GB/T 18443.6-2010 PDF in English
GB/T 18443.6-2010 (GB/T18443.6-2010, GBT 18443.6-2010, GBT18443.6-2010)
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Testing method of performance for vacuum insulation cryogenic equipment -- Part 6: Heat-leak rate measurement
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Standards related to (historical): GB/T 18443.6-2010
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GB/T 18443.6-2010: PDF in English (GBT 18443.6-2010) GB/T 18443.6-2010
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020
J 74
Testing method of performance for vacuum insulation
cryogenic equipment - Part 6.Heat-leak rate measurement
ISSUED ON. SEPTEMBER 26, 2010
IMPLEMENTED ON. FEBRUARY 01, 2011
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative references... 4
3 Terms and definitions... 5
4 Test principles and methods... 5
5 Test devices, equipment and instruments... 6
6 Test conditions and test preparation... 7
7 Test steps... 7
8 Data processing... 8
9 Test record and test report... 13
Annex A (informative) Heat-leak rate test record... 14
Annex B (informative) Air physical property data under standard atmospheric pressure
(101.325kPa)... 15
Annex C (informative) Heat-leak rate test report... 18
Testing method of performance for vacuum insulation
cryogenic equipment - Part 6.Heat-leak rate measurement
1 Scope
This Part of GB/T 18443 specifies test principles and methods, test devices, equipment
and instruments, test conditions and test preparation, test procedures, data processing
and test record and test report for the heat-leak rate measurement of vacuum insulation
cryogenic equipment.
This part applies to the heat-leak rate measurement of vacuum insulation cryogenic
pressure vessels, vacuum insulation cryogenic welded gas cylinders, vacuum insulation
pipes and their pipe fittings, except the liquid hydrogen storing and transporting
equipment. Other equipment can refer to this document for the implementation.
The flowmeter measurement method is suitable for the heat-leak rate measurement of
vacuum insulation cryogenic pressure vessels, vacuum insulation cryogenic welding
gas cylinders and other vacuum insulation cryogenic equipment. The surface
temperature measurement method is suitable for the heat-leak rate measurement of
vacuum insulation pipes and their fittings.
2 Normative references
The provisions in following documents become the provisions of this Part of GB/T
18443 through reference in this Part. For dated references, the subsequent amendments
(excluding corrigendum) or revisions do not apply to this Part, however, parties who
reach an agreement based on this Part are encouraged to study if the latest versions of
these documents are applicable. For undated references, the latest edition of the
referenced document applies.
GB/T 18443.1-2010, Testing method of performance for vacuum insulation
cryogenic equipment - Part 1.Basic requirements
GB/T 18443.2, Testing method of performance for vacuum insulation cryogenic
equipment - Part 2.Vacuum degree measurement
GB/T 18443.3, Testing method of performance for vacuum insulation cryogenic
equipment - Part 3.Leak rate measurement
GB/T 18443.4, Testing method of performance for vacuum insulation cryogenic
equipment - Part 4.Leak-outgassing rate measurement
GB/T 18443.5-2010, Testing method of performance for vacuum insulation
cryogenic equipment - Part 5.Static evaporation rate measurement
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T
18443.1~GB/T 18443.5 as well as the followings apply.
3.1 heat-leak rate
The heat transferred from the surrounding environment to the storage medium of the
vacuum insulation cryogenic equipment per unit time, in watts (W).
3.2 test heat-leak rate
After the vacuum insulation cryogenic equipment is fully cooled and reaches thermal
equilibrium, the heat transferred from the surrounding environment to the storage
medium of the vacuum adiabatic cryogenic equipment per unit time, in watts (W).
3.3 heat-leak rate of standard ambient condition
The test heat-leak rate is converted to the value of the heat-leak rate under the standard
environmental state, in watts (W).
4 Test principles and methods
4.1 Flowmeter measurement method
The test principle, method and device conform to the provisions of 4.2.1 and 4.2.2 in
GB/T 18443.5-2010.
4.2 Surface temperature measurement method
4.2.1 Test principle and method
Measure the outer surface temperature of the vacuum insulation pipe and the
corresponding ambient temperature. Calculate the heat-leak rate into the vacuum
insulation pipe according to the natural convection in the large space. Calculate the heat
conduction heat-leak rate of the joint according to the difference between the measured
temperature of the air side of the joint and the temperature of the liquid. Or establish
the finite element heat transfer model of the joint to solve the heat-leak rate of the joint.
The schematic diagram of the test device is shown in Figure 1.
b) The rated flow rate of the flowmeter shall be compatible with the gas flow rate
evaporated by the tested vacuum insulation cryogenic pipe;
c) There shall be ambient temperature, ambient atmospheric pressure and flowmeter
inlet temperature and pressure measurement devices.
