Average Solar Fraction Research Articles

Integration of energy storage and determination of optimal solar system size for biomass fast-pyrolysis

This study presents a model and analysis of a heliostat field collector (HFC) system integration with fast-pyrolysis of biomass and determination of the optimal solar system size for this integrated system. Given the intermittent nature of solar energy, an auxiliary heater and a thermochemical energy storage system (TCES) are included. Four cases of HFC integration with the fast-pyrolysis process have been studied: 1) low solar radiation, 2) sufficient solar radiation, 3) high solar radiation, and 4) no solar radiation with available stored energy in TCES. The solar energy system was modeled and calculated using the Engineering Equation Solver (EES) software, while the fast-pyrolysis process and the TCES were simulated using the Aspen Plus software. A thermodynamic and economic analysis has been conducted to estimate the share of solar energy for different process configurations. Economic calculations have been conducted for three different heliostat filed areas: 4000, 8000, and 12000 m2. Solar fraction, investment and operational costs, as well as total cost were calculated for these three heliostat field areas. The results indicate that the optimum heliostat field area for the studied biomass pyrolysis plant is 8000 m2 and the average solar fraction of the required energy in summer is 0.39 and while it is 0.34 for the whole year. Simulation results considering this optimized heliostat filed area indicate that 6.27 t/h of bio-oil is produced from 10 t/h of hybrid poplar biomass. Implementing this solar-assisted system reduces CO2 emissions, increases efficiency of the system and lowers thermal energy requirement for the fast-pyrolysis process from 6MW to 3.99MW.

Thermoeconomic Analysis of a Solar-Assisted Industrial Process Heating System

Thermal energy in the industrial sector for process heating applications in the range of 50 to 250°C consumes about 35% of the global fossil fuel. Cascaded solar thermal systems are promising solutions to meet clean and uninterrupted thermal energy supply for industrial process heating. Well-engineered cascaded arrangement of solar thermal collector (STC) and photovoltaic thermal (PVT) collector can attain an average solar fraction of more than 50%. In the present research, a solar-assisted process heating system, wherein a STC integrated in series with PVT, has been designed to produce low- to medium-temperature heat at higher solar fractions. Herein, thermal performance and economic viability of this novel system have been investigated and analyzed methodically. In the present research, a comprehensive TRNSYS simulation model is developed and validated experimentally. Results show that PVT integrated with heat pipe evacuated tube collector (PVT-HPETC) and PVT integrated with flat plate collector (PVT-FPC) system can generate thermal energy as high as 1625 and 1420 W with a thermal efficiency of 81 and 77% and exergy efficiency of 13.22 and 12.72%. Levelized cost of heat (LCOH) for PVT-HPETC at process heat temperatures of 60, 70, and 80°C is 0.214, 0.208, and 0.201 MYR/kWh, respectively. It is worth to note that LCOH is less than the existing cost of heat generation which proves that these systems are economically feasible.

Assessing the feasibility of off-grid photovoltaic systems for rural electrification

In this investigation, the absence of an electricity grid in numerous locations, including military bases, tiny houses, and chalets, prompted the development of a model for providing electrical energy through an off-grid Photovoltaic (PV) system in Konya, Türkiye. The study delineates the daily energy consumption of a residential dwelling as 39,974 Wh/day, and the feasibility of satisfying this demand through the implementation of a 9.45 kWp PV system is scrutinized. The research encompasses the determination of optimal tilt and azimuth angles set at 35° and 0°, respectively. The maximum global effective irradiation intensity, recorded in August at 208.3 kWh/m², contrasts with the minimum intensity observed in December, registering at 106.2 kWh/m². Likewise, electricity production attained its zenith in August at 1,581.3 kWh, starkly contrasting its lowest level in December at 791 kWh. Modelling outcomes conclude that Solar Fraction (SF) values equate to unity during summer but fall below unity during winter. Furthermore, a surplus in electricity generation relative to demand is observed during the summer, resulting in the full charge of batteries. Evaluating the annual average SF, it is deduced that the modelled system fulfils 90.8% of the energy requirement. The Performance Ratio (PR), an additional pivotal parameter in PV systems, reaches its zenith at 0.865 in November and its nadir at 0.614 in August. This comprehensive study underscores the efficacy of the modelled off-grid PV system in meeting the energy demands of the selected residence, emphasizing the significance of seasonal variations and key performance metrics in assessing system performance.

