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This work focuses on the structure, working, and testing of a new mixed solar cooker using a linear Fresnel collector, evacuated tube and box‐type cooker. The low‐cost components used in the construction of this cooker can help it satisfy the needs of both urban and rural inhabitants who need steady cooking temperatures above 140°C. A family of five can prepare four meals using this modified solar cooker, which costs about $250. The designed solar cooker was tested by conducting no‐load and full‐load tests. For the no‐load test, the maximum temperature of the absorber plate and oil for the new mixed cooker was recorded as 160.26°C and 172.72°C, respectively. The absorber plate of the new mixed cooker and its oil both reached their highest temperatures during the full‐load test at 141.14°C and 157°C, respectively. The energy efficiency of the new cooker is 58.776%, while its exergy efficiency is 13%. The heat transfer coefficient increased to 100.16 W/m² °C. This cooker provides an additional time savings of 60 min. An improvement of 27.5% in the highest temperature reached was seen when the developed cooker's performance was compared with those reported in the literature. Additionally, the new cooker's heat‐storing capability enables up to 3 h of autonomy. The Levelized Cost of Cooking a Meal for the innovative mixed solar cooker is $0.034 per meal. [ABSTRACT FROM AUTHOR]

The distillation tower's reboiler is one of the largest energy consumers in petrochemical facilities, and reducing its energy consumption is a crucial issue. This study proposes two optimal methods, namely Direct Vapor Recompression (DVR) and External Vapor Recompression (EVR), to reduce the consumption of cold and hot utilities in a petrochemical deethanizer tower. The Pars petrochemical in Iran is taken as a case study, and the proposed methods are compared with the base case using energy, exergy, and economic approaches, simulated through Aspen HYSYS software in the steady-state design conditions. Exergy analysis reveals that the EVR and DVR methods reduce the exergy destruction of the deethanizer tower by about 70.06 % and 67.29 %, respectively, compared to the base case. Moreover, the EVR method allows for complete recycling of low-pressure vapor, reducing the total exergy destruction rate from 0.871 to 0.261 GJ/tethane. The feed separation cost for the base case, DVR, and EVR are estimated to be around 28 $/kgfeed, 21.57 $/kgfeed, and 21.14 $/kgfeed, respectively. The EVR method results in reduced utility and ethane separation cost rates from 5.153 to 3.274 $/tethane and 17.64 to 15.78 $/year. Overall, the findings suggest that both DVR and EVR methods are effective in reducing the energy consumption and costs associated with deethanizer tower operations. Moreover, real-time optimization techniques can be developed to monitor and adjust the deethanizer tower's operating parameters, such as feed flow rate, reboiler duty, and reflux ratio. [ABSTRACT FROM AUTHOR]

This paper suggests a novel framework to retrieve the squandered heat of the Naphtha Hydrotreating Unit of the petrochemical plants. In this idea, the distillation tower's output of the hydrotreating naphtha unit of the plant is employed as the working fluid to run an organic Rankine cycle with benzene. The procedure is evaluated comprehensively from energy, economic and exergetic point of view using Aspen Haysys software. An advanced case study, including sensitivity analysis, is provided for the Bouali petrochemical plant in Iran to realistically indicate the performance of the suggested configuration. The air cooler in the distillation unit of the aforementioned plant removes (squanders) about 3418 kW of energy, which an organic Rankine cycle can recover. Based on the findings, the exergetic and thermal efficiency of the suggested cycle is 82.53 % and 13.28 %, respectively, with a 1,3620kWh/day rate of energy production. According to the exergetic analysis, the ORC turbine has the highest exergy destruction rate of about 178.76 kW. Also, using the distillation tower squander heat as the heat source to the organic Rankine cycle leads to the least exergy destruction rate. Besides, the output exergy ratio of the whole integrated system to its input is 0.907. The suggested integrated system reduces the total energy consumption from 0.4 to 0.29 GJE/tonFeed with a total investment cost of 11.97 M$, in which the turbines have the highest portion of about 11.2 M$. Hence, the suggested plan's total income is around 31.94 M$/year. [ABSTRACT FROM AUTHOR]

Novel sustainable solar powered combined desalination and hot water system is investigated based on energy, exergy and economic performances experimentally. For the purpose, evacuated tube collector integrated serpentine based active desalination unit is fabricated to fulfil the potable water and hot water supply especially in hospitals, hill station buildings and remote locations. Experimental investigations are performed for various mass flow rates in serpentine at different basin water depth (0.03, 0.04 and 0.05 m) over nine typical days. Effect of solar insolation and atmosphere temperature on potable water yield and system energy and exergy efficiencies are analyzed under real weather conditions. Measurements reveal that, maximum daily potable water yield, energy efficiency, exergy efficiency and hot water temperature are obtained as 5.10 kg/m2·day, 42.39%, 4.45% and 67°C, respectively at 0.03 m water depth and lower mass flow rate. Additionally, potable water cost per litre (CPL) found minimum as 0.04073 $/L/m2 for 25 y of operating life of system. [ABSTRACT FROM AUTHOR]

