This present work has theoretically investigated coupled heat and mass exchangemechanisms in counterflow rotary dehumidifier with the mixed desiccant of LiCl and additives,used in air conditioning systems. Mathematical model has been derived, based on one-dimensionaltransfer model and Polyni potential theory (theory of water chemical potential)and solved, using digital computer. The profiles of temperature and absolute humidity distributionin the matrix have been obtained. Analysis shows, that the direction of mass transfer isopposite to positive water vapour partial pressure.
Computer simulation of building airtightness measurements shows the effect of changes inpressure distribution across the building envelope due to wind force and temperature differenceon measurement accuracy. The wide range of leakage distributions, wind directions and velocitiesconsidered give information on the boundaries of these uncertainties. For wind velocities on siteof v(site) ~= 3 m/s, the additional uncertainty in the flow rate at 50 Pa (Q50) found is comparable tothe uncertainty due to standard pressure gauges or operator (about 3%).
A patented, low energy, fresh air fan convector has been developed by a HVAC equipmentmanufacturer in conjunction with a leading controls supplier and a local University. It canheat, free cool, provide minimum ventilation air and carry out night cooling strategies in anintelligent self contained package. A number of full-scale tests have been carried out on theunit.
Residential ventilation systems can be categorized as supply, exhaust, or balanced systems.This effort focused on establishing a design methodology for central-fan-integrated supplyventilation systems. Air flow measurements were taken for 7.6 m lengths of 12.7 cm through22.9 cm diameter flexible ducts, with a 15.2 cm wall-cap, at duct pressures of -10 Pa to -120Pa. Using these measurements and field experience, a five-step method was developed as aguide for sizing and installing the ventilation system.
In order to estimate air change rates (ACH) on Natural Ventilation (NV) processes a number of factors should be known as general and openings dimensions, pressure distribution over the facades, internal heat sources (or sinks) and head losses. The atmospheric boundary layer (ABL) characteristics change with the terrain roughness and affect the pressure distribution. Construction features determine infiltration rates, flow regimes through openings and its head losses so affecting the internal airflow.
Isolation rooms for Tuberculosis in fifteen hospitals have been surveyed and measured in twophases. In phase 1 the isolation rooms in seven hospitals were checked ater the hospitalsrenovation construction had been finished. However in phase 2 all the design drawings of theair-conditioning and ventilation/exhaust system of isolation rooms in eight other hospitalswere checked and revised by ERLs engineer before starting construction. The survey itemsinclude ventilation rate ' static pressure ' temperature and humidity.
The present study introduces a humidity control apparatus which can hygienically and automaticlymaintain the appropriate humidity level of indoor air without either a water supply or drainage system.In humidification, the desiccant takes up water vapor from the outdoor air in the adsorption process,and releases it indoors by desorption. Therefore, no water supply is required to humidify. An apparatus havingno water supply is more hygienic, because it does not propagate bacteria and does notscatter the calcium and magnesium salts found in the water.
A test room was used to evaluate the impact of airflow parameters on the effectiveness of an air cleaning system. The room’s dimensions were nominally 11.2 m x 5.7 m x 2.7 m. The room has a drop-ceiling with space above for installation of above-ceiling air cleaning equipment and routing of ventilation ductwork. The HV AC system supplying the room could be turned on for constant flow (-349 ls·1) or left off to independently evaluate the effectiveness of the air filtration system.
Air temperature, air humidity and ventilation has been measured in a Swedish baroque castle. Results are presented for a measurement campaign comprising four periods under varying climatic conditions. A passive tracer gas method, known as the homogeneous emission technique has been used to measure the ventilation rates and air distribution in the building. As the palace is essentially unheated, wind pressure is the main driving force for ventilation. The air change rate is highly varying and differs considerably in different parts of the building (0.5-1.5 ACH).
This paper describes a numerical method for the determination of the effective depth of fresh air distribution in rooms with single-sided natural ventilation. The numerical method involves predicting air flow and the local mean age of air. The renormalisation group two-equation model of turbulence is used with the conservation equations of mass, momentum and energy to predict turbulent buoyancy-induced room air flow. The local mean age of air is then obtained from the solution of air flow equations together with the transport equation for the age of air.