变频空气源热泵供暖结霜图谱

Frosting map of variable-frequency air-source heat pump for building space heating

变频空气源热泵用于建筑供暖时,其转速根据热负荷的变化而调节,改变室外盘管表面与空气的温差,进而影响结霜,使其结霜特性与定频空气源热泵有较大差异。为揭示变频空气源热泵因负荷控制方法不同而导致的结霜差异,本文通过实验建立了变频空气源热泵在严寒地区的结霜图谱,并进一步通过数值模型绘制了实验机组在寒冷地区和夏热冬冷地区供暖运行的结霜图谱,定量研究了热负荷调节对结霜特性的影响。结果表明:变频空气源热泵的结霜临界相对湿度的变化与定频空气源热泵完全相反,其随着室外温度的降低而下降;同一台热泵机组在不同地区供暖时,供暖室外计算温度越低,结霜临界相对湿度越高,同时结霜区域的上下限温度越低;变频空气源热泵机组在哈尔滨、北京和上海供暖时的结霜区域温/湿度范围分别为-26.5~1.0℃/63%~81%、-18.3~3.2℃/59%~72%、-10.1~5.0℃/53%~63%;而当变频机组运行在最高频率后,其结霜表现出与定频机组相同的趋势。

When the variable-frequency air-source heat pump(VFASHP)is used for building space heating,its compressor speed is regulated based on the heating load,which changes the temperature difference between the outdoor coil surface and the air,thus affecting the frosting,making its frosting characteristics significantly different from the constant-frequency air-source heat pump(CFASHP).To reveal the frosting difference of VFASHP caused by different load control methods,this paper establishes the frosting map of VFASHP in severe cold zone through experiments,further draws the frosting map of experimental units in cold zone and hot summer and cold winter zone through numerical models,and quantitatively studies the influence of heating load regulation on frosting characteristics.The results show that the change of frosting critical relative humidity of VFASHP is completely opposite to that of CFASHP,which decreases with the decrease of outdoor air temperature.When the same unit is applied to different areas for space heating,the lower the outdoor calculated temperature for heating is,the higher the frosting critical relative humidity is,and the lower the upper and lower limit temperature of the frosting area is.The temperature and relative humidity range of the frosting area for heating by the unit in Harbin,Beijing and Shanghai are-26.51.0℃/63%81%,-18.33.2℃/59%72%and-10.15.0℃/53%63%,respectively.However,when VFASHP operates at the highest frequency,its frosting shows the same trend as CFASHP.