DEVELOPMENT OF PROPOSALS FOR THE DECOMPOSITION OF THE SHIP REFRIGERATION UNIT AND THE COMPRESSOR MATHEMATICAL MODEL

Abstract

The aim of the work is to develop proposals for the decomposition of the ship's refrigeration unit and to develop a mathematical model of the compressor, which is the basis for further automation of the relevant processes of assessment and control of the ship's refrigeration unit as a whole. This goal is achieved by analysing the schematic diagram of a ship refrigeration unit with a two-stage vapor-compression refrigeration machine. For the sake of generality, we consider the most complex case of a two-stage refrigeration machine combined with a cold consumer in the form of a freezer complex (system of freezers), and all other cases follow from this as simpler and more partial. At the same time, to solve various problems, in a general sense, a decomposition at three levels is proposed. The first level involves the separation of the ship's refrigeration unit into two main components: a cold generator (refrigeration machine) and a cold consumer. The second level involves splitting the generator and the cold consumer into separate nodes using mathematical models that are synthesized. The second-level breakdown makes it easier to obtain the equations of the mathematical models of the first-level nodes using the simpler equations of the mathematical models of the second-level nodes. The third level of decomposition involves the breakdown of second-level nodes into their constituent elements with the definition of their structural characteristics, which is used in the design of second-level nodes. It is determined that the mathematical models of the decomposition units at the second level contain equations of three types: equations of the first type, which give the relationship between the parameters of the workflow and the design parameters of the unit; equations of the second type relate the design parameters to the weight and size characteristics, and equations of the third type relate the design parameters of the units to their economic characteristics. The most important result of the research is a mathematical model of the compressor in the form of a function of two variables with a transition to a generalized mathematical model of the compressor. Thus, the use of the mathematical models of the compressor discussed in the article makes it possible to solve the problem of computer-aided design of optimized compressor designs and refrigeration machines in general, as well as several other problems of synthesis and analysis of ship refrigeration units.