Abstract A one-dimensional (1-D) transient cooling tower model is presented that can be used to simulate the start-up process of natural draft dry cooling towers (NDDCTs). The model simulates the behaviour of a NDDCT following a step increase in the heat exchanger temperature. The start-up process is analysed in two successive stages. In the first stage, the dominant mechanism is natural convection operating through generation and propagation of hot plumes rising from the heat exchanger surface. An understanding of different phases of plume development based on scaled analysis helps to predict the air flow development in this first stage. In the second stage, the air flow is driven by the draft caused by the difference in the inside and outside densities. The cooling tower system air flow development in the second stage is simulated through a quasi-steady state solution of the well-known draft equation. The simulation is repeated for three different input temperatures. The results show that the higher the input temperature, the higher is the inlet air velocity and shorter the start-up process. The results are validated against data from the commissioning tests of the University of Queensland natural draft cooling tower Gatton test rig. This study aims to help fill the knowledge gap in understanding the NDDCT start-up process. This understanding is important to the employment of NDDCTs in future thermal power plants operating in dispatchable mode.

中文翻译：

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可调度火电厂自然通风干式冷却塔的瞬态启动过程

摘要 提出了一种一维（1-D）瞬态冷却塔模型，可用于模拟自然通风干式冷却塔（NDDCT）的启动过程。该模型模拟了 NDDCT 在热交换器温度逐步升高后的行为。启动过程分两个连续阶段进行分析。在第一阶段，主要机制是通过从换热器表面上升的热羽流的产生和传播进行的自然对流。根据比例分析了解羽流发展的不同阶段有助于预测第一阶段的气流发展。在第二阶段，气流由内外密度差异引起的气流驱动。第二阶段的冷却塔系统气流发展是通过众所周知的草案方程的准稳态解来模拟的。对三个不同的输入温度重复模拟。结果表明，输入温度越高，进气速度越高，启动过程越短。结果根据昆士兰大学自然通风冷却塔 Gatton 试验台的调试测试数据进行了验证。本研究旨在帮助填补理解 NDDCT 启动过程的知识空白。这种理解对于在未来以可调度模式运行的火力发电厂中使用 NDDCT 很重要。结果表明，输入温度越高，进气速度越高，启动过程越短。结果根据昆士兰大学自然通风冷却塔 Gatton 试验台的调试测试数据进行了验证。本研究旨在帮助填补理解 NDDCT 启动过程的知识空白。这种理解对于在未来以可调度模式运行的火力发电厂中使用 NDDCT 很重要。结果表明，输入温度越高，进气速度越高，启动过程越短。结果根据昆士兰大学自然通风冷却塔 Gatton 试验台的调试测试数据进行了验证。本研究旨在帮助填补理解 NDDCT 启动过程的知识空白。这种理解对于在未来以可调度模式运行的火力发电厂中使用 NDDCT 很重要。