液态碳氢燃料高压低温粘度测量实验研究

在Hagen-Poiseuille定律的基础上,利用双毛细管法,设计了一套适用于液态碳氢燃料高压低温粘度测量实验系统,测量压力:0.1~10 MPa,温度测量范围:233.35~313.75 K,扩展相对不确定度为:2.10%~5.08%(置信因子k=2)。实验在利用纯物质正己烷和质量比1:1正庚烷-正辛烷二元混合物对测量系统可靠性进行验证的基础上,测试了两种碳氢燃料A、B压力0.7、1.5、3和6 MPa,温度:233.55~313.65 K下的粘度值,结果表明:在相同压力下,两种燃料的粘度值随温度的增加而减小;在233.55~273.25 K附近,两种燃料粘度值随温度的变化率要大于273.25~313.65 K,表明低温区碳氢燃料A、B粘度受温度的影响比高温区大,且温度越低温度的影响程度越大;在233.55~273.25 K低温区范围内,燃料A粘度值受温度的影响程度要小于燃料B。实验中还发现,当温度接近231.25 K时,燃料B在毛细管中瞬间凝固,系统压力急剧升高,而燃料A在此温度下依然处于液态。在相同温度下,两种燃料的粘度值随着压力的增加稍有增大。此套高压低温粘度测量系统简单可靠,测量精度高,能够实现液态碳氢燃料高压低温粘度的在线测量。     

高温下吸热型碳氢燃料定压比热容在线测量

为提高吸热型碳氢燃料高温高压条件下比热容的测量精度,基于能量守恒的量热计理论,设计一套适用于高温高压的碳氢燃料定压比热在线测量系统。系统温度测量范围为450~900 K,测量压力可达10 MPa。选取环己烷和质量比1∶1正己烷-正庚烷二元混合物对测量系统进行标定,实验结果与文献的相对误差在±1%以内,相对误差绝对平均值小于0.32%。在此基础上对两种不同成分的吸热型碳氢燃料的定压比热进行了测量,温度为450~900 K,压力为2.0~5.0 MPa。实验结果表明:在低温区域范围内,碳氢燃料的比定压热容随温度的升高呈现近线性增长;在拟临界、临界温度时达到一个峰值,且峰值随压力的增加逐渐减小,且所对应温度点不断后移;大比热区后,燃料的比热容值随温度的升高急速增大。该测量系统的应用可为进一步提高碳氢燃料比热的测量温度范围创造条件。     

不同浓度配比硼酸溶液比定压热容的实验测量

采用高精度的流动型量热法测量了温度在303~396K、压力在0.1~0.5MPa范围内,浓度分别为7000ppm、40000ppm(无杂质)和40000ppm(含杂质)三种配比硼酸溶液的比定压热容。实验系统的温度、压力、比定压热容的测量不确定度分别小于±0.05K、±18kPa、±0.28%。为了验证实验系统的测量精度和可靠性,测量了温度为296~396K、压力为0.1~6MPa范围内纯水的比定压热容,与NIST文献值相比的相对偏差绝对平均值为0.41%。     

吸热型碳氢燃料高压低温密度测量实验研究

为实现吸热型碳氢燃料的低温密度在线测量,基于计数率模式下的gamma(伽马)射线衰减原理,设计一套适用于高压、低温的碳氢燃料密度测量系统,温度测量范围:233~333 K,最高压力达到10 MPa,合成相对标准不确定度为:0.13%~1.46%。分别通过正己烷和质量比1∶1正庚烷-正辛烷二元混合物对测试系统测量精度进行验证,实验结果表明:密度测量的最大相对误差控制在0.67%,相对误差绝对平均值分别为0.22%、0.07%。在此基础上,对碳氢燃料A在压力:0.7、3和6 MPa,温度:234.15~323.45 K时的密度进行测量,并计算碳氢燃料A等压热膨胀系数,结果表明,燃料A在三种压力下,等压热膨胀系数αp随着测试温度的升高而增加;低温下,高压不利于热量在流体中的扩散。实验中还发现,当温度接近230.65 K时,碳氢燃料在预冷管路中逐渐由液相变为固相,系统工作压力急剧升高。此套密度测量系统为开展吸热型碳氢燃料低温密度的测量创造了条件。     

变容积量热器法测量液体比热容实验研究

基于准稳态理论,建立了一种可以实时改变工作腔体容积的非流动型量热器,并自行搭建了比热容测量系统.通过测量温度为273.15～293.15 K常压下纯水的比热容,对实验系统的测量精度及可靠性进行了检测.结果显示,该实验系统的相对偏差绝对平均值为0.35%,验证了该套实验系统设计原理的正确性及实验装置的准确性.此外,测量了4种配比下,含油制冷剂R134a在温度为273.15～293.15 K,其饱和液体的比定压热容和比定容热容.     

