JPS59145938A - Thermal flow sensor - Google Patents

Abstract

PURPOSE:To obtain a thermal flow sensor which can be manufactured easily and can measure all the conduction heat quantity by placing a material which is capable of moving a liquid by capillarity, on a coating material of the surface and the rear side of a rectifying sensor. CONSTITUTION:A filter paper 11 is stuck to the part extending from a rear side 10a of a thermal flow senser 10 to a surface 10c through one end side face. Water which becomes a watedrop on the rear side 10a by the filter paper 11 moves to the surface 10c by capillarity, and can be moved on the surface side. The thickness of the filter paper 11 is made thin enough to <=100mum so that influence is not exerted on a heat conductance C of the thermal flow sensor 10. A dummy 12 is made of black silicone rubber having the same quality of material as the coating material, and prevents water from evaporating from one end 10b of the sensor 10. In this way, water which becomes a waterdrop on the rear side 10a of the sensor 10 can be evaporated from the surface 10c, therefore, all the conduction heat quantities can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention describes the heat flow density (unit: i1/go・h or w /
This relates to a heat flow sensor that can be measured all at once.

Jointly, the heat flow density that transfers heat in an object (solid) is conducted by conduction, and the heat flow density dissipated from the surface of the object into the gas is transferred by convection and thermal radiation. Conventionally, a heat flow sensor is known as a measuring device for measuring such heat flow density, and this heat flow sensor is embedded in an object or attached to the surface of an object to measure the heat flow density radiated from the object. I'm trying to measure it.

As shown in Fig. 1, a heat flow sensor 1 normally detects the temperature difference between the front and back surfaces of a thin thermal resistor 2 using a detecting element 3 such as a thermopile or a differentially connected temperature measuring resistor (thermopile in the figure). It has a structure in which the front and back surfaces of the thermal resistor 2 are covered with covering materials 4 and 5 to protect it from mechanical mining and electrical disturbances (short circuits and noise). These heat flow sensors are introduced, for example, in ([Automation J June 1979 Vol. 24, Nu7, P-26-29, extra issue).

By the way, although the heat flow sensor described above can measure the amount of heat transferred by thermal conduction or by convection and heat radiation, it is completely unaware of the amount of heat transferred by evaporation of the liquid.

On the other hand, there is a desire to measure the amount of heat transfer dissipated from the human body, and more generally from a sweating animal, or there is a desire to measure the amount of heat transfer dissipated by the human body, or if there is water in the heating furnace and the amount of heat transferred as the water evaporates. The desire to know the amount of heat transferred has been rapidly increasing in recent years in various fields such as medicine, industry, agriculture, and architecture.

Therefore, the inventors of the present invention are able to measure the amount of heat transfer, which includes the amount of heat transferred by evaporation of liquid (unit: heat flow density). As a result of intensive experiments and studies to obtain a heat flow sensor that can also perform measurements, we have come to the following findings.Before explaining this finding, we will explain the conventional The measurement situation will be briefly explained.

FIG. 2 is a cross-sectional view showing how heat flow sensors la and ib are installed inside the object 6 and on its surface 6a to measure the amount of heat transferred by conduction, convection, and thermal radiation. In this figure, if the heat flow is a one-dimensional heat flow, the amount of conductive heat transfer is Q, the amount of convective heat transfer is qC1, the amount of radiation heat transfer is qr, then Q= qr + qc °−−”−”°−
゛°(1). That is, the heat flow density 1f1m measured by the heat flow sensor la embedded in the object 6 is also the same as that of the object surface 6.
The heat flow density in section 1 obtained by the heat flow sensor 1b attached to point a is also the same.

