This paper studies the influences of a porous medium and wavy surface on natural convection of Cu-water nanofluid in an enclosed cavity based on the energy-flux-vector method. The effects of the Darcy number (Da), Rayleigh number (Ra), porosity (ε), nanoparticle volume fraction (ϕ), and geometric wave amplitude (α_w) on the energy flux vectors, isotherms, mean Nusselt number (Nu_m), total entropy generation (S_t), and Bejan number (Be) are examined. It indicates that given a low Ra and any value of the Da or a high Ra and a low Da, the energy flux vectors, isotherms, and entropy generation have similar distributions. Under such conditions, S_t and Nu_m have low values, while Be approaches unity. However, if Ra and Da have high values, the energy flux vectors form flow recirculation structures. Therefore, S_t and Nu_m increase, while Be decreases. As ε increases, S_t and Nu_m increase, while Be reduces. Finally, when a high Ra with a high Da is given, all Nu_m, S_t, and Be increase as α_w is increased.

The study utilizes the energy-flux-vector method to analyze the heat transfer characteristics of natural convection in a wavy-wall porous square cavity with a partially-heated bottom surface. The effects of the modified Darcy number, modified Rayleigh number, modified Prandtl number, and length of the partially-heated bottom surface on the energy-flux-vector distribution and mean Nusselt number are examined. The results show that when a low modified Darcy number with any value of modified Rayleigh number is given, the recirculation regions are not formed in the energy-flux-vector distribution within the porous cavity. Therefore, a low mean Nusselt number is presented. The recirculation regions do still not form, and thus the mean Nusselt number has a low value when a low modified Darcy number with a high modified Rayleigh number is given. However, when the values of the modified Darcy number and modified Rayleigh number are high, the energy flux vectors generate recirculation regions, and thus a high mean Nusselt number is obtained. In addition, in a convection-dominated region, the mean Nusselt number increases with an increasing modified Prandtl number. Furthermore, as the length of the partially-heated bottom surface lengthens, a higher mean Nusselt number is presented.

We analyzed the performance and financial feasibility of a compressed air energy storage (CAES) system in a potential region in Miaoli County, Taiwan, with the aquifer in the underground structure. We conducted a performance analysis of the system using the commercial software Flownex 9.0. Initially, a model for the Huntorf case in Germany was built, and its performance was compared with others for validation. The calculation results showed a deviation of about 1% in terms of efficiency, confirming the analytical capabilities and accuracy of the model. After verifying the system performance, the scale of output power was adjusted to 2 MW for initial development and subsequent planning. Then, geological characteristics were analyzed using COMSOL to establish a multiphase flow analysis model. This model evaluated the flow rate and pressure required for the operation of the CAES system. Lastly, a financial analysis was conducted based on the obtained results. The cost for system components was estimated, and the levelized cost of the proposed CAES system was evaluated. A comparison with other energy storage technologies was conducted to assess the financial feasibility of the analyzed CAES system.

In the present study, the case study of micro-siting for the campus of the Institute of Nuclear Energy Research (INER) is conducted. Results from the effect of weather data suggest that for the wind turbine system higher than 20 m, the effect of nearby building and wake on electricity production would be less important. The effect of different weather data on the generated annual electricity production (AEP) is consistent for the wind turbine higher than 20 m. The difference between the calculated and real AEP of INER-150 kW wind turbine is only 1.1%, which is much better than some previous studies. The good agreement is mainly due to the higher height of the INER-150 kW (50 m), more stable coming wind and smaller impact of building on the performance of power production. Considering the proactivity on the installation for the site in INER campus, the finalized decision on the selection of wind turbine is 1 kW system. The power generation-related data are collected and processed for the fine tuning of model parameters in the future.