## 3 Results and Discussions  
Absolute pressure is less commonly used as a pressure reference because it is always referred to as perfect vacuum or zero pressure. Therefore, absolute pressure is often used as a measurement parameter in specialized applications. Absolute pressure is usually expressed in bars or psi. The actual pressure at a given location is called the absolute pressure and is measured relative to the absolute vacuum (i.e., absolute zero pressure). The gage pressure is the difference between the absolute pressure and local atmospheric pressure. It can also be expressed as the relative pressure or effective pressure. Figure 6 presents a graph representing the absolute pressure values in the internal fluid volume, which shows the pressure changes occurring at the location of the fluid. The curves associated with temperature reveal the change in the absolute pressure of the fluid with temperature. As the fluid moved towards the hot side as it passed through the thin tubes, the absolute pressure increased as the temperature increased. This shows that there is a linear relationship between the temperature and pressure. Figure 6 shows the absolute pressure of the fluid volume inside the model. The absolute pressure of the fluid inside can vary between 199,953 Pa and 201,603 Pa. As the absolute pressure of the fluid passing through the thin pipes moves towards the hot side,  
Figure 5: Domain names of the model. Figure 6: Absolute pressure of internal fluid volume. the absolute pressure increases owing to the increase in temperature and can hover in the yellow-green region between 200,362 and 200,786 Pa. Figure 7 shows the absolute pressure of the fluid volume outside the model. Figure 7 shows the absolute pressure values for the external fluid volume. Compared with the internal fluid, the pressure changes in the external fluid were lower. The absolute pressure of the external fluid generally varies at lower values than those of the internal fluid. Changes in pressure values outside the volume were more stable and lower than the pressure changes in the internal fluid. Although the absolute pressure of the inner fluid varies between 199,953 Pa and 201,603 Pa, the absolute pressure of the outer fluid volume can vary between 101,327 Pa and 101,378 Pa. As the absolute pressure of the fluid passing through the body moves towards the hot side, the absolute pressure increases owing to the increase in temperature and can hover in the red-orange region between 101,368 Pa and 101,378 Pa. In summary, these graphs reveal the thermodynamic properties of the system by showing the changes in the absolute pressures of internal and external fluids. The pressure changes as the temperature increases, and the shape of the pressure differences between the internal and external fluids can be observed in these graphs. As shown in Figure 8, for an ideal gas, the compressibility factor will always be unity, equal to one. The compressibility factor, which is usually defined as \(\mathrm{Z=pV/RT}\), is unity for an ideal gas. It should not be confused with the isothermal compressibility coefficient. In most engineering work, the compressibility factor is used as a correction factor for ideal behavior. Figure 9 shows the simulation of the compressibility factor values of the model. The compressibility factor of R152a of the analyzed model is observed in Figure 9. If this value is exactly one, it is concluded that it is an ideal gas. The result of the ideal gas behavior of the R152a refrigerant used in the analysis is illustrated. How close R152a is to the ideal gas can be observed as a result of the analysis with the resulting scale. The fact that the values in the graph are close to one indicates that R152a generally behaves like an ideal gas and can provide the desired performance in the system. The scale range is observed between a minimum of 0.96608 and a maximum of 0.97272, and can be observed as being close to ideal gas behavior.