氨活塞式双级制冷压缩机运行特性数学模型

本文根据生产厂家提供的氨活塞式制冷压缩机在标准工况下运行特性参数，应用微机推导计算出各种氨双级制冷压缩机在实际运行工况下，制冷量随蒸发温度和冷凝温度变化的关系数据，绘制成一系列产品性能特性曲线图。在保证数值计算精度的前提下，采用最小二乘法多变量数据拟合出各种氨活塞式双级制冷压缩机运行特性数学模型。     

基于变容积比三缸双级压缩补气增焓技术的家用空气源热泵制热性能分析

在低环境温度工况下，传统空气源热泵存在制热量不足、制热性能系数(COP)低等问题，这导致其热舒适性差和运行经济性差，阻碍了空气源热泵技术在北方寒冷地区的应用。本文将变容积比三缸双级压缩补气增焓技术应用于家用空气源热泵，研究结果表明：该热泵的低温运行工况可低至-35℃;-15℃制热工况的COP可达到1.92;-30℃制热工况下，热泵出风口温度可达47℃。     

采用涡旋压缩机的电动汽车空调准双级压缩热泵性能实验研究

为了解决电动汽车空调系统冬季采暖问题和抑制冬季恶劣工况下压缩机排气温度过高状况,本文采用补气增焓技术,设计了电动汽车准双级压缩热泵空调系统,构建了电动汽车空调准双级涡旋式压缩机性能测试实验台。采用5种不同室外环境温度工况,分别测试了单级和准双级涡旋式压缩机。结果表明:压缩机的排气温度随环境温度的降低而升高。5种工况下,单级涡旋压缩机的排气温度均高于准双级涡旋压缩机的排气温度,尤其在环境温度为-7℃时,准双级涡旋压缩机的排气温度降低了10℃。与单级涡旋压缩机相比,在低温工况下,准双级涡旋压缩机的排气质量流量提高了12.9%~17.4%,系统制热量提高了7.3%~8.3%,制热性能系数COPh提高了7.6%~8.2%。     

10000m~3/h空分设备单膨胀机与双膨胀机运行工况转换分析

10000 m3/h空分设备原设计有两种运行工况,由于公司生产需要,实施了空分设备由单膨胀机运行工况向双膨胀机运行工况的转换。详细介绍了工况转换前的空分设备运行情况、转换预案、实施双膨胀机工况转换的具体过程。     

蓄冰空调主机分析及其节能措施的探讨

根据国内外厂家情况，推荐了蓄冰工况参数，分析了蓄冰空调主机在空调工况及蓄冰工况下的运行特点，２介绍了应用双膨胀阀或电子膨胀阀，双功能双蒸发器，带节能器的二次吸气式系统及螺工压缩可变内容积比调节等主机节能措施。     

变流量双级压缩制冷系统实验研究

为改善变工况条件下,定频双级压缩制冷系统不能达到最佳状态运行的现状,本文搭建变流量双级压缩制冷系统实验台,分析了变工况条件下,调节高压级压缩机频率来改变低高压级压缩机输气量之比,对一次节流中间不完全冷却造成的影响。结果表明：当冷凝温度为30 ℃,蒸发温度为?35~?20 ℃,低高压级压缩机输气量之比由1.25增至3.33时,系统制冷量随着低高压级压缩机输气量之比的增加逐渐减少,性能系数COP最大为2.37;当蒸发温度从?20 ℃降至?35 ℃,每降低5 ℃,最佳COP下的低高压压缩机输气量之比依次增大22.10%、12.52%、14.29%。故实际系统设计时,可参考实验数据,根据不同蒸发温度和制冷量需求,调节合适的低高压级压缩机输气量之比,使系统运行达到最佳状态。     

制冷循环的实际运行工况与节能

一、制冷循环的实际运行工况在分析制冷循环时,常用 lgP—i 图。在采用氨双级压缩带中间冷却器时,其循环过程为图一。常用该图来说明制冷的循环过程,计算制冷量,选择压缩机等。但用该图计算得出多点的参数,与实际运行过程的参数相比,仍有较大的出入。首先表现在高、低压级的排汽温度,实际运行温度比计算出来的结果往往高出15℃,甚至20℃以上。其次是压力,理论计算中,低压级排出的压力就是高压级的吸入     

冰蓄冷系统双压缩机串／并联组合式制冷机的性能分析

本文分析了变工况对制冷机的性能影响, 并对双压缩机串／并联组合式制冷机和常规冷水机组的制冰和空调工况的性能参数进行了理论研究,结果表明双压缩机串／并联组合式制冷机能在较宽温度范围进行调节并能高效运行, 特别是在制冰工况具有明显的节能效果。     

两种双级压缩制冷循环的理论分析

本文针对一级节流、两级节流,中间不完全冷却双级压缩理论制冷循环的制冷系数分别进行了理论推导,在相同制冷工况条件下,对两个循环的制冷系数大小进行了理论比较,为实际应用中循环的选择提供了理论依据,同时得出了两级节流、中间不完全冷却双级压缩理论制冷循环的特性。     

蓄冰空调主机分析及其节能措施的探讨

根据国内外厂家情况,推荐了蓄冰工况参数,分析了蓄冰空调主机在空调工况及蓄冰工况下的运行特点,介绍了应用双膨胀阀或电子膨胀阀、双功能双蒸发器、带节能器的二次吸气式系统及螺杆式压缩机可变内容积比调节等主机节能措施,对国内研制和生产蓄冰空调主机有一定的参考价值。     

火电厂前置泵泄漏原因分析及处理

从前置泵的选材、运行条件、设计方面分析了前置泵的泄漏原因,并提出了一些相应的解决办法,对于前置泵的维护和检修有一定的借鉴意义。     

Energetic and economic analysis of trans-critical CO2 booster system for refrigeration in warm climatic condition

