A PULSED CONDENSATION PARTICLE COUNTER FOR LOW-COST MONITORING OF ULTRAFINE AIRBORNE PARTICLES

一种脉冲凝结粒子计数器 超细空气颗粒物的低成本监测 摘要 该项目将设计、开发和验证一种新的监测数字浓度的方法 空气中的细小和超细颗粒物。超细颗粒特别与健康有关，但却是 目前使用的低成本传感器无法检测到。我们的方法是脉冲凝聚粒子 使用绝热膨胀和单粒子计数相结合的计数器。具有现代光学技术 在传感器上，单颗粒计数是非常可行的，并且比总体测量更精确 以前的自动绝热计数器。我们的分析表明，我们的新方法应该更多 比现在使用的层流冷凝方法更节能，因为不需要加热或冷却 组件是必需的。我们的目标是一种价格实惠(3000美元)的便携式仪器，用于测量 颗粒数浓度具有已知的准确度和精确度，并弥合了 低成本的“公民科学”设备和研究级仪器。 这个第一阶段的项目将评估我们作为低成本传感器概念的可行性，通过建模和 做实验。它解决了关键方法组件，即系统规模、扩充率、 加湿和光学检测。数值模拟将检验由以下因素引起的饱和度比 在存在热和水蒸气从墙壁传输的情况下的膨胀，以及这种膨胀如何随 展开体积的纵横比。此建模将指导关键组件的设计，这些组件 然后将用已知大小和组成的实验室气雾剂进行建造和测试。该项目将 检查对凝聚扩大的颗粒进行光学检测的经济高效的方法，包括 巧合修正。这些组件将使用现有的电子设备进行测试，这些 实验数据将为估计准确度、精密度、尺寸、重量、功耗和 全套装系统的成本。

A PULSED CONDENSATION PARTICLE COUNTER FOR LOW-COST MONITORING OF ULTRAFINE AIRBORNE PARTICLES ABSTRACT This project will design, develop and validate a new approach for monitoring the number concentration of fine and ultrafine airborne particles. Ultrafine particles are specifically implicated in health, and yet are not detected by currently-used low-cost sensors. Our approach is a Pulsed Condensation Particle Counter which uses adiabatic expansion combined with single particle counting. With modern optical sensors, single particle counting is quite feasible, and is more precise than the ensemble measurements of prior automated adiabatic counters. Our analysis shows that our new method should be much more energy-efficient than the laminar flow condensation methods now used, as no heating or cooling of the components is required. Our target is an affordable ($<3000), portable instrument that measures the particle number concentration with known accuracy and precision, and that bridges the gap in between the low-cost “citizen science” devices and research-grade instruments. This Phase I project will assess the feasibility of our concept as a low-cost sensor through modeling and experiment. It addresses the critical method components, namely system sizing, expansion rate, humidification and optical detection. Numerical modeling will examine the saturation ratio resulting from expansion in the presence of heat and water vapor transport from the walls, and how this varies with the aspect ratio of the expansion volume. This modeling will guide the design of critical components, which will then be built and tested with laboratory aerosols of known size and composition. The project will examine cost-efficient means of optical detection of the condensationally enlarged particles, including coincidence corrections. These components will be tested using existing electronics, and these experimental data will provide a basis for estimating the accuracy, precision, size, weight, power use and cost of a fully packaged system.