Uniform Cr<Superscript>2+</Superscript> doping of physical vapor transport grown CdS<Subscript>x</Subscript>Se<Subscript>1−x</Subscript> crystals

The Cr²⁺ doped CdS_0.8Se_0.2 crystals were grown by the vertical, self-seeded, physical vapor transport (PVT) technique. Good quality, crack- and inclusion-free single crystals were grown with an average Cr²⁺ concentration of 5 × 10¹⁸ cm⁻³. Different source-to-tip distances were used to improve the segregation coefficient (Cr_crystal/Cr_source) of the grown crystals. It was observed that lowering the source-to-tip distance increases the segregation coefficient dramatically. With a 2-cm source-to-tip distance, good quality crystals were grown with uniform Cr²⁺ concentration throughout the ingot. The segregation coefficient was found to be ∼0.85. The composition of the crystals was also found to be fairly uniform along the length and across the diameter.     

高压下正庚烷—醇二元液态系统PVT性质的研究

利用装有光学玻璃窗的高压釜测量了高压下正庚烷分别与乙醇、正丙醇、正丁醇及正戊醇等液体混合物的ＰＶＴ数据。实验采用“直接法”，压力达到近９０ＭＰａ，温度范围为２９８～３７３Ｋ。上述后三个系统高压下的ＰＶＴ数据尚属首次测量。根据实验结果计算出过量摩尔体积和等温压缩率，同时加以讨论，并利用Ｔｈｏｍｓｏｎ方程对上述系统的ＰＶＴ数据进行计算，发现与实验结果符合情况良好。     

MATLAB软件在原油高压物性参数预测中的应用

一个油田或区块,可以通过井底取样或重组复配的方法获得高压物性参数,然后通过回归分析技术建立地面原油物性及高压物性参数之间的经验公式,以此关系式预测其它井及不同压力温度条件下的高压物性。这里采用已有高压物性经验公式的形式,使用MATLAB软件数理统计工具箱中的非线性回归函数nlinfit给出了大庆外围各油田高压物性参数预测公式,并对比了使用新系数的计算公式和使用原系数的计算公式的平均误差和平均相对误差,结果表明新系数计算结果优于原系数,应用新公式预测大庆外围各油田高压物性参数,能够得到比较可靠的结果。     

Application of the PR-EOS with C7+ Splitting to Model Fluid Properties in a Large Two-Phase Petroleum Reservoir

The use of equations of state (EOS) to model fluid properties is necessary in order to have an internally consistent set of PVT properties, which is essential, especially, when it is desired to use compositional simulators to model two-phase reservoirs. In this article, the 3-parameter Peng-Robinson equation of state along with single carbon number (SCN) splitting of the C₇₊ fraction are used to model a major onshore reservoir in Abu Dhabi that has horizontal and vertical fluid properties variations. Extensive screening and checking of PVT data of the field was necessary to develop this model. Also, extensive verification of the developed model was accomplished by comparing its results to data external to the model. Results of this article indicate the capability of using multiple well PVT analysis within the three-parameter Peng-Robinson EOS to model complex two-phase reservoirs such as this one. We describe the process of building up the model and the challenges involved in performing this task, which include proper selection of representative experimental data to build the model, along with extensive screening and data quality these data, and the model verification so that we have the confidence that one EOS model that can predict the reservoir fluid PVT properties.     

A cross-layer SER analysis in the presence of PVTA variations

As the technology scaling enters into the nanoscale regime, soft errors become one of the major challenging issues for VLSI chips. Susceptibility to soft error is even becoming more severe in the presence of workload-dependent Process, Voltage, Temperature, and Transistor Aging (PVTA) variations. In this paper, we propose a systematic cross-layer methodology to model and analyze the impact of different abstraction layers on the PVTA variations and in turn on the susceptibility of processors to soft error. To do so, the workload is divided into several fine-grained timing windows. Based on a top-down profiling approach, the effects of each window is projected into the circuit-level model of the processor in order to extract PVTA profiles of “each cell” in the circuit. Finally, at circuit-level, an “instance-based” simulation flow is exploited to capture both spatial and temporal PVTA-aware Soft Error Rate (SER) variations within/across applications for every functional block of the processor. The simulation results for various ITC’99 benchmark circuits and the LEON3 processor running different benchmark applications show that disregarding PVTA information results in significant error in the estimated SER.     

