## 4 Results and Discussion  
### Results of Determining the Low-Temperature Properties of the Studied Samples  
Properties and composition of the studied straight-run DF samples are presented in Appendix A.  
The results of determining the low-temperature properties of the studied samples of straight-run DF, as well as blends of straight-run DF with depressant additives, are presented in Table 1: \(\Delta\) are presented in comparison with pure samples of straight-run DF without the involvement of depressants.  
According to requirements [5; 6] by CFPP, a sample of straight-run DF F\({}_{1}\) corresponds to summer brand of DF. A sample of straight-run DF F\({}_{2}\) does not meet the requirements [5; 6] for low-temperature properties. As shown by the results presented in Table 1, the use of the investigated DF samples in cold climatic conditions is impossible without the use of depressants. The unsatisfactory low-temperature properties of samples F\({}_{1}\) and F\({}_{2}\) can be explained by the fact that the samples are straight-run diesel fuel obtained by direct distillation of oil and do not contain any additives [8; 10].  
From the results presented in Table 1 it can be seen:  
* the addition of both depressants for both samples of straight-run DF resulted in an improvement in CFPP and PP;
* the addition of the A\({}_{1}\) depressant is on average more effective than the addition of the A\({}_{2}\) depressant;
* for a sample of straight-run DF F\({}_{1}\), the addition of a depressant A\({}_{1}\) allows to obtain fuel of winter brand, in accordance with the requirements [5; 6]; the addition of A\({}_{2}\) depressant does not change the DF brand (summer brand according to the requirements [5; 6]);
* for a sample of straight-run DF F\({}_{2}\), the addition of a depressant A\({}_{1}\) allows to obtain fuel inter-season brand, in accordance with the requirements [5; 6]; the addition of A\({}_{2}\) depressant does not allow obtaining fuel that meets the requirements [5; 6].  
Next, the low-temperature properties of blends of straight-run DF samples with n-paraffins P\({}_{1}\) and depressants were determined (Table 2).  
From the results presented in Table 2 it's clear that:  
* adding n-paraffins P\({}_{1}\) at a concentration of 0.50% wt. to the F\({}_{1}\)A\({}_{2}\) blend does not allow obtaining fuel that meets the requirements [5; 6] for all brands;
* adding n-paraffins P\({}_{1}\) in concentrations of 0.05-0.25% wt. to the F\({}_{1}\)A\({}_{2}\) blend, at concentrations of 0.10-0.50% wt. to a blend of F\({}_{2}\)A\({}_{2}\), as well as at a concentration of 0.05% wt. to the F\({}_{2}\)A\({}_{1}\) blend allows to obtain fuel that meets the requirements for low-temperature properties [5; 6] for summer brand of DF;
* adding n-paraffins P\({}_{1}\) at a concentration of 0.05% wt. to blends F\({}_{1}\)A\({}_{1}\) and F\({}_{2}\)A\({}_{2}\), as well as in concentrations of 0.10-0.50% wt. to the F\({}_{2}\)A\({}_{1}\) blend allows to obtain fuel that meets the requirements for low-temperature properties [5; 6] for winter-season brand;
* adding n-paraffins P\({}_{2}\) in concentrations of 0.05-0.50% wt. to the F\({}_{2}\)A\({}_{1}\) blend allows to obtain fuel that meets the requirements for low-temperature properties [5; 6] for inter-season brand;
* adding n-paraffins P\({}_{1}\) in concentrations of 0.10-0.50% wt. to the F\({}_{1}\)A\({}_{1}\) blend allows to obtain fuel that meets the requirements for low-temperature properties [5; 6] for winter brand.  
The obtained results are consistent with the results of studies about changes in the composition of diesel fuel [28; 29; 33].