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The increase in the feasibility of hydrogen-based generation makes it a promising addition to the realm of renewable energies that are being employed to address the issue of electric vehicle charging. This paper presents technical and an economical approach to evaluate a newer off-grid hybrid PV-hydrogen energy-based recharging station in the city of Jamshoro, Pakistan to meet the everyday charging needs of plug-in electric vehicles. The concept is designed and simulated by employing HOMER software. Hybrid PV-hydrogen and PV-hydrogen-battery are the two different scenarios that are carried out and compared based on their both technical as well as financial standpoints. The simulation results are evident that the hybrid PV- hydrogen-battery energy system has much more financial and economic benefits as compared with the PV-hydrogen energy system. Moreover, it is also seen that costs of energy from earlier from hybrid PV-hydrogen-battery is more appealing i.e. 0.358 $/kWh, from 0.412 $/kWh cost of energy from hybrid PV-hydrogen. The power produced by the hybrid PV- hydrogen - battery energy for the daily load demand of 1700 kWh /day, consists of two powers produced independently by the PV and fuel cells of 87.4 % and 12.6 %, respectively.

A distributed generation network could be a hybrid power system that includes wind–diesel power generation based on induction generators (IGs) and synchronous generators (SGs). The main advantage of these systems is the possibility of using renewable energy in their structures. The most important challenge is to design the voltage-control loop with the frequency-control loop to obtain optimal responses for voltage and frequency deviations. In this work, the voltage-control loop is designed by an automatic voltage regulator. A linear model of the hybrid system has also been developed with coordinated voltage and frequency control. Dynamic frequency response and voltage deviations are compared for different load disturbances and different reactive loads. The gains of the SG and the static volt-ampere reactive compensator (SVC) controllers in the IG terminal are calculated using the Black Widow Optimization (BWO) algorithm to insure low frequency and voltage deviations. The BWO optimization algorithm is one of the newest and most powerful optimization methods to have been introduced so far. The results showed that the BWO algorithm has a good speed in solving the proposed objective function. A 22% improvement in time adjustment was observed in the use of an optimal SVC. Also, an 18% improvement was observed in the transitory values.A distributed generation network could be a hybrid power system that includes wind–diesel power generation based on induction generators (IGs) and synchronous generators (SGs). In this work, the gains of the SG and the static volt-ampere reactive compensator (SVC) controllers in the IG terminal are calculated using the Black Widow Optimization (BWO) algorithm to insure low frequency and voltage deviations.

This paper presents reliability, availability, and maintainability (RAM) analysis framework for evaluating the performance of a circulation system of water (WCS) used in a coal-fired power plant (CFPP). The performance of WCS is evaluated using a reliability block diagram (RBD), fault tree analysis (FTA), and Markov birth–death probabilistic approach. In this work, the system under study consists of five subsystems connected in series and parallel configuration namely condensate extraction pump (CEP), low-pressure feed water heater (LPH), deaerator (DR), boiler feed pump (BFP), high-pressure feed water heater (HPH). The reliability block diagram (RBD) and fault tree approach (FTA) have been employed for the performance evaluation of WCS. The Markov probabilistic approach based simulation model is developed. The transition diagram of the proposed model represented several states with full working capacity, reduced capacity, and failed state. The ranking of critical equipment is decided on the basis of criticality level of equipment. The study results revealed that the boiler feed pump affects the system availability at most, while the failure of deaerator affects it least. The availability of the system is optimized using the particle swarm optimization method. The optimized availability parameter (TBF, TTR) based modified maintenance strategy is recommended to enhance the availability of the plant system. The optimized failure rate and repair rate parameters of the subsystem are used to suggest a suitable maintenance strategy for the water circulation system of the thermal power plant. The proposed RAM framework helps the decision-makers to plan the maintenance activity as per the criticality level of subsystems and allocate the resources accordingly.

The baking performance of fresh, non-fermented, pre-fermented and pre-rested doughs were investigated using different types of flours. Effect of protein content in wheat flour and effect of oat and barley supplementation on wheat dough and baked bread was evaluated. Effect of mixing speed, yeast concentration and two different proofing methods were also studied. Wheat flour with higher protein content gave a higher volume and specific volume. The substitution of wheat flour with increasing concentrations of oat and barley flour progressively decreased loaf and specific volume significantly. Prolonging the proofing time after thawing resulted in a good bread quality whereas high mixing speed did not affect the bread quality. The operating conditions for the proofing step were at 35 °C temperature and 80% relative humidity for 30 min. Higher concentration of baking yeast results in low quality crust in baked bread. Yeast concentration of 1.3% showed the best option for bread preparation, at which the bread moisture content was the highest. The results also showed that wheat flour with 13.3% protein content yielded higher volume than bread made from 10% protein content. The dough was stored at − 20 °C and the baking conditions were at 215 °C temperature for 25 min. Sensory studies did not yield significant variation in different bread preparations. The pre-rested frozen dough, gave the best baked bread compared to the pre-fermented and non-fermented breads.

