Simulation of a new type gas-fired air-cooled air-conditioner

Energy and environment has been issues concerned all over the world. In China, the application of small size gas-fired air-cooled air-conditioner as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand, lack of water resources and environment-friendly working pairs. Especially, the new air-cooled air-conditioner has many advantages. In order to evaluate its cycle performance, the mathematical model of the new air-conditioner was presented.


The paper describes the numerical simulation of a novel ventilation cooling system. The ultimate aimof the mathematical model is to facilitate the design of the system for specific buildings and climates.The model directly takes account of time dependency in that the diffusion equation for the heat flow inthe fabric of the room is solved. This approach means that important parameters (e.g. ventilationrates and internal heat gains) can be arbitrarily specified as functions of time.

Study of a Photovoltaic-Thermal Hybrid Collector with Juxtaposition of Thermal Energy Production Functions

This work proposes a mathematical dynamic modeling of a PV-T bi-fluids collector prototype that willpermit electricity production and preheating air and/or hot water production.This study is realised in a bi-dimensional geometry according to some assumptions. The collector is discretizedalong the flow and the collector slope is taking into account in the radiative transfers equations.

Risk of indoor airborne infection transmission estimated from carbon dioxide concentration

Accurate mathematical models of airborne infection are needed to estimate the risk from secondary transmission of biological warfare agents. An equation has been derived by the authors : they determined the fraction of inhaled air that has been exhaled previously by someone in the building by using a CO2 concentration as a marker for exhaled-breath exposure.
There is a critical rebreathed fraction of indoor air below which airborne propagation of common respiratory infections and influenza will not occur.

The effect street dimensions and traffic density on the noise level at different heights in urban canyons.

Noise measurements were made at 10 locations in ‘canyon’ streets in Athens with aspect ratio (height/width) varying from 3:1 to 1:1. The main purpose of the measurements was to examine the vertical variation in noise in the canyons to indicate the natural

A model of photocatalytic air cleaner for analyzing the performance of removing vocs in indoor air and its applications

The Volatile Organic Compounds concentrations in indoor air tend to be higher than the level allowed by the standards or codes. Photocatalytic oxidation by employing UV radiation is a promising approach for the VOCs removal .The purpose of this paper is the development of a simple but effective model of photocatalytic oxidation air cleaner.With that model, the design and the selection of suitable photooxidation air cleaners and the measurement of their Volatile Oragnic Compounds removing effect can be easily conducted..

Air distribution within a ventilated room.

Aims to study the behaviour of airflow generated by multiple jets and introduced into a room. A finite volumes mathematical model was used in the study, in which the equations were linearised in implicit form and the domain was presented in its discrete elements using the finite volume method. The numerical simulation was performed by creating unstructured computational grids. Findings were compared to experimental data including an extensive series of measurement taken in a model environment setup in a laboratory.

On controlling indoor thermal and moisture content for an occupied building.

The focus of this paper is on controlling ventilation rate to provide acceptable temperature and relative humidity in the space being ventilated. To this end, a system of heat and moisture balance equations for building indoor and components is described. The system is solved numerically. Based on a series of indoor temperature and moisture measurements for our experimental house and well-mixed air distribution in room, moisture generation rate is estimated. The model is validated by simulating the experimental house. Good agreement between the simulated and measured results is obtained.

A simple computer code for estimating energy load in buildings as the result of mechanical ventilation.

Mechanical ventilation in buildings requires appropriate systems for heating and cooling. The costs of energy demand represent a high percentage of the global costs for climatisation. As a part of a project concerning these subjects the development of a computer code for evaluating energy load due to mechanical ventilation in buildings is in progress. The mathematical model is based on simplified equations to fit dynamically the psychometric curves. Inlet air flow rates are evaluated according to the more recent Italian regulations.