## 3 Results and Discussion  
The values of specific physical (PH) exergy of streams obtained on the basis of the developed model are compared with the ones presented in [2] in Table 1.  
For an open system, the physical exergy associated with a flowing stream of matter, having a specific enthalpy \(h\) and a specific entropy \(s\), is calculated as  
\[e^{PH}=(h-h_{0})-T_{0}(s-s_{0}) \tag{10}\]  
where \(h_{0}\) and \(s_{0}\) are the specific enthalpy and the specific entropy, respectively, of the same stream calculated at the dead state temperature (\(T_{0}\)) and dead state pressure (\(p_{0}\)). In this work, \(T_{0}\) and \(p_{0}\) were taken as +20 \({}^{\circ}\)C and 0.1 MPa, respectively. It could be observed that the relative difference of \(-0.090\%\) was obtained for the physical exergy of the air at the evaporator inlet. Moreover, the other results were equal to the data presented in [2]. The thermodynamic data (i.e., absolute temperature, pressure, and specific physical exergy) of the real cycle for the R134a refrigeration system are presented in Table 2. The values of absolute temperature estimated on the developed model completely coincide with the ones presented in [2]. As for the values of absolute pressure and physical exergy, the maximum relative difference between the authors' model and the one developed in [2] was equal to \(-0.47\) and \(-0.44\%\), respectively. The mass flow rates of the air as a secondary working fluid for the real cycle of the R134a refrigeration system calculated on the basis of the developed model contrast those \begin{table}
\begin{tabular}{l c c c} \hline \hline \multirow{2}{*}{**Stream**} & \multicolumn{3}{c}{\(e^{PH}\)**, kJ-kg\({}^{-1}\)**} \\ \cline{2-4}  & **Authors’ Data** & **[PERSON] and [PERSON] [2]** & \(\delta\)**, \%** \\ \hline EV, in & 1.137 & 1.138 & \(-0.090\) \\ EV, out & 2.285 & 2.285 & 0.000 \\ CD, in & 0.000 & 0.000 & 0.000 \\ CD, out & 0.168 & 0.168 & 0.000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Values of specific physical exergy of the secondary working fluids (air). \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Stream**} & \multicolumn{3}{c}{\(T_{r}\)\({}^{\circ}\)C} & \multicolumn{3}{c}{\(p\)**, bar**} & \multicolumn{3}{c}{\(e^{PH}\)**, kJ-kg\({}^{-1}\)**} \\ \cline{2-10}  & \multirow{2}{*}{**Authors’ Data**} & \multirow{2}{*}{**Moresuk**} & \multirow{2}{*}{**Authors’ Data**} & \multirow{2}{*}{**and**} & \multirow{2}{*}{**Authors’ Data**} & \multirow{2}{*}{**and**} & \multirow{2}{*}{**Authors’ Data**} & \multirow{2}{*}{**and**} & \multirow{2}{*}{**Authors’ Data**} & \multirow{2}{*}{**and**} \\  & & & & & & & & \\ \hline
1 & \(-25.00\) & \(-25.00\) & 0.00 & 1.060 & 1.065 & \(-0.47\) & 4.56 & 4.58 & \(-0.44\) \\
2 & 61.10 & 61.10 & 0.00 & 10.17 & 10.17 & 0.00 & 52.96 & 52.97 & \(-0.02\) \\
3 & 40.00 & 40.00 & 0.00 & 10.17 & 10.17 & 0.00 & 40.40 & 40.40 & 0.00 \\
4 & \(-25.00\) & \(-25.00\) & 0.00 & 1.060 & 1.065 & \(-0.47\) & 27.60 & 27.60 & 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thermodynamic values of the real cycle with R134a. shown in [2], as demonstrated in Table 3. It was found that the relative differences of estimation do not exceed +0.04%. The values of evaporator and condenser temperatures for the theoretical cycle and for the cycle with unavoidable exergy destruction are shown in Tables 4 and 5, respectively. It could be observed that the relative differences between the authors' model and the outcomes from [2] do not exceed +1.35%. The results above show that the model developed within this work is acceptable for the comparison of the results of the two aforementioned approaches for the estimation of avoidable parts of exergy analyses.