An Evaluation of the Dow Thermal Performance Prediction Model for a Database of XEPS/CFC-12 Aged Resistivity and Physical Properties

Abstract

For a number of years, The Dow Chemical Company has been using a semi-empirical model for predicting long-term insulation performance for the quality assurance process of STYROFOAM* Brand Insulation Board.

The predictive capability of this model will be compared against aged samples. These results are selected from a database of resistivity measured on extruded polystyrene boards manufactured with CFC-12 as the captive blowing agent

In addition to the resistivity, other physical properties that are typically used for product specification and quality assurance are included in the database

The key features, input data, computer hardware requirements and limitations of this performance model are described in relation to the input data range and addi tional data (e.g., other than foam properties) that are required to run the model.

The predictive performance was demonstrated for two stages of the aging process (the air influx and blowing agent emission) for samples varying in thickness from 1 to 6 inches. The overall relative standard deviation from the prediction-measurement regression was 2.5 percent, while thermal resistivity varied from 44.4 to 30.5 m °K/W (6.4 to 4 4 ft² hr °F/Btu in)

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