变排量压缩机汽车空调制冷系统特性分析

为了解决变排量压缩机汽车空调系统振荡和蒸发器结霜问题,对该系统稳态特性进行分析。建立了变排量压缩机汽车空调制冷系统稳态模型,模拟结果与试验数据吻合较好。系统存在变排量压缩机定转速定行程、变转速定行程、定转速变行程和变转速变行程四种运行方式,本文对四种方式下汽车空调制冷系统的稳态特性进行了分析。研究首次发现,在变活塞行程情况下,与定行程方式下性能参数——对应关系不同,蒸发压力、制冷量等系统参数表现为多值对应关系,系统存在“性能带”,可使蒸发压力保持在一个较小的范围内变化。变排量压缩机汽车空调制冷系统性能带的发现和提出,丰富和发展了制冷系统特性分析理论。     

R290空调器的优化设计原则

在分析比较R290、R22、R410A三种工质热力性能的基础上,对采用R290工质的空调器提出了优化设计原则。优化设计原则主要针对压缩机、冷凝器、蒸发器、节流装置四大部件:R290空调器的压缩机应增加排量;R290空调器的冷凝器可采用小管径换热器;R290空调器的蒸发器可采用小管径换热器;R290空调器的毛细管应比R22空调器的长约39%,比R410A空调器的短约44%。在提出R290空调器优化设计原则的同时,本文对保证R290空调器安全性提出了建议。     

制冷系统中蒸发式冷凝器的性能优势

冷凝器是制冷系统主要的换热设备之一,其作用是将压缩机排出的高温过热制冷介质蒸汽冷却为液态。从20世纪70年代起,发达国家开始用蒸发式冷凝器代替水冷式冷凝器。而我国在近年也开始将蒸发式冷凝器应用于各类制冷系统中,其中包括冷库、中央空调、工业制冷机组、氨制冷系统等。蒸发式冷凝器的性能优势:(1)节水。蒸发式冷凝器充分利用水的汽化潜热,一般的水     

一种独立式内燃机驱动的船用空调装置试验研究

为了研究特种空调装置在中小船舶上的应用特性,研制了一种独立式内燃机驱动的空调装置.该装置采用小型内燃机驱动制冷系统:小型发电机为室内风机和水冷式冷凝器水泵提供交流电力,为柴油机电启动的蓄电池进行直流充电,并且为控制系统提供稳定的直流电力.根据各个部件的额定运行工况,对系统进行了可靠性综合测试.通过调节内燃机转速对系统进行了变工况试验,根据试验数据进行了结果分析,可以看出在保证系统可靠性的前提下调节内燃机转速和蒸发器风机转速可以实现船舱室内温度的精确调节,为我国内陆河流的中小船舶使用特种空调装置提供了一种新的选择.     

变排量压缩机汽车空调制冷系统特性分析

本文分析了变排量压缩机汽车空调制冷系统的关键部件变排量压缩机,建立变排量压缩机数学模型,分析变排量压缩机四种模式下的系统特性。变排量压缩机空调制冷系统性能分析,为实际的应用提供理论指导。     

平行流冷凝器应用于食品冷藏柜的实验研究

新型单、双排平行流冷凝器应用于冷柜制冷系统中,并与原管片式冷凝器冷柜制冷系统进行对比实验分析。结果表明,应用单、双排平行流和管片式冷凝器的冷柜制冷系统分别在充灌量为550g、650g和800g时,周期内压缩机平均功耗最小,其中双排平行流冷凝器周期内压缩机平均功耗最小,单排平行流和管片式冷凝器相当。平行流冷凝器的空气侧换热性能明显优于管片式冷凝器。实验所用单、双排平行流冷凝器仅为管片式冷凝器换热体积的四分之一和二分之一,将平行流冷凝器应用于冷柜系统中将有利于解决冷柜冷凝器在恶劣环境下运行换热量不足的问题和降低成本费用。     

一种新型的低温制冷系统设计

为了克服传统制冷系统蒸发温度很难达到-100℃的缺点,设计了一种新型的低温制冷系统,进行了系统混合工质的配比、热力参数的计算以及主要部件如:压缩机、冷凝器、组合换热器、毛细管的设计与选型,经过样机试验,结果表明各项指标均达到设计要求。     

采用水冷冷凝器的电动汽车热泵系统制热和抗结霜性能试验研究

热泵技术由于具有比电加热显著提升的制热效率,近年来逐渐应用于电动汽车以期提高冬季续航里程。文章设计了一套电动汽车热泵系统,该系统取消了传统热泵的车外冷凝器,而以低温散热器作为主要的散热和吸热部件。根据实车的零部件部件要求搭建了该热泵系统的测试台架,台架试验结果表明该热泵系统在-7℃环境下,纯热泵工况下的制热能力可以达到5.4 kW,COP可以达到2.4。通过模拟电机电控的余热回收效果,试验发现低于30%的余热可以被该系统吸收用于制热。试验也表明这种类型的热泵系统在湿度较高的情况下同样存在结霜的问题,且结霜开始的时间与环境湿度和压缩机转速关系紧密。     