The conversion of solar energy into thermal energy using a solar water heating system seems to be a viable technology. Nanofluids are a well-established method of increasing the solar water heater's heat output. Solar thermal collector receiver tube heat transfer enhancers and geometrical characteristics have been analyzed for their impact on energy and exergy efficiency. Assessments of energy and exergy can greatly improve the performance of solar collectors and reduce their irreversibility. This challenge aims to generate full document research on various solar thermal collectors' energy and exergy assessments. Various heat transfer enhancers and geometrical characteristics of the receiver tube of a solar thermal collector have been developed and evaluated for their effects on energy and exergy efficiency. This paper suggests a solar water heating system using zinc oxide-based nanofluid (SWHS-ZO-NF). Distilled water/zinc oxide nanofluids are employed in the recommended solar water heating systems strategy with parabolic trough solar collectors. It is necessary to apply a surfactant to keep the nanoparticles from settling. Although the addition of surfactant increased the nanoparticle's stability in the base fluid, it will harm the nanofluid's thermophysical properties. The system's exergy loss is reduced when the nanofluid's volume concentration increases. The experimental result of the suggested SWHS-ZO-NF improves the energy analysis and exergy analysis, viscosity and thermal conductivity, exergy loss and entropy generation, electrical power and electrical efficiency, and thermal power and thermal efficiency. [ABSTRACT FROM AUTHOR]

Efficient power generation systems are an essential way to reduce carbon emissions. To avoid the complex effects of high-pressure conditions on the solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems, while further improving energy efficiency. A SOFC-GT hybrid system based on the reverse Brayton cycle (RBC) is proposed, in which the SOFC operates at near atmospheric pressure conditions and GT expands below atmospheric pressure. Solar energy is integrated to further enhance system performance. Rigorous assessments of the novel system and the pressurized system are conducted utilizing energy, exergy and economic analysis. The sensitivity analysis of environmental parameters on the novel system's performance is performed. The results show that the novel system generates power and efficiency better than the conventional system when the GT compression ratio is 3 and 6, respectively. The power generation and exergy efficiency of the novel system at the design point is 60.47 % and 58.57 %, respectively. The largest exergy destruction occurred in the SOFC. The lowest exergy efficient components are the parabolic dish collector (PDC) and heat exchanger 2. The novel system is more cost-effective due to the higher lifetime of the SOFC, with the levelized cost of energy (LCOE) is 0.1418 $/kWh. • The reverse Brayton cycle is applied to solid oxide fuel cell and gas turbine hybrid system. • Solar energy is coupled to further improve system performance. • The comparison between the novel system and the conventional system is analyzed. • The influence of external environmental factors on the novel system is analyzed. [ABSTRACT FROM AUTHOR]

Summary: Metallic solder based PCMs possess higher thermal conductivities, larger storage masses and exhibit lower subcooling effects compared to their organic or inorganic counterparts. It is thus justified to investigate their potential usage for medium temperature applications. These solders are relatively expensive and can be combined with cheaper PCMs in cascaded storage systems which are more thermodynamically efficient compared to single PCM systems as reported recently. The aim of the research is thus to compare two packed bed storage systems during discharging cycles using eutectic solder (Sn63/Pb37), that is widely available worldwide. The single PCM system (40 capsules) consists of encapsulated spheres of eutectic solder, whereas the second cascaded system consists of encapsulated spheres of eutectic solder and erythritol in an equal storage ratio in the tank. For the cascaded system, the eutectic solder capsules are placed at the top and erythritol at the bottom of the storage tank (20 capsules at the top and 20 at the bottom). The effect of the discharging flow‐rates of 4 mL/s, 6 mL/s and 8 mL/s is investigated in relation to the temperature profiles, energy rates and exergy rates. Increasing the flow‐rate, increases heat transfer rate thus shortening the discharging time as well as increasing thermal profile reversals during discharging. The peak energy and exergy rates increase with the increase in the flow‐rate for the two storage systems. The single PCM system shows slightly higher average energy and exergy rates compared to the cascaded system possibly due to its higher thermal conductivity. The cascaded PCM system shows higher average stratification numbers at all the flow rates considered. The non‐cascaded system exhibited slightly higher exergy recovery efficiencies compared to the cascaded PCM system possibly due to its higher thermal conductivity at all flow‐rates considered. The effect of the initial discharging temperature is also investigated with a discharging flow‐rate of 6 mL/s after charging with set heater temperatures of 260°C, 280°C and 300°C, respectively. Comparable thermal profiles are seen for both systems for the three set temperatures; however, the single PCM system shows slightly higher storage temperatures. The single PCM shows slightly higher but comparable peak and average discharging energy rates compared to the cascaded system. The exergy rates for the two systems are also comparable. However, the cascaded system shows slightly higher exergy rate values for the lowest set temperature whereas the single PCM system shows slightly higher exergy rate values for the other two set temperatures. Energy and exergy rates are almost independent of the initial storage tank temperatures induced by different set charging temperatures. The average stratification number shows no correlation with set temperature for both storage systems. The cascaded system shows slightly higher average stratification numbers at different set temperatures. Exergy recovery efficiencies for different set heater temperatures are comparable for the two storage systems and vary only marginally with the increase in the set temperature. Overall, the effect of the flow‐rate is more pronounced than the effect of the set heater temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel thermal storage integrated evacuated tube heat pipe solar air heater. • Suitable for high temperature air heating applications. • A new common condenser heat pipe arrangement was introduced in the system. • High temperature air was obtained during off sunshine hours. • This new solar air heater is an efficient and environment friendly device. This study aims to present a novel thermal energy storage integrated evacuated tube heat pipe solar air heater suitable for high-temperature applications. A new heat pipe arrangement was introduced in this study by attaching all the evaporator tubes of heat pipes to a common condenser section. A thermal energy storage medium was kept in a chamber within the common condenser unit of the heat pipe to obtain uniform outlet air temperature from the system when there is fluctuation in solar radiation. Therminol 55 was used as the sensible heat storage medium in the system. The Performance evaluation of the system was conducted by varying four airflow rates 0.03 kg/s, 0.1 kg/s, 0.2 kg/s and 0.3 kg/s, respectively. 0.03 kg/s resulted in a maximum outlet air temperature of 128 °C and the system delivered more than 100 °C of hot air until 10 h of operation. The maximum thermal and exergy efficiency obtained during each airflow rate was 38%, 77%, 85%, 89%, and 5.01%, 5.21%, 5.34%, and 5.76% respectively. An average of 6200 kJ energy was collected by the present system during its operation. The total money saved per month during the operation of TS-ETHPSD was 445 INR. The Payback Period for the system is 69 months. The solar air heater can be considered as an environment-friendly device as it can save 73 kg/month of Co 2 from entering the atmosphere. [ABSTRACT FROM AUTHOR]

