畜舍热交换芯体-风机热回收通风系统的热回收效果

Heat recovery effect of heat recovery ventilation system with heat exchanger-fan for livestock house

热回收通风作为一种节能的通风换气方式,可缓解畜舍保温能耗与通风的矛盾。然而民用一体式热回收通风系统在畜舍中直接应用时存在通风量小、单位通风量的设备造价高等问题。该研究设计了适用于畜舍的新型节能热回收通风系统,并研究该热回收通风系统在以下3种不同配置条件下的热回收效果,探究该系统在畜舍中的较佳运行条件:板翅式热交换芯体配置不同迎面风速的热回收效果;新风依次经过2个串联连接的板翅式热交换芯体后的热回收效果;优化了板式热交换芯体与噪声小、风量大的轴流风机的参数配比后的热回收效果。结果表明:在舍内外温差为12.08℃,芯体配置迎面风速分别为1.05和0.86 m/s时,新风温度经过板翅式热交换芯体后分别升高了1.93和2.79℃,显热回收效率、热回收负荷和能效比分别为35.88%和43.63%、0.16和0.19 kW,1.37和1.61,两者显热回收效率均未达到冬季65%的节能标准。在舍内外温差为10.49℃时,新风依次经过串联的2个板翅式热回收芯体,经过第1次热交换后新风温度升高2.59℃,显热回收效率为52.11%,热回收负荷及能效比分别为0.39 kW,3.26;新风经过第2次热交换芯体时热回收作用甚微。优化板式热交换芯体与风机配比后,在舍内外温差为12.12℃,迎面风速为4 m/s时,新风温度升高8.23℃,显热回收效率为69.9%,能效比为8.0,达到了冬季节能标准。从该研究热回收效果看,第3种配置参数条件平衡了热回收效率及通风需求的关系,可满足畜舍大通风量及节能的需求。

Heat recovery ventilation, as a kind of energy saving ventilation, can alleviate the contradiction between heating energy consumption and ventilation. The application of heat recovery ventilation system for residential buildings has turned out that it has the problems of low ventilation efficiency and high cost when applied in the livestock house. A modified heat recovery ventilation system for livestock house was designed in this study, and the efficiency of heat recovery ventilation equipment under 3 different operating conditions was tested to find out the optimal operation conditions. In the first operating condition, the temperature difference inside and outside the livestock house was 12.08 ℃. The size of plate-fin heat exchanger was 500 mm× 500 mm×250 mm. Fresh air supply adopted a positive pressure way and exhaust air used a negative pressure way. When the approach velocities were 1.05 and 0.86 m/s, the fresh air temperature through the heat exchanger increased by 1.93 and 2.79 ℃, the sensible heat recovery efficiency was 35.88% and 43.63%, the heat recovery load was 0.16 and 0.19 kW, and the coefficient of performance was 1.37 and 1.61, respectively. The sensible heat efficiency under both approach velocities was far below the energy saving standard in winter （〉165%）. In the second operating condition, 2 plate-fin heat exchangers were in cascade connection, and the fresh air went through the 2 plate-fin heat exchangers in sequence. The size of heat exchanger, fan type and ventilation pattem were the same with the first condition. In this way, when the temperature difference between inside and outside was 10.49 ℃, the fresh air temperature passing through the first heat exchanger increased by 2.59 ℃. The sensible heat recovery efficiency was 52.11%, and meanwhile the heat recovery load and the coefficient of performance were respectively 0.39 kW and 3.26. The poor performance of the second heat exchanger showed that the two heat exchangers in series for livestock house were unnecessary. In the third configuration condition, both matching parameters and connection ways between heat exchanger and fans were optimized. The plate heat exchanger and the axial flow fan with low noise and large volume were used. The heat exchanger size was 600 mm × 600 mm × 600 mm. Both fresh air supply and exhaust air used a negative pressure way. When the temperature difference between inside and outside was 12.12 ℃ and the approach velocity was 4 m/s, the fresh air temperature increased by 8.23 ℃. The sensible heat recovery efficiency was 69.9%, and the coefficient of performance was 8.0, meeting the national energy-saving standard requirement. It is concluded that the heat recovery ventilation aimed to improve the balance between heat recovery efficiency and ventilation efficiency can meet the requirement of large volume ventilation and energy saving in the livestock house. So it is of great value to optimize the parameter and structure of heat recovery ventilation system for livestock house.