GB 11833-1989 Determination of steady-state heat transfer properties of thermal insulation materials - Ball method
Some standard content:
a. The average temperature rise in the furnace shall not exceed 50℃;
b. The average temperature rise on the surface of the sample shall not exceed 50℃;℃. The average temperature rise at the center of the sample shall not exceed 50℃; d. The average continuous burning time of the sample shall not exceed 20s; e. The average weight loss rate of the sample shall not exceed 50%.
VII. Thermal insulation materials for construction
For non-thermally stable materials that shrink or melt obviously, the data recorded by the sample thermocouple is meaningless and can not be used as a judgment condition.
8 Test report
The test report shall include the following contents:
α. Name of the entrusting unit;
b. Name of the production unit;
c. Name and mark of the material;
d. Material properties;
e. Material supply date and test date;
f. Observed phenomena;
g. Test results and appraisal opinions;
h. Test unit and person in charge.
Additional Notes:
This standard was proposed by the Ministry of Public Security of the People's Republic of China. This standard was drafted by the Sichuan Fire Science Research Institute of the Ministry of Public Security. 9. "Spherical Method for Determination of Steady-State Heat Transfer Properties of Insulating Materials" GB11833-89 When the spherical method is used to determine the steady-state heat transfer properties of insulating materials, the heat flux emitted by the inner ball is radially transmitted to the outer ball through the test material. There is no lateral heat loss and back heat loss (single specimen method) in the protective hot plate method. The theoretical error is small, and the structure and operation of the measurement device are relatively simple. Therefore, the spherical method is a better method for determining the heat transfer properties of granular insulating materials. Granular insulating materials are typical porous materials. The characteristics of their heat transfer properties are that in addition to solid conduction heat transfer, there are also gas conduction, radiation and convection heat transfer. Therefore, the measurement result is the comprehensive heat transfer property of the material being measured, which is called the apparent thermal conductivity. The above factors must be fully considered when using the measurement results. 1 Subject content and scope of application
This standard specifies the technical requirements and measurement methods for the device for measuring the steady-state heat transfer properties of granular (or powdered) materials using a spherical heat transfer device.
This method is only applicable to the measurement of dry materials. The measurement range of the apparent thermal conductivity of the specimen is 0.02~1.0W/m. The measurement result of this method is the apparent thermal conductivity of the specimen under a given average temperature and temperature difference. When the apparent thermal conductivity is independent of the measurement temperature difference, the measurement result is the average measurable thermal conductivity of the specimen. When the radial dimension of the specimen (the difference between the outer and inner sphere radii) is greater than the minimum thickness required to determine the thermal conductivity of the material being measured, and the measurement result is independent of the measurement temperature difference, the measurement result is the thermal conductivity of the material.
Note: If the minimum thickness of the specimen for determining the thermal conductivity of the material is unknown, the minimum thickness of the specimen should be determined in accordance with the provisions of Appendix B of GB10294. 2 Reference standards
GB4132 Terminology of thermal insulation materials
GB10294 Determination of steady-state thermal resistance and related properties of thermal insulation materials Guarded hot plate method 3 Terms, terms and symbols
3.1 The following terms are quoted from GB4132
3.1.1 Heat flow Q (W).
3.1.2 Thermal conductivity [W/(mK)].
3.2 Other terms
3.2.1 Thermally stable body
The thermal conductivity of an object, λ or [λ], is not a function of time, but can be a function of the position, direction and temperature in the object. 3.2.2 Apparent thermal conductivity λ.
The value calculated by the thermal conductivity formula from the data measured under the combined action of three heat transfer mechanisms including conduction, convection and radiation. This value varies with the measurement conditions (measurement temperature difference, specimen thickness, radiation characteristics of the boundary surface, etc.). 3.2.3 Samples
Sampling is done according to the method specified in the standard of the material to be tested, and the number of samples is reduced to a slightly larger number than that required for the test. 3.2.4 Test piece
The sample is loaded into the test device for testing. 4 Principle
The spherical heat transfer device consists of a concentrically arranged heating inner ball and a cooling outer ball. Its structural principle is shown in Figure 1. When the temperatures of the inner and outer balls are stable, the heat flux Q emitted by the inner ball is radially transferred to the outer ball through the test piece, and the heating power of the inner ball, the temperature of the outer surface of the inner ball and the inner surface of the outer ball, and the geometric dimensions of the ball are measured to calculate the apparent thermal conductivity of the material to be tested. The calculation formula is as shown in formula (1). Q×D2-D×1
a=T,-T,*D,xD*2元
In the formula,
-apparent thermal conductivity of the material being tested
(W/(m·K));
the heat flux emitted by the inner sphere, which is numerically equal to the electric power applied to the inner sphere heater (W);-outer diameter of the inner sphere (m);
D2inner diameter of the outer sphere (m);
Figure Schematic diagram of the spherical device
B1-inner sphere;B2-outer sphere;Ci-inner sphere temperature measuring thermocouple;C2-outer sphere temperature measuring thermocouple;H-heater;S-support tube;T-feeding port cover;D1-inner sphere outer diameter;D2-outer sphere inner diameterT,-inner sphere outer surface temperature (K);
T2--outer sphere inner surface temperature (K).