In this study, an assessment based on energy, exergy, economic, and environmental approaches on a double-pass (DP) solar air heater (SAH) having pin finned absorber at different air mass ratios up and down the absorber is investigated experimentally. Four air mass ratios are considered: (i) all the air mass flow passes up the absorber and returns to pass down the absorber (DP), (ii) 2/3 of the airflow passes up the absorber and returns to mix with the remainder of air to pass down the absorber (2/3 DP), (iii) the same as (ii) but 1/3 of the air passes up the absorber (1/3 DP), and (iv) all the air mass passes only down the absorber (single pass, SP). For all mass ratios, the performance of pin finned SAH (P_SAH) is compared with that of flat SAH (F_SAH). The results indicated that the air temperature rise and energy and exergy efficiencies of P_SAH are highly greater than those of F_SAH. The highest average thermal efficiency of F_SAH is 56.7% obtained at DP flow condition, whereas the highest value of P_SAH is 65.21% obtained at 2/3 DP with an increase of 17.6% compared with F_SAH. Also, P_SAH has higher average exergy efficiency of about 34.7% compared to F_SAH. Furthermore, P_SAH achieves energy payback time (EPBT) lower than that of F_SAH, while P_SAH has higher embodied energy. The findings indicated that F_SAH at SP airflow pattern has the maximum energy cost (0.0427 $/kWh), whereas P_SAH at 2/3 DP airflow pattern achieves the minimum energy cost (0.037 $/kWh). Finally, the proposed P_SAH system appears to be more viable from exergoeconomic and enviroeconomic approaches compared to F_SAH. [ABSTRACT FROM AUTHOR]

In this paper, a novel small-decentralized desalination device is presented for increasing the temperature difference between brackish water and glass cover, so as to enhance the solar still's freshwater productivity. This novel solar still device is based on installing a lens in front of the single slope solar still, and two lenses on still's both sides, and a reflector over the back side of the solar still. The main objective of such novel still is to concentrate sunrays at the still's bottom basin, through the refraction function of Fresnel lens. Furthermore, this novel still makes the reflector transferring its reflected sunrays to the solar still's basin. Experiments are conducted under the climate conditions in Hangzhou city, China, for testing the novel still's operational performance, and internal heat and mass transfer characteristics. Assessment of the novel still's feasibility is performed based on energy, exergy, exergoeconomic, and enviroeconomic methodologies, as well as energy payback time. Results show that the productivity of novel still is 32% higher than that of conventional still, and novel solar still enhances the average hourly energy efficiency by 97.73%, compared to conventional solar still. While, the corresponding value of hourly exergy efficiency is also enhanced by 43.713%. Due to the higher energy and exergy outputs of novel still throughout its lifetime, the novel solar still proposed in this study mitigates more CO 2 compared to the conventional still. Overall, incorporation three lenses and one reflector with the still is found promising in terms of freshwater yield, cost, and energy payback time compared to conventional one. Exergoeconomic and environmental parameters of the novel solar still are found more effective compared to the conventional one. • A novel solar still with lenses and reflector is developed and evaluated. • Using lenses and reflector increases still's productivity by about 32%. • Novel solar still enhances the average hourly energy efficiency by 97.73%. • Novel still mitigates more CO 2 compared to conventional one based on energy & exergy. • Novel solar still's enviroeconomic and exergoenvironmental are 324.317 $ and 22.148 $. [ABSTRACT FROM AUTHOR]

The performance of single slope solar still with an enhanced condenser at different saline water mediums in the basin is studied and assessed based on productivity, energy, exergy, economic, and enviroeconomic methodologies. Six solar still configurations are considered: conventional solar still (CSS); modified solar still (MSS) which is a still with heat sink condenser; MSS having an umbrella (MSS + U); MSS with forced-air cooling (MSS + FA); MSS with forced-water cooling (MSS + FW); and finally, MSS with forced-water cooling and contains sand in the basin (MSS + FW + SD). Experiments are conducted under hot and cold climate conditions of Sohag city, Egypt. The results indicate that the MSS + FW + SD has a maximum daily yield of 5.37 kg/m2 in summer and 2.74 kg/m2 in winter with an increase of 36% in summer and 26% in winter compared with CSS. It was found that the maximum increase of the energy and exergy efficiency compared with CSS is achieved in the case of MSS + FW + SD of 39% and 33%, respectively. Furthermore, the maximum and minimum cost of freshwater is achieved in cases of MSS + U and MSS + FW + SD, respectively. Finally, among all studied systems, MSS + FW + SD achieves the best performance based on the exergoeconomic approach. [ABSTRACT FROM AUTHOR]

