吸附效应对气相声速测量的影响

Effect of adsorption on gaseous phase speed of sound measurements

中文关键词: 气相声速  吸附效应  圆柱定程干涉法  异丁烷

英文关键词: gaseous speed of sound  adsorption  cylindrical resonator  isobutane

中文摘要:

      吸附效应是热物性实验中普遍存在的一种现象,探讨了圆柱定程干涉法气相声速测量实验中存在的两类吸附效应,并分别分析了其行成原因。归纳了低压区气相声速实验中异丁烷吸附及解吸效应产生的压力变化规律。建立了低压区吸附效应对气相声速测量影响的模型,分析了吸附效应对异丁烷气相声速测量的影响,结果表明,当吸附与解吸引起的压力变化小于10 Pa时,声速的相对变化小于1×10_-5。接近饱和蒸气压时,吸附会导致共鸣腔壳体壁面形成一层薄液膜,壳体声导纳增加,频率半宽急剧增大,而气相声速测量值呈现较大的负偏差。

英文摘要:

      Adsorption is a widespread phenomenon in thermophysical properties measurements. Two types of adsorption phenomena in gaseous phase speed of sound measurements were analyzed. The pressure variation resulting from the adsorption in the measurement of isobutane speed of sound was generalized. A model was established to analyze the effect of the adsorption on the speed of sound measurements. The results show that the impact from the adsorption or desorption on speed of sound measurements for isobutane are no more than 1×10-5 with the pressure change below 10 Pa. However, the cylindrical resonator shell will be coated with a film of condensed vapor near the saturated pressure. The specific acoustic admittance and the resonance half width increase with the adsorption. The measured speed of sound near the saturated pressure shows a large negative deviation.