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High heat transfer rate and low pressure drop for a given boiling conditions of the refrigerant is achieved when the difference between the mean temperature of the inner wall of the pipes tТ and the saturation temperature t02 at the outlet from the boiling zone becomes minimal. It takes into account both the irreversible losses caused by the presence of a finite temperature difference, and the effect of the evaporator’s hydraulic resistance on the performance of the compressor. Existing optimization techniques for this criterion only apply to traditional refrigerants and use obsolete formulas to determine the heat transfer coefficient. The numerical method allows to take into account more factors influencing the process of boiling both traditional and alternative refrigerants. Using the computer program in a rather wide range of initial data determining the boiling conditions of the four refrigerants, optimal values of the mass velocity (wρ)о are chosen at known heat flux densities q. After the modification of the program, the optimum length of boiling zone values lко are chosen for the given values of the heat load Qз and other combinations of the initial data. By regression analysis of the chosen results, power dependences are obtained for an approximate determination of the optimal parameters. The values of the power-law coefficients for calculating the basic variables sought are presented in two tables of text. Based on the analysis of the recommendations published in the domestic literature, formulated following the results of an experimental and analytical study of efficiently operating evaporators, it was proposed to introduce, when optimizing, restrictions on the temperature difference tТ and t02, and also on the vapor velocity leaving the boiling zone. To remain within the permissible limits, it is recommended to change the values q and Qз, as well as the internal diameter of the pipes dT and the vapor conten x1 at the refrigerant inlet to the evaporator.

vestnik gosudarstvennogo universiteta morskogo i rečnogo flota imeni admirala s. o. makarova/vestnik gosudarstvennogo universiteta morskogo i rečnogo flota imeni admirala s.o. makarova

ACCOUNT OF LIMITS DURING OPTIMIZATION OF REFRIGERANTS IN-TUBE BOILING PARAMETERS IN SHIPBOARD EVAPORATORS