The low efficiency of solar collectors can be mentioned as one of the problems in solar combined cooling, heating, and power (CCHP) cycles. For improving solar systems, nanofluid and porous media are used in solar collectors. One of the advantages of using porous media and nanoparticles is to absorb more energy under the same conditions. In this research, a solar combined cooling, heating, and power (SCCHP) system has been optimized by porous media and nanofluid for generating electricity, cooling, and heating of a 600 m2 building in a warm and dry region with average solar radiation of Ib = 820 w/m2 in Iran. In this paper, the optimal amount of nanofluid in porous materials has been calculated to the extent that no sediment is formed. In this study, solar collectors were enhanced with copper porous media (95% porosity) and CuO and Al2O3 nanofluids. 0.1%–0.6% of the nanofluids were added to water as working fluids; it is found that 0.5% of the nanofluids lead to the highest energy and exergy efficiency enhancement in solar collectors and SCCHP systems. Maximum energy and exergy efficiency of parabolic thermal collector (PTC) riches in this study are 74.19% and 32.6%, respectively. Figure 1 can be mentioned as a graphical abstract for accurately describing the cycle of solar CCHP.

Vegetation along the river increases the roughness and reduces the average flow velocity, reduces flow energy, and changes the flow velocity profile in the cross section of the river. Many canals and rivers in nature are covered with vegetation during the floods. Canal’s roughness is strongly affected by plants and therefore it has a great effect on flow resistance during flood. Roughness resistance against the flow due to the plants depends on the flow conditions and plant, so the model should simulate the current velocity by considering the effects of velocity, depth of flow, and type of vegetation along the canal. Total of 48 models have been simulated to investigate the effect of roughness in the canal. The results indicated that, by enhancing the velocity, the effect of vegetation in decreasing the bed velocity is negligible, while when the current has lower speed, the effect of vegetation on decreasing the bed velocity is obviously considerable.

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Due to the growing trend of energy consumption in the world uses of methods and new energy production systems with high efficiency and low emissions have been prioritized. Today, with the development of different systems of energy production, different techniques such as the use of solar energy, wind energy, fuel cells, micro turbines and diesel generators in cogeneration have been considered, each of these methods has its own advantages and disadvantages. Having a reliable energy generation system, inexpensive and availability the use of fuel cells as a major candidate has been introduced. Fuel cells converting chemical energy to electrical energy that today are one as a new technology in energy production are considered. In this paper fuel cell compression ratios 4, 4.1 and 4.2 at an ambient temperature of 298 K have been simulated and ultimately optimum ratio 4.1 for modeling has been selected. All components of cycle, including the stack of fuel cell, combustion chamber, air compressors, recuperator and gas turbine was evaluated from the viewpoint of exergy and exergy destruction rate was calculated by EES software.