In this investigation, a hybrid energy conversion system is proposed and evaluated for energy, exergy, and environmental criteria for generating power and freshwater. The system comprises of a Humidifier Dehumidifier Desalination (HDD) system for producing freshwater, an organic Rankine cycle system for generating electric power, and a solar Parabolic Trough Concentrator for absorbing solar energy as the desalination heat source. Different working fluids including Al2O3, Cu, CuO, TiO2, and MWCNT nanoparticles in oil as the base fluid are examined. The influence of different nanofluids on the performance of the system is investigated as the main goal of this study. Environmental impacts of the suggested system are studied. Results show that the thermal efficiency of the Parabolic Trough Concentrator was with the application of Cu/oil nanofluid as about 62.4%. It is illustrated that the amount of freshwater production can be increased by raising the nanofluid concentration. The freshwater production varies between nearly 15.28 kg/h to 15.46 kg/h with the application of nanofluid. The organic Rankine cycle net work and total efficiency improved with increasing nanofluid concentration. Also, it can be concluded that the application of MWCNT/oil with a concentration of 5% volume fraction has shown the highest exergy efficiency of 4.7%. It was concluded the suggested desalination system with application of the solar organic Rankine cycle system, in addition to producing fresh water and power, significantly reduced amounts of CO2 emissions in the environment. Finally, it should be mentioned that the ideal system was analyzed and the gains from the use of nanofluids are very small.

The goal of the present paper is the investigation of a solar desalination system with an organic Rankine cycle system for power and freshwater production. This system is an environmentally friendly technology that is able to utilize solar energy properly in a novel cogeneration application. A parabolic trough concentrator with a smooth and corrugated receiver was employed as the heat source of the desalination system. A humidifier–dehumidifier desalination technology was used for producing freshwater. The electricity is produced by an organic Rankine cycle which is fed both by the solar field and by the hot brine. The present analysis is performed by using a detailed numerical model which is validated by experimental literature data. Based on the final results, the corrugated tube has a maximum performance of 66.59%, and it is more efficient than the smooth tube with 63.11%. The average freshwater productions were estimated equal to 13.09 kg hr −1 and 12.71 kg hr −1 for the corrugated and smooth tubes, respectively. The maximum net work production is found at 7.57 kW with R113, while the less efficient working fluid is R134a. It was found that the application of the developed desalination system leads to the production of high amounts of fresh water and a significant reduction of the equivalent CO 2 emissions.

In the current study, a solar-driven organic Rankine cycle (ORC) system was thermodynamically, economically and environmentally investigated. A focal point concentrator with two different cavity-shape receivers was investigated as the ORC heat source. More specifically, the cylindrical and the hemispherical cavity receivers were examined and compared as the most usual and promising choices. MWCNT/oil nanofluid and R113 were used as the solar heat transfer fluid and ORC working fluid respectively. The main aim of this research is an investigation of different cavities in the solar dish and the investigation of the impact of the use of nanofluids in the solar system by different points of view. The results of this work showed that the hemispherical cavity receiver with nanofluid is the most efficient choice with 21.4% system efficiency, while the use of pure thermal oil in the hemispherical cavity leads to 18.9%. On the other hand, the use of the cylindrical cavity leads to 17.8% and 15.8% system efficiency with nanofluid and pure thermal oil respectively. The levelized cost of electricity (LCOE) was 0.077 €/kWh and 0.076 €/kWh for the cylindrical and hemispherical cavity receiver respectively. Moreover, it was concluded that the solar ORC system with the hemispherical cavity receiver as the ORC heat source had resulted in more positive environmental influence related to the cylindrical one.

