الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
One of the fundamental responsibilities of the National Institute for Standards (NIS) is to
establish, maintain and to disseminate the International Temperature Scale of 1990 (ITS-90) in
Egypt.
Primarily, an adiabatic calorimeter prototype was imported from (LNE-CNAM, France).
This was led to share building a new adiabatic calorimeter in cooperation with the Low
Temperature Laboratory of (LNE-CNAM, France) and the Thermal Metrology Laboratory of
(NIS, Egypt) in order to improve and eliminate most problems related to the first prototype
system and to reduce its associated uncertainty. The main job of the system is to calibrate
Capsule Standard Platinum Resistance Thermometers (CSPRTs) in low temperature range
defined by the International Temperature Scale of 1990 (ITS-90). Thus calibrating CSPRTs
using low temperature fixed points; oxygen triple point (54.3584 K), argon triple point
(83.8058 K), mercury triple point (234.3156 K) and water triple point (273.16 K).
In order to fulfill the requirements of the ITS-90, it is essential for NIS to realize these
temperature fixed-points. Thus a Multicell including the oxygen and argon triple point cells
(already existing) beside two new miniature metallic sealed cells of mercury and water triple
points were developed. Consequently, the multicell compartment having all of the four cells is
inserted inside the calorimeter to work under adiabatic conditions. This enables NIS to
calibrate CSPRTs. These CSPRTs are the NIS standards, which are used in maintaining and
calibrating the substandard thermometers of all research and industrial sectors in Egypt.
Thus, in this thesis, an intensive work has been performed through designing,
fabricating, assembling and studying the two new miniature cells and work of the calorimeter
under adiabatic conditions.
Chapter one gives some reminders related to the thermodynamic temperature concept,
and then introduces the concept of thermodynamic temperature scale with a historical
summary of successively used practical temperature scales and the principles of the latest
International temperature scale of 1990. Then, it uses definitions of thermodynamic states,phase diagrams and phase transitions of substances to clarify the physical meaning of
thermometric fixed points. In the last part of the chapter, full description of the thermal
processes such as adiabatic method and constant heat flux method was given.
Chapter two starts from the thought about the cell, then passing through its design,
choice of material, machining, fabrication, cleaning, filling and its assembly to the adiabatic
calorimeter.
Chapter three starts with installation, preparation. Full description of the system
specifications, its principles, design, dimensions and construction of cryostat with its full parts
and Multicell was given. Detailed description of the used vacuum system and how to control it
was also given in addition to the tests used. The chapter ends with description of connecting
the vacuum system to the calorimeter and with the measuring equipment. A developed
software that controls the whole experiment was also described.
Chapter four starts with full description of the working procedures and all the successive
modifications and improvements needed for proper functioning. Several runs were performed
and analyzed in order to evaluate its performance. The Chapter is ended with a metrological
characterization of the system, thus, giving the optimum working conditions.
Chapter five presents analysis of the uncertainty budget. It describes in details all the
sources of uncertainty, and methods of their evaluations, that affecting the measurements. The
chapter is ended with a table that summarizes all these components in order to obtain the
expanded uncertainty.