English

An irregular grids finite volume procedure is presented for flows in complex geometries. The technique carried out computation in the physical plane itself, without any coordinate transformation. Equations are written in Cartesian velocity components and are discrete in physical domain using a cell-centred, staggered grid finite volume method. It is shown that the present formulation ensures that computational scheme is diagonally dominant.

In air conditioning system, air blowing patterns have very important influence on the comfortable state and the energy consumption of air conditioning environment. When pulse-blowing pattern is adopted, different density particle can gain different acceleration due to the change of airflow acceleration in pulse blowing. For the particle with higher temperature and larger humidity, its density is smaller and its acceleration is smaller in pulse blowing.

Measurement data and analysis of air distribution in one gymnasium is presented in which the airflow is isothermal. The region considered includes both workaround and non-workaround, which can describe the airflow pattern of this gymnasium correctly. Based on measured data, the airflow pattern of the HVAC system is analysed. And the characteristic of airflow pattern in this kind of large space is summed up. Then some conclusions are drawn as a guide for airflow pattern designing in large space of the similar type.

The increased sensibility, as far as the environmental demands are concerned, has intensified the research which aims at minimizing the energy consumption in buildings as well. In order to accomplish this task, new concepts and developments are necessary. Among those, the Second Skin Facades can play an important role. A simulation using the simulation code Simulink was set up.

This paper derives some new analytical solutions for buoyancy-driven natural ventilation in buildings with three openings. The new solutions are used to analyse the effect of the middle opening height and area on the natural ventilation performance. The criteria for flow direction switching for the middle opening is established. It is also proved that the neutral plane level in the three-opening buildings depends only on geometrical parameters. Natural ventilation of buildings with two openings affecting by supply- or exhaust-only mechanical systems are also investigated analytically.

The instantaneous temperatures close to a diffuser for displacement ventilation have been measured by using a whole-field measuring method. The air temperature was measured indirectly by using infrared thermography with a digital infrared camera and a measuring screen. By moving the measuring screen the whole field around the diffuser was measured. A method has been developed for combining the tow-dimensional measurements to produce a three dimensional representation.

This study investigates the impacts of the three different types of carpark namely open (on surface), multistory and integrated carpark. The 1:200 scaled models were used in wind tunnel to gather pressure distribution data on the exterior surface of surrounding housing blocks. The data were collected from testing the various wind directions on different types of carpark. Using pressure coefficient (Cp) values, the ventilation performances represented by air change rate (ACH) in the selected units were calculated using CONTAM.

Indoor air contaminants may be grouped into four categories: microbial contaminants; respirable particles; gaseous contaminants, and vaporous contaminants. Conventional filters like HEPA filters can only be useful for bioaerosols and respirable particulate. Absorbers such as activated adsorbed can be useful for almost all gases and vaporous contaminant, but eventually they will lose efficiency. Photocatalysis can remove all VOCs and bioeffluent, but not very useful for gases contaminant such as ammonia.

This paper presents the feasibility of predicting the transient CO2 levels in a classroom. Air measurements in the classrooms were taken to determine the fresh air change rate and ventilation effectiveness by means of tracer gas method. The fresh air change rate, effectiveness, occupancy, and outdoor CO2 levels were used as inputs for prediction of indoor CO2 concentration. The general profiles of predicted CO2 concentrations are quite similar to that of the measured values. The ventilation rate is often overestimated.

One of the reasons for using displacement ventilation is that it may provide better indoor air quality in the occupied zone than conventional mixing ventilation. It is therefore important to understand the importance of the system on this aspect. A validated CFD model was employed to generate concentration distribution data for CO2, radon and moisture in a Hong Kong shop with displacement ventilation. Analysis found that the concentration distribution affected by factors such as the source type and location, its associated plume strength and human body convection, etc.