The article considers the construction of an algorithm for estimation the energy efficiency of a ship refrigeration unit using the minimum required number of sensors. It is established that the existing methods for diagnosing and monitoring the technical condition of ship refrigeration units are imperfect due to the presence of a large number of sensors and the necessity to suspend the unit. The choice of the refrigeration coefficient as an indicator of energy efficiency is justified. A method that allows determining the refrigeration coefficient in real time without the necessity to stop the operation of the ship's refrigeration unit and use pressure sensors is proposed. For this, the method supposes the calculation of the specific cooling capacity and compressor compression work, the mechanical power on the shaft and the mass flow rate of the refrigerant. The algorithm for determining the cooling capacity and compression work using only four temperature sensors is considered. This algorithm supposes the determination of enthalpies at characteristic points of the refrigeration cycle using the equations of the refrigerant state. A method for evaluating the mechanical power on the compressor shaft using full order adaptive state observers is proposed. A decision of using the electromagnetic torque of the compressor motor as a measured quantity is substantiated. A state observer is synthesized using a modal method based on a linearized model of the electric motor. An expression for calculating the geometric mean root and elements of the observer matrix is proposed. The resulting observer structure allows constructing it on the basis of a complete mathematical model of the electric motor and evaluating not only the speed, but also the load torque on the compressor shaft. In the environment of Matlab / Simulink, a simulation model of the compressor motor state observer is built. The obtained simulation results confirm the efficiency of the proposed method. An algorithm for determining the electromechanical parameters of a compressor for a given period of time using three voltage and current sensors is considered. A general algorithm for estimation energy efficiency, which can be the basis for creating a system for diagnosing and monitoring the technical condition of a ship refrigeration unit, is constructed.
In the article energy efficient ways of the condensing pressure (temperature) control in refrigeration units for various purposes are considered. The comparative analysis of the circuit solutions of the condensing temperature regulators for air cooling condensers is conducted with simulation methods. Modeling of the single-phase system of the regulator pulse-phase control triac HPC1/4 showed that this system has a low power factor. The feasibility of the condensing temperature regulators implementation on the basis of the three-phase frequency converter with DC chain is substantiated for the low and medium cooling capacity refrigeration units. The disadvantages of the existing systems of the condensing pressure stabilization of the refrigeration units water cooling condensers are highlighted. The research of two proposed control systems of the water-cooled condensers of the medium and high cooling capacity refrigeration units is conducted. It is established that the using of the principles of partial invariance to main disturbances with elements of the nonlinear correction can improve the energy efficiency of refrigeration units. Also it is provided by modeling the processes in the shell and tube capacitor KTP-300 of the ship refrigeration unit that the using of variable structure systems further improves the dynamic quality of control processes with large fluctuations of the heat loads.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.