Heating chamber in vacuum furnace is closed thermal system where heat exchange is predominantly radiant. Conductive heat exchange is defined by well-known formulas. In order to determine the temperature condition of the object during heating (cooling), it is necessary to determine the angular coefficient of radiant exchange on every other objects. The known in the literature methods, including the geometrical once, have a solution for heat exchange only between two objects. The applications for real heat systems is partial and limited. It is presented a geometric model for calculation the angular coefficients of radiant interchange for closed thermal system. Heat exchange is taking place between an unlimited number of objects and a free-standing arrangement between them. The model allows solutions for objects of different geometric form in the presence of intermediate objects, as well as barriers for heat radiant from their own surfaces. The paper has been verified by a solution of thermal problems for vacuum furnaces.
Author: Ronkova V.
The main objective of the presented research is to improve and upgrade the existing methodologies for design and layout of test machines and equipment. The authors’ team has a significant experience in creating new test machines in the area of Machine Science, Machine elements, Automation and Measuring. The application of CAD systems within this research process of multivariate design is an additional advantage for the evaluation and analysis of different layout versions for the elaborated new test machines. The priority of combining electronic and mechanical measuring options is pointed out. The improved methodology is applied within the design process of a test machine for the experimental research of cardan drives.
The paper justifies the importance of the experimental determination of rotational variability of cardan drives and couplings.
The objective of the authors’ team was to elaborate a new automated test machine for the determination of this variability. The principle design of this new automated test machine is described in details. The advantages of the application of electronic measuring equipment in combination with PC for the automation of the measuring and experimental data processing are pointed out. The test machine gives opportunities for changing of the angles between the driving and the driven shaft and for regulating the rotational speed of the driving shaft.
The other functions of the electromechanical test machine are described in details in the paper. Conclusions are made: the methodology for experimental research of rotational variability of cardan drives is improved; the application of electronic test machine verifies the advantages of the usage of high sensitive and precise sensors of new generation; contemporary approaches are applied.