ARTICLE:

• Literature Review of Heat Transfer in Thermometric Fixed Point Cells  download article

Humayer Chowdhury
University of Technology Sydney, PO Box 123 Broadway NSW 2007; and National Measurement Institute, PO Box 264 Linfield NSW 2070, Australia

Mark Ballico
National Measurement Institute, P O Box 264, Lindfield, NSW 2070, Australia

Jafar Madadnia
University of Technology, Sydney, P O Box 123, Broadway, NSW 2007, Australia

John Reizes
University of New South Wales

ABSTRACT

The melting and freezing phase transitions of thermometric fixed point cells are used as a reference point for the International Temperature Scale ITS-90. These cells can achieve reproducibility of 0.1 mK, and international equivalence of such cells is at the level of 0.5mK. This paper reviews and examines existing literatures to identify controlling factors and to suggest research approaches which will be employed in developing heat transfer models for the freezing and melting process of fixed point cells. Presently at the National Measurement Institute Australia, thermal model for melting and freezing phase transitions are being developed. However, the requirement for lower uncertainties in the international definition of temperature have tended to make the use of these cells at the required accuracy time consuming, requiring significant fine-tuning of furnaces and measurement techniques. In addition, some present practices and techniques, whilst effective, are not well understood from a heat transfer and physics viewpoint.

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