Abstract A novel procedure for transient numerical modeling of solar stills is proposed in this study. With no need to specify the glass and water temperatures as boundary conditions, instantaneous weather and irradiance data are the only inputs in the present CFD simulation. The absorption of solar radiation and radiative heat transfer in different components of the solar still are accounted by solving the DO radiative transfer equation. Instead of applying costly multi-phase techniques, species equation for water vapor is solved by coupling with energy equation through user defined functions. In this method, the latent heat of evaporation/condensation is considered as a sink/source term in the energy equation. The required evaporation and condensation rates are calculated by integrating Fick's law on the water and glass surfaces. The latent heat of phase change is assumed to be shared between the two neighboring bodies by introducing a coefficient α with the appropriate value of 0.5. Therefore, transient temperature and concentration distributions and productivity in passive and active solar stills are calculated throughout a day with moderate computational cost. By applying the present method to multi-stage active solar stills, it is shown that increasing the number of stages beyond six is not beneficial.

中文翻译：

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盆地太阳能蒸馏器瞬态 CFD 建模的新程序：物种和能量方程的耦合

摘要 本研究提出了一种新的太阳能蒸馏器瞬态数值模拟方法。无需指定玻璃温度和水温作为边界条件，瞬时天气和辐照度数据是当前 CFD 模拟的唯一输入。通过求解 DO 辐射传递方程来计算太阳能蒸馏器不同组件对太阳辐射的吸收和辐射传热。不是应用昂贵的多相技术，而是通过用户定义的函数与能量方程耦合来求解水蒸气的物种方程。在该方法中，蒸发/冷凝的潜热被视为能量方程中的汇/源项。所需的蒸发和冷凝速率是通过在水和玻璃表面上积分 Fick 定律来计算的。通过引入适当值为 0.5 的系数 α，假设相变潜热在两个相邻物体之间共享。因此，被动式和主动式太阳能蒸馏器的瞬态温度和浓度分布以及生产率是全天计算的，计算成本适中。通过将本方法应用于多级主动式太阳能蒸馏器，表明将级数增加到超过六级是不利的。