scholarly journals Optimizing Large-Scale Solar Field Efficiency: Latvia Case Study

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4171
Author(s):  
Ilze Polikarpova ◽  
Roberts Kakis ◽  
Ieva Pakere ◽  
Dagnija Blumberga
Keyword(s):  
Solar Energy ◽  
Influencing Factors ◽  
Heat Carrier ◽  
Thermal Energy ◽  
Solar Collector ◽  
Energy Production ◽  
Large Scale ◽  
District Heating ◽  
Field Efficiency ◽  
Solar Field

Solar energy transformation technologies are increasingly being used worldwide in the district heating sector. In the Baltic states, only one district heating company has implemented a large-scale solar collector field into its thermal energy production system, which is analyzed within this research. In this study, we analyzed the first year operation of the solar field, solar collector efficiency, and several influencing factors, i.e., ambient air temperature, heat carrier flow, and the temperature difference between the supply and return heat carrier temperatures. The study includes collecting and compilation of the data, analyzing influencing factors, and data analysis using the statistical analysis method. In addition, the research presents a simplified multi-regression model based on the actual performance of a large-scale solar field, which allows for forecasting the efficiency of solar collectors by taking into account the main operational parameters of the DH system. The results show that solar energy covers around 90% of the summer heat load of a particular district heating system. However, they also show room for improvements in producing all the necessary heat in the summer using solar energy. The regression analyses show that the most significant correlation between all parameters examined was obtained in May, reaching R2 = 0.9346 in solar field efficiency evaluation. This is due to several suitable conditions for solar energy production, i.e., placing solar collectors at an angle for them to be the most productive, having enough space in the storage tank, and the demand for thermal energy being still higher than in the summer months.

Is It Possible to Obtain More Energy from Solar DH Field? Interpretation of Solar DH System Data

2021 ◽  
Vol 25 (1) ◽  
pp. 1284-1292
Author(s):  
Roberts Kaķis ◽  
Ilze Poļikarpova ◽  
Ieva Pakere ◽  
Dagnija Blumberga
Keyword(s):  
Air Temperature ◽  
Solar Collector ◽  
Large Scale ◽  
District Heating ◽  
Ambient Air ◽  
Energy Sector ◽  
Climatic Conditions ◽  
Water Tank ◽  
System Productivity ◽  
Ambient Air Temperature

Abstract Europe has a course to zero emissions by 2050, with a strong emphasis on energy sector. Due to climatic conditions in Latvia, district heating (DH) plays an important role in the energy sector. One of the solutions to achieve the set goals in DH is to introduce emission-free technology. Therefore, the popularity of installation of large-scale solar collector plants continues to increase in DH in Europe. The first large-scale solar collector field in the Baltic States was installed in 2019. Solar collector active area is 21 672 m2 with heat storage water tank 8000 m3. The article shows the first operation results of this system and evaluates influencing factors. The results of the analysis show that system productivity is mainly demanded by solar radiation, and the strongest correlation between these parameters were established in May. The highest correlation between ambient air temperature and produced thermal energy is reached when ambient air temperature is between 7 °C to 15 °C and production process has not been externally regulated. The temperature difference between flow and return temperatures of the heat carrier affect solar collector performance minimally and strong correlation was not observed.

Designing a novel solar-assisted heat pump system with modification of a thermal energy storage unit

2019 ◽  
Vol 233 (5) ◽  
pp. 588-603 ◽  
Author(s):  
Mustafa Aktaş ◽  
Meltem Koşan ◽  
Erhan Arslan ◽  
Azim Doğuş Tuncer
Keyword(s):  
Energy Storage ◽  
Solar Energy ◽  
Heat Pump ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Collector ◽  
Working Fluid ◽  
Storage Unit ◽  
Heating Systems ◽  
Energy Storage Unit

The integrated usage of solar energy systems, heat pump applications, and thermal energy storage units is an effective way for heating systems due to their sustainability and stability in operations. In this study, a novel direct solar-assisted heat pump with thermal energy system has been designed which uses the solar collector as the evaporator of the heat pump. Besides, two-dimensional transient numeric analyses have been conducted for the thermal energy storage unit using the ANSYS Fluent 16.2 commercial software package. With this direct system, the heat required for heating systems is supplied from the condenser with the heat received from the solar collector of the working fluid. For an effective and high performance system, the solar collector is designed as a double-pass which provided superheating of the working fluid. It is aimed to store the surplus energy from the solar energy in the thermal energy storage unit and to operate the system continuously and efficiently in both sunny and overcast weather conditions. Furthermore, the system has been analyzed theoretically and the results show that coefficient of performance may improve. As a result, this newly designed system can be successfully applied for thermal applications.

