Thermophysical Property Data Research Articles

A flexible thermophysical property information system for chemical engineering and chemical process design

The DETHERM data bank system provides thermophysical property data for chemical process design. DETHERM comprises: 1) a Data Retrieval System for storage and recovery of data from the literature, 2) a Data Calculation System for computing phase equilibria and mixture and pure substance properties from sets of pure substance basic data, and 3) a Data Analysis System for obtaining sets of basic data by regression and thermodynamic consistency tests. DETHERM is available on-line and for in-house installations.

Reference materials and evaluation of thermophysical properties data

This paper presents a general review of the governmental activities in Japan on reference materials and evaluation of thermophysical properties data and then describes recent developments at the National Research Laboratory of Metrology (NRLM) in the field of thermophysical properties and related standards. As for reference materials, the past and present activities organized by the government and a few related associations are reviewed from the point of view of establishing traceability systems, whereas, on the evaluation of thermophysical properties, the framework of collaborative research for establishing data base systems by network sharing is mentioned. Then the recent studies of NRLM on the measurements and standards of thermophysical properties as well as its calibration services are summarized.

High current brushes: VIII: Effect of electrical load

Performance data are presented from controlled experiments with Ag-graphite brushes sliding on copper slip rings in a continuous-operating mode over a wide range of electrical loads (0.8 – 8 MA m −2) in a humidified CO 2 environment. The observed contact resistance, friction and wear characteristics are explained on the basis in part of past and recent contact models and in part of thermophysical property data acquired for the specific Ag-graphite brush material (mass fraction of silver in graphite, 0.75). The phenomenon of electromigration of silver is invoked to explain observed consistent asymmetry in contact resistance between anode and cathode brushes. Direct evidence in support of the models and observed brush performance is offered from results of detailed contact surface morphology and structure analyses.

THE BRADFORD DISTRIBUTION

The distribution of references in a collection of pertinent source documents can be described and predicted by the relation where the parameter ß is related to the subject field and the completeness of the collection. The model is used to predict the reference yield of abstracting journals in a search for thermophysical property data. It is used also to explain differences among various literature studies of the past in terms of differences in subject and comprehensiveness of search. The model is derived from S. C. Bradford's ‘law of scattering’ and is called the Bradford Distribution.