Biodiesel is inherently prone to degradation in an oxidizing environment as compared to petrodiesel because of its chemical composition. Biodiesel has long-chain hydrocarbons (e.g., fatty acids) that vary widely depending on feedstock sources. In particular, both a number of total carbon atoms and a number of carbon-to-carbon double bonds vary in biodiesel depending on the feedstock sources. In an oxidizing environment, oxygen attaches to the carbon-to-carbon double bonds to undesirably form primary and secondary oxidation products including aldehydes, alcohols, shorter chain carboxylic acids (formic and acetic), and high weight molecular oligomers (polymers). One measure of the degradation of the biodiesel is a total acid number associated with the biodiesel.
Accordingly, the inventors herein have recognized a need for a system and a method for determining a total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel.
A method for determining a total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel in accordance with an exemplary embodiment is provided. The method includes receiving an oscillatory signal at an inductance-capacitance-resistance circuit. The circuit has a sensing element fluidly communicating with the mixture of biodiesel and petrodiesel. The method further includes generating a resonant current at a resonant frequency utilizing the circuit in response to the oscillatory signal. The method further includes determining a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current, utilizing a microprocessor. The method further includes determining a concentration value indicating a concentration of the biodiesel in the mixture based on an amplitude of the resonant current and the dielectric constant value, utilizing the microprocessor. The method further includes determining the total acid number associated with the biodiesel in the mixture based on the amplitude of the resonant current and the concentration value, utilizing the microprocessor. The method further includes storing the total acid number in a memory device, utilizing the microprocessor.
A system for determining a total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel in accordance with another exemplary embodiment is provided. The system includes an inductance-capacitance-resistance circuit configured to receive an oscillatory signal. The circuit has a sensing element fluidly communicating with the mixture of biodiesel and petrodiesel. The circuit is further configured to generate a resonant current at a resonant frequency in response to the oscillatory signal. The system further includes a microprocessor operatively associated with the circuit. The microprocessor is configured to determine a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current. The microprocessor is further configured to determine a concentration value indicating a concentration of the biodiesel in the mixture based on an amplitude of the resonant current and the dielectric constant value. The microprocessor is further configured to determine the total acid number associated with the biodiesel in the mixture based on the amplitude of the resonant current and the concentration value. The microprocessor is further configured to store the total acid number in a memory device.
A method for determining a total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel in accordance with another exemplary embodiment is provided. The method includes receiving an oscillatory signal at an inductance-capacitance-resistance circuit. The circuit has a sensing element fluidly communicating with the mixture of biodiesel and petrodiesel. The method further includes generating a resonant current at a resonant frequency utilizing the circuit in response to the oscillatory signal. The method further includes determining a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current, utilizing a microprocessor. The method further includes determining a concentration value indicating a concentration of the biodiesel in the mixture based on an amplitude of the resonant current and the dielectric constant value, utilizing the microprocessor. The method further includes determining the total acid number associated with the biodiesel in the mixture based on the dielectric constant value and the concentration value, utilizing the microprocessor. The method further includes storing the total acid number in a memory device, utilizing the microprocessor.
A system for determining a total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel in accordance with another exemplary embodiment is provided. The system includes an inductance-capacitance-resistance circuit configured to receive an oscillatory signal. The circuit has a sensing element fluid by communicating with the mixture of biodiesel and petrodiesel. The circuit is further configured to generate a resonant current at a resonant frequency in response to the oscillatory signal. The system further includes a microprocessor operatively associated with the circuit. The microprocessor is configured to determine a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current. The microprocessor is further configured to determine a concentration, value indicating a concentration of the biodiesel in the mixture based on an amplitude of the resonant current and the dielectric constant value. The microprocessor is further configured to determine the total acid number associated with the biodiesel in the mixture based on the dielectric constant value and the concentration value. The microprocessor is farther configured to store the total acid number in a memory device.