Active solar heating system for residential building in Algeria An energetic economic and environmental investigation

In this work we used a typical single family house in Algeria as an example, the influence of building type on the energetic efficiency of an integrated solar combisystem (SCS) is determined by means of numerical simulation using TRNSYS software program. We considered two types of buildings, which have the same size and the same orientation. The first one is a low energy pilot house performed by CDER 'Centre de Développement des Energies Renouvelables' and CNERIB 'Centre National d’Etudes et Recherches Intégrées du Bâtiment' in the framework of MED-ENEC project, however, the second considered house is a virtual building; in which the walls are of the conventional type in Algeria. Based on the obtained results, it is outlined how the total system load can be decreased by adopting some solar architecture techniques. The analysis of the auxiliary energy required by the solar combi system and the average solar fraction; shows the profitability of the SCS application in Algeria, especially in the case of low energy house. Furthermore, the economic aspect and the environmental impacts of the integrated solar heating system have been investigated. The equity payback and greenhouse gas 'GHG' emissions have been estimated by means of a numerical simulation using the powerful tools of the RETScreen free software program. The obtained results showed that the equity payback is strongly dependent on the fuel used by the conventional heating system. In the case, where the heating is assured by the gasoil, the equity payback is around the half of the project lifetime. From the environmental standpoint, the solar application is entirely advantageous. In addition, the natural gas is the most favourable conventional energy resource, with a minimum yearly GHG emissions compared to electricity and gasoil.

Experimental optimization of the heating element for a direct-coupled solar photovoltaic water heater

In the last few years, the price of photovoltaic (PV) modules has decreased significantly. As a result, solar PV has become an interesting option for water heating. In a direct-coupled PV water heater (DPVWH) system, the PV array is directly connected to the heating element. Therefore, the optimization of the heating element resistance value is an essential step to design a DPVWH system. This research aims to optimize the resistance value of the heating element for different climatic conditions (Montreal and Bagotville in Canada, and Fez in Morocco). Simulation models were developed using MATLAB/Simulink and TRNSYS software to evaluate the performance of a PV system directly connected with the heating element over a one-year period. This simulation model was validated with an experimental setup. The coefficient of determination (R2) ranges from 98.75% to 99.89%. The results of the experimental optimization indicate that in areas with high incident solar irradiation, the optimal resistance value is low, while the opposite is true for areas with lower solar irradiation. Furthermore, it is found that a direct-coupled PV water heater with a capacity of 3000 Wp achieves an average annual solar fraction of 41% in Montreal, and 73% in Fez. Additionally, the simulation results show that the use of an MPPT (Maximum Power Point Tracking) controller could increase the PV energy production by 29% in average. However, a direct-coupled PV solar water heater system is recommended for a remote and cold region, due to its robustness, its low operating cost, and its simplicity.

Effects of heat source type on the thermodynamic performance and economy of domestic hot water system

In this paper, a solar assisted air source heat pump (SA-ASHP) domestic hot water (DHW) system is designed and built, the thermal performance of the system and the effect of heat source type on the energy consumption and carbon emission are studied by simulation and experiment. The static investment payback period of transforming the auxiliary heat source from electric boiler (EB) to ASHP is determined by economic analysis. The results show that the coefficient of performance of SA-ASHP system (COPS) varies from 2.76 to 6.26 and the coefficient of performance of ASHP unit (COPH) varies from 2.62 to 3.93 throughout the year. In the four typical heat source hot water systems, the SA-ASHP system has the lowest energy consumption, operation cost and CO2 emission. Compared with the solar assisted electric boiler (SA-EB) system, the power consumption per unit hot water, per capita power consumption and per capita water consumption of the SA-ASHP system decreased significantly, while the average heat collection efficiency and solar fraction increase obviously. Based on the actual operation data and economic analysis, the static payback period and CO2 emission reduction of transforming a SA-EB system into a SA-ASHP system have been analysed.

