环境风影响下空冷系统换热特性数值模拟

Numerical Simulation of Heat Transfer Characteristics of Air-cooled System with Ambient Wind

环境风是影响直接空冷系统运行特性的主要因素之一。以某2×300 MW直接空冷机组空冷系统为研究对象,通过数值模拟,获得了不同炉后风速下空冷岛的空气流量和热风回流率,分析了空冷岛冷却空气流动换热特性。计算结果表明:不同炉后风速对空冷岛换热特性影响差别较大;随着炉后风速的增加,直接空冷岛空气流量不断降低;热风回流率先随炉后风速增大而增加,而后随炉后风速增大而降低;空冷岛各单元热风回流现象表现出明显的区域特性,处于风场上游的空冷单元具有较大的热风回流率。

The ambient wind is one of the most important factors which affect the operation performance of the direct air - cooled system. Based on a 2 - 300 MW direct air - cooled system, the effects of different velocities of the wind from the boiler house on mass air flow and hot air recirculation flow ratio of the air - cooled island are acquired by numerical simulation. The cooling air flow and heat transfer character- istics of air - cooled island were analyzed. The results show that the operation performance of the direct air - cooled island is remarkably influenced by the velocities of the wind from the boiler house. The mass air flow of direct air - cooled island decreases with the speed of wind as the boiler house increasing. Hot air recirculation flow ratio firstly increases along with the wind speed accelerates, then it decreases in pace with the increase of the wind speed. The hot air recirculation flow ratios present conspicuous space- dependent characteristics. The upwind condenser cells generally have more disadvantageous hot air recirculation flows.