• PV/T collector integrated with infrared convective dryer. • Air cooling PV/T and it's energy, exergy and environmental analysis. • Application of sustainable solar energy PV-T dryer. It is possible to list the problems encountered in the drying of agricultural products as high energy costs and quality of the dried products. Sustainable solar dryers are needed to reduce energy costs in drying applications. The energy required to dry the product (hot air in this study) is provided by fossil fuels. This increases the amount of CO 2 released into the atmosphere. In this study, it is aimed to prevent CO 2 emitted into the atmosphere since all the energy required for drying is provided by solar energy. By using infrared technology in drying chamber the drying time of agricultural product was being shorten. In this experimental study, a new infrared-convective drying system with photovoltaic-thermal collector was designed and manufactured. Energy, exergy and environmental economics analyzes were made for different drying air mass flow rates. Excess energy is stored in batteries. Sustainable index and improvement potential values ​​were calculated using exergy analysis. As a result of this study, an average thermal efficiency of 43.75% was obtained from the PVT collector. PV panel was cooled and an average of 13.49% electrical efficiency was obtained. Average exergy efficiency was determined as 15.03%. With the use of solar energy, a system with integrated dryer was used in autumn and winter conditions. Only solar energy was used as power of the system. The use of solar energy is prevented from emitting 1.98 kg / hCO 2 to the atmosphere. In this way, a system that is environmentally friendly and compatible with nature has been obtained. CO 2 emission of the system was prevented and CO 2 cost was calculated as 2.86 ¢ / s. SI index was found in the range of 1.21–1.07 and the IP value was calculated in the range of 945–392 on average. [ABSTRACT FROM AUTHOR]

• Using HSC and FW increases daily still productivity of CSS + PTC in summer by 24.7%. • MSS + PTC + FW achieves maximum energy efficiency of 19.4. • MSS + PTC + FW achieves maximum exergy efficiency while CSS + PTC has the minimum. • MSS with PTC has the minimum freshwater cost while MSS + PTC + U has the maximum. • MSS + PTSC achieves the best performance-based exergoeconomic approach. This study experimentally investigates the performance of solar still coupled with a parabolic trough solar collector (PTSC) at different cooling rates based on energy, exergy, exergoeconomic, and enviroeconomic standpoints. Different solar still systems are considered; conventional solar still (CSS), solar still with heat sink condenser (MSS) and coupled with PTSC (MSS + PTSC), MSS having an umbrella and coupled with PTSC (MSS + PTSC + U), MSS with PTSC and condenser forced air cooling (MSS + PTSC + FA), and MSS + PTSC with condenser forced water cooling (MSS + PTSC + FW). Experiments are conducted under hot climate conditions of Sohag city, Egypt. Results indicated that the freshwater yield of all studied systems in ascending order is as follow; CSS + PTSC, MSS + PTSC + U, MSS + PTSC, MSS + PTSC + FA, and MSS + PTSC + FW in summer with value of 7.74, 8.02, 8.68, 9.11, and 9.45 kg/m2, respectively. The maximum exergy efficiency of 1.34% in summer is achieved in case of MSS + PTSC + FW system. The economic analysis shows that distilled water cost is minimum for MSS + PTSC + FW (~0.02 $/L), while it is maximum for MSS + PTSC + U (~0.022 $/L). It can be concluded that high freshwater production and less distilled water cost are making the enhanced solar desalination system feasible and competitive. Minimum exergy efficiency occurs in case of CSS + PTC with a value of 1.197% and MSS has higher average daily exergy efficiency. MSS + PTSC achieves the best performance-based exergoeconomic approach. MSS + PTSC + FW is by far the best system in cutting down CO 2 emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. • Solar enhanced char-cycling biomass pyrolysis process was modeled for the first time. • In SCCP process, pyrolysis has the highest exergy destruction due to no combustion. • Due to the external biochar, the SCCP process showed the highest CH 4 and CO yields. Pyrolysis is an efficient technology for converting biomass into value-added products, characterized by endothermal reactions. The introduction of induced solar irradiance can boost product yields and reduce carbon emissions associated with incineration. However, direct solar pyrolysis faces challenges due to difficulties in maintaining a clean solar window, which is essential to ensure efficient sunlight penetration. To address this issue, a novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. In this work, to demonstrate the potential of solar enhanced biomass pyrolysis process as a promising biomass treatment technology, energy and exergy analyses of Autothermal Pyrolysis (AP), Solar Direct Pyrolysis (SDP), and Solar Char-Cycling Pyrolysis (SCCP) processes were studied in Aspen Plus. The results showed that SCCP has the highest energy and exergy efficiencies, which were 90.81% and 76.51%, respectively. In comparison, the solar energy utilization efficiency of char-cycling was 82.18% due to the high radiative heat absorptivity of biochar. Meanwhile, the energy efficiencies for AP and SDP were 87.17% and 80.23 %, respectively. The lower efficiency of SDP was attributed to window contamination. When the solar adsorption efficiency of the SDP process falls below 82.18%, it leads to a lower efficiency than the SCCP process. Through the energy analysis, it was proved that in the SCCP process, solar energy could fully cover the pyrolysis energy requirement since it overcame the problem of window contamination. Through the exergy analysis, it was shown that the SCCP process has the highest exergy efficiency compared to AP and SDP, which was caused by avoiding biochar incineration and enhanced solar energy utilization. This study gives a comprehensive evaluation of biomass solar pyrolysis applications, with the char-cycling method presenting an innovative approach for the efficient utilization of solar energy. [ABSTRACT FROM AUTHOR]

