Coupling CFD and visualisation to model the behaviour and effect on visibility of small particles in air

The use of computational fluid dynamics (CFD) and lighting simulation software is becoming commonplace in building design. This study looks at a novel linkage between these two tools in the visualization of droplets or particles suspended in air. CFD is used to predict the distribution of the particles, which is then processed and passed to the lighting simulation tool. The mechanism for transforming CFD contaminant concentration predictions to a form suitable for visual simulation is explained in detail and an example presented which demonstrates this linkage. The CFD-visualisation simulations described in this paper have applications in both automotive and fire safety through the modelling of fog and smoke respectively. Historically, smoke and fog effects have been rendered in images with no attempt at modelling physical reality. The novelty of the work presented in this paper is that, for the first time, an attempt is made to model both the fluid mechanics and optical physics of small particles suspended in a primary fluid

Specifications for modelling fuel cell and combustion-based residential cogeneration device within whole-building simulation programs

This document contains the specifications for a series of residential cogeneration device models developed within IEA/ECBCS Annex 42. The devices covered are: solid oxide and polymer exchange membrane fuel cells (SOFC and PEM), and internal combustion and Stirling engine units (ICE and SE). These models have been developed for use within whole-building simulation programs and one or more of the models described herein have been integrated into the following simulation packages: ESP-r, EnergyPlus, TRNSYS and IDA-ICE. The models have been designed to predict the energy performance of cogeneration devices when integrated into a residential building (dwelling). The models account for thermal performance (dynamic thermal performance in the case of the combustion engine models), electrochemical and combustion reactions where appropriate, along with electrical power output. All of the devices are modelled at levels of detail appropriate for whole-building simulation tools

Urban wind energy conversion: the potential of ducted turbines

The prospects for urban wind power are discussed. A roof-mounted ducted wind turbine, which uses pressure differentials created by wind flow around a building, is proposed as an alternative to more conventional approaches. Outcomes from tests at model and prototype scale are described, and a simple mathematical model is presented. Predictions from the latter suggest that a ducted turbine can produce very high specific power outputs, going some way to offsetting its directional sensitivity. Further predictions using climate files are made to assess annual energy output and seasonal variations, with a conventional small wind turbine and a photovoltaic panel as comparators. It is concluded that ducted turbines have significant potential for retro-fitting to existing buildings, and have clear advantages where visual impact and safety are matters of concern

The development of a generic systems-level model for combustion-based domestic cogeneration

The provision of heat and power to dwellings from micro-cogeneration systems is gaining credence around the developed world as a possible means to reduce the significant carbon emissions associated with the domestic sector. However, achieving the optimum performance for these systems requires that building design practitioners are equipped with robust, integrated models, which will provide a realistic picture of the cogeneration performance in-situ. A long established and appropriate means to evaluate the energy performance of buildings and their energy systems is through the use of dynamic building simulation tools. However, until now, only a very limited number of micro-cogeneration device models have been available to the modelling community and generally these have not been appropriate for use within building simulation codes. This paper describes work undertaken within the International Energy Agency's Energy Conservation in Building and Community Systems Annex 42 to address this problem through the development of a generic, combustion based cogeneration device model that is suitable for integration within building simulation tools and can be used to simulate the variety of Internal Combustion Engine (ICE) and Stirling Engine (SE) cogeneration devices that are and will be available for integration into dwellings. The model is described in detail along with details of how it has been integrated into the ESP-r, Energy Plus and TRNSYS simulation platforms

Constructive Interpretation in Design Thinking

This thesis explores the role of interpretation in design activity through the development of a computational model of constructive interpretation. It asks the question: how does the construction of interpretations from expectations within a situation affect design activity? This work hypothesises that designers construct their world from their expectations through interpretation. In interpreting their own work designers are able to make unexpected discoveries and explore the implicit knowledge held within their expectations of the world. These expectations are grounded in experience. A conceptual model for constructive interpretation is described. Knowledge held by designers is represented in a perceptual symbol system, in which knowledge organised in a hierarchy. Within this hierarchy, higher layers represent an increased level of abstraction. Knowledge is learnt through experience in an environment. The topmost layer in this hierarchy is the situation.Interpretation occurs through pull from the expectations. Expectations in a layer are changed by the layer above. The construction of expectations utilises knowledge about the world that the designer gains through experience. A computational framework for this conceptual model is described: (i) based upon conceptual spaces, where expectations within the situation perturb each other; and (ii) based upon a hierarchy of unsupervised learning networks, where prototypes represent convergence zones within conceptual space. Constructive interpretation is implemented in a number of demonstrations utilising modified self-organising maps linked together to represent layers in the conceptual model. Demonstrations show: (i) how situations are changed through construction from implicit expectations; (ii) how situations co-ordinate concepts through expectations that are grounded in experience; (iii) how construction from expectations produces stability in a chang ing environment; and (iv) how useful rather than accurate in! terpreta tions can be produced by constructing from expectations. A model of constructive interpretation in design is developed in which a system iterates through generation of designs from expectations and constructive interpretation. In one experiment an agent has experience with a number of floor plans. It uses its experience to draw in a design medium and interpret its own work. Through constructive interpretation from implicit expectations the situation changes leading to a new space of designs. It provides a model of the way that designers make unexpected discoveries within their work that are useful to the design task, through expectations, and relevant to the source, as the basis for constructing the interpretation. Another experiment uses sets of growth indicators about countries as concepts. The model shows how the space of designs changes through constructive interpretation and explores the effects of salience weighting upon the construction of interpretations. The work looks towards a situated model of design: a model of design that integrates interpretation, expectation and memory into the one cognitive framework. Constructive interpretation has applications for models of analogy and computational creativity. Future work in constructive interpretation is described

