阅读说明：本技术 表征、区分和测量接触区域的方法 (Method for characterizing, differentiating and measuring contact areas ) 是由 D·休姆 D·兰德里 A·伊万斯 于 2021-06-16 设计创作，主要内容包括：本发明涉及确定接触区域的热特性的方法。该方法包括接收传感器的温度数据；确定从传感器到至少一种材料的热穿透的温度分布；对温度分布应用校正；迭代分析所校正的温度分布；以及输出接触区域的热属性,该接触区域是传感器与至少一种材料之间的区域。该方法可进一步包括确定至少一种材料的热属性；以及利用接触区域的热属性确定材料的校正热属性。该方法可进一步包括自动确定适当的时间窗口,用于测量至少一种材料的特性,以使接触区域的影响最小化。(The invention relates to a method of determining thermal properties of a contact region. The method includes receiving temperature data of a sensor; determining a temperature profile of heat penetration from the sensor to the at least one material; applying a correction to the temperature profile; iteratively analyzing the corrected temperature distribution; and outputting the thermal property of a contact region, the contact region being a region between the sensor and the at least one material. The method may further include determining a thermal property of at least one material; and determining a corrected thermal property of the material using the thermal property of the contact region. The method may further comprise automatically determining an appropriate time window for measuring the property of the at least one material to minimize the effect of the contact area.)

1. A method, comprising:

receiving temperature data of a sensor;

determining a temperature profile of heat penetration from the sensor to the at least one material;

applying a correction to the temperature profile;

iteratively analyzing the corrected temperature distribution; and

outputting a thermal characteristic of a contact area, the contact area being an area between the sensor and the at least one material.

2. The method of claim 1, wherein the temperature data is a temperature of the sensor over time, wherein the iterative analysis is a non-linear fit analysis.

3. The method of claim 1, wherein the contact region comprises the sensor and is between two of the at least one material.

4. The method of any of claims 1 to 3, further comprising:

determining a thermal property of the at least one material; and

determining a corrected thermal property of the at least one material using the thermal property of the contact region.

5. The method of any of claims 1 to 3, further comprising: automatically determining an appropriate time window for measuring a property of the at least one material to minimize an effect of the contact area.

6. The method of claim 1 or 2, wherein there is a thin film between the sensor and the at least one material, and the method further comprises determining a thermal property of the thin film.

7. A method, comprising:

arranging a sensor in a contact area between a first material and a second material;

heating the sensor for a predetermined time;

determining a temperature profile of heat penetration of the sensor to the first material or the second material;

applying a correction to the temperature profile; and

determining a thermal characteristic of the contact region, the contact region being a region between the first material and the second material.

8. The method of claim 7, further comprising iteratively analyzing the temperature distribution to determine the thermal characteristic of the contact region.

9. The method of claim 7 or 8, further comprising:

determining thermal properties of the first material and the second material; and

determining corrected thermal properties of the first material and the second material using the thermal properties of the contact region.

10. The method of claim 7 or 8, further comprising: automatically determining an appropriate time window for measuring the properties of the first and second materials to minimize the effect of the contact area.

Technical Field

The present disclosure relates to thermal property measurement, and in particular to thermal property measurement of contact areas between materials in contact.

Background

Thermal property analysis may be performed on the materials in contact, such as flow rate (efficiency) of surface and bulk materials (bulk materials). When thermal property analysis is performed on materials in contact, physical contact between the materials is not considered. It is common to measure a combination of bulk material properties and surface properties without distinguishing bulk material properties from surface or contact properties. It is understood that physical contact between two or more materials in contact can have an effect on the thermal property analysis of the materials. For example, the porosity, heterogeneity, and/or surface defects of one or more materials may significantly alter the thermal properties of the material.

Accordingly, methods for characterizing, distinguishing, and measuring thermal properties of contact between materials are desirable.

