This research shows the methodology for technical evaluations of the energy performance of absorption refrigeration systems activated with solar energy. This document determines the optimal ...installation angle of the solar thermal collectors that activate the chiller. Also, the cooling energy Qe, Coefficient of Performance (COP), and hourly Seasonal Coefficient of Performance (SCOP) are determined for each month of the year and recommendations are made for operation in the city of Culiacán, Mexico. The absorption cooling system achieved a Qe of 400.9 kW, a COP of 0.778, and a SCOP of 0.557.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The collector roof angle is an important parameter for the optimization of the SCPP.•The velocity can be raised by 125% within the SCPP for a variation of Δq=2.5°.•Computational results are ...validated using our experimental data.
The solar chimney power plant (SCPP) is a promising solution to produce electrical power from solar energy. The optimization of the solar setup geometry is required to enhance its performance. In this paper, a numerical study is presented to evaluate the performance of the solar chimney power plants while varying the collector roof angle. The considered system is defined by the collector height equal to h=50mm, the chimney diameter equal to d=160mm, the collector diameter equal to D=2750mm and the chimney height equal to H=3000mm. Four collector roof angles, equal to β=−1.5°, β=−1°, β=0° and β=1°, were investigated. For each collector roof angle, the distribution of the magnitude velocity, the air temperature, the pressure, the incident radiation and the turbulence characteristics were presented and discussed. The efficient choice of the optimal geometry is based on the calculation of the maximum value of the air velocity within the SCPP. Results indicate that a negative collector-roof positively increases the air velocity. The obtained results present an interesting data which can provide the thermal characteristics of the air flow for the designers and the engineers to improve the overall efficiency of the solar setup.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•We propose a time-dependent model for the efficiency of an NDAPSC.•Dimensional analysis reveals four controlling dimensionless numbers.•We obtain a time-dependent analytic expression of system ...temperature.•We redefine the standard instantaneous solar collector efficiency measure.
In this paper we propose a time-dependent, three-dimensional model for the efficiency of a nanofluid-based direct-absorption parabolic trough solar collector under a turbulent flow regime. The model consists of a system of equations: a partial differential equation for conservation of energy, and a time-dependent radiative transport equation describing the propagation of solar radiation through the nanofluid. Writing the model in dimensionless form reveals four controlling dimensionless numbers: one describing the relative importance of conduction and advection and three describing the heat loss to the surroundings. Realistic parameter values are applied to reduce the model further and these indicate that two of the dimensionless groups have a much smaller impact on the performance of the solar collector. We use the resulting solution for the temperature to calculate an analytic expression for the collector’s efficiency. This expression permits optimisation of design parameters such as particle loading, incoming radiative intensity, receiver dimensions, the inlet temperature, and solar concentration ratio.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Roadmap presented for hybrid photovoltaic thermal (PVT) collectors.•A novel indium tin oxide (ITO)-based transparent low-emissivity coating applied directly to a PV cell is presented.•Quantitative ...comparison of evacuated cavities, transparent low-emissivity coatings, and silicon heterojunction photovoltaic cells for improved performance.•Cost requirements for technologies along the roadmap are estimated and compared to today’s costs.
For hybrid photovoltaic-thermal collectors to become competitive with other types of solar energy converters, they must offer high performance at fluid outlet temperatures above 60 °C, as is required for space heating and domestic hot water provision, which together account for nearly 50% of heat demand. A roadmap is presented of the technological advances required to achieve this goal. Strategies for reducing convective, radiative and electrical losses at elevated temperature are discussed, and an experimental characterisation of a novel transparent low-emissivity coating for photovoltaic solar cells is presented. An experimentally-validated simulation formalism is used to project the performance of different combinations of loss-reduction strategies implemented together. Finally, a techno-economic analysis is performed to predict the price points at which the hybrid technologies along the roadmap become competitive with non-hybrid photovoltaic and solar thermal technologies. The most advanced hybrid technology along the roadmap employs an evacuated cavity, a transparent low-emissivity coating, and silicon heterojunction photovoltaic cells.