Biodiesel can be obtained from several different source feedstocks. For example, biodiesel can be obtained from soy feedstock, cottonseed feedstock, and poultry fat feedstock, further, referring to
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The phase lock loop circuit 24 is provided to generate an oscillatory signal that is received by the LCR circuit 20. The phase lock loop circuit 24 includes a phase lock loop microchip 60, a buffer 62, and a phase inverter 64. The phase lock loop circuit 24 receives signals from both the current-to-voltage converter 23 and a phase inverter 64. The phase lock loop circuit 24 outputs the oscillatory signal that is transmitted through the buffer 62 to a node 66. From the node 66, the oscillatory signal propagates through the capacitor 22 to the LCR circuit 20 to stimulate the LCR circuit 20. Further, from the node 66 the oscillatory signal propagates to the phase inverter 64. The phase inverter 64 modifies a phase of the oscillatory signal which is received by the phase lock loop microchip 60. During operation, the phase lock loop microchip 60 generates the oscillatory signal that is received by the LCR circuit 20 to induce the LCR circuit 20 to output a resonant current at a resonant frequency. Further, the phase lock loop microchip 60 sends a message to the microprocessor 30 having data indicating a resonant frequency of the output oscillatory signal from the phase lock loop circuit 24, that is further indicative of a resonant frequency of the resonant current of the LCR circuit 20.
It should be noted that in an alternative embodiment of the system 10, the phase lock loop circuit 24 could be replaced with a signal generator (not shown) that receives a signal from the current-to-voltage converter 23 and adjusts an output oscillatory signal is received by the LCR circuit 20 based on the signal from the current-to-voltage converter 23,
A node 27 is electrically coupled to both the capacitor 22 and the LCR circuit 20. A resistor 25 is electrically coupled between the node 27 and electrical ground. The resistor 25 is provided to reset a mean value of the oscillatory signal from the phase lock loop circuit 24 to a ground level.
The AC/DC voltage converter 26 is provided to receive the voltage signal from the current-to-voltage converter 23 and to generate a DC voltage signal indicative of an amplitude of the received voltage signal. The AC/DC voltage converter 26 is electrically coupled between the node 29 and the DC amplifier 28,
The DC amplifier 28 is provided to amplify the DC voltage signal received from the AC/DC voltage converter 26 and to send the amplified DC voltage signal to the microprocessor 30. The DC amplifier 28 is electrically coupled between the AC/DC voltage converter 26 and the microprocessor 30.
The microprocessor 30 is provided to determine a concentration value indicative of a concentration of biodiesel in a mixture of biodiesel and petrodiesel. In particular, the microprocessor 30 is configured to execute software algorithms to determine the concentration of biodiesel in the mixture based on (i) a dielectric constant associated with the mixture, (ii) an amplitude of the resonant current of the LCR circuit 20, or (iii) both the dielectric constant associated with the mixture and the amplitude of the resonant current of the LCR circuit 20, as will be explained in greater detail below. The microprocessor 30 is further configured to determine a total acid number associated with biodiesel within the mixture, as will be explained in greater detail below. The microprocessor 30 is further configured to store the total acid number in the memory device 32. As shown, the microprocessor 30 is electrically coupled to the DC amplifier 28, the memory device 32, and the phase lock loop microchip 60.
Before providing a detailed explanation of the methodology for determining a concentration of biodiesel in a mixture of biodiesel and petrodiesel and a total acid number associated with the biodiesel, an explanation of the physical properties that can be utilized to determine the biodiesel concentration and the total acid number will be discussed.
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The curve 96 represents a delta dielectric constant associated with a mixture of fresh (e.g., non-oxidized) biodiesel and petrodiesel versus a biodiesel concentration. The delta dielectric constant is obtained by subtracting a dielectric constant associated with pure petrodiesel from a dielectric constant associated with a mixture of biodiesel and petrodiesel. The curve 98 represents a delta dielectric constant associated with a mixture of baked (e.g., oxidized) biodiesel and petrodiesel versus a biodiesel concentration. As shown by curves 96, 98, the relationship between the delta dielectric constant and the biodiesel concentration can vary based upon whether the biodiesel is oxidized or non-oxidized.
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At step 230, the phase lock loop circuit 24 generates an oscillatory signal that is received by the LOR circuit 20, based on a feedback signal, and a first voltage signal received from the current-to-voltage converter 23.
At step 232, the LCR circuit 20 generates a resonant current at a resonant frequency that is received by the current-to-voltage converter 23 in response to the oscillatory signal. The LCR circuit 20 has the sensing element 42 fluidly communicating with the mixture of biodiesel and petrodiesel.
At step 234, the current-to-voltage converter 23 generates the first voltage signal in response to the resonant current that is received by both the phase lock loop circuit 24 and the AC/DC voltage converter 26.
At step 236, the AC/DC voltage converter 26 generates a second voltage signal in response to the first voltage signal.
At step 238, the DC amplifier 28 amplifies the second voltage signal to obtain a third voltage signal that is received by the microprocessor 30. The third signal is indicative of an amplitude of the resonant current.