5 Device
5.1 Technical requirements of the device
5.1.1 Size of the device
VII. Thermal insulation materials for buildings
The size of the device depends on the particle size of the material to be measured. Half of the difference between the inner diameter of the outer sphere and the outer diameter of the inner sphere [(D2-D,)/2] should be at least 10 times the particle diameter of the test piece. The ratio of the inner diameter of the outer sphere to the outer diameter of the inner sphere is recommended to be between 1.4 and 2.5.
5.1.2 Heating unit - inner sphere
The inner sphere is a hollow thick-walled sphere made of a metal material with a high thermal conductivity. The spherical surface should not react chemically with the test piece and the environment at the working temperature. The outer surface of the sphere should be processed to a roundness less than ±0.2% of the outer diameter. During operation, the temperature non-uniformity of the inner sphere surface should be less than ±2% of the temperature difference between the inner and outer spheres. All working surfaces should be processed so that the total hemispherical emissivity at the working temperature is greater than 0.8. An electric heater is installed in the cavity of the inner sphere. The heater is made into a spherical shape with an insulating bracket. The heater lead wire should be connected in a four-wire system at the outlet of the inner sphere to accurately measure the heating power of the inner sphere. Copper wire should be avoided as the lead wire to prevent significant errors caused by heat dissipation of the lead wire. The material and diameter of the current and voltage wires are properly selected, and the heat generated by the current wire compensates the heat transfer loss of the voltage wire, which can minimize the error caused by the heat transfer of the wire. 5.1.3 Cooling unit - outer sphere
The outer sphere should be divided into upper and lower hemispheres. There should be a feeding hole on the top of the upper hemisphere, and the feeding hole should be equipped with a sealed cover. When the area of the feeding hole is large, special measures should be taken to prevent its temperature from deviating from the temperature of the outer sphere. The outer sphere should be controlled at a constant temperature lower than the heating unit. The temperature non-uniformity of the inner surface should be less than 2% of the measured temperature difference. The metal sphere can be kept constant by passing a constant temperature fluid. When the temperature is high, an electric heater can also be used for temperature control or both. The hemispherical emissivity of the inner surface should be greater than 0.8. The inner and outer balls should be kept concentric, and the eccentric distance should be less than 2.5% of the outer diameter of the inner ball. A support tube can be used to keep the inner and outer balls concentric to prevent the inner ball from deforming the specimen due to its own weight. The support tube should be made of low thermal conductivity material and its cross section should be as small as possible. In any case, the heat transferred by the support tube should be less than 5% of the heat generated by the inner ball. The apparent thermal conductivity should be calculated according to formula (4).
If the outer ball temperature is lower than the dew point of the ambient air, an "O\-ring or other sealing measures should be set at the joints of the upper and lower hemispheres of the outer ball and the cover to prevent the specimen from absorbing moisture. 5.1.4 Protective cover
In order to reduce the impact of indoor air fluctuations on the outer ball temperature, the spherical part should be isolated from the indoor air by a protective cover. When the outer ball temperature is significantly higher or lower than room temperature, an insulation layer should be set inside the protective cover. 5.1.5 Measuring instrument
5.1.5.1 Temperature measurement sensor. The inner and outer ball temperatures are measured by thermocouples buried in the inner and outer balls or in the grooves on the spherical surface. The diameter of the thermocouple wire should be less than 0.3mm. The error limits of all thermocouple wires should meet the requirements of the special grade in Appendix B. Otherwise, they should be calibrated and screened separately, and a thermoelectric comparison table should be prepared. Copper-Constantan should be avoided Thermocouples. The number of thermocouples buried in the inner sphere shall be no less than four, with two in each of the upper and lower hemispheres. The location of the thermocouples should avoid the support tube and the joints between the upper and lower hemispheres where the temperature field may be distorted. The number of thermocouples buried in the outer sphere is the same as that in the inner sphere. The inner and outer sphere thermocouples can also be connected in a temperature difference type to directly measure the temperature difference between the inner and outer spheres. In this case, the thermocouples must be electrically insulated from the inner and outer spheres. 640 Part 1 Testing Method Standard for Main Building Materials 5.1.5.2 Temperature Measuring Instruments. The sensitivity and accuracy of the temperature and temperature difference measuring instruments shall be better than ±0.2% or ±0.1°C (the larger one) of the temperature difference.