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•Design of solar air cavity-receiver with RPC absorbers is presented.•5 kW prototype was experimentally tested under concentrated thermal radiation.•Parameters: RPC material, pore ...size, concentration ratio and air mass flow rate.•SiSiC 10 PPI achieved peak efficiency of 0.69 at 1133 °C air outlet temperature.
Concentrated solar energy can be used as the source of high-temperature heat for industrial processes, but the challenge is to design a solar receiver that can effect such a thermal conversion efficiently. This study reports on the engineering design and experimental testing of a 5 kW solar cavity-receiver containing a reticulated porous ceramic (RPC) structure that can absorb high-flux radiation volumetrically and heat up, by convection, an air flow serving as the heat transfer fluid. The thermal performance, characterized by the thermal efficiency and the air outlet temperature, was determined experimentally for four parameters, namely: RPC material (silicon-infused silicon carbide or SiSiC, alumina, and ceria), mean pore size (range 0.8–2.5 mm, corresponding to 10–30 pores per inch or PPI, at 0.90 porosity), solar concentration ratio (range 1965–3900 suns over a 4 cm-diameter cavity aperture, supplied by a high-flux solar simulator), and air mass flow rate (range 2–10 kg/h). Thermal efficiencies between 0.22 and 0.69 were obtained at steady-state air outlet temperatures ranging from 1160 to 450 °C. Larger pores enhance heat transfer while variable porosity across the RPC can reduce temperature gradients and potentially contribute to the design optimization. The highest efficiency of 0.69 was achieved by the SiSiC 10 PPI cavity at an air outlet temperature of 1133 °C and air mass flow rate of 9.9 kg/h. The solar receiver design proved to deliver a high-temperature air flow (>1000 °C) with a reasonably high thermal efficiency (>0.65).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Comprehensive thermo-economic assessments of small-scale solar ORC systems are presented.•Various solar collectors, ORC configurations, expanders and fluids are considered.•Evacuated collectors, ...subcritical recuperated cycle, piston expander, isobutane are preferred.•Highest electricity generation and thermal efficiency are 73 kWh/year/m2 and 5.5%.•Levelised cost and payback as low as 0.35 $/kWh and 16 years in high solar-resource areas.
In this paper, results from comprehensive thermoeconomic assessments of small-scale solar organic Rankine cycle (ORC) systems are presented based on weather data in London, UK, which is taken as representative of a temperate climate with modest temperature changes, mild winters and moderate summers. The assessments consider a range of: (i) solar collector types (flat-plate, evacuated-tube, and evacuated flat-plate collectors); (ii) power cycle configurations (basic/recuperative, partial/full evaporating, and subcritical/transcritical cycles); (iii) expander types (scroll, screw, and piston) and designs; and (iv) a set of suitable working fluids. All possible solar-ORC system designs are optimised by considering simultaneously key parameters in the solar field and in the power cycle in order to obtain the highest electricity generation, from which the best-performing systems are identified. Selected designs are then subjected to detailed, annual simulations considering the systems’ operation, explicitly considering off-design performance under actual varying weather conditions. The results indicate that, among all investigated designs, solar-ORC systems based on the subcritical recuperative ORC (SRORC), evacuated flat-plate collectors (EFPCs), a piston expander, and isobutane as the working fluid outperforms all the other system designs on thermodynamic performance, whilst having the highest annual electricity generation of 1,100 kW·h/year (73 kW·h/year/m2) and an overall thermal efficiency of 5.5%. This system also leads to the best economic performance with a levelised cost of energy (LCOE) of ~1 $/kW·h. Apart from the specific weather data used for these detailed system simulations, this study also proceeds to consider a wider range of climates associated with other global regions by varying the solar resource available to the system. Interestingly, it is found that the optimal solar-ORC system design remains unchanged for different conditions, however, the LCOE can drop below 0.35 $/kW·h and payback times can be shorter than 16 years in high solar-resource regions, even in the absence of incentives that would otherwise lead to even better economic performance. This work complements previous efforts in the literature by considering the full design and operational features of solar-ORC systems, thereby providing valuable guidance for selecting appropriate cycle configurations, components, working fluids and other characteristics and, for the first time, presents a comprehensive comparison of such systems in small-scale applications.
