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Recent advances in renewable energy research have suggested the fuel cell as a promising future energy source. Compared to the conventional power generation process, which has multiple-step conversion, a fuel cell is a single-step conversion process and produces power and sometimes heat. The efficiency of the individual existing conventional system is increased by integrating with fuel cells. The purpose of hybridization is to fulfill the demand and supply of power and heat. This paper starts with the historical development of fuel cell proceed with different categorize of hybrid systems. Discuss the possibilities of integration of existing fuel cell with other existing technologies such as SOFC-PEMFC, FC-CHP, FC-GT-ST, FC-Hybrid Vehicle, FC-PV/Battery. Numerical modeling can be done for each hybrid system considering mass balance, energy-exergy balance. At the end of the paper a discussion on the technical, economical, and commercial challenges and their solutions with future possibilities is presented. [Display omitted] • Study the integration potential of fuel cell with other power generating systems. • Fuel-cell hybrid configurations are analyzed. • Modelling aspect of various fuel cell hybrid configurations were summarized. • Fuel cell behavior with power and heat generation is presented. [ABSTRACT FROM AUTHOR]

Industrial boilers are significant equipment in industrial operations used to provide steam or heat for production. More than 80% of fire-tube boilers use heavy oil in small and middle industries in Taiwan. Due to biodiesel as a sustainable fuel, the objective of this study is to measure experimentally and evaluated energy and exergy analysis of the fire-tube boiler using biodiesel (BD), undistilled biodiesel (UB), low sulfur oil (LSO), and ultra-low sulfur diesel (ULSD), and the various mixing ratios of undistilled biodiesel and low sulfur oil (UB90, UB70, and UB50) to reduce emissions from fire-tube boilers. Results from BD and UB are comparable, and UB exhibited a high NOx reduction rate of 68.9% and a high SO2 reduction rate of 99.5% compared to LSO. The boiler that employed UB decreased CO2 emissions, NOx, and SO2 emissions. NOx emission increases with increasing LSO content. The boiler’s maximum energy efficiency when using BD is 86.6%, and the overall exergy efficiency is 44.8%. The boiler with UB70 had the lowest energy efficiency of 73.5% and the lowest exergy efficiency of 38.7% because of the increased heat loss. The Benefits of this study are not only for boiler applications but also for government policy references.

Solar drying represents an attractive way to implement an efficient and green development strategy. The viability of open sorption thermal energy storage (OSTES) can compensate for the inherent shortcomings of intermittency and instability of solar energy for ensuring the continuity of the drying process. Nevertheless, the existing solar-powered OSTES technologies only allow a batch mode while being severely restricted by sunlight's availability, thereby heavily limiting the flexibility in managing OSTES on demand. Herein, a novel proof-of-concept that a standalone solar dryer integrated with a reversible solid-gas OSTES unit is presented. Using in situ electrothermal heating (in situ ETH) could rapidly release adsorbed water of activated carbon fibers (ACFs) in an energy-efficient manner to achieve a charging process with faster kinetics. Applying electrical power by a photovoltaic (PV) module, particularly during sunlight-absent or insufficient time, allowed multiple OSTES cycles to proceed. Moreover, ACFs cylindrical cartridges can be flexibly interconnected in either series or parallel, forming universal assemblies with well-controlled in situ ETH capacity. The mass storage density of ACFs with a water sorption capacity of 570 mg/g is 0.24 kW·h·kg-1. The desorption efficiencies of ACFs are higher than 90%, corresponding to 0.057 kW·h maximum energy consumption. The resulting prototype can diminish the fluctuation of air humidity along the night and provide a relatively steady and lower air humidity for the drying chamber. The energy-exergy and environment analysis of the drying section for both setups are estimated, respectively. [ABSTRACT FROM AUTHOR]

