Calculation of the Thermohydraulic Efficiency of Porous Direct-Flow Steam-Generating Channels
- PDF / 2,752,933 Bytes
- 12 Pages / 594 x 792 pts Page_size
- 85 Downloads / 137 Views
Journal of Engineering Physics and Thermophysics, Vol. 93, No. 5, September, 2020
CALCULATION OF THE THERMOHYDRAULIC EFFICIENCY OF POROUS DIRECT-FLOW STEAM-GENERATING CHANNELS A. P. Lukisha
UDC 621.18-027.236
Results of calculation of the efficiency of porous direct-flow steam-generating channels in the transition region of motion of a heat-transfer agent with boundary conditions of the first kind have been presented. The obtained data have been compared with the results of calculations for a smooth-walled tube. It has been shown that positive values of geometric coefficients of efficiency of such a channel can be obtained when water is used as the heat-transfer agent. For the investigated parametric range of the indicated channels, no positive values of energy coefficients of efficiency were found. The dependences of the efficiency coefficients of a porous model channel on its basic operating-structural parameters have been analyzed. Keywords: thermohydraulic efficiency, porous steam-generating channels, heat-transfer agent, water, boundary conditions of the first kind. Introduction. The limitedness of world power resources requires that energy-saving technologies be found. One line in this field is to investigate the possibility of using energy-efficient porous heat-exchange elements. The earlier numerical and computational study of the thermohydraulic efficiency of porous heat-exchange channels during the single-phase motion of a liquid heat-transfer agent in them [1–5] has shown the presence of operating-structural parameters of such channels at which their energy gain is possible compared to smooth-walled heat-exchange channels. However, investigating the issue of thermohydraulic efficiency of porous high-thermal-conductivity channels during the evaporation of the heat-transfer agent in them is of prime interest. An analysis of the literature sources [6–8] has shown that most of the thermophysical investigations of boiling and evaporation of the heat-transfer agent in smooth-walled and porous channels were conducted for boundary conditions of the second kind, i.e., at a constant heat flux on the channel wall. However, as the investigations of the thermohydraulic efficiency of porous channels during the flow of a single-phase heat-transfer agent in them has shown, the energy effect can be attained with boundary conditions of the first or third kind, i.e., when a constant temperature or the law of heat exchange with the ambient medium with a known temperature are assigned on the channel wall. The present work seeks to investigate the thermohydraulic efficiency of porous cylindrical channels compared to smooth-walled cylindrical channels during the evaporation of the heat-transfer agent (water) in them with boundary conditions of the first kind. A smooth-walled tube operating as a once-through steam generator is selected as the basic surface. Calculation of the Boiling Heat Transfer of the Heat-Transfer Agent in a Cylindrical Smooth-Walled Channel. Zone of developed boiling. It is assumed that the liquid (wate
Data Loading...