The increasing utilization of non-renewable energy resources contributes to the rise in greenhouse gas emissions, leading to a growing focus on renewable resources as viable alternatives for energy production. Biomass, being a sustainable and feasible source, offers a promising solution for clean energy generation. Due to its cost-effectiveness, pyrolysis is appealing as it produces bio-oil, bio-char, and syngas. This study investigated bio-oil production using spent coffee grounds as the feedstock in a fluidized bed reactor, varying the reaction temperature and residence times. Different pyrolysis temperatures' effect on the bio-char and bio-oil yields and energy content were analyzed. The results show that higher temperatures lead to higher bio-oil yields, lower bio-char yields, and shorter residence times. The highest bio-oil yield and energy content can be produced at 500 °C. The bio-oil obtained from the spent coffee grounds has a density of 0.991 g/cm3, a viscosity of 52 cP, and a higher heating value of 41 MJ/kg. Therefore, the spent coffee grounds are a suitable feedstock for bio-oil production for sustainability.

•A novel solar-assisted HVAC in UAE was studied.•Energy recovery and passive techniques were investigated.•31.5% space-cooling load was reduced by passive methods.•A good agreement was obtained between the analytical model and the experimental results.•A maximum COP of 5 was achieved compared to 3.82 in conventional system.

The effect of adding different aggregates on thermal and mechanical properties of concrete is investigated. The materials used as aggregates are crushed rubber results from wasted tiers, recycled plastics, organic, and inorganic wastes. The mechanical and thermal properties of concert investigated are density, compressive strength, and thermal conductivity. Moreover, data of the drying rate of concrete with compressive strength are shown. The study shows a comparison between modified concrete and traditional one is shown. Results shown that rubberized concrete showed a drop in the compressive strength, thermal conductivity, and density. For example adding 10% of rubber aggregates the compressive strength dropped by 8 MPa for 7 days of drying and 10 MPa for 28 days of drying. The average reduction of thermal conductivity between the three mixes was 0.11W/m.K. The average decline in the concrete density between the three mixes was 122 kg/m3.

In this work, a theoretical model to analyse the performance characteristics of a MagnetoHydroDynamic (MHD) generator power plant is presented. The external irreversibilities as well as the internal irreversibilities are taken into account in the analysis. General expressions for the power and efficiency are obtained when the MHD generator is operating at constant velocity and constant Mach number conditions. It is shown that both conditions are identical in performance when the generator and compressor are running reversibly. For less than 100% generator electrical efficiency, the MHD generator produces less entropy generation when it is running at constant velocity than that of constant Mach number condition.

The maximum power output and the efficiency at that power of a combined heat engines are analysed by using Curzon and Ahlborn's finite-time analysis. The efficiency at the maximum power of the combined reversible and irreversible heat engines has been obtained. This work also shows that when the engines are internally irreversible, the combined cycle delivers less power and has lower efficiency than an endoreversible combined heat engines. An expression is derived to relate the maximum power output ratio (irreversible/endoreversible) to the corresponding cycle efficiency ratio. It is shown by that relation that the efficiency ratio is much higher than the power ratio and they become identical when the irreversible cycle is very close to the endoreversible one.

A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The thermoelectric generator is considered as a heat engine cycle process with internal irreversibilities. The efficiency of the thermoelectric generator is expressed in terms of two non-dimensional parameters which are to be optimized. A finite-time thermodynamic analysis is used to optimize the temperatures of the hot and cold junctions of the real thermoelectric generator. A comparison between ideal and real waste-heat thermoelectric generators is demonstrated.

In this article, the performance of regenerative power plants in terms of second law of thermodynamics is discussed. The performance of the cycle is improved with the addition of backward cascaded-type and open-type feedwater heaters. This improvement is obtained by the reduction in irreversible losses as the number of feedwater heaters increases. A conventional energy-balance approach is used to calculate the irreversible losses in the cycle. The irreversible losses of each component of the cycle is given in a dimensionless ratio and from that ratio one can easily see the fraction of the irreversible losses of each component with respect to the power output, which means the irreversible losses can be obtained directly from the power output. The boiler causes the maximum fraction of the total irreversible losses among the components of the cycle. These losses are reduced by introducing feedwater heaters into the cycle. The irreversibilities in the cycle are examined according to the effect of varying the total temperature rise across the feedwater heaters.

A thermodynamic analysis of a thermoelectric cooler is proposed. The coefficient of performance of the cooler is expressed in terms of two dimensionless parameters which are to be optimized. The thermoelectric cooler is considered as an irreversible Carnot-like reversed heat engine. The effect of the external irreversibilities on the coefficient of performance and cooling rate is investigated by the use of finite-time thermodynamic analysis. The coefficient of performance and cooling rate increase with an increase in the temperature ratio defined in the analysis.

•Heat and mass transfer in heat exchanger under partially wet-surface condition is focused.•Governing equations are derived by applying energy balance on repetitive fin two-dimensionally.•Increase in the percentage of fin wetness area leads to a decrease in efficiency.•Fin percentage of wetness plays a significant role in fin efficiency.