Analysis of Laminar Mixed Convection Heat Transfer to Supercritical Water Flowing in a Vertical Duct

• In this paper analytical solutions have been obtained for the case of laminar supercritical water flow between two infinite walls at two slightly different temperatures. The existence of the fully-developed flow condition is postulated and thus the problem is reduced to solutions of a set of non-linear ordinary differential equations representing the conservation of mass, energy and momentum. The equations are numerically solved using the Matlab code, and employing water property functions based on the IAPWS-IF97 library. The Matlab program has been verified against known analytical solutions for the laminar duct flow of fluids with constant properties and an excellent agreement has been obtained. The solutions of conservation equations give an expression for the over-all heat transfer coefficient in mixed convection. The analysis indicates that the heat transfer coefficient is a very strong function of local properties and flow conditions. The predicted Nusselt number and the convection coefficient are in a reasonably good agreement with existing correlations once the fluid temperature is far from the pseudo-critical value. However, the existing correlations deviate from the predicted values when the fluid is at the pseudo-critical temperature.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

SRA - Energy

SRA - Energi

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