Fossil fuels are exhaustible and their consumption causes environmental problems. As a result, renewable energy resources, specifically solar energy, should be utilized more to overcome the ...aforementioned issues. The biggest problem with renewable energy utilization is that their capital cost is very high. To tackle this problem, renewable energies should be coupled with conventional energy systems to lower the initial investment. In this paper, a parabolic trough collector is coupled with a conventional Rankine cycle to increase output power of the system by replacing its closed feedwater heaters. Also, to be able to use the system during the nights, a thermal storage system is added to the cycle. A complete energy, exergy and economic analyses are performed on the system and the results are compared with the base case condition. The results show that by using the proposed system, net generated power of the plant increases by 8.14%. Also, exergy analysis shows that in both cases boiler has the highest rate of exergy destruction. In general, due to huge amount of losses in the collector, exergy efficiency of the system decreases. Finally, economic analysis shows that simple payback time of the system equals to 1.5 years which is very low.
Capacitive Deionization (CDI) is an emerging technology in the desalination industry. It is critical to assess the parameters influencing desalination in capacitive deionization cells for ...understanding the deionization procedure and optimizing the desalination rate. Temperature is one of the critical parameters affecting desalination in this method. In the present study, Flow-by Capacitive Deionization (Fb CDI) was selected, and the dissolved ions were monovalent. The effect of temperature on the amounts of desalination, the charge displaced between the electrodes, and the cell performance coefficient were investigated. Donnan’s model was modified to model the Electrical Double Layer (EDL). The modified model involves the electrical diffusion layer within the micro-pores and the electric capacitance in the Stern layer. To investigate the primary functional parameters of capacitive deionization, the inlet fluid temperature was changed from 5 to 45 °C. The simulation results indicated that the amount of desalinated water or salt absorbed in electrodes and the amount of electric charge displaced between the electrodes decreased by the temperature while the cell performance coefficient or efficiency remained constant.
•An integrated system based on reversible solid oxide cell is proposed.•The highest and lowest net hydrogen production is associated with June and March.•Solar fraction peaks in June, July, August, ...aligning with high irradiation.•System's major consumer: electrolyzer; producer: photovoltaic cells.•The annual average overall efficiency of system is calculated as 23%.
This paper proposes and investigates an integrated system, centered around a reversible solid oxide fuel cell to meet power and fresh water demand of a small town. The proposed system is simulated in MATLAB and validated with experimental data. Subsystems including solar field, reversible solid oxide fuel cell, organic Rankine cycle coupled with ejector cooling, and zero discharge multi effect desalination system are modeled and analyzed in design condition. The electrical and thermal efficiencies of photovoltaic thermal system are calculated as 9.82 % and 53.27 %, respectively, while photovoltaic cell’s efficiency is 9.69 %. The organic Rankine cycle generates 451.5 kW and 1.31 MW for cooling and heating loads, respectively, with a net power of 450 kW. Freshwater production of desalination unit transpires at a rate of 9.6 kg/s in the effects, supplemented by an additional 13.5 kg/s in the spray evaporation tank, resulting in a calculated gain output ratio of 12.06 for the proposed system. The entire system has been examined during day and night throughout a year (taking one day for each month) with the assumption of system stability at every hour. Reversible solid oxide stacks switch between electrolyzer and fuel cell modes hourly, corresponding to hydrogen production or consumption across months. Monthly hydrogen dynamics are determined, showing peak production in June, minimal production in March, and negative values in January, February, November, and December. The total net hydrogen production over the entire year amounts to 22679 kg. The electrolyzer exhibits the highest power consumption, followed by the desalination cycle's electric heater, Reversible solid oxide cell’s electric heater and evaporator. Peak power production during daylight is from the photovoltaic system linked to solar irradiance, while fuel cells maintain a consistent 5 MW generation during night. In fuel cell mode, the system attains 27.5 % overall efficiency in cold months and 25.8 % in warm months, while operating as an electrolyzer results in an overall efficiency ranging from 3.7 % to 4.1 %. The calculated annual average overall efficiency is 17.29 %.
