## 4 Results and Discussion
### Analysis of the Effect of Adding N-Paraffins on the Depressant Additives Effectiveness
Also from the data provided in Table 4, it can be seen that adding n-paraffins P\({}_{1}\) to blends F\({}_{1}\)A\({}_{2}\) and F\({}_{2}\)A\({}_{2}\) leads to:  
* no change or deterioration in the depressant effectiveness in relation to CP (by 3-5 \({}^{\circ}\)C for the blend F\({}_{1}\)A\({}_{2}\) and at 0-3 \({}^{\circ}\)C for the blend F\({}_{2}\)A\({}_{2}\)), no change or deterioration in the depressant effectiveness in relation to PP (by 0-5 \({}^{\circ}\)C for a blend F\({}_{1}\)A\({}_{2}\) and 1-6 \({}^{\circ}\)C for the blend F\({}_{2}\)A\({}_{2}\));
* for blend F\({}_{1}\)A\({}_{2}\): at concentrations of 0.10-0.50% wt.--deterioration of the depressant effectiveness in relation to CFP (by 2-9 \({}^{\circ}\)C); at a concentration of 0.05% wt.--improving the depressant effectiveness in relation to CFP (by 1 \({}^{\circ}\)C);
* for blend F\({}_{2}\)A\({}_{2}\): in all concentrations--to improve the depressant effectiveness in relation to CFP (by 3-7 \({}^{\circ}\)C). In addition, it can be seen that with a decrease in the concentration of added n-paraffins:  
* for all blends, the negative effect on the depressant effectiveness in relation to CP and PP is weakened;
* for blends with an additive A\({}_{1}\) the positive effect on the depressant effectiveness in relation to CFP is weakened;
* for blends with an additive A\({}_{2}\) the positive effect on the depressant effectiveness in relation to CFP is enhanced. Also, from the data presented in Table 4, it can be seen that the addition of P\({}_{2}\) n-paraffins to the F\({}_{2}\)A\({}_{1}\) blend leads to:  
* deterioration of the depressant effectiveness in relation to CP (at 1-4 \({}^{\circ}\)C);
* no change or improvement in the depressant effectiveness in relation to PP (by 0-5 \({}^{\circ}\)C);
* improving the depressant effectiveness in relation to CFP (by 3-7 \({}^{\circ}\)C). In addition, it can be seen that with a decrease in the concentration of added n-paraffins weaken the negative effect on the depressant effectiveness with respect to CP, and the positive effect on the depressant effectiveness with respect to CFP and PP is enhanced. The revealed regularities are explained in the mechanism of depressants action: the introduction of additional heavy n-paraffins creates initial crystallization centers, triggers the action of a depressant, which prevents the growth and coarsening of these crystals, allowing fuel at more negative temperatures to pass through a standard filter element (improving the CFPP). A decrease in the positive effect with respect to CFP with a decrease in the concentration of added n-paraffins is due to the fact that at low concentrations of added high-melting hydrocarbons, the number of initial crystallization centers is insufficient, the effect described earlier is leveled. Regularities of a negative nature in relation to the effectiveness of the additive action on CP and PP are associated with the fact that the added heavy n-paraffins themselves are characterized by unsatisfactory low-temperature properties and, upon adding, determine (worsen) the CP and PP of blends. In addition, depressants are aimed at limiting the growth and aggregation of large crystals of n-paraffins, however, they do not prevent their appearance, as a result of which, with a decrease in temperature, the precipitated crystals of n-paraffins solidify and limit the fluidity of DF (deterioration of PP). With a decrease in the concentration of added high-melting hydrocarbons, the described effects with respect to CP and PP, similarly, are leveled. Difference in the regularities of the influence of the n-paraffins addition on the depressant additives A\({}_{1}\) and A\({}_{2}\) effectiveness can be explained as follows: the additive A\({}_{2}\) is weaker than the additive A\({}_{1}\) (Table 1) and in case of adding n-paraffins in high concentrations, its capabilities are not enough to simultaneously stop the growth of all crystallization centers, the effect of the additive is stronger at low concentrations of added high-melting hydrocarbons.