Assessment of Heat and Mass Transfers in Building Porous Materials

Heat and mass transfers in building materials influence the thermal properties and performances ofthe materials more especially as they are porous. This paper deals with the case of various porousbuilding materials (Aerated Autoclaved Concrete, Hemp Concrete and Vertically Perforated Brick)studied by an experimental approach. A cell of exchange makes it possible to impose on a sample,gradients of temperature and relative humidity variables as function of time. The performances ofthese materials are thus deduced from the evolution of T and %RH in several positions.

Feasibility of CFD Simulation Applied to Air-Conditioning Systems of Telecommunication Rooms

The purpose of the present study was to evaluate the possibility to reproduce heat and air flowcharacteristics in a machine room where high heat generating systems and devices are installed. For this purpose, in an experiment room was air-conditioned by double floor air supply on the assumption that the machine room, data were selected such as air flow rate of the systems and various boundary conditions were elected. Further, double floor supply air flow rate distribution, and heat and air flow distribution in the room were measured.

Optimal supply air temperature with respect to energy use in a variable air volume system

In a VAV system, it is possible to minimize the energy use with an optimal supply air temperature. The theory for such a device is presented. The analyses show that controlling the supply air temperature in an optimal way results in a decrease of HVAC energy use compared with a constant supply air temperature.

Experimental Comparison of Thermal Environment between Ceiling-based and Floor-based System with CAV HVAC System

The present paper evaluates indoor thermal environment, cooling efficiency and energy consumption between a floor-based system and a ceiling-based system using a mock-up model in cooling period. The experimental chamber has a UFAC, underfloor air conditioning system and a ceiling-based system. And the experiments are set with practical internal load conditions including occupants, lighting units, and heat sources (office automation equipment). The following were compared and evaluated;
1) the vertical and horizontal temperature distribution,

Parametric Study on a Displacement Ventilation System Using Three-Dimensional CFD

This paper examines airflow in rooms for a displacement ventilation system using threedimensionalCFD. A parametric study is executed for a typical office room with a dimension of 6m by 6m by 3m height according to a variety of supply air velocities, supply air temperatures and heat sourceconditions. A finite volume method and standard k- e turbulence model is employed to solve the governing equations. As a result, the temperature field in the modeled room for a displacement ventilation system is concluded according to a variety of the above parameters.

Performance of a passive cooling system

The performance of a passive cooling system was evaluated as part of design works for theproject of an auditorium. The passive cooling system incorporates an array of buried pipes together with a solar chimney. The natural ventilation is enhanced with the help of the solar chimney and fresh air is cooled by circulation within the buried pipes. The application of this system to the acclimatization of an auditorium was evaluated. A model was developed on this purpose, which allows foreseeing the temperature and relative humidity of the air in the auditorium.

Evaluation of Thermal Comfort of Inhomogeneous Thermal Environment Created by Task-Ambient Air Conditioning System Using Floor Air Outlet

Subjective experiments were carried out to evaluate thermal comfort of inhomogeneous thermalenvironment created in task area using floor air outlet. Subjects are allowed to control freely the air volume supplied from the floor air outlet and the angle of elevation of the central axis of the air jet discharged from the floor air outlet to get their thermal comfort.

Dynamic spatial three-dimensional thermal comfort analysis underneath a cyclist helmet

Nevertheless the proven benefit of a cyclist helmet in preventing serious head injuries whena crash occurs, many cyclist still refuse to wear a crash helmet. The main reason for not wearing acyclist helmet is the sensation of discomfort encountered when wearing one. This paper evaluates and analyses - for the first time - both local and global temperature levels and moisture production in order to obtain insight in the interaction between both mechanism, as a response to differences in effort level, air velocity and air temperature, and how to improve its thermal comfort features.

A Method of Designing Thermal Comfort Conditions in the Room with UFAD System

The paper presents a method of designing thermal comfort conditions in a room with an UnderFloor Air Distribution system (UFAD). A two-phase algorithm is based on: a steady or unsteady heat and mass transfer theory in the first step of computation and thermal comfort calculation in the second step. This method is implemented as the computer program UFAD_NET.