WO1999031492A1 - Method and device for determining the freezing point - Google Patents
Method and device for determining the freezing point Download PDFInfo
- Publication number
- WO1999031492A1 WO1999031492A1 PCT/SE1998/002144 SE9802144W WO9931492A1 WO 1999031492 A1 WO1999031492 A1 WO 1999031492A1 SE 9802144 W SE9802144 W SE 9802144W WO 9931492 A1 WO9931492 A1 WO 9931492A1
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- WO
- WIPO (PCT)
- Prior art keywords
- sample
- liquid
- container
- freezing
- point
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
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Classifications
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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
- G01N25/02—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering
- G01N25/04—Investigating or analyzing materials by the use of thermal means by investigating changes of state or changes of phase; by investigating sintering of melting point; of freezing point; of softening point
Definitions
- the spreading of salt has disadvantages, however.
- the environment on and around the road can be damaged by salt, at least in larger quantities.
- Spreading salt also involves a large expense, and vehicles that travel on roads on which salt is spread are affected by rust.
- the liquid On one side the liquid is in thermal contact with the Peltier element. By conducting current in one direction through the element the liquid is cooled, and when the direction is reversed, the liquid is heated. A number of cycles must be run in order to determine the freezing point.
- the Peltier element is in itself a device for measurement of the temperature through the use of special characteristics of the Peltier element. The ambient temperature is also measured.
- FIG 1 is a schematic perspective front view showing a device according to the invention before a process of measurement
- FIG 2 is a side view partially in section of the device in FIG 1 during a process of measurement
- FIG 3 is a diagram that schematically shows the temperature in a sample during a process of measurement.
- Measuring assembly 18 is comprised of a cooling device 10 and a heating device 11.
- a Peltier element 19 serves both as cooling and heating device.
- the Peltier element is located centrally in the bottom on a container 13 formed as a recess in the cylindrical body.
- Control plate 17 functions so that liquid, which splashes up from the road surface, is led to container 13.
- Control plate 17 includes a membrane of flexible sheet material, for example rubber, that constitutes a barrier 20 during a measurement (see FIG 2).
- Strut 21 connects bottom plate 16 with control plate 17.
- the flexible sheet material is firmly braced against control plate 17 with a locking ring 22 (see FIG 2).
- the container is cleaned between measurements with a cleaning device 15 so that a new measurement will relate to a new liquid, for example from a different part of the road.
- Cleaning device 15 can contain a nozzle or similar for compressed air directed toward the container. The nozzle is connected with a source of compressed air on the vehicle.
- FIG 2 shows a design of an apparatus according to the invention during an ongoing process of measurement.
- Barrier 20 has been set against container 13, so that liquid collected therein cannot disperse. At the same time new liquid is prevented from coming into the container.
- the barrier in the form of the flexible membrane is extended by filling the space behind the membrane with compressed air.
- a surface on Peltier element 19 is in thermal connection with container 13, suitably by constituting part of the bottom of the container.
- a control device 14 connected with the Peltier element is designed to provide electrical current to the Peltier-element in this position, so that its upper side is first warmed up in preparation for a measurement.
- Control device 14 can be designed as a circuit card separated from the measurement device itself.
- a heat absorbent body 23, for example of copper, is also in contact with the Peltier element.
- time t is on the x-axis and temperature T on the y-axis.
- the surrounding temperature is suitably measured with a measurement sensor separately connected with the control device.
- the surrounding temperature is marked at T s .
- the control device is automatically set so that a suitable level of power is supplied to the Peltier element.
- the measurement is started with a brief heating phase, which is shown in the curve in FIG 3 as a continuously rising temperature value.