A novel solar power, water and hydrogen cogeneration plant with recovery of cryogenic energy is proposed in this paper to produce hydrogen and permeate water by gasification of Liquefied Natural Gas ...(LNG). A mathematical model is developed to simulate the system and an exergy and thermodynamic parametric analysis is carried out to investigate the effect of several thermodynamic parameters on overall system performance. A dynamic Reverse Osmosis (RO) desalination model is introduced to produce different permeate and feed water mass flow rates. By the results, about 26.8% of net produced power is recovered by a turbine locating in RO brine discharge. The exergy analysis showed that the maximum exergy is destructed by collectors and condenser, respectively. Also, among output streams, natural gas ejected by Natural Gas (NG) turbine has the maximum exergy output. Furthermore, CO2 turbine inlet pressure has an optimum value aimed to produce maximum production and net output power. The net output power, moreover, increases by rising the boiler and turbine inlet temperatures and NG inlet pressure, while it decreases by increasing condensation temperature. It is noteworthy that by increasing recovery ratio of RO unit, the permeate water production increases and hydrogen production rate decreases, by contrast.
•A novel cogeneration plant to produce power, water and hydrogen is introduced.•A dynamic RO desalination model is introduced for different permeate flow rates.•A recovery turbine is used to recover power consumed in RO system.•About 26.8% of net power produced by cycles is recovered by recovery turbine.•Increasing the RO recovery decreases hydrogen and increase permeate flow rate.
This research highlights the thermal and ventilation performance of a newly designed solar chimney in conjunction with a windcatcher and water spray system for a two-story office building in a warm ...and arid climate. The north façade of the building is a windcatcher, which, coupled with a solar chimney on the roof provide ventilation for both floors via a floor void with the smallest footprint. An experimental study comprising a reduced scale model and computational fluid dynamics (CFD) analysis were carried out to evaluate the cooling and ventilation potential of a solar chimney with and without the windcatcher functioning. The results show that, even on a hot and sunny day, the solar chimney coupled with a windcatcher and water spray system can provide reasonable thermal and airflow conditions for both floors without the need of wind force. The arrangement is able to reduce an average temperature of 5.2 °C and generate about 9 ACH in the peak hours of a day for the occupied space, as well as save 75% of the total cooling and 90% of the energy required for ventilation during the working time in peak summer.
•With integrated ventilation, solar chimney enhances ventilation of top floor.•Water spray in wind catcher paired with solar chimney is the best pre-cooling system.•Cooling and ventilation energies of building are reduced by 75% and 90%, respectively.•Small opening between top floor and chimney improves cooling efficiency of system.
•A novel system is proposed to recover waste streams in a steam power plant.•Energy, exergy and economic analyses are performed to study its feasibility.•The proposed system is capable of producing ...fresh water, hydrogen and hypochlorite.•The proposed system is also increases net output power of the system.•The results showed that the system is thermodynamically and economically feasible.
Power plants are one of the most energy consuming industries in the world. Therefore improving their performance could save a huge amount of energy and water. In this paper, a novel system is proposed to recover the wasted heat and water in a steam power plant and then exergy and economic analyses are applied to the system to study its feasibility. The results show that by using this recovery system, total output power of the system increases by 1.2%. The new system has the capability of producing 82.5kg/s fresh water from blowdown streams. It also converts the brine stream of desalination system into hydrogen and hypochlorite. The economic analysis shows that the payback time of the system is 0.68year which indicates that the system is very beneficial.
•Thermodynamic analysis of a hybrid system to produce electricity, heat and cooling.•Sensitivity analysis is performed on the most important parameters of the system.•A suitable integrated system for ...peak time is provided.
