US20040062289A1 - METHOD FOR DETERMINING THE RELATIVE HUMIDITY OF A VOLUME OF AIR HAVING A TEMPERATURE OF 100º C OR GREATER - Google Patents
METHOD FOR DETERMINING THE RELATIVE HUMIDITY OF A VOLUME OF AIR HAVING A TEMPERATURE OF 100º C OR GREATER Download PDFInfo
- Publication number
- US20040062289A1 US20040062289A1 US10/260,623 US26062302A US2004062289A1 US 20040062289 A1 US20040062289 A1 US 20040062289A1 US 26062302 A US26062302 A US 26062302A US 2004062289 A1 US2004062289 A1 US 2004062289A1
- Authority
- US
- United States
- Prior art keywords
- air
- volume
- temperature
- relative humidity
- determining
- 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.)
- Granted
Links
Images
Classifications
-
- 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
- G01N25/56—Investigating or analyzing materials by the use of thermal means by investigating moisture content
Definitions
- the present invention relates to methods for determining the relative humidity of volumes of air, and in particular to methods for determining the relative humidity of a volume of hot air enclosed within industrial machinery such as veneer dryers and the like.
- Wood is often peeled, sawn, or sliced into sheets of a certain thickness which are combined with adhesive resins to form wood products such as plywood. These wood sheets or “veneer” sheets are formed in veneer mills and are generally dried in veneer dryers before being adhered to one another.
- Plywood veneer dryers are large, heated enclosures through which veneer sheets are transported along a conveyor system.
- a typical veneer dryer might be 80-100 feet in length.
- a typical drying temperature in a veneer dryer might be 200° C.
- air is circulated by large fans to remove moisture from the veneer sheets.
- These veneer dryers dry wet veneer to an average moisture content that is compatible with the adhesive system being used to bond the veneers. This moisture content is also somewhat dependent upon the end product being manufactured.
- Plywood for example, is generally manufactured from veneers having a moisture content of between 3%-8% moisture content by dry weight. The veneers cannot be properly bonded unless they have the correct moisture content.
- Moisture content can generally be controlled by controlling the temperature of the dryer, the length of time the veneers are allowed to be dried, and the relative humidity of the air within the dryers.
- the relative humidity of the air within a veneer dryer is generally controlled by venting hot, humid air from the dryer and replacing it with fresh, cool air.
- venting the hot air from the dryer causes energy losses, and it is desirable to closely monitor the relative humidity so as not to unnecessarily vent an excessive amount of hot air.
- the present invention provides a method for determining the relative humidity of a volume of air having a temperature of 100° C. or greater.
- the method comprises the steps of:
- RH V RH S ⁇ p sat(S) /p sat(V)
- the step of determining the relative humidity RH S of the sample volume of air comprises considering the temperature T S to be the dry bulb temperature of the sample volume of air, and further comprises measuring the wet bulb temperature of the sample volume of air. With these dry and wet bulb temperatures, the relative humidity RH S may be obtained from a reference source.
- the method is carried out within a veneer drying system and the relative humidity of the volume of air calculated is that of the air within the dryer.
- the sample of air removed from the dryer may be returned to the dryer after the calculation of relative humidity is performed.
- FIG. 1 is schematic view of a veneer drying system employing the method of the present invention.
- FIG. 2 is a table showing saturation vapor pressure (e * (T)) for different temperatures (T).
- the inventors foresee the method of the present invention being carried out in many circumstances wherein it is desired to determine the relative humidity of a volume of air having a temperature (or “dry bulb” temperature) of 100° C. or greater.
- the inventors are particularly interested in monitoring relative humidity within veneer dryers, and thus it is such a system which is illustrated and described herein.
- the references herein to veneer dryers are for illustrative purposes only, and that the presently-described system and method will have application in other circumstances and situations.
- the present method provides that the temperature T V of the volume of air 100 within the dryer 10 be measured. This can suitably be accomplished with a temperature sensor such as dry bulb temperature sensor 20 .
- the air 100 within dryer 10 typically has, as described above, a temperature significantly greater than 100° C. “Air” as described herein, refers generally to the various gases within dryer 10 .
- FIG. 2 shows a partial table of saturation vapor pressures for given temperatures.