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
A method and a device for measurement of the freezing point, whereby a cooling device (10) and a heating device (11) are provided in a measuring assembly (18) for repeated cooling down and heating, respectively, of a sample of liquid from a road surface to ice and warmed up again to liquid, and measuring means are provided for continual measuring of the temperature of the sample, so that the sample's freezing point can be determined by registration of the temperature change. A container (13) is provided on a vehicle for collection of a sample of liquid from the road surface. The cooling device (10) and heating device (11) are operatively connected to a control device (14) for repeated cooling of the sample of liquid to ice and warming of the ice to liquid form, and for continual measurement of the sample temperature, and the container (13) comprises dispensing means (15) to automatically empty the container (13) upon completed determination of the sample's freezing point.
Description
METHOD AND DEVICE FOR DETERMINING THE FREEZING POINT.
Technical Field of the Invention
The invention concerns a method and device for measurement of the freezing point, whereby a sample of liquid from a road surface is repeatedly frozen to ice and warmed up again to liquid form while the temperature in the sample is continually measured. The freezing point of the sample can be determined by registration of the temperature change.
State of the Art
In order to minimize the risk of accidents in connection with slick road surfaces, the possibility of lowering the freezing point of water with the aid of salt is exploited. When there is a risk of ice formation or accumulation of snow slush and similar on the road surface, salt is spread over the road surface so that ice and snow slush melt and can run off.
The spreading of salt has disadvantages, however. The environment on and around the road can be damaged by salt, at least in larger quantities. Spreading salt also involves a large expense, and vehicles that travel on roads on which salt is spread are affected by rust.
It is for the above reasons, among others, desirable to minimize the amount of salt that is spread. By measuring the salt content or the freezing point in the liquid film on a road surface, the requirement to add additional salt can be determined. According to a method currently used to achieve such a measurement, liquid is continually collected from the road surface in stationary measurement equipment arrayed on or in connection with the road surface. A sample in form of a certain amount of liquid from the road surface is exposed to a sensor. The liquid is cooled so that it freezes, after which the ice that is formed is melted. The procedure is repeated continuously. The temperature of the sample is measured continuously.
In SE 464595 a method of using a Peltier element for determination of the freezing point of a liquid is shown and described. On one side the liquid is in thermal contact with the Peltier element. By conducting current in one direction through the element the liquid is cooled, and when the direction is reversed, the liquid is heated. A number of cycles must be run in order to determine the freezing point. The Peltier element is in itself a device for measurement of the temperature through the use of special characteristics of the Peltier element. The ambient temperature is also measured.
During the cooling down phase the measured temperature value will show a discontinuity which corresponds to the freezing point of the liquid. Certain standard values for cooling and warming effects are automatically assigned, after which the measured temperature of the surroundings and the freezing point affect the power supply.
This known system for measurement of the freezing point and salt content functions well and gives a good view of local conditions and the need for further addition of salt. On the other hand there is no possibility to collect information on salt content across larger geographical areas. There are also problems in carrying out measurements limited in time of the freezing point in liquid on a road surface, since liquid is added and runs off continuously.
The Invention in Summary
One object of the invention is to improve the possibilities of gathering data on salt content across larger geographical areas. Another object is to eliminate problems which are present with known technology regarding measurements of the freezing point that are limited in time.
The objectives given above are achieved through the invention having gained the special features indicated in the independent patent claims below. Further objectives and advantages of the invention can be seen from the following description, drawings, and dependent patent claims.
Brief Description of the Drawings
The invention will now be described in more detail with the aid of examplary embodiments with reference to attached drawings on which
FIG 1 is a schematic perspective front view showing a device according to the invention before a process of measurement, FIG 2 is a side view partially in section of the device in FIG 1 during a process of measurement, and FIG 3 is a diagram that schematically shows the temperature in a sample during a process of measurement.
Description
The device shown in FIG 1 comprises a bottom plate 16 and a control plate 17 connected to it. On bottom plate 16 a measuring assembly 18 in form of a cylindrical body is located. The whole device according to FIG 1 is intended to be assembled on the underside of a vehicle in association with a wheel of the vehicle, so that liquid from a wet road surface splashes up on the device when the vehicle is in motion.
