低温冷库的温度要求与能效分级探讨

冷冻食品在低温冷库中贮藏是食品冷链中的重要环节,低温冷库的库温不均匀度、库温波动对货品品质有非常重要的影响。在保证正确的库温、合理的库内温度不均匀度和库温波动范围的前提下,对冷库能耗进行评价才有意义。制订低温冷库温度要求和对低温冷库的能效进行分级,将在规范低温冷库的设计和建设,提高冷库的货品品质,保证食品安全,降低冷库能耗,提高冷库的综合效益等方面发挥积极的作用。     

水蒸气迁移与冷库建筑

冷库是低温建筑,在冷库运行中,库内外始终存在着温度差异。因此,水蒸气必然从高温侧向低温侧迁移扩散。我国除高纬度地区外总的规律和趋势是库外向库内迁移扩散。水蒸气迁移过程必然导致隔热体因受潮而使隔热性能下降,增加冷库耗能。     

高温库改造成为气调冷库的实例探讨

本文介绍了厦门某食品公司的高温冷藏库改造成气调库的工艺设计实例。对高温库改造成气调冷库和直接建造气调库的异同进行分析比较。在对该具体实例进行设计调研和费用计算基础上，对一般高温库改造为气调库的典型问题，包括库房结构，制冷设备、气调系统选择和气调方式确定等进行了分析探讨。提出了高温库改造为气调库时注意的问题，对于非大宗短期贮藏、多品种、多批量的情况，柔性气调库方式的经济效益尤其明显，建议推广应用。     

氨系统超高单层节能低温冷藏库研制报告

该文对超高单层低温冷藏库的建筑结构、冷却设备合理分配、制冷系统的动态平衡的运行进行了实际工程分析。超高单层低温冷藏库库温波动小，结霜少，在动态平衡下连续运行具有较大节能效果，并且在提高冷库建筑土地利用率方面具有重要意义。这对低温冷藏库的节能建设和进一步提高藏品质量将发挥重要作用。     

低温冷风机热气融霜实验研究

简述了低温冷库冷风机的热气融霜方式,对一座低温实验冷库进行了热气融霜实验.研究了在不同库温情况下的融霜过程,从库温、凝水量、温度场变化以及制冷系统运行状况等方面,分析了热气融霜对低温冷库的影响.实验结果表明热气融霜具有时间短、对库温影响较小等优点.     

低温冷库冷风机的变频节能研究

分析风机变频调速的节能原理。通过低温冷库蒸发器风机在不同工作库温下的变频试验研究,表明风机采用变频调速控制运行后,不仅功耗降低,系统的有效制冷量明显增加,且库温越低增益越大,对于提高经济效益和节约能源有重要意义。     

冷库软木隔热层施工事故实

一、现场情况检查这是一座新建的300吨冷库(冷库平面示意于图1),该库为钢筋混凝土框架结构共二层,第一层属高温库,分两间总库容量为100吨,第二层属低温库为一大间设计库容量为200吨,冷库隔热材料全部采用软木,高温间墙体软木为150mm 厚;低温间墙体软木为200mm 厚,防潮层采用二布三油(即二层玻璃布,三层塑料防水油膏),围护结构如图2所示,围护结构的保温防潮层施工时间在7月份。该库软木墙体的防潮层做好的第三天就发现二楼东北墙软木局部开始起鼓,约经15天我们对该库隔热墙体进行检查时发现,二     

低温冷库电热融霜与热气融霜的对比试验研究

对低温实验冷库进行了电热融霜和热气融霜实验.阐述在不同库温情况下两种融霜方式的实验过程,从融霜阶段库内温度场变化、系统耗能等角度,分析了两种融霜方式的优劣,得出:热气融霜较电热融霜明显地具有对库内温度场影响小、耗能低的突出优点,并且库温越低,优越性越显著.实验为低温冷库的融霜研究提供了有效依据.     

小型氨库改造中的常见故障分析

对小型氨库改造中常见问题进行分析，给出冷库管道及排空气系统的改造措施，阐述解决冷库高能耗、低效率等问题的方法。     

装配式速冻库的冻结性能测定及分析

一、前言 改革开放以来,我国各地引进了不少装配式冷库生产线,形成了一定的生产规模,广东省就有数条,分布在广州、东莞、佛山、三水等地。与传统土建冷库相比,装配式冷库由于库体是由工业化成批生产的预制板装配而成,因此具有建库速度快、结构紧凑、占地面积小、重量轻、成套性好、灵活性强等特点,在国内外已大量应用于食品的冷冻和冷藏。 目前国内应用的装配式冷库大多为高温冷藏库和低温冷藏库,装配式速冻库则比较少用。     

含高热密度机柜的IT机房空调的节能措施

如今设有高热密度机柜的IT机房越来越多,传统机房空调设计中存在着使这种机房空调能耗增加的误区,即单纯追求机房内的环境温度,而忽略了如何有效地带走每台高热密度机柜的散热量这一核心问题。本文针对此问题,总结如下4个简单易行的节能措施:当单个服务器容量超过5kW时,可采用冷气流或热气流通道封闭;当单个服务器容量超过8kW时,可采用行级制冷或机柜级制冷;当高热密度机柜和普通机柜并存时,应均匀分布高热密度机柜;合理布局机房空调。     

An assessment of the integration of nurse timetable changes with operating room planning and scheduling

The objective of this paper is to understand the links between the management of operating rooms and nurses, and to investigate the trade-offs between the number of operating rooms used, nurses used and overtime work. To do so, we proposed a model that plans and schedules surgical interventions in the operating rooms while considering the availabilities of surgeons and anesthesiologists; the model also includes or discards nurse scheduling. The flexible modeling approach allows us to compare different alternatives, each one representing a different scenario of managing the operating rooms at an operational level. The scenarios were applied to two data-sets and compared on the basis of performance indicators, which include operating costs, utilisation rates of nurses and number of overtime hours done. The important findings were that there is no relationship between the number of nurses required and the number of operating rooms used; the simultaneous scheduling of nurses and surgical interventions provided a better resource usage, a higher occupation rate of nurses, less overtime and furthermore, operating costs were lowered by at least 10% on average.     

