商用制冰机的性能研究

主要介绍商用风冷制冰机的工作原理,并通过试验研究影响商用制冰机性能指标的主要因素,验证环境温度和水温变化对制冰机的制冰时间和收冰时间影响较大,制冰时间长短决定制冰机的产冰量、耗电量、耗水量等,其中环境温度对制冰时间影响最大,对制冰机的影响最为显著.     

利用自然冷源单管制冷蓄冷试验和一维传热模型

通过对利用自然冷源单管制冰过程的传热分析,建立了管制冰的一维传热模型,在蓄冰池围护为绝热条件下,用积分法对一维模型进行了求解;在模拟自然冷源制冰实验台进行的单管制冰试验表明：管道制冰半径与制冰时间呈幂函数关系,一维传热模型解析解的计算结果是可靠的。     

基于模块化过冷解除的冰浆制取系统实验研究

过冷水法动态冰浆制取技术具有传热效率高、系统简单等优点,但过冷却器易发生冰堵是影响其稳定性的突出问题。本文提出一种基于模块化过冷解除装置的动态制冰系统,利用设置在过冷却器内的可灵活拆装式螺旋叶片对制冰溶液进行过冷解除,同时刮削换热壁面上粘附的冰晶。测试了不同工况下该制冰系统的性能,结果表明该制冰系统可稳定产出冰浆并有效改善冰堵问题,最高含冰率达9.1%,最大持续制冰时间可达521 s。冰浆含冰率与持续制冰时间成正比。NaCl添加剂质量分数为6%时对冰浆含冰率和持续制冰时间的改善效果显著。实验获得制冰系统最佳运行参数:制冰溶液体积流量为0.50 m^3/h、二次冷媒起始温度为-15℃、螺旋叶片转速为175~225 r/min。     

过冷却水制冰蓄冷性能的实验研究

利用过冷却水制冰蓄冷的关键设备是过冷却器，建立了过冷却器制冰蓄冷的实验装置。通过测定过冷却器进、出口两种流体的温度，整理绘制出正常状态下温度随时间的变化曲线。实验得出，当冷水温度为-1．5℃-1．7℃，流速在1．4-1．8m/s时，经管束喷出的水流会在碰撞后成冰，有利于制冰蓄冷，可得到较高的HPF值。     

使用替代工质HFC134a的家用冰箱动态模拟及实验研究

本文以使用替代工质ＨＦＣ１３４ａ的家用冰箱为研究对象，从基本的连续、动量、能量方程出发，引入两相流的压降算法，建立了冰箱制冷系统的动态分布参数模型。利用所建模型，对家用冰箱的动态开机过程进行了模拟计算；并对同一过程进行了实验研究，数值计算结果与实验吻合良好，证明了模型的可靠性。依照国标做了大量实验，检测了冰箱性能，并进行充灌量实验。     

冰箱用R134_a温度分布及变化规律的实验研究

实验测定了BCD-185(ST)型家用冰箱在环境温度为18℃与38℃时冷藏室和冷冻室温度分布及变化情况,同时还测定了环境温度(38℃)稍有上升时(1℃)冷冻室,冷藏室温度变化的情况,从而得出贮藏温度变化的规律。     

过冷水连续制冰系统中过冷却器进出口水温的选择

为了使给定的过冷水连续制冰系统的制冰功率和COP达到较高的数值，关键在于过冷却器进出口水温的选择。在过冷水连续制冰系统中，从蓄冰槽出口到过冷却进口水的温升可以通过三种不同途径实现，(1)专门外界热源加热；(2)依靠环境传热；(3)空调系统回水加热。研究了在这三种情况下过冷水连续制冰系统过冷却器进出口水温的选择方法。计算了某一给定系统在这三种情况下的制冰功率和COP随过冷却器进出口水温的变化，根据计算结果选择了在这三种情况下合适的过冷却器进出口水温。     

片冰机蒸发器的工程传热模型研究

对片冰机蒸发器的传热特点进行了分析,在一定简化基础上,建立了片冰机蒸发器的工程传热模型,得到了制冰时间、制冰厚度、蒸发温度、进水温度、结冰筒材料与壁厚等几个工程应用中的重要参数间的关联式。用该关联式预测的制冰时间与试验结果吻合良好,所建传热模型对片冰机的优化设计有指导意义。     

“双碳”背景下制冰新技术研究进展

目的 总结“双碳”背景下制冰新技术的研究进展，为研发更加低碳高效的制冰技术提供参考。方法 重点对二氧化碳跨临界制冰技术、真空闪蒸制冰技术和太阳能吸附式制冰技术3种制冰新技术的研究进展进行综述。结论 二氧化碳跨临界制冰技术、真空闪蒸制冰技术和太阳能吸附式制冰技术具有低碳、节能等优点，可对冷链运输、人工冰场等领域起到积极作用，在“双碳”背景下具有较好的应用前景。在此基础上，如何保证制冰系统稳定性、提高制冰效率是未来主要的研究方向。     

上浮式动态蓄冷装置制冰过程的实验研究

对片冰上浮式蓄冷装置的制冰过程进行了实验研究,考察了片冰平均厚度、蒸发温度随时间的变化关系,并测算了蓄冰槽的充填率脚。研究结果表明制冰装置具有蒸发温度高、热经济好、蓄冰槽空间利用率高的优点,它适用于冰蓄冷空调系统。     

充冷过程中冷板内特性研究

针对机械冷板冷藏车冷板充冷时间长的问题,根据热量守恒原理建立了冷板内共晶冰冻结过程的数学模型,并对影响冷板充冷过程的关键因素进行了讨论,用准静态方法对蒸发盘管外共晶冰的形成过程进行了数值计算.计算结果表明,随着盘管周围共晶冰厚度的增加,共晶冰冻结缓慢;降低蒸发温度,减少冷板外热负荷,可以明显减少共晶冰的冻结时间;冻结过程中,冷板内的逐时蓄冷量基本不变.     