Disclosure of Invention

According to one aspect of the disclosure, a method is disclosed, the method comprising: receiving temperature data of a sensor; determining a temperature profile of heat penetration from the sensor to the at least one material; applying a correction to the temperature profile; iteratively analyzing the corrected temperature distribution; and outputting a thermal property of a contact region, the contact region being a region between the sensor and the at least one material.

In the method, the temperature data may be a temperature of the sensor over time.

In the method, the contact region may include a sensor and may be between two materials of the at least one material.

In this method, the iterative analysis may be a non-linear fit analysis.

The method may further include determining a thermal property of at least one material; and determining a corrected thermal property of the at least one material using the thermal property of the contact region.

The method may further comprise automatically determining an appropriate time window for measuring the property of the at least one material to minimize the effect of the contact area.

In the method, there may be a thin film between the sensor and the at least one material. The method may further include determining a thermal property of the film.

In accordance with another aspect of the disclosure, a method is disclosed that includes receiving temperature data of a sensor; determining a temperature profile of heat penetration from the sensor to the two or more materials; applying a correction to the temperature profile; determining a thermal characteristic of a contact region, the contact region being a region between each of the two or more materials; and outputting the thermal characteristic of the contact region.

In the method, the temperature data may be a temperature of the sensor over time.

In this method, the sensor may be in the contact region.

The method may further include iteratively analyzing the corrected temperature distribution prior to determining the thermal characteristic of the contact region. The iterative analysis is a non-linear fit analysis.

The method may further comprise determining thermal properties of the two or more materials; and determining a corrected thermal property of the two or more materials using the thermal property of the contact region.

The method may further comprise automatically determining an appropriate time window for measuring the properties of the two or more materials to minimize the effect of the contact area.

In the method, there may be at least one thin film between the sensor and at least one of the two or more materials. The method may further include determining a thermal property of the at least one film.

According to another aspect of the present disclosure, there is provided a method comprising: arranging a sensor in a contact area between a first material and a second material; heating the sensor for a predetermined time; determining a temperature profile of heat penetration of the sensor to the first material or the second material; iteratively analyzing the temperature distribution; and determining a thermal property of a contact region, the contact region being a region between the first material and the second material.

The method may further comprise applying a correction to the temperature distribution before iteratively analyzing the temperature distribution.

The method may further include determining thermal properties of the first material and the second material; and determining corrected thermal properties of the first material and the second material using the thermal properties of the contact region.

The method may further comprise automatically determining an appropriate time window for measuring the properties of the first material and the second material to minimize the effect of the contact area.

In the method, there may be at least one thin film between the sensor and at least one of the first material and the second material. The method may further include determining a thermal property of the at least one film.

Drawings

Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

Fig. 1 depicts a thermal contact model.

Fig. 2 depicts an embodiment of a thermal contact model using a thin film.

FIG. 3 depicts an embodiment of a thermal contact model using a layered system.

Fig. 4 depicts an embodiment of an asymmetric thermal contact model.

Fig. 5 depicts a graph showing temperature measurements using a thermal contact model of extruded polystyrene.

Fig. 6 depicts a graph showing temperature measurements of a thermal contact model using a coarse EPS.

Fig. 7 depicts a graph showing temperature measurements using a thermal contact model of cut EPS.

FIG. 8 depicts a graph showing temperature measurements over 0 to 10 seconds using a thermal contact model of stainless steel 304; and

fig. 9 depicts a graph showing temperature measurements over 0 to 0.5 seconds using a thermal contact model of polished stainless steel 304.

It is noted that like features are identified by like reference numerals throughout the drawings.

Detailed Description

Methods and models for determining thermal characteristics of a contact region are disclosed herein. The method includes receiving temperature data of a sensor and determining a temperature profile of heat penetration from the sensor to at least one material. The correction term is then applied to the temperature distribution to determine a corrected temperature distribution. Iteratively analyzing the corrected temperature distribution and outputting a thermal characteristic of the at least one contact region. The contact region may be a region between two materials. The contact area includes an area between the sensor and the at least one material.

