No description available.

No description available.

No description available.

No description available.

No description available.

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.