The present study aims to explore the methodologies employed in practice to ascertain the parameters of processes occurring in supercritical fluid media. A primary focus of this investigation lies in the solubility of key components of the system in supercritical fluid solvents, with a view to understanding the limitations of mathematical models in qualitatively predicting solubility outside the investigated ranges of values. This analysis seeks to elucidate the potential challenges and opportunities in conducting experimental studies in this domain. However, within the domain of supercritical fluid technologies, the optimization of processes and the prediction of their properties is attainable through the utilization of models and machine learning methodologies, leveraging both accumulated experimental and calculated data. The present study is dedicated to the examination of this approach, encompassing the consideration of system input parameters, solvent properties, solute properties, and the designated output parameter, solubility. The findings of the present study demonstrate the efficacy of this approach in predicting the solubility process through machine learning.

Keywords: supercritical fluids, solubility of substances, solubility factors, solubility prediction, machine learning, residue analysis, feature importance analysis

A laboratory circuit of the installation with a heat exchanger-supercharger in the hot water circuit of the boiler has been developed. The conducted studies have shown that the temperature of hot water at the outlet changes depending on the oscillation frequency of the electromagnetic valve at a given flow rate, and the highest efficiency of water heating is observed at a frequency of 1.75 Hz. Calculation of the heat transfer coefficient showed that at a steady-state flow rate, the heat transfer coefficient of the heat exchanger-supercharger is 180 W / (m ^ 2 ° C). Then, with increasing frequency, the heat transfer coefficient smoothly decreases and reaches a minimum of 173 W / (m ^ 2 ° C) at 1.0 Hz. With a further increase in frequency, the heat transfer coefficient begins to increase and reaches a maximum of 188 W / (m ^ 2 ° C) at 1.75 Hz. As a result of the experiment, it was also found that with increasing frequency, the flow rate in the hot water circuit increases and reaches a maximum at a frequency of 1.75 Hz Q = 0.6 l / sec. That is, at such a frequency, the heat exchanger-supercharger, due to the oscillations of the liquid flow in the first circuit (cold water circuit), most effectively transmits the oscillations of the flow to the second circuit (hot water circuit), which can be used to reduce the power of the pump in the hot water circuit at this frequency.

Keywords: heat exchanger-supercharger, heat transfer coefficient, electromagnetic valve, water hammer

In this work, an experimental model of a circuit diagram with pulsating circulation of a liquid coolant in a heated circuit of a plate heat exchanger was assembled and tested. As a result of hydraulic and energy calculations of the circuit, the optimal parameters for flow, pressure, and temperature of the coolant were selected at maximum efficiency of the impact unit. It has been established that with an increase in the operating frequency of the impact unit, the heat transfer coefficient of the heat exchanger first decreases and reaches a minimum of 452.47 W/(m2*0C) at a frequency of 0.5 Hz, and then begins to increase and reaches a maximum of 482.31 W/(m2* 0C) at a frequency of 2 Hz, after which it gradually decreases. It has also been experimentally established that the temperature at the outlet of the heat exchanger of the heated circuit increases with increasing frequency of the shock unit and reaches a maximum at a frequency of 2 Hz, after which it begins to gradually decrease. It has been established that the change in temperature at the outlet of the heat exchanger of the heated circuit exceeds the change in temperature at the outlet of the heat exchanger of the heating circuit at operating frequencies above 1 Hz, which is due to the stronger influence of cavitation at these frequencies.

Keywords: heat exchanger, heat transfer coefficient, impact unit, frequency, heat transfer