Detailed Calculation Model Research Articles

Neutronics analysis of full MOX BWR core simulation experiments – FUBILA: Part 2

A part of the experimental program FUBILA was dedicated to the study of core physics characteristics of full MOX BWR cores by testing five experimental cores: a core inserted with a B4C control blade, a core loaded with UO2 fuel rods, the core loaded with Gd2O3-UO2 fuel rods, a core loaded with 10 × 10 MOX assemblies and a core loaded with time-elapsed MOX fuel. The present article describes analysis results of the experimental data with deterministic analysis codes and a continuous energy Monte Carlo code coupled with major nuclear data libraries. The calculated critical k eff's with the Monte Carlo calculations range from 0.999 to 1.007. Those of the transport calculations with sixteen energy groups are close to those of the Monte Carlo calculations while those of diffusion calculations with the same sixteen energy groups are systematically smaller by −0.3 to −0.5% Δk than those of the Monte Carlo calculations. The RMSs of differences between the calculated and measured core radial fission rates are 2 to 3%, 1 to 2%, and 1 to 2% for the diffusion, transport and Monte Carlo calculations, respectively. For the analysis of the Gd2O3-UO2 fuel rod loaded core, the C/Es of the radial fission rates were improved by adopting a detailed lattice calculation model and a newly measured thermal and resonance cross-sections of Gadolinium.

Distribution of Emerged Energy for Daylight Illuminate on Prismatic Elements

Prismatic elements are typical devices of natural light illumination system for redirecting and collecting daylight. Based on the principles of optics, this paper presents a simple mathematical matrix ray-tracing methodology through which a detailed intensity distribution of parallel light beam incident onto a right angled prism from different incident angles can be calculated precisely. We also present the distribution of the secondary emerged intensity from a prism illuminated by the emerged light of an adjacent prism. The direction, concentration, and distribution of intensity of the emerged light from the parallel light incident onto a surface of the right-angle prism, as well as daylight illuminate on a prismatic collector, are precisely calculated. The detailed calculation of the emerged light re-incident onto the adjacent prism or emerged out of the prismatic element presented that most of daylight are directly emerged out and are confined in some directions at earlier morning and afternoon, and the emerged light re-incident into the adjacent prism at noon around. This detailed calculation model of parallel light beam incident to a prismatic element can be applied to the hybrid natural light illumination system, as well as to the prism-relative solar illumination system for the improvement of efficiency.

Dependence of modelled evacuation times on key parameters and interactions

Times and patterns of buildings evacuations involve interactions between many behavioral parameters reflected in the increasing complexity of computer simulations. A combination of detailed GridFlow computer evacuations simulations, calculation models and experimental evacuations have been used to determine the extent to which evacuation patterns and times are largely dependent upon a small number of key parameters and interactions. Cases investigated included a single retail enclosure and multi-enclosure, multi-storey office buildings designed following UK prescriptive guidance. It is concluded that evacuation times are very dependent upon a small number of critical factors (including pre travel activity time [PTAT] distributions, exit choice ratios, maximum flow rates, merge ratios, and densities of stationary and moving groups). Even sophisticated computer simulations can give misleading results if these factors are not adequately represented.. while simple calculation methods can provide a useful first estimate of evacuation times for designers, and a useful check on the performance of more complex simulation models.

Optical models of complex fenestration systems

The need for energy conservation in buildings has spurred innovations in window technologies. These products include windows combined with shading devices, and windows featuring complex glazing such as switchable glazing, diffuse glazing, translucent and transparent insulation, patterned or decorative glass, etc. Current fenestration simulation tools for energy performance product ratings do not cover complex fenestration products. This paper addresses the development of detailed calculation models to compute the optical characteristics of complex fenestration products made up of a mixture of clear and scattering glazing layers. The models take into account not only the optical properties of the individual glazing layers making up the window product, but also the haze and gloss properties of the glazing layers. Specific optical models are developed to compute the optics of a clear substrate with applied or laminated scattering film, and composite film made up of a number of homogeneous materials with known optical properties. A general optical model was also developed for screen-like glazing panes such as insect/shading screens, roller blinds, drapery sheets, honeycomb transparent insulation and fibreglass translucent glazing.

Technical and economical model for the freezing cost comparison of immersion, cryomechanical and air blast freezing processes

This paper presents a detailed calculation model able to evaluate and compare the technical and economic aspects of different freezing techniques (immersion, air blast and cryomechanical freezing). This model relies on both established thermodynamic rules and also on an expert study of the specific technical parameters of the freezing techniques with respect to the product behaviour. It provides a detailed stage-by-stage overview of the effective costs: investment costs, operational costs (human resource costs) and specific costs of each process (such as brine regeneration and cryogen loss). The results are in good agreement with existing data, and complete them.

Solar radiation transport through slat-type blinds: A new model and its application for thermal simulation of buildings

Although external and internal slat-type blinds (such as venetian blinds) are used frequently to reduce the solar load on windows, there are no detailed calculation models for such shading devices within detailed thermal simulation models (DSMs). A new calculation model (GLSIM-BLIND) has been written to either simulate blind systems accurately at each simulation time-step, or to simulate blinds approximately using simplified daily effective shading factors for each radiation component. In addition, the program calculates annual or monthly effective total solar transmittance values, or effective shading factors, which can be used in thermal calculations or in simple dynamic programs. The model can be used for a wide range of different blind systems and blind control strategies. It is suitable for optimising blind arrangements during the design phase of a building. This article shows the theoretical basis of the new calculation technique and demonstrates its application in thermal building simulations.