- a further step in the present method provides, after obtaining temperature T V that the saturation vapor pressure p sat(V) of the air within the dryer 10 be determined from a reference in this fashion, knowing T V .
- the present method also provides the step of collecting a sample volume of air 200 from dryer 10 . This can be accomplished in a dryer system by pumping a relatively small volume of air 200 from dryer 10 by a fan to a collection enclosure 30 remote from dryer 10 .
- the collected sample volume of air 200 is cooled, and may be efficiently cooled by running it through cooling conduit 40 .
- the air 200 is cooled to a temperature T S below 100° C., but air 200 is not allowed to cool to such an extent that condensation occurs. In other words, the air 200 is not cooled to its dew point.
- Temperature T S may be measured by means of dry bulb temperature sensor 50 .
- Other temperature sensors may be placed within conduit 40 to control the amount of cooling of air 200 , so that temperature T S indeed ends up to be below 100° C. once air 200 is within enclosure 30 .
- the saturation vapor pressure p sat(S) of the sample volume of air 200 is determined from T S , as described earlier by referring to well known references.
- the wet bulb temperature of air 200 within enclosure 30 is determined using a wet bulb temperature sensor 60 .
- the wet bulb temperature of air 200 must be determined at the same time T S is determined, or at least, while T S remains constant.
- RH relative humidity of air
- RH relative humidity
- p the partial water vapor pressure in the air
- p sat the saturation water vapor pressure of the air
- RH S relative humidity of sample air 200
- p S is the partial water vapor pressure in the air 200
- p sat(S) is the saturation water vapor pressure of sample air 200 .
- the relative humidity of hot air 100 can be expressed as follows:
- RH V relative humidity of air 100
- p V is the partial water vapor pressure in the air 100
- p sat(V) is the saturation water vapor pressure of the air 100 .
- RH V RH S ⁇ p sat(S) /p sat(V)
- RH V RH S ⁇ p sat(S) /p sat(V)
- steps “f” can precede step “e”. What is essential that the relative humidity of the sample of air, and the saturation pressures of the volume of air and of the sample of air be determined, so that the calculation of step “g” can be performed.
- the hot air dry temperature is measured in a veneer dryer at 135° C.
- a “wet bulb” temperature measurement taken in the dryer would read 45° C., but this is not accurate for the purpose of determining relative humidity due to th high temperature, as discussed above.
- a sample of air is collected from the dryer and cooled to a dry temperature of 75.8° C. When cooled to this temperature, a wet temperature is able to be taken, and it is determined to be 33.1° C. From these dry and wet temperatures, the relative humidity of the cooled sample of air is determined to be 6.81%.
- the saturation water vapor pressure at 75.8° C. is known or determined to be 0.4005 bars.
- the saturation water vapor pressure at 135° C. known to be 3.145 bars, so the relative humidity of the volume of air in the dryer can be calculated to be:
- controller 70 continuously monitors relative humidity of the air within the dryer 10 and makes venting adjustments as required.
Landscapes
- 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)
- Drying Of Solid Materials (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
Description
- The present invention relates to methods for determining the relative humidity of volumes of air, and in particular to methods for determining the relative humidity of a volume of hot air enclosed within industrial machinery such as veneer dryers and the like.
- Wood is often peeled, sawn, or sliced into sheets of a certain thickness which are combined with adhesive resins to form wood products such as plywood. These wood sheets or “veneer” sheets are formed in veneer mills and are generally dried in veneer dryers before being adhered to one another.
- Plywood veneer dryers are large, heated enclosures through which veneer sheets are transported along a conveyor system. A typical veneer dryer might be 80-100 feet in length. A typical drying temperature in a veneer dryer might be 200° C. In these veneer dryers, air is circulated by large fans to remove moisture from the veneer sheets.
- These veneer dryers dry wet veneer to an average moisture content that is compatible with the adhesive system being used to bond the veneers. This moisture content is also somewhat dependent upon the end product being manufactured. Plywood, for example, is generally manufactured from veneers having a moisture content of between 3%-8% moisture content by dry weight. The veneers cannot be properly bonded unless they have the correct moisture content.
