1、 SURFACE VEHICLE STANDARD Multi-Dimensional Thermal Properties of Insulated Heat Shield Material Systems SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and it
2、s applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written commen
3、ts and suggestions. Copyright 2003 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SA
4、E. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org ISSUED DEC2003 Issued 2003-12 J2609 1. Scope This test method measures the system material properties of an insulated for
5、med heat shield under in-vehicle conditions. While the material properties of the individual components can often be determined via existing test methods, the system properties of the entire composite is typically much harder to ascertain (especially for multi-layer shields). System material propert
6、ies include thermal conductivity in the lateral or in-plane (x) direction, thermal conductivity through the thickness or perpendicular (y), surface emissivity on the top and bottom sides of the shield and specific heat of the shield material. 1.1 All properties are determined for the entire shieldin
7、g material specimen as a composite of the entire structure. Properties are determined using a testing apparatus that allows for two-dimensional heat flow through the specimen. Due to this, the material property results from this test method may not agree with one-dimensional heat flow type testing m
8、ethods, but is representative of most heat shield materials performance tested with a centralized heat source. Therefore, material property results from this test method may be more suited for multi-dimensional analytical studies. 1.2 This standard sets forth the general guidelines to construct and
9、operate the testing apparatus to acquire a satisfactory set of test data. Designs conforming to this standard are included and must not be deviated from for sensitivity reasons that will be discussed in more detail later. Test parameters that cannot be deviated from include, but are not limited to;
10、specimen size, distance between the source and the specimen, source diameter and environmental conditions around the apparatus. 1.3 This method ultimately determines the shield material properties by using the test data along with an analytical scheme, see Section 8.1. 1.4 This test method will eval
11、uate both isotropic and anisotropic insulated shielding materials. This may also include multi-layer shielding structures which include embossed/corrugated solids, porous, fibrous, granulated and coated materials. SAE J2609 Issued DEC2003 - 2 - 1.5 Limitations This test method does have limitations
12、in the type of insulated shielding materials that can be evaluated. However, many of the limitations apply to materials that would not typically be suitable in a heat shielding function or the properties can be derived by simpler one-dimensional hot plate methods (SAE J1361, ASTM C 177). Limitations
13、 include: a) Materials where the radiant transmissivity through the material cannot be assumed as zero. Materials of this type are classified as translucent or transparent. b) Materials that do not have an insulating characteristic in at least one axis; (i.e., single wall stamped metal shielding). T
14、his includes shielding materials where lateral thermal conductivity (x) and thermal conductivity through the thickness (y) are the same and considered high (in the order of 25 W/m-C) when compared to metallic materials. These types of single sheet metallic shields are not included in the standard be
15、cause the properties of these materials are typically well known and do not require a procedure to determine them. c) Materials where the lateral thermal conductivity (x) is less than the thermal conductivity through the thickness (y). d) Testing exposes the shielding material to temperatures up to
16、250oC. Materials with limits below this level should not use this method. 1.6 Safety This method involves a test apparatus that exposes the operator to very high temperatures. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibil
17、ity of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.7 The attached Appendix A provides a detailed discussion of the analytical technique used in calculating the insulated shielding material pr
18、operties from the test data. The Appendix A also presents the theoretical sensitivity study of the analytical method. 1.8 This test method requires two specific pieces of test instrumentation. A portable emissometer as outlined in ASTM C1371 and a radiosity meter or infrared camera with the ability
19、to set the emissivity to 1.0. SAE J2609 Issued DEC2003 - 3 - 2. References 2.1 Related Publications The following publications are for informational purposes only. The ShieldProp and ShieldTherm programs, available free from ThermoAnalytics at http:/ were written specifically to solve the equations
20、for this standard and give examples. 2.1.1 SAE PUBLICATIONS Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J1361 Hot Plate Method for Evaluating Heat Resistance and Thermal Insulation Properties of Materials 2.1.2 ASTM PUBLICATIONS Available from ASTM, 100 Barr Harbor Dri
21、ve, West Conshohocken, PA 19428-2959. ASTM C177 Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot Plate Apparatus ASTM C1371 Standard Test Method for Determination of Emittance of Materials Near Room Temperature Using Portabl
22、e Emissometers 3. Summary This method describes a testing procedure and equipment, coupled with a computer analyses to directly measure or calculate the base material properties of an insulated shielding specimen. These material properties include thermal conductivity in the lateral or in-plane (x)
23、direction, thermal conductivity through the thickness (y), surface emissivity on the top and bottom sides of the shield, density, and specific heat of the shield material. 3.1 Figure 1 is a slice through the thickness of a shield to illustrate a typical multi-dimensional heat flow through an insulat
24、ed shielding specimen with a centralized heat source. This arrangement is very typical of actual in-vehicle usage and is the basis for this test method. 3.2 This test method is designed to induce a multi-dimensional heat flow pattern into the insulated shield test specimen. After collecting temperat
25、ure data on both the shielding material and ambient with a predetermined arrangement, the following composite shield material properties can be calculated: thermal conductivity in the lateral or in-plane (x) direction, thermal conductivity through the thickness (y), and specific heat of the shield.
