Patent US4601587A successfully refreshed from Google Patents.
US4601587A
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Device and method for determining freezing points
Assignee: MATHIPRAKASAM B
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Filing: 1983-09-21
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Granted: 1986-07-22
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Expires: 2003-09-21
Abstract
Abstract A freezing point method and device (10) are disclosed. The method and device pertain to an inflection point technique for determining the freezing points of mixtures. In both the method and device (10), the mixture is cooled to a point below its anticipated freezing point and then warmed at a substantially linear rate. During the warming process, the rate of increase of temperature of the mixture is monitored by, for example, thermocouple (28) with the thermocouple output signal being amplified and differentiated by a differentiator (42). The rate of increase of temperature data are analyzed and a peak rate of increase of temperature is identified. In the preferred device (10) a computer (22) is utilized to analyze the rate of increase of temperature data following the warming process. Once the maximum rate of increase of temperature is identified, the corresponding temperature of the mixture is located and earmarked as being substantially equal to the freezing point of the mixture. In a preferred device (10), the computer (22), in addition to collecting the temperature and rate of change of temperature data, controls a programmable power supply (14) to provide a predetermined amount of cooling and warming current to thermoelectric modules (56).
Inventors
- 👤 Balakrishnan Mathiprakasam
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 15:45
CPC Classifications
G; G01; G01N; G01N25/00; G01N25/02; G01N25/04
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
160 words
A method for determining the freezing point of a mixture having an anticipated freezing point, comprising the following steps: (a) cooling the mixture to a temperature less than its anticipated freezing point; (b) controllably warming the mixture by actively controlling a net heat transfer thereto to increase the temperature of the mixture at a substantially constant rate during that time when the mixture is not undergoing a phase change; (c) identifying an instant of time when a peak rate of increase of temperature of the mixture occurs; and (d) determining the temperature of the mixture that existed at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said substantially constant rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 2
Independent Claim
160 words
A method for determining the freezing point of a mixture having an anticipated freezing point, comprising the following steps: (a) cooling the mixture to a temperature less than its anticipated freezing point; (b) controllably warming the mixture by actively controlling a net heat transfer thereto to increase the temperature of the mixture at a substantially constant rate during that time when the mixture is not undergoing a phase change; (c) identifying an instant of time when a peak rate of increase of temperature of the mixture occurs; and (d) determining the temperature of the mixture that existed at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said substantially constant rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 3
Dependent Claim
17 words
The method in accordance with claim 1, wherein the mixture is thermoelectrically warmed during said warming step.
Claim 4
Dependent Claim
26 words
The method in accordance with claim 2, wherein the mixture is thermoelectrically cooled to a temperature less than its anticipated freezing point during said cooling step.
Claim 5
Dependent Claim
57 words
The method in accordance with claim 3, wherein said identifying step comprises: (a) measuring the temperature of the mixture during said warming step; (b) determining a rate of increase of temperature of the mixture during said warming step; and (c) identifying said peak rate of increase of temperature of the mixture that occurs during said warming step.
Claim 6
Dependent Claim
28 words
The method in accordance with claim 1, wherein the mixture is a hydrocarbon mixture and said constant rate is between approximately 20 and 25 degrees centigrade per minute.
Claim 7
Dependent Claim
18 words
The method in accordance with claim 5, wherein the hydrocarbon mixture is thermoelectrically warmed during said warming step.
Claim 8
Dependent Claim
27 words
The method in accordance with claim 6, wherein the hydrocarbon mixture is thermoelectrically cooled to a temperature less than its anticipated freezing point during said cooling step.
Claim 9
Dependent Claim
60 words
The method in accordance with claim 7, wherein said identifying step comprises: (a) measuring the temperature of the hydrocarbon mixture during said warming step; (b) determining a rate of increase of temperature of the hydrocarbon mixture during said warming step; and (c) identifying said peak rate of increase of temperature of the hydrocarbon mixture that occurs during said warming step.
Claim 10
Dependent Claim
32 words
The method in accordance with claim 1, further comprising the following step between said cooling and warming steps: maintaining the temperature of the mixture substantially constant for a predetermined period of time.
Claim 11
Dependent Claim
17 words
The method in accordance with claim 9, wherein the mixture is thermoelectrically warmed during said warming step.
Claim 12
Dependent Claim
26 words
The method in accordance with claim 10, wherein the mixture is thermoelectrically cooled to a temperature less than its anticipated freezing point during said cooling step.
Claim 13
Dependent Claim
57 words
The method in accordance with claim 11, wherein said identifying step comprises: (a) measuring the temperature of the mixture during said warming step; (b) determining a rate of increase of temperature of the mixture during said warming step; and (c) identifying said peak rate of increase of temperature of the mixture that occurs during said warming step.