5.1.5.3 Power Measuring Instruments. The sensitivity and accuracy of the inner sphere heating power measuring instrument shall be better than ±0.1%. 5.1.6 Temperature Control System
5.1.6.1 The inner ball heating method can be constant heat flow method or constant temperature method. When the constant heat flow method is used, the fluctuation of the heating voltage should be less than ±0.1%, and the drift every 2 hours should be less than ±0.1%. When the constant temperature method is used, the test error caused by the temperature fluctuation and drift of the outer surface of the inner ball should be less than 0.3%. The fluctuation of the heating power should be less than ±0.3%. The constant temperature method can significantly shorten the test time.
5.1.6.2 The temperature control system of the outer ball should control the fluctuation and drift of the inner surface temperature of the outer ball to be less than 0.3% of the temperature difference. 5.2 Inspection of the device
5.2.1 Geometric dimensions: Check the outer diameter and roundness of the inner ball; the inner diameter and roundness of the outer ball. Check the concentricity of the inner and outer balls. 5.2.2 Electrical insulation. Measure the electrical insulation of the electric heater to the ball (should be greater than 1MQ). If the temperature difference connection method is used, the electrical insulation of the thermocouple to the ball should also be checked. And the measurement must be repeated at both ends of the working temperature range. 5.2.3 Temperature measuring instrument. The sample cavity of the sphere is filled with low thermal resistance material and thermal equilibrium is maintained at room temperature. The indication of the inner and outer thermocouples should be very close to the room temperature, and the interference voltage should be within the instrument noise voltage range. The expected maximum working voltage of the heater is added between the sphere and the heater, and the change in reading caused by this should be less than the allowable error of temperature measurement (see 5.1.5.2).
The outer sphere is heated and maintained at the maximum working temperature, and the inner sphere is not heated. At thermal equilibrium, the inner and outer thermocouples should indicate the same temperature, and the difference should be less than the sum of the thermocouple screening deviation (see 5.1.5.1) and the allowable error of the temperature measurement system (see 5.1.5.2).
Temperature control system inspection. The sample cavity of the sphere is filled with low thermal conductivity material, and the measurement is carried out with the minimum temperature difference designed by the device. Check the fluctuation and drift of the inner sphere temperature. When the constant temperature method is used, the fluctuation and drift of the heating power should also be checked. Then use the material with the maximum thermal conductivity coefficient predetermined when designing the device, and measure it with the maximum temperature difference to check the uniformity of the temperature of the inner and outer balls and the fluctuation and drift of the outer ball temperature. Repeat the above test at both ends of the device's operating temperature range. 5.2.5 Use the thermal stability material measured by the national recognized laboratory for measurement, and the measurement error should be less than the design error. After the above inspection, the device can be officially used. The stability of the device should be checked regularly. 6 Test piece preparation
6.1 The sample should be sampled and reduced to the required number according to the method specified in the product standard of the material being tested. 6.2 The particle size of the uniform particle size material should be less than one-tenth of the thickness of the test layer. For mixed graded materials, when the content of large particle materials is less than 10%, the diameter of the largest particle can be relaxed to one-fifth of the thickness of the test layer. 6.3 The sample should be adjusted to a constant state (4h mass change is less than 0.5%) in a ventilated oven at (105±5)℃. The dried sample should be placed in a desiccator for cooling and standby. 6.4 Determine the loose density of the sample according to the method specified in the product standard of the material being tested. 6.5 Prevent the sample surface from being contaminated during sample preparation, especially for samples with higher thermal conductivity. 7 Determination steps
7.1 Loading the test piece
Calculate the mass of the test piece to be loaded according to the volume of the test cavity of the device and the density during measurement. The density during measurement is generally 1.10 times the loose density. Weigh the sample and divide it into two parts. First open the upper hemisphere and load the lower hemisphere, with the loading amount being half of the mass of the test piece. Then install the upper hemisphere and load another sample from the feeding hole on the top of the ball. The test piece should fill the cavity, paying special attention to the fact that there should be no gaps at the top.
Weigh the mass of the sample before loading and the remaining mass after loading to determine the mass of the test piece. Its accuracy should be better than ±0.5%.
7.2 Temperature difference selection
The heat transfer properties of granular materials are related to the temperature difference. The temperature difference is determined according to the following selections. a. Requirements in the material product standard;
b. The use conditions of the test piece;
c. When determining the relationship between the unknown temperature and the heat transfer properties, the temperature should be as low as 10~20K as possible; d. When the mass transfer phenomenon in the test piece is required to be minimized, the lowest temperature difference is selected according to the accuracy required for the temperature difference measurement, which may mean that it does not conform to this standard.
