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Combined heating and power (CHP) systems can be a favorable addition to the geothermal power plants since the generated heating commodity can be addressed for wide-range of mountainous districts. Regarding this consequential demand, two innovative CHP systems for the Sabalan geothermal in Iran are designed which were based on organic Rankine cycle (ORC) and Kalina cycle (KC). The plausibility of the introduced monolithic CHP systems is examined from thermodynamic and economic vantage points. Later, multi-criteria optimization via genetic algorithm procedure is accomplished considering major thermodynamic and economic parameters as objective functions. It was exhibited that the recommended ORC-based CHP system could generate overall optimum heating load and net electricity of 5151 kW and 3697 kW, correspondingly as well as achieving energetic efficiency of 61.38% and exergetic efficiency of 36.91%. On the other side, the KC-based CHP system generated overall heating load and net electricity of 2867 kW and 3912 kW, correspondingly, achieving energetic efficiency of 46.12% and exergetic efficiency of 32.52%. The outcomes of the second-law analysis portrayed that among all constituents, condenser attributed as the utmost destructive part of the systems due to the regasification processed firstly occurred through this constituent, followed by the generator. Also, to examine how the introduced set-ups react to any external disturbances, a thoroughgoing sensitivity examination around the basic operating input parameters was fulfilled. It is discovered that the energetic efficiency of the ORC-based CHP system could be maximized with condensation temperature, whilst the exergetic efficiency of the KC-based CHP system could be maximized with ammonia concentration.

Multigeneration systems (MGSs) driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based MGS is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas (LNG) as cold energy recovery. The system is composed of an organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), an LNG power generation system, and a proton exchange membrane (PEM) electrolyzer system. To demonstrate the feasibility of the proposed MGS, energy, exergy, and exergoeconomic analysis are employed as the most effective tools for the performance assessment of the system. It is found that the proposed MGS can produce cooling capacity, heating capacity, net output power, and hydrogen of 1020 kW, 334.8 kW, 1060 kW, and 5.43 kg/h, respectively. In this case, the thermal efficiency, exergy efficiency and total SUCP (sum unit cost of the product) of the MGS are calculated 38.33%, 28.91%, and 347.9 $/GJ, respectively. Furthermore, condenser 2 is introduced as the main source of irreversibility of the proposed MGS by exergy destruction ratio of 58.98%. Moreover, a comprehensive parametric study is carried out and it is concluded that the SUCP of the system can be optimized based on the geothermal inlet temperature. In addition, it is demonstrated that a higher thermal efficiency can be obtained by increasing the turbine 2 expansion ratio, evaporator temperature, and geothermal temperature or decreasing of the generator terminal temperature difference, turbine 1 expansion ratio, pump 3 pressure ratio, and condenser temperature. In the same vein, a higher exergy efficiency can be attained at high turbine 1 expansion ratio, turbine 2 expansion ratio, evaporator temperature, and pump 3 pressure ratio or low generator terminal temperature difference, geothermal inlet temperature, and condenser temperature.

This study aims to precisely model vapor phase concentration and bubble pressure in correlating alcohol-hydrocarbon mixtures to accurate assessment with effects from literature by employed Patel-Teja equation of state and together with Wong-Sandler mixing rules. Even though other intricate equations have been used for some selected systems, it is the first time that a systematic approach for measuring hydrocarbon-alcohol mixtures in the range of low to moderate pressures has been practiced by this research. Results show that models employed in this work, average-absolute deviations are fewer than the previous EoSs for alcohol-hydrocarbons binary mixtures. The complex models calculate bubble pressure and vapor phase concentration respectively with 2.25% and 3.25% of average-absolute deviations, whiles our models show a better result for them (respectively, 0.00 % and 0.47% averagely).

Liquid air energy storage (LAES) is a promising but under-developing electricity storage concept for large-scale applications, which has gained a lot of attention in recent years. No geographical restrictions, acceptable cost-effectiveness level, and high energy density are some of the main advantages of this technology. On the other hand, the immature state-of-the-art, and lower power-to-power round-trip efficiency compared to other competitors are referred to as its main drawbacks which should be addressed for the successful development of this concept. The current research proposes a novel hybrid design for the LAES to improve its electrical efficiency and to introduce it as a multi-generating unit being capable of tri-generation of power, heat, and potable water. The proposed hybrid system results in an overall efficiency of over 71% which is already ∼23% better than the conventional design of a stand-alone LAES. Thermodynamic analysis of the proposed hybrid system is performed; the simulation results are validated using the existing data in the literature. The multi-objective optimization algorithm is developed to optimize the system configuration and operating characteristics. 88.6 MWh off-peak renewable-based electricity is stored during 8 h to provide 52.8 MWh electrical energy during 4 h of the peak period. Also, 59 m3 potable water and 938.8 m3 hot water are produced during 12 h of system operation.