Claim 14
Dependent Claim
33 words
The method in accordance with claim 5, further comprising the following step between said cooling and warming steps: maintaining the temperature of the hydrocarbon mixture substantially constant for a predetermined period of time.
Claim 15
Dependent Claim
18 words
The method in accordance with claim 13, wherein the hydrocarbon mixture is thermoelectrically warmed during said warming step.
Claim 16
Dependent Claim
27 words
The method in accordance with claim 14, wherein the hydrocarbon mixture is thermoelectrically cooled to a temperature less than its anticipated freezing point during said cooling step.
Claim 17
Dependent Claim
60 words
The method in accordance with claim 15, wherein said identifying step comprises: (a) measuring the temperature of the hydrocarbon mixture during said warming step; (b) determining a rate of increase of temperature of the hydrocarbon mixture during said warming step; and (c) identifying said peak rate of increase of temperature of the hydrocarbon mixture that occurs during said warming step.
Claim 18
Independent Claim
244 words
A method for determining the freezing point of a hydrocarbon mixture having an anticipated freezing point, comprising the following steps: (a) thermoelectrically cooling the hydrocarbon mixture to a temperature less than its anticipated freezing point; (b) stabilizing the hydrocarbon mixture by maintaining the temperature of the cooled hydrocarbon mixture substantially constant for a predetermined period of time; (c) thermoelectrically warming the cooled hydrocarbon mixture by actively controlling a net heat transfer thereto to increase the temperature of the hydrocarbon mixture at a rate between approximately 20 and 25 degrees centigrade per minute during that time when the hydrocarbon mixture is not undergoing a phase change; (d) measuring the temperature of the hydrocarbon mixture during said warming step; (e) determining a rate of increase of temperature of the hydrocarbon mixture during said warming step; (f) identifying a peak rate of increase of temperature of the hydrocarbon mixture that occurs during said warming step; (g) identifying an instant of time when said peak rate of increase of temperature of the hydrocarbon mixture occured; and (h) determining the temperature of the hydrocarbon mixture that existed at said instant of time, wherein this temperature is substantially equal to the freezing point of the hydrocarbon mixture, wherein said rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 19
Independent Claim
244 words
A method for determining the freezing point of a hydrocarbon mixture having an anticipated freezing point, comprising the following steps: (a) thermoelectrically cooling the hydrocarbon mixture to a temperature less than its anticipated freezing point; (b) stabilizing the hydrocarbon mixture by maintaining the temperature of the cooled hydrocarbon mixture substantially constant for a predetermined period of time; (c) thermoelectrically warming the cooled hydrocarbon mixture by actively controlling a net heat transfer thereto to increase the temperature of the hydrocarbon mixture at a rate between approximately 20 and 25 degrees centigrade per minute during that time when the hydrocarbon mixture is not undergoing a phase change; (d) measuring the temperature of the hydrocarbon mixture during said warming step; (e) determining a rate of increase of temperature of the hydrocarbon mixture during said warming step; (f) identifying a peak rate of increase of temperature of the hydrocarbon mixture that occurs during said warming step; (g) identifying an instant of time when said peak rate of increase of temperature of the hydrocarbon mixture occured; and (h) determining the temperature of the hydrocarbon mixture that existed at said instant of time, wherein this temperature is substantially equal to the freezing point of the hydrocarbon mixture, wherein said rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 20
Dependent Claim
65 words
The method in accordance with claim 17, wherein said temperature measuring step comprises placing a temperature transducer in thermal communication with the hydrocarbon mixture, said temperature transducer having an electrical transducer output signal representative of the temperature of the hydrocarbon mixture and wherein said rate determining step comprises electronically differentiating said transducer output signal with respect to time to generate an electrical differentiator output signal.
Claim 21
Dependent Claim
32 words
The method in accordance with claim 18, wherein said peak identifying step comprises electronically analyzing said differentiator output signal to locate said peak rate of increase of temperature of the hydrocarbon mixture.
Claim 22
Dependent Claim
15 words
The method in accordance with claim 19, wherein the hydrocarbon mixture is an aviation fuel.
