## 4 Results and Discussion
This is reflected in the graphical representation of the heat pipe efficiency calculated by Equation (29) and presented in Figure 7 and shows an increase in the heat pipe efficiency with the heat pipe temperature and the magnetic field\". Figure 8: Thermal efficiency of hybrid system with PV-Th solar panels. Figure 7: Thermal efficiency of heat pipe evaporator with PV-Th solar panels. Similar observations were noted regarding the other key parameters of the hybrid system in Figures 4 and 10 at the different nanofluid concentrations, and in particular, in Figures 9 and 10 where it can be seen that the higher the magnetic field, the higher the thermal energy generated and dissipated into the heat transport fluid. Additionally, we noted that the higher the magnetic field, the higher the thermal efficiency of the hybrid system in question compared to the water as base heat transport fluid circulating beneath the PV solar panel. Similar observations have been noted for other nanofluid concentrations (10% and 20%). It is believed that the aforementioned observations were caused by the enhancement in thermal conductivity of the magnetic nanofluids and can be explained based on the interaction among the dispersed nanoparticles and how the behavior changes in the presence of a magnetic field. \"The phenomenon of the enhancement of thermal conductivity can be explained based on chain formation due to particle-particle interactions and alignment along the magnetic field ([PERSON] [12] and [PERSON] [21]), which resulted in the formation, conducting, and diffusing of heat. A higher magnetic field charge can cause heat transport  
Figure 10: Thermal efficiency of hybrid system with PV-Th solar panels with different magnetic fields. Figure 9: Thermal energy is generated by PV-Th solar panels with a different magnetic field. water-based nanofluid molecules to be attracted to each other and form clusters when passed through a magnetic field, and some of the physical properties, such as surface tension, viscosity, the dielectric constant, and electrical and thermal conductivity, were changed under the influence of the magnetic field, as reported by [PERSON] et al. [51], compared to no magnetic field. [PERSON] et al. [52] also found that the magnetic fields reduced the specific heat, increased the soaking degree and hydrophobicity of water to materials, depressed its surface tension force, and increased the refractive index and electrical conductivity. If the particles are loosely packed within the fibrils, as occurs with low magnetic fields or low concentrations, the effective volume of the fluid in between two consecutive particles within the chains is larger and thereby the chain's ability to conduct heat is low. As the magnetic field intensity increases, the force of attraction among the nanoparticles is also increased and reaches maxima at CMF. It is also believed that the aforementioned changes caused by the magnetization of the heat transport fluid and its thermophysical properties enhanced the thermal energy transferred to the heat transport fluid and, in turn, increased the PV-Th thermal efficiency as well as the hybrid system efficiency\". During this investigation, we observed that the nanofluid concentrations have a significant effect on the system's main characteristics, such as the thermal energy transferred to the heat transport nanofluid and the hybrid system thermal efficiency. Figures 11 and 12 have been constructed to illustrate this phenomenon. The results displayed in these two figures confirmed that the higher the nanofluid concentration, the higher the thermal energy transferred to the nanofluid compared to the water-based heat transport fluid. Furthermore, the same phenomena have been observed with the thermal efficiency of the hybrid system where the higher the nanofluid concentrations, the higher the hybrid system efficiency compared to water as the base heat transport fluid. These phenomena have been discussed and elaborated on in the literature, namely in references [31; 47; 48; 49; 50].