The heat flow sensor lb attached to the object surface 6a has its gas side surface colored to have an emissivity equal to the emissivity of the object surface 6a, and detects the temperature difference between the front and back surfaces of the thermal resistor 2.
When a thermopile is used as a thermoelectric stack, the heat flow density is calculated using the following relational expression. ([Journal of High Temperature Society J1978, 4, (2)
) Here, f(D)・C-1; value of thermal disturbance due to the attachment of the heat flow sensor λ; thermal conductivity of the thermal resistor d; thickness n of the thermal resistor; differential of the thermopile Number of thermocouples η; Thermoelectric power V of the thermocouple used in the thermopile; Output voltage of the thermopile; On the other hand, for the buried type heat flow sensor 1a, the following equation is obtained.

Here, F(D) is a coefficient including thermal disturbance, and when the thermal conductivity of the object and the thermal conductivity of the thermal sensor are equal, F(D)=1.

Note that in the field, a heat flow sensor 1b is often used, which is difficult to install and is installed by an installer on the object surface 6a. Therefore, in the following description, the case of a heat flow sensor installed on the object surface 6a will be explained as an example.

Next, the findings obtained by the Ministry of the Invention and others will be explained based on the conventional measurement situation described above. FIG. 3 shows the state in which heat is transferred as the reward moves due to evaporation from the surface 6a of the object 6. In the figure, qv indicates the amount of heat transfer due to evaporation.

In the conditions shown in Figures 2 and 3, the conventional heat flow sensor lb
In order to confirm what kind of output can be obtained when the material is attached to the surface of an object, an experiment was conducted using a constant temperature water bath 7 as shown in FIG. The water tank of this constant temperature water tank 7 has an inner diameter of 200,
It was cylindrical with a bottom, 75g high, and the water depth at this time was 50m. The upper part of this constant temperature water tank 7 was covered with mild steel plates 8a and 8b having a thickness of 250 mm x 2 mm. The mild steel plate 8a is 250
325 holes of 2 y + ml were drilled uniformly at 10-inch intervals on the entire surface of the 200 mm center part of the frame, and 8b did not have any through holes. The surfaces of both steel plates 8a and 8b were painted black. Mild steel plate 8a for these two buildings.

A heat flow sensor was attached to the surface of 8b, and a comparative study was conducted to determine what kind of output could be obtained when the water temperature was the same. Also,
The external dimensions of the heat flow sensor lb are 50. ．． ．． Horizontal 1
00. ．． ．． The material used was about 3 mm thick, the material to be treated was made of black silicone rubber, and the detection element was a thermoelectric stack of chromel/alumel. When this heat flow sensor 1b is calibrated using a separately prepared device that has a mild steel plate with a thickness of 5 mm and can generate a standard heat flow, the calibration constant is 1171 cal/m at 50 to 150°C.
” ·h-mV. Note that this standard heat flow generator M had a structure in which no water evaporated at all.

The constant temperature water tank 7 is kept constant at 60°C and 90°C, and the fourth
As shown in the figure, a heat flow sensor 1b was attached to the surface of each of the mild steel plates 8a and 8b, and the heat flow density of each was measured, and the result was as shown in FIG.

In the mild steel plate 8a, water vapor escapes upward through the two holes, and heat is carried away by it.
The indicated value of heat flow center/sl'b is as shown in the figure for mild steel plate 8.
It is the same value as b and remains unchanged. This is because the water vapor condenses on the surface of the heat flow sensor 1b on the mild steel plate 8a side and forms a mist, and since no water is emitted from the atmosphere side of the heat flow sensor 1b, the amount of heat radiated by evaporation is not detected. It is. On the other hand, in order to detect the amount of heat carried by this water vapor, a method may be considered in which, for example, several through holes are bored in the heat flow sensor lb, but this is useless. This is because the measurement principle of the heat flow sensor 1b is to obtain an output by detecting the temperature difference between the bottom and back surfaces of the thermal resistor. This is because the temperature difference mentioned above is not detected. Therefore, if evaporation is performed from the gas side surface of the heat flow sensor 1b, the temperature difference between the front and back surfaces of the thermal resistor changes depending on the amount of heat removed, and the amount of heat transfer due to evaporation can thereby be detected. .