小型制冷压缩机瞬态起动特性研究

在小型制冷系统中，转子式压缩机的制冷效果不及往复式压缩机，因而限制了转子式压缩机的推广应用。利用作者研制的起动电流测试装置，对不同结构的小型压缩机的瞬态起动特性进行了实验研究，提出了阻止工质在停机后的质量迁移来提高转子式压缩机制冷效果的观点．并进行了压差起动可靠性试验。本研究工作为转子式压缩机在小型制冷系统上的推广应用提供了理论依据。     

基于状态空间的制冷系统动态建模

为了建立适用于先进控制的制冷系统模型,对单级蒸气压缩式制冷系统的各个部件建立动态方程,通过合理的简化和推导,选取合适的参数作为状态变量,建立制冷系统状态空间模型。以某制冷系统为对象,首先通过动态仿真结果与试验数据比较,修正模型中的换热关联式,然后利用修正后的动态模型模拟某复杂扰量下该制冷系统载冷液和冷却液出口温度、压缩机功率、制冷量以及COP动态响应过程。再次对比模拟结果与试验数据,结果表明,载冷液出口温度和冷却液出口温度模拟值与试验数据之间的相对平均偏差在5%以内,压缩机功率、制冷量、COP模拟值与试验数据的相对平均偏差在10%以内,模型计算结果比较准确地反映制冷系统动态过程。     

汽车空调用制冷压缩机耐久性试验台研制

阐述了汽车空调压缩机试验台的设计方案及其工作原理。该试验台满足机械工业部标准和行业标准中汽车空调压缩机的耐久性试验要求,适用于小型汽车空调压缩机产品开发及定型产品抽检所要求的定排量或变排量耐久性试验以及启动耐久性试验,且结构简单、操作方便、可靠性好,有一定的推广价值。     

1.2m缩尺实验盾构机械结构与液压系统设计

 为研究盾构掘进时各物理参数之间的相互影响,进而确定相适应的工作参数,设计开发了全断面盾构掘进机综合模拟试验台．其中,用于模拟真实盾构掘进的缩尺盾构主要由刀盘系统、推进系统、螺旋输送机系统等组成．根据实验的需要,设计了缩尺盾构的机械结构,详细说明了结构设计的思想以及缩尺盾构的工作过程．设计了缩尺盾构的液压系统,详细说明了液压系统的工作原理、功能特点和选型计算．利用AMESim软件对刀盘液压系统和推进液压系统进行仿真分析.仿真结果显示,刀盘转速和缩尺盾构的推进速度都可以实时控制,所设计的液压系统能够满足实验需要.     

A mathematical model of variable displacement swash plate compressor for automotive air conditioning system

A mathematical model of control mechanism used in the variable displacement swash plate compressor (VDSC) is developed firstly based on the force balance equation, mass and energy conservation equation. The model of moving components dynamics is developed then by analyzing the forces and force moments acting on the pistons and the swash plate. The compression process model is obtained by fitting the data from our experiments. And finally, the steady-state mathematical model of VDSC is developed by combining the three sub-models above. In order to verify the mathematical model, a test bench for control mechanism and the test system for VDSC have been established, and the simulated results agree well with the experimental data. The simulation results show that, like the variable displacement wobble plate compressor, there are four operation modes for the VDSC, i.e. constant rotary speed and constant piston stroke length (PSL), variable rotary speed and constant PSL, constant rotary speed and variable PSL, variable rotary speed and variable PSL, which have included almost all operation modes of the refrigeration compressor in common use. And there is a hysteresis zone and multiple-valued relationship between the compressor parameters when PSL changes.     

电液谐振式高频疲劳试验台动态特性研究

针对由单出杆液压缸与二位三通2D阀组成的电液谐振式高频疲劳试验台,因单出杆液压缸无杆腔与2D阀相连,有杆腔恒通油源。而2D阀突破常规电液伺服阀频宽极限,具有宽频带、高频响等特点,通过改变阀芯旋转速度及阀口轴向开度,可对系统分别进行变频、变幅控制。对采用2D阀控制技术的电液谐振式高频疲劳试验台建立数学、仿真模型,并对该试验台谐振工况进行仿真与实验研究,结果表明该系统谐振工况输出位移（载荷力）与激振力大,消耗外界功率低。     

