This paper introduces a concept of robustness of an air distribution method, which is defined as being capable of meeting the ventilation requirements during varying operational conditions. The robustness performance may be particularly important when the system allows individual control of the supply air parameters. As a preliminary example, plenum-based (ductless) air distribution methods are studied using computational fluid dynamics.
The efficiency of an exhaust system is especially important in a kitchen environment in which the exhaust is located at ceiling level. The capture efficiency of the total system must be guaranteed so that the spread of impurities throughout the kitchen is prevented. A capture efficiency model is derived and it is used to estimate the efficiency of a ventilated ceiling.
This study examines the way of utilizing a ceiling fan for airflow control in a large air-conditionedroom. Although it seems that CFD simulation is useful in predicting the airflow around a ceiling fan, modeling of a ceiling fan as a body of rotation is very complicated. Therefore, in this study, airflow of a ceiling fan is modeled as boundary conditions of air velocity data measured near the ceiling fan.
The airflow conditions in an experimental pig housing unit are examined both experimentally and numerically (simulation) with particular focus on the airflow conditions in the occupational zone of the animals. Two heating setups are used, and the temperature is measured in a horizontal profile at the floor and at the ceiling. Good concordances between the measurements and the simulations are reached at the floor level. At the ceiling level, the conformity to the measuring results is unsatisfactory.
The capture efficiency of the total system must be guaranteed so that the spread of impurities throughout the kitchen is prevented. A capture efficiency model is derived and it is used to estimate the efficiency of a ventilated ceiling. This paper demonstrates that a simple equation that includes the average contaminant level in the occupied zone and the exhaust concentration could be a suitable platform for capture efficiency analysis in both measurements and simulations.
Research has shown that highly efficient solar powered ceiling fans improve thermal comfort and potentially provide health benefits when air conditioning or conventional ceiling fans are not available, such as during the 2003 summer heat waves in Europe, and in many undeveloped areas of the world. Ceiling fans can improve the spatial effectiveness of heating, ventilation and air conditioning (HVAC) systems. They can reduce air conditioning energy use if occupants increase thermostat set-points and reduce frequency of operation, and if waste heat from the fan motor is minimized.
The particle deposition on ceilings causing the soiling of induction outlets is mainly caused by the features of mixed ventilation.This paper offers a solution to the problem. The search for a clean outlet is made easier with the proposed optical and experimental technique that suggest to visualize the soiling patterns of an outlet by photographing deposited sodium chloride crystals. These tracer-particles stem from an atomizer and aerodynamically behave like the particles responsible for the soiling of ceilings in reality.
Velocity measurements were performed in the air flow resulting from two horizontal opposite air jets along a ceiling. Results show how the air velocity decreases along each of the two air jets, compared to the velocity decrease along a single free air jet.Experimental results are compared with a correlation from the literature. The agreement is good.
The ventilated ceiling is a flexible solution for kitchen ventilation where the heat loads arerelatively low and aesthetics is a concern. The use of hoods is an ideal solution for locallyhandling contaminants produced in concentrated areas. Thus, special attention should betaken on the ventilated ceiling which removes air at the ceiling level. The simulationsconducted show that the capture jet improves the total effectiveness of the ventilated ceiling.Indoor air quality is enhanced in an energy efficient manner.
The experimental investigation of airflow performance in a ceiling slot-ventilated enclosure under an isothermal condition was the aim of that study. Air-flow characteristics have been analyzed via experimental data then compared to literature theoretical expressions.
The results will be used in design guidelines of ventilation system for controlling indoor environment.