Methods for the Determination of the Heat Transfer Coefficient in Air Cooled Condenser Used at Biomass Power Plants

Abstract

In the present work, its show a summary of functional relationships developed for the application of dry condensation systems to Biomass Power Plants that present difficulties with access to water for condensation. The bibliographic review reveals the limitations of the analyzed works, in terms of the development of mathematical models and empirical correlations that allow evaluating the simultaneous effects of the surrounding meteorological variables on the average coefficient of heat transfer and the effect on the environment of the use of dry condensation. The analytical study is based on the weak solutions and their correlation with experimental quantities available in research already established in the area of action, a procedure is developed for the calculation of the average coefficients of heat transfer that includes the influence of local climatologically variables, the effect of the spatial distribution of the tubes package on the refrigerant and the confined confinement in inclined components, which increase the reliability of the thermo-hydraulic analysis and suppresses the need for the use of excess areas required by current methods. The proposed models and correlations allow the preparation of a procedure, by means of which all the possible operative variants are evaluated.

Contour integration for the view factor calculation between two rectangular surfaces

“…For Case 2 the integration limits (see Figure 4) are given by 30 $$${F}_{12}=\frac{1}{\pi {A}_{1}}{\int }_{y}^{y+b}d{y}_{1}{\int }_{0}^{a}d{x}_{1}{\int }_{x}^{x+c}d{x}_{2}{\int }_{0}^{d}\frac{{h}^{2}}{{\{{({x}_{1}-{x}_{2})}^{2}+{({y}_{1}-{y}_{2})}^{2}+{h}^{2}\}}^{2}}d{y}_{2}.$$$…”

“…To evaluate Equation (28) the following substitutions are made 30 $$$X=W/D;\unicode{x02007}Y=L/D;\unicode{x02007}R=\sqrt{{X}^{2}+{Y}^{2}}$$$…”

“…Coordinates for view factor in inclined planes. fraction of the radiative energy diffused from surface A 1 that strikes directly on surface A 2 , and may be defined as 29,30  …”

“…It depends on the position and configuration of the reaching and leaving surfaces, making its calculation extremely complicated, and the results obtained are often wrong. The view factor $${F}_{12}$$ is the fraction of the radiative energy diffused from surface $${A}_{1}$$ that strikes directly on surface $${{A}}_{2}$$, and may be defined as 29,30 $$${F}_{12}=\frac{1}{\pi {A}_{1}}\mathop{\int }\limits_{{A}_{1}}\mathop{\int }\limits_{{A}_{2}}\frac{\cos {\theta }_{1}\cos {\theta }_{2}}{{r}^{2}}d{A}_{1}d{A}_{2},$$$where $$r$$ is the distance between the reaching and leaving surfaces $${A}_{2}$$ and $${A}_{1}$$, while $${\theta }_{2}$$ and $${\theta }_{1}$$ are the angles between the respective normals to $${{dA}}_{2}$$ and $${{dA}}_{1}$$ and the line $$r$$ (see Figure 3).…”