分离型二级脉管制冷机的实验研究--Ⅱ:液氦温区二级脉管制冷机

研制1台新型液氦温区分离型二级脉管制冷机,该制冷机由2台独立的脉管制冷机组成,一级回热器冷端和二级回热器中部通过热桥相连,从根本上弥补了传统直接耦合型多级脉管制冷机级间干扰的不足.采用双压缩机双旋转阀驱动该二级脉管制冷机,第二级最低温度达到了2.5 K,在4.2 K下有508 mW制冷量,同时一级在37.5 K有15 W制冷量.第二级充气压力由1.7 MPa增大到1.85 MPa,制冷机在4.2 K下的制冷量可以达到590 mW.为了能简化结构、扩大应用,提出采用单压缩机单旋转阀驱动该分离型脉管制冷机,达到了相同的制冷性能.     

山东省果蔬冷库技术状况剖析

根据对山东果蔬冷库问卷调查的反馈,对80份有效问卷进行统计分析。发现山东果蔬冷库的技术水平偏低,仅5％的冷库采用自动控制,基本采用活塞式压缩机。制冷系统的管理十分薄弱,50％左右的冷库缺乏专业人员。有1／4的问卷没有反馈全年的电费和用电量。对于相同库容量的冷库,全年电耗差别可达3倍以上,反映出山东果蔬冷库的节能有巨大的潜力。     

抗爆控制室空调系统设计

抗爆控制室是石油化工厂的核心建筑，空调系统实现重要房间恒温恒湿，维持各房间的梯度正压值，减轻室外空气对仪表的腐蚀，对控制室的正常运作起着重要作用。本文在对空调系统划分方法、房间送风量的确定、气流组织及压力平衡、抗爆措施和控制联锁等方面进行深入探讨和研究的基础上，对常规抗爆控制室空调系统的优缺点进行归纳。     

Nitrogen, methane, and ethane sorption on activated carbon

Joule–Thomson (JT) sorption cryocoolers rely on sorption compressors that provide a continuous flow with predetermined high and low pressures without any vibration emission. These cryocoolers may operate with different fluids, in accordance with the desired cold temperature. Nitrogen, methane, and ethane are prevalent candidate fluids for sorption cryocoolers, providing cold temperatures of about 80 K, 120 K, and 185 K, respectively. In order to develop a sorption compressor it is necessary to know the sorption characteristics of the fluid on the selected adsorbent. In this work we present experimental sorption measurements of the mentioned fluids on a commercial pelleted activated carbon. The Langmuir, Freundlich, and Sips models are fitted to the experimental results and further modified to incorporate the temperature dependence, in order to extend the prediction of sorption properties into wider ranges of temperature and pressure. It appears that each fluid has a different model that best fits its characteristics. Finally, the isosteric heat of adsorption is calculated for the three mentioned fluids as a function of the adsorption coverage and polynomial regressions are obtained for it.     

Experimental study on the coupling characteristics of 100 Hz inertance tube pulse tube cryocooler working under optimal frequcency

Miniature pulse tube cryocooler is one of the main developing trends of pulse tube cryocooler. Four pulse tube cold fingers, two compressors and a series of inerance tube assemblies are employed to carry out the experimental investigation of coupling characteristic of miniature pulse tube cryocooler. It is concluded that the cooling performance of miniature pulse tube cryocooler is determined by the match conditions among its compressor, cold finger and inertance tube. If the three parts of cooler match well, the cold finger can achieve nearly same cooling performance under two totally different working conditions.     

Modelling of reciprocating and scroll compressors

This paper presents simple and thermodynamically realistic models of two types of compressors widely used in domestic heat pumps (reciprocating and scroll compressors). These models calculate the mass flow rate of refrigerant and the power consumption from the knowledge of operating conditions and parameters. Some of these parameters may be found in the technical datasheets of compressors whereas others are determined in such a way that the calculated mass flow rate and electrical power match those given in these datasheets.The two models have been tested on five reciprocating compressors and five scroll compressors. This study has been limited to compressors with a maximum electrical power of 10 kW and for the following operating conditions: evaporating temperatures ranging from −20 to 15 °C and condensing temperatures ranging from 15 to 60 °C.The average discrepancies on mass flow rate and power for reciprocating compressors are 1.10 and 1.69% (for different refrigerants: R134a, R404A, R22, R12 and R407C). For scroll compressors, the average discrepancies on mass flow rate and power are 2.42 and 1.04% (for different refrigerants: R134a, R404A, R407C and R22).     

考虑摩擦功率的双级压缩制冷系统最佳温度的确定

以氨双级压缩制冷循环为例,在确定最佳中间温度时,考虑实际制冷循环中的摩擦因素;以实际制冷系数的最大值为依据,经过计算与分析提出了最佳中间温度又一经验计算式,并分析了其计算结果的误差范围.