Note: When the spherical device is measured, the temperature gradient at different radii of the test piece is different. The temperature gradient at the outer surface of the inner sphere is R,-R*,AT×登,外
T×, and the average temperature gradient is △T/(R2-R1) (R is the outer radius of the inner sphere, and the temperature gradient at the inner surface of the sphere is R,-R*R2R2 is the inner radius of the outer sphere). If the apparent thermal conductivity of the specimen is not linearly related to the temperature, the range of the actual temperature gradient should be considered when selecting the measured temperature difference to prevent significant errors. 7.3 Control of the inner surface temperature of the outer sphere
Adjust the liquid flow or electric power of the upper and lower hemispheres to control the temperature of the upper and lower hemispheres so that the temperature difference between the upper and lower hemispheres does not exceed 1% of the measured temperature difference.
7.4 Determination of heat flow
The heat flow of the inner sphere heating is numerically equal to the electric power applied to the inner sphere heater. Measure the average power applied to the inner sphere heater with an accuracy of ±0.2%. 7.5 Transition time and measurement interval
In order to obtain the correct value of the thermal properties, the device and the specimen must have sufficient thermal equilibrium time. The thermal equilibrium time is related to the structure, control method, geometric dimensions of the device and the thermal properties of the specimen. After the constant temperature device rises to the predetermined temperature, and then continues for [(2t
［/D2-D1)2
/α time, the specimen can enter a stable state. Among them, α is the thermal diffusion coefficient (thermal conductivity) of the specimen, and its value can be obtained according to experience or from the manual. After entering the steady state, the power applied to the inner ball heater and the inner and outer ball temperatures are measured at a time interval of 0.2t. The test ends until the difference in thermal properties given by four consecutive sets of readings does not exceed 1%, and does not change monotonically in one direction, and the error caused by the drift of the inner ball temperature is less than ±0.3%. 8 Calculation
8.1 Packing density
The packing density of the specimen can be calculated based on the mass of the specimen weighed and loaded into the specimen cavity and the volume of the specimen cavity in Article 7.1.
(DD）
Where p——density of the specimen (kg/m2);
Part I Test Methods for Main Building Materials Standard specimen mass (kg).
8.2 Change in mass
Calculate the relative change in mass of the specimen during the adjustment process based on the mass of the specimen before and after state adjustment: m=
Where m—
-relative change in mass before and after adjustment (%); M,——mass of the specimen before adjustment (kg); M2mass of the specimen after adjustment (kg).
8.3 Calculation of heat transfer properties
Calculate the heat transfer properties using the average of the four sets of readings tested in 7.5. Other additional readings may also be used for calculations as long as the difference is less than ±1%.
The apparent thermal conductivity of the specimen is calculated according to formula (4): α\F'D2- D1
Q(D2 D)
2 yuan (TT,) D,·D,-2 yuan L×
D2·Di
wherein — the apparent thermal conductivity of the specimen (W/(m·K)); >' — the thermal conductivity of the support tube material (W/(m·K)); F — the cross-sectional area of the support tube (m2);
L — the length of the support tube (in general, its value L=(Dz -D,)/2)(m). 8.4 Average temperature
The average temperature T during the measurement is calculated using the average value of the measurements in 7.5. ()2-1| ×(
T-T+T2_T-TJ
９Report
The report of the measurement results should include the following items:2
(D2/D1)3 -1
a. Material name, mark and physical property description (such as particle size distribution, etc.); b. Conditioning method and temperature;
c. Loose density of the sample after conditioning; d. Density of the sample during measurement;
e. Average temperature and temperature difference during measurement;
f. Thermal property values and their applicable temperature difference range; g. Date and duration of measurement;
h. Dimensions of the device;
1. If necessary, provide a graph or table with the thermal property values as the ordinate and the corresponding test average temperature as the abscissa; j. Provide the maximum expected error of the measured thermal property values; (4)
. If some requirements in the measurement process do not meet the requirements of this standard, the following statement should be made in the report: "Except for this, all meet the requirements of GB11833." A1 Eccentricity error
Appendix A
Error estimation
(Supplement)
Error EA caused by non-concentricity between inner and outer spheres,Calculated by formula (A1): VII. Thermal insulation materials for buildings
R1-[1-()
EA=R/1
where r
eccentricity of the inner ball (m).
A2 Error caused by temperature drift of the inner ball
When the temperature of the inner ball drifts with time in steady state, the inner ball will absorb (or release) heat, resulting in heat flow measurement error. The measurement error ET caused by the absorption (or release) of heat by the inner ball is calculated by formula (A2): (dT)
×pi*c;V.