Investigation of solar powered sorption cooling and heating systems to supply hospital’s thermal requirements in pandemic periods

Abstract In pandemic periods such as COVID-19, economic and sociological problems threaten human life and public order on a global scale. In these periods, the use of solar powered heating–cooling systems to meet the thermal needs of hospitals and to provide thermal comfort conditions offer important solutions for the elimination of technical, economic and environmental problems related to energy supply. In this study, the heating, cooling and hot water supply of a sample hospital building for the three largest cities of Turkey with a novel solar powered Li-Cl absorption heat pump system was investigated using the Transient System Simulation Tool (TRNSYS) simulation program. The use of a unique NH3-H2O resorption system as a solar powered auxiliary system was also investigated. It was determined that the total annual hot water and cooling needs of the hospital buildings in all three provinces are supplied almost completely by the solar energy powered system without compromising the hygiene and thermal comfort of the occupants. The average annual solar fraction of total heating demands are calculated as 50, 54 and 65% for İstanbul, Ankara and İzmir, respectively. In addition, depending on the use of solar energy, it has been observed that 126 tons of CO2 emissions were saved annually, and an economic saving of 524 375 TL was achieved in total. Considering the problems with energy supply during the epidemic periods, it was concluded that meeting the energy requirements of hospitals with clean, renewable and independent energy source will provide significant benefits to the countries.

Performance assessment of a solar-assisted absorption-compression system for both heating and cooling

Combining renewable energy with building energy supply is an effective way to pivot the building sector to carbon–neutral. This paper proposes a novel solar-assisted energy supply system which is applied in residential buildings for heating, cooling and domestic hot water. The heating/cooling output of the proposed system is mainly contributed by a vapor compression system to address the supply–demand mismatch of solar energy supply system, and the other part is assumed by a solar driven absorption system that is operating with lower generation temperature and higher evaporation temperature to assist the vapor compression system. Therefore, a solar-assisted absorption-compression system (SAACS) exploits the full potential of solar heat for annual energy supply by improving the contribution of per unit solar collection area, with considerable electricity-saving compared to air-source heat pumps. A thermodynamic model is established and validated by the results of the built experimental prototype which is testing. Solar-assisted heating mode and solar-assisted cooling mode are compared in comprehensive evaluation criteria to illustrate the performance differences caused by the assisted solar energy. The results indicate that solar heat at 60 °C is feasible for heating and cooling, revealing the great potential for efficient conversion from solar energy for heating and cooling. Due to the introduction of solar energy, the cooling and heating COPele increases by 10.3 % ∼ 17.6 % and 32.3 % ∼ 56.3 %, respectively. Despite the lower increase in COPele, electricity-saving ratio shows greater value at low hot water temperatures, varying from 24.3 % to 19.6 % for cooling and from 44.1 % to 39.7 % for heating as hot water temperature increases from 60 °C to 85 °C. The maximum SCOP is 0.63 for cooling, and 1.14 for heating. Yearly investigation shows that the SAACS combined with 20 m2 CPC collector has an annual average solar fraction of domestic hot water of 0.85 and a discounted payback period of 3.12 years. These results demonstrate the feasibility and flexibility of the SAACS applied to residential buildings toward decarbonization.

Performance Evaluation and Statistical Analysis of Solar Energy Modeling: A Review and Case Study

The main target of this research is a quantitative review of literature on global solar radiation (GSR) models available for different stations around the world. The statistical analysis of 400 existing sunshine-based GSR models on a horizontal surface is compared using 40-year meteorological data in the selected locations in Egypt. The measured data is divided into two sets. The first sub-data set from 1980 to 2019 was used to develop empirical correlation models between the monthly average daily global solar radiation fraction (H/H0) and the monthly average of desired meteorological parameters. The second sub-data set from 2015–2019 was used to validate and evaluate the derived models and correlations. The developed models were compared with each other and with the experimental data of the second subset based on the statistical error indicators such as RMSE, MBE, MABE, MPE, and correlation coefficient (R). The statistical test of the correlation, coefficient (R), for all models gives very good results (above 0.92). The smallest values of t-Test occur around the models (M 272, M 261, M 251, and M 238). The accuracy of each model is tested using ten different statistical indicator tests. The Global Performance Indicator (GPI) is used to rank the selected GSR models. According to the results, the Rietveld model (Model 272) has shown the best capability to predict the GSR on horizontal surfaces, followed by the Katiyar et al. model (Model 251) and the Aras et al. model (Model 261).

