Evaluation of COMIS - Appendices.

Evaluation of COMIS.

A type of dynamic calculation of indoor temperature distributions.

The requirements to know indoor thermal comfort ask for a more detailed study of room temperature responses. Although CFO (Computational Fluid Dynamics) techniques can be applied successfully to the prediction of indoor temperature distributions, using them for the dynamic calculation of temperatures and air flows is still a very expensive expenditure. For indoor climate control systems, it is necessary to make quick calculations of the dynamic temperature distributions in a room.

A state space model of indoor temperature distributions.

To control the indoor thermal environment within the comfortable range, the dynamic temperature distributions and flows of room air must be correctly predicted. While the CFO (Computational Fluid Dynamics) technique can be used to carry out such a prediction task, its drawback is also obvious: too time-consuming. To solve this problem, the dynamic temperature distributions can be predicted with some fixed air flow fields calculated with CFD codes. That is, sacrifice the dynamics of indoor air flows and only preserve the dynamics of the temperature distributions.

Modelling of the indoor environment - particle dispersion and deposition.

A three-dimensional drift-flux model for particle movements in turbulent airflows in buildings is presented. The interaction between the carrier air and the particles has been treated as a one-way coupling, assuming the effect of particles on air turbulence is negligible due to low solid loadings and comparatively small particle settling velocities. Turbulence effects are modelled with a standard K-E model. Wall functions are applied at near-wall grid points. Aerosol measurements carried out under turbulent room flow conditions are used to validate the numerical calculations.

Deflection of wall-jets in ventilated enclosures described by pressure distribution.

The pressure field in fluid systems reflects the flow configuration. Measurements of the pressure along the perimeter of a slot ventilated room have been conducted for different room sizes. The momentum of the jet at the end of the room is decreased with increasing room length. The impingement region (region where the influence of the opposing wall is present) starts, independent of room size, when the distance from the supply device is about 70% of the room length. Corner flows could not be predicted by CFD using the linear eddy viscosity or standard stress models. However.

Modelling the thermal distribution efficiency of ducts: comparisons to measured results.

This paper presents a comparison of predictions from a duct efficiency model developed by the authors with measured real-time heating n, system efficiency measurements from six site-built residential homes with natural gas furnaces in the Puget Sound region. The model takes into account the interaction between supply and return side losses, the interaction between conduction and air leakage losses, the interaction rs between unbalanced leakage and natural infiltration, and the recovery of heat through the building envelope from ducts in various locations 1) within the home.

A zero-equation turbulence model for indoor airflow simulation.

At present, Computational-Fluid-Dynamics (CFO) with the 'standard' k-e model is a popular method for numerical simulation of room airflow. The k-e model needs a lot of computing time and large a computer. This paper proposes a new zero-equation model to simulate three dimensional distributions of air velocity, temperature, and contaminant concentrations in rooms. The method assumes turbulent viscosity to be a function of length-scale and local mean velocity.

Calculation of convective heat transfer coefficients of room surfaces for natural convection.

Convective heat transfer from internal room surfaces has major effect on the thermal comfort, air movement and heating and cooling loads for the room. Recent studies have shown that the values of convective heat transfer coefficient used in building thermal models greatly influence the prediction of the them1al environment and energy consumption in buildings. In computational fluid dynamics ( CFD) codes for room air movement prediction accurate boundary conditions are also necessary for a reliable prediction of the air flow.

A continuous time dynamic model of temperature in air conditioned rooms.

The numerical evaluation of room air movement is made by systematic discretization of space and the dependent variables. This makes possible to replace the governing differential equations with simple algebraic equation. The dynamic model of the temperature is based on the energy balance equation, considering a given flow field. The temperature in a given control volume depends on the temperatures of its corresponding neighbours. This form of the model is. not appropriate for control theory.