- Given the importance of the moisture content of the veneers, then, it is important to monitor and control the moisture content of the veneers in the dryers. Moisture content can generally be controlled by controlling the temperature of the dryer, the length of time the veneers are allowed to be dried, and the relative humidity of the air within the dryers.
- The relative humidity of the air within a veneer dryer is generally controlled by venting hot, humid air from the dryer and replacing it with fresh, cool air. However, venting the hot air from the dryer causes energy losses, and it is desirable to closely monitor the relative humidity so as not to unnecessarily vent an excessive amount of hot air.
- To this point in time there has not been developed a suitable, cost effective system and method for determining and monitoring the relative humidity within a veneer dryer.
- It is quite common and well known to monitor relative humidity within a lumber kiln using the dry and wet bulb method, which will be very familiar to those with knowledge of wood drying and with psychrometry generally. The relative humidity within a lumber kiln can be determined by obtaining the dry bulb temperature and the wet bulb temperature within the kiln and by thereafter referring to a reference table or a database for the relative humidity given these two temperatures. However, it is well known that the dry and wet bulb method of determining relative humidity cannot be suitably relied upon to provide accurate determinations of relative humidity when the temperature of the air exceeds 100° C. (the boiling point of water), as it does in a veneer dryer, since proper wet bulb temperatures cannot be obtained.
- Accordingly, relative humidity has not typically been determined in veneer dryers by the dry and wet bulb method. Rather, various expensive and complicated optical and electrical systems have been suggested and employed. Other systems (such as the “Zirconia Oxygen Analyzer”) measure oxygen content directly and humidity indirectly, but these systems do not provide accurate readings in atmospheric environments like those within a veneer dryer wherein the “fresh” air has been contaminated by organic compounds given off by the drying wood, and by byproducts of the combustion of fuels (such as natural gas) used to heat the air within the veneer dryer. So, these oxygen-measuring systems, as expensive as they might be, do not provide very accurate readings within a veneer dryer.
- There accordingly remains a need for a relatively simple, inexpensive method for determining the relative humidity of a volume of hot air enclosed within a veneer dryer.
- The present invention provides a method for determining the relative humidity of a volume of air having a temperature of 100° C. or greater. The method comprises the steps of:
- measuring the temperature TV of the volume of air;
- determining from TV the saturation vapor pressure psat(V) of the volume of air;
- collecting from the volume of air a sample volume of air;
- cooling the sample volume of air to a temperature TS below 100° C., but above the dew point of the sample volume of air;
- determining from TS the saturation vapor pressure psat(S) of the cooled sample volume of air;
- determining the relative humidity RHS of the sample volume of air; and
- performing the calculation
- RH V =RH S ×p sat(S) /p sat(V)
- to obtain a relative humidity RHV of the volume of air.
- In a preferred embodiment, the step of determining the relative humidity RHS of the sample volume of air comprises considering the temperature TS to be the dry bulb temperature of the sample volume of air, and further comprises measuring the wet bulb temperature of the sample volume of air. With these dry and wet bulb temperatures, the relative humidity RHS may be obtained from a reference source.
- In a further preferred embodiment of the invention, the method is carried out within a veneer drying system and the relative humidity of the volume of air calculated is that of the air within the dryer. The sample of air removed from the dryer may be returned to the dryer after the calculation of relative humidity is performed.
- In the accompanying drawings which illustrate specific embodiments of the invention, but which should not be construed as restricting the spirit or scope of the invention in any way:
- FIG. 1 is schematic view of a veneer drying system employing the method of the present invention.
- FIG. 2 is a table showing saturation vapor pressure (e*(T)) for different temperatures (T).
- Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practised without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
- The inventors foresee the method of the present invention being carried out in many circumstances wherein it is desired to determine the relative humidity of a volume of air having a temperature (or “dry bulb” temperature) of 100° C. or greater. The inventors are particularly interested in monitoring relative humidity within veneer dryers, and thus it is such a system which is illustrated and described herein. However, it should be understood that the references herein to veneer dryers are for illustrative purposes only, and that the presently-described system and method will have application in other circumstances and situations.