Feasibility study using TRANSYS modelling of integrating solar heated feed water to a cogeneration steam power plant

A feasibility of feed water heating of a 62 MW cogeneration power plant, Shoaiba, KSA, (21 °N) through integrated parabolic trough solar collectors has been technically and economically provided. Extracted steam from turbine to the highest-pressure feed water heater (FWH) is replaced by the solar collectors. A transient simulation model was created by TRNSYS simulation software to find the annual performance of the power plant integrated with solar system. The power block simulation results were validated with the designed data of the conventional power plant. The annual performance of the system was estimated as the average solar power generation and solar fraction. Economic feasibility analysis was considered in this work to estimate the life cycle savings (LCS), levelized cost of energy (LCOE), payback lifetime and amount of fuel saved. It was found optimum system sizing at which the system has the maximum LCS which equals 41.5 Million U$ at 150,000 m2. It can achieve an annual solar fraction of 28% at which the solar system can produce 1.72E+11 kJ while the payback lifetime was estimated as 14.6 years. Moreover, 4,619 tons fuel can be saved that is corresponding to 777.34 tons CO2 can be avoided annually as the environmental impact.

Technical, environmental and ranking analysis of using solar heating: A case study in South Africa

The process of heating water consumes a lot of energy. In South Africa (SA) up to 40% of household energy consumption is utilized for water heating. In this regard, the use of renewable energies, especially solar, can help reduce the energy crisis in this country. In this study, applying the solar water heaters (SWHs) in home-scale has been explored for the first time, by using climatic information for 21 cities in South Africa. The techno-environmental assessment was performed by TSOL PRO 5.5 on two types of the evacuated tube (ET) and flat plate (FP water heaters). Furthermore, these cities are ranked using GAMS 24.1 and two types of DEA methods. The results indicate the efficiency of evacuated tube SWHs is better than that of flat plate SWHs at all cities and if we use the FP water heater, the average solar fraction is 95.93%, which prevents about 23.5 tons of CO2 emissions annually. These values for ET water heaters are 99.16% and 24.4 tons per year, respectively. For the FP collector, the findings indicate Beaufort West, Mmabatho and Welkom cities are preferable cities in both models, DEA-CCR and DEA-Additive models.

Energy and exergy analysis of a water bed‐infrared dryer coupled with a photovoltaic‐thermal collector

AbstractOrange is a perishable fruit that is dried to increase its shelf‐life. The main challenge of industrial dryers is their high energy consumption, which accounts for about 12% to 20% of the energy demands of the industry. In the present study, a continuous water bed‐infrared dryer equipped with a photovoltaic‐thermal (PV‐T) collector was presented for orange fruit drying. The designed dryer comprised two main units: the PV‐T air collector and the water bed‐infrared dryer. The PV‐T collector was considered to simultaneously generate electricity and heat required for the hot airflow inside the dryer. The effects of the hot water flow rate (0.05, 0.1, and 0.15 L/min) and the product thickness (3, 5, and 7 mm) on solar heat fraction, final moisture content of the dried oranges, and energy and exergy efficiencies of the dryer were investigated using the factorial test based on a randomized complete block design experiment. The average solar heat fraction increased by 35.1% with increasing the thickness from 3 to 7 mm, and increased by 29.8% with increasing the water flow rate from 0.05 to 0.15 L/min. Rising the water flow rate in the studied range reduced the final moisture content by about 14.7%. The average solar heat fraction, final moisture content as well as energy and exergy efficiencies of the dryer were obtained 0.26–0.61, 9.1%–16.04% wet basis (wb), 26.35%–35.63%, and 3.42%–12.9%, respectively. The best operating condition suggested based on the highest solar heat fraction, energy and exergy efficiencies, and the lowest final moisture content, was the 3‐mm slice thickness of orange and the water flow rate of 0.15 L/min.Practical ApplicationsThe main challenge of industrial dryers is their high energy consumption. In the present study, to increase energy efficiency in water bed dryers, a heat source of infrared radiation was deployed on top of the product surface, and a PV‐T collector was used to generate electricity and hot airflow simultaneously. We experimentally investigated the changes in heat fraction of solar energy, final moisture content of dried oranges, and energy and exergy efficiencies of the designed continuous water bed‐infrared dryer equipped with PV‐T collector at different operating conditions.

