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ASTM E341-08(2020)

(Practice)

Standard Practice for Measuring Plasma Arc Gas Enthalpy by Energy Balance

Standard Practice for Measuring Plasma Arc Gas Enthalpy by Energy Balance

SIGNIFICANCE AND USE
3.1 The purpose of this practice is to measure the total or stagnation gas enthalpy of a plasma-arc gas stream in which nonreactive gases are heated by passage through an electrical discharge device during calibration tests of the system.  
3.2 The plasma arc represents one heat source for determining the performance of high temperature materials under simulated hyperthermal conditions. As such the total or stagnation enthalpy is one of the important parameters for correlating the behavior of ablation materials.  
3.3 The most direct method for obtaining a measure of total enthalpy, and one which can be performed simultaneously with each material test, if desired, is to perform an energy balance on the arc chamber. In addition, in making the energy balance, accurate measurements are needed since the efficiencies of some plasma generators are low (as low as 15 to 20 % or less in which case the enthalpy depends upon the difference of two quantities of nearly equal magnitude). Therefore, the accuracy of the measurements of the primary variables must be high, all energy losses must be correctly taken into account, and steady-state conditions must exist both in plasma performance and fluid flow.  
3.4 In particular it is noted that total enthalpy as determined by the energy balance technique is most useful if the plasma generator design minimizes coring effects. If nonuniformity exists the enthalpy determined by energy balance gives only the average for the entire plasma stream, whereas the local enthalpy experienced by a model in the core of the stream may be much higher. More precise methods are needed to measure local variations in total enthalpy.
SCOPE
1.1 This practice covers the measurement of total gas enthalpy of an electric-arc-heated gas stream by means of an overall system energy balance. This is sometimes referred to as a bulk enthalpy and represents an average energy content of the test stream which may differ from local values in the test stream.  
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

Status
Published
Publication Date
31-Oct-2020
ICS
17.200.10 - Heat. Calorimetry
Technical Committee
E21 - Space Simulation and Applications of Space Technology
Drafting Committee
E21.08 - Thermal Protection
Current Stage
Ref Project

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ASTM E341-08(2020) - Standard Practice for Measuring Plasma Arc Gas Enthalpy by Energy BalanceASTM E341-08(2020) - Standard Practice for Measuring Plasma Arc Gas Enthalpy by Energy Balance
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ASTM E341-08(2020) - Standard Practice for Measuring Plasma Arc Gas Enthalpy by Energy Balance
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E341 − 08 (Reapproved 2020)
Standard Practice for
1
Measuring Plasma Arc Gas Enthalpy by Energy Balance
This standard is issued under the fixed designation E341; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope higher temperature. Across the arc, electrical energy is dissi-
pated by virtue of the resistance and current in the arc itself.A
1.1 This practice covers the measurement of total gas
heat balance of the system requires that the energy gained by
enthalpy of an electric-arc-heated gas stream by means of an
thegasmustbedefinedbythedifferencebetweentheincoming
overallsystemenergybalance.Thisissometimesreferredtoas
energy (electrical input) and total coolant and external losses.
abulkenthalpyandrepresentsanaverageenergycontentofthe
This is a direct application of the First Law of Thermodynam-
test stream which may differ from local values in the test
ics and, for the particular control volume cited here, can be
stream.
written as follows:
1.2 This standard does not purport to address all of the
EnergyIn 2 EnergyOut 5 EnergytoGas (1)
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
n p
priate safety, health, and environmental practices and deter- ¯
EI 2 Q 2 W C ∆T 2∆T 2 M H
~ !
CR ( p 0 1 H O ( j j
H O 2 i
2 i
i51 j51
mine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accor-
5W H 2 H
~ !
g g in
dance with internationally recognized principles on standard-
where:
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
C = water, specific heat,
p
mendations issued by the World Trade Organization Technical E = plasma arc voltage,
Barriers to Trade (TBT) Committee. H = exhaust gas enthalpy,
g
H = inlet gas enthalpy,
in
H = heat of vaporization corresponding to the material
2. Summary of Test Method
j
M ,
j
2.1 A measure of the total or stagnation gas enthalpy of
I = plasma arc current,
plasma-arc heated gases (nonreacting) is based upon the
M = mass loss rate of electrode insulator, interior metal
j
following measurements:
surface, etc.
2.1.1 Energy input to the plasma arc,
Q = energy convected and radiated from external sur-
CR
2.1.2 Energy losses to the plasma arc hardware and cooling
face of plasma generator,
water, and
∆T = T − T =water temperature rise during plasma
0 0 0
H2O 2 1
2.1.3 Gas mass flow.
arc operation,
2.2 The gas enthalpy is determined numerically by dividing ∆T = T −T =water temperature rise before plasma arc
1 2 1
H2O
operation,
the gas mass flow into the net power input to the plasma arc
T = water exhaust temperature during plasma arc
(power to plasma arc minus the energy losses).
0
2
operation,
2.3 Thetechniqueforperformingtheoverallenergybalance
T = inlet water temperature during plasma arc
0
1
is illustrated schematically in Fig. 1. The control volume for
operation,
theenergybalancecanberepresentedbytheentireenvelopeof
T = water exhaust temperature before plasma arc
2
this drawing. Gas enters at an initial temperature, or enthalpy,
operation,
andemergesatahigherenthalpy.Waterorothercoolantenters
T = inlet water temperature before plasma arc
1
the control volume at an initial temperature and emerges at a
operation,
W = gas flow rate,
g
W O = mass flow rate of coolant water, and
H
2
1
This practice is under the jurisdiction of ASTM Committee E21 on Space
¯
= averageoftheproductofvoltage, E,andcurrent, I.
EI
Simulation andApplications of SpaceTechnology and is the direct responsibility of
Subcommittee E21.08 on Thermal Protection.
2.4 AnexaminationofEq1showsthat,inordertoobtainan
Current edition approved Nov. 1, 2020. Published December 2020. Originally
evaluation of the energy content of the plasma for a specified
approvedin1968.Lastpreviouseditionapprovedin2015asE341–08(2015).DOI:
10.1520/E0341-08R20. setofoperatingconditions,measurementsmustbemadeofthe
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E341 − 08 (2020)
FIG. 1 Schematic Energy Balance Method for Determining Gas
Enthalpy
voltage and current, the mass-flow rate and temperature rise of nation enthalpy is one of the important parameters for corre-
the coolant, the mass-flow rate and inlet ambient temperature lating the behavior of ablat
...

