The energy performance in a secondary loop of refrigerating systems using nanomaterials additives was investigated analytically. In order to predict the performance of these systems an analytical model was developed. A combination of the Effectiveness-Number of Transfer Units method and traditional heat transfer and fluid dynamics correlations was used to develop this model. The Performance Evaluation Criterion (PEC: is the ratio between the heat transfer rate and the pumping power required) was used to evaluate the benefit of using nanofluids instead of pure fluids. The model was validated using the data find in the literature. model was done for a tubular heat exchanger with different Reynolds number (laminar and turbulent regimes), and for different types of nanoparticles (Al2O3, Ag, Au, TiO, TiO2, Fe, Co, Cu, CuO, diamond and graphite) with different volume fractions. The results showed that the heat transfer rate significantly increased with the increase of nanoparticles concentration. But, the pumping power is also increased with the increase of nanoparticles concentration for laminar and turbulent flow regimes. PEC value results have shown that the energy performance is dependent on the type of nanoparticles: some of them (Al2O3, TiO, TiO2, diamond and graphite) were less efficient than the pure fluid while the others (Ag, Cu, Au, Co, CuO, and Fe) were more efficient. |
