English

A mathematical formulation was developed including an objective function that minimizes the cumulative exposure of occupants to pollutants under the constraints of pollutant dispersion pattern, evacuation paths, and their capacities. The formulation included airflow and pollutant dispersion models and optimization algorithms for evacuation planning. The formulation was applied to two example cases. Assuming that a simulated pollutant (SF6) was released at the HVAC intake or inside a particular zone of the building, simulations were conducted for

This paper compares two models that were developed independently for predicting the particle separation efficiency of a vane-induced uniflow cyclone. The Zhang model was based on indirect analysis. Both models were further derived to show that the particle separation efficiency depended on reynolds number and particle property. Experimental data from a uniflow cyclone were collected to compare with the two models. Particle separation efficiencies of the uniflow cyclone were measured at three reynolds numbers. The predictions using the Zhang model were closer to the experimental data.

Relative humidity sensors are common components in building heating, ventilating and air-conditioning (HVAC) systems, and their performance can significantly impact energy use in these systems. Therefore, a study was undertaken to test and evaluate the most commonly used relative humidity sensors in HVAC systems, namely, the capacitive and resistive types. The procedures presented here provide a methodology to test and evaluate duct-mounted relative humidity sensors for accuracy, linearity, hysteresis, and repeatability.

In a local exhaust ventilation system, the exhaust air velocity decreases very rapidly with distance from the exhaust inlet.One possible way of maintaining a high capture velocity far from the exhaust inlet is the use of vortex flow, usually called a "vortex ventilation system", which has a rotating annular disk installed in the exhaust inlet.

Local airflow gives different sensations at different locations on a human body as the thickness of natural convection is not equal over the body surface. This study is intended to examine the effect of horizontal local airflows with different temperatures and velocities on thermal sensation, airflow perception, and thermal comfort to develop economical air conditioning especially for hot and humid areas. The subjects'votes concerning the back of the neck and the ankles in summers and winters were examined statistically.

The laboratory air-handling unit (LAHU) system is designed to improve building energy performance and indoor air quality (IAQ) in laboratory buildings. The LAHU system sends more (up to 100%) outside air to the office section and recirculates the office section air to the laboratory section.

The objective of this investigation was to evaluate the field performance of room air distribution in two rooms of a high performance home (low heating and cooling load). The two rooms had similar exterior exposures but had different supply register locations (high sidewall and floor). The impact of normal equipment cycling on the room air distribution perfomance was also investigated. The performance was evaluated based on room air temperature measurements and the requirements of Ashrae standard 55.

This paper present a survey technique for rating HVAC systems. System components are grouped into categories. The components inside the categories are numerically rated from 1.0 to 5.0 in terms of mechanical system maintenance, service performance, and operation efficiency of the mechanical equipment. The component scores are averaged for each category. These scores are then averaged to give a single score for the whole system. A trial was conducted : ten independent assessors with different years of job experience examined a range of equipment from two major HVAC systems (N = 200).

This study aims at developing a radiant floor cooling system using the existing Ondol (radiant floor heating system). It was found that the proposed system could provide cooling for thermal comfort with higher energy efficiency. However, problems still exist due to the condensation on the floor surface while the radiant floor cooling system is in operation.

This paper proposes an intelligent controller for an air-handling unit to control the temperature while limiting the humidity below 70%. The proposed scheme is based on the back-propagation-through-time approach. It uses artificial neural networks to develop an emulator to learn on-line the plant dynamics and a controller to control the fan speed and chilled water valve opening in real time. The neural-based controller was implemented on an industrial air handler for performance validation purposes.