高承压酸溶性堵漏剂ZC6—6的研制与应用

针对钻井工程中同一裸眼井段地层压力系数相有差悬殊、高低压层交替出现引起的高压差性井漏和“漏储同层”型井漏的油气保护问题，研制成功了能大幅度提高漏层承压能力并能酸化解堵的高承压酸溶性固化堵 漏剂ZC6-6。该堵剂养护24h的抗压强度≥12MPa ,凝固体的常温酸溶率≥90%。现场易配制，施工方便，使用证明，可提高漏层承压能力0.4g/cm∧3以上当量钻进井液密度。该堵剂对产层和非产层进漏均可适用，也可用于修井作业中的井漏。     

Hybrid photovoltaic and thermal solar-collector designed for natural circulation of water

The electricity conversion-efficiency of a solar cell for commercial application is about 6–15%. More than 85% of the incoming solar energy is either reflected or absorbed as heat energy. Consequently, the working temperature of the solar cells increases considerably after prolonged operations and the cell’s efficiency drops significantly. The hybrid photovoltaic and thermal (PVT) collector technology using water as the coolant has been seen as a solution for improving the energy performance. Through good thermal-contact between the thermal absorber and the PV module, both the electrical efficiency and the thermal efficiency can be raised. Fin performance of the heat exchanger is one crucial factor in achieving a high overall energy yield. In this paper, the design developments of the PVT collectors are briefly reviewed. Our observation is that very few studies have been done on the PVT system adopting a flat-box absorber design. Accordingly, an aluminum-alloy flat-box type hybrid solar collector functioned as a thermosyphon system was constructed. While the system efficiencies did vary with the operating conditions, the test results indicated that the daily thermal efficiency could reach around 40% when the initial water-temperature in the system is the same as the daily mean ambient temperature.     

The performance of PV‐t systems for residential application in Bangkok

This paper focused on the performance of photovoltaic‐thermal (PVT) systems working in Bangkok for residential applications. The PVT system is one which produces both electricity and low temperature heat at the same time. This paper investigated the performance of PVT systems that use different types of commercial solar PV panels. The characteristics of the PV panels were used as input parameters in the simulation. Each system comprises 2 m² of PVT collector area. Water draw patterns are those with a typical consumption of medium size houses in Bangkok, and the measured monthly average city water temperature of Bangkok has been used to estimate the energy output. The results show that the optimum water flow rate is 20 kg/h for all types of PVT collectors and the effect of water flow can improve the cell efficiency of PV cells. Moreover, the total energy output from the PVT collectors, which had glass covers is very significantly higher than those without one. The c‐Si PVT panel gave the best performance with the highest rate of primary energy reduction. The payback time of each system is 6.4, 11.8, and 13.4 years for a‐Si, mc‐Si, and c‐Si types of PVT system, respectively. This investigation concludes that from the viewpoint of system performance, c‐Si PVT is the most promising type than whereas from the viewpoint of economy, a‐Si PVT has the fastest payback time. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance evaluation of a hybrid photovoltaic thermal double pass facade for space heating

This paper presents the performance evaluation of a hybrid photovoltaic thermal (Semi transparent PVT) double pass facade for space heating. The thermal model has been developed by using the energy balance equations of the proposed hybrid photovoltaic thermal double pass facade under quasi-steady state condition. Numerical computations have been carried out for the composite climate of New Delhi, India. An analysis has been carried out to calculate annual energy and exergy gain for the hybrid photovoltaic thermal double pass facade. On the basis of numerical results it has been observed that the annual thermal and electrical energy are 480.81 kWh and 469.87 kWh respectively. The yearly overall thermal energy generated by the system has been calculated as 1729.84 kWh. It is also observed that the room air temperature increases by 5-6 °C than the ambient air temperature for a typical winter day.     

New Empirical Correlations for Predicting Crude Oil Properties

Abstract

Pressure–volume–temperature (PVT) properties of crude oil are essential parameters used for prediction of fluid flow both in porous media and through transmission pipelines. Whenever laboratory works are absent, the engineer should use regionally developed correlations. A large portion of all crude oil resources is located in the Persian Gulf countries, and they have more or less similar API ranges and acidities, so that any empirical PVT correlation based on data from one region can adequately predict the behavior of others in this large geological basin. In this study, a new set of black oil–type correlations for bubble point pressure (P_b), solution gas–oil ratio (GOR; R_s), and formation volume factor (Bo) is proposed based on more than 400 Iranian crude oil PVT lab data. Moreover, previous works were reviewed, most of which were not suitable to model Iranian crude PVT behavior. Although the new correlations are developed over Iranian crudes, they can be used for prediction over any crude oil with similar compositional properties (API and acidity). Then the accuracy of these correlations is compared with the newly presented set and the superiority of this work for predicting those parameters is demonstrated.