Based on this, since evaporation only needs to be performed from the gas side surface of the heat flow sensor 1b, for example, cloth, paper, or a porous material is adopted as the thermal resistor material of the heat flow sensor 1b, and the heat flow sensor 1b is One possible method is to move the water once condensed on the surface of the mild steel plate 8a to the gas side surface of the heat flow chamber by capillary action, and re-steam it from that surface, but this method cannot be adopted either. That is (2) above.
, when measuring the amount of heat transfer due to convection and thermal radiation as shown in equation (3), even though it is required that the thermal conductivity λ of the material of the thermal resistor does not change (is constant), If the resistor material is a porous negative material that absorbs moisture, its thermal conductivity will be about an order of magnitude higher (for example, from Q, 05kcal/(m・h・'C)) between when it absorbs moisture and when it is dry. o, sb + 7'< m - h - °C), and such a heat flow sensor is of no use.

Here, we have come to the conclusion that the above-mentioned difficulties can be overcome by disposing a material that causes capillary action on the substrate of the heat flow sensor 1b.

The present invention has been made based on the above findings. That is, the present invention removes a thermal resistor and a detection element that detects the temperature difference between the front and rear surfaces of the thermal resistor, and moves a liquid (mainly water) onto each of the front and back core materials by a storage movement phenomenon. In addition, the front and back materials are connected to each other using the liquid as a medium.

In the present invention, filter paper, case, etc. are suitable as the material that moves the liquid by a storage movement phenomenon such as capillary action, and the material that does not cover the entire surface of the covering material is, for example, a degreased thread. Another possible method is to sew it onto the covering material in a sashiko-like manner. In short, the material for mass transfer and evaporation in the present invention may be any material as long as it can quickly move the liquid condensed on the surface to be measured (back surface) of the heat flow sensor to the surface of the heat flow sensor.

Further, when the above-mentioned material is applied to the gas side surface of the heat flow sensor, it is better not to cover the entire surface tightly. The reason is as follows. In other words, when measuring the amount of heat transfer that involves thermal radiation, is it necessary to match the emissivity of the surface to be measured and the gas side emissivity of the heat flow sensor? It is necessary to However, as is well known, the emissivity of a material that has absorbed moisture approaches approximately 1 due to the influence of moisture. Therefore, if the entire surface of the heat flow sensor is densely covered with such a harmful material that absorbs moisture, the emissivity of this heat flow sensor will always be 11, which is close to 1, when moisture is absorbed. . In this state, for example, when measuring the amount of heat dissipated from a shiny metal surface (the emissivity of a shiny metal surface is about 0.1, for example), it is necessary to rate is 0
．． Even if it is set to be about 1, the emissivity becomes a lull close to 1 when measuring the amount of heat transfer accompanied by evaporation. Therefore, even if the heating center is configured to accurately measure the amount of heat transferred by convection and the amount of heat transferred by evaporation, the remaining amount of heat transferred by radiation will be overestimated. This is because, as a result, measurement errors occur when evaluating the total heat transfer amount of the object.

To overcome this difficulty, it would be best to take measures such as sewing as described above.

In the present invention, liquid is transferred to IHjl by capillary action.
J? Since the material that can be used as water droplets is placed from the nucleated material on the & side of the heat flow sensor to the covering material on the front side, it is possible to evaporate the liquid that has become water droplets on one side of the heat flow sensor.
Thereby, the total amount of heat transfer, which is the sum of the amount of heat transfer due to convection and thermal radiation plus the amount of heat transfer due to evaporation, can be easily evaluated. Furthermore, the heat flow sensor of the present invention has a structure in which a material that can move liquid by storage movement phenomena such as capillary action is provided from the back side to the front side of the conventional heat flow sensor, so it is easy to manufacture and has a low manufacturing cost. It requires less and is highly practical.