- Accordingly, referring to FIG. 1, in a system wherein it is desired to determine the relative humidity of a volume of hot air, such as within an enclosure like a veneer dryer10, the present method provides that the temperature TV of the volume of
air 100 within the dryer 10 be measured. This can suitably be accomplished with a temperature sensor such as drybulb temperature sensor 20. Theair 100 within dryer 10 typically has, as described above, a temperature significantly greater than 100° C. “Air” as described herein, refers generally to the various gases within dryer 10. - As is well known to those in the art of psychrometry, air at a given temperature has a fixed saturation vapor pressure. As known in the art, this pressure can be determined from any number of reference sources, such as the following, all of which are incorporated herein by reference:
- List, Robert J. Smithsonian Meteorological Tables. Smithsonian Institution Press, City of Washington
- Allen, Richard G. et al. 1998. Crop evapotranspiration—Guidelines for computing crop water requirements—FAO Irrigation and drainage paper 56. Food and Agriculture Organization of the United Nations
- Harrison, L. D. 1965. Fundamental concepts and definitions relating to humidity. Humidity and Moisture (A. Wexler, ed), Meas. Contr. Sci. Ind. 3:3-70
- Jensen, M. E., R. D. Burman, and R. G. Allen. 1990. Evapotranspiration and irrigation water requirements. ASCE Manuals and Reports on Engineering Practice No. 70.
- Murray, F. W. 1967. On the computation of saturation vapor pressure. J. App. Meteor. 6:203-204.
- Rosenberg, N. J., B. L. Blad, and S. B. Verma. 1990. Microclimate. Second edition. John Wiley & Sons, New York
- FIG. 2 shows a partial table of saturation vapor pressures for given temperatures.
- A further step in the present method provides, after obtaining temperature TV that the saturation vapor pressure psat(V) of the air within the dryer 10 be determined from a reference in this fashion, knowing TV.
- The present method also provides the step of collecting a sample volume of
air 200 from dryer 10. This can be accomplished in a dryer system by pumping a relatively small volume ofair 200 from dryer 10 by a fan to acollection enclosure 30 remote from dryer 10. The collected sample volume ofair 200 is cooled, and may be efficiently cooled by running it through coolingconduit 40. - The
air 200 is cooled to a temperature TS below 100° C., butair 200 is not allowed to cool to such an extent that condensation occurs. In other words, theair 200 is not cooled to its dew point. Temperature TS may be measured by means of drybulb temperature sensor 50. Other temperature sensors (not shown) may be placed withinconduit 40 to control the amount of cooling ofair 200, so that temperature TS indeed ends up to be below 100° C. onceair 200 is withinenclosure 30. - In a subsequent step of the present method, the saturation vapor pressure psat(S) of the sample volume of
air 200 is determined from TS, as described earlier by referring to well known references. Before or after this particular step, but afterair 200 has been cooled, the wet bulb temperature ofair 200 withinenclosure 30 is determined using a wetbulb temperature sensor 60. Of course, the wet bulb temperature ofair 200 must be determined at the same time TS is determined, or at least, while TS remains constant. - As is well known in the art, at any particular temperature, the relative humidity of air (RH) can be determined by the following calculation:
- RH=p/p sat
- where RH is relative humidity, p is the partial water vapor pressure in the air, and psat is the saturation water vapor pressure of the air.
- Given this relationship, the relative humidity of cooled
air 200 can be expressed as follows: - RH S =p S /p sat(S)
- where RHS is relative humidity of
sample air 200, pS is the partial water vapor pressure in theair 200, and psat(S) is the saturation water vapor pressure ofsample air 200. - Further, the relative humidity of
hot air 100 can be expressed as follows: - RH V =p V /p sat(V)
- where RHV is relative humidity of
air 100, pV is the partial water vapor pressure in theair 100, and psat(V) is the saturation water vapor pressure of theair 100. - The ratio of RHS/RHV can be expressed as follows:
- pS×psat(V)/pV×psat(S)
- Since the absolute humidity does not change before or after cooling, if condensation is not permitted to occur, pS=pV, and
- RH S /RH V =p sat(V) /p sat(S)
- Thus, RH V =RH S ×p sat(S) /p sat(V)
- Accordingly, knowing RHS, psat(S) and psat(V), the relative humidity RHV within a veneer dryer can be calculated.
