| 摘要: |
| 相变蓄冷浆体材料具有良好的流动性与高蓄冷密度，既可以充当蓄冷材料又可以作为载冷剂输送冷量。冰浆是一种安全高效的蓄冷介质，已广泛应用于蓄冷空调。然而冰浆制备温度低，限制其在空调系统中的能源利用效率。研究发现，对高质量浓度尿素溶液降温冷却可以制备尿素浆体，相变温度范围覆盖空调工况，且相变潜热较高，具有应用潜力。本文针对尿素溶液的热物性和尿素浆体的流动性能进行了实验研究，结果表明：质量浓度为43%~48%的尿素溶液的相变温度为5~12 ℃，潜热为213.7~223.2 J/g；尿素溶液（C＞32.5%）在液相线处密度随溶液质量浓度的增大而增大，运动黏度变化则相反；尿素浆体流动特性受固相率、Re的影响，不同工况下呈涨塑性流体特征。 |
| 关键词: 蓄冷浆体 尿素溶液 热物性 流动特性 |
| DOI： |
| 投稿时间：2019-09-17 修订日期：2019-12-18
|
| 基金项目:天津自然科学基金（18JCQNJC07400）资助。 |
|
| Study on Preparation and Flow Characteristics of Urea Slurry |
| Lian Lu,Zhao Yanjie,Li Zhaoning |
| (Key Laboratory of Ef?cient Utilization of Low and Medium Grade Energy, Tianjin University) |
| Abstract: |
| Phase change material slurry (PCS) can serve as cold storage material and secondary refrigerant to transport cold energy with the advantages of good flow ability and high energy density. Ice slurry is a safe and efficient cold storage medium, which has been widely used in cold storage air conditioning. However, the low temperature of ice slurry preparation limits its efficiency in terms of energy utilization in air-conditioning systems. The urea slurry can be prepared by cooling the high mass concentration urea solution, and the phase change temperature range covers the air-conditioning condition. Furthermore, the phase change latent heat is high, and thus the urea slurry can be potentially used in several applications. In this paper, the thermos-physical properties of urea solution and the fluidity of urea slurry are experimentally studied. The results indicated that the phase transition temperature of urea solution with a mass concentration of 43%–48% is 5–12 ℃,and the latent heat is in the range of 213.7–223.2 J/g. Furthermore, the density of urea solution (mass concentration was higher than 32.5%) at the liquids increased with solution mass concentration, while the tendency of kinematic viscosity was opposite. Additionally, the flow characteristics of urea slurry were affected by the solid fraction and Re; thus, it can be regarded as a dilatant fluid under different working conditions. |
| Key words: cold storage slurry urea solution thermos-physical properties flow characteristics |
