Comparison of the analytical solutionof efficieтcy regenerative rotating heatexchangethe device with resultsof numericalcalculations

Abstract

The article is devoted to the thermal-hydraulic calculation of the rotating heat exchanger of a gas turbine engine. More specifically, the purpose of this work is to determine the error of the known analytical calculation of the efficiency of the regenerative heat exchanger in comparison with numerical calculation. Analytical and numerical calculations of the rotating heat exchanger are performed. The main problem of creating a methodology for the analytical solution of processes occurring in rotating heat exchangers is that it is necessary to solve the problem of non-stationary heat transfer from the hot coolant to the coolant through the regenerator packing. The solution of any non-stationary process of heat transfer requires knowledge of the boundary and initial conditions of the process. As initial conditions, it is necessary to use the dependence of the regenerator packing temperature field on the steady state of its operation. Such a relationship can only be obtained after the calculation is completed. In this case, the solution of the heat transfer problem in a rotating heat exchanger is possible using two methodological approaches. The first possibility is a solution by successive approximations. In addition to the fact that such a technique is very time-consuming, it allows us to obtain only a numerical solution of the problem, the possibilities of analysis are limited. The second possibility is the use of one or several assumptions. Such an analytical solution was obtained by Stepanov G.Yu. It is clear that the use of assumptions in analytical analysis or in analytical calculations requires an assessment of the accuracy of the methodology. An estimate of the accuracy of the analytical solution to the efficiency of a rotating heat exchanger is given in the proposed work. It is shown that the error of the analytical solution of the regenerator efficiency in the zone of high regeneration degree values is insignificant in comparison with numerical calculations. Analytical solutions proposed by Stepanov G.Yu., are accessible and effective in the process of creating regenerators. Of particular importance are analytical calculations of the efficiency of regenerators when recording solutions in the form required by the similarity theory. An increase in the error in the analytical calculation of the efficiency of the regenerator is noted with a decrease in the ratio of the water equivalents of the heat-transfer packing of the rotating heat exchanger and coolants (gas and air). Marked increase of error of the analytical calculation of the effectiveness of the Regener-Torah in the decrease of water equivalent heat transfer gaskets. no-return heat exchanger and coolants (gas and air).

Keywords

the heat exchange device / regenerator / efficiency of a regenerator / the theory of similarity / criteria of similarity in processes of a heat transfer / a water equivalent

References

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RIGHTS & PERMISSIONS

Kalnitsky F.E., Kostyukov A.V.