Developing the repository manager community

This paper describes activities which have taken place within the UK institutional repository (IR) sector focusing on developing a community of practice through the sharing of experiences and best practice. This includes work done by the UK Council of Research Repositories (UKCoRR) and other bodies, together with informal activities, such as sharing the experience of organising Open Access Week events. The paper also considers future work to be undertaken by UKCoRR to continue developing the community

Modelling the impact of micro generation on the electrical distribution system

In the UK and elsewhere there is considerable debate as to the future form of the electricity distribution system. The coming years will see a rise in the amount of micro-generation connected to the network at low voltages and the emergence of highly-distributed power systems (HDPS). However, there is considerable uncertainty as to the impact that this micro-generation will have on the quality of power supplied to our homes or to the stability of the electricity system as a whole. To address these engineering challenges the UK Engineering and Physical Sciences Research Council (EPSRC) is funding a three year research programme featuring a multi-disciplinary team from a variety of UK Universities: Supergen HDPS. This paper documents one piece of work emerging from the consortium, where a multi-tool approach is used to analyse the impact of micro-generation on the electricity system. This used a building simulation tool to produce electrical generation profiles for domestic cogeneration device models. These, along with profiles produced for other micro-generation technology models and electrical load profiles are then replicated and aggregated using a customised statistical approach. The profiles were then used as boundary conditions for a set of electrical load flow simulations on a model of a section of real network, where the number of microgenerators was varied according to different scenarios for the future of the UK electricity grid. The results indicate that a significant number of micro-generation devices can be accommodated before any power quality problems arise, however this is dependent upon maintaining a robust central grid

An occupant-differentiated, higher-order Markov Chain method for prediction of domestic occupancy

Household energy demand is closely correlated with occupant and household types and their associated occupancy patterns. Existing occupancy model performance has been limited by a lack of occupant differentiation, poor occupancy duration estimation, and ignoring typical occupancy interactions between related individuals. A Markov-Chain based method for generating realistic occupancy profiles has been developed that aims to improve accuracy in each of these areas to provide a foundation for future energy demand modelling and to allow the occupancy-driven impact to be determined. Transition probability data has been compiled for multiple occupant, household, and day types from UK Time-Use Survey data to account for typical behavioural differences. A higher-order method incorporating ranges of occupancy state durations has been used to improve duration prediction. Typical occupant interactions have been captured by combining couples and parents as single entities and linking parent and child occupancy directly. Significant improvement in occupancy prediction is shown for the differentiated occupant and occupant interaction methods. The higher-order Markov method is shown to perform better than an equivalent higher-order ’event’-based approach. The benefit of the higher-order method compared to a first-order Markov model is less significant and would benefit from more comprehensive occupancy data for an objective comparison

NASA Cold Land Processes Experiment (CLPX 2002/03): ground-based and near-surface meteorological observations

A short-term meteorological database has been developed for the Cold Land Processes Experiment (CLPX). This database includes meteorological observations from stations designed and deployed exclusively for CLPXas well as observations available from other sources located in the small regional study area (SRSA) in north-central Colorado. The measured weather parameters include air temperature, relative humidity, wind speed and direction, barometric pressure, short- and long-wave radiation, leaf wetness, snow depth, snow water content, snow and surface temperatures, volumetric soil-moisture content, soil temperature, precipitation, water vapor flux, carbon dioxide flux, and soil heat flux. The CLPX weather stations include 10 main meteorological towers, 1 tower within each of the nine intensive study areas (ISA) and one near the local scale observation site (LSOS); and 36 simplified towers, with one tower at each of the four corners of each of the nine ISAs, which measured a reduced set of parameters. An eddy covariance system within the North Park mesocell study area (MSA) collected a variety of additional parameters beyond the 10 standard CLPX tower components. Additional meteorological observations come from a variety of existing networks maintained by the U.S. Forest Service, U.S. Geological Survey, Natural Resource Conservation Service, and the Institute of Arctic and Alpine Research. Temporal coverage varies from station to station, but it is most concentrated during the 2002/ 03 winter season. These data are useful in local meteorological energy balance research and for model development and testing. These data can be accessed through the National Snow and Ice Data Center Web site