New strategies for separations through reactions

Separations through reactions can provide reliable and economically viable alternatives to established methods of separation, particularly for close boiling substances. New strategies in ‘Dissociation Extraction’ and ‘Dissociation Extractive Crystallization’ for separation of close boiling acidic/basic mixtures have been highlighted. Separations with aqueous solutions of hydrotrope and aqueous micellar solutions have been brought out. Separations by membranes with facilitated transport is potentially attractive. This paper is dedicated to Dr L K Doraiswamy on his sixtieth birthday.     

Optimal Control of Solar Sludge Dryers

Optimal control (OC) methodology is used to develop a control policy for a batch-operated solar sludge dryer with ventilation as the dominant control. Batch performance criteria and instantaneous optimization criteria are developed for two economic environments: quota limited and capital limited. The general formulation, as well as simplifications resulting from the multiplicative form of the evaporation (drying) rate model, are presented. The multiplicative form results in a single constant number, called here “control intensity,” which is used to guide the on-line control decisions. These decisions turn out to be independent of the dry solids content (DSC) of the sludge. Further simplification, by assuming a strictly constant weather, is used to demonstrate the general effects of the economic and physical (weather) environment on the solution.

The OC approach is used to address, via simulation under realistic weather conditions, several design, operation, and pricing problems. In particular, the following have been considered: sizing of the ventilation fans, determination of a fair fee for sludge disposal, finding the best final DSC, and evaluating the effect of the price of electricity. Regarding the particular location represented by the data, it has been shown that the installed capacity of the ventilation fans should be increased and that there seems to be sufficient economic incentive for solar drying.     

Characteristics of the reactive distillation column with a novel internal

A new catalyst loading method, in which catalyst particles are packed in a reactor with a novel internal, has been studied by measuring pressure drop, RTD, liquid holdup and mass transfer. It can be inferred from experimental results that the internal changes the conventional gas and liquid counter-current flow into a new cross-current flow, so the problems of excessive pressure drop and “flooding” are avoided. When pressure drop, liquid holdup, RTD and mass transfer coefficient are similar, the catalyst loading fraction of the new method is much higher than that of conventional methods. Furthermore, the reactive distillation reactor with the novel internal has advantages such as simple structure, low operating cost, and convenience for installation and removal of the catalyst.     

Characterization of CuInS2 thin films for solar cells prepared by spray pyrolysis

We have made a study of the chemical composition, the electrical, the optical and the structural properties of polycrystalline CuInS₂ thin films prepared by spray pyrolysis to be used for thin film solar cells. These films were deposited starting from aqueous solutions with different chemical compositions ([Cu]/[In] and [S]/[Cu] ratios) and at different substrate temperatures. In all cases, the material is p-type with grains preferentially oriented in the (112) direction of the sphalerite structure. The electro-optical properties show a very strong dependence on the [Cu]/[In] ratio in the solution. Films with copper excess have smaller resistivity and better crystallinity than those which are stoichiometric or have indium excess. The results obtained in this work show the possibility of having CuInS₂ thin films with a wide range of resistivity, a fact that could be important for making solar cells based on this material.     

The reality of living in passive solar homes: A user-experience study

This paper presents a study of a user-experience survey about living in passive solar homes. It was carried out at the Energy Park located in the western part of Milton Keynes. The survey focuses on the reality of living in passive solar homes as perceived or experienced by the occupant. It is hoped that the findings would come to bear on strategic passive solar design decisions that would address the improvement of the well-being of the occupant.. The survey is aimed at assessing user satisfaction with the overall performance of their homes as well as a study of some of the problems that are believed to be common in passive solar housing.Results from the survey seem to indicate that the majority of those who buy passive solar homes are motivated to do so by a desire for thermal comfort at low cost. The building aesthetics is the second most important factor, showing that passive solar home lovers are also conscious of the quality of the architectural design. The overall performance of passive solar homes in this study, with regard to thermal and visual comfort, seems to be generally satisfactory. Statistical analysis showed some significant association between some important environmental design parameters.     

Energy use in the life cycle of conventional and low-energy buildings: A review article

A literature survey on buildings’ life cycle energy use was performed, resulting in a total of 60 cases from nine countries. The cases included both residential and non-residential units. Despite climate and other background differences, the study revealed a linear relation between operating and total energy valid through all the cases. Case studies on buildings built according to different design criteria, and at parity of all other conditions, showed that design of low-energy buildings induces both a net benefit in total life cycle energy demand and an increase in the embodied energy. A solar house proved to be more energy efficient than an equivalent house built with commitment to use “green” materials. Also, the same solar house decreased life cycle energy demand by a factor of two with respect to an equivalent conventional version, when operating energy was expressed as end-use energy and the lifetime assumed to be 50 years. A passive house proved to be more energy efficient than an equivalent self-sufficient solar house. Also, the same passive house decreased life cycle energy demand by a factor of three – expected to rise to four in a new version – with respect to an equivalent conventional version, when operating energy was expressed as primary energy and the lifetime assumed to be 80 years.     

热镀锌渣真空蒸馏回收锌

在钢件热镀锌过程中，产出约占锌总量１０％的热镀锌渣，渣中含锌和少量铁，铅，铜，铝等杂质。用直空蒸馏方法从热镀锌渣中提取锌；具空度１．３３×１０＾２－１．３３×１０＾３Ｐａ，温度９００℃，作业时间１１ｈ／炉，电耗约２０００度／ｔ锌，试验表明，锌的直收离可达８４％，为热镀锌渣中锌的回收提供了一英经济而合理的方法。     

甲醇与碳酸二甲酯共沸液的分离研究进展

综述了DMC-CH_3OH二元共沸液的各种分离方法。讨论了共沸精馏和萃取精馏的工艺流程。     

萃取精馏回收环己烷的双组分溶剂的研究

在研究萃取精馏分离回收环己烷的单溶剂的基础上，研究了双组分溶剂。当剂油比为7:1时，环己醇和四甘醇双组分溶剂可以将正庚烷对环己烷的相对挥发度由单溶剂时的小于1提高到1．11；将2，3—二甲基戊烷对环己烷的相对挥发度由单溶剂时的小于1．07提高到1．21。用该溶剂在小型萃取精馏实验装置上运行，结果表明，环己烷的纯度为98．5％，收率为80％。     

原木板材的窑式干燥

本文综述了canterbury大学近年来关于新西兰木材窑式干燥的研究。有些硬木单纯窑式干燥是困难的,但利用太阳能窑式风干则有可能;轮回操作可以减小干燥应力从而减小产品性能的退化程度。种植生产为主的软木干燥较容易,从经济考虑应采用高温干燥,以减少干燥时间。高温操作时对流传递显得相当重要。实验表明,当空气流过板面时,不同点处的传质系数有显著差异。湿分在木板中移动的模型可假定为:随着干燥进行蒸发面向中心退缩。但心材和边材的行为有所不同:边材中的水份可在相邻脉管间迁移,但在心材中则不可能。正是这种差异导致干燥时间和干燥温度曲线不同。