共查询到20条相似文献,搜索用时 906 毫秒
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应用热解法进行黄连木籽油热解实验。对热解产物做气相色谱-质谱分析,结果表明,黄连木籽油热解产物的成分大部分为烷烃和烯烃,碳链长度为11~18。通过分析热解产物与黄连木籽油的关系,发现甘油三酸酯在热解过程中,酯基的α和β碳原子之间的价键发生断裂。测定热解产物的物性,与柴油相比较得出,黄连木籽油热解产物的低热值稍低于柴油,运动粘度与柴油相当,闪点低于柴油很多。基于Vogel方程导出了热解产物的粘温关系式。 相似文献
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董尧清 《内燃机燃油喷射和控制》1996,(3):9-14,31
提出了一种实验表达式,作为确定最佳喷孔直径的有效方法,为得出这一表达式,使用燃烧分析仪测量气缸压力,对80个循环的气缸压力值进行平均。高压油管压力传感器接在喷油器体进油口处。针阀升程用电感式针阀升程传感器测定。根据实现数据提出了计算直喷式柴油机喷孔直径的表达式。所提出了的表达式的可靠度已由从5种不同柴油机上取得了实验数据所证实。结果表明,在发动机处于高速时,由表达式算出的喷孔直径值与实际油嘴喷孔值 相似文献
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随着投产时间的推移,水电站轴承油槽盖密封被逐渐磨损,动静配合间隙增大,油雾逸出现象严重。为了探究磨损间隙和机组转速对油槽密封处油雾泄露的影响,建立了发电机推力轴承油槽密封几何模型,应用SSTκ-ω湍流模型,对不同间隙(0.2~2.0 mm)、不同转速(100~500 r/min)下油雾的泄露情况进行稳态数值模拟计算。结果表明,建立泄漏量、间隙值及转速三者之间的函数关系表达式,可发现间隙值对油雾泄漏量的影响比转速高;间隙增加后,密封齿的节流作用减弱,密封进口压力降低,加剧了油槽盖顶部的油雾泄露;进、出口处的流速随间隙值的增加而增大,当间隙值由0.2 mm增加至2.0 mm时,进口速度由20 m/s增加到113 m/s,出口速度由76 m/s增加到144 m/s,泄漏量由0.034 4 kg/s增加到0.053 8 kg/s。该研究可为水电站轴承油槽密封结构的优化、电站运行策略的制定及密封性能的判断提供一定的理论基础。 相似文献
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670t/h锅炉屏式过热器爆管原因分析及其解决方案 总被引:2,自引:0,他引:2
通过对T型炉屏式过热器系统的流量分配、热偏差、壁温、强度等详细计算分析,找出了该炉运行以来发生屏式过热器管子超温爆管的主要原因是,原设计屏式过热器系统连接方式不合理引起的大的流量偏差,导致少数受热强而流量小的管子超温爆管。提出了5个改进方案,从中择其一个实施之。经实测,与计算值较好吻合,验证了理论分析计算方法的可靠性。图7表5 相似文献
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对行星差动轮系与液粘传动装置相结合的绞车进行启动过程的动力学分析,利用MATLAB软件进行仿真分析,得到了液粘传动装置的力矩控制函数.通过对液粘绞车启动过程进行模拟,表明液粘绞车能很好的按照给定的Harrison曲线进行启动. 相似文献
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过热蒸汽温度是锅炉的一个重要参数,对每一台锅炉都有一个严格要求的过热汽温,其误差范围一般都在10℃之内,因为它的大小直接影响汽机的安全和经济。过热汽温与锅炉燃用燃料性质关系很大,为一种燃料设计的锅炉,换了一种燃料,汽温往往就不能满足要求。过热汽温与锅炉负荷也有很大关系,随着负荷的降低,过热汽温一般也降低,为了保证低负荷的汽温,在满负荷就必须对汽温进行调节,即必须用某种方法降低汽温。过热汽温还与运行时运行工况的控制有关,例如与炉膛温度、过剩空气的大小有关。煤粉炉与火焰中心位置有关。循环流化床锅炉与物料的循环量有关。因此对已知锅炉还可以控制运行参数来控制汽温。 相似文献
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Muhanned A. Hararah 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2016,38(13):1904-1911
In this study, the effect of temperature and mixture composition on viscosity of Jojoba oil-Biodiesel (JO-BD) and Jojoba oil-Diesel (JO-PD) blends are investigated. Moreover, the relationship between the viscosity and the specific gravity of the blends is studied. Experimental viscosity data for the temperature range between 20°C and 80°C are used. The results show that the viscosity–temperature dependency can be well correlated by Vogel model for the viscosity–temperature relation. Also, a method that could estimate the blends viscosity from the specific gravity data is established. 相似文献
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In this paper, an empirical correlation for the nanofluid viscosity is proposed. The new equation for the nanofluid effective dynamic viscosity, normalized by the dynamic viscosity of the base liquid, is derived from a wide selection of experimental data available in the literature. This correlation presented the viscosity of the nanofluid as a function of the base fluid viscosity, nanoparticle volume fraction, nanoparticle diameter, nanoparticle temperature, and mass density of the base fluid. The new correlation was evaluated against 898 experimental data for the viscosities of nanofluid collected from the literature. The experimental data included different working nanofluids, such as alumina, Iron, and silica, where the diameter of nanoparticles was ranging between 10 and 350 nm, suspended in water, propylene glycol, and kerosene. The predicted results were then compared with many other published experimental results for different nanofluids and very good concordance between these results was observed. In general, this correlation has higher accuracy and precision. 相似文献
