Geophysical investigations of the Wairakei Field

Geophysical studies of the Wairakei sector of the Wairakei–Tauhara geothermal system started shortly after exploration drilling began in the early 1950s. These investigations have made a major contribution in defining the boundary of geothermal systems and understanding the changes that have occurred in the reservoir as a result of fluid production. The most successful tools have been electrical resistivity methods for delineating the field, while microgravity, heat loss and groundwater level monitoring surveys were useful to interpret production-induced changes. Seismic, gravity and magnetic surveys had only limited success.     

Development of a new personal air filter test system using a low-cost particulate matter (PM) sensor

Abstract

The extensive use of air filters has encouraged advances in both the fabrication and characterization of air filter technology. An affordable and accessible means of assessing the quality of air filters is greatly needed because of the high demand for these filters. We developed a personal air filter test (PAFT) system for measuring filter pressure drop, efficiency, and quality of filtration. The PAFT system utilizes a PM sensor (Sharp, GP2Y1010AU0F) to measure filtration efficiency. PM sensor performance was evaluated and optimized to guarantee its suitability for this application. The sensor performance evaluation studied the output responses to sampling flow, particle diameter, and PM sources. We also improved the sensor’s sensitivity. The experimental results show that the sensor had no significant influence on the sampling flow. The sensor output was highly dependent on the particle size and PM source, but its response curves remained linear, which was an advantage for filter efficiency measurement. We measured the efficiency of nanofiber filters of various efficiencies, comparing the results to a reference efficiency as measured by a CPC (TSI, 3772). The test resulted in a filtration coefficient (K_f), which was used to correct the PAFT efficiency measurement results. We also conducted filtration efficiency tests on commercial mask filters and the results showed good agreement to the reference, with a small average error of about 2.5%. The complete design of the PAFT and experimental methods is discussed in detail.

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