At step 240, the microprocessor 30 determines a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a dielectric constant value in the lookup table based on the resonant frequency of the resonant current.
At step 242, the microprocessor 30 determines an index value utilizing the following equation: index value=((amplitude of resonant current−first predetermined value)2/(dielectric constant value−second predetermined value)). The first predetermined value corresponds to amplitude of a resonant current when pure petrodiesel is being measured. The second predetermined value corresponds to a dielectric constant value when pure petrodiesel is being measured. It should be noted that the value (amplitude of resonant current−first predetermined value) corresponds to the delta resonant current discussed above. If should be further noted that the value (dielectric constant value−second predetermined value) corresponds to the delta dielectric constant discussed above.
AC step 244, the microprocessor 30 determines a concentration value indicating a concentration of the biodiesel in the mixture based on the index value. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a concentration value in the lookup table based on the index value.
At step 246, the microprocessor 30 determines a delta resonant current value utilizing the following equation: delta resonant current value=amplitude of resonant current−first predetermined value.
At step 248, the microprocessor 30 determines the total acid number associated with the biodiesel in the mixture based on the delta resonant current value and the concentration value. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a total acid number in the lookup table based on the delta resonant current value and the concentration value.
At step 250, the microprocessor 30 stores the total acid number in the memory device 32. After step 250, the method is exited.
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At step 270, the phase lock loop circuit 24 generates an oscillatory signal that is received by the LCR circuit 20, based on a feedback signal, and a first voltage signal received from the current-to-voltage converter 23.
At step 272, the LCR circuit 20 generates a resonant current at a resonant frequency that is received by the current-to-voltage converter 23 in response to the oscillatory signal. The LCR circuit 20 has the sensing element 42 fluidly communicating with the mixture of biodiesel and petrodiesel.
At step 274, the current-to-voltage converter 23 generates the first voltage signal in response to the resonant current that is received by both the phase lock loop circuit 24 and the AC/DC voltage converter 26.
At step 276, the AC/DC voltage converter 26 generates a second voltage signal in response to the first voltage signal.
At step 278, the DC amplifier 28 amplifies the second voltage signal to obtain a third voltage signal that is received by tire microprocessor 30. The third signal is indicative of an amplitude of the resonant current.
At step 280, the microprocessor 30 determines a dielectric constant value indicating a dielectric constant associated with the biodiesel in the mixture based on the resonant frequency of the resonant current. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a dielectric constant value in the lookup table based on the resonant frequency of the resonant current.
At step 282, the microprocessor 30 determines an index value utilizing the following equation: index value=((amplitude of resonant current−first predetermined value)2/(dielectric constant value−second predetermined value)). The first predetermined value corresponds to amplitude of a resonant current when pure petrodiesel is being measured. The second predetermined value corresponds to a dielectric constant value when pure petrodiesel is being measured. It should he noted that the value (amplitude of resonant current−first predetermined value) corresponds to the delta resonant current discussed above. It should be further noted that the value (dielectric constant value−second predetermined value) corresponds to the delta dielectric constant discussed above.
At step 284, the microprocessor 30 determines a concentration value indicating a concentration of the biodiesel in the mixture based on the index value. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a concentration value in the lookup table based on the index value.
At step 286, the microprocessor 30 determines a delta dielectric constant value utilizing the following equation: delta, dielectric constant value=dielectric constant value−second predetermined value.
At step 288, the microprocessor 30 determines the total acid number associated with the biodiesel in the mixture based on the delta dielectric constant value and the concentration value. For example, the microprocessor 30 can utilize a lookup table stored in the memory device 32 and access a total acid number in the lookup table based on the delta dielectric constant and the concentration value.
At step 290, the microprocessor 30 stores the total acid number in the memory device 32. After step 290, the method is exited.
The systems and methods for determining a concentration of biodiesel in a mixture of biodiesel and petrodiesel represent a substantial advantage ever other systems and methods. In particular, the systems and methods provide a technical effect of accurately measuring the total acid number associated with biodiesel in a mixture of biodiesel and petrodiesel, utilizing a relatively small inexpensive sensing element. Further, the system and methods are able to accurately measure the total acid number in the mixture of biodiesel and petrodiesel irrespective of moisture impurities and insoluble components in the mixture.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed for carrying this invention, but that the invention will include all embodiments failing within the scope of the appended claims. Moreover, the use of the terms, first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.