- The various steps in the method might be summarized as follows, then:
- a) measuring the temperature TV of a volume of air;
- b) determining from the temperature TV the saturation vapor pressure psat(V) of the volume of air;
- c) collecting from the volume of air a sample volume S of air;
- d) cooling the sample volume of air to a temperature TS below 100° C., but above the dew point of the sample volume of air;
- e) determining from the temperature TS the saturation vapor pressure psat(S) of the cooled sample volume of air;
- f) determining the relative humidity RHS of the sample volume of air by measuring the wet bulb temperature of the sample volume of air and determining the relative humidity from the temperature TS and from the wet bulb temperature; and
- g) performing the calculation
- RH V =RH S ×p sat(S) /p sat(V)
- to obtain a relative humidity RHV of said volume of air.
- It should be clear that while certain of these steps must follow others, some can be performed in an order other than indicated above. For example, it will be understood that steps “f” can precede step “e”. What is essential that the relative humidity of the sample of air, and the saturation pressures of the volume of air and of the sample of air be determined, so that the calculation of step “g” can be performed.
- The hot air dry temperature is measured in a veneer dryer at 135° C. A “wet bulb” temperature measurement taken in the dryer would read 45° C., but this is not accurate for the purpose of determining relative humidity due to th high temperature, as discussed above. A sample of air is collected from the dryer and cooled to a dry temperature of 75.8° C. When cooled to this temperature, a wet temperature is able to be taken, and it is determined to be 33.1° C. From these dry and wet temperatures, the relative humidity of the cooled sample of air is determined to be 6.81%. The saturation water vapor pressure at 75.8° C. is known or determined to be 0.4005 bars. The saturation water vapor pressure at 135° C. known to be 3.145 bars, so the relative humidity of the volume of air in the dryer can be calculated to be:
- RH V=6.81%×0.4005/3.145=0.868%
- The inventors foresee the use of the method in a continuously-operating feedback system such as that shown in FIG. 1, wherein the
air 200 is continuously collected from dryer 10, and sampled.Air 200 may be returned to dryer 10 by conduit 80 (rather than merely vented to the atmosphere). In this system,controller 70 continuously monitors relative humidity of the air within the dryer 10 and makes venting adjustments as required. - As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
Claims (5)
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/260,623 US6712504B1 (en) | 2002-10-01 | 2002-10-01 | Method for determining the relative humidity of a volume of air having a temperature of 100° C or greater |
CA002443197A CA2443197C (en) | 2002-10-01 | 2003-09-29 | Method to measure relative humidity of a volume of air having a temperature of 100.degree.c or greater |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/260,623 US6712504B1 (en) | 2002-10-01 | 2002-10-01 | Method for determining the relative humidity of a volume of air having a temperature of 100° C or greater |
Publications (2)
Publication Number | Publication Date |
---|---|
US6712504B1 US6712504B1 (en) | 2004-03-30 |
US20040062289A1 true US20040062289A1 (en) | 2004-04-01 |
Family
ID=31993530
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/260,623 Expired - Fee Related US6712504B1 (en) | 2002-10-01 | 2002-10-01 | Method for determining the relative humidity of a volume of air having a temperature of 100° C or greater |
Country Status (2)
Country | Link |
---|---|
US (1) | US6712504B1 (en) |
CA (1) | CA2443197C (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2469174A3 (en) * | 2010-12-22 | 2014-07-02 | Miele & Cie. KG | Cooking device |
CN105784926A (en) * | 2014-12-26 | 2016-07-20 | 国核华清(北京)核电技术研发中心有限公司 | Device and method used for measuring moisture content of high humidity gas flow |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102008024021B4 (en) * | 2008-05-16 | 2010-02-11 | Rational Ag | Method for moisture measurement, condensing pressure chamber for this purpose and cooking appliance hereby |
