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
The paper proposes and calculates a scheme of a two-stage gas turbine plant using carbon dioxide as a working fluid in the second stage and using heating of the CO2 circuit, as well as heating water sent for heating. As a result, the following were calculated: for the first stage turbine: parameters of fuel combustion products; air compressor parameters; fuel compressor parameters; combustion chamber parameters for a real Brayton cycle; Efficiency of the first stage turbine; for the second stage of the gas turbine: a schematic diagram was drawn up using liquid CO2 as a working fluid; calculation of CO2 parameters at key points of the Brayton cycle; the efficiency of the turbine of the second stage is calculated.
Keywords: energy efficiency, gas turbine plant, carbon dioxide, pressure, pressure ratio, combustion chamber, recuperator