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为探究温度对生物柴油-乙醇-柴油三元燃料运动黏度的影响规律,以大豆油、小桐子油和餐饮废油生物柴油-乙醇-柴油3种燃料为研究对象,建立三元燃料“运动黏度-温度”高精度数学模型,该模型复相关系数均在0.99以上,最大误差为0.03,能精确预测燃料运动黏度随温度的变化规律。结果表明,餐饮废油混合燃料的黏度梯度最大,受温度影响程度最高,流动性能变化显著。3种三元混合燃料的临界预热温度分别为59.1、63.4和61.7 ℃,燃料在预热温度之下运行成本最低、雾化效果最佳。 相似文献
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含磷共聚物钻井液降黏剂合成及性能评价 总被引:1,自引:1,他引:0
以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和含磷化合物共聚合成了抗220℃高温的钻井液降黏剂,对含磷化合物用量、引发剂(过硫酸铵)用量和滴加温度等对钻井液降黏剂特性黏度和降黏率的影响进行了考察。结果显示,钻井液降黏剂的最佳合成条件为:含磷单体用量为反应单体总质量的6%,过硫酸铵用量为反应单体总质量的2%,滴加溶液温度为55℃。利用红外光谱(IR)对钻井液降黏剂进行了表征,并借助热分析考察了钻井液降黏剂的热稳定性,同时对其在泥浆中的降黏性能进行了室内评价。研究结果表明:研制的钻井液降黏剂可以显著降低泥浆的黏度和切力,加入0.5%降黏剂的淡水基浆,高温降黏率可以达到91.4%;具有较好的抗盐、抗钙性能,在饱和盐水泥浆和含钙泥浆中也具有很好的降黏作用和分散作用;具有较好的热稳定性。 相似文献
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This study investigates the effects of variable viscosity and frictional heating on the laminar flow in a horizontal channel having a wall at rest and a moving wall subjected to a prescribed shear stress. The wall at rest is thermally insulated, while the moving wall is kept at a uniform temperature. This investigation concerns fluids whose viscosity depends exponentially on the pressure and temperature. An appropriate approximation is introduced to analyze the interplay between the dependence of viscosity on the pressure and temperature and the viscous dissipation. It is shown that the nonlinear term in the equation for the balance of energy representing the frictional heating may lead to the existence of dual solutions of the boundary value problem for fixed values of the material parameters that characterize the fluid. The results obtained are compared with those predicted by the generalization of the Oberbeck-Boussinesq approximation for a fluid with pressure and temperature dependent viscosity. It is found that the results for the approximation carried out in this paper and those that stem from the Oberbeck-Boussinesq approximation are markedly different. 相似文献
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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。 相似文献
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Shahram Derakhshan Mohammad Rezaee Hamid Sarrafha 《Nanoscale and Microscale Thermophysical Engineering》2015,19(3):206-220
Equilibrium molecular dynamics simulation was utilized to calculate the shear viscosity of monoatomic molecules liquid flow confined in a nanochannel in the pure state and their binary mixtures. The pure flow viscosity data of argon, krypton, and xenon were used to predict their binary mixture viscosities using prediction methods proposed in the literature. Each method was evaluated by comparison of its results with those obtained by validated molecular dynamics simulation at different temperatures. In addition, correlative methods for mixture viscosity estimation and temperature dependence models were evaluated and corresponding model parameters were obtained. Moreover, the relations representing mixture parameter values as a function of the pure ones were determined and evaluated according to their accuracy. 相似文献