基于PLC 的中央空调制冷系统变频控制研究

针对现有中央空调系统能源消耗严重的现状,基于可编程逻辑控制器(Programmable Logic Controller,PLC)对中央空调系统进行变流量节能改造。分析改造后中央空调系统的结构组成和变频运行原理,并提出适用于冷冻水泵和冷却水泵的分段速温差控制和PID温差控制设计方案。控制硬件选用三菱FX3U系列PLC和台达VFD-EL变频器,软件选用GX Work2编程软件及力控组态软件。将控制方案进行实验验证,实验结果表明,所设计的两种控制策略不仅跟随系统末端负荷变化快速达到稳定运行状态,提高运行能效比,而且节能效果显著,节能率分别为40.2%和48.7%。     

基于MATLAB的空调用压缩机的建模与仿真

介绍了空调用压缩机的建模方法,选用合适的性能参数并采用MATLAB软件进行建模仿真,获得了良好的效果,为空调用压缩机的进一步仿真优化与结构设计提供参考价值。     

大承载气浮回转工作台的调心技术

为了实现大口径光学元件表面轮廓的高精度测量,提出了一种大承载气浮回转工作台的调心技术,并研制了一套具有偏心自动调整功能的测控系统。该系统主要由精密气浮回转轴、台达PLC、数显千分表和轮廓仪工作台组成。利用VC++的PLC串口通讯和偏心调整软件的控制,实现了轮廓仪的自动调心功能。     

活塞压缩机缸内热力过程CFD仿真

使用Fluent软件对压缩机缸内气体流场进行模拟研究,构建气缸的三维模型,以连续性、能量和动量方程作为基本控制方程,设置动网格基本参数,进而得到气流在气缸内的流场变化过程。分析缸内气体的流动状态包括压力、温度、湍动能等参数的微观变化情况,为优化改进压缩机性能提供依据。     

低温冷冻系统神经元PID变容量控制试验研究

为进一步提高低温冷冻系统运行稳定性及能效比,采用神经元PID解耦方法联合控制压缩机及电子膨胀阀以实现系统高精度变容量控制,解决压缩机频率和过热度耦合性问题.通过对低温冷冻系统传统双位调节控制、PID控制及神经元PID控制进行对比试验研究及分析,其试验结果显示:采用神经元PID解耦控制算法的-18℃冷冻库降温时间相比传统...     

基于自适应模糊控制的节能装置研究

针对凹版印刷干燥设备,设计节能装置,该装置利用压缩机换热原理,对余热进行再循环利用。设计自适应模糊PID节能控制系统,完成对压缩机,调功器,变频器的实时控制。利用组态软件完成系统界面设计,人机交互简洁,操作方便。控制算法采用自适应模糊PID控制,依靠数据信息来调整模糊逻辑系统的参数,通过在线计算得到最佳控制器参数,抑制不确定性对系统的影响。将节能装置应用到凹版印刷机,实验数据显示,系统耗能减少,效率得到提高,达到节能目的,证明了节能系统的有效性,具有较强的应用价值。     

轴流压缩机叶栅内固体微粒沉积的数值研究

本文针对轴流压缩机叶栅内固体微粒沉积的问题,采用计算流体动力学(CFD)软件对压缩机叶栅内的气固两相流动进行了模拟。文中首先采用不同的湍流模型和不同的壁面处理方法计算了垂直圆管内固体微粒的沉积,并与实验数据进行了对比。在此基础上,研究了轴流压缩机叶栅内不同直径粒子在叶片压力面和吸力面的沉积规律;且研究了不同工况对粒子沉积的影响。     

CAES离心压缩机可调扩压器调节规律研究

离心压缩机是压缩空气储能系统中关键设备之一,需具备在较宽流量、压力范围内高负荷高效率运行的能力。作为一种变工况调节技术,可调扩压器可以扩大压缩机工作流量范围,改善气动性能。因此,本文以某压缩空气储能系统用离心压缩机为研究对象,通过数值计算方法研究了可调扩压器调节时压缩机性能变化规律。结果表明采用可调扩压器可以有效拓宽压缩机运行特性,工作流量范围扩大44%,压比范围扩大25%.此后,本文采用Kriging模型获得了压缩机综合性能曲线图和不同储能工况需求下扩压器的调节方案及规律,为压缩空气储能系统离心压缩机变工况主动控制提供了依据。     