This paper contributes a novel sustainability index and modified exergy indicators for conventional gas turbines and solid oxide fuel cell integrated gas turbine (SOFC-GT) hybrid power cycles. In this work, an intercooled gas turbine (Ic-GT) cycle is considered as a base cycle, which gives an additive advantage in lowering the power required for the compressor. Moreover, on SOFC integration with Ic-GT, the qualitative and quantitative performance are examined. Numerical modeling is done using MATLAB and an exclusive comparison has been made based on energy-exergy and sustainability analysis for the system and its components. On comparing the first law efficiency at turbine inlet temperature, TIT 1250K and rp = 18 for Ic-GT, intercooled recuperated gas turbine (Ic-RGT), and Ic–SOFC–RGT, it is 25.82%, 36.04%, and 64.78%, respectively. Similarly, second law efficiency is 11.43%, 22.33%, and 61.11% and the overall sustainability index is 1.12, 1.28, and 2.57 for Ic-GT, Ic-RGT, and Ic–SOFC–RGT, respectively. Nine other modified exergy-based parameters are used to identify the role of fuel and product exergy and then compare the most affected component in three configurations. [Display omitted] • Gas turbine exhaust waste heat has been examined to power fuel cell. • Two typical intercooled gas turbines and a fuel-cell hybrid system are compared. • Energy efficiency, exergy efficiency, sustainability index are compared. • Configurations are compared using nine modified exergetic performance indicators. [ABSTRACT FROM AUTHOR]

Decreasing carbon emissions is possible with the usage of renewable energy sources. Therefore, the usage of renewable energy has increased in the last decade. Due to the fact that the drying process of agricultural products consumes a significant amount of energy, fossil fuel consumption can be reduced by using the solar dryer. In this study, two novel solar drying systems were designed and tested for alfalfa drying. Experiments were carried out in two different drying systems double‐pass solar air collector (DPSAC) and photovoltaic thermal solar air collector (PVT). In order to increase the heat transfer surface area, unlike the literature, a drying chamber consisting of two intertwined cylinders was designed and manufactured. The aims of this study are to bring the drying kinetics of alfalfa and the performance, energy, and exergy analysis of the designed system to the literature. The effective moisture diffusivity values were found to be in the range of 9.13 × 10−14 to 1.06 × 10−9 and the value for the highest drying rate was determined as 2.53 × 10−2gwater/gdrymatter.min. The highest thermal efficiency was obtained from DPSAC experiment as 73.7%, while the highest COP value was obtained from the PVT experiment as 12.5. The DPSAC dryer has shown the best performance in drying the alfalfa. The outcomes of the present study demonstrate that the use of DPSAC dryer is suitable when only heat energy is required for the drying system and the use of PVT when both heat and electrical energy are required. It is recommended that these systems can be used together in off‐grid agricultural areas. Practical applications: Alfalfa (Medicago sativa L.), a type of forage crop, is a delicious, high‐energy, and protein food source for dairy cattle. By drying the alfalfa with high nutritional value in a quality method, several beneficial minerals and vitamins are preserved. The drying process is used since ancient times for the protection of the food material and for storage without degradation. Alfalfa is dried in two new solar‐powered sustainable dryers making an important contribution to reducing carbon emissions as well as providing cleaner and more reliable drying methods compared to the conventional solar drying method. This study presents an alternative for the drying process with high energy efficiency for food drying processes, according to the necessity of using both heat and electrical energy. In addition, sustainable solar dryers in this study can be used for drying agricultural products, textile, industry and dewatering municipal waste. [ABSTRACT FROM AUTHOR]

