An examination of the Throughflow of Nucleating Steam in a Turbine Stage by a Time-Marching Method

The paper describes a theoretical treatment for nucleating throughflow of steam in a turbine stage. The conservation equations governing the overall behaviour of the fluid are combined with those describing droplet behaviour and treated by a time-marching method. The computer program developed has been applied to some test cases and comparisons are presented between solutions allowing for non-equilibrium effects and those in which steam has been assumed to remain in thermodynamic equilibrium.

Optimum Design of Radial-Flow Impellers

The paper presents a procedure of computer aided design of high-speed impellers. The configurations are obtained using programs for the strength under the influence of centrifugal force within given constraints. The method provides a tool for optimizing stresses at an early design stage.

A Comparison of the Application of ‘Energy from Municipal Solid Waste’ Technology in Three Countries—the United Kingdom, Sweden and Canada

The United Kingdom, Sweden and Canada are participants in an International Energy Agency programme designed to co-ordinate R and D activity on energy from waste (EFW) technologies. The scope and content of the individual national R and D programmes are a direct result of the different institutional, economic and environmental factors that govern application of such technologies in each country. A description of these factors is given together with an assessment of their influence in shaping the existing and likely future role of landfill gas, refuse-derived fuel and mass incineration in each country.

Thermoeconomic Optimization of a Ventilation Air Heater in a Backpressure Combined Heat and Power Plant

In this paper a method of optimization of plant components is demonstrated for the case of a ventilation air heater in a backpressure combined heat and power (CHP) plant. The method, known as thermoeconomic optimization, combines the concepts of exergy analysis with those of economic analysis. The optimization is carried out in two stages. First the heat-exchanger geometry is optimized for a range of different fixed heat-transfer areas using the trade-off between irreversibility due to pressure losses and that due to heat transfer over a finite temperature difference. In the second stage the economically justified cost of the heat-exchanger is determined using a version of thermoeconomic optimization known as the structural method. The concept of the coefficient of structural bonds is discussed and its use in structural investigation and thermoeconomic optimization is explained. Potential for further improvement in the plant efficiency through optimization is discussed with reference to a diagram of exergy flows and irreversibility rates known as the Grass-mann diagram.

Observations of Experimental Research on Oscillating Linear Drives for Small Piston Compressors

Electric drives provided with an oscillating reluctance or synchronous linear motor and intended to be used in small piston compressors are inherently electromechanical systems. Exclusively electronic control of the drives, based upon special inductance or capacitive methods of measurement of the clearance volume of the driven compressor, enables automatic regulation of the clearance volume to reach the required nominal value or its control, depending upon superior automatic regulation of the output pressure difference, of flow volume (in air compressors) or of the reference temperature of the cooled place (in refrigerating compressors) to the required value. The long-term experimental investigation of research prototypes with the compressors with both types of finely tuned block mechanisms of linear motors of both types enables present-day knowledge to be presented concerning the behaviour and operating and advantageous properties of the developed systems. This experimental research confirmed the favourable influence of the simplified design of the compressors and of electronic control upon the improvement and new possibilities in the construction and also in the application of the compressors.

The Potential of the Stirling Cycle Heat Pump

An important potential application of the electrically driven Stirling cycle heat pump is in the field of industrial waste heat recovery. Here the temperatures and temperature lifts required are often outside the scope of existing types of heat pump. What has to be ascertained is whether the Stirling cycle heat pump can achieve a sufficiently high coefficient of performance. In the paper this question is examined by the use of a theoretical model. The model is first checked against measured results from an actual Stirling heat pump which has been built and tested, but which was of low COP. It is shown that for a temperature lift of WOK, it should be possible to construct a heat pump with a COP of about 3.5. It is also shown that under these conditions, the maximum attainable specific output of heat would approach 1 J/cycle cm3 of piston displacement.

High-Speed Photography of Fuel Spray and Combustion Events in a Production Diesel Engine and Combustion Bomb

The endoscopic high-speed combustion photography technique was used on a four-cylinder Perkins engine to investigate spray formation and combustion events under different engine running conditions. Some tests were also carried out in a fixed-volume combustion chamber (bomb) using conditions similar to those of the engine. The major advantage of using this rig was that each parameter could be varied independently. Spray formation, penetration rate and evaporation were studied in detail. Ignition delay times were established and the location of the start of combustion was identified. Finally, in the analysis of the results the most important factors affecting combustion in a direct injection (DI) diesel engine were outlined.

Calculation of the Flow in a Sector of an Annular Combustor

Calculations have been made of the isothermal flow field within a sector of an annular combustion chamber representative of the type to be found in small gas turbines. The complex combustor geometry is described using a Cartesian finite difference mesh within which the physical domain boundaries are represented in a piecewise linear fashion. The k-s turbulence model is used to describe turbulent transport. Overall the calculated and measured flow fields are found to be in reasonable agreement and in the primary zone measured velocity profiles are reproduced to within an acceptable accuracy.