Remote temperature radiometric identification of liquids

Abstract

Introduction. Most of the known methods cannot be used to remotely analyze a liquid, as there is no way to make contact between the researched solution and the measuring equipment. Atoms or molecules of any physical object with a temperature higher than absolute zero make spontaneous movements, which are transformed into electromagnetic fluctuations of thermal radiation. This radiation depends not only on the absolute temperature of the object but also on multiple qualities of the object as well as its interaction with the environment, including thermal interactions. Theoretical results. The analysis of dielectric cylindrical packages with researched liquids sealed inside was carried out based on quasioptical qualities of multilayer dielectric cylindrical lenses. The qualities of such lenses are related to parameters of both liquid and its package, therefore, it results in a possibility to distinguish liquids' parameters based on changes in penetrating electromagnetic waves' parameters. Experimental results. The radiometric methods of measurements in 8mm wavelength range for remote identification of liquids sealed in dielectric packages. Polarizing static thermal portraits of liquids in the temperature range from 0ºC to 25ºC were obtained. The differences in physicochemical characteristics of the liquids cause differences in their thermal portraits, which manifest in quantities of minimums and maximums, and different slopes of particular parts of the graphs, and can be recorded distinctly. The areas of phase transitions between solid matter and liquid, which are defined by the existence of negative slope of dependence between the received signal level and the temperature in the area between two maximums of thermal portrait (thermal capacity) can be identified during temperature measurements of liquids by radiometric methods. There are defining characteristics for each of the liquid groups (water-alcohol solutions, refined oil products), which are related to heat transmission thermodynamics. During natural heating of the cool liquids, a thin layer of ice or dew is created on the surface of the package, which is an additional layer for a dielectric lens that decreases the amplitude of the received signal but does not change the quality of different liquid's thermal portraits. Conclusions. The possibility of remote identification of liquids, which are similar in composition, for example, water solutions of ethanol with different concentration and refined oil products, is proved experimentally. Different types of packages that serve as an outer layer of a two-layered dielectric lens affect its quasioptical properties and therefore, the thermal portrait, which is being formed. Static thermal portraits show that main differences for liquids are found in the areas of minimal quantities of dependences of receiver signals' relative amplitudes, which occur in the thermal area and are connected to liquids' phase transitions (i.e. the existence of ice) in the package. Existence and size of droplets' layer depend on the specific heat of the liquid and its melting temperature. Graph analyzing of the experimental data (thermal portrait in a range of temperatures for water solutions of ethanol with different concentration) allows obtaining information about hydrogen bonds and solutions' structure, which matches with data obtained by more methods that are complex. The proposed method of remote identification of liquids that are sealed in a dielectric package is safe and environmentally friendly, as required of illuminating radiation does not exceed 20dB/кТ0. The sensitivity of the receiver used allows remote measurement of liquids' temperature, while it's sealed in dielectric package, regardless of electromagnetic wave distribution environment, with accuracy not less than 0,1ºC. The feasibility of the usage of polarization changes for remote identification of liquids, including flammable, based on changes in their thermal portrait's temperature, which are received by radiometric methods in 8-mm waveband range is experimentally shown. The broadband noise oscillator, which is being used, carries information about the liquid and the package.