| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 5.67 MB | Adobe PDF |
Advisor(s)
Abstract(s)
O caudal de ar, como outro qualquer tipo de caudal, existe quando uma determinada área se encontra com maior energia/pressão que outra. A correta medição do caudal de ar é um fator essencial para uma boa avaliação da qualidade do ar interior (QAI) e diminuição do consumo energético associado à ventilação. A QAI é um fator fulcral, sendo que uma das formas de garantir uma boa gestão do ar é através da ventilação, a qual é usualmente praticada através de uma máquina de fluxo. Em Portugal existe legislação que relaciona a QAI com o Caudal/renovações de ar efetuadas por espaço, sendo necessário um controlo bastante rigoroso do mesmo. Esta referida máquina de fluxo tem necessidade energética, sendo esta predefinida em projeto pelo caudal a transportar e rendimento da máquina. Por consequente, a má avaliação do caudal que é transportado implica um sobredimensionamento do equipamento (maior investimento) ou uma sobre utilização da máquina já dimensionada (diminuição do rendimento). Daqui surge a necessidade de um equipamento de medição calibrado, para a necessidade pretendida (caudal de ar). A calibração tem de ser efetuada em laboratório, para que seja possível medir e regularizar parâmetros que afetam o funcionamento do equipamento e se obtenha assim um menor erro e uma melhor certeza possível. Como tal, a criação de uma instalação para a calibração de equipamentos de medição de caudal de ar foi requisitada para este projeto. Começou-se por determinar a gama do caudal de ar a atravessar a instalação, compreendido entre 45 m3 /h a 5000 m3 /h, resultante da ventilação de edifícios de serviço e comércio. Conhecendo a gama de caudal de ar, pesquisaram-se equipamentos de medição deste caudal utilizados em ventilação, dos quais o balómetro e a “air station”, que serão calibrados na instalação projetada. Com a finalidade de os calibrar, realizou-se um estudo de métodos de calibração, concluindo-se que o mais favorável se trata do caudalímetro de referência, através de um conjunto de bocais. O dimensionamento dos bocais foi efetuado conforme a (AMCA 210-99 & 51-99, 1999) e através da ajuda da ferramenta “solver” do Excel. Foram propostas alterações a um túnel de vento existente, inicialmente projetado para a medição de velocidade, de modo a se obter uma instalação capacitada para a calibração de equipamentos de medição de caudal de ar. Foi então possível fazer o projeto da instalação e dos bocais, possível de ser implementado futuramente, mas com possíveis alterações/correções.
The air flow, like any other type of flow, exists when one area is at higher energy/pressure than another. The correct measurement of air flow is an essential factor for a good evaluation of indoor air quality (IAQ) and reduction of energy consumption associated with ventilation. The IAQ is a key factor, and one way to ensure good air management is through ventilation, which is usually done using a flow machine. In Portugal there is legislation that relates the IAQ with the flow/renovations of air carried out by space, being necessary a very strict control of it. This flow machine has an energy requirement, which is predefined in design by the flow to be transported and the efficiency of the machine. Consequently, the poor evaluation of the flow that is transported implies an overdimensioning of the equipment (higher investment) or an over utilization of the already dimensioned machine (reduction of the efficiency). From this arises the need for a calibrated measuring equipment, for the required need (air flow). Calibration has to be carried out in the laboratory in order to measure and regulate parameters that affect the operation of the equipment, so as to obtain the least error and the best possible certainty. As such, the creation of an installation for the calibration of air flow measurement equipment was requested for this project. It was first determined the range of air flow through the installation, from 45 m3 /h to 5000 m3 /h, resulting from the ventilation of service and commercial buildings. Knowing the range of air flow, we researched the measurement equipment of this flow rate used in ventilation, of which the balometer and the "air station" that will be calibrated in the projected installation. In order to calibrate them, a study of calibration methods was carried out, concluding that the most favorable is the reference flow meter, through a set of nozzles. The dimensioning of the nozzles was done according to (AMCA 210-99 & 51-99, 1999) and with the help of Excel's "solver" tool. Changes had been proposed to an existing wind tunnel, initially designed for the measurement of speed, to obtain an installation capable of calibrating air flow measurement equipment. It was then possible to design the installation and the nozzles, which could be implemented in the future, but with possible changes/corrections.
The air flow, like any other type of flow, exists when one area is at higher energy/pressure than another. The correct measurement of air flow is an essential factor for a good evaluation of indoor air quality (IAQ) and reduction of energy consumption associated with ventilation. The IAQ is a key factor, and one way to ensure good air management is through ventilation, which is usually done using a flow machine. In Portugal there is legislation that relates the IAQ with the flow/renovations of air carried out by space, being necessary a very strict control of it. This flow machine has an energy requirement, which is predefined in design by the flow to be transported and the efficiency of the machine. Consequently, the poor evaluation of the flow that is transported implies an overdimensioning of the equipment (higher investment) or an over utilization of the already dimensioned machine (reduction of the efficiency). From this arises the need for a calibrated measuring equipment, for the required need (air flow). Calibration has to be carried out in the laboratory in order to measure and regulate parameters that affect the operation of the equipment, so as to obtain the least error and the best possible certainty. As such, the creation of an installation for the calibration of air flow measurement equipment was requested for this project. It was first determined the range of air flow through the installation, from 45 m3 /h to 5000 m3 /h, resulting from the ventilation of service and commercial buildings. Knowing the range of air flow, we researched the measurement equipment of this flow rate used in ventilation, of which the balometer and the "air station" that will be calibrated in the projected installation. In order to calibrate them, a study of calibration methods was carried out, concluding that the most favorable is the reference flow meter, through a set of nozzles. The dimensioning of the nozzles was done according to (AMCA 210-99 & 51-99, 1999) and with the help of Excel's "solver" tool. Changes had been proposed to an existing wind tunnel, initially designed for the measurement of speed, to obtain an installation capable of calibrating air flow measurement equipment. It was then possible to design the installation and the nozzles, which could be implemented in the future, but with possible changes/corrections.
Description
Keywords
Caudal de ar QAI Equipamento de medição de caudal de ar Calibração Bocais e instalação Air flow IAQ Measuring equipment Calibration Nozzles and installation