Drying is one of the most energy intensive operations of the chemical industry and accounts for about 6% of the total energy used by U. K. industry and about 2.5 of the overall energy demand of the U.K. Measurements taken on a typical industrial tumble dryer confirmed that generally convective dryers operate at thermal efficiencies less than 4 and that over 5Y of the energy input is lost as sensible heat content of the moist exhaust air. Any significant improvement in the thermal performance of dryers would therefore require a means of gainfully recovering the heat lost in the exhaust air. Some conventional heat recovery methods have been considered. Recirculation of exhaust air was shown to improve thermal efficiency but at the cost of reduced drying rates. Heat recovery by heat exchange was found unattractive because very large heat exchange surface areas would be required. A new type of adsorption heat pump (AHP) which may be operated either as a temperature swing cycle (TSC) or a pressure swing cycle (PSC), has therefore been proposed here for heat recovery from dryers. An experimental rig was built and used to investigate the adsorption of moisture on silica-gel in a 1.5 m. high, 0.25m. diameter column under conditions that simulate an industrial dryer, including high temperatures and humidities. Correlation of the experimental data led to the derivation of a polynomial function, similar to the system equilibrium equation, which relates the breakpoint capacity of the adsorbent to the breakpoint bed relative humidity. This function was used to develop a new theoretical model for predicting the performance of the proposed heat pump dryer. The predictions of this model enabled similar predictions obtained from two other models synthesized from various proposals put forward by other investigators previously to be tested against experimental results. This new model was found to be the most appropriate for the conditions encountered and was therefore considered to be the most suitable for predicting the performance of the adsorption heat pump drying system. Theoretical predictions based on this model indicate that the heat pump drL-er may be attractive for low temperature ( <1000C) drying. Under high temperature drying conditions low thermal efficiencies and unfavourably large adsorption bed size requirements make the heat pump unattractive.

This thesis is concerned with feasibility of reducing the energy requirement for mtilticomponent distillation processes. Four systems of four component ideal mixtures are considered, using for each system two degrees of recovery (95% and 99.5%) and two configurations I and lI. A mathematical model has been developed to predict the minimum energy sequence for four component mixtures. Because of the difficulties in solving the equations a graphical method is devised to deal with the problem. To develop this method the concept of pseudo-components is invoked, where a 'pseudo-component' is defined as one having predetermined values of the properties required for the design analysis, e.g. K-values, vapour and liquid enthalpies. A prediction design method has been developed for four component ideal systems which enables the optimal sequence to be related for any type of feed, different degree of recoveries and a set of relative volatilities. Energy integration is considered between reboilers and condensers only and then between intermediate heaters and coolers at the pinch points below and above the feed plate, respectively. The concept of non-ideality is introduced. Nonideal systems often occur e.g.industrially significant mixture for such as Ethanol/Water. Their non-ideality makes them energy intensive usually because of the high reflux ratio required. No general solution is possible but two real mixtures are considered, Acetone/Cumene /Phenol and Ethanol/Water. It is shown that the engineering techniques discussed earlier can be used to produce significant savings in energy requirement for the two systems. These techniques are also applied to an industrial system. The first is the separation of light hydrocarbons, in a stabilizer, C3/C4 splitter and Gasoline Splitter. The mixture is nearly ideal in its vapour-liquid equilibrium relationships and again it is shown that considerable energy savings are possible. The conclusions of the work are summarised and suggestions for further studies in this field are provided.

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This study is concerned with the identification and utilisation of design solutions for improving the thermal environment of residential buildings in hot dry climates in general and the hot arid zone of Iran in particular. The influence of various energy conservation options on energy use in a prototype house has been analysed using the ESP dynamic computer simulation program. The research was aimed at providing a range of design guidelines for use in the process of building design by builders, architects and engineers. It also suggests programs relying on occupancy behaviour such as; thermostat settings or operating windows. The recommended design solutions are among those which can be obtained economically through the architectural application of commonly available construction materials and skills whilst also being appropriate in the socio-economic context in which the design and use of buildings take place. The effect of parameters such as; thermal mass and insulation, surface characteristics, orientation, window design, shading and environmental control strategies on the thermal performance of the prototype house has been investigated. Energy and comfort have been used as indicators of performance.

The rapid housing and building development in the Dammam region of Saudi Arabia has transformed the region into a progressive urban area. The contemporary buildings which have spread all over the region in a short period have failed to provide acceptable comfort conditions inside the house, leading to the widespread use of mechanical cooling systems. The combination of poor thermal design and the rise in electricity prices has resulted in high annual fuel bills for running the air conditioning systems. This study investigates the potential for energy conservation in residential buildings in Dammam region. It aims to identify the problem of high energy consumption in contemporary buildings and to study the relationship between the energy used and the thermal performance of the building. This study reviews the socio-economic characteristics of Dammam region's inhabitants and the traditional and contemporary building materials cooling systems used in the region. It also presents a survey analysis of 500 houses and provides a thermal comparison and assessment of six case study houses. A computer model has been developed and validated by the author to predict the annual amount of energy used in cooling the house. This model has been used to. predict the various energy savings that can be achieved by modifying the building envelope • elements and using lower U-values. Finally, some recommendations have been derived from the analysis.