26、Surface emissivity on the top and bottom sides of the shield are obtained through the use of ASTM Standard C 1371 and not analytically calculated as part of this test method, although, it is a required piece of data for the analytical software program. Also, heat source radiosity is a required input
27、 to the analytical software program. Both surface emissivity of the shield, heat source radiosity and floor radiosity are obtained through the use of additional equipment as outlined in Section 4. Since specific heat is one of the properties the test method calculates, the test procedure and the dat
28、a collected will be done in a transient mode. SAE J2609 Issued DEC2003 - 4 - FIGURE 1MULTI-DIMENSIONAL HEAT FLOW THROUGH SHIELDING MATERIAL WITH CENTRAL HEAT SOURCE 3.3 Figure 2 illustrates the main components of the test set-up. Two shield specimen sizes are required to be tested independently duri
29、ng this method, 22.5 cm x 45 cm and 45 cm square. Both are required to satisfy the sensitivity requirements of the analytical calculation. The insulated shield test specimen is thermocoupled on the top and the bottom, identically, in the arrangement displayed in Figures 3 and 4. It is important that
30、 the thermocouples be completely shielded from direct radiant energy from the heat source. Also, an ambient thermocouple, similarly shielded, is set to measure the ambient air temperature in the test area that would represent T. The ambient thermocouple is intended to measure the average temperature
31、 of the air at a distance sufficiently outside the convective boundary layer of the shield specimen. A cylindrical heat source of 5.08 cm in diameter is positioned 25.4 mm above and centered on the specimen. The heat source is held at a constant, average temperature of 400oC (as measured across the
32、length of the test specimen) during the entire transient test. As soon as the heat source is at steady state, the insulated shield specimen is moved quickly into position and the data collection is started. 3.4 Data collection is started and continued until steady state is reached on the insulated s
33、hield test specimen. Data sampling rates should be a least one per minute. Data should continue to be taken, after the specimen has reached steady state, for at least ten minutes. Data is saved to a predetermined comma delimited (.csv) format, Table 1. SAE J2609 Issued DEC2003 - 5 - FIGURE 2MAIN COM
34、PONENTS OF EXPERIMENTAL SETUP FIGURE 3THERMOCOUPLE ARRANGEMENT ON 45 cm SAMPLE SAE J2609 Issued DEC2003 - 6 - TABLE 1EXPERIMENTAL RESULTS, FORMAT OF THE .CSV DATA FILE Column # Test Data 1 Time (seconds) 2 Temp Heat Source (C) 3 Temp Room Ambient (C) 4 Temp Top of Specimen (center, #1 position) 5 Te
35、mp Top of Specimen (#2 position) 6 Temp Top of Specimen (#3 position) 7 Temp Top of Specimen (#4 position) 8 Temp Top of Specimen (#5 position) 9 Temp Bottom of Specimen (center, #1 position) 10 Temp Bottom of Specimen (#2 position) 11 Temp Bottom of Specimen (#3 position) 12 Temp Bottom of Specimen
36、 (#4 position) 13 Temp Bottom of Specimen (#5 position) FIGURE 4THERMOCOUPLE ARRANGEMENT ON 22.5 cm SAMPLE SAE J2609 Issued DEC2003 - 7 - 3.5 Both the 22.5 cm and 45 cm width specimen sizes are tested using the same procedure and the data saved to separate .csv files. 3.6 The data is read into an av
37、ailable analytical software program that calculates the base material properties of the insulated shield material. 4. Equipment 4.1 Heated pipe The radiant heat source for this test is a heated cylindrical pipe that has a 5.08 0.013 cm (2.0 0.005 inch) outer diameter. The pipe should be made from 31
