TWO-LAYER SENSOR MATRIX AND DATA ACQUISITION SYSTEM DESIGN IN SPATIAL TEMPERATURE AND HUMIDITY MEASUREMENT

摘要

Spatial temperature and humidity distributions are very important for investigating the flow patterns of cooling air in a conditioned room. They are useful in the prediction of local discomfort for various air conditioning designs and provide designers with rapid quantitative information early in the design process. Because of high cost and less modifiability, commercial instruments have inhibited detailed and intensive research on the flow pattern measurement. Therefore, the re-design of the measurement system is considered essential. In this paper, we first design a humidity-to-frequency converter for the capacitance humidity sensor, and adopt a temperature sensor with a temperature-dependent duty cycle output. Without the analog to digital converter, a high-speed counter is enough to convert the digital signals to relative physical phenomena. Then, a two-layer matrix of sensing modules composed of the above-mentioned temperature and humidity sensor is constructed. Finally, a multi-channel data acquisition system is proposed to offer the temperature and humidity at any fixed position demanded by the user. Actually, the proposed measurement system is capable of giving a complete 4D (space and time) description of the temperature and humidity in the concerned environment.