Claim 23
Independent Claim
247 words
A device for determining the freezing point of a mixture having an anticipated freezing point, comprising: (a) means for cooling the mixture to a temperature less than its anticipated freezing point, said cooling means being in thermal communication with the mixture; (b) means for controllably warming the mixture by actively controlling a net heat transfer thereto to increase the temperature of the mixture at a substantially constant rate during that time when the mixture is not undergoing a phase change, said warming means being in thermal communication with the mixture; (c) means for measuring the temperature of the mixture, said temperature measuring means being in operative proximity of the mixture; (d) rate sensing means operatively disposed to monitor the mixture for providing a rate signal indicative of the rate of change of temperature of the mixture; and (e) means operatively connected to said temperature measuring means and to said rate sensing means for determining an instant of time when said rate of increase of temperature attains a maximum and for providing a freezing point test output signal indicative of the temperature of the mixture at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said substantially constant rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 24
Independent Claim
247 words
A device for determining the freezing point of a mixture having an anticipated freezing point, comprising: (a) means for cooling the mixture to a temperature less than its anticipated freezing point, said cooling means being in thermal communication with the mixture; (b) means for controllably warming the mixture by actively controlling a net heat transfer thereto to increase the temperature of the mixture at a substantially constant rate during that time when the mixture is not undergoing a phase change, said warming means being in thermal communication with the mixture; (c) means for measuring the temperature of the mixture, said temperature measuring means being in operative proximity of the mixture; (d) rate sensing means operatively disposed to monitor the mixture for providing a rate signal indicative of the rate of change of temperature of the mixture; and (e) means operatively connected to said temperature measuring means and to said rate sensing means for determining an instant of time when said rate of increase of temperature attains a maximum and for providing a freezing point test output signal indicative of the temperature of the mixture at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said substantially constant rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 25
Dependent Claim
18 words
The device in accordance with claim 21, wherein said warming means comprises means for thermoelectrically warming the mixture.
Claim 26
Dependent Claim
18 words
The device in accordance with claim 22, wherein said cooling means comprises means for thermoelectrically cooling the mixture.
Claim 27
Dependent Claim
59 words
The device in accordance with claim 23, wherein said temperature measuring means provides a first temperature signal and a second temperature signal, said temperature signals being indicative of the temperature of the mixture; and said first temperature signal is received by said rate sensing means and said second temperature signal is received by said instant of time determining means.
Claim 28
Dependent Claim
29 words
The device in accordance with claim 24, wherein said first and second temperature signals are of analog nature and said rate sensing means comprises an analog time differentiation circuit.
Claim 29
Dependent Claim
18 words
The device in accordance with claim 25, wherein said instant of time determining means comprises a digital computer.
Claim 30
Dependent Claim
15 words
The device in accordance with claim 26, wherein said temperature measuring means comprises a thermocouple.
Claim 31
Dependent Claim
28 words
The device in accordance with claim 21, wherein the mixture is a hydrocarbon mixture and said constant rate is between approximately 20 and 25 degrees centigrade per minute.
Claim 32
Dependent Claim
19 words
The device in accordance with claim 28, wherein said warming means comprises means for thermoelectrically warming the hydrocarbon mixture.
Claim 33
Dependent Claim
19 words
The device in accordance with claim 29, wherein said cooling means comprises means for thermoelectrically cooling the hydrocarbon mixture.
Claim 34
Dependent Claim
60 words
The device in accordance with claim 30, wherein said temperature measuring means provides a first temperature signal and a second temperature signal, said temperature signals being indicative of the temperature of the hydrocarbon mixture; and said first temperature signal is received by said rate sensing means and said second temperature signal is received by said instant of time determining means.
Claim 35
Dependent Claim
29 words
The device in accordance with claim 31, wherein said first and second temperature signals are of analog nature and said rate sensing means comprises an analog time differentiation circuit.
Claim 36
Dependent Claim
18 words
The device in accordance with claim 32, wherein said instant of time determining means comprises a digital computer.
Claim 37
Dependent Claim
15 words
The device in accordance with claim 33, wherein said temperature measuring means comprises a thermocouple.
Claim 38
Dependent Claim
44 words
The device in accordance with claim 21, further comprising means for maintaining the temperature of the mixture substantially constant for a predetermined period of time at a temperature less than its anticipated freezing point, said maintaining means being in thermal communication with the mixture.
Claim 39
Dependent Claim
18 words
The device in accordance with claim 35, wherein said warming means comprises means for thermoelectrically warming the mixture.
Claim 40
Dependent Claim
18 words
The device in accordance with claim 36, wherein said cooling means comprises means for thermoelectrically cooling the mixture.
Claim 41
Dependent Claim
59 words
The device in accordance with claim 37, wherein said temperature measuring means provides a first temperature signal and a second temperature signal, said temperature signals being indicative of the temperature of the mixture; and said first temperature signal is received by said rate sensing means and said second temperature signal is received by said instant of time determining means.
Claim 42
Dependent Claim
29 words
The device in accordance with claim 38, wherein said first and second temperature signals are of analog nature and said rate sensing means comprises an analog time differentiation circuit.
Claim 43
Dependent Claim
18 words
The device in accordance with claim 39, wherein said instant of time determining means comprises a digital computer.
Claim 44
Dependent Claim
15 words
The device in accordance with claim 40, wherein said temperature measuring means comprises a thermocouple.