Abstract This paper describes the design and energy, exergy, exergoeconomic and environmental (4E) performance analysis of a distributed-generation solar-assisted CCHP (combined cooling, heating and power) gas turbine system. The solar energy is used by the integration of solar parabolic trough collectors (SPTC) that are used to preheat compressed air before its introduction into the Brayton cycle combustor. An absorption chiller/heater and a heat storage tank are incorporated for producing chilled/hot water for space cooling or heating and domestic hot water, respectively. The results indicated that the energy and exergy efficiencies are 83.6% and 24.9% in the cooling operation mode, and 66.0% and 25.7%% in the heating mode, respectively. Compared to the system without solar energy, the carbon emission reduction ratio per unit energy generation of the proposed hybrid system is approximately 41.0%. The off-design analysis demonstrated that the evaluation using only energy and exergy efficiencies cannot describe the contribution of solar energy in the hybrid system. Adapting the exergoeconomic method based on energy level, the unit exergy costs of electricity, chilled water in the cooling mode (or hot water in the heating mode) and domestic hot water in the market pricing strategy are 2.1, 7.8 and 8.3 times than the natural gas's cost respectively. Highlights • Propose a gas turbine DES integrated with solar parabolic trough collectors. • Present the analysis of energy and exergy performances on the design and off-design conditions. • Allocate the products' cost using the exergoeconomic method with energy level. • Discuss the carbon dioxide emission reduction benefits of the hybrid DES. [ABSTRACT FROM AUTHOR]

In this paper, the effect of gasoline fumigation on the performance, emission, energy and exergy balance of a direct injection diesel engine is experimentally investigated. Gasoline fumigation is induced at three different ratios based on energy. In the present study, computer-controlled injection using LabVIEW software is attempted for gasoline fumigation and common rail is used to inject at the same pressure always. The characteristics of the engine are studied with and without fumigation. Results reveal that gasoline fumigation increases the energy and exergy efficiency to about 5% at medium and high loads. For all the operating points, the percentage of energy and exergy transfer through the exhaust gases decreases by an average of 2.6% using gasoline fumigation. Fumigation decreases diesel fuel consumption by 33.53%, CO2 emissions by 5.8%, NOx by 10.4% and smoke by 13-17% during full load at 30% of gasoline fumigation. Also, fumigation increases brake thermal efficiency by 3.78%, CO emissions from 0.2 to 0.96% by volume and UBHC emissions from 51 to 205 ppm during full load at 30% of gasoline fumigation. Results show that the gasoline fumigation replaces diesel and reduces both nitrogen oxides and smoke. [ABSTRACT FROM AUTHOR]

This work presents performance analysis of a novel multi-pass solar air collector with perforated fins (MPSACF) in winter conditions, Ankara province, Turkey. The aim of this work is to experimentally test and compare the performance of the two different design of solar collectors in the same climatic conditions. In addition, a double-pass solar air collector without fins (DPSAC) at the same absorber area was manufactured and tested as a control group. The total absorber area of both solar collectors is 0.325 m2. Thermal effects for performance improvement of the collectors have been designated. Average thermal efficiency values of DPSAC and MPSACF were calculated as 47.85% and 51.86%, 67.10% and 72.86%, respectively in experiments performed at 0.0069 kg/s (0.7 m/s air velocity) and 0.0087 kg/s (0.9 m/s air velocity) mass flow rates. Exergy efficiency of DPSAC and MPSACF were 2.10-17.12% and 8.74-23.97%, respectively. Coefficient of performance (COP) values were calculated 4.63 and 4.94, 3.18 and 3.48 respectively in experiments performed at 0.0069 kg/s and 0.0087 kg/s mass flow rates. Although the MPSACF has high efficiency values, COP values are lower due to the presence of dual fans. Because of their high thermal efficiency, both collectors can be effectively practiced for applications such as preheating, space heating and ventilation, greenhouse heating and product drying. [ABSTRACT FROM AUTHOR]

In this work, photovoltaic thermal-compound parabolic concentrators (PVT-CPC) are integrated to a single slope solar still (SS-SS) through a heat exchanger placed in the basin. A continuous water flow is provided over the condensing cover of SS-SS for yield enhancement. An effect of cooling condensing cover on energy and exergy analysis (thermal and electrical) together with the production cost of distilled water (₹/kg) has been studied for the following three cases: (I) the proposed partially covered photovoltaic thermal-compound parabolic concentrator single slope solar still (PVT-CPC-SS-SS), (II) fully covered thermal-compound parabolic concentrator single slope solar still (PVT-CPC-SS-SS), and (III) flat plate thermal-compound parabolic concentrator single slope solar still (FPC-CPC-SS-SS). Design parameters have been optimized for maximum distillate output (energy) and exergy on annual performance basis. Moreover, higher daily yield (37.9 kg) is obtained for case (iii). In addition, higher electrical module efficiency (13%) is obtained for case (ii) for the month of January when the solar cell temperature is 55 °C at the optimized conditions. However, the proposed system gives daily yield (35.78 kg) and generates electricity at module efficiency of 12%. The energy payback time of the proposed system is estimated to be 2 years. [ABSTRACT FROM AUTHOR]