• Novel combinations (PCM, PM, MWCNT-water) tested in PVT-HAWSC system. • The exergy, thermal, and electrical efficiencies of traditional and modified PVT-HAWSC systems are assessed. • PCM, PM, and MWCNT-water nanofluid integration boosts efficiency by 16.49%, 56.25%, and 93.64%, respectively. • Modified PVT-HAWSC system: LCOE of 0.043 $/kWh, 4.36-year payback, 36.55 tons CO₂ mitigation, and $529.98 carbon credits. • Modified PVT-HAWSC: 93.64% overall efficiency, 14.32% exergy efficiency, outperforming traditional system's 79% and 14%. This study presents a novel and low-complexity cooling system designed to enhance the performance of Photovoltaic Thermal (PVT) systems integrated with a Hybrid Air-Water Solar Collector (HAWSC), termed traditional PVT-HAWSC systems. The research addresses the limitations of these systems, such as low heat transfer fluid outlet temperature, thermal exergy, thermal and electrical efficiencies, and thermal power. This is achieved by incorporating phase change material (PCM), porous media (PM), and multi-walled carbon nanotubes (MWCNT)-water nanofluid into the traditional PVT-HAWSC system, resulting in a modified PVT-HAWSC system. The modified system features a double-pass single-duct air solar collector with steel wool-PM and a sheet-tube water thermal collector integrated with paraffin wax-PCM. Experimental investigations were conducted under varying flow rates of air, water, and nanofluid. The performance analysis included exergy, energy, thermal, and electrical assessments. Results demonstrated that fluid type and flow rate significantly impact performance. The modified system with nanofluid reduced the PV panel surface temperature by 28 °C, compared to 22 °C without nanofluid. Additionally, the average daily improvements in overall efficiency, total thermal efficiency, and electrical efficiency were 16.49 %, 56.25 %, and 93.64 % for the modified system, compared to 12.80 %, 43.16 %, and 79.90 % for the traditional system. Total thermal energy gained and average daily exergy efficiency were 302.72 W and 14.32 % for the modified system, compared to 235.4 W and 14 % for the traditional system. The modified PVT-HAWSC system achieved lower levelized cost of energy (LCOE) of 0.043 $/kWh, a 4.36-year payback, 36.55 tons of CO 2 mitigation, and $529.98 in carbon credits. [ABSTRACT FROM AUTHOR]

Energy is a determining factor for the global economy blossom. Nowadays, near 80% of the entire energy obtained from fossil fuel is principally applied for transportation area. Exhaustion of fossil fuel sources and greenhouse gases discharge inspire to the search of alternative fuels such as biodiesel. Due to the similar fuel attributes, biodiesel can be regarded as a replacement for diesel. In this study, it is aimed to produce biodiesel blends using Corn oil by employing the Transesterification method. Energy and exergy analyses for pure diesel and Corn biodiesel fuels were conducted operating a direct injection and four-cylinder in-line diesel engine with 3970 c.c. At 50%, and 100% engine load for the speed of 1700 and 2400 rpm. Brake-specific fuel consumption, Energy parameters (Input energy, Brake thermal efficiency of the engine, Combustion efficiency, and Energy losses), and exergy parameters (Exergy destruction and exergy efficiency) were assessed. It was found that by increases in brake thermal efficiency, the brake-specific fuel consumption lowers. At 1700 rpm and 100% load, B30 Corn biodiesel blend has the lowest brake-specific fuel consumption and has the best efficiency. At 2400 rpm, B30 Corn biodiesel blend presents the lowest fuel consumption and the highest efficiency. In the case of exergy analyses, B10 Corn biodiesel shows the highest exergy efficiency in both engine speeds. And the Corn biodiesel blends present the lowest exergy destruction in all engine states. [ABSTRACT FROM AUTHOR]

Energy is a determining factor for the global economy blossom. Nowadays, near 80% of the entire energy obtained from fossil fuel is principally applied for transportation area. Exhaustion of fossil fuel sources and greenhouse gases discharge inspire to the search of alternative fuels such as biodiesel. Due to the similar fuel attributes, biodiesel can be regarded as a replacement for diesel. In this study, it is aimed at producing four different biodiesel blends using sunflower oil, corn oil, canola oil, and restaurant waste oil by employing the Transesterification method. Energy and exergy analyses for pure diesel and four extracted biodiesel fuels were conducted operating a direct injection and four-cylinder in-line diesel engine with 3970 c.c. At 50%, and 100% engine load for the speed of 1700 and 2400 rpm. Brake specific fuel consumption, Energy parameters (Input energy, Brake thermal efficiency of the engine, Combustion efficiency, and Energy losses), and exergy parameters (Exergy destruction and exergy efficiency) were assessed. It was found that by increases in brake thermal efficiency, the brake-specific fuel consumption lowers. At 1700 rpm, B20 canola biodiesel blend has the lowest brake-specific fuel consumption and has the best efficiency. At 2400 rpm, B10 canola biodiesel blend presents the lowest fuel consumption and the highest efficiency. In the case of exergy analyses, B10 canola biodiesel shows the highest exergy efficiency in both engine speeds. And the canola biodiesel blends present the lowest exergy destruction in all engine states. [ABSTRACT FROM AUTHOR]