The performance of five CO₂ booster refrigeration systems is analysed and compared in this paper for supermarket application. The investigated configurations include a standard booster system, abbreviated as BC1, a booster system with parallel compressor (BC2), a booster system with flooded low temperature evaporator (BC3), a booster system with work recovery expander (BC4) and a booster with parallel compressor along with flooded low temperature evaporator and work recovery expander (BC5). Annual hourly averaged temperature variations at four prominent cities across the world are taken as case study. Simulation indicates advantage of the proposed system BC5 over BC1 configuration. Work recovery unit is found to have the highest potential in the annual energy savings in BC5, followed by parallel compressor and flooded evaporator. The maximum annual energy savings is found to be 22.16% for BC5 in New Delhi. Economic analysis reveals recovery time of less than four years for the additional investment made in BC5. The slope of recovery time is found steeper at lower tariff compared to that at higher tariff.     

爪式无油增压传输真空泵的设计

爪式无油增压传输真空泵的设计和制造,使其成功的应用于各种气体物料在真空负压条件下的增压传输工艺作业,成为核燃料浓缩工业等现代高新技术领域最新的科技成果,对于化工和其他工业应用爪式无油真空泵进行气体物料增压传输工艺作业也具有指导意义.本文简要的叙述了爪式无油增压传输真空泵的设计依据、技术要求、驱动传动系统、结构选择及其工作原理.该系列产品在实际应用中也取得了良好的效果.     

Effects of vehicle seat and belt geometry on belt fit for children with and without belt positioning booster seats

A laboratory study was conducted to quantify the effects of belt-positioning boosters on lap and shoulder belt fit. Postures and belt fit were measured for forty-four boys and girls ages 5–12 in four highback boosters, one backless booster, and on a vehicle seat without a booster. Belt anchorage locations were varied over a wide range. Seat cushion angle, seat back angle, and seat cushion length were varied in the no-booster conditions.     

莱芜天元KZONAr-8700/6000/370型空分设备改造

针对莱芜天元5# KZONAr-8700/6000/370型空分设备存在的过冷器阻力大、空气增压机控制系统老化和放空阀内漏等问题,实施氮气、污氮气管路系统,以及空气增压机控制系统的改造,增加加工空气量,降低上塔操作压力,提高了氧、氩的产品产量。简介空分设备需改进的方面,阐述改造方案及其可行性分析和具体的实施过程。     

Magnet systems for the Daresbury synchrotron radiation source

The design, production and testing of the main dipole and quadrupole magnets for a 2 GeV electron storage ring are described, with particular emphasis on the integrated field performance including the optimisation of magnet ends. In addition fast pulsed kicker and septum magnets for control of injection and extraction processes in both the storage ring and its booster synchrotron injector are treated. All magnets are now installed and operating routinely in the new Synchrotron Radiation Source at Daresbury.     

进气口导流叶列对M型分子/增压泵抽速的影响

分子/增压泵抽气槽的入口流导是限制抽速的主要原因.抽气槽进气口增设一组百叶窗式导流叶列,可以显著减少入口流导的影响,大幅度提高抽气槽的抽速.本文分析了导流叶列的工作机理,提出了叶列参数优化方法,优化后的抽速可以提高20%.实测结果与理论值符合得很好.     

Accessory child safety harnesses: Do the risks outweigh the benefits?

Accessory child safety harnesses are available in some countries as alternative restraints for young children or as an accessory restraint used with booster seats. Their use, in Australia at least, is becoming more common. There have been concerns that the risk of misuse of these restraints outweighs any potential benefit this system might have over a retractable lap-shoulder belt system used with a booster seat. However to date there is no evidence to confirm or deny this. This study used laboratory simulated frontal crash tests to examine the performance of accessory child safety harness systems compared to the lap-shoulder belt when used alone and when used with two common designs of Australian booster seat. The performance of the child safety harness system when misused was also investigated. The results demonstrate that the correctly used child safety harness system performed no better than the lap-shoulder system, and in fact allows for a greater risk of submarining. Furthermore, one common form of child safety harness misuse, where the harness is over-tightened causing the lap belt to be positioned high over the abdomen, allowed extremely undesirable dummy motion. This involved gross submarining and direct contact between the harness system and the dummy's neck. These findings suggest that the risks associated with accessory child safety harness systems most likely outweigh any potential benefits, in frontal impacts at least.     

水锤波试验系统研究

建立液压水锤波试验台,提出了多参数可调的液压管道水锤波试验系统方案,通过改变增压缸活塞杆质量、调整增压缸活塞杆缓冲阻尼器的阻尼系数,实现对水锤波波形超调量、升压率及振荡的控制.     

Factors influencing the use of booster seats: a state-wide survey of parents

This study used telephone interview data on booster seat use from a state-wide probability sample of parents with children ages 4-8-years-old who were living in Michigan. Interviews were completed with parents of children in 350 households. Analyses examined the entire sample, and three sub-groups: always users, part-time booster seat users, and booster seat non-users. Results indicated that booster seat legislation was a key determinant of the level of use and the motivation to use booster seats. Nearly 70% of part-time users said that they used booster seats because they believed it was the law. Similarly, 60% of part-time and non-booster seat users said that they would be more likely to use booster seats if use were mandated by law, with non-users being 3.5 times more likely than part-time users to agree that a law would increase their booster seat use. Finally, over 90% of part-time and non-booster seat users said it would be easier for them to use booster seats if a law required it, and non-users were almost six times more likely than part-time users to agree that a law would make use easier. The need for booster seat laws, issues of social equity, and implications for intervention were discussed.