The method of determining the thermal properties of the contact area between two materials may be applied using a thermal contact model. This method can also be considered as a method of determining the contact characteristics between the planes of materials. The thermal contact model will be further explained below.

As described above, when materials in contact are analyzed for their thermal properties, physical contact between the materials is not taken into account. It will be appreciated that physical contact between two or more materials in contact can have an effect on the thermal properties of the material being analyzed, particularly the porosity, heterogeneity and/or surface defects of one or more of the materials. The methods and models described herein can be used for experimental measurements of different materials and surfaces. Both surface or contact thermal properties (e.g., heat flow rate) and bulk material thermal properties can be extracted from planar source measurements of thermal properties.

To calculate and measure the thermal properties of materials or bodies in contact, the thermal contact and surface flow rate between materials can be characterized, differentiated and measured using the methods and models described herein, which can be derived from thermal waves. It will be appreciated that heat reflection may provide a useful method to model the transfer of heat between material interfaces. When thermal waves encounter an interface between two materials, they are reflected and transmitted. The coefficients and properties of reflection and transmission of thermal waves (amplitude is temperature) from a first material into a second material can be used to determine the time evolution of any temperature distribution, for example, by means of an image. This is at least partly because it is possible to decompose the temperature distribution into a set of thermal waves and the coefficients of reflection and transmission are frequency independent for thermal waves at the interface of two materials.

Fig. 1 depicts a thermal contact model 100. The thermal contact model is a one-dimensional model that can be used to characterize the effects of imperfect contact between materials, such as for transient planar source methods. The thermal contact model 100 includes a first material 102 and a second material 104. The materials 102, 104 may both be the same bulk sample material, with heat flow rate b₂And a diffusion rate alpha₂. It is understood that materials 102 and 104 may each be a different material, having different heat flow rates and diffusivity, as described further below. Sensor 106 is placed on the material102. 104 in the contact region 108 between them. The sensor 106 may be a planar sensor that is embedded or sandwiched in the center of a contact region 108 between the two materials 102, 104. The sensor 106 may be a heat source that heats at a constant power for a predetermined amount of time.

The contact region 108 may be 2L wide and b heat flow rate₁A thin region of (a). The contact region 108 may be considered a thin barrier separating the materials 102, 104, representing the surfaces where the materials 102, 104 are in contact. It will be appreciated that this approximation may allow the contact area 108 between the sensor 106 and the materials 102, 104 to be treated as a single uniform layer.

Although the contact region 108 in the model 100 is represented as a single homogenous layer, it may be more accurately described as a series of layers having different thermal properties. It will be appreciated that a single layer approximation will hold true if the layers are thin enough and are heated for a long enough time. The multilayer interface may produce frequency dependent reflections due to interference, which however has little effect on the low frequency content of the heating process, which dominates the heat transfer for a short time for a constant power source.

For calculations and measurements using the thermal contact model 100, the sensor 106 or heating element is located at x-0, creating a symmetric case. When | x | > L, the materials 102, 104 are introduced in the x-direction.

The thermal contact model 100 may be used to measure and calculate various thermal properties of the contact region 108 and materials 102, 104, as described above and further below. It will be appreciated that imaging methods with reflection coefficients may be used to calculate or determine the temperature distribution of the model 100. In some embodiments, the width 2L of the contact region 108 is unknown. Without a direct measure of L, the diffusivity of the contact region 108 is not readily available. Instead, the temperature equation for the sensor 106 may be defined in terms of a time constant. The time constant may be selected, for example, asUsing such a time constant, the temperature of the sensor 106 can be expressed as equation 1:

where P is the power supplied to the system, t is the time, b₁And b₂The heat flow rates of the contact region 108 and the materials 102, 104, respectively, and t_LIs a time constant. The time constant may be used to identify the earliest time that the thermal contact model 100 or existing thermal characteristic determination methods may be considered valid.