Solar Field Efficiency and Electricity Generation Estimations for a Hybrid Solar Gas Turbine Project in France

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Pierre Garcia ◽  
Alain Ferriere ◽  
Gilles Flamant ◽  
Philippe Costerg ◽  
Robert Soler ◽  
...  
Keyword(s):  
Solar Energy ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Electricity Generation ◽  
Field Efficiency ◽  
Solar Receiver ◽  
Solar Field ◽  
External Combustion

The production of electricity with gas turbine and solar energy project aims to install at the Themis site (Targasonne, France) a prototype of hybrid solar/fossil gas-turbine system for electricity generation. The system features a 3800kWth pressurized air solar receiver combined with a fossil backup feeding a recuperated 1400kWe Turbomeca gas turbine with an external combustion chamber.

System and component modelling of a low temperature solar thermal energy conversion cycle

2013 ◽  
Vol 24 (4) ◽  
pp. 51-62
Author(s):  
Shadreck M. Situmbeko ◽  
Freddie L. Inambao
Keyword(s):  
Low Temperature ◽  
Solar Energy ◽  
Thermal Energy ◽  
Electrical Power ◽  
Solar Thermal ◽  
Working Fluid ◽  
Small Scale ◽  
Solar Thermal Energy ◽  
Solar Field ◽  
Conversion Technology

Solar thermal energy (STE) technology refers to the conversion of solar energy to readily usable energy forms. The most important component of a STE technology is the collectors; these absorb the shorter wavelength solar energy (400-700nm) and convert it into usable, longer wavelength (about 10 times as long) heat energy. Depending on the quality (temperature and intensity) of the resulting thermal energy, further conversions to other energy forms such as electrical power may follow. Currently some high temperature STE technologies for electricity production have attained technical maturity; technologies such as parabolic dish (commercially available), parabolic trough and power tower are only hindered by unfavourable market factors including high maintenance and operating costs. Low temperature STEs have so far been restricted to water and space heating; however, owing to their lower running costs and almost maintenance free operation, although operating at lower efficiencies, may hold a key to future wider usage of solar energy. Low temperature STE conversion technology typically uses flat plate and low concentrating collectors such as parabolic troughs to harness solar energy for conversion to mechanical and/or electrical energy. These collector systems are relatively cheaper, simpler in construction and easier to operate due to the absence of complex solar tracking equipment. Low temperature STEs operate within temperatures ranges below 300oC. This research work is geared towards developing feasible low temperature STE conversion technology for electrical power generation. Preliminary small-scale concept plants have been designed at 500Wp and 10KWp. Mathematical models of the plant systems have been developed and simulated on the EES (Engineering Equation Solver) platform. Fourteen candidate working fluids and three cycle configurations have been analysed with the models. The analyses included a logic model selector through which an optimal conversion cycle configuration and working fluid mix was established. This was followed by detailed plant component modelling; the detailed component model for the solar field was completed and was based on 2-dimensional segmented thermal network, heat transfer and thermo fluid dynamics analyses. Input data such as solar insolation, ambient temperature and wind speed were obtained from the national meteorology databases. Detailed models of the other cycle components are to follow in next stage of the research. This paper presents findings of the system and solar field component.

Considerations for the Design of Solar-Thermal Chemical Processes

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Janna Martinek ◽  
Melinda Channel ◽  
Allan Lewandowski ◽  
Alan W. Weimer
Keyword(s):  
Solar Energy ◽  
Water Splitting ◽  
Thermal Reduction ◽  
Absorption Efficiency ◽  
Chemical Processes ◽  
Solar Thermal ◽  
System Efficiency ◽  
Field Efficiency ◽  
Definition Of ◽  
Solar Field

A methodology is presented for the design of solar thermal chemical processes. The solar receiver efficiency for the high temperature step, defined herein as the ratio of the enthalpy change resulting from the process occurring in the receiver to the solar energy input, is limited by the solar energy absorption efficiency. When using this definition of receiver efficiency, both the optimal reactor temperature for a given solar concentration ratio and the solar concentration required to achieve a given temperature and efficiency shift to lower values than those dictated by the Carnot limitation on the system efficiency for the conversion of heat to work. Process and solar field design considerations were investigated for ZnO and NiFe2O4 “ferrite” spinel water splitting cycles with concentration ratios of roughly 2000, 4000, and 8000 suns to assess the implications of using reduced solar concentration. Solar field design and determination of field efficiency were accomplished using ray trace modeling of the optical components. Annual solar efficiency increased while heliostat area decreased with increasing concentration due to shading and blocking effects. The heliostat fields designed using system efficiency for the conversion of heat to work were found to be overdesigned by up to 21% compared with those designed using the receiver efficiency alone. Overall efficiencies of 13–20% were determined for a “ferrite” based water splitting process with thermal reduction conversions in the range of 35–100%.

