Inline quality monitoring of diesel exhaust fluid (AdBlue) by using the 3&amp;lt;i&amp;gt;ω&amp;lt;/i&amp;gt; method

Ralf E. Bernhardsgrütter,Christoph J. Hepp,Katrin Schmitt,Jürgen Wöllenstein,Hans-Fridtjof Pernau,Martin Jägle

doi:10.5194/jsss-10-5-2021

Abstract

Abstract. Because diesel combustion processes produce harmful detrimental nitrous oxides, the selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue) to reduce these emissions, is an important part in the cycle of the combustion process. Therefore, it is crucial to continuously monitor the quality of the diesel exhaust fluid to secure the ideal selective catalytic reduction. This article presents a platinum thin-film sensor using the 3ω method which is able to characterize the diesel exhaust fluid. By means of the 3ω method, information about the concentration of urea in water can be extracted. In this investigation, a digital lock-in amplification technique is used to execute the measurements. The results show that this sensor can determine the urea content within 1 % by weight. Moreover, besides the analysis of the 3ω signal, the 1ω signal is analyzed in depth to receive additional information about the temperature. Because the same structure can measure multiple parameters, such as concentration, temperature, and flow, the sensor might be a good alternative to the state-of-the-art diesel exhaust fluid sensor.

Highlights

The reduction and the control of pollutants produced by burning fossil fuels are a focus of governments and health organizations (de Beeck et al, 2013; Weingarten et al, 2019; Olabi et al, 2020)
Bernhardsgrütter et al.: Inline quality monitoring of diesel exhaust fluid (AdBlue) the urea concentration in water, and general deeper investigations related to the 3ω method
As described in the previous sections, both TDC and TAC can be determined by using the digital lock-in technique and Eq (5)

Summary

Introduction

The reduction and the control of pollutants produced by burning fossil fuels are a focus of governments and health organizations (de Beeck et al, 2013; Weingarten et al, 2019; Olabi et al, 2020). Reported DEF quality sensors are based on optical principles (Kumawat et al, 2014) and electrical (Fendri et al, 2015), ultrasonic (Gurusamy et al, 2017), and pulsed heating measurements (Schmitt et al, 2014). These sensors can often solely measure the concentration and sometimes the filling level in the tank. Bernhardsgrütter et al.: Inline quality monitoring of diesel exhaust fluid (AdBlue) the urea concentration in water, and general deeper investigations related to the 3ω method

Basic principle

Sensor

Setup and measurement protocol

Results and discussion

Conclusions