The present invention can utilize the time constant to automatically determine the time window in which the data from the previous method should be considered. This time window represents when the touch offset will be constant. The data in this time window is considered valid data for determining thermal characteristics in existing characteristic determination methods. Valid data may be considered as data where contact between materials has minimal impact on the thermal properties of the materials.

Time constant t_LIt can also be used to derive the thermal contact conductivity H and the heat capacity ξ per unit area of the contact region 108 between one side of the sensor 106 and the material 104. The thermal contact conductivity H is the inverse of the thermal contact resistivity.

It will be appreciated that although the derivation described above relies on a one-dimensional model 100, the derivation can also be used to obtain an approximate correction term for higher dimensional models, such as planar disk sources, in a sufficiently short test time. The correction term represents the effect of contact between the materials and the effect of the sensor itself. If at time (t) is greater than the time constant (t)_L) (i.e., t > t_L) Before the heat transfer remains approximately one-dimensional, then the contact correction will reach a constant offset before the high-dimensional effects become relevant, since the temperature of the sensor can be found as follows:

it will be further appreciated that if the heat transfer in the contact model 100 is at t > t_LStill primarily one-dimensional before, then the contact correction termCan be applied directly to a three-dimensional model of a planar source and is written as equation 3:

where P is the power supplied to the system, t is the time, b1 and b₂The heat flow rates, t, of the contact region 108 and the materials 102, 104, respectively_LIs a time constant.

Correction term (T)_C(T)) can be applied to a transient planar source model (three-dimensional model) with a temperature rise of T_mdl(t) of (d). The corrected form of the model can be found using equation 4:

T_3D(t)＝T_mdl(t)+T_C(t) (4)

for disk heat source and isotropic samples, T_mdl(t) can be written as equation 5:

wherein λ₂Is the thermal conductivity of the sample material, I₀Is a first modified Bessel (Bessel) function.

The thermal contact model 100 described above may be used to determine thermal characteristics of the contact region 108 or the surface of the materials 102, 104. This can be done by iteratively analyzing equation 4 above. The iterative analysis may be a non-linear fit analysis. Iterative analysis may be used to isolate the thermal characteristics of the contact region 108. To accurately and efficiently perform the iterative analysis, a computer is used. The computer automatically, efficiently and accurately performs iterative analysis on the data. It will be appreciated that non-linear fit analysis is also performed on the one-dimensional model of the equation.

By determining the thermal characteristics of the contact region 108, the thermal characteristics of the materials 102, 104 may be more accurately determined. This can be done because in previous methods, as described above, the effect of the contact area or surface of the material was not considered when simulating a transient planar source. The method takes into account the effects of contact between materials using the correction terms of the model 100. The determined thermal characteristics of the contact region may include, but are not limited to, thermal conductivity, inverse thermal resistivity of the contact region, and heat capacity per unit area.

Fig. 2 depicts an embodiment of a thermal contact model 200 using a thin film 210. Thermal contact model 200 is similar to thermal contact model 100. The thermal contact model 200 includes a first material 202 and a second material 204. The materials 202, 204 may be of a heat flow rate b₂And a diffusion rate alpha₂The same bulk sample material. It is understood that materials 202 and 204 may be different materials having different heat flow rates and diffusivities, respectively. The sensor 206 is placed between the materials 202, 204. Contact model 200 further includes a film 210 disposed between material 202 and sensor 206 and between material 204 and sensor 206. There is a contact area 208 between the two films 210 and a contact area 212 between the materials 202, 204 and the films 210. It can be said that the membrane 210 has good contact with the sensor 206. However, it is understood that in other embodiments, contact between the film 210 and the sensor 206 may not be considered good contact. The contact region 208 and the contact region 212 may have different characteristics or may have the same characteristics.

The sensor 206 may be a planar sensor that is embedded or sandwiched in the center between the film 210 and the two materials 202, 204. The sensor 206 may be a heat source that heats at a constant power for a predetermined time. Similar to thermal contact model 100, contact areas 208 and 212 may be thin areas and have a different heat flow rate than materials 202, 204 and thin film 210.

