## 2 Materials and Methods
### Study of Liquid Hydrocarbon Characteristics  
2.5.1. Characterization of Materials  
The density and both kinematic and dynamic viscosity values at 50 and 80 \({}^{\circ}\)C were determined using a Stanbinger viscometer SVM3000 ([PERSON], Graz, Austria) according to ISO 12185:1996 and ISO 3104:1994, respectively. The pour point (T\({}_{\rm P}\)) was determined using a liquid low-temperature thermostat KRIO-T-05-01 (Termex, Kirov, Russia) according to ASTM D97-17b. The flash point was determined using PE-TVO device (Ekros, Saint-Petersburg, Russia) according to ISO 2592:2000. The water mass content was determined from the density difference using a separating funnel and an oil demulsifier. The ash content of the liquid hydrocarbon sample was determined according to ISO 6245:2001. The calorific value of the products was found from the results of complete combustion of the samples in an ABK-1 bomb calorimeter (Russian Energy Technologies, Moscow, Russia). The content of carbon, hydrogen, nitrogen, and sulfur was determined using a Flash 2000 CHNS analyzer (Thermo Fisher Scientific, USA). The pH value of the liquid hydrocarbon sample was determined using a SevenCompact S220 pH meter (Mettler Toledo, Columbus, OH, USA) with a glass electrode. The fractional composition of the liquid hydrocarbon sample was determined using ARNS-1E distillation apparatus for oil products (Neftekhimavtomatika, Moscow, Russia) according to ISO 3405-2013. The sample surface tension was measured by the ring tearing method (du Nuy method) using a K6 tensiometer (KRUSS, Hamburg, Germany) at 25 \({}^{\circ}\)C.  
The fractional composition was determined using ARNS-1E distillation apparatus for petroleum products (Neftekhimavtomatika, Moscow, Russia) according to ISO 3405-2013 *Petroleum products. Determination of distillation characteristics at atmospheric pressure. Thermal decomposition of the liquid hydrocarbon sample in an inert argon atmosphere was performed using a Netzsch STA 449 F3 Jupiter differential thermal analyzer ([PERSON], Selb, Germany). The analysis was carried out in a corundum crucible with a perforated lid up to 600 \({}^{\circ}\)C at a heating rate of 10 \({}^{\circ}\)C/min. The gas flow rate was 150 mL/min. The sample weight was \(\approx\)15 mg. All the experiments were conducted under atmospheric pressure. The parameters of the sample thermal conversion were evaluated using physical quantities (temperature, time and rate of thermal conversion) calculated graphically using TG and DTG curves. 2.5.2. Experimental Study on Atomization Characteristics of Pyrolysis Oil Jet  
High-speed visualization of jet characteristics (droplet velocities and spraying angle) and image processing were performed according to [26]. Image processing was performed using the ActualFlow software developed by Sigma-Pro (Novosibirsk, Russia) [27]. At the moment of the study area illumination with a laser pulse, the jet was recorded using a digital cross-correlation camera. The camera was installed perpendicular to the laser sheet plane. Figure 3 presents a schematic diagram of the experimental setup for recording a liquid hydrocarbon droplet jet after pneumatic spraying. Liquid hydrocarbons were supplied from the fuel tank using an air-operated diaphragm pump. The spraying agent was air supplied by the compressor to a pneumatic nozzle with internal mixing chamber (Figure 4). The jet of sprayed products was illuminated with a laser sheet. The pneumatic nozzle for liquid hydrocarbon spraying was made of stainless steel. The main sizes are shown in Table 1. The nozzle consists of a body with fuel and spraying agent inlets and two removable heads. They are attached by a thread. Liquid hydrocarbons flow through the inner channel to the mixing chamber where they are mixed with the spraying agent. Air flows through the inlet channel and then goes to the mixing chamber through the annular gap. The obtained fuel-air mixture is sprayed through the nozzle outlet. Figure 3: Schematic diagram of the experimental setup for liquid fuel spray recording.