Summary: In this study, the first time in the literature, natural zeolite has been employed for photovoltaic thermal (PVT) and experimentally tested as a thermal energy storage material. The main aim of the paper is to introduce natural zeolite as a heat storage material for PVT systems. The PVT systems integrated with phase change materials and natural zeolite were designed, the components of the system were explained, the thermodynamical modelling including the first and second laws was presented, the system performances were evaluated, performance parameters were investigated, energy and exergy efficiencies were determined, and economical analyses of each system were performed. Besides, all results were compared with a conventional PVT system. The average overall energy efficiency values for PVT experiments were 33% for paraffin, 37% for stearic acid, 40% for zeolite, and 32% for conventional PVT systems. The payback period of the PVT system with paraffin, zeolite, stearic acid, and conventional PVT was calculated as 10, 8, 9, and 9 years, respectively. The results show that the natural zeolite is a material with significant potential to be used for heat management in PVT for any meteorological condition. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this study is to define and assess a new, renewable and sustainable energy supply system for islands and remote area where ocean thermal energy conversion (OTEC)/photovoltaic with hydrogen storage system is proposed. Components of this system are a turbine, generator, evaporator, condenser, pumps, photovoltaic panels, electrolyzer, hydrogen tanks, fuel cell and converter. To evaluate the proposed hybrid system, energy, exergy and economic analysis are employed. For OTEC, an optimization algorithm is applied to find the optimum working fluid (R134A, R407C, R410A, R717, R404A, and R423A), evaporation and condensation temperatures, and cold and warm seawater temperature differences between the inlet and outlet of evaporator/condenser. The results demonstrate that the maximum specific power of OTEC was achieved to be 0.3622 kW/m2 for R717 and 0.3294 kW/m2 for R423A working fluids. The overall energy efficiency for the hybrid renewable energy system was obtained 3.318%. The maximum energy loss was occurred by the turbine. The exergy efficiency of the hybrid system was obtained 18.35% and the payback period of the proposed system was obtained around 8 years. The unit electricity cost for the system was achieved as 0.168 $/kWh which is valuable compared to 0.28 $/kWh of the previous system. Highlights • A hybrid OTEC/photovoltaic system with hydrogen storage system is presented. • Energy, exergy and economic analyses are carried out to assess the proposed system. • The energy efficiency for the proposed system was obtained as 3.318%. • The exergy efficiency of the hybrid system was achieved as 18.35. • The payback period of the hybrid renewable energy system was found to be 8 years. [ABSTRACT FROM AUTHOR]

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The present work includes the production of six blends of biodiesel using waste cooking oil/mustard oil with methanol (99% pure) having NaOH/KOH (91% pure) as the catalysts. The kinematic viscosity, density, calorific value, flash point, cloud point, pour point, and cetane number of prepared bio-fuels were determined. The comparative energy-exergy analyses for six biodiesel fuels were conducted using a 4 inline-4stroke diesel engine with 2392 cc at 0%, 25%, 50%, and 100% load for constant/varying speed. The break-power (BP), heat taken by cooling water (Q w ), heat taken away by exhaust gases (Q ex ), and unaccountable losses were evaluated. It was found that the tested biodiesels offer competitive energetic performance to the diesel. The exergetic performance parameters followed similar trends with the corresponding energetic ones, but with increased brake specific fuel consumption and reduced exhaust emission due to higher oxygen content in biodiesel fuel. The results of analysis of variance clearly reflect that the B.P. is influenced most by the load, followed by the type of oil and speed has the least effect. It was also found that the biodiesels are having considerably lower CO emission than diesel. NOx emissions were least at higher load in diesel followed by waste cooking oils. Soot emissions were alike for diesel, waste cooking oils, and mustered oils at low load, but at higher load diesel has an exponential increment in soot emissions. [ABSTRACT FROM AUTHOR]

