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Abstract A CFD modelling study has been undertaken to examine the co-firing of pulverised coal and biomass with particular regard to the burnout of the larger diameter biomass particles. Computations were based on a research combustion facility that replicates an industrial coal-fired power station. Three percent, by mass, of pinewood was blended with a bituminous UK coal, and the effects of the wood particle size and shape on the burnout of the combined wood and coal char were investigated. The effect of varying the devolatilisation and char combustion rate constants for the biomass component in the blend was also investigated. It was concluded that the combustion of small (200 μm) wood particles was rapid but the rate of combustion of larger particles was dependent on their composition, size, and shape.

The Severn Estuary has the world's second largest tide range and a barrage across the estuary, located just seawards of Cardiff in Wales and Weston in the South West England, has been proposed for over half a century, with the objective of extracting large amounts of tidal energy. A Severn Barrage, as previously proposed by the Severn Tidal Power Group (STPG), would be the largest renewable energy project for tidal power generation in the world, if built as proposed, and would generate approximately 5% of the UK's electricity needs. However, concerns have been raised over the environmental impacts of such a barrage, including potential increase in flood risk, loss of intertidal habitats etc. In addressing the challenges of maximizing the energy output and minimizing the environmental impacts of such a barrage, this research study has focused on using a Continental Shelf model, based on the modified Environmental Fluid Dynamics Code (EFDC) with a barrage operation module (EFDC_B), to investigate both the far and near field hydrodynamic impacts of a barrage for different operating scenarios. Three scenarios have been considered to simulate the Severn Barrage, operating via two-way generation and using different combinations of turbines and sluices. The first scenario consisted of 216 turbines and 166 sluices installed along the barrage; the second consisted of 382 turbines with no sluices; and the third consisted of 764 turbines and no sluices. The specification of the sluice gates and turbines are the same for all scenarios. The model results indicate that the third scenario has the best mitigating effects for the far-field and near-field flood risks caused by a barrage and produces the most similar results of minimum water depth and maximum velocity distributions to those obtained from simulating the natural conditions of the estuary, i.e. the current conditions. The results also show that the flow patterns around the barrage are closest to those for the existing natural conditions with minimal slight changes in the estuary. Thus, the results clearly indicate that the environmental impacts of a Severn Barrage can be minimized if the barrage is operated for two-way generation and under the third scenario. Although it appears that the energy output for the third scenario is less than that obtained for the other two scenarios, if very low head (VLH) turbines are used, then the third scenario could generate more energy as more turbines could be cited along the barrage structure. Therefore, the study shows that a Severn Barrage, operating in two-way generation and with 764 turbines (ideally VLH turbines), would be the best option to meet the needs of maximizing the energy output, but having a minimal impact on environmental changes in the estuary and far-field.

For zero‐defect wave soldering of double‐sided and multilayer printed circuit boards, the copper through‐hole‐plating must be impervious to gas generated in the laminate for the period of a few seconds while the solder is molten. The kinetics of the gas evolution during soldering have been related quantitatively to the integrity of the plated copper. This in turn is related to the quality of the electroless copper (evaluated using the backlighting test), the nature and distribution of the catalyst (evaluated using X‐ray photoelectron spectroscopy) and the methods and effectiveness of the hole‐wall preparation (evaluated using scanning electron microscopy). The relevance of laboratory measurements has been confirmed on a wide range of industrial production plating lines.

Even with state of the art forecasting methods, the short-term generation of wind farms cannot be predicted with a high degree of accuracy. In a market situation, these forecasting errors lead to commercial risk through imbalance costs when advance contracting. This situation is one that needs to be addressed due to the steady increase in the amount of grid connected wind generation, combined with the rise of deregulated, market orientated electricity systems. In the presence of imbalance prices and uncertain generation, a method is required to determine the optimum level of contract energy to be sold on the advance markets. Such a method is presented here using Markov probabilities for a wind farm and demonstrates substantial reductions in the imbalance costs. The effect of market closure delays and forecasting window lengths are also shown.

Abstract In this paper, the possibility of applying a Power System Stabilizer (PSS) via the governor-turbine system of a generating unit is studied for both single-machine and multimachine power systems. The results of analysis and simulation show that the conventional exciter-based PSS can be used in conjunction with the modern high-speed governor to suppress low-frequency oscillations in power systems. This arrangement of stabilizer possesses better robustness to the changes of power system operating conditions. Furthermore, in the environment of a multimachine power system, the control of PSS on the governor of every generator can be locally synthesized to stabilize the whole system, PSS design becomes much easier and simpler.

Abstract The housing growth programme could offer an opportunity for accelerating the deployment of decentralised renewable energy systems (DRES) in the UK. The Government hopes to leverage private sector investment into DRES as part of new housing projects. The aim of this paper is to assess whether current regulatory and funding frameworks are sufficient to achieve this. The question is explored by drawing on the experience of developers, local authorities, energy utilities and service companies operating in the largest housing growth region in the UK–Thames Gateway. Their experience suggests that the current low intervention approach will be insufficient to generate the shift required in both industries. In order to be more successful economic and regulatory instruments should focus on producers (house-builders and energy providers) rather than consumers (households). Tighter regulation is needed to ensure that producers have a responsibility to install DRES as part of new developments, to enable connection to the grid, to ensure a sustained financial return from investment and revenue is spent on the expansion of new renewable energy infrastructure. This regulatory framework must be under-pinned by substantial funds focused on producers. Greater intervention is needed if DRES is to be included in new housing development.

Abstract A new method for providing ventilation in large enclosures, which utilizes the principle of ‘selective withdrawal’ of contaminants while ensuring energy-efficiency and allowing a better use of space, is presented in this study. The concept is based on dividing the enclosed space ventilation-wise into separate zones using a combination of horizontal partitions by stratification and vertical partitions by temporary walls. This gives a high degree of flexibility in the use of available space. The relative influence of all the parameters on the flow patterns inside an enclosure is discussed in order to identify the design parameters that should be controlled to apply the technique successfully. An experimental study in a scale model was conducted, which provided a better understanding of the physical processes that occur in such enclosures. The influence of exhaust location on the flow field was studied in particular. It was found that by controlling the position of exhaust the stratification effects are enhanced and maintained at a desired level in order to achieve a successful utilization of the selective ventilation system.

Abstract Analytical and numerical investigation of methane–air lean combustibility limit (LCL) in reciprocal flow filtration combustion reactor was performed. Practically important parameters (heat loss coefficient, reactor length, pressure, particles size, porosity) were varied and corresponding sets of LCL curves were built. Existence of extremum at LCL – gas flow rate function is found. Numerical study shows that the porous media particle size is the most important factor for LCL control. Smaller particles provide lower LCL and reduce steepness of the growing branch of the LCL-gas flow rate function. For the particles smaller than 2 mm the corresponding LCL line goes down monotonously. High pressure in the system provides better LCL, which may be used for stabilization of the reactors operating at near LCL regimes.