High‐Purity Tocored Improves the Stability of Stripped Corn Oil Under Accelerated Conditions

γ‐Tocopherol‐5,6‐quinone (tocored) is of importance among the γ‐tocopherol (γ‐T) oxidant products and found in corn germ oil. Investigation on tocored is impeded in part by the difficulty to access high purity tocored. In this present study, high‐purity tocored is successfully prepared, and its antioxidant activity, together with γ‐T and TBHQ (positive control) in increasing concentrations in stripped corn germ oil is evaluated by Rancimat and Schaal oven tests. The stabilization factor in the Rancimat tests increases significantly (p < 0.05) along with an increase in the levels of antioxidants. Furthermore, tocored exhibits higher stabilization than γ‐T in the Schaal oven tests, although its efficacy gradually increases up to 100 mg kg^–1 and decreases significantly at higher levels (from 100 to 500 mg kg^–1), drawn from the comprehensive parameter A (considering both efficiency and strength) changes (5.06–11.21). In addition, the curves illustrating the residual contents of tocored and γ‐T run in different ways when the four levels are taken into consideration, further bearing the above results. Tocored tends to be a potent natural antioxidant for edible corn germ oil preservation. Practical Application: The present work provides more clear procedures for high‐purity tocored synthesis. Furthermore, tocored may be a potential natural antioxidant that is especially suitable for lipid base food substrates. The results of the present work contribute to the deeper understanding of the antioxidant activity of γ‐tocopherol. The antioxidant activity of tocored is higher than γ‐tocopherol in Schaal oven test. Tocored is a bright orange‐red substance that affects the appearance of the edible oil. Meanwhile, γ‐tocopherol is well known for its valuable health benefits, and appropriate measures should be adopted to store oils (corn oil, soybean oil, and so on) rich in γ‐tocopherol to control transformation in order to keep stability optimal. To some degree, the practical applications of the present results are also related to the processing and storage of edible oils.     

Simple Wet Rendering Method for Extraction of Prime Quality Oil from Skipjack Tuna Eyeballs

Oil from skipjack tuna (ST) eyeballs is extracted by the wet rendering method at 121 °C for different holding times (5–60 min) using an autoclave. Yield increases as heating time increases up to 20 min (p < 0.05); no further increase is obtained with a longer heating time (p > 0.05). Conversely, acid value and total polar compounds increase. However, peroxide value (PV), thiobarbituric acid reactive substances, and anisidine value (AnV) decrease up to 30 min. No changes in unsaponifiable matter (UM) or conjugated diene (CD) are attained, regardless of heating time. Polar components (PC) increase with heating time (p < 0.05). All oil samples have a high polyunsaturated fatty acids (PUFA) content (40.46–41.00%), with monounsaturated fatty acids (MUFA) and saturated fatty acids (SFA) in the range of 20.94–21.26% and 37.77–38.45%, respectively. PUFA content is reduced slightly with a heating time of 60 min. Docosahexaenoic acid (DHA) (C22:6, n3) is the dominant fatty acid in all samples (31.67–32.24%). Based on FTIR spectra, heating for longer time results in lower intensity at wavenumbers of 3015 and 1740 cm^?1. Thus, light yellow oil from ST eyeballs prepared by a green process for an appropriate time can serve as an excellent source of DHA and other PUFA. Practical Applications: Tuna oil is known to be a rich source of DHA and PUFA with health benefits. However, precooked tuna heads, generally used as raw material, yield oils with a very dark color and offensive odor, which require several refinery processes. To reduce the number of steps in the refinery process, tuna eyeballs which are separated from tuna heads can render higher quality fish oil. Moreover, the wet rendering process, a green process without toxic substances, can be used without causing environmental problems.     

