CN101858877A - Method for detecting mixing ratios of biodiesel blended fuels - Google Patents

Abstract

The invention discloses a method for detecting the mixing ratios of biodiesel blended fuels, which is characterized in that: by measuring and analyzing the relative dielectric constants of biodiesel blended fuels with different mixing ratios, the mapping relationship between biodiesel mixing ratio and relative dielectric constant is determined and a dielectric constant-based biodiesel mixing ratio test model is built; and the mixing ratios of the biodiesel blended fuels are determined by measuring and calibrating the dielectric constants. The detecting method of the invention determines the mapping relationship between the biodiesel mixing ratios and the relative dielectric constants and builds the dielectric constant-based biodiesel mixing ratio test model by measuring and analyzing the relative dielectric constants of the biodiesel blended fuels with different mixing ratios through a elative dielectric constant test method, and determines the mixing ratios of the biodiesel blended fuels by measuring the dielectric constant, so the method provides theoretical foundation for the development of mixing ratio test equipment, contributes to the improvement of the operational performance of a biodiesel engine, has a great significance for the development and popularization of the biodiesel blended fuels in the future in China and also fills in the gap of a biodiesel blended fuel mixing ratio vehicle-carried detection method.

Description

A kind of method for detecting mixing ratios of biodiesel blended fuels

Technical field

The invention belongs to biodiesel fuel blend Quality Detection technical field, especially relate to method for detecting mixing ratios of biodiesel blended fuels.

Background technology

Biodiesel can directly apply on the vehicle diesel engine, but, the key indexs such as cetane rating, kinematic viscosity and flash-point of the biodiesel fuel blend of evidence different proportion, different qualities all have certain otherness, therefore to obtain best diesel engine usability, the oil spout of diesel engine should be carried out suitable adjustment with the different of biodiesel fuel blend mixing ratio with injection pressure constantly, so is necessary the mixing ratio of biodiesel fuel blend is accurately tested.The research of China's prior biological diesel oil on vehicle diesel engine, major part concentrates in the influence of biodiesel for vehicle diesel engine dynamic property, economy, emission behavior.For biodiesel engine usability how to optimize the Different Provenances different mixing proportion, problems such as vehicle-mounted detection of biodiesel for automobile fuel blend mixing ratio and the vehicle-mounted detection of quality are not also carried out deep research.

Summary of the invention

The purpose of this invention is to provide a kind of relative dielectric constant and determine the detection method of mixing ratio, for the exploitation of biological diesel blended fuel quality and mixing ratio detection system is provided fundamental basis by measurement different mixing proportion biodiesel fuel blend.

For achieving the above object, the invention provides a kind of method for detecting mixing ratios of biodiesel blended fuels, it is characterized in that: by the relative dielectric constant value of different mixing proportion biodiesel fuel blend is measured, analyze, determine the mapping relations between biodiesel mixing ratio and the relative dielectric constant, structure is based on the biodiesel mixing ratio test model of specific inductive capacity, by the measurement and the demarcation of specific inductive capacity, determine biodiesel fuel blend mixing ratio.

The test model of biodiesel fuel blend mixing ratio is C=96 ε _r-208.5, in the formula: ε _rFor relative dielectric constant value, the C of the fuel blend that records in real time is the mixing ratio of fuel blend.

Detection method of the present invention is by the relative dielectric constant method of testing, relative dielectric constant value to different mixing proportion biodiesel fuel blend is measured, analyze, determine the mapping relations between biodiesel mixing ratio and the relative dielectric constant, make up the mixing ratio test model, by recording dielectric constant values, determine biodiesel fuel blend mixing ratio, for the exploitation of mixing ratio checkout equipment provides theoretical foundation, help the raising of biodiesel engine usability, for China from now on biodiesel fuel development and promoted the use of very important meaning, also remedied simultaneously the blank of the vehicle-mounted detection method of biodiesel fuel blend mixing ratio.

Description of drawings

Figure 1A group relative dielectric constant scatter diagram;

Fig. 2 B group relative dielectric constant scatter diagram;

The rectilinear that Fig. 3 A group returns;

The rectilinear that Fig. 4 B group returns.

Embodiment

Embodiment, biodiesel is mixed with the petrifaction diesel (No. 35 diesel oil and No. 0 diesel oil) of two kinds of trades mark respectively and is obtained two groups of biodiesel fuel blends, is the A group with the fuel blend of biodiesel and-No. 35 diesel oil configurations; Fuel blend with biodiesel and No. 0 diesel oil configuration is the B group.The blending ratio of two groups of fuel blends is identical.Detailed process is as follows:

1) petrifaction diesel of biodiesel and two kinds of trades mark respectively by volume 0%, 5%, 10%, 20%, 40%, 50%, 80%, 100% ratio prepare the fuel blends of 2 groups of each 8 kinds of blending ratios, every kind of fuel blend 50ml, test the relative dielectric constant value of each sample, triplicate is operated, and gets the mean value of relative dielectric constant;

2) the relative dielectric constant value of two groups of biodiesel fuel blends see Table 1, table 2, by data in table 1 and the table 2, with biodiesel fuel blend different mixing proportion is ordinate, relative dielectric constant with the biodiesel fuel blend is a horizontal ordinate, draw scatter diagram 1 and Fig. 2, according to the scatter diagram of drawing out 1 and Fig. 2 as can be seen, relative dielectric constant and biodiesel fuel blend mixing ratio are linear substantially, and gained The data one-variable linear regression method is handled;

The theoretical equation of one-variable linear regression can be expressed as:

$\hat{y}=a+\mathrm{bx}$

In the formula,

Be the calculated value of the dependent variable y that obtains according to regression equation, i.e. the mixing ratio of biodiesel fuel blend, a, b are the coefficient in the regression equation; X is an independent variable, the relative dielectric constant value of the promptly actual biodiesel fuel blend that records.