Modeling of a solar water heating system for a private hospital in Sana’a, Yemen using TRNSYS

The objective of the present work is to simulate and analysis the performance of a proposed solar water heating system for a 160-bed capacity private hospital in Sana’a City-Yemen. The systems consist of solar collectors, hot water circulation pump, a storage tank with an electrical heater, and identical auxiliary components. The simulation and the thermal performance analysis have been done using TRNSYS software. In addition, a comparison between the performance of evacuated tubes collectors and flat plate collectors was done to justify the selection of ETC for the designed. The thermal performance analysis shows that the evacuated tubes collectors have an annual contribution of 87.73 MWh with an annual average solar fraction of 63 percent and annual average installation efficiency of 68 percent.

자연순환 태양열온수기 유동 및 열성능에 관한 이론해석

This study presents a theoretical analysis of the dynamic behavior and thermal performance of a solar water heater with an internal exchanger using a thermosiphon system. The heat exchanger, made of a helical coil, is placed in the horizontally cylindrical storage tank so that the solar hot fluid crosses a significant mass of stored water. In order to analyze the dynamic natural circulation of solar water heaters by thermosiphon, a new TRNSYS component was developed using W-language, based on a detailed mathematical model. As a result of simulation, the solar heat yield and the average solar fraction were 2,001 kWh and 75.1%, respectively. The lowest solar fraction in January was 50.5%, and then gradually increased, reaching almost 100% from May to September. Here, when the system overheating lower limit temperature is set to 90℃, it was exposed to the overheating period for about 153 hours, which is 6.5% of the annual operating time (about 2,339 hours). Secondly, the instantaneous maximum efficiency of the collector was 42.3%, and the annual average system efficiency considering the heat loss of the solar storage tank was 36.2%.

Estimation of Solar Hot Water System Operation for a Residential Building

Solar hot water supply systems can provide a significant part of the thermal energy needed in the residential sector. The use of solar hot water supply systems can reduce the consumption of traditional energy sources and, consequently, reduce greenhouse gas emissions. The aim of this article is to assess the operation of the solar heating system operation to provide the needs of the hot water supply system of a residential building with thermal energy. The efficiency of a flat solar collector operating in a single-circuit thermosyphon system of solar heating of a residential building in Lviv has been established. The solar fraction of the hot water supply system of a residential building is determined depending on the volume of hot water consumed, in particular 50, 60, 70, 80, 90, 100 l/day. It is established that the lower the need for hot water, the greater the solar fraction of the solar hot water supply system. Thus, the average annual solar fraction of the solar hot water supply system with a daily consumption of 50 l/day is 0.77, and with a daily consumption of 100 l/day the solar fraction is 0.39. The average value of the solar fraction for the solar hot water supply systems of the studied house is 0.55.

Design optimisation of a combined pellets and solar heating systems for water heating in a public bathhouse

Solar water heating system using flat plate collectors is an environmentally friendly system commonly used worldwide for low temperature applications. In this study, the main objective is to assess the economic and energy potential of flat plate collectors used in combination with modern, automatic pellet boilers for large hot water preparation in a commercial building (called Hammam or public bathhouse) under the weather conditions of Marrakesh, Morocco. Further, Annual simulations were conducted using TRNSYS software. Besides, the life-cycle savings method was carried out for the financial analysis. Further, the final configuration derived from the optimisation shows that the optimal collector area is found to be 213 m2, which provides an average solar fraction of about 48%. Indeed, the hybrid system can achieve a life-cycle savings of 82.7 k€ over the entire life of the system compared to the baseline system (Pellet boilers only). These results show that the implementation of solar thermal system in a traditional Hammam for the production of hot water has the better energetic and environmental performance compared to the reference system; therefore, the deployment of such a hybrid system will result in considerable reductions in CO2 emissions, substantial energy savings and significant progress in combating deforestation in Morocco.