38、0 stainless steel for durability and because the analytical program calculates pipe growth due to heating, which will change the distance between the heat source and the specimen. The pipe may be also made from 316 stainless steel which has equivalent thermal expansion as 310 but the durability may
39、not be as good. It must be capable of continuous operation at 400oC without drooping or serious degradation. Discoloration of the heat source is acceptable as long as it is uniform across the surface of the pipe. The pipe must be at least 61 cm (24 inches) long and extend at least 7.6 cm (3 inches)
40、beyond each end of the heat shield specimen. 4.2 Heat source The method of heating the pipe is up to the discretion of the user. It must be capable of heating the pipe uniformly to 400oC. Since the data and analytical calculation are taken at a perpendicular slice to the heat source, at the centerli
41、ne of the specimen, the temperature of the heat source can drop up to 25oC from one end of the pipe to the other (over the specimen length) without affecting the accuracy of the results. 4.3 RTD temperature sensors The shield temperatures will be measured using RTD temperature sensors with an accura
42、cy of 0.12%. Omega thin film RTD series F elements that are 1 mm thick, 2.3 mm long and 2 mm wide meet the requirements. For materials where the temperature sensors cannot be tack welded directly to the surface, special epoxies can be used. Omegabond OB-500 air-dry cement (Omega Engineering Inc., St
43、anford, Connecticut) or equivalent should be used. 4.4 Temperature recorder A minimum 13-channel digital data recorder with a 0.1oC readout capability. The recorder must have the ability to output to a file that can be formatted to the column designations required for the analytical software program
44、 used in the standard. SAE J2609 Issued DEC2003 - 8 - 4.5 Test stand The shield specimen is supported on a test stand as shown in Figure 2. The test stand is a framed design with an open center area of 65 cm on each side. The shield is centered and supported in the middle of this section by 4 wires
45、running perpendicular to the heated pipe. The wires are 0.81 mm diameter stainless steel Safety Lock Wire and are stretched tight between the sides of the test stand frame, although any small diameter wire will serve the same purpose. The wires are spaced at 10 cm increments starting 10 cm on each s
46、ide of the center of the test stand opening. The purpose of the wires is to allow the specimen to float in space during the testing with little to no energy being transferred from the stand to the specimen or vice-a-verse. 4.6 Shield location It is very important that the center of the shield and th
47、e corresponding RTD sensor be located directly under the pipe during the test. Since the shield must be positioned quickly and accurately under the hot pipe during the test, locator devices providing positive and repetitive positional accuracy should be used to be sure the exact position is obtained
48、. 4.7 Emissometer An emissometer as outlined in ASTM C1371 is used to measure the emissivity of the shield surfaces, top and bottom, prior to the test. Emissometer Model AE from Devices therefore under these conditions, less effective thermal conductivity values will result from this phenomenon. 5.2
49、 Specimen surface condition The surface emissivity of each shield will be measured four times. The first and second measurements will be taken in the as received (new) condition on both the top and the bottom of the shield specimen. These are the values that will be used to satisfy the surface emissivity property requirement. Then for testing and calculation purposes, the specimen will be painted with a high temperature flat black on the top and high temperature flat gray on the bottom and measured a thi
