Mathematical modelling of unglazed solar collectors under extreme operating conditions

Bunea, Mircea; Perers, Bengt; Eicher, Sara; Hildbrand, Catherine; Bony, Jacques; Citherlet, S.

doi:10.1016/j.solener.2015.06.012

Cited by 13 publications

(3 citation statements)

References 7 publications

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“…With uncovered solar collectors and required water temperature in the swimming pool at the range of 25 • C, the use of a swimming pool in warm climates (annual global irradiation on horizontal level higher than 1600 kWh/m 2 ) can be extended from April to October. Empirically, the total required solar collectors' area is equal to 80% of the heated swimming pool's free surface [4][5][6].…”

Section: Solar Radiation For Thermal Energy Productionmentioning

confidence: 99%

Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

Katsaprakakis

Zidianakis

2019

Energies

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This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the solar collectors. An automation system is also designed and proposed for the realization of the newly introduced algorithm. The solar-combi system is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m2 of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available solar radiation in the specific area, the proposed solar-combi system can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWhth.

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Section: Solar Radiation For Thermal Energy Productionmentioning

confidence: 99%

Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

Katsaprakakis

Zidianakis

2019

Energies

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“…Non-conventional sources of energy are broadly used in a variety of sectors such as domestic and commercial buildings for space heating and hot water generation [1,2]. Uncovered solar collectors are mainly used to heat swimming pools in summer [3][4][5]. Katsaprakkis et al [6] used solar-combi systems to meet the thermal energy needs for hot water production and swimming pool heating.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Studies on Solar Parabolic trough Collector Using Corrugated Tube Receiver with Conical Strip Inserts

et al. 2022

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The heat transfer characteristics of the working fluid passing through the absorber of a solar parabolic trough collector (SPTC) can be enhanced by the creation of a turbulence effect. Therefore, a novel idea was implemented by introducing a corrugated tube (CT) absorber instead of a plain tube absorber in a solar parabolic trough collector. The heat transfer enhancement was improved further through the use of conical strip inserts inside the corrugated tube absorber of the SPTC. A corrugated tube (CT) receiver with a pitch of 8 mm and corrugation height of 2 mm was used with three different pitches of conical strip inserts (pitch pi = 20 mm, 30 mm and 50 mm) for the analysis of the thermal performance of the SPTC. Initially, experiments were conducted in a plain tube and corrugated tube receiver at different mass flow rates. The convective heat transfer rate was increased for all the configurations of the conical strip inserts. The SPTC performance was good for the combination of the corrugated tube (pc = 8 mm and hc = 2 mm) and the conical strip insert I3 (pi= 20 mm). The experimental results showed that the maximum achieved Nu value, friction factor, instantaneous efficiency and thermal efficiency of the CT-I3 were 177%, 38%, 26.92% and 9% compared to the plain tube under the same working conditions.

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“…As a typical component of passive solar air heating, solar air collectors are mainly used to convert incident solar radiation into useful heat in different types of buildings. These heat collectors have been adopted around the world to reduce fossil fuel consumption for space heating and domestic hot water production [2]. Along these years, several types of solar air collectors, differentiated by the type of solar absorber element (flat plate, V-corrugated plate, cylindrical tubes, plates with fins, etc.)…”

Section: Introductionmentioning

confidence: 99%

Thermal Characteristics and Parametric Analysis of an Improved Solar Wall

Zhao

Zhu

et al. 2021

Applied Sciences

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Solar air collectors installed on buildings can significantly reduce conventional energy consumption in winter and summer. However, some problems arise in the utilization process, such as overheating, inconvenient operation control and low energy efficiency, etc. This work is a parametric analysis focusing on the automatic control and thermal efficiency improvement of the solar wall. An improved color-changing solar wall integrated with automatic control components, such as a photoelectric fan and temperature-controlled damper, was proposed in this paper. Based on the experimental data, the average daily heat output of the color-changing solar wall is 1.08 MJ per unit floor area on clear days in winter and the average thermal efficiency is 56.8%. Meanwhile, a quantitative analysis was carried out based on monitoring experiments for evaluating the thermal characteristic of automatic control components. Furthermore, in order to improve the thermal performance of the solar wall, parametric analysis was performed by numerical simulation. Results from this paper can provide a theoretical basis for the application of solar air collectors in modern buildings.

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Mathematical modelling of unglazed solar collectors under extreme operating conditions

Cited by 13 publications

References 7 publications

Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

Optimized Dimensioning and Operation Automation for a Solar-Combi System for Indoor Space Heating. A Case Study for a School Building in Crete

Heat Transfer Studies on Solar Parabolic trough Collector Using Corrugated Tube Receiver with Conical Strip Inserts

Thermal Characteristics and Parametric Analysis of an Improved Solar Wall

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