CN101858876B (en) * | 2010-06-01 | 2012-03-21 | 东莞市升微机电设备科技有限公司 | Detecting system and humidity detecting method for detecting volatile organic compound |
JP5969596B2 (en) * | 2012-04-16 | 2016-08-17 | エスペック株式会社 | Hygrometer and temperature and humidity chamber equipped with this hygrometer |
US10067002B2 (en) * | 2016-06-08 | 2018-09-04 | Mark Smith | Retrofit gas kiln atmospheric monitoring system |
US9848629B1 (en) * | 2016-12-21 | 2017-12-26 | Wenger Manufacturing, Inc. | Product drying apparatus and methods |
Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3681992A (en) * | 1969-11-21 | 1972-08-08 | Gen Time Corp | Weather instrument for indicating comfort temperature and relative humidity values |
US3890703A (en) * | 1974-02-19 | 1975-06-24 | Plessey Inc | Method of making humidity sensor |
US3926052A (en) * | 1974-05-06 | 1975-12-16 | Johnson Service Co | Relative humidity computer |
US4227411A (en) * | 1979-09-24 | 1980-10-14 | Rca Corporation | Relative humidity measurement |
US4408482A (en) * | 1981-12-18 | 1983-10-11 | Tsentralny Nauchno-Issledovatelsky Institut Kozhevenno-Obuvnoi Promyshlennosti | Method and apparatus for the determination of moisture content of fibrous and granular materials |
USH381H (en) * | 1986-12-16 | 1987-12-01 | The United States Of America As Represented By The Secretary Of The Army | Condition monitoring device |
US5148710A (en) * | 1990-02-23 | 1992-09-22 | Gudehus Hans C | Method and apparatus for determining the relative humidity of gaseous materials |
US5165793A (en) * | 1991-10-11 | 1992-11-24 | Lustron Corporation | Dew point measuring method and apparatus |
US5168754A (en) * | 1992-01-02 | 1992-12-08 | Carrier Corporation | Method and apparatus for detecting room humidity |
US5435146A (en) * | 1994-09-23 | 1995-07-25 | Carrier Corporation | Method and apparatus for determining relative humidity |
US5485747A (en) * | 1993-08-23 | 1996-01-23 | Vaisala Oy | Method of measurement of relative humidity, in particular in radiosondes, and humidity detectors that make use of the method |
US5816704A (en) * | 1996-06-04 | 1998-10-06 | Decagon Devices, Inc. | Water activity and dew point temperature measuring apparatus and method |
US6073480A (en) * | 1996-12-13 | 2000-06-13 | Panametrics, Inc. | Humidity sensor with differential thermal detection and method of sensing |
US6229318B1 (en) * | 1997-02-25 | 2001-05-08 | Toshikazu Suda | Electrical resistance type humidity sensor |
US6299147B1 (en) * | 1998-09-25 | 2001-10-09 | E&E Elektronik Ges M.B.H. | Device for generating a defined relative humidity |
-
2002
- 2002-10-01 US US10/260,623 patent/US6712504B1/en not_active Expired - Fee Related
-
2003
- 2003-09-29 CA CA002443197A patent/CA2443197C/en not_active Expired - Fee Related
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3681992A (en) * | 1969-11-21 | 1972-08-08 | Gen Time Corp | Weather instrument for indicating comfort temperature and relative humidity values |
US3890703A (en) * | 1974-02-19 | 1975-06-24 | Plessey Inc | Method of making humidity sensor |
US3926052A (en) * | 1974-05-06 | 1975-12-16 | Johnson Service Co | Relative humidity computer |
US4227411A (en) * | 1979-09-24 | 1980-10-14 | Rca Corporation | Relative humidity measurement |
US4408482A (en) * | 1981-12-18 | 1983-10-11 | Tsentralny Nauchno-Issledovatelsky Institut Kozhevenno-Obuvnoi Promyshlennosti | Method and apparatus for the determination of moisture content of fibrous and granular materials |
USH381H (en) * | 1986-12-16 | 1987-12-01 | The United States Of America As Represented By The Secretary Of The Army | Condition monitoring device |
US5148710A (en) * | 1990-02-23 | 1992-09-22 | Gudehus Hans C | Method and apparatus for determining the relative humidity of gaseous materials |
US5165793A (en) * | 1991-10-11 | 1992-11-24 | Lustron Corporation | Dew point measuring method and apparatus |
US5168754A (en) * | 1992-01-02 | 1992-12-08 | Carrier Corporation | Method and apparatus for detecting room humidity |
US5485747A (en) * | 1993-08-23 | 1996-01-23 | Vaisala Oy | Method of measurement of relative humidity, in particular in radiosondes, and humidity detectors that make use of the method |