Claim 45
Dependent Claim
46 words
The device in accordance with claim 28, further comprising means for maintaining the temperature of the hydrocarbon mixture substantially constant for a predetermined period of time at a temperature less than its anticipated freezing point, said holding means being in thermal communication with the hydrocarbon mixture.
Claim 46
Dependent Claim
19 words
The device in accordance with claim 42, wherein sid warming means comprises means for thermoelectrically warming the hydrocarbon mixture.
Claim 47
Dependent Claim
19 words
The device in accordance with claim 43, wherein said cooling means comprises means for thermoelectrically cooling the hydrocarbon mixture.
Claim 48
Dependent Claim
60 words
The device in accordance with claim 44, wherein said temperature measuring means provides a first temperature signal and a second temperature signal, said temperature signals being indicative of the temperature of the hydrocarbon mixture; and said first temperature signal is received by said rate sensing means and said second temperature signal is received by said instant of time determining means.
Claim 49
Dependent Claim
29 words
The device in accordance with claim 45, wherein said first and second temperature signals are of analog nature and said rate sensing means comprises an analog time differentiation circuit.
Claim 50
Dependent Claim
18 words
The device in accordance with claim 46, wherein said instant of time determining means comprises a digital computer.
Claim 51
Dependent Claim
15 words
The device in accordance with claim 47, wherein said temperature measuring means comprises a thermocouple.
Claim 52
Independent Claim
325 words
A device for measuring the freezing point of a hydrocarbon mixture having an anticipated freezing point, comprising: (a) thermoelectrical means for cooling the hydrocarbon mixture to a cool temperature less than its anticipated freezing point, said cooling means being in heat conductive engagement with the hydrocarbon mixture; (b) thermoelectrical means for maintaining the hydrocarbon mixture at said cool temperature for a predetermined period of time to stabilize the hydrocarbon mixture, said thermoelectrical maintaining means being in heat conductive engagement with the hydrocarbon mixture; (c) thermoelectrical means for controllably warming the hydrocarbon mixture by actively controlling the net heat transfer thereto to increase the temperature of the hydrocarbon mixture from said cool temperature to a warm temperature at a rate of approximately 20 to 25 degrees centigrade per minute during that time when the hydrocarbon mixture is not undergoing a phase change, said thermoelectrical warming means being in heat conductive engagement with the hydrocarbon mixture; (d) a thermocouple in heat conductive engagement with the hydrocarbon mixture, said thermocouple providing a first thermocouple output signal and a second thermocouple output signal; (e) differentiation means for providing a rate signal indicative of the rate of change of temperature of the hydrocarbon mixture as it is being warmed, said differentiation means receiving said first thermocouple output signal; and (f) a digital computer adapted to receive said second thermocouple output signal and said rate signal, said digital computer determining an instant of time when the rate of increase of temperature obtains a maximum and providing a freezing point test output signal indicative of the temperature of the hydrocarbon mixture at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 53
Independent Claim
325 words
A device for measuring the freezing point of a hydrocarbon mixture having an anticipated freezing point, comprising: (a) thermoelectrical means for cooling the hydrocarbon mixture to a cool temperature less than its anticipated freezing point, said cooling means being in heat conductive engagement with the hydrocarbon mixture; (b) thermoelectrical means for maintaining the hydrocarbon mixture at said cool temperature for a predetermined period of time to stabilize the hydrocarbon mixture, said thermoelectrical maintaining means being in heat conductive engagement with the hydrocarbon mixture; (c) thermoelectrical means for controllably warming the hydrocarbon mixture by actively controlling the net heat transfer thereto to increase the temperature of the hydrocarbon mixture from said cool temperature to a warm temperature at a rate of approximately 20 to 25 degrees centigrade per minute during that time when the hydrocarbon mixture is not undergoing a phase change, said thermoelectrical warming means being in heat conductive engagement with the hydrocarbon mixture; (d) a thermocouple in heat conductive engagement with the hydrocarbon mixture, said thermocouple providing a first thermocouple output signal and a second thermocouple output signal; (e) differentiation means for providing a rate signal indicative of the rate of change of temperature of the hydrocarbon mixture as it is being warmed, said differentiation means receiving said first thermocouple output signal; and (f) a digital computer adapted to receive said second thermocouple output signal and said rate signal, said digital computer determining an instant of time when the rate of increase of temperature obtains a maximum and providing a freezing point test output signal indicative of the temperature of the hydrocarbon mixture at said instant of time, wherein this temperature is substantially equal to the freezing point of the mixture, wherein said rate of increase of temperature is selected such that regardless of the freezing point of the mixture said rate of increase of temperature is sufficiently high to render identifiable said instant of time and is sufficiently low to provide acceptable accuracy.
Claim 54
Dependent Claim
15 words
The device in accordance with claim 49, wherein said hydrocarbon mixture is an aviation fuel.
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