华北冬季密闭兔舍显热回收通风系统应用效果研究

    Application effect of sensible heat recovery ventilation system in closed rabbit house of North China in winter

    • 摘要: 针对华北地区常见围护结构的冬季不供暖密闭种兔舍保温与通风的矛盾问题,该文通过试验研究该类型兔舍不通风及运行显热回收通风系统(sensible heat recovery ventilation,SHRV)2种状态下的舍内空气质量、SHRV节能通风效果,并对比分析了SHRV结合均匀开孔送风和一端开口送风方式对舍内温度及气流分布的影响,探究SHRV在该兔舍的适用性。结果表明,相比于舍内不通风状态,运行SHRV时,舍内平均温度无显著波动;运行1 h后NH3和CO2浓度分别从9.9 mg/m3和0.23%下降到4.2 mg/ m3和0.09%,湿度从84%下降到56%适宜水平,舍内空气质量改善明显。在该地区舍外温度(6~5 ℃时,SHRV可使新风温度平均提高3.4 ℃,平均显热回收效率和能效比(coefficient of performance,COP)分别为65%和5.1,达到了国家节能标准(60%和2.5)。比较分析风管一端开口送风与管道均匀开口送风发现,均匀开口送风可使舍内平均风速降低到0.2 m/s以下,减少舍内气流和温度分层,提高送风均匀性,降低动物冷应激。研究表明,在该地区常见围护结构不供暖密闭种兔舍使用SHRV可有效缓解通风与保温的矛盾,但若要达到更理想的节能通风效果,需采取适宜的芯体片间距,增加饲养密度、加强畜舍围护结构的密闭性提高保温效果。

       

      Abstract: Abstract: The contradiction between heat preservation and ventilation usually exists in enclosed breeding rabbit houses without heating in North China during winter. The morbidity and mortality rate of young rabbits in this style barn with low feeding density increased if the temperature fluctuated greatly due to conventional ventilation. In this study, a sensible heat recovery ventilation system (SHRV) is developed to solve these problems. The air quality, energy-saving and ventilation effect of SHRV operation or without ventilation in rabbit house during daytime are studied. Meanwhile, the distribution of the temperature and airflow of SHRV with uniform openings air supply or at the end of duct in the rabbit house are compared and analyzed. An enclosed breeding rabbit house without heating rearing 315 rabbit does and 1 095 fattening rabbits was used as experimental rabbit house. The experiments were carried out from December 2015 to January 2016. Two SHRV were installed and operated from 8:00 am to 16:00 pm. The results showed that when no ventilation existed in rabbit house, the average indoor temperature was 8.91 ℃, the concentration of NH3 and CO2 increased from 7.28 mg/m3 and 0.33% to 15.02 mg/m3 and 0.33% respectively with the increase of indoor temperature, and this indoor environmental condition during daytime is harmful to the health of rabbits. No significant fluctuation of indoor temperature was found when SHRV with uniform opening air supply in the rabbit house, the average indoor temperature was 8.11 ℃, meanwhile, the concentration of NH3 and CO2 dropped from 9.91 mg/m3 and 0.23% to 4.24 mg/ m3 and 0.09% respectively after the SHRV working for 3 hours, and maintained of 4.42 mg/m3 and 0.10%, the relative humidity in rabbit house was decreased from 84% to 56%. When the outdoor temperature fluctuated within -6-5 ℃, the temperature of supply air was increased by 3.4 ℃ after passing through the heat exchanger of SHRV, the average sensible heat recovery efficiency and the coefficient of performance of SHRV were 65% and 5.1 respectively, which reached the national standard of energy-saving with the value of 60% and 2.5 respectively. Compared with air supplying at the end of duct, SHRV with uniform openings air supply will reduce the average wind speed below 0.2 m/s, the temperature difference and wind speed difference were lower than that of SHRV with uniform openings air supply. SHRV can resolve the contradiction between heat preservation and ventilation usually existed in enclosed breeding rabbit houses with common building envelope without heating in North China. At the same time, in order to achieve a more ideal energy-saving ventilation effect of SHRV in this situation, it is necessary to use appropriate plate pitch, increase feeding density and strengthen the airtightness of building envelope to improve insulation effect of houses.

       

    /

    返回文章
    返回