In order to investigate the characteristics of a heat pipe heat exchanger (HPHE) used for recovering the waste heat in a slag cooling process in steel industry, a waste heat recovery experimental system has been designed and established. Main parameters representing the HPHE are investigated experimentally and theoretically, the optimum operation conditions are determined by integrating the first and the second law of thermodynamics. The results indicate that the heat transfer ratio and heat transfer coefficient increase with waste water mass flow rates increasing at constant cold water mass flow rate. As the waste water mass flow rate varies between 0.8 and 1.9 m 3 /h, exergy destruction rate, exergy efficiency and effectiveness of the HPHE have the values from 0.277 to 0.510 kW; from 66.1% to 42.9% and from 0.085 to 0.192, respectively. The optimum waste water and cold water mass flow rate are deduced as 1.40 and 2.90 m 3 /h, respectively. In addition, the effect of on-line cleaning device on the heat transfer and fouling cleaning has been verified by experiments in this study. It is concluded that the heat transfer performance has been significantly improved after using the on-line cleaning device. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the significant effect of ammonia-water dilution pressure and density on the thermodynamic performance of ammonia-water combined cycle through energy and exergy destruction, enthalpy temperature, yields, and flow velocity. The energyexergy analysis is conducted on the ammonia water combined cycle and the Rankine cycle, respectively. Engineering Equation Solver (EES) software is utilized for performing such detailed analyses. Values and ratios regarding heat drop and exergy loss is presented in separate tables for different equipment. The results obtained by the energy-exergy analysis indicate that net power increases with the increasing ammonia-water dilution pressure in the boiler. This trend continues until pressure range reach in [169.3 - 180] bar and after that, it starts to decrease. In addition, the increasing of ammonia-water dilution pressure leads to reduction of boiler both exergy and total exergy destructions, it also results in an increment in the exergy performance coefficient (EPC). Moreover, it is also noticed that the combined cycle system improves its efficiency by about 5.81% compared with gas turbines. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate geothermal heat pump aided district heating for a town center with a population of nearly 25,000, from the exergy and economic points of view. By this way, different working fluids in a number of 12 were investigated to find the optimum solution of district heating system coupled with a geothermal heat pump system in which the geothermal resources of Simav region were directly used in a shell and tube type heat exchanger. In this aim, different system parameters such as temperature and pressure were investigated using energy and exergy analysis taking 4686 designs into consideration. The obtained results from these analysis then were evaluated from the economic aspects. For the best solution, the most economic geothermal heat pump system for district heating was revealed handling Life Cycle Cost ( LCC ) concept coupled with Net Present Value ( NPV ) analysis. It was found that it has been possible to heat the residences in a number between 7929 and 46,098 with NPV values changing between −1192.81 and 23.20 million US$. As a result, the number of 13,776 residences could be heated by using this proposed system. So, the pre-feasibility study shows that the usage of this proposed system would be an attractive investment for Simav region. [ABSTRACT FROM AUTHOR]

In the present study, a thermodynamic analysis of a cogeneration system in a pulp and paper industry under different operating modes i.e., singular and hybrid with a variable ambient temperature is conducted according to actual operating data. For singular operating mode, the power boiler is only employed using natural gas while for hybrid operating mode, the power boiler with the recovery boiler is employed using natural gas and black liquor as main fuels, respectively. The results show that for hybrid operating mode in comparison with the singular one, the thermal efficiency of turbine and condenser is enhanced by 1.36 and 7.7%, respectively while it is reduced by 2.8% for the power boiler. In addition, the overall thermal efficiency under singular and hybrid operating modes is 87.4 and 53.7%, respectively. For hybrid operating mode, the exergy destruction of power boiler decreases by almost 10% compared with that for the singular operating mode. Also, at hybrid operating mode, the soda is recovered with a mass flow rate of 33 tons/hour that is required for the cooking process in the chemical pulp section and additionally the consumption of natural gas in the power boiler is reduced by 11.8%. [ABSTRACT FROM AUTHOR]