Experimental investigation of Versa Tyle GRP for solar thermal system

ABSTRACT Solar thermal systems have encountered a high level of interest over the last ten years due to their low cost and convenience in reducing energy load for domestic hot water. This paper aimed to introduce a new panel’s material (Versa Tyle GRP Tiles) for solar thermal system and a prototype was built in a small shed at a site in Liverpool (UK), in order to assess its performance. The experiment was run for 12 months for the purpose of collecting and analyzing thermal data in terms of heat capacity, solar energy, and solar fraction. To simulate the daily use of water consumption and provide realistic outputs, the system was emptying every day at different durations in order to investigate the recovery period of the temperatures. The results proved the feasibility and efficiency of the Versa Tyle GRP as the maximum recorded temperature on the tiles was 68°C, and 51°C for the hot water in July; while winter months recorded a maximum of 26°C for the hot water. The system achieved average solar fraction of 36.52–47.43% between May to September, while in the rest of the months in the year, average solar fraction of 2.95%-18.59% were detected.

A New Design of an Integrated Solar Absorption Cooling System Driven by an Evacuated Tube Collector: A Case Study for Baghdad, Iraq

The electrical power consumption of refrigeration equipment leads to a significant influence on the supply network, especially on the hottest days during the cooling season (and this is besides the conventional electricity problem in Iraq). The aim of this work is to investigate the energy performance of a solar-driven air-conditioning system utilizing absorption technology under climate in Baghdad, Iraq. The solar fraction and the thermal performance of the solar air-conditioning system were analyzed for various months in the cooling season. It was found that the system operating in August shows the best monthly average solar fraction (of 59.4%) and coefficient of performance (COP) (of 0.52) due to the high solar potential in this month. Moreover, the seasonal integrated collector efficiency was 54%, providing a seasonal solar fraction of 58%, and the COP of the absorption chiller was 0.44, which was in limit, as reported in the literature for similar systems. A detailed parametric analysis was carried out to evaluate the thermal performance of the system and analyses, and the effect of design variables on the solar fraction of the system during the cooling season.

Performance analysis and optimization of a solar-air source heat pump heating system in Tibet, China

Owing to its great potential for solar energy and uniquely low relative humidity, Tibet is an ideal region for the application of solar-air source heat pump (SASHP) heating systems. This study aimed to evaluate the performance and optimize the key design parameters of a SASHP in Tibetan climatic conditions. A SASHP parallel system was designed for providing space heating in office buildings, and was modeled and simulated in transient system simulation (TRNSYS) software. The simulation results showed that for a reference SASHP system, the solar collection efficiency, with a daily average value of 0.27 and a maximum value of 0.44, is low during the entire heating season. The solar collectors could afford a high percentage of heating (even 100%) at every initial heating period. However, the overall solar fraction for heating was only 42.79% for the entire heating season. The SASHP operated with a high efficiency for most of the heating period, with a maximum coefficient of performance (COP) of 2.68 and an average COP of 1.95. Furthermore, the hot water temperature of the water tank generally varied near 45 °C, indicating that the water temperature satisfied most of the heating requirements with regard to the heating time. In the performance optimization, the optimal values for the area of the solar collector, angle of the solar collector, and volume of the water tank were found to be 225 m2, 45°, and 30 m3, respectively. The average solar fraction increased to 0.793, an improvement of 85.3% over the reference system. Furthermore, orthogonal experiment results indicated that the solar collector area and water tank volume were the priority factors for the design of a SASHP system in Tibet.

Design, Simulation, and Economic Optimization of an Off-Grid Photovoltaic System for Rural Electrification

Access to clean and affordable energy in rural African regions can contribute greatly to social development. Hence, this article proposes the design, simulation, and optimization of a stand-alone photovoltaic system (SAPV) to provide non-polluting electrical energy based on a renewable source for a rural house located in Tazouta, Morocco. Real monthly electrical demands and hourly climatic conditions were utilized. An initial design process indicated that, with a 1080 Wp total capacity of PV modules and 670 Ah of battery storage, the proposed SAPV system was able to meet a considerable part of the dwelling load with an average solar fraction of about 79.1%. The rest of the energy demand was ensured by a diesel generator (DG). Also, a life cycle analysis of the PV system revealed that the life cycle cost is 10,195.56 USD and the unit electricity cost is 0.57 USD/kWh for an initial investment of 4858.68 USD. Thereafter, an optimum design based on Homer Pro software was carried out indicating that lower PV capacity can decrease the unit energy cost to 0.356 USD/kWh while reducing the solar fraction to 54.9%.