HL-2A装置低杂波高压电源逻辑控制保护系统

HL-2A装置低杂波高压电源的主回路设备是在原有的电源基础上改造重建的，但其逻辑控制保护系统却是新研制的，针对低杂波高压电源其输出电压高的特点，其控制保护系统就显得尤为重要。这套控制保护系统是在PLC基础上，采用SIEMENS STEP7软件编程实现的。     

高效斯特林制冷机性能实验研究

围绕某型号研制任务需求,自主研制了一种气动分置式斯特林制冷机,制冷机采用动磁式直线电机驱动、压缩机对置结构,压缩机及膨胀机均采用膜片弹簧支撑方式。基于sage软件完成整机热力学、结构相关设计,针对影响制冷机的主要因素：密封间隙、充气压力和膜片弹簧刚度开展了相关的理论和试验研究,获得了压缩机与膨胀机最佳的匹配状态,样机在60 W_AC输入功率下制冷量不低于3 W/80 K,制冷机效率可达5%以上。     

供水温度对CO2空气源热泵系统性能的影响

为探究热泵供水温度对CO2空气源热泵系统性能的影响,保持室外环境温度15.5℃不变,调节热泵供水温度,测试冷却水流量、气冷器出水温度、压缩机排气温度、气冷器CO2进出口温差、压缩机排气压力、压缩机耗功量、系统制热量、气冷器热交换完善度、系统COP的变化情况。结果表明:供水温度由45℃升至85℃,气冷器出水温度、压缩机排气温度、气冷器CO2进出口温差、压缩机排气压力随之增加,冷却水流量随之减小。系统制热量增加了7.3%、气冷器热交换完善度下降了20.0%、系统COP下降了35%、压缩机功耗增加了65.1%。     

真空冷却过程中实验条件对真空冷却速率的影响

以熟肉为实验材料,对实验条件对真空冷却速率的影响进行了理论分析和实验研究。实验结果表明:真空室有效容积越小、真空泵抽速越高,则真空冷却时间就会越短;冷阱温度对真空冷却速率有着明显的影响;当真空室内的最终压力在0.4～0.61kPa变化时,熟肉的表面温度一直在0℃以上,其真空冷却的时间随着真空室内压力的升高而增加。而真空室内的最终压力在0.3kPa左右时,熟肉的表面温度在真空冷却过程会低于0℃。     

An evaluation of a rankine cycle driven heat pump

This paper discusses a configuration of a Rankine cycle engine-driven heat pump, and includes a theoretical investigation of its performance characteristics. The system employs a Rankine power cycle, using R-113 as the working fluid, coupled to a vapour compression cycle heat pump using R-22. A novel feature of the concept is the use of hydraulically connected rolling diaphragm piston-cylinder devices as motor, compressor and pump.Heating and cooling COPs of 2.01 and 1.06 respectively are predicted, making the system potentially attractive where both heating and cooling are required.     

冷冻靶制备用低温氦气循环系统

常温高压渗透充气、低温冷却的冷冻靶球,需要20K以下的低温循环氦气,用于冷却高压渗透室和低温恒温腔。本套系统采用GM制冷机为冷源,采用专用氦压缩机为循环泵,设计高效率的回热式换热器,实现末端的20K以下低温氦气,通过低温氦气冷却终端部件,实现了20K的低温恒温环境和渗透室的冷却。     

压缩机的不同配置对热泵空调器性能的影响

同一房间空调器系统往往会采用不同类型的压缩机,由此带来系统的状态参数会发生相应变化。文中借助系统仿真计算,分析了不同压缩机配置对制热循环、制冷循环中性能特征影响及毛细管、R22的需求关系的变化;提出了针对不同配置的房间空调器的热泵性能最佳匹配的原则和方法;并在3200W热泵系统设计中得到了验证。     

