air conditioning

In this paper, characteristics of the indoor environment utilizing hybrid ventilation system andtask-ambient air-conditioning system are investigated every hour in a year in various types of office spaces by means of dynamic cooling and heating load analysis and CFD (Computational Fluid Dynamics) simulation.Authors had investigated the characteristics of the indoor environment of a hybrid ventilation system, utilizing natural and mechanical ventilation, with CFD simulation under various conditions of incoming outdoor air [1].

Subjective experiments with a non-isothermal task conditioning system were conducted toinvestigate impacts of the system on thermal comfort and productivity in a climate chamber of Kanto-Gakuin University, Japan. All subjects participated in "default condition test: 26C / 50% RH" at first.Then a half of the same subjects participated in "standard condition test: 26C / 50% RH", and theremainder subjects participated in "task-ambient test: 30C / 50% RH + TAC", just one week later again separately. Thermal, humidity, comfort sensations, and other psychological factors were investigated.

This paper presents the main results of a research on an individually controlled office environment. The research was carried out in a laboratory that counts on an air conditioning system with underfloor air supply and individual airflow control devices for personalized thermal comfort. The evaluation was based on quantitative and qualitative data acquired respectively by means of comfort variables local measurements and people participation. The main results refer to the thermal comfort parameters proper to the referred environment and parameters for the system operation.

This paper after its first chapter about commissioning, presents the methodology used in the first re-commissioning phase of the CAMET HVAC system, with its principles and facts.Commissioning is a unique opportunity, for all partners concerned, to learn a lot about the realbehavior of a HVAC system and to restore people's confidence in air conditioning.

An experiment was performed to determine whether the sensory pollution emitted from a bagfilter that had been used for 3 months in a suburban area in Denmark was influenced bydifferent ways of operating the air-handling unit (AHU). Samples of the used filter were preconditioned to simulate three operating conditions: (1) switched off overnight; (2) airflowreduced to 10% overnight; and (3) continuous 100% operation. Outside air passed through thesamples and the acceptability of the air after the filter was assessed by a panel of subjects.

The quality of air in the indoor environment is dependent on the nature and source of indoorpollutants and the performance of the ventilation system. Increased dilution in a tropical contextimplies a high energy penalty. This paper presents a novel method of addressing IAQ and energyissues. An innovative energy efficient method and means of air-conditioning for an independentcontrol of temperature and humidity of two different air streams has been developed.

The term air conditioning not only prescribes comfort temperature and the relative humidity,but also the quality of air inside the room. Indoor air quality (IAQ) has become a concomitantof air conditioning. The pollutants generated inside the room affect the quality of air inside theroom. The major pollutants considered are CO2, sulfur dioxide, toluene, etc. Monitoring andcontrolling of all the pollutants is cumbersome. CO2 is considered as the surrogate index ofpollutants. Appendix D of the ASHRAE standards 62-1999 recommends a ventilation rate of15 cfm per person.

Air supply diffusers used in air-conditioning systems can be classified as ceiling diffusers,side-wall diffusers, floor diffusers, jet nozzles and low velocity displacement diffusers. Fixedor adjustable slats are usually used to control airflow directions. Recently, swirling vanes areused in floor diffusers to create a swirling out-flow jet, so that more rapid mixing withambient air can be achieved.

The paper deals with a numerical investigation of the influence of ventilation and airconditioning on the distribution of pollutant concentrations in buildings. The model used is acoupled thermal and airflow model where the room is divided into 18 sub-zones.Temperatures and pressures are determined from the mass and energy conservation equationsin each sub-zone, while airflow rates between two adjacent sub-zones are determined from theBernoulli equation.

Split system air-conditioning units are commonly employed in residential buildings inthe tropics due to their convenience in terms of energy conservation, aesthetics,flexibility, acoustic performance and ease of operation. This paper presents ourfindings from a recent study of the IAQ and ventilation characteristics in a masterbed-room of a condominium unit in Singapore, employed with a split system airconditioningunit. The attached bathroom is equipped with an exhaust fan, whoseoperation and its impact on the resulting IAQ and ventilation characteristics was alsostudied.