustment Instrument temperature T, T=100+
5i, and i=1；After the constant temperature 10min times, fuel oil quality percent loss is recorded by Instrument and changed with time relation；
S05：I=i+1；As T >=140, then stop Instrument；As T≤140, then S04 is redirected；
S06：Evaporation capacity by drawing fuel oil changes with time straight line, and straight slope is the mass change of EVAP
Rate-dm/dt, as shown in figure 1, when Δ m is t fuel oil evaporative mass, positive 14 under different temperatures are depicted in Fig. 1
Alkane EVAP mass loss changes with time straight line.
S07：According to the mass change-dm/dt of the EVAP drawn, by Langmuir equations, fuel oil is calculated
The vapour pressure p of sample；Using Clausius-Clapeyron equations, the vaporization enthalpy Δ H of fuel oil is calculatedvap.It is specific as follows：
1. vapour pressure：
Vaporization phenomenon is described with Langmuir equations：
-Avap -1Dm/dt=p α (M/2 π RT)1/2 (1)
Wherein：
AvapFor evaporation surface, m2；
- dm/dt is the mass change of fuel oil sample；
P is saturated vapour pressure, kPa；
α is vaporization constant, and under the conditions of gas is protected, α is constant；
M is molal weight；
R is gas constant, 8.314Jmol-1·K-1
T is thermodynamic temperature.K.
Formula (1) is rearranged to obtain
P=α-1(-Avap -1dm/dt)(2πRT/M)1/2 (2)
Make k=in formula (2) (2 π R)1/2·α-1, k is temperature independent empirical parameter, v=(- Avap -1dm/dt)(T/M
)1/2, then formula (2) be changed into：
P=kv (3)
According to known-dm/dt, Avap, T and M v can be calculated, be can obtain according to Antoine equations under its different temperatures
Vapor pressure values, by the vapour pressure p of reference material to v map, obtain a straight line by origin, such as Fig. 2, slope is this
K values under experimental enviroment.
According to Antoine equations
The vapour pressure of fuel oil can be calculated.Wherein A, B, C are Antoine constants.
According to known k values, thermogravimetric experiment is carried out to other fuel oils, obtains its-dm/dt, calculates v, substitutes into formula (3), can
Draw the vapor pressure values p of the various fuel oils under different temperatures.
2. vaporization enthalpy
Vapour pressure is set to be temperature dependent connection with enthalpy of vaporization by Clausius-Clapeyron equations:
Ln p=c+ Δs Hvap/RT (5)
Because EVAP amount is smaller, it is believed that the evaporation liquid surface area in crucible is constant, therefore has
p∝(-dm/dt)T1/2 (6)
Then obtain fit equation
ln[(-dm/dt)T1/2]=d+ Δs Hvap/RT (7)
By ln [(- dm/dt) T1/2] 1/T is mapped, straight line is obtained, its slope is-Δ Hvap/ RT, can according to slope
Calculate vaporization enthalpy Δ Hvap。
Verified using hexadecane fuel oil as test specimen, using hexadecane fuel oil as test specimen, according to
The empirical parameter k that the environment obtains, is calculated its vapour pressure, makees vapour pressure p and temperature T relationship curve and data in literature pair
Than as shown in figure 3, both meet preferably, illustrating that constant temperature DTG can preferably be used for the vapour pressure for determining liquid substance.
The embodiment is preferred embodiment of the invention, but the present invention is not limited to above-mentioned embodiment, not
Away from the present invention substantive content in the case of, those skilled in the art can make it is any it is conspicuously improved, replace
Or modification belongs to protection scope of the present invention.
Claims (7)
- A kind of 1. method for determining fuel vapor pressure and vaporization enthalpy, it is characterised in that comprise the following steps：S01：Instrument is opened, any fuel oil sample is not put into crucible, crucible is heated, it is miscellaneous to remove volatility with inert gas Matter；Then room temperature is dropped in inert gas shielding；S02：The fuel oil sample that quality is m is positioned in the crucible in Instrument, by the use of inert gas as work gas, starts heat Weight instrument, Instrument operating temperature is T, wherein T ∈ [T0,TMax]；S03：Original state Instrument work temperature=T0, after the constant temperature t times, pass through Instrument and record fuel oil quality and lose percentage Than the relation of changing with time；S04：Crucible is taken out, addition fuel oil sample to weight is m, adjustment Instrument temperature T, T=T0+ i Δ T, and i=1；Constant temperature t After time, fuel oil quality percent loss is recorded by Instrument and changed with time relation；S05：I=i+1；As T >=TmaxWhen, then stop Instrument；As T≤TmaxWhen, then redirect S04；S06：Evaporation capacity by the drawing fuel oil straight line that changes with time obtains straight slope, and straight slope is EVAP Mass change-dm/dt；S07：According to the mass change-dm/dt of the EVAP drawn, by Langmuir equations, fuel oil sample is calculated Vapour pressure p；Using Clausius-Clapeyron equations, the vaporization enthalpy Δ H of fuel oil is calculatedvap。
- 2. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the inert gas For nitrogen, the inert gas flow is 40-80mL/min.
- 3. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the working time T is 5-10min.
- 4. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the Instrument work The section for making temperature T is (100-140) DEG C.
- 5. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the S04 steps In T=3-8 DEG C of Δ.
- 6. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the fuel oil sample Quality m is 10-20mg.
- 7. the method for measure fuel vapor pressure according to claim 1 and vaporization enthalpy, it is characterised in that the T0And Tmax's Temperature is more than the boiling temperature of the fuel oil sample.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021052097A1 (en) * | 2019-09-19 | 2021-03-25 | 江苏大学 | Measurement system and method for oxidization characteristic parameter of liquid blended fuel |
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| US5266492A (en) * | 1992-11-13 | 1993-11-30 | Baxter International Inc. | Rapid method for determining critical vapor pressure |
| CN103091196A (en) * | 2012-12-07 | 2013-05-08 | 常州大学 | Method for measuring 2-amino-5-nitropyridine saturated vapor pressure |
| CN103983537A (en) * | 2014-05-22 | 2014-08-13 | 李荣华 | Method for rapidly determining vapor pressure of solid chemicals |
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2017
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| US5266492A (en) * | 1992-11-13 | 1993-11-30 | Baxter International Inc. | Rapid method for determining critical vapor pressure |
| CN103091196A (en) * | 2012-12-07 | 2013-05-08 | 常州大学 | Method for measuring 2-amino-5-nitropyridine saturated vapor pressure |
| CN103983537A (en) * | 2014-05-22 | 2014-08-13 | 李荣华 | Method for rapidly determining vapor pressure of solid chemicals |
Non-Patent Citations (2)
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| 崔蕊蕊 等: "热重分析法测定氟唑活化酯的饱和蒸气压", 《世界农药》 * |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2021052097A1 (en) * | 2019-09-19 | 2021-03-25 | 江苏大学 | Measurement system and method for oxidization characteristic parameter of liquid blended fuel |
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Application publication date: 20180330 |