Multi-linear performance model for hybrid (C)PVT solar collectors

A performance model is presented that enables yield predictions of hybrid photovoltaic and thermal (PVT) collectors. It applies for both non-concentrating (PVT) and concentrating (CPVT) systems. The model is based on considerations on energy balance, heat transfer and the dependence of the photovoltaic efficiency on absorber temperature. Similar to the quasi dynamic model for thermal collectors, linear parameterizations of both electrical and thermal power outputs are derived. The respective linear coefficients are obtained from multi-linear regression on solely standard measurement data.The model is applied to measurement data of a CPVT collector to exemplify the procedure and to validate the model. Good agreement of empirically determined collector coefficients with expectations from known parameters is achieved.     

Blends of maleic‐anhydride‐grafted polyethylene with polyethylene for improved cathodic disbondment performance

Buried metal structures such as pipes are usually protected by a coating, often in conjunction with cathodic protection (CP). Whilst this minimizes corrosion, it can also lead to the loss of adhesion between the protective coating and metal structure by a phenomenon called cathodic disbondment (CD). In this study, various medium‐density polyethylene (MDPE) compositions with maleic‐anhydride‐grafted‐polyethylene (MAH‐ g ‐PE) have been formulated to investigate the effect on CD performance, as well as both wet and dry bond strength. The results indicate an improvement in both CD performance and bond strength for all compositions. Differential scanning calorimetry (DSC) and pressure‐volume‐temperature (PVT) experiments are used to characterize the polymer formulations developed and to aid in the understanding of the reasons for such improvement. Energy dispersive X‐ray spectroscopy (EDXS) has been used to obtain surface analysis data on disbonded materials in order to evaluate the failure mode during the CD process. It is found that there may be an optimum loading of the polar functional groups in MDPE necessary for the best CD performance, and that wet adhesion strength (rather than dry) is an important parameter to assess and understand the CD performance of coatings. © 2001 Society of Chemical Industry     

Neuro-Fuzzy Modeling for the Prediction of Below-Bubble-Point Viscosity

Abstract

Accurate prediction of reservoir fluid is one of the important factors that needs to be determined due to it usefulness in fluid characterizations, material balance calculations, and general management of reserves. Below-bubble-point viscosity is one of the important variables that has been determined either experimentally or empirically.

This work focuses on the use of neuro-fuzzy techniques to develop a below-bubble-point viscosity model using 1,693 data obtained from different oil fields in the Niger Delta, Nigeria. The data set was randomly divided into three parts with 56.3% used for training, 18.7% for validation, and 25% for testing. The accuracy of the developed model in this study was compared with some published correlations. The statistical analysis results show that the developed model outperformed existing published correlations.     

AlN单晶的位错腐蚀和红外吸收分析

The defects and the lattice perfection of an AlN（0001） single crystal grown by the physical vapor trans-port（PVT） method were investigated by wet etching, X-ray diffraction（XRD）, and infrared absorption, respectively.A regular hexagonal etch pit density（EPD） of about 4000 cm-2 is observed on the（0001） Al surface of an AlN single crystal.The EPD exhibits a line array along the slip direction of the wurtzite structure, indicating a quite large thermal stress born by the crystal in the growth process.The XRD full width at half maximum（FWHM） of the single crystal is 35 arcsec, suggesting a good lattice perfection.Pronounced infrared absorption peaks are observed at wave numbers of 1790, 1850, 2000, and 3000 cm-1, respectively.These absorptions might relate to impurities O, C, Si and their complexes in AlN single crystals.     

PDS高压物性取样及转样应用分析

介绍PDS并底取样器原理以及现场应用技术，主要分析了使用中遇到的实际问题，如预置压力、油嘴选择、转样以及泡点分析等。总结了PDS的操作实践及取得合格高压物性样品的必要条件。     

单级压缩PVT热泵系统夏季制冷特性实验研究

PVT热泵系统是太阳能热泵与光伏光热(PVT)综合利用技术的结合,具有在同一套系统上分时输出热能、电能和冷量的热电冷三联供的特点,可以满足建筑多样化、分布式的能源需求。本文以单级压缩PVT热泵系统的夏季制冷性能为研究重点,对以PVT组件直接作为热泵系统冷凝器与外界环境进行辐射冷却换热和对流换热的制冷运行模式进行实验研究,论述了系统组成及工作原理、系统数学模型、性能评价方法,并分析了实验系统在不同气象条件下的制冷性能,对系统数学模型理论解进行实验验证。研究结果表明：单级压缩PVT热泵系统在夏季多种气象条件下均可实现制冷模式运行,且制冷性能良好、系统配置简单、长期稳定运行。在夏季夜间晴朗气象条件下,系统平均制冷COP_c为2.8(制冷冻水)和2.3(制冰);在夏季日间阴天工况,系统平均制冷COP_c为2.37(制冷冻水),系统在夜间的制冷性能比日间约高20%。     

直膨式太阳能PVT热泵系统性能仿真及全年运行性能分析

本文对基于直膨式PVT(光伏光热)组件的太阳能热泵系统进行了数学模型的构建及性能仿真,分析了系统在上海地区的全年运行性能。通过直膨式集热/蒸发器将热泵系统与光伏组件相耦合,吸收光伏组件在工作时产生的废热,在降低光伏组件工作温度、提升组件发电效率的同时,提升了热泵循环的蒸发温度,从而改善了热泵系统的运行性能。基于能量平衡与集热/蒸发器换热特性建立了仿真模型,并与实验结果进行对比,最大误差为6.2%。在上海地区的气温、辐照条件下对系统运行进行了逐日的模拟。模拟结果表明：当冷凝温度为55℃时,系统COP在2.67～9.06之间波动,全年平均COP可达5.47;系统全年平均蒸发温度为18.34℃,平均得热效率为100.06%;PVT组件的全年平均工作温度比光伏组件下降20.21℃,可带来11.80%的全年发电增益。     

附加碳源对SiC单晶生长过程的影响

研究了用物理气相传输（PVT）法制备SiC单晶的过程中附加碳源对晶体生长速度及缺陷的影响，并将活性炭与SiC粉末一起加入到石墨坩埚中进行晶体生长。用XRD分别测定了晶体生长前后坩埚与活性炭的石墨化度，并用光学显微镜观察了晶体中的缺陷。结果表明，随晶体生长过程的进行石墨坩埚的活性降低，直接导致晶体生长速度减慢，并使籽晶表面Si液相形成的可能性增大，与Si液相相关的缺陷增多。活性炭的加入给生长过程提供了充足的碳源，提高了晶体的生长速度，并抑制了籽晶表面Si液相的形成，从而降低了与Si液相相关缺陷出现的几率。     

松辽盆地古龙凹陷凝析气藏判断及其分布

针对古龙凹陷地区缺乏高压PVT相图的情况,首先通过试油成果中气油比的特征区分出油藏和气藏两种类型,然后在油气配方合成井流物的摩尔组成基础上,借助于Φ值法、Z值法和PR状态方程计算PVT相图进行综合分析,判断出古109井区葡萄花油层是一个带油环中等凝析油含量的凝析气藏.根据凝析气藏的成藏机理,预测了该区凝析气藏分布的有利区带.