非设计工况下水蒸气喷射制冷系统热工性能分析

Thermal Performance Analysis of Steam Jet Refrigeration System under Non Design Conditions

水蒸气喷射制冷系统作为一种环境友好型系统,可利用低品位工业余热或太阳能作为驱动热源。建立了水蒸气喷射制冷系统及其主要部件的热力学模型,对设计工况(发生温度140℃、蒸发温度10℃、冷凝温度26℃)及非设计工况下的喷射器喷射系数、系统COP及系统制冷量进行研究。发现,发生温度由130℃升高到150℃,系统制冷量呈上升趋势,喷射系数、系统COP呈先上升后下降的趋势,二者在设计工况下达到最大值;而随着蒸发温度的升高,三者均呈现不断上升的趋势,其中,蒸发温度由2℃升高到22℃,喷射系数增长了约0.6倍;冷凝温度存在一个临界值,在临界值前,喷射系数、系统COP及制冷量几乎不受冷凝温度的影响,当超过临界值时,三者会迅速下降。且随着发生温度的升高,该临界值随之增大,发生温度从120℃升至140℃,其对应临界值分别从20℃升至24℃。

As an environment-friendly system,the steam jet refrigeration system can use low grade industrial waste heat or solar energy as driving heat source,which has attracted extensive attention of researchers.In this paper,the thermodynamic process of steam jet refrigeration system is analyzed,the thermodynamic model of the system and its main components is established.The ejector injection coefficient,the coefficient of performance of the system and the system cooling capacity under design conditions(generation temperature 140℃,evaporation temperature 10℃,condensation temperature 26℃)and non-design conditions are studied.It is found that with the generation temperature increasing from 130℃to 150℃,the cooling capacity of the system increases.The injection coefficient and the coefficient of performance of the system first rises and then declines.They reach the maximum under the design conditions;with the increase of evaporation temperature,they all increases.The evaporation temperature increased from 2℃to 22℃,and the injection coefficient increased by about 0.6 times;There is a critical point for the condensation temperature.With the generation temperature increasing,the injection coefficient,the coefficient of performance of the system and the refrigeration capacity are almost constant when the condensation temperature is lower than the critical point.Otherwise,they decrease rapidly when the condensation temperature exceeds the critical point.Besides,with the generation temperature increasing,the critical value increases.The generation temperature rises from 120℃to 140℃,and the corresponding critical points rise from 20℃to 24℃respectively.