二氧化碳/二甲醚混合工质热泵系统循环性能分析

在相同的工况条件下,对二氧化碳(R744)/二甲醚(RE170)混合工质与四种常见的热泵工质R22、R134a、R410A和R407C的亚临界循环性能进行了分析计算。结果发现,在R744/RE170质量配比为30/70下,系统的制热循环性能系数最大,其值为4.922,分别比R22、R134a、R410A和R407C系统提高了17.53%、30.52%、19.09%和16.52%;此时,系统的冷凝压力为2.276MPa仅高于R134a系统,压缩机压比为3.708,压缩机出口工质排气温度为92.6℃。     

基于KULI的带回热器的R134a与R1234yf汽车空调系统仿真分析

使用KULI软件建立了带回热器的一维汽车空调仿真模型,通过试验数据验证了该模型的可靠性,并分别对R134a和R1234yf的系统性能进行了仿真分析。仿真结果表明:R1234yf系统的冷凝压力比R134a低,蒸发压力比R134a高;R134a系统的排气温度比R1234yf高10.5~17.9℃;R134a系统的制冷量比R1234yf高1.6%~3.4%;R134a系统的COP比R1234yf高0.2%~4.2%。     

振动盘式粘度计工作方程的修正及R407C气相粘度的实验研究

对原有的振动盘式粘度计的测量原理进行了系统的分析，并测量了环保制冷剂R407C的气相粘度，从转动惯量，粘性力矩等角度重新分析了悬挂系统中上、中、下悬挂柱对整个测量结果的影响，进一步讨论了相位角的问题，重新确定了工业方程的修正项，用HCFC22进行了校验实验，粘度测量值与献值相比，最大偏差不大于4.5%，测量得到R407C的粘度数据32个，测量温度为295～352K，压力为0.1～2.34MPa，与献值相比，最大偏差小于4.5%，在实验数据的基础上，回归得到了其粘度随温度和密度变化的方程。     

碳氢燃料低温定压比热测量实验研究

基于流动型定压比热容测量方法,本文设计了一套适用于高压低温的碳氢燃料定压比热测量系统,温度测量范围:233.45~313.65 K,最高压力达到10 MPa,测量定压比热容的扩展相对不确定度为1.24%~2.20%(置信因子k=2)。实验在通过纯物质正己烷和质量比1:1正庚烷-正辛烷二元混合物对测量系统可靠性进行验证的基础上,测试了3种碳氢燃料A、B、C压力:0.7、1.5、3和6 MPa,温度:233.45~313.65 K的比热值,结果表明:3种燃料在4种压力下,定压比热分别随温度的增加而增加;在低温区,燃料A、B受温度的影响程度要小于燃料C;压力基本不影响碳氢燃料低温定压比热。该低温高压比热测量系统的建成为进一步开展碳氢化合物及其混合物低温定压比热的研究创造了条件。     

R1234yf/R152a用作汽车空调制冷剂的配比范围研究

使用PR方程结合vdW法则建立了R1234yf/R152a的热物性模型,在此基础上结合余函数法编制了R1234yf/R152a的热力性质和制冷系统循环性能计算程序。在汽车空调制冷工况下,获得了R1234yf/R152a在不同摩尔组分比下的压力比、排气温度、COP、单位质量制冷量、单位体积制冷量和压缩机吸气口比容,并与R134a和R1234yf/R134a(0.89/0.11)进行了比较。之后,结合燃烧速度、GWP与循环性能获得了适宜的摩尔组分比范围。当R1234yf的液相摩尔分数在0.65～0.67时,R1234yf/R152a为近共沸混合物,具有较高的安全性,且制冷循环性能与R134a较为接近。     

Experimental Study on Vapor Pressure of HFC—134a

As part of the study on thermophysical properties of HFC-134a,this paper concerns itself with vapor pressureof HFC-134a in the temperature range of 279.15K to 365.15K.A total of 43 measurement data were measuredduring the experiment which was conducted on a high precision PVTx test apparatus designed by the authorswith slight modifications.Uncertainties of temperature was ±10mK and of pressure was ±500Pa.Purity ofsample was either 99.95wt% or 99.98wt%.Data resulting from this experiment matched closely with the newestdata published internationally.Compared to our proposed equation for calculating vapor pressure of HFC-134a,the RMS deviation of experimental data was only 0.0531%,showing relatively high precision.     