When film 210 is said to have good contact with sensor 206, the thermal properties of film 210 can be found in a manner similar to model 100 described above. The thermal properties of the film 210 can be found in the manner of the contact model 100, however, the reflection coefficient (R) is replaced by the appropriate effective R and then inserted into at least equation 5. The difference between the width of film 210 at contact area 212 of distance sensor 206 and the width of film 210 at contact area 208 of distance sensor 206 (which is the approximate width of film 210) should be known to calculate the thermal properties of film 210. It will be appreciated that without a method of directly measuring the width of film 210, the time constants used in the above method and model may be selected.

The contact model 200 may also be used to measure characteristics of the contact region 212. It will be appreciated that if the film 210 is instead a sample material having similar dimensions to the materials 202, 204 and having known properties, then the characteristics of the contact region 208 can be calculated using a shorter test time. This shorter test time may allow heat from the sensor 206 to not interact with the contact region 212 and the materials 202, 204. Longer test times may then be used to calculate the characteristics of the contact region 212. Such a method can calculate the contact characteristics between any two sample materials, not just the contact characteristics between the sensor and the sample material.

As described above, the thermal contact model 200 may be used to measure and calculate various thermal properties of the materials 202, 204, the thin film 210, the contact region 208, and the contact region 212. For calculations and measurements using the thermal contact model 200, the sensor 206 or heating element is located at x-0, creating a symmetrical situation similar to the contact model 100. In the above equation, the heat flow rate of the film 210 can be represented as b₁This is the heat flow rate of the contact region 108 described above.

Fig. 3 depicts an embodiment of an asymmetric thermal contact model 300. In the thermal contact model 300, there is a first material 302 and a second material 304, which are in contact with a sensor 306, respectively. Material 302 may be a different material than material 304, with a different heat flow rate. The sensor 306 may be a planar sensor that is embedded or sandwiched in a contact region 308 between the first and second materials 302, 304. The sensor 306 may be a heat source that heats at a constant power for a predetermined time. The contact region 308 may have a total width d (w)₁+w₂D) heat flow rate b₁Is thin and thinRegion where the width from sensor 306 to material 302 is w₁The width from sensor 306 to material 304 is w₂。

The contact area 308 consists of two physical contact areas of the sensor 306 and the materials 302, 304. The heat source or sensor 306 need not be placed in the middle of the contact region 308 as shown in fig. 3. It is to be understood that although the sensor 306 is not necessarily centered between the first and second materials 302, 304, the sensor 306 is considered to be at x-0 when the model is applied. Similar to the models 100, 200 described above, the contact region 308 may be considered a thin barrier separating the materials 302, 304, representing the surfaces where the materials 302, 304 are in contact. It will be appreciated that this approximation may allow the contact area 308 between the sensor 306 and the materials 302, 304 to be considered as a single homogenous layer.

Although the contact region 308 in the model 300 is shown as a single homogeneous layer, it may be more accurately described as a series of layers having different thermal properties. It will be appreciated that a single layer approximation will hold true if the layers are thin enough and are heated for a long enough time.

As described above, the thermal contact model 300 may be used to measure and calculate various thermal characteristics of the materials 302, 304 and the contact region 308. For calculations and measurements made using the thermal contact model 300, the sensor 306 or heating element is located at x-0. It will be appreciated that the temperature at the sensor 306 follows equation 6:

where T (x) follows equation 7:

and R is_ijIs the reflection coefficient of a thermal wave (amplitude is temperature) from a first material into a second material.

As mentioned above, the width w₁And w₂May not be known because of theseWidth indicates that the contact region 308 is a thin region. It will be appreciated that equations 6 and 7 may be reconstructed to remove w₁And w₂As shown in equations 8, 9 and 10 below:

wherein t is_wIs the time constant for heat penetration. In some embodiments, the properties of the material 302 are known. Further, the temperature of the sensor may be fitted to the above equation using a non-linear fitting technique. It is understood that the non-linear fitting technique is performed for three-dimensional models and one-dimensional models.

