Kuropyatnyk O. Providing of the sea vessels ecological exploitation

The dissertation research is dedicated to the solution of a scientific and applied problem – definition of exhaust gases control systems optimum modes (from the point of view of maintenance of the maximum decrease of nitrogen oxides concentration and stabilization of the reached value at the level corresponding to the requirements requested by the international qualification societies) at simultaneos minimal decrease of energy and economic parameters of internal combustion engines of river and sea transport vessels. The main motivation for research is the current availability of requests for practice: solving the problem of minimizing the emission of nitrogen oxides from the exhaust gases of diesels of river and sea transport vessels; the need to ensure the environmental efficiency of the seagoing vessel. The main task of the research is to develop and determine the modes of operation of exhaust gases control systems that ensure the environmental parameters of ships in accordance to international standards. To solve the main task of the study, the following auxiliary tasks are solved: 1) determination of the gas recirculation system operation range, which provides the maximum reduction of nitrogen oxides emission while minimizing the increase of fuel consumption; 2) determination of the criterion for evaluating the efficiency of the exhaust gas recirculation system; 3) determination of optimal (from the point of view of ensuring the ecological compatibility of seagoing vessels) modes of exhaust gas bypass; 4) analysis of changes in static and dynamic parameters of diesel engines of river and sea transport vessels during gas bypass. As a result of solving the main and auxiliary tasks, a scientific position is obtained: the ecological compatibility of marine vessels is ensured by integrated control of exhaust gases of internal combustion engines through using the recirculation and bypass systems, herewith the optimal operating modes of these systems are determined by fast-moving or by load conditions modes of diesels operation. The scientific position is substantiated by scientific results: first installed: optimal (from the point of view of the maximum reduction of emission of nitrogen oxides, at the minimum decrease of effective power and the minimum increase of the specific effective fuel consumption) the range of recirculation of exhaust gases which is 12,5…15,5 % and in which the stoichiometric ratio is maintained, that provides straight hypergolicity of the fuel; criterion for evaluating the efficiency of the exhaust gas recirculation system (for which it is advisable to take the area as a function NOx, allowing a quantitative and qualitative comparison of the modes of its operation; optimal (in terms of closer to the maximum reduction of nitrogen oxides emissions with a simultaneous minimum increase in fuel consumption) mode of bypass of exhaust gases, which is 4…6 % and which prevents the occurrence of thermal overvoltage and surges; the possibility of using the exhaust bypass system is limited by partial (in the range of less than 55 % of rated power) load modes and increased (in the range of more than 9 %) bypass modes. The method of determining the concentration of nitrogen oxides in the exhaust gases has been improved, which differs from the existing ones by the possibility of estimating their relative value (in terms of power and operating time of the diesel engine) by the final oxygen concentration in the exhaust gases. The method of load distribution between parallel-running diesels taking into account their ecological indicators (content of nitrogen oxides in exhaust gases) was further developed. The practical significance of the results is as follows: for the main operating ranges of the main and auxiliary engines of river and sea transport vessels the mode of operation of recirculation/exhaust gas transmission systems is established, the use of which increases the ecological efficiency of the vessel with simultaneous minimum (not more than 2.5…3.0 %) power deviation and prevention of thermal stress; the technology of complex control of exhaust gases should be used during steady-state operation of the ship's propulsion system, and recommendations for determining the optimal modes of its operation – during the design for the installation of recirculation/bypass systems. Key words: river and sea transport vessels, ecological compatibility, emission of nitrogen oxides, exhaust gas recirculation, exhaust gas bypass, exhaust gas management.