The deformation characteristics and the roll force are of significant importance in the rolling of seamless steel tubes with a tandem skew rolling (TSR) process. In this paper, finite element methods and dual stream functions are utilized to analyze tube rolling with the TSR process. Finite element simulations reveal the deformation characteristics of the seamless steel tube during the rolling process. In addition, the kinematically admissible velocity field and the strain rate field of the deforming tube are described and derived in terms of the dual stream functions. The roll force in theoretical analysis is obtained through upper bound analysis. Experiments are carried out in a TSR testing mill on a carbon steel, to show the validity of the analysis. The curve of the roll force in the process is obtained and the variation of the roll forces is analyzed in detail. Through the comparison between the theoretical, numerical, and experimental investigations, the constructed analysis model is used to study the TSR process and establish a theoretical basis for further development of the process.

A prototype of miniature vapor compression heat pump system was introduced. On the basis of compressor, capillary, condenser and evaporator models, the steady-state model of air-to-water miniature heat pump system is developed with regard to energy and refrigerant inventory conservations among all these components. The results show that the relative error between prediction and experiment values is less than 5%, and the optimal match of condenser and evaporator lengths were obtained by simulation program.

A series of tests was carried out on the hydrophilic surface that was made of a new hydrophilic anti-frosting paint with the character of restraining frost growth. Compared the result with prevenient hydrophilic paint, the new paint presented in this paper has better effect on retarding frost formation under low and high relative humidity environment and the thickness of the coat made by the new paint was only 0.06mm, that was only 20 percentage of film thickness of prevenient paint.