Measuring assembly 18 is comprised of a cooling device 10 and a heating device 11. According to a preferred design, a Peltier element 19 serves both as cooling and heating device. The Peltier element is located centrally in the bottom on a container 13 formed as a recess in the cylindrical body. Control plate 17 functions so that liquid, which splashes up from the road surface, is led to container 13. Control plate 17 includes a membrane of flexible sheet material, for example rubber, that constitutes a barrier 20 during a measurement (see FIG 2). Strut 21 connects bottom plate 16 with control plate 17. The flexible sheet material is firmly braced against control plate 17 with a locking ring 22 (see FIG 2). The container is cleaned between measurements with a cleaning device 15 so that a new measurement will relate to a new liquid, for example from a different part of the road. Cleaning device 15 can contain a nozzle or
similar for compressed air directed toward the container. The nozzle is connected with a source of compressed air on the vehicle.
FIG 2 shows a design of an apparatus according to the invention during an ongoing process of measurement. Barrier 20 has been set against container 13, so that liquid collected therein cannot disperse. At the same time new liquid is prevented from coming into the container. In the design shown the barrier in the form of the flexible membrane is extended by filling the space behind the membrane with compressed air.
A surface on Peltier element 19 is in thermal connection with container 13, suitably by constituting part of the bottom of the container. A control device 14 connected with the Peltier element is designed to provide electrical current to the Peltier-element in this position, so that its upper side is first warmed up in preparation for a measurement. Control device 14 can be designed as a circuit card separated from the measurement device itself. A heat absorbent body 23, for example of copper, is also in contact with the Peltier element.
An example of a measurement can be seen in FIG 3. In the diagram time t is on the x-axis and temperature T on the y-axis. In order to minimize the time of the measurement, the surrounding temperature is suitably measured with a measurement sensor separately connected with the control device. The surrounding temperature is marked at Ts. Because the surrounding temperature is already known at the start of the measurement, the control device is automatically set so that a suitable level of power is supplied to the Peltier element. The measurement is started with a brief heating phase, which is shown in the curve in FIG 3 as a continuously rising temperature value.
At a certain temperature the measurement enters a cooling phase during which the liquid in the container is cooled down. At a certain temperature the liquid begins to change into a form of ice, which leads to the release of heat. This can be seen in the curve, which climbs sharply. When the temperature approaches the freezing point of the liquid, the temperature increases by a step and then remains unchanged during an interval of time
that is marked in the diagram with tF. This later discontinuity is identified by the control device as the freezing point of the liquid when the temperature is TF. A display unit (not shown) connected with control device 14 indicates the current temperature to the driver of the vehicle. A corresponding temperature value can also be stored in a memory unit (not shown) for later review and collection of statistics.
Claims
1. A method for measurement of the freezing point, whereby a sample of liquid from a road surface is repeatedly frozen to ice and warmed up again to liquid form while the temperature in the sample is continually measured; thus, the freezing point of the sample can be determined by registration of the temperature change, characterized in that a sample of liquid is collected from the road surface into a container, that the sample of liquid is repeatedly cooled to ice and warmed up again to liquid form, the temperature in the sample being continually measured, that the freezing-point of the sample is determined by registration of the temperature change, and that the container is automatically emptied upon completed determination of the sample's freezing-point.
2. A method according to Claim 1 , characterized in that liquid is prevented from entering the container during registration of the temperature change.
3. A method according to Claim 1 , characterized in that the freezing-point of the sample is determined by registration of the temperature change during at least one cooling phase.
4. A method according to Claim 1 , characterized in that the sample of liquid in the container is heated and cooled, respectively, by a Peltier element.
5. A method according to Claim 1, characterized in that the sample of liquid is collected from the splash from a rotating wheel of a vehicle.
