In presentday world heat pumps are used still wider both in civil sphere and in industry. But the efficiency of heat pumps operation depends greatly on environment parameters. At low temperature of outdoor air the heat exchange surface of a heat pump evaporator begins to get covered by a frost layer that influences much the efficiency of the plant operation as well as its life time. So, the problem to search for thawing methods is urgent as well as for methods to prevent the frost formation on heat exchange surfaces. The paper examines the major wellknown methods of thawing, new developments and investigations in this sphere. The advantages and disadvantages of the methods presented are discussed. The most perspective and applicable methods are marked out. The criteria of selection were as follows: the possibility to thaw out using the methods without stopping operation, efficiency and the simplicity of realization.
The article continues the theme of the use of the latest scientific achievements in the field of formation of ice covers and modern methods of inventory preparation in highspeed sports. The first focus is on the problem of the stability of the athlete when cornering at high speeds turns. The article presents the main chronological stages of improving the design of blades for ice sports. The physical features of interaction between ice and athlete skate when cornering and the results of investigation of influence of the properties of the ice cover and the configuration of the blade ridge on the athlete’s stability in short track are considered. Experimental equipment, which allowed to simulate the passage of an athlete turns and a comparative analysis of highspeed properties of various configurations of blades are developed. Experimental data of the influence of the profile and form of the modified blades on the highspeed characteristics were obtained and was offered their new design: the blade has a bend radius and the bearing surface, the angle of sharpening the inner edge of the blade is less than 90 о. Experiments have shown that the proposed design of the blades improves the stability of the athlete during turning, as well as increases the speed characteristics. It is shown that the formation by laser ablation structure on support and lateral surfaces is necessary to improve the speed characteristics of curved blades. It gives a skater advantage at the start and during the race in short track.
The paper presents the analysis of the process of heat exchange during water ice formation on the inside surface of a tubular element. A generalized equation that makes possible to calculate the thickness of water ice formation was derived. The pilot test bench and methods of obtaining data on dynamics of ice formation are described. Experimental data are compared with the results of a theoretical calculation using the model presented. The method to determine an optimal thickness of the water ice layer is offered. It may be used when calculating ice generators with different surfaces where ice formation takes place (flat surface, external and inside surface of a tube). The optimal thickness of water ice under conditions adopted during the experiment was calculated using the method offered. The study performed is urgent when calculating ice generators and cold accumulators of tubular ice in which water ice formation takes place on the inside surface of the tube.