With the increased loading and exploitation of the power transmission system and also due to improved optimised operation, the problem of voltage stability and voltage collapse attracts more and more attention . A voltage collapse can take place in systems or subsystems and can appear quite abruptly. Continuous monitoring of the system state is therefore required. The cause of the 1977 New York black out has been proved to be the reactive power problem. The 1987 Tokyo black out was believed to be due to reactive power shortage and to a voltage collapse at summer peak load. These facts have strongly indicated that reactive power planning and dispatching play an important role in the security of modern power systems. A proper compensation of system voltage profiles will enhance the system securities in the operation and will reduce system losses. In this thesis, some aspects of reactive power dispatch and voltage control problem have been investigated. The research has focused on the following three issues: Firstly, the steady-state stability problem has been tackled where, a voltage collapse proximity indicator based on the optimal impedance solution of a two bus system has been generalised to an actual system and the performance of this indicator has been investigated over the whole range (stable and unstable region) to see how useful this indicator can be for an operator at any operating point. Then we went further to implement a linear reactive power dispatch algorithm in which this indicator was used for the first time to attempt to prevent a voltage collapse in the system. Secondly, a new efficient technique for N-1 security has been incorporated aiming at either maximising the reactive power reserve margin for the generators or minimising active power losses during normal as well as outage conditions (single line outage) .The reactive power redistribution after an outage is based on the S-E graph adopted by Phadke and Spong[72].Thirdly, the dispatch (N-1 security excluded) has been incorporated on line in the O.C.E.P.S. control package to improve the quality of the service and system security by optimally controlling the generator voltages (potentially the reactive control system is able to control transformers, switchable capacitors and reactors). A new function called load voltage control (similar to the load frequency control function) has been introduced to allow smooth variation of the reactive control signals towards their targets.

The present day digital computing resources are overburdened by the amount of calculation necessary for power system dynamic simulation. Although the hardware has improved significantly, the expansion of the interconnected systems, and the requirement for more detailed models with frequent solutions have increased the need for simulating these systems in real time. To achieve this, more effort has been devoted to developing and improving the application of numerical methods and computational techniques such as sparsity-directed approaches and network decomposition to power system dynamic studies. This project is a modest contribution towards solving this problem. It consists of applying a very efficient sparsity technique to the power system dynamic simulator under a wide range of events. The method used was first developed by Zollenkopf (^117) Following the structure of the linear equations related to power system dynamic simulator models, the original algorithm which was conceived for scalar calculation has been modified to use sets of 2 * 2 sub-matrices for both the dynamic and algebraic equations. The realisation of real-time simulators also requires the simplification of the power system models and the adoption of a few assumptions such as neglecting short time constants. Most of the network components are simulated. The generating units include synchronous generators and their local controllers, and the simulated network is composed of transmission lines and transformers with tap-changing and phase-shifting, non-linear static loads, shunt compensators and simplified protection. The simulator is capable of handling some of the severe events which occur in power systems such as islanding, island re-synchronisation and generator start-up and shut-down. To avoid the stiffness problem and ensure the numerical stability of the system at long time steps at a reasonable accuracy, the implicit trapezoidal rule is used for discretising the dynamic equations. The algebraisation of differential equations requires an iterative process. Also the non-linear network models are generally better solved by the Newton-Raphson iterative method which has an efficient quadratic rate of convergence. This has favoured the adoption of the simultaneous technique over the classical partitioned method. In this case the algebraised differential equations and the non-linear static equations are solved as one set of algebraic equations. Another way of speeding-up centralised simulators is the adoption of distributed techniques. In this case the simulated networks are subdivided into areas which are computed by a multi-task machine (Perkin Elmer PE3230). A coordinating subprogram is necessary to synchronise and control the computation of the different areas, and perform the overall solution of the system. In addition to this decomposed algorithm the developed technique is also implemented in the parallel simulator running on the Array Processor FPS 5205 attached to a Perkin Elmer PE 3230 minicomputer, and a centralised version run on the host computer. Testing these simulators on three networks under a range of events would allow for the assessment of the algorithm and the selection of the best candidate hardware structure to be used as a dedicated machine to support the dynamic simulator. The results obtained from this dynamic simulator are very impressive. Great speed-up is realised, stable solutions under very severe events are obtained showing the robustness of the system, and accurate long-term results are obtained. Therefore, the present simulator provides a realistic test bed to the Energy Management System. It can also be used for other purposes such as operator training.

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