压缩系数可控的光脉冲压缩器

提出了一种压缩系数可控的光脉冲压缩器.该脉冲压缩器主体包括梳状色散分布光纤（CDPF）和喇曼放大器两部分.梳状色散分布光纤由多段色散位移光纤和单模光纤拼接而成,具有喇曼增益介质的功能.对一给定的光脉冲序列,可以通过控制泵浦功率实现脉冲压缩器的压缩率可调.通过对非线性薛定锷方程的数值模拟,这一光脉冲压缩器的性能得到了验证.当光脉冲在CDPF中传输时,脉冲得到压缩并且被放大.对喇曼泵浦功率来改变可以得到不同的输出脉宽.通过优化CDPF的结构,得到了喇曼泵浦功率和压缩系数之间很好的线性关系.     

Rigorous investigation of heat pump assisted distillation

In this work a propylene-propane splitter assisted by a heat pump of the vapour recompression type is investigated by rigorous methods. Two schemes, a single compressor scheme and a double compressor scheme in parallel arrangement, are scrutinised and compared to the conventional stand alone column. The investigation includes parametric study, operability assessment and an estimation of the role of heat pump in minimising flue gas emissions. The parametric study of the influences of the column top pressure and the pressure lift of the heat pump on the economics shows, for both schemes at the optimal conditions, practically the same annual total cost, which is about 37% cheaper than the conventional stand alone column.The operability of the system is investigated by degrees of freedom analysis and steady state controllability parameters. The operability considerations show that in the case of the double compressor scheme, the column pressure can be independent of the threshold temperature of the condenser. Thus the column pressure can be determined to satisfy the optimum separation parameters. Due to this operability reason, the double compressor scheme is preferred to the single compressor scheme. The heat pump share in reducing flue gas emissions is estimated. It is found that about 60% of the flue gas emissions can be minimised when using a heat pump.     

Sorption refrigeration research at JPL/NASA

Since 1979, long-life, reliable heat-powered sorption refrigeration systems have been developed for spacecraft use at the Jet Propulsion Laboratory (JPL). JPL has successfully built and tested a series of cryogenic sorption refrigeration systems for spacecraft sensor cooling and is presently assembling a −263°C (10K) hydride sorption refrigerator, which will fly on the Space Shuttle in 1994. With the addition of novel regenerative heating techniques, this same technology has more recently been applied to design high efficiency, ground-based adsorption heat pumps. Using actual sorption isotherm data and detailed analytic thermal computer models, analysis has predicted that the cooling and heating COPs will be significantly better than for any other single stage, heat-powered heat pump. Specifically the cooling COP (COP_c) with the new regenerative system using ammonia is predicted to be as high as about 1.16. Recent tests on a single carbon sorbent canister compressor have been performed with R22, R134a, and ammonia. Transient thermal response of the sorption compressor has compared well with computer predictions. With ammonia, the total amount of average cooling from the 0.51 kg bed of carbon has been measured to be about 1038 Btu h⁻¹ (304 W) for a 6 min full cycle including both heating and cooling.     

Blowby flow rates to assess energy loss in cascaded refrigeration-heat pump systems

Available equation to determine the mass flow rate of ideal gas in an adiabatic flow through a duct of constant cross-section is modified after introducing isentropic exponents corresponding to a real gas. The equation is then used to compute theoretical blowby rates for cascaded refrigeration-heat pump systems. Most widely used and comparatively cheaper refrigerants R-12, R-22 and R-717 are selected for the heat pump system and R-13 for refrigeration sub-system. The rates are compared with ideal gas rates over a variety of operating conditions and a considerable loss energy is found with blowby rates. This loss can be averted, if a microprocessor is used to monitor instantaneous refrigerant mass at evaporator inlet and to compare this with the preset design mass and the difference (blowby) after cooling, it is feedback by an innovated method from the crankcase side of the compressor.