The parametric analysis of a multi-effect-evaporation (MEE) desalination system combined with a thermal-vapour-compression (TVC) process activated by a gaseous stream of specified flowrate and temperature was performed based on the principles of classical (1st and 2nd laws) and finite-size thermodynamics. The MEE subsystem was treated as a black box and therefore the results are valid for any combination of physical characteristics and internal operational conditions of this subsystem. They show the effects of four design variables (the motive fluid pressure and the compression ratio of the ejector, the condenser temperature pinch and the ratio of rejected to supplied seawater) on significant operating quantities and performance indicators such as: energy supplied by the heat source; motive fluid flowrate; flowrates of the supplied seawater and produced potable water; specific heat consumption; thermal conductance of the vapour generator and the condenser; exergy destruction by the MEE, the ejector and the vapour generator. Based on the obtained results recommendations are formulated for the optimal choice of values for the four design variables. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a novel Concentrating Photovoltaic Combined System (CPVCS) based on the spectral decomposing approach is introduced, modeled, tested experimentally and evaluated thermodynamically and economically. In this study, energy and exergy analyses of the system have been evaluated, economical analysis has been performed and the experimental results have been compared to data obtained by the control system. As a result, energy efficiencies of concentrator, vacuum tube and overall CPVCS have been determined to be 15.35%; 49.86%; and 7.3% respectively. Similarly the second law (exergy) efficiencies of concentrator, vacuum tube and overall CPVCS are 12.06%; 2.0%; and 1.16% respectively. The cost of energy production has been stated as 6.37$/W and it is predicted that this value could be decreased by improving the system performance. [Copyright &y& Elsevier]

Abstract: The present work presents a thermodynamic performance analysis of a solar dryer with an evacuated-tube collector. Drying experiments for apples, carrots and apricots were conducted, after a preliminary stage of the investigation which included measurements for the determination of the collector efficiency. These results showed that the warm outlet air of the collector attains temperature levels suitable for drying of agricultural products without the need of preheating. Thus, the present collector was used as the heat source for a drying chamber in the frame of the development of a novel, convective, indirect solar dryer; given the fact that in the literature there are only a few studies about this type of collectors in conjunction with solar drying applications. Thin-layer drying models were fitted to the experimental drying curves, including the recent model of Diamante et al. which showed good correlation coefficients for all the tested products. Drying parameters such as moisture ratio and drying rates were calculated. Furthermore, an energetic/exergetic analysis of the dryer was also conducted and performance coefficients such as pick-up and exergy efficiencies, energy utilization ratio, exergy losses were determined for several configurations such as single and double-trays and several drying air velocities. On the other hand, an optimal collector surface area study was conducted, based on laws for minimum entropy generation. Design parameters such as optimum collector area were determined based on the minimum entropy generation number. The mass flow number, along with the maximum collector and fluid exit temperatures were studied in relation to the minimum entropy generation. The energy/exergy analysis proposed, provides a useful tool for the evaluation of this type of collectors regarding their effectiveness as part of a solar drying system. Moreover, the results of the present study showed that the proposed solar dryer has a capacity for drying larger quantities of the products than those considered (in the frame of the experimental study) given the high efficiency of the collector. In general, the proposed system provides an interesting option for the penetration of this type of collectors in large-scale applications in the agricultural and industrial sector. [Copyright &y& Elsevier]

Abstract: Textile industry plays an important role economically in Turkey. A great amount of hot waste liquids and gases are let out in many textile processes. These waste liquids and gases have crucial energy saving potential, especially for dyeing process. It could be possible to provide energy saving by employing a waste heat recovery system (WHRS). The optimum operation conditions were assessed by integrating the first and the second law of thermodynamics for a counter flow PHE employed for a dyeing process in textile industry. The WHRS has been established by a well-known blanket manufactory located in Usak Organized Industrial Zone (UOIZ), Turkey has been evaluated. While the waste water mass flow rate varies between 8 and 12m3/h, exergy destruction rate, exergy efficiency and effectiveness of the PHE have the values from 5.55 to 13.68kW; from 53.6% to 67.2% and from 0.996 to 0.810, respectively. Optimum waste water and cold water mass flow rate was found as 10.00 and 7.00m3/h, respectively. While the cold water mass flow rate varies between 5 and 9m3/h, exergy destruction rate, exergy efficiency and effectiveness of the PHE have the values from 8.05 to 10.89kW; from %56.3% to %63.9% and from 0.868 to 0.991, respectively. While the waste water inlet temperatures vary between 52.4 and 59.5°C, exergy destruction rate, exergy efficiency and effectiveness of the PHE have the values from 5.40 to 9.46kW; from 68.7% to 61.6% and from 0.969 to 0.924, respectively at optimum mass flow rates. The present study has a great potential to serve applications of WHRS for textile application especially dyeing process. It is expected that the approach presented here would be beneficial to everyone involved in the design and performance evaluation of WHRS with PHE in many industrial sectors. It is clear that employing PHEs operating optimum conditions contribute energy savings, decrease energy cost, improve environmental impacts and shorten process period and supply economical benefits for textile industry as well as the other industrial sectors. [Copyright &y& Elsevier]