Each measured data y _iWith his corresponding calculated value

Between residual error:

y _i＝y _i-(a+bx _i)

Through calculating, obtain:

$l_{\mathrm{xx}}=\underset{1}{\overset{n}{\mathrm{\Σ}}}{(x_i-\stackrel{\‾}{x})}^2$

$l_{\mathrm{yy}}=\underset{1}{\overset{n}{\mathrm{\Σ}}}{(y_i-\stackrel{\‾}{y})}^2$

$l_{\mathrm{xy}}=\underset{1}{\overset{n}{\mathrm{\Σ}}}(x_i-\stackrel{\‾}{x})(y_i-\stackrel{\‾}{y})$

$b=\frac{\underset{1}{\overset{n}{\mathrm{\Σ}}}(x_i-\stackrel{\‾}{x})(y_i-\stackrel{\‾}{y})}{\underset{1}{\overset{n}{\mathrm{\Σ}}}{(x_i-\stackrel{\‾}{x})}^2}=\frac{l_{\mathrm{xy}}}{l_{\mathrm{xx}}}$

$a=\stackrel{\‾}{y}-b\stackrel{\‾}{x}$

In the formula Be test figure x _i, y _iMean value.

Its linear regression coeffficient is: $r=\frac{l_{\mathrm{xy}}}{\sqrt{l_{\mathrm{xx}}{l}_{\mathrm{yy}}}}$

Get by two groups of test figures and top computing formula:

b ₁＝95.885，a ₁＝209.1，r ₁＝0.999

b ₂＝96.275，a ₂＝208.03，r ₂＝0.999

Therefore, two groups of fuel blends are respectively based on the mixing ratio test model of specific inductive capacity:

y ₁＝95.885x ₁-209.1

y ₂＝96.275x ₂-208.03

Article two, the linear regression coeffficient of regression straight line: r levels off to 1, illustrate between the relative dielectric constant of the blending ratio of two groups of biodiesel fuel blends and biodiesel fuel blend to have significant linear relationship (seeing Fig. 3, Fig. 4 regression straight line figure), and with the established model C=96 ε of institute of the present invention _r-208.5 have good consistance.

3) prove the correctness of institute's established model, the relative dielectric constant values of the biodiesel fuel blend that two groups of tests are recorded are brought the established model C=96 ε of institute of the present invention into respectively _r-208.5, obtain mixing ratio by institute's established model test organisms diesel blended fuel, and the relative error of calculating and true value (see Table 3 and table 4), the relative error of the accurate ratio when being disposed with the biodiesel fuel blend by the blending ratio of the biodiesel fuel blend of institute established model test as can be seen is not more than 5.0%, shows the established model C=96 ε of institute of the present invention _r-208.5 can satisfy the measuring accuracy requirement, have good practicality.

Table 1 A group fuel blend relative dielectric constant value

Table 2 B group fuel blend relative dielectric constant value

The checking of table 3 fuel blend mixing ratio test model (A group)

Sequence number	Mixing ratio true value (%)	Dielectric constant values	Mixing ratio test value (%)	Error (%)
					??1	??5	??2.226	??5.196	??3.92
??2	??10	??2.281	??10.476	??4.76
					??3	??20	??2.373	??19.308	??-3.46
??4	??40	??2.590	??40.14	??0.35
					??5	??50	??2.690	??49.74	??-0.52

Sequence number	Mixing ratio true value (%)	Dielectric constant values	Mixing ratio test value (%)	Error (%)
					??6	??80	??3.010	??80.46	??0.58
??7	??100	??3.233	??100.90	??0.90

The checking of table 4 fuel blend mixing ratio test model (B group)

Sequence number	Mixing ratio true value (%)	Dielectric constant values	Mixing ratio test value (%)	Error (%)
					??1	??5	??2.222	??4.812	??-3.76
??2	??10	??2.271	??9.516	??-4.84
					??3	??20	??2.370	??19.020	??-4.90
??4	??40	??2.569	??38.124	??-4.69
					??5	??50	??2.670	??47.82	??-4.36
??6	??80	??2.983	??77.868	??-2.67
					??7	??100	??3.217	??100.332	??0.33

Claims (2)

1. method for detecting mixing ratios of biodiesel blended fuels, it is characterized in that: by the relative dielectric constant value of different mixing proportion biodiesel fuel blend is measured, analyze, determine the mapping relations between biodiesel mixing ratio and the relative dielectric constant, structure is based on the biodiesel mixing ratio test model of specific inductive capacity, by the measurement and the demarcation of specific inductive capacity, determine biodiesel fuel blend mixing ratio.

2. a kind of method for detecting mixing ratios of biodiesel blended fuels according to claim 1 is characterized in that: the test model of biodiesel fuel blend mixing ratio is C=96 ε _r-208.5, in the formula: ε _rFor relative dielectric constant value, the C of the fuel blend that records in real time is the mixing ratio of fuel blend.

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