Fig. 4 depicts an asymmetric thermal contact model 400 as a layered system. The asymmetric contact model 400 is similar to the thermal contact model 300, but with additional material 410 between the contact region 308 and the material 304.

The temperature of the sensor may be calculated in a manner similar to that described for the thermal contact model 300, but with a reflection coefficient R₂₃Is effectively reflected by coefficient R_e23Substitution, wherein:

it will be appreciated that the contact regions in the models 300 and 400 may be characterized by non-linear fitting, as described above. In some embodiments, there may be additional material next to material 304. In this case, the reflection coefficient R₃₄Will be reflected by the effective reflection coefficient R_e34Substitutions are calculated in the same way. In the further stepIn embodiments, there may be one or more additional materials next to material 302 and/or one or more additional materials next to material 304. This allows the thermal properties of any layered system to be determined by, for example, replacing the reflection coefficient accordingly. Such a hierarchical model or system may describe a system with a planar dimension much larger than a through-plane dimension.

The contact model described above may be used to determine thermal property values for the contact region and the material in the three-dimensional model. For example, materials such as polystyrene foam, stainless steel, etc. have been modeled using at least the contact model 100 described above. The results of the model are then iteratively analyzed using a non-linear fit over the entire data set to identify an approximation of the time constant (yL) for each test sample. The time constant can be used to determine a time window for a longer test time to determine the exact thermal properties of the material.

Contact model 100 may be provided as a three-dimensional model, with materials 102 and 104 being the same material and shaped as a disk, and sensor 106 also shaped as a disk as a planar transient source. On samples of extruded styrofoam as the material 102, 104 (fig. 5), on samples of expanded styrofoam with both a rough surface (fig. 6) and a cut surface (fig. 7), and on samples of stainless steel 304 with the surface rough ground (fig. 8), the sensor was heated at a constant power for a predetermined time of 10 seconds. On a sample of material 102, 104 (fig. 9) having polished surface stainless steel 304, the sensor was heated at constant power for a predetermined time of 0.5 seconds.

Fig. 5 depicts a graph showing the temperature of a thermal contact model using extruded polystyrene over 10 seconds. The graph depicts the temperature results of the contact model 502, the temperature of the disk source or sensor 504, and the contact corrections 506. It will be appreciated that these reference numerals are also used in fig. 6-9 to depict different results. In fig. 6-8, the temperature of the planar source 608 is also shown on the graph. It will be further appreciated that a planar source may be considered an infinite plane, while a disk source may be considered a finite radius. The disk source 504 may be a more accurate approximation of the temperature of the source.

In FIG. 5, F (t) andtc (t) are plotted as the disc source 504 and the contact correction 506, respectively, to show the effect of contact between material samples. F (T) is equal to equation 5 (T) shown above, regardless of the temperature of the contact between the materials_mdl(t)). The temperature result of the contact model 502 shown in the figure is the model (T) shown in equation 4 above_3D(t)) modified form.

It will be appreciated that at least the contact correction 506 plotted in fig. 5 for extruded polystyrene foam demonstrates a significant effect due to thermal contact of the material or material surfaces. These effects approach a constant temperature offset very slowly in a way that cannot be explained by a simple power reduction or temperature offset.

Fig. 9 depicts a graph showing temperature measurements using a thermal contact model of polished stainless steel 304 for 0 to 0.5 seconds. F (T) (disk source 504) and T are plotted_C(t) (contact correction 506) by the effect of contact between surface materials or the polished surface of the material. This can also be seen in fig. 8, which depicts temperature measurements for rough ground stainless steel. It will be appreciated that the effects of material contact or surface can be seen in fig. 8 and 9, particularly with respect to contact correction 506.

