No abstract

The subject of our research is a scroll compressor. With its large number of advantages over reciprocating compressors in the form of overall, mass and production characteristics, they have their own difficulties associated with the theory of stability of a movable scroll during the operation process. As you know, a complex system of forces acts on the spiral, is very variable in magnitude and direction, for the period of one orbital revolution of the spiral. It should be noted that in modern designs of scroll compressors in the axial direction, a movable scroll has most often a one-sided rigid support - a thrust bearing. Moving the movable spiral in the opposite direction is limited only by the force of the gas axial pressure, which does not guarantee it saving its original position, at least within the gaps, touching the movable and stationary spirals, which is unacceptable. Next, we consider the basic calculation equations associated with the stability of a moving spiral.

Compressors are necessary to provide consumers of ship power systems and the ship as a whole with compressed air of various pressures and flow rates. The correct functioning of water transport infrastructure depends on the correct selection of compressor equipment. This makes it necessary to consider this issue in detail. If all the variables, the compressor selection parameters under consideration, were measured in the same scales and units of measurement, it would be possible to add up all the values, but this approach is very rough. The output is to normalize the values of variables, and then calculate the final criterion based on them. The article deals with the selection of compressor equipment for the ship's starting and working air systems using exponential and linear normalization methods. For statistical processing, certain parameters of compressors from domestic and foreign manufacturers are proposed. The result of the study is to obtain one formal criterion the final rating, instead of several qualitative parameters. Based on the obtained value, the optimal compressor is determined by the combination of its characteristics. The next stages of data processing are the proposal of maximum likelihood and logistic regression methods. The probability of assigning a compressor with a certain set of characteristics to a positive or negative class is simulated. The model was trained based on the available training data for selecting compressors.

Objective. With the decreasing use of refrigerants with a high global warming potential, increasing the efficiency of refrigeration machines using natural working fluids is a very urgent task. The CO2 booster refrigerant cycle may be optimal for the fields of commercial refrigeration, climate engineering and heat pumps, but needs to be adapted to regions with hot climates. The purpose of the study is also to systematize possible ways to improve the spiral technology, as a guarantee of increasing the efficiency of booster refrigeration machines.Method. Such solutions have already been tested by increasing the transcritical cycle efficiency through the use of an ejector and parallel compression. However, the use of a scroll compressor in the transcritical cycle may be a good alternative to these methods. This solution, a little bit improves technical and economic indexes of the refrigerating machine, in the most part reducing capital and operational costs. When considering the prospect of improving the efficiency of a booster system with scroll compressor, it is necessary to address the issue of compressor performance optimisation. An issue of this kind can be referred to improving the efficiency of the booster system, at the expense of the internal characteristics of the refrigeration machine.Result. Thus, in this paper, a conceptual approach is considered to solve this problem based on a system analysis of the interconnection of the compressor as the main energy-intensive element of a refrigeration machine.Conclusion. Development of conceptual model, allows to identify influence of various factors on scroll compressor operation and to build adequate mathematical model, to choose or develop necessary calculation methods.

The scroll type compressor is widely used in the medium capacity segment of refrigeration and air conditioning technology including heat pumps. Today there is an active process of changing from hydrofluorocarbons to natural refrigerants with low global warming potential. CO2, with its low critical point and correspondingly high operating pressures, is gaining in importance. For operation with new refrigerants, the scroll compressor has to be adapted to take account of all its design features, the most important of which are the clearances in the machine's flow area. It has to be considered that the thermodynamic properties of carbon dioxide, different from hydrofluorocarbons, have a significant influence on the volume and energy values of the compressor. In this case relevance consists in increase of accuracy of compressor losses calculation and prediction of refrigeration machine characteristics. As the basic volumetric losses in the scroll compressor are leakages of working substance in its working part, and the process of flow of medium is unsteady, their quantitative component causes interest. The purpose of this work is to clarify the physical basis of the leakage process in the radial clearance and the degree of influence of various factors on it. Such analysis gives further opportunity to refine the methodology of calculation of leakages of compressed medium, taking into account the mobility factor of gap walls. It will raise accuracy of the received results which can serve as a base to prognosis of optimum characteristics of the compressor, due to their approximation and will allow to optimize designing of refrigerating machines at the chosen modes of work.