Tracer gas measurements have Jong been used to quantify the performance of ventilation systems by exploring such scales as the air exchange efficiency, the local mean age of the air, the residence time distribution and so on. The present work deals with a numerical reexamination and calibration of some relations previously derived from tracer gas analysis.
The purpose of this paper is to evaluate the performance of four kinds of ventilation systems from the point of view of air exchange, indoor air pollution, and space heating load under Japanese conditions by numerical simulation. TVOC and CO2 are selected to characterise the indoor air quality impact to residents. The results show that the equivalent leakage area has great influence on air movement.
The study of the flow in a room cooled by a fan-coil pointed out how the form of air flow and comfort could be influenced by the characteristics of the cold jet blowing out. It is based both on practical experiment and on numerical simulation using CFD code. Combining these methods allowed a large number of configurations to be studied, in association with different conditions for the appliance. Using the results in combination enabled a relation to be established between the problem data, the device characteristics and the comfort conditions obtained.
This paper describes the development of software for simulating the air-conditioning environment in a computer room. This software uses a finite volume method combined with a rectangular structured mesh system and a k-£ two-equation model for turbulence. Some special modeling techniques are also used. This software has two purposes: (1) to optimize the layout of a computer room, thus minimizing the electric power used for air conditioning, and (2) to reproduce the situation in which an accident is caused by an air-conditioning problem and to assist in an investigation of the problem.
This paper considers the numerical modeling of room airflows and illustrates the usefulness of computational fluid dynamics as a design tool for ventilation systems. A computer code, which simulates steady, buoyant, turbulent, three-dimensional flows in Cartesian coordinates, was developed. The time-averaged equations for conservation of mass, momentum, and energy are solved. A low Reynolds number kE model is used to simulate the turbulent transport. The code was validated by comparing it to benchmark data for both liddriven and buoyancy-driven cavity flows.
The rising stream around a human body attributable to metabolic heat can carry contaminants from the floor level to the human breathing system. Thus, the quality of the breathing air greatly depends on the concentration distribution in the lower part of the room and the characteristics of the local air motion around the body. In this paper, a modeled human body (computational thermal manikin) is placed in a room that is air-conditioned with a displacement ventilation system.
A three-dimensional computational fluid dynamics (CFD) analysis has been used to predict airflow patterns in laboratory fume hoods. The simulation includes bypass fume hood primary operational features including the top and bottom bypasses, front airfoils, and rear-slotted baffles. All results were validated experimentally, and the simulation was found to adequately predict fume hood airflow patterns. The results indicate that fume hood flow patterns are highly dependent on inlet flow boundary conditions so that the computation must include the near field room airflow.
The present research applies the N3S 3D finite element CFD code to the air flow simulation on a well-known dwelling building located in South of Switzerland, the " Maison Ronde " of the architect Mario Botta. The summer night refreshing effect is examined when crossing ventilation due to the wind creates indoor air motion and for cooling walls and ceilings surfaces. To be realistic, the simulation takes simultaneously into account the three main aspects of the problem: - determining boundaries conditions.
The purpose of this paper is to evaluate the performance of 4 kinds of ventilation systems from the point of view of indoor air pollution and energy need during heating season under Japanese conditions by numerical simulation. TVOC was selected to characterize the indoor air quality impact to residents. The results show that in the case of mechanical exhaust ventilation system, TVOC level is the highest among all the systems. Mechanical central supply and exhaust ventilaton system shows its advantages for minimizing energy consumption and maintaining an acceptable indoor air quality.
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