English

An energy and cost analysis has been performed which compared a dedicated outdoor air system (DOAS) with chilled radiant cooling panel (CRCP), designed for an official building located in the hot and humid climate of Chennai, India, and an existing VAV system with total energy recovery (TER). In addition to the benefits of providing the right quantity of ventilation all the time to maintain IAQ at the better level, as prescribed by ASHRAE Standard 62, an annual energy savings of 20 percent was predicted when compared with the VAV system with total energy recovery.

Natural ventilation associated with shading techniques is an alternative way to reduce the use of expensive and environmentally harmful active systems, while providing summer thermal comfort and good indoor air quality. However, there is still a lack of knowledge concerning the design of such systems. The tool presented in this paper provides guidelines on natural ventilation and shading control strategies. This tool (called PHACES) has been developed under the MATLAB/SIMULINK environment by modelling an experimental device (HYBCELL) designed at the LASH/ENTPE laboratory.

This paper deals with tomographic techniques for two-dimensional spatially resolved concentrationmeasurements indoors. This represents a significant advance over the traditional point measuring method for mapping tracer gas and pollutants. Methods for recording of data are stressed as well as different types of tomographic reconstruction algorithms such as the Smooth Basis Function Minimization (SBFM) and the modified Low Third Derivative (LTDm) methods. Among the reconstruction algorithms available today, SBFM and LTDm are among the most promising.

A formulation to analyze ventilation duct system airflows employing, as the basic unknowns, the flow rates in the channel sections and the static pressures at the channel section ends is presented. This approach is called the PQ-formulation and the corresponding system equations are called PQ-equations. The system equations in the PQ-formulation are the engineering Bernoulli equations for the channel sections, the inlet and outlet pressure jump equations at the inlet and outlet nodes, the continuity equations at the junctions and the pressure jump equations at the junctions.

A methodology approach to simulate, by means of computational fluid dynamics (CFD) tools, a greenhouse equipped with a fan and pad evaporative cooling system is presented. Using the main aspects of evaporative cooling systems, in terms of heat and mass transfer, the flow and boundary conditions of the simulation model are identified taking into account both the external and internal climatic conditions. The crop (tomato) was simulated using the equivalent porous medium approach by the addition of a momentum source term.

The basis for room air distribution solutions in ventilating and air conditioning rooms is the calculation of velocities in air jets from supply outlets. To calculate velocities, the C-value of the air outlets must be known. The aim of this contribution is to acquaint readers with a non-traditional method for defining the C-value of an outlet from the angle of air jet expansion in the main jet zone, determined using interferometric visualization of the jet.

In this study, the measured and predicted air distribution of an active chilled beam in a typical office room is described. A free convection model was applied for the vertical downward air jet along the wall by superposing a free convection velocity and an isothermal jet velocity. The velocity and temperature of the wall jet were measured at six different heights and six distances from the wall in the near wall zone and in the wall-floor corner zone. The experiment implemented two airflow rates of 20 and 28 L/s with three cooling loads of 0, 40 and 100 W/m2.

The important error sources associated with measurements using low velocity thermal anemometersincorporating an omnidirectional velocity sensor (LVTA) are identified and quantified. The impact of natural convection, directional sensitivity and dynamic response of the anemometer are modelled. The developed models, together with a database of instantaneous velocity records obtained by means of a Laser Doppler Anemometer are used to estimate the uncertainty of mean velocity and standard deviation of velocity measurements by LVTA.

A study was performed on the effects of porosity on discharge coefficient and airflow characteristics under the condition where uniform approaching flow directly faces to and enters the opening by using wind tunnel experiment and CFD analysis. The evaluation was performed on porosities in the range 0.4% - 64%. The results of wind tunnel experiments suggest that the discharge coefficient increases when the porosity is higher.

The purpose of this paper is to provide a multicriteria approach in order to develop and assess several control methods for hybrid ventilation. This is important because there is currently a great interest in hybrid ventilation as an energy efficient strategy for achieving thermal comfort and good indoor air quality. To reach those targets and manage hybrid ventilation systems, advanced control strategies, based on hierarchical fuzzy controllers, have been developed at the LASH laboratory.