0 引言
1 高效能量回收器强化传热机理
Fig. 1 Schematic diagram of elliptical twisted tube structure图1 椭圆扭曲管结构示意图 |
Fig. 2 Self-supporting schematic diagram of elliptical twisted tube图2 椭圆扭曲管自支撑示意图 |
Fig. 3 Elliptical twisted tube energy recovery device model图3 椭圆扭曲管能量回收器模型 |
2 数值模拟
2.1 物理模型
Table 1 Geometric parameters of energy recovery device表1 能量回收器几何参数 |
模型编号 | A/mm | B/mm | P/mm |
---|---|---|---|
1 | — | — | — |
2 | 12.0 | 7.77 | 60 |
3 | 12.0 | 7.77 | 80 |
4 | 12.0 | 7.77 | 100 |
5 | 12.0 | 7.77 | 120 |
6 | 12.0 | 7.77 | 140 |
7 | 13.0 | 6.44 | 120 |
8 | 12.5 | 7.13 | 120 |
9 | 11.5 | 8.38 | 120 |
10 | 11.0 | 8.95 | 120 |
注:模型1为圆管模型。 |
2.2 数学模型
2.3 边界条件设置及网格划分
2.4 网格独立性验证
Fig. 4 Variation of temperature exchange efficiency with the number of grids图4 温度交换效率随网格数量的变化 |
2.5 模拟结果可靠性分析
Fig. 5 Comparison of simulation value and empirical value of Nusselt number Nu图5 努塞尔数Nu模拟值与经验值计算对比 |
3 结果与分析
3.1 强化换热效果分析
Fig. 6 Streamline distribution of shell side of energy recovery device with circular tube (a) and elliptical twisted tube (b)图6 圆管(a)和椭圆扭曲管(b)能量回收器壳程流线分布图 |
Fig. 7 Comparison of temperature changes along the tube length after air enters the shell side of two kinds of energy recovery device图7 空气进入两种能量回收器壳程后沿着管长方向上的温度变化对比 |
Fig. 8 Comparison of velocity changes along the tube length after air enters the shell side of two kinds of energy recovery device图8 空气进入两种能量回收器壳程后沿着管长方向上的速度变化对比 |
3.2 几何参数对换热性能的影响
Fig. 9 Temperature distribution characteristics of elliptical twisted tube energy recovery device under different pitches: (a) P = 60 mm; (b) P = 120 mm图9 不同螺距下椭圆扭曲管能量回收器温度分布特点:(a)P = 60 mm;(b)P = 120 mm |
Fig. 10 Variation curve of Nu of shell side with pitch图10 壳程Nu随螺距的变化曲线 |
Fig. 11 Variation curve of shell side (a) and tube side (b) pressure drop with volume flow rate under different pitches图11 不同螺距下壳程(a)和管程(b)压降随体积流量的变化曲线 |
Fig. 12 Variation curve of heat transfer coefficient K of energy recovery device with volume flow rate under different pitches图12 不同螺距下能量回收器的换热系数K随体积流量的变化曲线 |
Fig. 13 Temperature distribution characteristics of elliptical twisted tube energy recovery device with different long-short axis ratios: (a) A/B = 2.02; (b) A/B = 1.23图13 不同长短轴比时椭圆扭曲管能量回收器温度分布特点:(a)A/B = 2.02;(b)A/B = 1.23 |
Fig. 14 Variation curve of Nu of shell side with long-short axis ratio图14 壳程Nu随长短轴比的变化曲线 |
Fig. 15 Variation curve of shell side (a) and tube side (b) pressure drop with volume flow rate at different long-short axis ratios图15 不同长短轴比时壳程(a)和管程(b)压降随体积流量的变化曲线 |
Fig. 16 Variation curve of heat transfer coefficient with volume flow rate at different long-short axis ratios图16 不同长短轴比时换热系数随体积流量的变化曲线 |
4 节能性分析
Table 2 Comparison of annual energy saving benefits of ventilator energy recovery in three typical cities表2 三个典型城市的新风能量回收年节能收益对比 |
典型城市 | 总节能收益/(kW∙h) | 能量回收季节能收益/(kW∙h) | 计算节能收益总时数/h | 计算节能收益的时数比例/% |
---|---|---|---|---|
广州 | 96.57 | 191.96 | 3 750 | 42.81 |
武汉 | 523.21 | 603.50 | 4 543 | 51.86 |
北京 | 860.87 | 943.02 | 4 445 | 50.74 |