Inner ball heating rate (K/h);
-density of the inner ball material (kg/m3);P
-specific heat capacity of the inner ball material (J/(kg·K));V:---volume of the inner ball (m3).
When measuring low thermal conductivity materials with low temperature difference, this error is the largest. A3 Support tube heat transfer error
The heat transferred by the support tube that supports the inner ball to keep the inner and outer balls concentric will cause measurement errors. The smaller the thermal conductivity of the material being measured, the greater this error. When the two ends of the support tube have good thermal contact with the inner and outer balls, and the temperatures at the two ends of the support tube are the temperatures of the inner and outer balls respectively, the heat flow Q' transferred through the support tube is calculated by formula (A3): Q\-^\·F\.AT
Where Q' is the heat flow transferred by the support tube (W); AT-the temperature difference at both ends of the support tube (K). (A3)
Assuming that the heat transfer of the support tube does not affect the temperature field of the inner and outer balls, and ignoring the influence of the volume occupied by the support tube, the calculation formula for the thermal conductivity of the spherical device after considering the heat transfer of the support tube is: α =(QQ')2元AT-D·D2
D2 - D1
Q(D2 - Di)
>'FD2-Di
2元·AT·D·D2
Part I Test Methods for Major Building Materials Standard Formula (A4) The second item on the right side is the correction item caused by the heat transfer of the support tube. When the device is manufactured, this item is a constant. If the temperature at both ends of the support tube is not the same as the temperature of the inner and outer balls, the axial temperature gradient of the support tube will change with the temperature of the inner and outer balls, the ambient temperature and the structure of the instrument during measurement. The axial temperature gradient must be measured to make corrections. A4 Other errors
In addition to the above errors, the following errors should also be considered in the error analysis: α. Inner and outer ball size error;
b. Electric power measurement error;
c. Temperature measurement error (including thermocouple calibration error, installation error and measurement instrument error); d. Residual error after support tube heat transfer correction. This is caused by the support tube size measurement error and thermal conductivity error.
A5 Error synthesis
The sum of the absolute values of the above errors is the maximum error that may occur in the device, but the possibility of the effects of various errors accumulating in the same direction is very small. In general, if no error is particularly large, the comprehensive error of the device is 50%~75% of the maximum error.
Appendix B
Thermocouple error limits and types
(Supplement)
Thermocouple error limitsbZxz.net
Thermocouple types
New code
Temperature range
0～900
800~1 700
200 0
-200～0
-200～0
Note: 1) For thermocouples used below 0℃, this should be stated when ordering. Thermocouple type
New code
Old code
Platinum 30-Platinum 6 (double platinum thermocouple)
NiCr10-Constantan
NiCr10-Nickel Aluminum 3 (Nickel Silicon 5)
Iron-Constantan
Error limit-reference junction is 0℃
c (whichever is greater)
±1 or ±0.75%
±2.2 or ±0.75%
±1.7 or ±0.5%
±2.2 or ±0.75%
±1.5 or ±0.25%
±1 or ±1.5%
±1.7 or ±1%
±2.2 or ±2%
New code
c (the larger one)
±0.5 or ±0.4%
±1.1 or ±0.4%
±1 or ±0.4%
±1.1 or ±0.4%
±0.6 or ±0.1%
Table B2
Old code
Platinum 13-Platinum
Platinum 10-Platinum
Copper-Constantan
Additional instructions:
This standard was proposed by the State Building Materials Industry Bureau. This standard was drafted by Henan Building Materials Research and Design Institute. The main drafters of this standard were Cao Shengchuan and Chen Aizhu. VII. Thermal insulation materials for buildings
10. "Measurement of steady-state heat transfer characteristics of insulation layer - Circular tube method" GB10296-88 This standard adopts the international standard ISO/DIS8497-1986 "Thermal insulation - Determination of steady-state heat transfer characteristics of pipe insulation layer device".
Subject content and scope of application
This standard specifies the scope of application, terminology and measurement device, specimens, steps and result calculation of the circular tube method for measuring the steady-state heat transfer characteristics of insulation layer.
This standard is applicable to the determination of steady-state heat transfer characteristics of circular tube insulation layer (including longitudinal and transverse joints, moisture-proof layer and covering, etc.) that is usually higher than the ambient temperature.
2 Reference standards
GB4132 Terminology of thermal insulation materials
GB10294 Determination of steady-state thermal resistance and related properties of thermal insulation materials 3 Terms, definitions and symbols
3.1 The following term definitions in this standard are quoted from GB4132. 3.1.1 Heat flow Q (W).
3.1.2 Linear heat flux gL (W/m).
3.1.3 Heat flux g (W/m2).
3.2 The relevant symbols in this standard are as follows: 3.2.1 Measuring section length (axial direction) L (m). 3.2.2 Area of designated surface A (m2).
