Abstract View
Performance Characteristics of a Dual Stage Porous Tube Thermodiluter
AARON AVENIDO, Justin Koczak, Modi Chen, Francisco Romay, Russell Graze, Noah Bock, Darrick Zarling, TSI Incorporated
Abstract Number: 168
Working Group: Instrumentation and Methods
Abstract
When measuring aerosols from combustion and other high-temperature sources, it is necessary to dilute and condition the sample gas to reduce its temperature, dew point, and particle concentration while minimizing losses. To address this need, TSI has developed the Model 3098 Porous Tube Thermodiluter (PTT), a new accessory that integrates with the Model 3090 Engine Exhaust Particle Sizer spectrometerTM (EEPSTM) for a complete fast particle measurement solution.
The PTT consists of two independently-controlled dilution stages with a catalytic stripper positioned between them to remove volatile particles. Each dilution stage consists of a mass flow controller (MFC) and a porous tube diluter. The dilution air flows radially inward through the walls of the porous tubes, reducing losses. A third MFC controls the amount of flow removed between the dilution stages to keep the flow rate through the main section of the PTT constant regardless of dilution factor. This maintains constant residence time, thereby keeping particle losses consistent. The three MFCs allow the system to independently and dynamically control the primary and secondary dilution factors, and provide a stable and accurate total dilution factor from as low as 10:1 to as high as 500:1. The PTT control system is built into the TSI EEPSTM software, which provides a single user-interface for both dilution parameters and particle spectrometer control.
System performance of the PTT is presented, including accuracy of dilution factor across the full control range, and size-dependent system particle penetration and resulting particle loss correction function, which is included in the data processing algorithm. Additionally, particle size distribution and total solid particle number concentration of engine exhaust collected using the system are compared to those collected with EEPSTM, Scanning Mobility Particle SizerTM (SMPSTM), and condensation particle counter (CPC), using conventional ejector diluters and a catalytic stripper.