Furthermore, even if the heat flow sensor according to the invention is embedded in porous objects such as powder or bricks, even if liquid moves within these porous objects, the liquid will not move as described above. is carried from one side of the heat flow hinge to the other,
As a result, the total amount of heat transfer including the amount of heat transfer accompanying the movement of the liquid can be easily measured.

Next, the present invention will be further explained and evaluated by examples.

〔Example〕

In FIG. 6, numeral 10 indicates a heat flow sensor,
This heat flow sensor IO has the same configuration and the same dimensions as the heat flow sensor lb described above. A filter paper 11 is pasted from the back surface 10a of this heat flow sensor IO to the front surface 10c via one side end 10b. This filter paper 11 causes capillary action and is used as a material to help increase the thickness, and its thickness is approximately 200 μm. With this filter paper 11, water that has become droplets on the back side of the heat flow sensor can be moved to the front side by the capillary phenomenon, and can be evaporated from the front side.

Filter paper 11 present at one end 10b of the heat flow sensor IO
The area in the surface 10c direction of the heat flow sensor 10 is the area of the surface 10c of the heat flow sensor 10.
0.2 for the total area of c 50 x 100 mm
x 100va, which is extremely small. Therefore, even if the thermal conductivity of the filter paper 11 in this portion changes between when absorbing moisture and when changing the line, it can be considered that the thermal conductance C of the heat flow sensor 1O does not change. Note that due to the ceramic paper 11 existing on the front and coplanar surfaces of the heat flow sensor 10, the thickness of the heat flow sensor 10 increases by about 10% from about 3 mm to about 3.4 mm. Therefore, the heat flow sensor 10 due to the fact that the thermal conductivity of the filter paper 11 changes when it absorbs moisture and when it dries.
The influence on the total thermal conductance C and further on the final calibration constant is estimated to be about 10%, which is a somewhat large influence. Therefore, in order to put the present invention into practical use, it is necessary to make the thickness of the filter paper 11 very thin. In a practical heat flow sensor, it is necessary to use a filter paper as thin as 100 μm or more in order to ensure sufficient absorption for measurement.

In addition, in the figure, the reference numeral 12 indicates one end 10b of the heat flow sensor 10.
This figure shows the dummy set in the figure. This dummy 12 is made of black silicone rubber made of the same material as the material to be treated in the heat flow sensor 10, and is used to prevent water from evaporating from one end 10b of the heat flow sensor 10. Therefore, this dummy 12 is useful if it can prevent evaporation at one end 10b of the heat flow sensor 10, and when the thickness of the heat flow sensor 10 is thin, evaporation at the negative end 10b is negligible. Therefore, it is not necessary to provide it.

Next, a detection formula for determining the amount of heat transfer using the heat flow sensor 10 having the above configuration will be explained. In the heat flow sensor 10 described above, the condensed liquid is transferred from the back surface 10a to the front surface 10c of the heat flow sensor 10 due to storage movement phenomenon, and the amount of heat dissipated due to evaporation is measured by the heat flow sensor 0. The relational expression for detecting M-scenes is determined as follows.

λ q v = −−V ”°°…゛1゛°°゛…°°”
°(4)dnη Therefore, when detecting the sum of heat transfer due to evaporation, convection, and thermal radiation, the correct detection formula for the total amount of heat transfer is based on equation (4) and equation (2) above. ... (5) 8 However, in reality, the output is (Vt+
(2) Since it is output all at once, the total amount of heat transfer can be expressed in the following format.

qv+qc+qr,=A (L+ +v,)...
...-(6iA; Average calibration constant of heat flow sensor Here, if we compare and consider the above equation (5) (61), for example, the above 1iaAl is 11° which corresponds to λ/'dnη, that is, If you give the calibration constant A when calibrating the standard heat flow generator so that the known heat flow density flows directly to the heat flow sensor 0, you will end up giving a small amount to the correct detection tube.On the other hand, Calibration constant when heat turbulence occurs in a heat flow generator, that is, f(D)・c 1
The value A1 is calibrated to obtain the calibration constant that says
If you use this, you will end up giving a large shift to the correct maid.