In this paper, a simplified comprehensive multistep kinetic mechanism for fast pyrolysis was integrated with secondary and homogeneous reactions to evaluate the energy and exergy of the process. The kinetic mechanism was implemented in a two-dimensional multifluid model, which was able to reproduce experimental product yields and compositions. The results showed that the energy and exergy yields of noncondensable gas increased with temperature, while those of char decreased. The bio-oil energy and exergy yields were maximized at 500 °C. The results also showed that cellulose had the highest bio-oil energy and exergy yields, while lignin extraction with low Lig-O had superior energy and exergy efficiencies. A higher feeding rate was found to result in considerably higher energy and exergy efficiencies, and the recycled char was sufficient to supply heat for the reactor at a biomass feeding rate of ≥1.5 kg/h for all fluidization velocities. A capacity rate parameter was proposed for a sustainable pyrolysis reactor with high biomass conversion and performance. This model provides a useful reference for reactor scale-up and optimization. [Display omitted] • Energy and exergy analyses of pyrolysis were performed. • Energy and exergy yields strongly correlated with the pyrolysis product yields. • Lignin extraction with low Lig-O had superior energy and exergy efficiencies. • A reactor capacity rate was proposed as a parameter for a reactor scale-up. [ABSTRACT FROM AUTHOR]

Solar air heating (SAH) is a low-cost method for air heating using solar energy. An energy and exergy performance is performed experimentally on new designed tubular SAH having tubular absorber of adjacent tubes forming flat pack. Each tube of the absorber contains three adjacent internal tubes forming nabla shape (∇). The nabla tubular SAH (∇TSAH) performance is studied compared to ordinary tubular SAH (OTSAH) having tubular absorber only for single pass (SP) and double pass (DP) flow conditions and different mass flow rates of air (MFRA). The study is investigated under upper Egypt hot climate conditions and 0.018–0.081 kg/s MFRA. The results demonstrate that ∇TSAH has higher outlet air temperature, energy gain, higher energy, exergy, and thermohydraulic efficiencies, and lower top losses than the OTSAH. The new design boosts the exit air temperature by about 13.5 and 5 °C for SP and DP, respectively compared to OTSAH. Moreover, it enhances the energy efficiency by about 28.1% and 71.5% and the exergy efficiency by about 56.2% and 76.8% compared to OTSAH and flat plate SAH (FSAH), respectively at 0.027 kg/s. The maximum ∇TSAH output net energy gain is achieved at 0.072 kg/s for SP and 0.036 kg/s for DP. [Display omitted] • Energy and exergy of new designed Nabla-shaped SAH are investigated experimentally. • Maximum outlet air temperature rise is 50.2 °C for ∇TSAH and 36.7 °C for OTSAH. • ∇TSAH performance is greater than that of OTSAH and the latter is greater than that of FSAH. • Average daily energy efficiency is 88.4% for ∇TSAH, 77.3% for OTSAH, and 72% for FSAH. • Average daily energy efficiency is 3.89% for ∇TSAH, 2.49% for OTSAH, and 2.2% for FSAH. [ABSTRACT FROM AUTHOR]

In this article, a thermodynamic model is developed for analyzing the energetic and exergetic performance of a solid oxide fuel cell (SOFC) integrated combined power system with triple pressure reheat cycle in the bottoming steam turbine (ST) plant. A temperature difference range of 15–20 °C is considered between flue gas and steam at superheater inlet in the high and intermediate pressure stages of the heat recovery steam generator (HRSG). Also, a temperature difference of 20 °C is maintained at the pinch point between flue gas and saturated water in the low pressure stage of the HRSG. Detail performance variation is provided as a function of compressor pressure ratio (CPR) showing that the system’s power and efficiency increase while total irreversibility decreases at higher CPR. Further, thermodynamic modeling is done for two other systems with dual pressure reheat and single pressure ST cycles for performance comparison amongst all, under identical conditions. The comparative study shows that the system with single pressure ST cycle performs better compared to the others; the highest power is obtained from this system with minimum total irreversibility. It is recommended that the system with single pressure ST cycle would be the most appropriate as it is simple with less number of components and minimum total cost. [ABSTRACT FROM AUTHOR]

The operational flexibility of coal-fired combined heat and power (CHP) plants is critical for the power grid to accommodate high-penetration renewable energy. Flexibility renovations, including the high back-pressure (HBP) renovation and the low-pressure turbine zero power output (LZPO) renovation, are integrated within CHP plants and can enhance the heat-power supply flexibility. In this study, the existing two renovations are compared in consideration of flexibility, energy and exergy performance. The performance assessment of the novel CHP plant integrating with flexibility renovations are conducted. Quantitative analyses are then conducted on a characteristics day. Results show that compared with the HBP renovation, the LZPO renovation presents greater potential to improve the accommodation of renewable energy and energy efficiency, whereas is not satisfactory in larger exergy loss. Besides, compared with the conventional plant, the feasible peak-shaving capacity and heating capacity of the novel renovated plant are improved by 43 MW and 320 MW, respectively. The maximal energy utilization efficiency increases from 71.70% to 80.91%, and the exergy loss decreases from 216.9 MW to 151.2 MW. Moreover, the accommodation of renewable energy increases by 5.1 million kWh while the standard coal consumption rate for power generation decreases from 248.3 g/kWh to 222.3 g/kWh. • Flexibility renovations improve the heat-power supply flexibility of CHP plants. • Two renovations are compared in terms of flexibility, energy and exergy. • Both unit-level performance and plant-level performance are assessed. • The accommodation of renewable energy is increased by 5.1 million kWh in one day. • Coal consumption rate for power generation decreases from 248.3 g/kWh to 222.3 g/kWh. [ABSTRACT FROM AUTHOR]