3.2.3 Pipe surface temperature To (K).
3.2.4 Insulation layer outer surface temperature T2 (K). 3.2.5 Outer diameter of round pipe do (m).
3.2.6 The outer diameter of the circular insulation layer is d2 (m). 3.3 The definitions of other terms in this standard are as follows: 3.3.1 Linear heat transfer rate TrL [W/(m·K)]
Guarded hot plate method
Under steady-state conditions, the linear heat flux is divided by the temperature difference between the pipe surface and the ambient gas. 9L
To- TaT. -T
-Ambient gas temperature (K).
Where T.
3.3.2 Linear thermal resistance Rl (mK/W)AT
Where Q' is the heat flux transferred by the support tube (W); AT is the temperature difference between the two ends of the support tube (K). (A3)
Assuming that the heat transfer of the support tube does not affect the temperature field of the inner and outer balls, and ignoring the influence of the volume occupied by the support tube, the calculation formula for the thermal conductivity of the spherical device after considering the heat transfer of the support tube is: α =(QQ')2 yuan AT-D·D2
D2 - D1
Q(D2 - Di)
>'FD2-Di
2 yuan·AT·D·D2
Part I Test Methods for Main Building Materials Standard Formula (A4) The second term on the right side is the correction term caused by the heat transfer of the support tube. When the device is manufactured, this term is a constant. If the temperature at both ends of the support tube is not the same as the temperature of the inner and outer balls, the axial temperature gradient of the support tube will change with the temperature of the inner and outer balls, the ambient temperature and the structure of the instrument during measurement. The axial temperature gradient must be measured to make corrections. A4 Other errors
In addition to the above errors, the following errors should also be considered in the error analysis: α. Inner and outer ball size errors;
b. Electric power measurement error;
C. Temperature measurement error (including thermocouple calibration error, installation error and measurement instrument error); d. Residual error after support tube heat transfer correction. This is caused by the support tube size measurement error and thermal conductivity error.
A5 Error synthesis
The sum of the absolute values of the above errors is the maximum error that may occur in the device, but the possibility of the effects of the errors accumulating in the same direction is very small. In general, if no error is particularly large, the comprehensive error of the device is 50%~75% of the maximum error.
Appendix B
Thermocouple error limits and types
(Supplement)
Thermocouple error limits
Thermocouple types
New code
Temperature range
0～900
800~1 700
200 0
-200～0
-200～0
Note: 1) For thermocouples used below 0℃, this should be stated when ordering. Thermocouple type
New code
Old code
Platinum 30-Platinum 6 (double platinum thermocouple)
NiCr10-Constantan
NiCr10-Nickel Aluminum 3 (Nickel Silicon 5)
Iron-Constantan
Error limit-reference junction is 0℃
c (whichever is greater)
±1 or ±0.75%
±2.2 or ±0.75%
±1.7 or ±0.5%
±2.2 or ±0.75%
±1.5 or ±0.25%
±1 or ±1.5%
±1.7 or ±1%
±2.2 or ±2%
New code
c (the larger one)
±0.5 or ±0.4%
±1.1 or ±0.4%
±1 or ±0.4%
±1.1 or ±0.4%
±0.6 or ±0.1%
Table B2
Old code
Platinum 13-Platinum
Platinum 10-Platinum
Copper-Constantan
Additional instructions:
This standard was proposed by the State Building Materials Industry Bureau. This standard was drafted by Henan Building Materials Research and Design Institute. The main drafters of this standard were Cao Shengchuan and Chen Aizhu. VII. Thermal insulation materials for buildings
10. "Measurement of steady-state heat transfer characteristics of insulation layer - Circular tube method" GB10296-88 This standard adopts the international standard ISO/DIS8497-1986 "Thermal insulation - Determination of steady-state heat transfer characteristics of pipe insulation layer device".
Subject content and scope of application
This standard specifies the scope of application, terminology and measurement device, specimens, steps and result calculation of the circular tube method for measuring the steady-state heat transfer characteristics of insulation layer.
This standard is applicable to the determination of steady-state heat transfer characteristics of circular tube insulation layer (including longitudinal and transverse joints, moisture-proof layer and covering, etc.) that is usually higher than the ambient temperature.
2 Reference standards
GB4132 Terminology of thermal insulation materials
GB10294 Determination of steady-state thermal resistance and related properties of thermal insulation materials 3 Terms, definitions and symbols
3.1 The following term definitions in this standard are quoted from GB4132. 3.1.1 Heat flow Q (W).
3.1.2 Linear heat flux gL (W/m).
3.1.3 Heat flux g (W/m2).
3.2 The relevant symbols in this standard are as follows: 3.2.1 Measuring section length (axial direction) L (m). 3.2.2 Area of designated surface A (m2).
