Environmental design using dynamic insulation.

In conventional airtight buildings, the architect has considerable freedom to decide how much the external environment will influence the internal heating, cooling, and ventilation loads. The services engineer provides the plant and equipment required to deal with these loads. This division of labor could lead to undesirable consequences in the case of dynamic insulation, a form of air permeable construction where bulk air flow through the building envelope may be used to either enhance or restrict the conductive heat and mass diffusion fluxes. Small changes in temperature (indoor and out) and wind speed and direction will influence the behavior of a dynamically insulated envelope since the internal and external environments are much more intimately coupled. Buildings employing dynamic insulation thus require good environmental design principles to be applied. The objective of this paper is to lay down rigorous principles that will form the basis of guidelines to architects and building services engineers on how to take account of the ever changing external environment when designing durable and comfortable buildings employing dynamic insulation

Dynamic insulation in multistorey buildings.

Dynamic insulation permits the movement of air and moisture through the external walls of a building to reduce heat loss and achieve high indoor air quality. The present paper details a pilot study carried out to examine the influence of fire safety requirements and external wind on the performance of naturally ventilated multistorey buildings in which the external envelope is dynamically insulated. The theoretical foundation is outlined for a spreadsheet model used to simulate prototype 3-, 4-, 5- and 10-storey buildings all sharing the same rectangular floor plan, with fresh air drawn into the building through the envelope by depressurisation using a fan-driven, ducted extract system. From the analysis, the effects of wall porosity, depressurisation level, extract system deployment, occupant density and distribution, and building orientation have been quantified, confirming the practical feasibility of such a system

The use of dynamic and diffusive insulation for combined heat recovery and ventilation in buildings.

Modern buildings, domestic and commercial, have attempted to reduce their energy requirements by improving the airtightness of the envelope and increasing the thickness of insulation. However, this trend has developed simultaneously with increased use of synthetic materials in construction, furnishings and decorations, which give off volatile organic compounds, and increasing living standards which result in higher indoor temperature and moisture generation rates within homes. The result has been a reduction in indoor air quality which directly affects occupant health and increasing problems of dampness in homes, particularly for the poor

Pilot scale production of novel calcium sulfoaluminate cement clinkers and development of thermal model

Pilot scale trials were successfully performed on the production of novel calcium sulfoaluminate (CSA) cement clinker in a direct natural gas heated rotary kiln at the IBU-tec facility in Germany. A raw meal throughput of ∼25 kg/h was fed to the rotary kiln heated by co-combustion of natural gas and elemental sulfur, with the latter serving as both fuel substitute and reactant, to partially or wholly replace gypsum as the source of sulfur in CSA production. A well-mixed heat transfer kiln model was developed to predict the overall kiln heat flux and gas temperature profiles, to account for gaseous radiative properties. The predicted gas temperature inside the kiln varied from 1566 K in the flame zone to 1019 K at the feed zone, with peak temperature approaching 1724 K. The combined emissivity of the CO2 and H2O gas mixture varied between 0.13 and 0.2 at these temperatures for partial pressure ratio PH2O/PCO2 of 1.7. The trial kiln has a low thermal efficiency of 3% of the total supplied energy. The simplistic model provided approximate performance predictions for the KDO kiln and also for different kiln sizes and can help to establish the effects of operating parameters on heat transfer trends

Dynamic insulation in multistorey buildings

Dynamic insulation permits the movement of air and moisture through the external walls of a building to reduce heat loss and achieve high indoor air quality. The present paper details a pilot study carried out to examine the influence of fire safety requirements and external wind on the performance of naturally ventilated multistorey buildings in which the external envelope is dynamically insulated. The theoretical foundation is outlined for a spreadsheet model used to simulate prototype 3-, 4-, 5- and 10-storey buildings all sharing the same rectangular floor plan, with fresh air drawn into the building through the envelope by depressurisation using a fan-driven, ducted extract system. From the analysis, the effects of wall porosity, depressurisation level, extract system deployment, occupant density and distribution, and building orientation have been quantified, confirming the practical feasibility of such a system

Stability of ternesite and the production at scale of ternesite-based clinkers

A method to synthesize high-purity ternesite is presented and the importance of reaction volume is highlighted; a brief description of the product morphology is also presented. Thermodynamic data for ternesite are derived and the limits of ternesite stability are then explored. An upper temperature stability limit of ≈ 1290 °C at 1 atm is determined; however, this temperature is dependent on the fugacity of the volatile components in the atmosphere. Thermodynamic predictions confirm that belite and ternesite rich calcium sulfoaluminate clinkers can be readily produced in a single stage process at temperatures above 1200 °C provided the atmosphere and temperature are controlled. To demonstrate this control at larger scales, a conventional 7.4-meter rotary kiln has been used to produce ≈ 20 kg of ternesite-containing clinkers. This demonstrates the usefulness of thermodynamic modelling as it has enabled ternesite-based clinkers to be readily produced at scale in a single-stage process using existing equipment without major modifications

Production of belite calcium sulfoaluminate cement using sulfur as a fuel and as a source of clinker sulfur trioxide: pilot kiln trial

A pilot-scale trial was undertaken in a 7·4 m kiln to demonstrate the production of belite calcium sulfoaluminate cement clinker using sulfur as a raw feed. The sulfur was introduced in its elemental form as fuel to the burner, thus partially offsetting fuel costs while providing sulfur trioxide which is incorporated in the clinker. The study demonstrates that sulfur trioxide is readily sequestered into cement clinker in a standard rotary kiln; however, some scrubbing of the exit gas may still be required. As the products of scrubbing (anhydrite or gypsum) are usually required to optimise the cement formulation, the recovered sulfur product can find an immediate use in the final cement product. This trial demonstrates the successful production of targeted belite calcium sulfoaluminate clinkers at scale using sulfur as both a fuel and sulfur trioxide source