There has been a theoretical investigation for energy, exergy, and economic evaluation of thermal regulation of PV panels via an innovative hybrid cooling system of flat heat pipes (HPs) coupled with phase change material (PCM). PV panel dissipates its heat through the HP evaporator while the HP condenser is cooled by PCM. The cooling system performance is investigated for different PCM quantities and types (RT42, RT35HC, and SP31) for summer and (RT21, RT18HC, and SP15-gel) for winter conditions in Egypt. A thorough study and analysis have been conducted for the impact of the cooling system on PV panel's temperature, electric efficiency, output power, PCM energy storage, and system efficiency. The results show that compared with conventional PV, the best PCM type for PV performance in summer is SP31 of 3 cm thickness, which achieves a maximum PV temperature reduction of 20.6 °C with a maximum improvement in PV electric efficiency of 11.5%. SP15-gel of thickness 2.5 cm is the best PCM for winter conditions, achieving 14.1 °C temperature reduction with 7.2% enhancement in PV electric efficiency. The exergy efficiency of the PV panel is higher than in PCM, where it rises as the phase change temperature of the PCM increases. PV maximum average daily exergy efficiency is 13.4% for SP15-gel, compared with 12.71% for conventional PV in winter, while SP31 achieved 12.25%, 1% higher than reference PV in summer. PCM's maximum average daily exergy efficiency is 0.69% and 0.7% for RT42 and RT21 in summer and winter, respectively. The minimum payback period for conventional PV is about 18.01 years, while it is approximately 13.39 years for PV with HP and PCM. The studied cooling system at different PCMs proves its capability to enhance the PV performance with higher energy and exergy efficiencies and lower cost and store the excess heat inside the PCM. [Display omitted] • Energy, exergy, and economic assessment of PV/HP- PCM cooling system is studied. • The impact of PCM type and quantity is considered at different climates conditions. • 20.6 °C and 14.1 °C PV temperature reductions were achieved using SP31and SP15-gel, respectively. • The exergy efficiency of the PV panel is higher than that of PCM. • HP-PCM cooling system efficiently regulates PV operating temperature at a lower cost. [ABSTRACT FROM AUTHOR]

• Energy and exergy performance of F135 PW100 are analyzed. • Effects of flight-Mach number, flight altitude, and fuel types have been examined. • Effects of inlet air temperate have been investigated. • An intelligent model based on the deep learning method is attained. • Behavior of the considered engine in different flight conditions can be predicted. In the present study, the effects of flight-Mach number, flight altitude, fuel types, and intake air temperature on thrust specific fuel consumption, thrust, intake air mass flow rate, thermal and propulsive efficiecies, as well as the exergetic efficiency and the exergy destruction rate in F135 PW100 engine are investigated. Based on the results obtained in the first phase, to model the thermodynamic performance of the aforementioned engine cycle, Flight-Mach number and flight altitude are considered to be 2.5 and 30,000 m, respectively; due to the operational advantage of supersonic flying at high altitude flight conditions, and the higher thrust of hydrogen fuel. Accordingly, in the second phase, taking into account the mentioned flight conditions, an intelligent model has been obtained to predict output parameters (i.e., thrust, thrust specific fuel consumption, and overall exergetic efficiency) using the deep learning method. In the attained deep neural model, the pressure ratio of the high-pressure turbine, fan pressure ratio, turbine inlet temperature, intake air temperature, and bypass ratio are considered input parameters. The provided datasets are randomly divided into two sets: the first one contains 6079 samples for model training and the second set contains 1520 samples for testing. In particular, the Adam optimization algorithm, the cost function of the mean square error, and the active function of rectified linear unit are used to train the network. The results show that the error percentage of the deep neural model is equal to 5.02%, 1.43%, and 2.92% to predict thrust, thrust specific fuel consumption, and overall exergetic efficiency, respectively, which indicates the success of the attained model in estimating the output parameters of the present problem. [ABSTRACT FROM AUTHOR]

Abstract: An experimental setup to investigate the thermal performance of a cylindrical cavity receiver for an SK-14 parabolic dish concentrator is presented in this technical note. The thermal performance is evaluated using energy and exergy analyses. The receiver exergy rates and efficiencies are found to be appreciably smaller than the receiver energy rates and efficiencies. The exergy factor parameter is also proposed for quantifying the thermal performance. The exergy factor is found to be high under conditions of high solar radiation and under high operating temperatures. The heat loss factor of the receiver is determined to be around 4.6W/K. An optical efficiency of around 52% for parabolic dish system is determined under high solar radiation conditions. This experimental setup can be used as teaching tool for people with little or no knowledge about solar dish concentrators due its simplicity and the basic mathematical formulations applied. Different types of receivers and different types of deep focal region parabolic dishes can also be tested with the experimental setup. [Copyright &y& Elsevier]