Today, application of cavity receivers in solar concentrator systems is suggested as an interesting and novelty research subject for increasing thermal performance. In this research, a parabolic trough concentrator (PTC) with a rectangular cavity receiver was energetically investigated. The cavity receiver was studied with smooth and corrugated tubes. Different solar heat transfer fluids were considered, including water, air, and thermal oil. The effect of different operational parameters, as well as structural parameters, was investigated. The results showed that the linear rectangular cavity receiver with corrugated tube showed higher amounts of the absorbed heat and energy performance compared to the smooth tube as the cavity tube. Thermal performance of the rectangular cavity was improved using the application of water as the solar heat transfer fluid, which was followed by thermal oil and, finally, air, as the solar heat transfer fluid. Finally, it could be recommended that the rectangular cavity receiver with smooth tube using air as the solar heat transfer fluid is more appropriate for coupling this system with a Bryton cycle, whereas the rectangular cavity receiver with the corrugated tube using water or oil as the solar heat transfer fluid is recommended for achieving higher outlet temperature of the heat transfer fluid.

In this study, a solar parabolic trough concentrator (PTC) was evaluated as a heat source of a power generation system based on energy (E1), exergy (E2), environmental (E3), and economic (E4) analyses. Various configurations of power generation systems were investigated, including the solar SRC (SRC) and solar ORC (ORC). Water and R113 were used as heat transfer fluids of SRC and ORC system, respectively. It should be mentioned that the proposed solar systems were evaluated for providing the required power of a mobile house in an emergency condition such as an earthquake that was happened in Kermanshah, Iran, in 2016 with many homeless people. The PTC system was optically and thermally investigated based on sensitivity analysis. The optimized PTC system was assumed as a heat source of the RC with two various configurations for power generation. Then, the solar RC systems were investigated based on 4E analyses for providing the power of the mobile house based on various numbers of solar RC units. It was concluded that the solar SRC system could be recommended for achieving the highest 4E performance. The highest value of its energy efficiency was found at 24.60% and of his exergy at 26.37%. On the other hand, the ORC system has energy and exergy efficiencies at 17.64% and 18.91%, respectively, which are significantly lower than the efficiencies of the SRC system. The optimum heat source temperature for the SRC system is found at 650 K, while for the ORC system at 499 K. Moreover, the best economic performance was found with the SRC system with a payback period of 7.47 years. Finally, the CO2 mitigated per annum ( $$\varphi_{{{\mathrm{CO}}_{2} }}$$ ) was estimated at 5.29 (tones year−1), and the carbon credit ( $$Z_{{{\mathrm{CO}}_{2} }}$$ ) was calculated equal to 76.71 ($ year−1).

In the current study, a solar desalination system was energetically and exegetically investigated using a focal point concentrator as the heat source of the desalination system. The desalination system consisted of photovoltaic thermal (PV) panels and Humidification Dehumidification Desalination (HDD) systems. The effect of nanofluid application as the solar working fluid on the desalination performance was investigated as the main objective of this study. Optical and thermal analyses of the solar desalination system were conducted by SolTrace and Maple software, respectively, whereas exergy analysis of the solar desalination system was performed by writing codes in the Maple software. Different oil-based nanofluids were used as the solar working fluids including Al2O3/oil, Cu/oil, CuO/oil, TiO2/oil and MWCNT/oil. Also, the influence of different PV-HDD parameters including water flow rate and water to air flow ratio was considered on the performance of the solar desalination system. The results revealed that the cavity heat gain and thermal efficiency increased with increasing nanofluid concentration for all of the investigated nanofluids. Also, the Cu/oil nanofluid showed the highest thermal performance among all of the nanofluids. Exergy gain and exergy efficiency of the investigated solar system decreased with increasing nanofluid concentration. Moreover, the Cu/oil nanofluid resulted in the lowest exergy efficiency compared to other investigated nanofluids. The application of the Cu/oil nanofluid with higher nanofluid concentration can be suggested for producing the highest amount of the freshwater production, and the lowest gain output ratio of the desalination system.

