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1. Introduction The purpose of this study was to evaluate several heat transfer models for predicting the effective thermal conductivity of a high-density fibrous insulation (155.5 kg x [m.sup.-3]) from [...]

7. Model Selection Summary results in terms of the residual standard deviation (RESSD) and Bayesian information criteria (BIC) of the retrospective analysis for data sets 1-11 across all models are [...]

An assessment of uncertainties for the National Institute of Standards and Technology (NIST) 1016 mm Guarded-Hot-Plate apparatus is presented. The uncertainties are reported in a format consistent with current NIST [...]

The analysis and results of a sensitivity study of four procedural variables on the calibration response of two commercial heat-flow-meter apparatuses in conformance with ASTM Test Method C518, Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus, are presented. The apparatuses ranged in plate size from 305 mm by 305 mm to 610 mm by 610 mm and were calibrated using Standard Reference Materials 1450c, Fibrous Glass Board, and 1453, Expanded Polystyrene Board, issued by the National Institute of Standards and Technology. A major objective of the study is to rank the relative importance of the factors and interactions affecting the calibration of the apparatus. Seventy-six runs were conducted under input conditions that varied the mean temperatures from 17°C to 30°C, temperature differences from 17 K to 30 K, heat flow up or down across the specimen thickness, and different circulation bath temperatures. For each apparatus and SRM, the experiment followed a full factorial design for the four factors and included three interspatial replicates to assess for temporal drift. The study revealed that mean temperature and heat flow direction were the two most important test method factors affecting the calibration of both apparatuses. Although the temperature effect was the same for both apparatuses, the heat flow direction effect was found to be instrument dependent. The study also found that the calibration factor for each apparatus was affected by the reference material utilized for calibration. Empirically derived predictive models for each apparatus SRM combination are presented covering the experimental region defined by the input test conditions. [ABSTRACT FROM AUTHOR]

An uncertainty analysis for steady-state thermal transmission properties determined by the National Institute of Standards and Technology (NIST) 1016 mm guarded-hot-plate apparatus is presented for fibrous-glass blanket and expanded polystyrene board. The uncertainties are presented for the guarded-hot-plate apparatus in the single-sided mode of operation covering specimen heat flows from 0.5 to 5 W. The relative expanded uncertainties for thermal resistance increase from 1% to 3.5 % for thicknesses of 25.4 to 254 mm, respectively. Although these uncertainties have been developed for two thermal insulation materials, the results are indicative of other insulation materials measured at a mean temperature near 297 K (23.9°C). This assessment of uncertainties is of particular interest for users of ASTM C177-04 test method that operate similar apparatus at low heat flows (i.e.. near or less than 1 W). Implications for laboratories that develop secondary standards from NIST calibrations are discussed. [ABSTRACT FROM AUTHOR]

Calibration measurements of a commercial heat-flow-meter appara tus are presented. The apparatus has been calibrated using the same specimen of high-density fibrous-glass board over a period of four years, from 1989 to 1993. Seventy-three tests have been conducted, generally at ambient conditions of 24°C with a moderate temperature difference of either 15, 22 or 27°C across the specimen. Variations within a set of data for each test have been examined to verify underlying assumptions of randomness, normal frequency distribution of errors, repeatability, and stability of the data. Variations between test data indicate a small drift, on the order of one percent over four years, in the calibration factor of the apparatus. A model has been developed to describe the small drift with time. The analysis of varia tions between test data has also identified intermittent shifts in the precision of the calibration factor of the apparatus. [ABSTRACT FROM PUBLISHER]