Abstract: Solar cookers may be generally classified into direct and indirect types. The direct types include the box type and parabolic type, while the indirect types include the vacuum tube based cookers. This paper reviews the gradual progress made in the second type. The energy and exergy analysis of a single vacuum tube based prototype has been carried out experimentally. Performance parameters indicate a high peak exergy power of 55.6W, while the temperature difference gap at half power is 38.75K and the quality factor is 0.042. The energy efficiency of the cooker is 20–30%, while the exergy efficiency is 4–6%. These results make this compact single family solar cooker comparable in performance to large community based Scheffer type solar cookers. Results have been compared to a number of other solar cooker types. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of hybrid photovoltaic thermal (PVT) water collectors under constant collection temperature mode unlike constant flow rate mode. The analysis has been carried out in terms of thermal energy, electrical energy and exergy gain for two different configurations namely case A (collector partially covered by PV module) and case B (collector fully covered by PV module). The results are compared with the conventional flat plate collector (FPC). The effect of collector area covered by PV module on the performance of hybrid PVT water collector has been studied. The characteristic equations have also been developed for both the cases. It has been observed that case A is more favorable for thermal energy point of view, while case B is suitable for electricity generation. On the basis of the numerical calculations the annual thermal energy gain is found to be 4167.3 and 1023.7 and annual net electrical energy gain is 320.65 and 1377.63 for cases A and B respectively. The annual overall thermal energy gain is decreased by 9.48% and an annual overall exergy gain is increased by 39.16% from case A to case B. [Copyright &y& Elsevier]

In the current research, the energy, exergy, environmental and economic (4E) analyzes of a PEM fuel cell are investigated. Parameters related to exergy are studied by considering the environmental effects and operating conditions of the PEM fuel cell. Multi-objective optimization is applied to maximize output power and efficiency and minimize environmental impacts and cost. The fuel cell is simulated with coolant channels and the effects of using porous metal foam inside the gas channels and coolant channels are investigated on the distribution of hydrogen and liquid water. The effect of using a hybrid nanofluid as a high potential liquid to keep the fuel cell cool is investigated. Optimal output power and optimal cost are provided according to the number of different cells. Optimal efficiencies (energy and exergy) and optimal environmental characteristics are likewise presented in a wide range of current densities. The results show that the simultaneous use of nanofluid and porous metal foam for cooling the fuel cell may not be appropriate. Furthermore, the effect of using metal foam is recommended for better cooling (increased heat transfer) of the fuel cell. Likewise, the use of porous metal foam inside the anode channel affects the distribution of hydrogen and liquid water. The effect of using porous foam in Re = 300 and above is significant so that in Re = 300, a 48% increase in heat transfer compared to the channel without porous foam can be seen. Besides, the percentage of reduction of nanofluid heat transfer in the presence of porous foam (in Re = 500) compared to pure water is 7.5%. • Energy, exergy, environmental and economic analysis (4E) of a PEM fuel cell is performed. • Multi-objective optimization is applied to maximize output power and efficiency. • Simultaneous use of nanofluid and porous metal foam for cooling may not be appropriate. • Effect of using metal foam for better cooling is recommended. • Use of porous metal foam inside the anode channel affects the distribution of hydrogen and liquid water. [ABSTRACT FROM AUTHOR]

This article proposed a multifunctional PV/T (MFPV/T) wall with the built-out PV cells. While generating electricity, this system could produce warm air in heating seasons and hot water in non-heating seasons. Besides, this novel structure could solve the issue of unreliability of the conventional PV/T collectors. In this work, firstly, the thermal and electrical performance of the proposed system was tested in a civil building. Then, the performance comparison between the MFPV/T walls with the built-out and built-in PV cells (EMFPV/T and IMFPV/T walls) was conducted based on the validated simulation models. Finally, the impact of change in parameters on the system performance was analyzed. The main results were: (1) During the experimental period, the thermal and electrical efficiencies were 17.55% and 13.88% in PV/air mode while those were 8.92% and 14.09% in PV/water mode. (2) During the studied three days, the exergy of the EMFPV/T wall was higher than that of the IMFPV/T wall by 390 Wh for PV/air mode and 750 Wh for PV/water mode. (3) Decreasing cavity depth and increasing vent airtightness, PV coverage ratio, and water tank volume had different effects on the energy output, but they all increased the exergy production. • A multifunctional PV/T wall with the built-out PV cells was proposed. • The thermal and electrical performance of the proposed system was tested in a civil building. • The comparison with the system with the built-in PV cells was conducted. • The impact of change in parameters on the performance of the proposed system was analyzed. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the thermodynamic analyses of single layer drying process of pumpkin slices via cyclone type dryer. Using the first law of thermodynamics, energy analysis was performed to estimate the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during drying process by applying the second law of thermodynamics. It was concluded that the exergy losses went up with the increase of the energy utilization in both trays and drying chamber. The most exergy losses took place during the drying of pumpkin slices on the first tray. It is emphasized that pumpkin slices are sufficiently dried in the ranges between 60 and 80°C and 20% and 10% of relative humidity at 1 and 1.5ms−1 of drying air velocity during 5.66–12h despite the exergy losses of 0–1.165kJs−1. [Copyright &y& Elsevier]

This paper is concerned with thermodynamic analysis of the process of single-layer drying of apple slices by means of a cyclone-type dryer. Using the first law of thermodynamics, energy analysis was performed to estimate the ratios of energy utilization throughout the drying process. Exergy analysis was carried out to determine exergy losses during the drying process by applying the second law of thermodynamics. It was concluded that the exergy losses increased with increasing energy utilization in both trays and the drying chamber. Values of the energy utilization ratio (EUR) of the drying chamber varied in the range 0–41.64 per cent depending on the drying conditions. The most exergy losses took place on the first tray (EUR = 0–21.06 per cent) during the drying of apple slices. It is emphasized that apple slices are sufficiently dried in the range 60–80 °C with 20–10 per cent relative humidity and a drying air velocity of 1.5 m/s over a 3.33–5.33 h period in spite of exergy losses of 0–1.243 kJ/s (EUR = 0–34.72 per cent). [ABSTRACT FROM AUTHOR]