A Synthesis of Thermodynamic Models Unifying Traditional and Work-Driven Operations with Heat and Mass Exchange

A novel trend in the theory of thermodynamic limits for energy convertors and traditional heat and mass exchangers is analyzed, where certain special controls called, the Carnot control variables, play a common role. In terms of these controls an expression for the lost work has the same form in irreversible energy convertors and in traditional processes of purely dissipative transport. For sequential-type equipment of a finite size, enhanced limits are obtained for the energy production or consumption. Formal models of simplest energy convertors and characteristics of endoreversible operations are particularly lucid in terms of the Carnot controls. Progress in the theory of energy generation problems is achieved; examples of applications are outlined. Efficiency decrease caused by dissipation and finite rate bounds are estimated for work released from an engine or work added to a heat pump. It is shown that a simplification in the analysis of energy limits in complex thermal operations is achieved when Carnot controls are applied. Extensions involve mass transfer problems and a finite-rate counterpart of classical available energy (exergy).     

On decentralised control of non-linear interconnected systems

The asymptotic stabilisation problem of a class of large-scale interconnected systems is considered, where the non-linear interconnections between subsystems satisfy quadratic constraints that are functions of the whole system's state vector. A decentralised combined observer-controller compensator is proposed and analysed, where the subsystems’ state vectors are estimated using local sliding mode observers. The closed-loop system driven by the proposed decentralised compensator is guaranteed to be asymptotically stable subject to two conditions that are easily verifiable. Simulation results illustrate the effectiveness of the proposed decentralised combined observer-controller compensator.     

An Eco‐innovation Case Study of Domestic Dishwashing through the Application of TRIZ Tools

The benefits of applying a structured method such as TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch: the Russian theory of inventive problem solving) to Eco‐innovation are examined through use of two problem‐solving tools from TRIZ in an Eco‐innovation case study. A novel problem hierarchy model has been integrated to help identify the systems and sub‐systems level innovations required for Eco‐innovation. The benefits and shortcomings of the TRIZ tools, and the potential contribution of the problem hierarchy model in the innovation process are discussed.     

HIGHLIGHTS OF IDS'92

ABSTRACT

High energy consumption and increasing consumers interest in new products are two problems worthy of note in the drying of food. Difficulties in producing high-quality food and degrading transformations of the material during drying are mentioned. The kinetics of quality degradation due to drying is described. The role of water activity in maintaining product quality is emphasized. Examples of drying methods and tendencies toward a reduction in quality degradation of dried food products are shown.     

Equipment selection and justification through total productivity model

Traditional methods of economic analysis to justify equipment selection and use are based on several methods such as the Net Present Value, Break-Even Analysis, Pay-Back Period, Return on Investment, among others. However, with the introduction of automation, Flexible Manufacturing Systems (FMS), and Computer Integrated Manufacturing Systems (CIMS), such economic analyses have often resulted in decisions that management did not like to support but did not have much choice to avoid on account of pressure from manufacturing engineers, design engineers and others in the operations areas. The real problem of equipment selection and justification lies in the methodologies used.

This paper presents a unique approach to equipment justification by applying Sumanth's TOTAL PRODUCTIVITY MODEL, whereby the anticipated impact of the proposed equipment on profitability is assessed from the point of total productivity and the five partial productivities. Then, only if the equipment increases the total productivity level beyond its break even point, the equipment is selected or justified.

This method offers a non-traditional approach to justifying and selecting equipment in all types of environment. A numerical example is presented by using LOTUS 1-2-3^TM on an IBM PC. Advantages and limitations to this approach are discussed to provide a balanced perspective on the important issue of equipment selection and justification.