Thermal efficiency and emission of a gas-turbine cycle were improved through consideration of heat and mass recirculations. In this regard, three potential scenarios were investigated: using lone mass circulation, only heat recirculation, and both types of recirculation at the same time. In each scenario, the maximum potential improvement was found by multi-objective optimization. Furthermore, in the case of only heat circulation scenario, the best heat recirculator was chosen by comparing a tubular with a plate-fin heat exchanger (PFHE) a well-known decision-making method which is called analytical hierarchy process (AHP). Finally, AHP method was employed again to select the superior scenario for improving the gas cycle. According to the results, the best scenario was the scenario in which heat recirculation with PFHE was used in the absence of mass recirculation. In this scenario, thermal efficiency and NOx emission were improved 4.20 and 17.94%, respectively. The payback time of the investment of the modification was also about 62 days. Moreover, due to the shortage of power in the case of mass recirculation, this scenario was found to be desirable when there is extra capacity in power generation, and the goal is reducing emissions as much as possible.

The operating condition for an experimental setup is usually determined using design of experiment method. However, it does not guarantee to achieve the best possible condition. Therefore, as the novelty, this study aims at using multi-objective optimization for this purpose, by which it could be sure that the best possible condition will be determined. In addition, energy, technical, environmental, and economic indicators have not been taken into account at the same time for finding the best condition before, whereas, as another novelty, they are all considered here. The multi-objective optimization is employed to determine the optimum operating temperature and pressure in an industrial process of toluene production as a solvent. Hildebrand solubility parameter, as well as economic benefit and consumed energy per unit mass of product, have been considered as the objective functions, while carbon dioxide emission has also been taken into account as the environmental function that is optimized to acquire a cleaner production line. According to the results, compared to the design of experiment method, the Hildebrand solubility parameter has been enhanced from 13.32 to 16.11 MPa0.5. Moreover, the benefit increased from 0.0488 to 0.0708 $ kg−1 while the energy production per mass of product had a 71.66% reduction. Acquiring a much cleaner production line to prepare the solvent is also guaranteed by employing the multi-objective optimization where the carbon dioxide emission has been reduced from 0.0793 to 0.0225 kg per unit mass of the prepared solvent. Decreasing both temperature and pressure from 534.15 to 381.65 K, and from 2.50 to 1.10 MPa, respectively, is another big advantage of the employed multi-objective optimization method, which leads to a safer condition.

In this study, a comprehensive time-dependent mathematical model for gas separation through the facilitated transport membranes (FTMs) is presented. The model results have been validated with independent CO2/N2 binary gas mixture experiments in DEA-impregnated PVA membranes. In the proposed model, non-equal diffusion coefficients of the carrier/complex and equilibrium constant for the chemical reaction kinetics between the carrier/permeant in the FTM have been considered. In addition, a method to compute the diffusion coefficients, which depend on the concentration of each component in the FTM, is presented. Moreover, effect of carrier concentration, feed partial pressure, kinetics of reversible chemical reactions and membrane performances depending on operating condition have been analyzed. Owing to accurate calculation of physical–chemical parameter involved, this model is much more executive comparing to previous works. In addition, the real condition of the reaction kinetics and influencing of diffusion parameters of the components in FTMs, have been investigated. The predicted selectivity and permeability revealed good conformity with experimental data; with standard deviation (SD) 8.57% and 12.87%, respectively. In conclusion, this model with significant validity would be predictive in cases for the entire range of diffusion-limit to a chemical-limit regime where the experimental data, geometry condition, physical–chemical property of parameters is not available.

Highlighting enhanced properties of polymers provided by dual-curing, self-healing coatings have been prepared via Diels-Alder and urethane formation reactions. These two orthogonal reactions were performed by functionalization of hydroxyl-terminated polybutadiene with furan dangling groups through thiol-ene reaction. In other words, the presence of the furan groups along with the terminal hydroxyl groups of HTPB made it possible to undergo in both urethane formation and Diels-Alder cycloaddition reactions, simultaneously. Remarking the effect of the Diels-Alder reaction on the self-healing ability of the samples, the proper bismaleimide compound has been selected by the DSC test. Moreover, a novel tetrafuran compound has been synthesized as crosslinking agent to improve the mechanical strength of the prepared coating and their self-healing properties. Evaluating the microscopic and macroscopic scales showed that the prepared coatings exhibited good healing properties as well as their mechanical properties. The microscopic imaging confirmed that the created scratches vanished after the healing process in all samples. Furthermore, the healed samples were displayed at least 50 % of their initial strength in the tensile test. Additionally, the results revealed that the coatings mechanical strength was reinforced from 1.34 to 2.30 MPa by introducing tetrafuran crosslinking agent in their matrix.