高温条件下柴油机喷雾粒度的测量

为了了解柴油机燃烧室中燃油与空气的混合及后续燃烧过程，准确地描述燃油雾化和油洋蒸发过程是至关重要的。运用激光衍射法测量注体喷雾粒度具有对喷雾无干扰，设备简单数处理迅速等优点，但这种方法对加热环境中的蒸发液雾进行测量进，由于光路上存在的温度及浓度梯度，激光被折射而偏转，结果受到严重影响，以往对柴油机喷雾的测量大都在常温不蒸发条件下进行的，而本则是通过对粒子激光衍射测量原理的深入分析，对基于激光衍射     

Comparison of dilution effects of R134a and nitrogen on flammable hydrofluorocarbons

An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinese national standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a, R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambient temperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisons were made with the literature data; good agreement for most measurements was obtained. R134a was found to have a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.     

Adsorption Parameter and Heat of Adsorption of Activated Carbon/HFC-134a Pair

This article presents the adsorption isotherms of HFC-134a and activated carbon Maxsorb III measured using the constant-volume–variable-pressure method. The adsorption isotherms cover temperature ranges from 293 to 338 K and pressures up to 0.7 MPa. The trends of the experimental isotherms for activated carbon are found to be identical in all cases with previous studies except that the vapor uptake is slightly higher. The adsorption characteristic of the Dubinin–Ashtakov equation has been regressed from the experimental isotherms data and the maximum specific uptake is 2.15 kg of adsorbate adsorbed per kilogram of activated carbon. The heat of adsorption, which is concentration and temperature dependent, has also been extracted from the experiments.     

PVTx Study of Binary System R22／R152a with Burnett Method

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Research and development of liquid hydrogen (LH2) temperature monitoring system for marine applications

Monitoring the temperature in liquid hydrogen (LH₂) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa.     

利用PLIEF技术对重型柴油机类似环境条件下柴油喷雾特性和浓度场的定量研究

利用复合激光诱导荧光技术在定容弹内定量研究了环境温度、环境密度、氧浓度等对重型柴油机类似环境条件下柴油喷雾特性和浓度场的影响。试验中,环境密度为20～100kg/m3,氧浓度为15%～21%,喷油压力为100～220MPa。研究发现,提高环境密度,最大液核长度显著缩短;减小喷孔直径,液核最大长度呈线性下降。降低环境温度或提高喷油压力可以弥补减小喷孔直径或提高环境密度对贯穿距离的影响。在增加充分发展期气相喷雾稀混区燃油比例方面,减小喷孔直径、降低环境温度、提高环境密度和提高喷油压力具有相互替代性。     

柴油机高压喷雾雾场的温度测量

喷雾场的温度对燃油的蒸发，混合气的形成，着火以及火焰传播有着决定性影响。在进行数学模拟时，雾场温度是很重要但很难测量的参数，迄今尚少有直接测量结果的报道。本文用薄膜式热电偶测量了柴油机高压喷雾雾场内的温度随时间的变化。热电偶经氩离子脉冲激光器标定，其时间常数约为６０‘μｓ。燃油喷射压力为１０２ＭＰａ～１３４ＭＰａ。测量结果表明，在本实验条件下，雾场内的温度与环境气体温度相差只有８Ｋ～３０Ｋ左右，比预计值要小很多。而且，环境温度较高时，雾场内外温度差减小。这可能是由于热管效应的作用。喷油压力对雾场内外温差没有明显影响，雾场外围处比雾场中心处与环境的温差要小。近喷嘴处的温度测量值随时间单调下降，且与环境温度相差较大，表明此处燃油沉积作用比较明显。     

Comparative assessment of environment-friendly alternatives to R134a in domestic refrigerators

In the present work, the possibility of using R152a and hydrocarbon refrigerants (such as R290, R1270, R600a, and R600) as alternatives to R134a in domestic refrigerators has been assessed theoretically. The refrigerants are assessed over wider range condensing and evaporator temperatures. The assessment was done with standard parameters such as pressure ratio, volumetric cooling capacity (VCC), coefficient of performance (COP), compressor input power, compressor discharge temperature, and total equivalent warming impact (TEWI). The results obtained showed that pure hydrocarbon refrigerants are not suitable to be used as alternatives to R134a due to its mismatch in VCC. R152a has approximately the same VCC with about 9% higher COP and lower values of operating pressure and compressor input power. The discharge temperature of R152a was higher than that of R134a by about 14–26 K. TEWI of R152a was about 7% lower than that of R134a. The reported results proved that R152a is an energy-efficient and environment-friendly alternative to phase out R134a in domestic refrigerators.