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IMTLJ, KILJ, KISLJ, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
This research developed an effective environmental temperature control system for homes and buildings. The study used a photovoltaic panel (PV) and developed a solar installation with thermosiphon ...circulation, which has a flat solar collector and heat-insulating translucent glass with double glazing with reduced pressure. The coolant is made of thin-walled corrugated stainless pipe. The heat from the solar flux heats the liquid removed from the collector, and cold water from the siphon enters its place. There is a constant circulation of heat, which increases heat transfer efficiency by eliminating additional partitions between the panel and thermal insulation. We have also developed a solar system control controller, which includes an electronic unit with six sensors. The six sensors are controlled by the STM32 programmable Logistics Integrated circuit (FPGA), designed to monitor the entire solar system, and the drives include power relays. The performance of the photovoltaic panel and the room’s temperature change are calculated during both the simulation and testing of the controller. The standard error was 20% compared to other controllers. During the experiment, the consumption savings amounted to about 1% due to the control signal in the controller, which has a significant impact on the service life of the equipment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, electricity and hydrogen production of an integrated system with energy and exergy analyses are investigated. The system also produces clean water for the water electrolysis system. ...The proposed system comprises evacuated tube solar collectors (ETSCs), parabolic trough solar collectors (PTSCs), flash turbine, organic Rankine cycles (ORC), a reverse osmosis unit (RO), a water electrolysis unit (PEM), a greenhouse and a medium temperature level geothermal resource. The surface area of each collector is 500 m2. The thermodynamics analysis of the integrated system is carried out under daily solar radiation for a day in August. The fluid temperature of the medium temperature level geothermal resource is upgraded by ETSCs and PTSCs to operate the flash turbine and the ORCs. The temperature of the geothermal fluid is upgraded from 130 °C to 323.6 °C by the ETSCs and PTSCs. As a result, it is found that the integrated system generates 162 kg clean water, 1215.63 g hydrogen, and total electrical energy of 2111.04 MJ. The maximum energy and exergy efficiencies of the overall system are found as 10.43% and 9.35%, respectively.
•The temperature of the geothermal resource is increased to high-degree by SCs.•The energetic and exergetic performance of the integrated system are found.•The efficiency of the ETSCs and PTSCs is investigated.•Net electricity, the amount of clean water and hydrogen of the system are found.•The effect of daily solar radiation on the performance of system is investigated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A robust transient thermal model for PTC collectors is proposed.•A heuristic optimisation approach is applied to the design of PTC thermal fields.•Single collector optimal dimensions and overall ...network arrangement are defined.•PTC's versatility is evidenced by investigating its applications across a range of low to high temperatures.
This study presents the development of a transient model for designing and optimising parabolic trough solar thermal plants for industrial processes. The model is validated against published experimental data and other models from the literature. A heuristic optimization methodology based on Particle Swarm Optimization (PSO) to maximise the Present Value of the Life Cycle Energy Savings (PVLCES) is employed. This methodology is applied to three case studies. The results highlight the versatility of PTC (parabolic trough collector) technology in handling a wide range of temperatures. Additionally, the study reveals the optimal PTC aperture width dimensions that maximise the capture of solar thermal energy while increasing the solar fraction. Specifically: For low-temperature processes, the optimum aperture width is 5.0 m; in medium-temperature processes, the optimum aperture width increases to 5.5 m; for high-temperature applications, the optimal value is 5.8 m. Finally, the optimised networks achieve the following heat load-to-area ratios: Low-temperature applications: 0.57 kW/m²; medium-temperature applications: 0.58 kW/m²; high-temperature applications: 0.6 kW/m².
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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