Performance Evaluation of an Asymmetric Hybrid Solar Collector: Effect of Nanofluids on the Electrical and Thermal Energy Production

2016 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki ◽  
A. S. Kontos
Keyword(s):  
Performance Evaluation ◽  
Thermal Energy ◽  
Solar Collector ◽  
Energy Production ◽  
Calculated Data ◽  
Electrical Energy ◽  
Hot Water ◽  
Cell Efficiency ◽  
Asymmetric Hybrid ◽  
The Mediterranean

The scope of this work is the analysis of the electrical and thermal performance of an asymmetric hybrid solar collector PVT and the prospect of the installation of a system consisting of these collectors in the Mediterranean region. For the purpose of this work, the Solarus V11 PVT collector (readily available in our laboratory) was chosen and numerically modeled. The main asset of this collector is its asymmetric reflector that consists of a circular and a parabolic part leading to a maximum thermal energy production even in winter as the solar radiation is concentrated in the edge of the reflector rather than in the center of it. Using a software developed in Matlab, the calculated data are presented for both thermal and electrical energy and they are compared with the hot water and electrical energy requirements (per month) around the Mediterranean territory. Furthermore, a parametric study is conducted in order to investigate the effect of the mass flow rate and the PVT array configuration on the thermal and electrical production, as well as the efficiency of the solar cells of the system. Moreover, in order to increase the PV cell efficiency, nanofluids, i.e. mixtures of nanometer size particles well-dispersed in a base fluid, are proposed as heat transfer fluids and the analysis for the performance evaluation is conducted for different nanoparticle loadings.

scholarly journals Online Forecasting of the Solar Energy Production

2018 ◽  
Vol 60 (1) ◽  
pp. 104-110
Author(s):  
Marius Paulescu ◽  
Nicoleta Stefu ◽  
Ciprian Dughir ◽  
Robert Blaga ◽  
Andreea Sabadus ◽  
...  
Keyword(s):  
Solar Energy ◽  
Energy Production ◽  
Large Scale ◽  
Research Progress ◽  
The West ◽  
Electricity Grid ◽  
Large Scale Integration ◽  
Experimental Facilities ◽  
Scale Integration ◽  
Photovoltaic Plants

AbstractForecasting the solar energy production is a key issue in the large-scale integration of the photovoltaic plants into the existing electricity grid. This paper reports on the research progress in forecasting the solar energy production at the West University of Timisoara, Romania. Firstly, the experimental facilities commissioned on the Solar Platform for testing the forecasting models are briefly described. Secondly, a new tool for the online forecasting of the solar energy production is introduced. Preliminary tests show that the implemented procedure is a successful trade-off between simplicity and accuracy.

Review on Solar Collector for Agricultural Produce

2018 ◽  
Vol 9 (1) ◽  
pp. 414 ◽  
Author(s):  
Ahmad Fudholi ◽  
Kamaruzzaman Sopian
Keyword(s):  
Solar Energy ◽  
Thermal Energy ◽  
Solar Collector ◽  
Energy Systems ◽  
Exergy Efficiency ◽  
Solar Collectors ◽  
Agricultural Produce ◽  
Essential Components ◽  
Energy And Exergy ◽  
Solar Air Collector

<span>Among the most important components of solar energy systems, solar collectors are devices that receive solar energy and convert it into thermal energy, as most essential components of solar dryer. This review presents description and previous work performed on performances of solar air collector for agricultural produce. In addition, various solar collectors are classified and described. Solar air collectors for drying application of agricultural produce are presented and summarize. The energy and exergy efficiency of the solar air collector ranges from 28% to 62% and from 30% to 57%, respectively. </span>

scholarly journals Design Aspects for Large-scale Pit and Aquifer Thermal Energy Storage for District Heating and Cooling

2018 ◽  
Vol 149 ◽  
pp. 585-594 ◽  
Author(s):  
Thomas Schmidt ◽  
Thomas Pauschinger ◽  
Per Alex Sørensen ◽  
Aart Snijders ◽  
Reda Djebbar ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Large Scale ◽  
District Heating ◽  
Heating And Cooling ◽  
Aquifer Thermal Energy Storage
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