3.2.3 Pipe surface temperature To (K).
3.2.4 Insulation layer outer surface temperature T2 (K). 3.2.5 Outer diameter of round pipe do (m).
3.2.6 The outer diameter of the circular insulation layer is d2 (m). 3.3 The definitions of other terms in this standard are as follows: 3.3.1 Linear heat transfer rate TrL [W/(m·K)]
Guarded hot plate method
Under steady-state conditions, the linear heat flux is divided by the temperature difference between the pipe surface and the ambient gas. 9L
To- TaT. -T
-Ambient gas temperature (K).
Where T.
3.3.2 Linear thermal resistance Rl (mK/W)AT
Where Q' is the heat flux transferred by the support tube (W); AT is the temperature difference between the two ends of the support tube (K). (A3)
Assuming that the heat transfer of the support tube does not affect the temperature field of the inner and outer balls, and ignoring the influence of the volume occupied by the support tube, the calculation formula for the thermal conductivity of the spherical device after considering the heat transfer of the support tube is: α =(QQ')2 yuan AT-D·D2
D2 - D1
Q(D2 - Di)
>'FD2-Di
2 yuan·AT·D·D2
Part I Test Methods for Main Building Materials Standard Formula (A4) The second term on the right side is the correction term caused by the heat transfer of the support tube. When the device is manufactured, this term is a constant. If the temperature at both ends of the support tube is not the same as the temperature of the inner and outer balls, the axial temperature gradient of the support tube will change with the temperature of the inner and outer balls, the ambient temperature and the structure of the instrument during measurement. The axial temperature gradient must be measured to make corrections. A4 Other errors
In addition to the above errors, the following errors should also be considered in the error analysis: α. Inner and outer ball size errors;
b. Electric power measurement error;
C. Temperature measurement error (including thermocouple calibration error, installation error and measurement instrument error); d. Residual error after support tube heat transfer correction. This is caused by the support tube size measurement error and thermal conductivity error.
A5 Error synthesis
The sum of the absolute values of the above errors is the maximum error that may occur in the device, but the possibility of the effects of the errors accumulating in the same direction is very small. In general, if no error is particularly large, the comprehensive error of the device is 50%~75% of the maximum error.
Appendix B
Thermocouple error limits and types
(Supplement)
Thermocouple error limits
Thermocouple types
New code
Temperature range
0～900
800~1 700
200 0
-200～0
-200～0
Note: 1) For thermocouples used below 0℃, this should be stated when ordering. Thermocouple type
New code
Old code
Platinum 30-Platinum 6 (double platinum thermocouple)
NiCr10-Constantan
NiCr10-Nickel Aluminum 3 (Nickel Silicon 5)
Iron-Constantan
Error limit-reference junction is 0℃
c (whichever is greater)
±1 or ±0.75%
±2.2 or ±0.75%
±1.7 or ±0.5%
±2.2 or ±0.75%
±1.5 or ±0.25%
±1 or ±1.5%
±1.7 or ±1%
±2.2 or ±2%
New code
c (the larger one)
±0.5 or ±0.4%
±1.1 or ±0.4%
±1 or ±0.4%
±1.1 or ±0.4%
±0.6 or ±0.1%
Table B2
Old code
Platinum 13-Platinum
Platinum 10-Platinum
Copper-Constantan
Additional instructions:
This standard was proposed by the State Building Materials Industry Bureau. This standard was drafted by Henan Building Materials Research and Design Institute. The main drafters of this standard were Cao Shengchuan and Chen Aizhu. VII. Thermal insulation materials for buildings
10. "Measurement of steady-state heat transfer characteristics of insulation layer - Circular tube method" GB10296-88 This standard adopts the international standard ISO/DIS8497-1986 "Thermal insulation - Determination of steady-state heat transfer characteristics of pipe insulation layer device".
Subject content and scope of application
This standard specifies the scope of application, terminology and measurement device, specimens, steps and result calculation of the circular tube method for measuring the steady-state heat transfer characteristics of insulation layer.
This standard is applicable to the determination of steady-state heat transfer characteristics of circular tube insulation layer (including longitudinal and transverse joints, moisture-proof layer and covering, etc.) that is usually higher than the ambient temperature.
2 Reference standards
GB4132 Terminology of thermal insulation materials
GB10294 Determination of steady-state thermal resistance and related properties of thermal insulation materials 3 Terms, definitions and symbols
3.1 The following term definitions in this standard are quoted from GB4132. 3.1.1 Heat flow Q (W).
3.1.2 Linear heat flux gL (W/m).
3.1.3 Heat flux g (W/m2).
3.2 The relevant symbols in this standard are as follows: 3.2.1 Measuring section length (axial direction) L (m). 3.2.2 Area of designated surface A (m2).