AbstractIn the present investigation, a solar parabolic trough concentrator (PTC) with a linear cavity was examined by using a developed numerical model. More specifically, a V‐shape cavity receiver was studied in this work as a new and alternative design. The use of a cavity in a PTC is a very promising idea because it leads to high efficiency and to low investment cost. Up today, the emphasis in the use of cavities is given in dish concentrators and so there is a need for investigation of cavities also in linear concentrators. Different dimensional and operational parameters of the PTC with a V‐shape cavity were considered. More specifically, the position, aperture area, and the tube diameter of the V‐shape cavity, solar irradiance, inlet temperature level, and mass flow rate were evaluated based on sensitivity analysis. The results revealed that the highest optical performance was attained when the cavity was placed at the PTC focal line. Moreover, it is found that there is an optimum cavity aperture area to determine the greatest thermal efficiency. For the optical errors of 5, 10, 15, 20, and 35 mrad, the optimum cavity aperture wide was calculated at 5, 5, 6, 7, and 8 cm, respectively, with the tracking error to be 0°. The highest thermal performance has found when the collector operates with low inlet temperature, high flow rate, high solar irradiation level, and small cavity tube diameter.

In this research paper, a hybrid solar desalination system has been employed. The hybrid solar desalination system includes photovoltaic thermal panels, solar dish concentrator, and humidification-dehumidification desalination unit. The humidification-dehumidification desalination unit comprises a closed-air open-water flow configuration, and the solar dish concentrators are utilized for water heating. Examination of three different shapes of cavity receiver including cylindrical, cubical and hemispherical, as the solar dish absorbers, was carried out. Thermal oil was considered as the solar working fluid. The absorbed solar heat was transferred to the desalination unit using a heat exchanger. In the hybrid solar desalination, photovoltaic panels were used to generate the required power. Water flow was considered at the back of the photovoltaic panels for preheating and improving the photovoltaic efficiency. The principal aim of the current study is to propose hybrid solar desalination system to generate power, and produce freshwater. The solar desalination's performance was examined in terms of various solar dish parameters and different humidification-dehumidification desalination parameters. Examination of various solar dish parameters, including the solar working fluid's inlet temperature and the cavity shapes, was carried out. Also, some humidification-dehumidification desalination parameters, including the water to air flow ratio and the water flow rate, were considered. The effects of these four parameters were investigated on the water production and the gain output ratio. Based on the results, it was found that there was an increase in the production of freshwater by raising the water flow rate, decreasing the solar working fluid inlet temperature and increasing the air flow rate. Besides, there was an increase in the gain output ratio by increasing the water flow rate, increasing the inlet temperature, and increasing the air flow rate. Finally, the highest freshwater production and lowest gain output ratio were resulted by the hemispherical cavity receiver.

— In this work, three strategies of CO2 reduction including energy saving, carbon separation, and storage as well as utilizing alternative materials in detail have been reviewed. In case of energy saving approaches, shifting to more efficient process shows the best results since potentially mitigates almost 20% of CO2 emissions in the process. Carbon capture and storage (CCS) is also considered as an effective way to avoid release of CO2. However economical and technical challenges still play as remarkable obstacles against implementing such processes in cement plant. As far as alternative materials are the case, utilizing waste-derived fuel (WDF) and industrial by-products instead of conventional fuels and materials result in significant emission mitigation. Index Terms — Alternative materials, cement plant, CO 2 emissions, CO 2 mitigation, global warming I. I NTRODUCTION Carbon dioxide is the most important and abundant gas among all GHGs which have the highest contribution in global warming phenomenon. Thus, finding promising approaches to mitigate CO

The use of process systems engineering tools, such as process modeling software enable the alternative generation of more efficient and sustainable processes. This paper presents the simulation of cement process using alternative fuels to replace coal. The process modeling is performed using Aspen HYSYS. Simulation results revealed that the substitution of fuel oil, natural gas and palm kernel shell for coal had a significant contribution for emission reduction in cement industry. The emissions for the base case scenario found to be 40,317 kg/h CO 2 , 806 kg/h NO 2 and 146.8 kg/h SO 2 . Utilizing fuel oil mitigated 22% of CO 2 and 92% of NO 2 but increased 232% of SO 2 emissions. Altering coal to palm kernel shell resulted in 46.16% of CO 2 , 73% of NO 2 and 68% of SO 2 emission reduction. In the best case 45.64 % reduction of CO 2 emissions was achieved by replacing coal to natural gas and neither NO 2 nor SO 2 was generated. Key words : Cement plant; Process simulation; Aspen HYSYS; Alternative fuels; Air pollution reduction