Abstract In this paper, the energy and exergy analysis results of sugar production processes were presented by using operational system data from the Kayseri sugar plant, Turkey. All sugar production processes were thought as a steady state open thermodynamics system and employed the energy and exergy analyses, based on the first and second laws of thermodynamics. The best values of the energy and exergy efficiencies were obtained as 95·1% for the juice production process and 74·3% for the juice concentration process respectively. Moreover, the location of the energy degradation and the irreversibility were determined during the whole sugar production processes. Consequently, it has been pointed out that the energy and exergy efficiencies can be improved if the rates of the energy degradation and irreversibility in the sugar production processes are reduced. [ABSTRACT FROM AUTHOR]

Solar energy is considered the most influential source for various sustainable applications and its utilization can effectively convert brackish water into freshwater. The present work explores a novel method of augmenting the water productivity of the desalination unit using sea-water as the feed water through integrating a parabolic trough collector (to preheat the water supplied to the still basin) and activated carbon pellet (a highly porous energy storage material) to improve the rates of evaporation and water production. Experimental results revealed that the full-day water yield was augmented by 50.21% for the modified desalination unit, as compared to the conventional unit. 24-Hours water yield of modified solar still was increased by 85.2% compared to the conventional unit, owing to the synergetic effect of the parabolic trough and porous carbon. However, the integration of the parabolic trough collector significantly reduced the energy and exergy efficiency of the modified unit. The economic analysis estimated that the cost of the produced clean water was 0.010 US $ per liter for the modified unit, with a payback period of 66 days. Moreover, it was found that the modified desalination unit configuration can reduce CO 2 emissions by 18.74 tons during its lifespan. • Wettability behavior of glass cover was found to be hydrophilic. • SEM image of activated carbon showed highly porous structure. • Utilization of parabolic collector and porous carbon augment yield of SS by 85.2% • Exergy and energy efficiency reduced with integration of parabolic trough collector • Water quality analysis shown excellent water condition after the desalination [ABSTRACT FROM AUTHOR]

In this paper, the potential of expander speed regulation for optimization of ORC system adaptability to off-design working conditions has been explored through experiments. According to the obtained results, it has been found that there existed two different optimal speeds: optimal power speed (r op), optimal efficiency speed (r oee /r ote) which could endow the ORC system with maximum output power or highest thermoelectric/exergy efficiency. For working conditions of t w = 70, 73, 80 °C, power of expander at r op has been increased by 199.1%, 137.4%, 6.5% compared with the power output at design speed (r ds). The thermoelectric efficiency at r ote was 11.1%, 27.7% higher than that at r op and r ds. To further investigate the influences of expander speed on the performance, energy and exergy analyses were conducted based on theoretical calculation and experiment results within the range of 400–1600 r/min. The results showed that actual exergy destruction of expander and working fluid pump was closely related to expander speed. Gaps between theoretical and actual exergy destruction rates proved that optimization of expander and working fluid pump would be more effective for the ORC system performance. • Expander speed regulation shows high potential for improving off-design performance. • Experiment-based exergy-energy analyses at different expander speeds are performed. • There is optimal power speed and efficiency speed for ORC system. • Prior attention should be paid to improve the WFP and expander. [ABSTRACT FROM AUTHOR]