Utilizing renewable energies is the promising solution to the environmental problems which are brought about due to fossil fuel consumption. The fact that these kinds of energies are intermittent can be overcome with using energy storage systems. Wind energy coupled with compressed air energy storage systems is one of the best candidates in this respect. The main objective of this paper is to study the integration of this system with a Combined Cooling, Heating and Power cycle comprised of a gas turbine, an organic Rankine cycle and an absorption refrigeration system. Energy and exergy analyses are applied to the system and the effect of key parameters on the system performance are analyzed. The results show that under design condition, the system can generate 33.67kW electricity, 2.56kW cooling and 1.82ton per day hot water with a round trip energy efficiency of 53.94%. Also exergy analysis reveals that wind turbine, combustion chamber and compress air storage system have the highest amount of exergy destruction respectively. Finally, sensitivity analysis shows that parameters related to gas turbine are the most prominent parameters of the system which can change performance of the system considerably.
This study attempts to go beyond the conventional framework of the integrated solar transcritical CO2 power cycle works, aimed at further utilization of available exergy as much as possible. This ...paper proposed a novel system for hydrogen and fresh water production in which a Stirling engine used instead of a condenser, for the places with abundant access to solar radiation and sea, and least to freshwater sources. This proposal leads to further utilization of streams’ exergy through the system instead of wasting to the environment, and further power production by the engine followed by the higher products. The electrolyzer employed beside Reverse Osmosis (RO) desalination system, and takes full advantages of highly concentrated brine stream of desalination, eliminating the wastewater rejection through proposed system leading to attaining a near-ZLD approach in fresh water and hydrogen production. This reduces the adverse impacts of desalination’s wastewater on the environment. A thermodynamic and exergy analysis is carried out to compare the superiority of this study and investigate the effect of some key parameters on the overall performance of the system as well. The results showed that replacing the condenser by a Stirling engine reduces the exergy destruction through heat transfer from CO2 to an LNG unit. Exergy destruction was reduced from 16.7% to 8.8% for the above configuration for an ideal Stirling engine that exploits it to produce extra power which its minimum is at least 9 kW and 15 kW higher than CO2 and LNG power productions. Moreover, Entering RO brine stream, wasting 2.58 kW exergy, to the electrolyzer leads to NaClO and H2 production besides removing brine stream. In a power plant, sodium hypochlorite is used for disinfection of cooling systems and hydrogen can be used as a source of energy in fuel cells. An examination of some thermodynamic factors showed that higher CO2 turbine inlet pressure has an optimum value in producing fresh water and hydrogen, while the higher CO2 turbine inlet temperature slightly reduces the productions rate. The more recovery ratio also causes a sharp reduction in hydrogen production, whereas it has an optimum amount of fresh water production at recovery ratio equals to 0.47.
•A novel cogeneration plant including Stirling engine to produce water and hydrogen.•A dynamic RO model including recovery turbine for different permeate flow rate.•About 8% reduction in exergy destruction in the system using ideal Stirling engine.•More electrical power production, higher than both LNG and CO2 power cycle.•Electrolyzer-based ZLD approach by employing electrolyzer beside RO desalination.
The aim of this study is modeling a solar-air heater humidification-dehumidification unit with applying particle swarm optimization to find out the maximum gained output ratio with respect to the ...mass flow rate of water and air entering humidifier, mass flow rate of cooling water entering dehumidifier, width and length of solar air heater and terminal temperature difference (TTD) of dehumidifier representing temperature difference of inlet cooling water and saturated air to dehumidifier as its decision variable. A sensitivity analysis, furthermore, is performed to distinguish the effect of operating parameters including mass flow rate and streams’ temperature. The results showed that the optimum productivity decreases by decreasing the ratio of mass flow rate of water entering humidifier to air ones.Article History: Received: July 12th 2017; Revised: December 15th 2017; Accepted: 2nd February 2018; Available onlineHow to Cite This Article: Afshar, M.A., Naseri, A., Bidi, M., Ahmadi, M.H. and Hadiyanto, H. (2018) Modeling and PSO Optimization of Humidifier-Dehumidifier Desalination. International Journal of Renewable Energy Development, 7(1),59-64.https://doi.org/10.14710/ijred.7.1.59-64
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