Kovalchuk D. Energy-Efficient Automatic Control of the Heat Utilization from Gas Boiler Combustion Products in the Conditions of SteamCompression Heat Pumps Application

The new solution of the actual scientific and technical problem of increasing the energy efficiency of combustion products heat recovery process of gas boilers by improving the algorithms of its automatic control system is presented. A physical model of the combustion products heat recovery process, using a heat pump was developed and implemented. The main set of 64 long experiments in the automatic mode was carried out on the physical model, the results of which formed the basis for the development of the statics and dynamics models of the process as a control object. In result of special experiments on the physical model, the expediency of introducing a new adjustable variable – the calculated value of the refrigerant mass flow in the evaporator, which further increase the efficiency of refrigerant flow control to the evaporator and simplify the technical implementation of control system. The structure of the refrigerant vapor superheat temperature control circuit at the evaporator outlet has been improved to prevent self-oscillations by applying a microstep mode in the control valve. Based on the equations of material and energy balances of the combustion products heat recovery process and the results of experiments on its physical model, a set of mathematical models describing nonlinear static and dynamic properties of control channels, cross channels, and perturbation channels of the combustion products heat recovery process with a heat pump as control object is obtained, and a simulation version is implemented. The adequacy of models is confirmed, the mathematical basis for development of algorithms with increased dynamic accuracy of control system is created. The concept of increasing the efficiency of controlled processes, in the energy efficiency of the combustion products heat recovery process, based on the consideration of control object as an integral object, integrating all identified and mathematically described channels of relationships between its variables, by purposefully improving the control algorithms to increase dynamic accuracy based on the application of the principles of cascade, invariance and autonomy. Synthesis and comparative researches of control systems variants with basic control algorithm and alternative variants of algorithms increasing dynamic accuracy of controlled variables with estimation of energy efficiency of process are carried out. A simulation model of external perturbations of the combustion products heat recovery process a t a time interval equal to one year was obtained, based on the monitoring data of the autonomous gas boiler house of a residential building.