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5.1 The purpose of this test method is to measure extremely high heat-transfer rates to a body immersed in either a static environment or in a high velocity fluid stream. This is usually accomplished while preserving the structural integrity of the measurement device for multiple exposures during the measurement period. Heat-transfer rates ranging up to 2.84 × 102 MW/m2 (2.5 × 104 Btu/ft2-sec) (7) have been measured using null-point calorimeters. Use of copper null-point calorimeters provides a measuring system with good response time and maximum run time to sensor burnout (or ablation). Null-point calorimeters are normally made with sensor body diameters of 2.36 mm (0.093 in.) press-fitted into the nose of an axisymmetric model.  
5.2 Sources of error involving the null-point calorimeter in high heat-flux measurement applications are extensively discussed in Refs (3-7). In particular, it has been shown both analytically and experimentally that the thickness of the copper above the null-point cavity is critical. If the thickness is too great, the time response of the instrument will not be fast enough to pick up important flow characteristics. On the other hand, if the thickness is too small, the null-point calorimeter will indicate significantly larger (and time dependent) values than the input or incident heat flux. Therefore, all null-point calorimeters should be experimentally checked for proper time response and calibration before they are used. Although a calibration apparatus is not very difficult or expensive to fabricate, there is only one known system presently in existence (6 and 7). The design of null-point calorimeters can be accomplished from the data in this documentation. However, fabrication of these sensors is a difficult task. Since there is not presently a significant market for null-point calorimeters, commercial sources of these sensors are few. Fabrication details are generally regarded as proprietary information. Some users have developed me...
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1.1 This test method covers the measurement of the heat-transfer rate or the heat flux to the surface of a solid body (test sample) using the measured transient temperature rise of a thermocouple located at the null point of a calorimeter that is installed in the body and is configured to simulate a semi-infinite solid. By definition the null point is a unique position on the axial centerline of a disturbed body which experiences the same transient temperature history as that on the surface of a solid body in the absence of the physical disturbance (hole) for the same heat-flux input.  
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1.5 ISO standards 11357–2 is equivalent to this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM
ASTM E2603-15(2023)(Practice)
Standard Practice for Calibration of Fixed-Cell Differential Scanning Calorimeters

SIGNIFICANCE AND USE
5.1 Fixed-cell differential scanning calorimeters are used to determine the transition temperatures and energetics of materials in solution. For this information to be accepted with confidence in an absolute sense, temperature and heat calibration of the apparatus or comparison of the resulting data to that of known standard materials is required.  
5.2 This practice is useful in calibrating the temperature and heat flow axes of fixed-cell differential scanning calorimeters.
SCOPE
1.1 This practice covers the calibration of fixed-cell differential scanning calorimeters over the temperature range from –10 °C to +120 °C.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM
ASTM C1702-23(Test Method)
Standard Test Method for Measurement of Heat of Hydration of Hydraulic Cementitious Materials Using Isothermal Conduction Calorimetry

SIGNIFICANCE AND USE
5.1 This method is suitable for determining the total heat of hydration of hydraulic cement at constant temperature at ages up to 7 days to confirm specification compliance.  
5.2 This method compliments Practice C1679 by providing details of calorimeter equipment, calibration, and operation. Practice C1679 emphasizes interpretation significant events in cement hydration by analysis of time dependent patterns of heat flow, but does not provide the level of detail necessary to give precision test results at specific test ages required for specification compliance.
SCOPE
1.1 This test method specifies the apparatus and procedure for determining total heat of hydration of hydraulic cementitious materials at test ages up to 7 days by isothermal conduction calorimetry.  
1.2 This test method also outputs data on rate of heat of hydration versus time that is useful for other analytical purposes, as covered in Practice C1679.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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  • Standard
    8 pages
    English language
    sale 15% off