轿车空调系统的试验研究

对轿车空调系统进行性能试验，分析压缩机转速、蒸发器风量、冷凝器风量和环境温度等的变化对轿车空调系统性能的影响，为进一步研究轿车空调奠定基础。     

Modeling and experimental evaluation of an automotive air conditioning system with a variable capacity compressor

A steady state computer simulation model has been developed for refrigeration circuits of automobile air conditioning systems. The simulation model includes a variable capacity compressor and a thermostatic expansion valve in addition to the evaporator and micro channel parallel flow condenser. An experimental bench made up of original components from the air conditioning system of a compact passenger vehicle has been developed in order to check results from the model. The refrigeration circuit was equipped with a variable capacity compressor run by an electric motor controlled by a frequency converter. Effects on system performance of such operational parameters as compressor speed, return air in the evaporator and condensing air temperatures have been experimentally evaluated and simulated by means of developed model. Model results deviate from the experimentally obtained within a 20% range though most of them are within a 10% range. Effects of the refrigerant inventory have also been experimentally evaluated with results showing no effects on system performance over a wide range of refrigerant charges.     

基于蒸汽喷射制冷的汽车空调建模与控制

以汽车尾气为热源,建立蒸汽喷射制冷循环的数学模型。针对汽车蒸汽喷射制冷系统的特点,设计应用于汽车蒸汽喷射制冷系统的模糊自适应PID控制器,并与PID控制算法进行对比研究。仿真结果表明,模糊自适应PID控制器在变负荷、变工况等条件下都优于PID控制器,为蒸汽喷射制冷在汽车空调中的应用提供可行性方案。     

Fuzzy control of the compressor speed in a refrigeration plant

In this paper, referring to a vapor compression refrigeration plant subjected to a commercially available cold store, a control algorithm, based on the fuzzy logic and able to select the most suitable compressor speed in function of the cold store air temperature, is presented. The main aim is to evaluate the energy saving obtainable when the fuzzy algorithm, which continuously regulates the compressor speed by an inverter, is employed to control the compressor refrigeration capacity instead of the classical thermostatic control, which imposes on/off cycles on the compressor that works at the nominal frequency of 50 Hz. The variation of the reciprocating compressor speed is obtained by controlling the compressor electric motor supply current frequency in the range 30–50 Hz, as it is not possible to consider values smaller than 30 Hz because of the lubrication troubles due to the splash system. In this range, two among the most suitable working fluids proposed for the R22 substitution, such as the R407C (R32/R125/R134a 23/25/52% in mass) and the R507 (R125/R143A 50/50% in mass) are tested. Comparing the compressor speed fuzzy control with the classical thermostatic control, frequently used in the cold stores and in other refrigeration systems, the experimental results show a meaningful energy saving equal even to about 13% when the R407C is used as a working fluid. In particular, to explain from the energy saving point of view the best performances of the refrigeration plant when the compressor speed varies, an exergetic analysis is realized. Besides, with regard to the inverter cost, the pay-back period determined is more than acceptable for the plant size examined.     

电动汽车空调热泵型涡旋压缩机结构分析

为了解决电动汽车空调系统冬季采暖问题,针对冬季空调工况下压缩机单级压比增大的运行特性,以涡旋压缩机制热性能系数为热力学优化目标函数,确定了制冷剂循环系统中的最佳补气压力,优化了涡旋压缩机静涡旋盘上的中间补气口的几何位置和形状,使其具备了准双级压缩功能。将研发的热泵型电动涡旋压缩机安装于电动汽车空调系统,利用空气焓差法对系统进行了制热、制冷性能实验。实验结果表明,静涡旋盘结构优化后的热泵型电动涡旋压缩机,其制热和制冷能力可以满足5人座电动汽车司乘人员的冬季和夏季舒适性要求,并且具有较高的制热和制冷性能系数,从而提升了汽车空调系统热泵循环和制冷循环的热经济性,达到了节能的目的。     

Theoretical and experimental investigation on the performance of screw refrigeration compressor under part-load conditions

Slide valve is normally employed in screw refrigeration compressor to meet the cooling capacity demanded by the load variation. A mathematical model describing the working process of screw refrigeration compressor with a slide valve assembly under part-load conditions is established based on the calculation of the effective by-pass area and radial discharge area. Experimental investigation on a screw refrigeration compressor under part-load conditions with several evaporation and condensation temperatures is also carried out. Simulation results are in good agreement with the experimental ones. With the validated model, effects of key design parameters, i.e. the installation angles of the slide valve relative to the cylinder and the slide stop length, on the working process and performance of screw refrigeration compressor have been analyzed. These results can be useful for optimum design of the slide valve assembly to improve the energy efficiency of refrigeration system with screw compressor under part-load conditions.