蓄冷平板堆积床动态蓄冷性能研究

本文建立了描述蓄冷平板堆积床动态蓄冷性能的数理模型,并与实验结果进行了比较,两者吻合得较好。分析了载冷剂流量对充冷时间的影响,得到了载冷剂出口温度和蓄冷剂温度随时间的变化规律。该模型可为蓄冷平板堆积床的设计和优化提供依据     

新型流态冰蒸发制冷循环及制冰量性能分析

介绍了蒸发过冷水制冰原理及系统流程,分析了相应的蒸发制冷循环,对单位质量(1k)干空气制冰量性能及影响因素进行了研究并建立了相关数学模型,计算结果显示,水的初始温度越高单位质量干空气制冰量越低,而单位质量干空气制冰量相同时水温越高对应的蒸发水量则越大,同时随着空气出口相对湿度增大,单位质量干空气制冰量也随之增加.另外,...     

螺旋藻细胞冷冻过程微尺度传热传质特性

为了探索保持螺旋藻活性的最佳冷冻条件,研究了冷冻过程凝固界面和螺旋藻细胞之间相互作用的物理现象,在考虑细胞和冰界面之间的耦合传热传质、膜的传输特性和凝固界面的移动过程的情况下,建立了螺旋藻细胞冷冻过程冰界面与细胞之间相互作用的数学模型,检查了螺旋藻细胞被冰界面包围过程的温度场和浓度场,研究了螺旋藻细胞被冰界面包围过程中细胞体积的收缩情况及影响因素.计算结果表明,膜的渗透性和冷却速率是影响细胞体积收缩的主要因素.该模型可优化减小螺旋藻细胞损伤的最佳冷冻条件.     

A two-dimensional frost-heave model for buried pipelines

The rigid-ice model of frost heave is one of the most comprehensive frost-heave models but is restricted to one-dimensional cases in its present form. In this paper, the model is extended to two-dimensional problems. The complete formulation of the partial differential equations governing heat, moisture and ice transport in freezing soils is provided. The equations are subsequently solved using the Galerkin finite element method in space and the finite difference method in time. A computer program is developed for the two-dimensional rigid-ice model. A case of freezing around chilled gas pipeline is solved and the numerical results are compared with experimental values, with good agreement between the two sets of results.     

Rapid Solidification Process of a Water Droplet Due to Depressurization

This paper reports an experimental and numerical study of rapid solidification of a water droplet due to depressurization. During the experiment, a distilled water droplet was suspended on a thermocouple, which was also used to measure the droplet temperature, and the droplet surface temperature was captured by an infrared thermograph. The experimentally measured data indicates that freezing occurs from the droplet surface when the droplet temperature reaches a certain subcooling. A mathematical model was constructed to simulate the temperature transition and the temperature distribution within the sphere. The model considers the pressure reduction in the test vessel, the kinetic condition for undercooled solidification, and the heat transfers due to convection and sublimation at the ice surface. A coordinate transformation method was used to capture the two moving boundaries within the droplet, which are internal solidification interface and surface sublimation interface. The model-predictions agree well with the measured temperature data, demonstrating the soundness of the present model. The results show that the rapid solidification of a water droplet due to depressurization is a typical non-equilibrium phase transition, with a lower ambient pressure, the solidification speed will be faster, and the duration time for droplet center temperature keeps constant will be shorter.     

Study on continuous ice slurry formation using functional fluid for ice storage – Discussion of optimal operating conditions

A functional fluid was made by adding a small amount of additive to a water–silicone-oil mixture with 90 vol% water content, and the functional fluid was transformed into an ice slurry by cooling while stirring. The new ice formation system, which authors proposed for ice storage based on the results of previous studies, demonstrated that the ice slurry could be formed continuously for 10 h. In the current paper, experiments were carried out, varying operating conditions, and an optimal operating condition was determined to improve performance of the present system still more. From the experimental results, the conditions necessary to increase the amount of recovery ice were clarified. The time-dependencies of the shape and size of formed ice particles were also shown. Moreover, the reason why the freezing temperature of the functional fluid rose due to repetition of ice formation was clarified, and its measure was discussed. The present study then found that it was possible to form and recover a larger amount of ice than in previous attempts, given the rise in freezing temperature.     

液氮冻制冰套法对水三相点温度的影响

介绍了液氮作为冷却剂在水三相点容器内冻制冰套的方法。利用该方法同时在两个不同真空度的水三相点容器内分别冻制冰套。通过实验，研究了此方法对所复现的水三相点温度的影响。实验结果表明：冻制过程中产生的应力以及开始生成的小冰晶引起水三相点温度偏低；并且，其对水三相点温度的影响随着水三相点容器内真空度的降低而增大。随着应力慢慢消除，小冰晶逐渐长大为大冰晶，所复现的水三相点值逐渐回升并趋于稳定。因此，为了高精度复现和准确测量水三相点，采用该冻制方法时，必须将冰套老化至少5天以后，才可以消除其对水三相点温度的影响。     

Yearly simulation of the interaction between an ice rink and its refrigeration system: A case study

A transient model of airflow and heat transfer in an indoor ice rink and a quasi-steady model of its refrigeration system have been coupled and used to simulate their response to the time dependent ambient conditions and operating schedule for a typical meteorological year. The results for two different cases show that it is possible to reduce significantly the time of operation of the compressors and the energy consumption of the refrigeration system by simultaneously reducing the ceiling emissivity and increasing the secondary coolant temperature without affecting the quality of the ice.