JPS6038646B2 - emissivity measurement method - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an emissivity measurement method, and more specifically, when measuring the heat flow east from the surface of a fixed object on the east side of the heat flow using a heat flow sensor that measures the heat flow east, the present invention relates to an emissivity measurement method, and more particularly, when measuring the heat flow east from the surface of a fixed object on the east side of the heat flow, even if the emissivity of the object to be measured is unknown. Since this will cause measurement errors, the emissivity of the object to be measured must be known in advance. Generally, emissivity is described in data books and other documents, but there are only a few studies on emissivity with respect to temperature changes. The present invention relates to an emissivity measurement method in which an unknown emissivity can be determined by using an emissivity measuring element having a known emissivity. As the emissivity measuring element having a known emissivity as described in the present invention, an element formed on the surface of a thin aluminum plate by adjusting the thickness of the anodic oxide film so as to have an emissivity within a predetermined range can be used. The rate has been found to have a small temperature dependence. A heat flow sensor refers to a structure in which a detection element for detecting the temperature difference between the front and back sides of a thin film thermal resistor and a detection element for measuring the surface temperature are incorporated between an electrically insulating thin film body. When measuring the heat flow east ◇ using a heat flow sensor for a measured object that emits heat flow east (g: Kcal/〆・h),
In principle, when the temperature difference △T (00) between the front and back sides of a thermal resistor is measured with a DC voltage output V using a temperature difference measurement detection element (differential thermocouple group), the following formula ○=VX^/d (ri=V/
△TmV/℃) However, input: Thermal conductivity of the thermal resistor d: Thickness of the thermal resistor: The heat flow east ◇ is determined by the thermopower of the differential thermocouple group, but the When considering the radiated energy of the two, if their emissivities differ, measurement errors will occur. Therefore, in order to accurately measure the heat flow east of the object to be measured, it is necessary to establish the relationship between the emissivity o of the surface of the object to be measured and the emissivity a of the atmospheric side surface of the heat flow sensor. is necessary. Therefore, the emissivity o of the surface of the object to be measured must be known in advance. In addition, when measuring the surface temperature of an object using an infrared radiation thermometer, it is necessary to know the emissivity of the object's surface. However, although the emissivity of various materials is described in literature, the value of emissivity when the temperature changes is not often described. As a method for measuring the above-mentioned emissivity, the following measurement method is usually adopted. The principle of the measurement method follows the following formula. Q = Go. TS4 However, Q: Amount of heat dissipated from the surface of the measured object. : Stephan's constant Ts: Temperature of the surface of the object to be measured [1] Measure the surface temperature Ts(k) of the object to be measured with, for example, an Atsuka-type infrared thermometer, The value of the emissivity correction mm (which can be corrected up to 1.0) is varied so that the temperature indicated by the thermometer becomes the temperature Ts measured separately with a contact thermometer, and the value indicated by the emissivity correction mm is adjusted accordingly. is the emissivity of the surface to be measured.

[0] The intensity distribution of the radiation spectrum of the surface of the object to be measured is measured by infrared spectroscopy, and the emissivity is calculated from this. An object of the present invention is to provide a simple and highly accurate measurement method that is different from the conventional emissivity measurement method for a measurement object. Hereinafter, the emissivity measurement method of the present invention will be explained with reference to the attached principle diagram. Four emissivity measuring elements (1 to 4) whose emissivity at the radiation temperature TR is known are attached to the surface of the object to be measured. This state is shown in FIG. In the figure, 1 indicates an emissivity measuring element, and 2 indicates an object to be measured. After each of the emissivity measurement elements 1 is attached to the surface of the measurement object 2, and after they reach a steady state, emissivity correction is not performed using, for example, a dew-type infrared radiation thermometer as a radiation temperature measurement element, i.e. Assuming that each emissivity is 1, the emissivity measuring element M. Measure the radiant temperature TR from 1 to 4. The functional relationship between each emissivity at the surface temperature Ts of the object to be measured and the radiation temperature TR of the emissivity measuring element is determined, and a calibration curve is drawn as shown in FIG. Next, the radiation temperature TR of the object to be measured. is measured with an infrared radiation thermometer. This measured temperature T
By placing Ro on the calibration curve, the emissivity for that temperature can be determined. EXAMPLE Stainless steel (SUS) was used as the object to be measured, and its emissivity was measured. The emissivity measurement element having a known emissivity was an aluminum substrate on which an anodic oxide film was formed using the sulfuric acid alumite method. Five of these elements were pasted at equal intervals on the surface of the SUS plate, and
After the temperature of the emissivity measuring element reached an equilibrium state with the temperature of the plate, the radiation temperature TR of each emissivity measuring element was measured using an infrared radiation thermometer with no emissivity correction.
The relationship between this measured temperature TR (K) and each known emissivity of the emissivity element is as shown in the following table.・Next, I made the following preparations as a preliminary step to discussing the accuracy of determining the emissivity of a SUS plate with unknown emissivity. The surface temperature Ts of the above emissivity measurement object measured with a contact thermometer is approximately 120 pm, although it varies slightly each time the TR of each element is measured (Ts in Table 2). This temperature Ts can also be determined from the following equation if the room temperature T^ is known for each emissivity. That is, TS4=(TR4-T^
4)/Go+T^4 Next, the emissivity of the element and the object to be measured was determined from the following relational expression using Ts measured with a contact thermometer and listed in Table 2. Go=(TR4-T^4)/(TS4-T^4)×100
(%) The emissivity (%) calculated from Ts measured with the contact thermometer shown in the upper table of Table 2 is approximately approximate to the known emissivity (%) of the emissivity element shown in Table 1. It was confirmed that there was no compromise with the known value. Next, FIG. 2 shows a diagram of a calibration curve based on the measurement results listed in Table 1. From the same calibration curve, the radiation temperature of SUS TRo (°C) = 35.
When the emissivity of 70 was calculated, it was 10.05%, which was in good agreement with the calculated value of 35.700 (TR), which was 10.13%. According to the measurement method of the present invention, it is possible to easily and accurately measure the emissivity of the surface of an object such as a target object on the east side of heat flow using two or more emissivity measurement elements having known emissivity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the principle of the measuring method of the present invention, and FIG. 2 is a calibration curve diagram used for measuring SUS (stainless steel). Figure 1 Figure 2

Claims (1)

[Claims] 1 At least two or more emissivity measurement elements having a known emissivity ε are attached to the surface of the emissivity measurement object, and after reaching a steady state, the radiation temperature T_R of the emissivity measurement element and the measurement object are measured. The radiation temperature T_S of the emissivity measurement element is measured by each radiation temperature measurement element, and the radiation temperature T_S of the emissivity measurement element is measured by the radiation temperature measurement element.
The emissivity ε of the object to be measured is determined by the functional relationship between R and the emissivity ε.
An emissivity measurement method characterized by determining o.