Thermal and hydraulic characteristics of a large-scaled parabolic trough solar field (PTSF) under cloud passages

To better understand the characteristics of a large-scaled parabolic trough solar field (PTSF) under cloud passages, a novel method which combines a closed-loop thermal hydraulic model (CLTHM) and cloud vector (CV) is developed. Besides, the CLTHM is established and validated based on a pilot plant. Moreover, some key parameters which are used to characterize a typical PTSF and CV are presented for further simulation. Furthermore, two sets of results simulated by the CLTHM are compared and discussed. One set deals with cloud passages by the CV, while the other by the traditionally distributed weather stations (DWSs). Because of considering the solar irradiance distribution in a more detailed and realistically way, compared with the distributed weather station (DWS) simulation, all essential parameters, such as the total flowrate, flow distribution, outlet temperature, thermal and exergetic efficiency, and exergetic destruction tend to be more precise and smoother in the CV simulation. For example, for the runner outlet temperature, which is the most crucial parameter for a running PTSF, the maximum relative error reaches −15% in the comparison. In addition, the mechanism of thermal and hydraulic unbalance caused by cloud passages are explained based on the simulation.     

油砂沥青质对油砂沥青中甲苯残留的影响

利用热重质谱联用仪（TG-MS）分析了三种油砂沥青（印尼油砂沥青、伊朗油砂沥青、加拿大油砂沥青）中的甲苯残留以及油砂沥青质含量对油砂沥青中甲苯残留的影响，并在此基础上，进一步研究了油砂沥青质中的甲苯残留。结果发现，不同油砂沥青中甲苯残留量存在一定差异，其中印尼油砂沥青中的甲苯残留量最多。进一步对沥青质质量分数分别为10%、19%、30%的油砂沥青样品进行热重质谱实验，发现随着油砂沥青中沥青质含量的增加，甲苯的残留量会成倍增加。以加拿大油砂沥青质为例，研究了油砂沥青质对溶剂残留的影响，发现油砂沥青质具有对甲苯分子的夹带能力，导致甲苯分子在超过自身沸点40℃以上才能从沥青质中分离出来。油砂沥青中其他组分的存在也会加剧沥青质对甲苯的夹带作用。此外，研究还发现，在350~650℃时，油砂沥青质可以热解产生甲苯，而且油砂沥青中的沥青质含量越高，热解生成的甲苯越多。     

基于ANSYS的带簧油封径向力分析

提出一种考虑弹簧初应力的油封径向力有限元计算方法,即通过二维轴对称模型实现带簧油封的径向力计算。该模型中通过圆管来等效油封弹簧,并可以实现弹簧初应力现象的模拟;圆管模型的材料属性由2种状态下(弹簧装配在油封上和油封装配在轴上)弹簧的拉力转换得到,转换关系通过试验与仿真相结合的办法获得,最终实现了带簧油封2种状态下的径向力有限元计算。通过径向力测量仪验证计算结果的正确性,同时发现弹簧所产生的径向力并非百分之百转化为油封径向力。     

激励对往复式骨架油封密封性能的影响

为改善往复式骨架油封的泄漏问题,建立油封唇口密封区流体润滑的数值计算模型,模型考虑密封面粗糙形貌以及油封唇口的径向变形,通过求解雷诺方程分析密封区的流体力学特性,获得密封区的油膜厚度和压力分布,并分析激振频率和振幅对密封性能的影响规律。结果表明:随着激振频率的增加,内外行程中密封区的最小膜厚呈先增加后减小的变化趋势,激振频率越大,往复式骨架油封的密封性越差;内外行程中密封区的的最小膜厚随激振振幅的增加呈非线性增加,激振振幅越大,往复式骨架油封的密封性越好。综合考虑,为提高密封效果,往复式骨架油封适用于小频高幅的工作场合。     

Polyoctadecylacrylate (POA) and resin-stabilized asphaltene synergistically improve the flow behavior of model waxy oils

In this paper, the effect of POA PPD together with resin-stabilized asphaltenes on the flow behavior of model waxy oils was investigated through rheological test, DSC, microscopic observation and asphaltenes precipitation test. Compared to the POA or asphaltenes alone, POA/asphaltenes cannot further decrease the wax appearance temperature of oils, but can dramatically decrease the pour point, gelation point, G′, G″ and apparent viscosity of oils. POA molecules can adsorb on the surface of asphaltenes, thus inhibiting the asphaltenes precipitation and forming the POA/asphaltenes composite particles. The composite particles can act as wax crystallization templates and then greatly change the wax crystals' morphology into large and spherical-like, thus improving the waxy oil flow behavior.