An extended approach to determine Hildebrand solubility parameter (HISP) of pure 1-alkanols by precise calculation of the isothermal compressibility coefficient and heat capacities is proposed. The approach is introduced during its implementation for four pure polar 1-alkanols, namely 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol. Having described the approach, the prediction ability of that is compared with the previous methods for calculation of the properties. Comparisons show that for all the three mentioned properties, the proposed approach provides significantly better predictions. The mean absolute error for prediction of the isothermal compressibility coefficient, isobaric heat capacity, and HISP by the proposed approach are 1.77, 1.32, and 0.17% (for 1-heptanol), 1.54, 1.11, and 0.18% (for 1-octanol), 2.90, 0.97, and 0.28% (for 1-nonanol), and 1.39, 1.61, and 0.39% (for 1-decanol), respectively. In addition to checking the accuracy of the proposed approach, to investigate the impacts of temperature and pressure as two key parameters on HISP of 1-alkanols, sensitivity analyses are conducted. The results of sensitivity analyses show that same as the non-polar substances, in the case of polar compounds, increase in pressure leads to an increase in HISP. Furthermore, when temperature does not change, HISP approaches a constant value at high pressures. Moreover, the relationship between temperature and HISP is linear.

In this research, the cross-linking of diethanolamine (DEA) impregnated poly(vinyl alcohol) (PVA) on polytetrafluoroethylene (PTFE) by glutaraldehyde (GA) with different blend compositions (GA/PVA: 0.5, 1, 3, 5, 7 ratio%) was performed in the absence of an acid catalyst and organic solvents in order to avoid any interference in CO2 facilitation reaction with DEA. The fabricated membranes were characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Furthermore, the effects of cross-linking agent content, feed pressure and composition as well as stability on CO2/CH4 transport properties were investigated in both pure and mixed gas experiments. The cross-linked membranes showed reasonable CO2/CH4 permselectivities in comparison with uncross-linked membranes. The best-yield CO2-selective membranes (DEA-PVA/GA(1 wt%)/PTFE) represented the best CO2/CH4 selectivity of 91.13 and 665 for pure and mixed gas experiments, respectively.

In this article, permeation models for nanocomposite polymeric membranes (NCPMs) filled with nonporous particles are discussed and two new models for prediction of effective permeability of NCPMs are proposed. To derive these models, the presence of interfacial layer at the surface of the nanofiller particles as well as the impact of two important phenomena namely creating void volumes and increasing free volume at the interface layer are taken into account. The capability of the models for prediction of reliable results is checked against available experimental data on permeability of NCPMs and is also compared with other presented models for such membranes. The new proposed models show profound superiority over the well known models such as “Bruggeman model in limit” which offers fairly good prediction for NCPMs.

In this study the gas separation performance of polyimide/polysulfone (PI/PSF) mixed matrix membranes filled with zeolite ZSM-5 particles is investigated. The membranes are prepared by solution-casting method and utilized to determine the permeation rates of N2, O2, CO2 and CH4 through pure polymers as well as composite membranes. The membranes are characterized by SEM, TGA and FTIR. The effects of polymers ratio and weight fraction of zeolite on permeation and selectivity of the gases are discussed. Polymers ratio in the mixed matrix have assumed values of 100% PSF, 70/30 (PSF/PI), 50/50, 30/70 and 100% PI while ZSM-5 loadings are varied between 0 and 20 wt.%. SEM results showed that fabricated membranes have homogeneous structure. With pure polyimide membrane, O2 permeability increased from 0.69 Barrer for membrane without zeolite up to 0.73 and 0.89 Barrer for membranes with 10% and 20% zeolite, respectively. Within blended matrices, the minimum permeability (maximum selectivity) and the most homogeneous matrix structure were related to the matrix with 50/50 weight percent of two polymers.

In this study, the effect of TiO2 nanoparticles addition on mixed matrix membranes (MMMs) based on Matrimd5218 prepared by using solution-casting method has been investigated. The morphology of MMM was evaluated by Scanning Electron Microscopy (SEM). TiO2 nanoparticles distribution in matrimid matrix and top surface of membrane films was observed by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), respectively. It was found that at low particle loadings (less than 15%) nanoparticles were mainly dispersed individually forming nanoscale aggregates. However, at high volume fractions (more than 20%) the size of aggregates increases and micro-scale aggregates form. The permeability of N2, CH4, O2, CO2 and He have been measured in order to determine the effect of TiO2 on gas separation performance of Matrimid5218. The results demonstrated that inclusion of TiO2 increases the gas permeability of MMMs possibly due to chain packing disruption, void formation at polymer–nanoparticle interface as well as within nanoparticle aggregates. For example, in MMMs containing 15 vol.% TiO2, the permeability of N2, CH4 and CO2 increased up to 2.76, 3.3 and 1.86 times higher than pure matrimid respectively. Diffusivity coefficients of larger molecules obtained by time-lag method show that permeability enhancement is mainly affected by diffusivity increment. Finally, the results reveal that use of TiO2 nanoparticles improves membrane performance in CO2/CH4 separation and presents a trade-off line with similar slope compare to Robeson upper insertion bound.