6 Test conditions and test preparation
6.1 Test conditions and test preparation shall comply with the provisions of GB/T
18443.1.
6.2 When using the surface temperature method, the measurement shall be carried out
in a room protected from light, natural convection and no wind.
6.3 The effective length of the test vacuum insulation pipe shall not be less than 5m. No
less than 6 temperature measurement points are evenly distributed at the bottom of the
surface of the outer pipe with a length of 3m in the middle.
6.4 The inner volume of the auxiliary test section shall be greater than twice the inner
volume of the test vacuum insulation pipe. The height of the auxiliary test section shall
be less than 1.5m.
7 Test steps
7.1 Flowmeter measurement method
The test procedures, test process and data record shall comply with the provisions in
7.1 of GB/T 18443.5.
7.2 Surface temperature measurement method
7.2.1 Liquid nitrogen is generally used as the test medium. The actual delivered
cryogenic liquid can be used as the test medium.
7.2.2 Open valve 10.Use the cryogenic container 11 to continuously deliver cryogenic
liquid to the test vacuum insulation pipe and its pipe fittings until they are full. When
the liquid level in the auxiliary test section drops to half, it shall be refilled with liquid.
Ensure that the test vacuum insulation pipe is filled with test medium liquid.
7.2.3 The data can be recorded only after the vacuum insulation pipe and its fittings
have been continuously conveying cryogenic liquid for 24h.
7.2.4 The data recording shall be based on the time interval of not more than 10min,
collection surface and ambient temperature, until the relative error of the collected data
within 1h is less than ± 5%.
Where,
Q0 - Total heat-leak rate of the joint pair, in watts (W)
D1 - The outer diameter of the outer pipe of the male joint, in meters (m);
D2 - The inner diameter of the outer pipe of the male joint, in meters (m);
δ1 - The outer pipe wall thickness of the male joint, in meters (m);
δ2 - The inner pipe wall thickness of the female joint, in meters (m);
Twj1 - The average temperature of the outer surface of the male joint in contact with
the environment, in Kelvin (K);
Twj2 - The average temperature of the outer surface of the female joint in contact
with the environment, in Kelvin (K);
T2 - The saturation temperature of the cryogenic liquid corresponding to the average
pressure in the test piece during the test, in Kelvin (K);
λ1 - The average thermal conductivity of the outer pipe material of the male joint in
the temperature zone from Twj1 to T2, in watts per meter Kelvin (W/m·K);
λ2 - The average thermal conductivity of the inner pipe material of the female joint
in the temperature zone from Twj2 to T2, in watts per meter Kelvin (W/m·K);
L1 - The length of the outer pipe of the male joint, in meters (m);
L2 - The length of the inner pipe of the female connector, in meters (m).
b) When calculating the heat-leak rate of other joint pairs in the pipeline, consider
the heat conduction structure of the actual size. The temperature difference is the
difference between the measured surface temperature and the saturated liquid
temperature. For complex structures, it shall use finite element thermal analysis
and calculation.
8.2 Calculation of heat-leak rate Q20 of standard state (standard ambient condition)
8.2.1 The heat-leak rate Q20 of high vacuum multi-layer insulation of the standard state
shall be calculated according to formula (9).
Where,
Q20 - The heat-leak rate of standard state, in watts (W);
Q0 - The total heat-leak rate of the joint pair, in watts (W);
Ts - The cryogenic liquid saturation temperature under standard atmospheric pressure
(101.325kPa), in Kelvin (K);
T1 - The average ambient temperature during the test, in Kelvin (K);
T2 - The saturation temperature of the cryogenic liquid corresponding to the average
pressure in the test piece during the test, in Kelvin (K).
8.2.2 The powder or fiber vacuum insulation heat-leak rate Q20 of the standard state
shall be calculated according to formula (10).
Where,
Q20 - The heat-leak rate of the standard state, in watts (W);
Q0 - The total heat-leak rate of the joint pair, in watts (W);
Ts - The cryogenic liquid saturation temperature under standard atmospheric pressure
(101.325kPa), in Kelvin (K);
T1 - The average ambient temperature during the test, in Kelvin (K);
T2 - The saturation temperature of the cryogenic liquid corresponding to the average
pressure in the test piece during the test, in Kelvin (K).
8.2.3 The high vacuum insulation heat-leak rate Q20 of the standard state shall be
calculated according to formula (11).
Where,
Q20 - The heat-leak rate of the standard state, in watts (W);
Q0 - The total heat-leak rate of the joint pair, in watts (W);
Ts - The cryogenic liquid saturation temperature under standard atmospheric pressure
(101.325kPa), in Kelvin (K);
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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