Therefore, as a heat flow sensor for practical use, a sensor with a large total thermal conductance C is manufactured, and the imf of thermal turbulence is
(D)・0-' can be made extremely small by measurement f%1
It is necessary to secure m. When the thermal disturbance I(D)·a 1 cannot be ignored, it is practical to use the arithmetic mean of Ao and A described above.

A calibration constant A s a of the heat flow sensor lO during drying;
The result of comparing the calibration constant A+b (both calibration constants Ata and Alb are calibrated under conditions that take into account thermal turbulence) without the filter paper 11 (conventional heat flow sensor lb) is shown in the seventh table. As shown in the figure. In addition, this figure shows a diagram 111A in which the heat flow sensor 1b is calibrated under conditions without heat turbulence. are also shown. The calibration constants calibrated under conditions with thermal turbulence are the same as those of the conventional heat flow sensor 1 in the heat flow sensor
The cage is approximately 13 inches larger than B, indicating that it is more difficult to open quickly. Here, when measuring the amount of heat transfer without evaporation, the average calibration constant is A = 1327.
/rrt・h”inv is used to measure the amount of heat transfer accompanied by evaporation, and the average calibration constant is A-(117+98)/2.
= 108 kcal/7rL · h-mV is used.

The results of an experiment using the heat flow sensor 10 described above using the constant temperature water bath 7 shown in FIG. 4 are shown in FIG. 8 (corresponding to FIG. 5). In the case of the mild steel plate 8b, the results match well with the results shown in FIG. In other words, since there is no transfer of heat due to water evaporation, it is determined that showing matching boxes gives the correct result. However, as shown in the figure, the heat flux sensor 10 is laminated on the surface of the mild steel plate 8a, and the radiated heat is approximately 2.2 to 2.3 times as large as the temperature of the surface to be measured, as shown in the figure. It has become. In other words, the amount of heat transferred by radiation and convection is almost equal to the amount of heat transferred by evaporation of water, and the conventional heat flow sensor 1
b It became quantitatively clear that the heat transfer 11: accompanied by evaporation cannot be evaluated as it is, and the effectiveness of the heat flow sensor 10 of the present invention became clear.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an example of a conventional heat flow unit, Fig. 2 is an explanatory diagram of a conventional heat flow density measurement situation, Fig. 3 is an explanatory diagram of a heat transfer state when there is evaporation, and Fig. 4 is an explanatory diagram of a heat transfer state when there is evaporation. Figure 5 is a diagram showing the configuration of a constant-temperature water tank for experiments, Figure 5 is a graph showing measurement results using a conventional heat flow sensor using the experimental apparatus shown in Figure 4 with and without evaporation, and Figure 6 is a graph showing the results of measurements made using the present invention. FIG. 7 is a graph showing the relationship between the calibration constant and temperature of the conventional heat flow sensor and the heat flow sensor of the present invention frozen by a standard heat flow generator, and FIG. 8 is a perspective view showing an embodiment of the heat flow sensor according to 5 is a graph showing the measurement results of the amount of heat dissipated by the heat flow sensor of the present invention performed in the experimental apparatus of FIG. 4. FIG. 2... Heat resistor, 3... Detection confectionery, 4, 5... Covering material, 6... Object, 11... Filter paper (material that can move and stir the adult body through the mobilization movement phenomenon) . Applicant Showoro Electric Works Co., Ltd. Figure 1, Figure 2, Figure 3, Figure 5, Figure 11! Favor 1, Evening Figure 6

Claims (1)

[Claims] A heat flow hinger for measuring heat flow density dissipated from an object, which includes a thermal resistor, a detection element that detects a difference in temperature between the front and back sides of the thermal resistor, and a covering material that protects these front and back surfaces. , A material capable of moving a liquid by a storage movement phenomenon is disposed on the front side covering material and the back side covering material, and each material of the lining is connected using the liquid as a medium. The heat flow is amnesty for what has been constructed.