The method of determining the thermal properties of the contact region may be used to determine various other properties of the material and the model. For example, the method may be used to determine the time required for heat to penetrate from the sensor through the contact region to the second material, to correct the contact characteristics in measurements of bulk material characteristics, to automatically determine an appropriate time window for existing thermal measurement systems to minimize the effects of contact between materials, to calculate or determine the thermal characteristics of the film, and to calculate or determine the thermal characteristics of the layered system. The above-described model 100-400 can also be used to correct for finite and non-zero thermal characteristics of the sensor. It will be appreciated that the thermal capacity of the sensor is generally considered to be negligible and the thermal conductivity infinite. The present invention may eliminate the need for such an approximation.

The method of determining the thermal properties of the contact region may be implemented on a computer as a program for determining the thermal properties of the contact region, for correcting the contact properties in measurements of bulk material properties, for automatically determining an appropriate time window for an existing thermal measurement system to minimize the effects of contact between materials, for calculating or determining the thermal properties of a thin film, for calculating or determining the thermal properties of a layered system, and/or for correcting the finite and non-zero thermal properties of a sensor. When the above determination is performed on a computer, the computer may receive data relating to the temperature of the sensor over time. The computer may also receive data relating to known characteristics of the bulk material for analysis. The received data may then be used to determine a temperature profile of the heat of the sensor to the one or more materials. The temperature profile is then iteratively analyzed to isolate the thermal characteristics of the contact between the materials. Once the thermal characteristics are separated by iterative analysis, the computer can output these characteristics. Thermal characteristics of the contact region that may be output may include, but are not limited to, thermal conductivity, inverse thermal resistivity of the contact region, and heat capacity per unit area.

In other embodiments, the computer may isolate the thermal properties of the contact between the materials and then perform at least one of: the method includes the steps of correcting contact characteristics in measurements of bulk material characteristics, automatically determining an appropriate time window for an existing thermal measurement system to minimize the effects of contact between materials, determining thermal characteristics of a thin film, and determining thermal characteristics of a layered system. The computer may then output the corrected bulk material characteristics, the appropriate time window, the thermal characteristics of the film, the thermal characteristics of the layered system, and/or the corrected finite and non-zero thermal characteristics of the sensor.

Using the thermal contact model 100-400 described above, the thermal characteristics of the contact between materials can be isolated and analyzed, as described above. As depicted in fig. 5-9, contact has a significant impact on the transient planar source model. It will be appreciated that the thermal contact model 100-400 and the described method can be used to separate the contact heat from the bulk material thermal properties, which can stabilize the measurements of bulk material properties for different times and surface treatments.

The methods of determining thermal characteristics of a contact region described herein may use a time from the start of heating of the sensor to the time of transferThe heating time of the sensor ends the measured and calculated data. For the example in the figure, this means data from t-0 to t-10 seconds or t-0 to t-0.5 seconds. In the existing method, data must be limited to when the contact offset is constant. This means that in the analysis of existing systems, the data measured and calculated from the heating time should be deleted in order to be able to determine the exact thermal properties of the bulk material. Furthermore, in existing systems, the test must run long enough for the contact offset to be constant. The present method may allow all of the data to be used and does not require the sensor to be heated long enough for the contact offset to be constant. For example, the above method does not require t_LThe delay of (2). The heating time of the sensor can be shorter than in previous methods. Furthermore, the above-described model 100-400 may be capable of isolating and analyzing contact thermal characteristics independent of the sensor.

It will be appreciated that the above model and method may be particularly useful for insulators on which short test times are not sufficient to measure any thermal properties unless contact is considered. The measurement of the flow rate of insulators that do not follow this method is instead a measurement of the efficacy (effusance) because they are affected by the contact area characteristics and can change over time because the flow rate of bulk material starts to dominate.

It will be appreciated by those of ordinary skill in the art that the methods and assemblies shown in the figures and described herein may include components not shown in the figures. For simplicity and clarity of illustration, elements in the figures are not necessarily to scale and are merely schematic and not limiting in element structure. It will be apparent to those skilled in the art that variations and modifications may be made without departing from the scope of the invention as described herein.