Air distribution in a room and design considerations of mixing ventilation by flow elements.

The paper shows detailed measurement of the air distribution in a room ventilated by mixing ventilation according to the specifications given by the International Energy Agency work. (Energy Conservation in Buildings and Community Systems programme, Annex 20). It describes a number of flow elements and how they are used as design tools. The flow elements are the throw of an isothermal jet and the change in jet velocity when the jet moves from the upper to the lower part of the room. A third flow element is the penetration length of a non-isothermal wall jet.

Performance of thermal distribution systems in large commercial buildings.

A field study was carried out to establish the performance of five thermal distribution systems in four large commercial buildings. They were standard single-duct or dual-duct constant air volume (CAV) system and variable air volume (VAV) systems, serving buildings with floor area greater the 2000 m2. Reports the duct air leakage. The ELAs ranged from 0.7 to 12.9 cm2/m3 of duct surface area, and from 0.1 to 7.7 cm2/m2 of floor area.

Airflow measurements for balancing of air distribution system - tracer gas technique as an alternative?

States that there are problems involved with the use of traditional instruments such as vane anemometers and pitot tubes when measuring airflow rates in HVAC systems in order to balance air distribution. Suggests that the simple and useful tracer gas techniques that are commonly used for ventilation measurements in buildings can be a suitable alternative. Describes a preliminary study intended to determine the viability and accuracy of the tracer gas technique. A good correlation between the airflow rates measured by using a pitot tube and tracer technique was found.

Use of computational fluid dynamics to aid studies of room air distribution: a review of some recent work.

Computational fluid dynamics has a wide range of application in the study of room air distribution. The application is providing valuable guidance for those interested in such areas as comfort, productivity and sick building syndrome. This paper gives a comparative review of some of the work undertaken in the field and highlights some of the modelling assumptions noted within the literature.

The effect of heat source elevation on ventilation effectiveness.

This study is a part of a research project called 'Convective Flows and Vertical Temperature Gradient within Active Displacement Air Distribution'. The project and the two zone model developed have been introduced by Sandberg (1). The aim of this study was to examine the ventilation effectiveness with different elevations and horizontal positions of the heat sources within active displacement air distribution. This was studied by carrying out experiments using convective heaters and ordinary fluorescent tube lamps at several elevations as heat sources.

Modelling of air distribution methods for zoning strategy.

Zonal models are often used in analytical calculation of temperature, concentration or humidity conditions in ventilated spaces. The space is divided in two or several zones ( 1 ). The zoning of the space is based on the assumption of constant temperature,  concentration and humidity in each separate zone. The balances for air mass flow, contaminant mass flow, water vapour mass flow and heat flow are determined between zones and between zone and outer boundaries.

A strategic approach for the room air conditioning design.

This paper discusses the application of a new strategy approach for the room air conditioning. The basis of the classification is different aims or ideas of the temperature, gas, particle, humidity distributions and room air flow patterns that can be created within a room. A certain strategy can be applied by using different system combinations of room air distribution, exhaust, heating and cooling methods and their control. The realization of an ideal strategy is also dependent on the operating parameters and internal sources.

Characteristics of buoyant flow from open windows in naturally ventilated rooms.

An important element in the natural ventilation design procedure is the flow-pressure characteristics of a window with a given opening area. The flow in the room is another important element that is often ignored in the design phase due to lack of relevant information on the air movement. This paper shows the outcome of experiments with the room air distribution. The results show that the velocity distribution in the occupied zone can be described by a semi empirical model.

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