6. A device for measurement of the freezing point, whereby a cooling device (10) and a heating device (11) are provided in a measuring assembly (18) for repeated cooling down and heating, respectively, of a sample of liquid from a road surface to ice and warmed up again to liquid, and measuring means are provided for continual measuring of the temperature of the sample, so that the sample's freezing-point can be determined by registration of the temperature change, characterized in that A container (13) is provided on a vehicle for collection of a sample of liquid from the road surface. that said cooling device (10) and heating device (11) are operatively connected to a control device (14) for repeated cooling of the sample of liquid to ice and warming of the ice to liquid form, and for continual measurement of the sample temperature. that the control device is designed to determine the freezing-point of the sample by registration of the temperature change, and that the container (13) comprises dispensing means (15) to automatically empty the container (13) upon completed determination of the sample's freezing-point.
7. A device according to Claim 6, characterized in that barrier means (2ø)are provided to prevent inflow of liquid during an ongoing process of measurement of the freezing-point.
8. A device according to Claim 7, characterized in that said barrier means (20) is designed as a cover sealing the container (13).
9. A device according to Claim 7, characterized in that said barrier means (20) is designed as a rubber membrane, that the rubber membrane is braced onto a control plate (17) above the container (13), and
that the rubber membrane is extensible by adding a pressure medium such that the container (13) is sealed.
10. A device according to Claim 6, characterized in that a Peltier element (19) constitutes said cooling device (10) and heating device (11).
11. A device according to Claim 6, characterized in that said container (13) is made as a recess in the measuring assembly (18).
12. A device according to Claim 11, characterized in that a cleaning device (15) is provided for cleaning said container (13) between measurements.
13. A device according to Claim 12, characterized in that said cleaning device (15) comprises a compressed air nozzle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU15151/99A AU1515199A (en) | 1997-11-27 | 1998-11-27 | Method and device for determining the freezing point |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9704373-1 | 1997-11-27 | ||
| SE9704373A SE511075C2 (en) | 1997-11-27 | 1997-11-27 | Method and device for freezing point measurement |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1999031492A1 true WO1999031492A1 (en) | 1999-06-24 |
Family
ID=20409152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/SE1998/002144 Ceased WO1999031492A1 (en) | 1997-11-27 | 1998-11-27 | Method and device for determining the freezing point |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU1515199A (en) |
| SE (1) | SE511075C2 (en) |
| WO (1) | WO1999031492A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6695469B2 (en) | 2001-11-19 | 2004-02-24 | Energy Absorption Systems, Inc. | Roadway freezing point monitoring system and method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4383770A (en) * | 1981-07-09 | 1983-05-17 | Boschung Mecatronic Ag | Apparatus for determining the freezing point of a liquid on or from a road surface |
| EP0362173A1 (en) * | 1988-09-29 | 1990-04-04 | Telub Teknik Ab | A method to measure a temperature with a peltier element |
-
1997
- 1997-11-27 SE SE9704373A patent/SE511075C2/en unknown
-
1998
- 1998-11-27 AU AU15151/99A patent/AU1515199A/en not_active Abandoned
- 1998-11-27 WO PCT/SE1998/002144 patent/WO1999031492A1/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4383770A (en) * | 1981-07-09 | 1983-05-17 | Boschung Mecatronic Ag | Apparatus for determining the freezing point of a liquid on or from a road surface |
| EP0362173A1 (en) * | 1988-09-29 | 1990-04-04 | Telub Teknik Ab | A method to measure a temperature with a peltier element |
| US5143451A (en) * | 1988-09-29 | 1992-09-01 | Affarsverket Ffv | Method to measure a temperature with a peltier element |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6695469B2 (en) | 2001-11-19 | 2004-02-24 | Energy Absorption Systems, Inc. | Roadway freezing point monitoring system and method |
| US7090392B2 (en) | 2001-11-19 | 2006-08-15 | Energy Absorption Systems, Inc. | Roadway freezing point monitoring system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| AU1515199A (en) | 1999-07-05 |
| SE511075C2 (en) | 1999-08-02 |
| SE9704373D0 (en) | 1997-11-27 |
| SE9704373L (en) | 1999-05-28 |
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