Bukaros V. Improvement of systems of diagnostics and control of technical condition of ship refrigeration units.

In the dissertation the actual scientific and technical task of increasing energy efficiency and reliability, improving the means of diagnosis and monitoring of technical condition by using simulation models of individual components of ship refrigeration units was solved. The conducted analysis of problems and trends in the development of ship refrigeration equipment allowed identifying the main tasks of diagnosing and monitoring the technical condition of the main components of ship refrigeration units. Choice as the object of research of steam compression low refrigeration capacity ship refrigeration units with hermetic and semihermetic compressors was justified. A comparative analysis of the literature has shown that in the selected areas of research the most promising approach is "fault detection and diagnostics" using mathematical modeling of individual nodes of the ship refrigeration units. Based on the thermodynamic analysis of ship refrigeration units operation cycle the main parameters of the operation were revealed and the simulation model of ship refrigeration units temperature modes was improved. Based on this model an algorithm and a subsystem for estimating the heat transfer coefficient and the predicted diagnostics of evaporator icing was developed. The algorithm was tested by means of simulation. The analysis of the reciprocating compressor dynamics was carried out and allowed to reveal the main parameters of the compressor operation. Based on this analysis and the theory of adaptive full order state observers a model of the compressor state observer which is able to determine energy and mechanical parameters in real time to diagnosing and monitoring the technical condition of the compressor was developed. The energy analysis of the ship refrigeration units refrigeration cycle was carried out and allowed to determine the perfection indicators of the refrigeration cycle. A method for calculating the parameters of the actual refrigeration cycle was developed and compared with other sources. On the basis of the specified technique the general algorithm and a subsystem of an estimation of ship refrigeration units energy efficiency with using the compressor adaptive state observer are offered for the first time. Simulation models of condensing pressure stabilization processes of air- and water-cooled condensers were developed and studied. Based on the developed models the ship refrigeration units condensing pressure stabilization system was improved. It differs in using additional feedback on the cooling water flow and temperature channels and the presence of a logic switching device in the pressure regulator circuit which gives the system the properties of robustness in relation to disturbing actions, improves its dynamic performance and allows to increase the energy efficiency of the ship refrigeration units as a whole. Based on the symptom and fault correlation chart recommended by Wilhelmsen Ships Service Company a method for identifying symptoms and detecting ship refrigeration units faults using predictive diagnostics and "fault detection and diagnostics" approach was proposed. The method is based on the construction of an actual refrigeration cycle with subsequent comparison with the "reference" refrigeration cycle and the detection of typical deviations. On the basis of the developed algorithms and subsystems the general system of diagnostics and control of a technical condition of ship refrigeration units with use of the minimum necessary set of sensors was offered. Keywords: ship refrigeration unit, energy efficiency, diagnostics, technical condition monitoring, state observer, simulation.