US5435146A (en) * | 1994-09-23 | 1995-07-25 | Carrier Corporation | Method and apparatus for determining relative humidity |
US5816704A (en) * | 1996-06-04 | 1998-10-06 | Decagon Devices, Inc. | Water activity and dew point temperature measuring apparatus and method |
US6073480A (en) * | 1996-12-13 | 2000-06-13 | Panametrics, Inc. | Humidity sensor with differential thermal detection and method of sensing |
US6229318B1 (en) * | 1997-02-25 | 2001-05-08 | Toshikazu Suda | Electrical resistance type humidity sensor |
US6299147B1 (en) * | 1998-09-25 | 2001-10-09 | E&E Elektronik Ges M.B.H. | Device for generating a defined relative humidity |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2469174A3 (en) * | 2010-12-22 | 2014-07-02 | Miele & Cie. KG | Cooking device |
CN105784926A (en) * | 2014-12-26 | 2016-07-20 | 国核华清(北京)核电技术研发中心有限公司 | Device and method used for measuring moisture content of high humidity gas flow |
Also Published As
Publication number | Publication date |
---|---|
CA2443197A1 (en) | 2004-04-01 |
CA2443197C (en) | 2007-03-13 |
US6712504B1 (en) | 2004-03-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN108802352B (en) | Method for measuring water content in wood drying process and wood drying method | |
US6712504B1 (en) | Method for determining the relative humidity of a volume of air having a temperature of 100° C or greater | |
ATE505699T1 (en) | DRYING SCALE | |
US5915811A (en) | Solar drying process and apparatus | |
Herritsch et al. | Intermittent and continuous drying of red beech timber from the green condition | |
US20030034443A1 (en) | Absolute humidity sensor to control drying equipment | |
FI89309B (en) | METHOD FOER ATT BESTAEMMA FUKTINNEHAOLLET HOS PRODUKTER TILLVERKADE AV CELLULOSAMATERIAL | |
Caps et al. | Quality control of vacuum insulation panels: Methods of measuring gas pressure | |
Gaffney et al. | High-temperature forced-air research facility for heating fruits for insect quarantine treatments | |
Seyfarth et al. | Continuous drying of lumber in a microwave vacuum kiln | |
Perré et al. | Energy consumption in the convective drying of timber analyzed by a multiscale computational model | |
Sawhney et al. | Determination of drying constants and their dependence on drying air parameters for thin layer onion drying | |
Roberts | Dew point temperature | |
Kang et al. | A radial distribution of moistures and tangential strains within a larch log cross section during radio-frequency/vacuum drying | |
CN112130601B (en) | Humidity control method and device for test chamber, electronic equipment and storage medium | |
Ananias et al. | Introducing an overall mass-transfer coefficient for prediction of drying curves at low-temperature drying rates | |
Lee et al. | Comparison of shrinkage, checking, and absorbed energy in impact bending of Korean ash squares dried by a radio-frequency/vacuum process and a conventional kiln | |
Liu et al. | Effect of temperature, relative humidity and ach on the emission of volatile organic compounds from particleboard | |
GB2184037A (en) | Measuring the rate of formaldehyde emission from resin-bonded and resin-impregnated materials | |
Vermaas et al. | Low temperature drying of Eucalyptus grandis. A preliminary laboratory evaluation | |
Teischinger et al. | Sawn Timber Steaming and Drying | |
Kumar et al. | Vacuum press drying studies on two fast-growing Indian wood species | |
Bengtsson et al. | Measurement and mathematical modeling of the hydrocarbon emissions from wood drying | |
Cai et al. | Impact of mountain pine beetle (MPB) attack on drying characteristics of wood | |
RU2281460C1 (en) | X-ray device for inspecting thickness of rolled products |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: FORINTEK CANADA CORP., BRITISH COLUMBIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:DAI, CHUNPING;DU, GUOXING;REEL/FRAME:013348/0246 Effective date: 20020926 |
|
FEPP | Fee payment procedure |
Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY |
|
AS | Assignment |
Owner name: FPINNOVATIONS, QUEBEC Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:FORINTEK CANADA CORPORATION;REEL/FRAME:019181/0705 Effective date: 20070326 |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20160330 |