Abstract—

Low-potential solar plants, including flat-plate water-heating collectors (FSWHC), are complex systems in terms of heat engineering. A problem in the development of both stationary and non-stationary heat engineering FSWHC models is to specify convective heat exchange in SWHC channels. This paper considers the features and conditions of convective heat transfer in SWHC channels to water. It is shown that the water flow hydrodynamic and thermal stabilization sections in FSWHCs and at potential speeds of their heat carriers reach only 10 to 13 cm in length and the convective heat exchange in SWHCs can be calculated at a constant value of Nu. It is found that the differences in temperature between the walls of a SWHC channel and between the wall and the liquid will not exceed 10 and 5°C, respectively. These conditions make mixed free and forced convection in SWHC channels possible. Since the heat mainly comes from the upper walls of the channel, this determines the need for pilot studies to determine the distribution of temperature on the walls and in the liquid along the channel length and the difference in temperature between them. The heat exchange in SWHC channels can be heavily affected by free convection. An important issue when elaborating design models of heat exchange in SWHCs is the possibility of applying the convective heat exchange formulas used for plates to the walls of SWHC channels.

中文翻译：

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平板式太阳能热水收集器的对流换热特征

摘要-

就热工程而言，包括平板式集水集热器（FSWHC）在内的低潜力太阳能发电厂是复杂的系统。固定和非固定热工程FSWHC模型开发中的一个问题是指定SWHC通道中的对流热交换。本文考虑了SWHC通道中与水的对流传热的特征和条件。结果表明，FSWHCs中的水流水动力和热稳定段及其热载体的潜在速度只有10到13 cm长，并且SWHCs中的对流换热可以以恒定的Nu值计算。发现SWHC通道的壁之间以及壁与液体之间的温度差分别不会超过10℃和5℃。这些条件使SWHC通道中的自由对流和强制对流成为可能。由于热量主要来自通道的上壁，因此这就需要进行先导研究以确定沿通道长度的壁上和液体中的温度分布以及它们之间的温差。自由对流会严重影响SWHC通道中的热交换。在阐述SWHC中的热交换设计模型时，一个重要的问题是将用于平板的对流热交换公式应用于SWHC通道壁的可能性。这决定了需要进行初步研究以确定沿通道长度的壁上和液体中的温度分布以及它们之间的温差。自由对流会严重影响SWHC通道中的热交换。在阐述SWHC中的热交换设计模型时，一个重要的问题是将用于平板的对流热交换公式应用于SWHC通道壁的可能性。这决定了需要进行初步研究以确定沿通道长度在壁上和液体中的温度分布以及它们之间的温差。自由对流会严重影响SWHC通道中的热交换。在阐述SWHC中的热交换设计模型时，一个重要的问题是将用于板的对流热交换公式应用于SWHC通道壁的可能性。