我国果蔬差压预冷方法分析

介绍了果蔬差压预冷的原理、组成、分类及影响因素,综述了近几年差压式预冷方法及设备的研究进展,提出了压差预冷技术推广的建议及今后的发展方向。     

CO2预冷双氮膨胀天然气液化工艺的海上适应性分析

优选出的CO₂预冷双氮膨胀制冷液化工艺提高了液化效率,增大了天然气液化处理能力,但其海上作业适应性还有待考察。为此,通过流程模拟和火用分析,对CO₂预冷、丙烷预冷和混合冷剂双氮膨胀制冷液化工艺流程进行了对比,并从热力学角度出发,分析了CO₂预冷双氮膨胀制冷液化工艺对原料气物性（温度、压力、组成）、流程操作参数（CO₂节流后的温度）以及CO₂纯度的敏感性,对其海上适应性做出了评价。结论认为：该工艺可适用于海况恶劣的环境,其对原料气温度、压力和组成变化不敏感,适合于中到大规模的天然气液化生产。最后,为保证流程的安全、高效运行,提出了该工艺应用中需注意的3个问题：①压缩机水冷器温度应低于31.1 ℃;②CO₂预冷温度应超过-53 ℃;③CO₂杂质含量应控制在1%以内。     

两套25000m~3/h空分设备的优化操作和改进

为提高25000 m3/h空分设备的运行稳定性和经济性,对空分设备的氮水预冷系统、精馏系统以及配套的液化装置实施了优化操作与改进措施。详细分析了优化操作的理论依据、具体的实施方案和效果。     

空气预冷系统设计中的某些认识误区与优化设计

分析空气预冷系统设计中容易产生的某些认识误区,阐述优化设计的重要性,即在满足用户要求的条件下,对空气预冷系统的设计尽可能做到高效、经济、合理。     

果蔬真空预冷技术及其应用分析

在介绍真空预冷技术原理的基础上,详细阐述了该技术的特点,分析了真空预冷技术应用过程中需要注意的问题,以便于真空预冷技术的进一步研究和推广.     

Process parameters for hydrocooling apricots, plums, and peaches

Freshly harvested apricots, plums, and peaches in crates containing 5–20kg were hydrocooled in flowing water at 1°C and 50mms^-1. The cooling parameters: lag factor, cooling coefficient, and time to half-cool, determined from the exponential decline in the dimensionless ratio of temperature differences between fruit centre and coolant temperature at time t and at zero time, varied somewhat with crate load. Increasing the load from 5 to 20kg increased the time to half-cool apricots by 17% and plums and peaches by 39%.     

Producing high quality hardened parts using sequential hard turning and ball burnishing operations

This paper presents a novel sequential process which incorporates optionally CBN turning operations with (CHT) or without (HT) cryogenic pre-cooling of the workpiece and ball burnishing (B) operations. The main hypothesis tested concerns the fact that cryogenic pre-cooling slightly deteriorates surface finish but at the same time it enhances the mechanical and service properties of the subsurface layer without white layer. Moreover, it indicates how this complex process (cryogenic pre-cooling, hard turning and ball burnishing) should be performed to obtain satisfactory surface integrity and service properties. Investigations include 2D and 3D surface roughness, microstructure alterations by means of SEM/BSE techniques and microhardness distribution. The geometrical, mechanical and physical improvements of surface layer properties were revealed.     

微型冷库内送风方式与果蔬预冷的研究

通过测试，得出了在单一风机、一拖二风机及夹套式三种不同送风方式下的90m^3微型冷库内离地面1．5m处的温度场分布。结果表明，夹套式送风方式的微型预冷库具有最好的温度场分布。根据实验结果建立了果蔬预冷时温度降速率、压力降速率及温度变化率的相关耦合式，提出了在夹套式库内的最佳预冷风速。     

空气预冷系统高压水泵变频改造分析与应用

23500 m3/h空分设备空气预冷系统的4台高压水泵为全负荷定速运行泵,其水流量超过了空气预冷系统的实际需求量,因此运行中出现了高压水泵出口节流现象,造成电能浪费。为了节能降耗,对4台高压水泵进行了变频改造。分析了高压水泵变频改造的必要性和改造后的运行优势,阐述变频改造后存在的各种问题及解决措施,最后分析了改造的经济效益。     

节能技术在空分设备空气预冷系统中的应用

从空气预冷系统的流程形式、静设备(空冷塔、水冷塔)及动设备(水泵、制冷机组)三个方面,结合节能理论和具体实践探讨了空气预冷系统的节能技术和效果。