Temperature Fields of the Droplets and Gases Mixture

Roman S Volkov,Ivan S Voytkov,Pavel A Strizhak

doi:10.3390/app10072212

Abstract

In this research, we obtain gas–vapor mixture temperature fields generated by blending droplets and high-temperature combustion products. Similar experiments are conducted for droplet injection into heated air flow. This kind of measurement is essential for high-temperature and high-speed processes in contact heat exchangers or in liquid treatment chambers, as well as in firefighting systems. Experiments are conducted using an optical system based on Laser-Induced Phosphorescence as well as two types of thermocouples with a similar measurement range but different response times (0.1–3 s) and accuracy (1–5 °C). In our experiments, we inject droplets into the heated air flow (first scheme) and into the flow of high-temperature combustion products (second scheme). We concentrate on the unsteady inhomogeneous temperature fields of the gas–vapor mixture produced by blending the above-mentioned flows and monitoring the lifetime of the relatively low gas temperature after droplets passes through the observation area. The scientific novelty of this research comes from the first ever comparison of the temperature measurements of a gas–vapor–droplet mixture obtained by contact and non-contact systems. The advantages and limitations of the contact and non-contact techniques are defined for the measurement of gas–vapor mixture temperature.

Highlights

Gas–vapor–droplet techniques are widely used in the industry [1,2,3,4,5,6]
We analyzed the difference between the experimental results of the high-speed optical measurement (LIP) and thermocouple measurements typical of industrial power installations
The experiments have shown that the differences between the temperature measurements in the experiments with air flow and combustion products are significant

Summary

Introduction

Gas–vapor–droplet techniques are widely used in the industry (scrubbers, rectification towers, gas–vapor heat transfer agent generators, flame and thermal water treatment, etc.) [1,2,3,4,5,6]. The main barrier to the development of high-temperature gas–vapor–droplet techniques is the lack of knowledge on complex interdependent heat exchange and endothermic phase transformations occurring when droplets and vapor travel in high-temperature gas flows. Another important aspect of an efficient gas–vapor–droplet technique is the homogeneous heating or evaporation (depending on technical requirements) of droplets throughout the contact chamber. This is quite difficult to achieve due to massive thermal gradient and limited size of the chamber. The efficiency of such installations, blocks, and units decreases significantly

Objectives

Results

Conclusion