3.2.3 Pipe surface temperature To (K).
3.2.4 Insulation layer outer surface temperature T2 (K). 3.2.5 Outer diameter of round pipe do (m).
3.2.6 The outer diameter of the circular insulation layer is d2 (m). 3.3 The definitions of other terms in this standard are as follows: 3.3.1 Linear heat transfer rate TrL [W/(m·K)]
Guarded hot plate method
Under steady-state conditions, the linear heat flux is divided by the temperature difference between the pipe surface and the ambient gas. 9L
To- TaT. -T
-Ambient gas temperature (K).
Where T.
3.3.2 Linear thermal resistance Rl (mK/W)"Measurement of Steady-State Heat Transfer Characteristics of Insulation Layer - Circular Tube Method" GB10296-88 This standard adopts the international standard ISO/DIS8497-1986 "Thermal Insulation - Device for Determining Steady-State Heat Transfer Characteristics of Pipe Insulation Layer".
Subject Content and Scope of Application
This standard specifies the scope of application, terminology and measurement device, specimen, steps and result calculation of the circular tube method for determining the steady-state heat transfer characteristics of insulation layer.
This standard is applicable to the determination of steady-state heat transfer characteristics of circular tube insulation layer (including longitudinal and transverse joints, moisture-proof layer and covering, etc.) that is usually higher than the ambient temperature.
2 Reference Standards
GB4132 Terminology of Insulation Materials
GB10294 Determination of Steady-State Thermal Resistance and Related Characteristics of Insulation Materials 3 Terms, Definitions and Symbols
3.1 The following term definitions in this standard are quoted from GB4132. 3.1.1 Heat flow Q (W).
3.1.2 Linear heat flux gL (W/m).
3.1.3 Heat flux g (W/m2).
3.2 The relevant symbols in this standard are as follows: 3.2.1 Measuring section length (axial direction) L (m). 3.2.2 Area of designated surface A (m2).
3.2.3 Pipe surface temperature To (K).
3.2.4 Insulation layer outer surface temperature T2 (K). 3.2.5 Outer diameter of circular pipe do (m).
3.2.6 Outer diameter of circular insulation layer d2 (m). 3.3 The definitions of other terms in this standard are as follows: 3.3.1 Linear heat transfer rate TrL [W/(m·K)]
Guarded hot plate method
Under steady-state conditions, the linear heat flux is divided by the temperature difference between the pipe surface and the ambient gas. 9L
To- TaT. -T
-Ambient gas temperature (K).
Where T.
3.3.2 Line thermal resistance Rl (mK/W)"Measurement of Steady-State Heat Transfer Characteristics of Insulation Layer - Circular Tube Method" GB10296-88 This standard adopts the international standard ISO/DIS8497-1986 "Thermal Insulation - Device for Determining Steady-State Heat Transfer Characteristics of Pipe Insulation Layer".
Subject Content and Scope of Application
This standard specifies the scope of application, terminology and measurement device, specimen, steps and result calculation of the circular tube method for determining the steady-state heat transfer characteristics of insulation layer.
This standard is applicable to the determination of steady-state heat transfer characteristics of circular tube insulation layer (including longitudinal and transverse joints, moisture-proof layer and covering, etc.) that is usually higher than the ambient temperature.
2 Reference Standards
GB4132 Terminology of Insulation Materials
GB10294 Determination of Steady-State Thermal Resistance and Related Characteristics of Insulation Materials 3 Terms, Definitions and Symbols
3.1 The following term definitions in this standard are quoted from GB4132. 3.1.1 Heat flow Q (W).
3.1.2 Linear heat flux gL (W/m).
3.1.3 Heat flux g (W/m2).
3.2 The relevant symbols in this standard are as follows: 3.2.1 Measuring section length (axial direction) L (m). 3.2.2 Area of designated surface A (m2).
3.2.3 Pipe surface temperature To (K).
3.2.4 Insulation layer outer surface temperature T2 (K). 3.2.5 Outer diameter of circular pipe do (m).
3.2.6 Outer diameter of circular insulation layer d2 (m). 3.3 The definitions of other terms in this standard are as follows: 3.3.1 Linear heat transfer rate TrL [W/(m·K)]
Guarded hot plate method
Under steady-state conditions, the linear heat flux is divided by the temperature difference between the pipe surface and the ambient gas. 9L
To- TaT. -T
-Ambient gas temperature (K).
Where T.
3.3.2 Line thermal resistance Rl (mK/W)
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