Improving efficiency of domestic solar thermal systems by a flow control

Víg, Piroska; Seres, I.; Vladár, P.

doi:10.1016/j.solener.2021.10.028

Cited by 7 publications

(4 citation statements)

References 24 publications

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“…Besides the use of solar energy in industrial areas such as power generation, the use of this energy source in domestic and semi-industrial areas such as cooking, air heaters, and crop dryers should not be neglected. Several studies can be found concerning domestic solar collectors [1][2][3][4]. For example, Nemati and Javanamrdi [1] optimized domestic solar cylindrical-parabolic cookers using exergy analysis.…”

Section: Introduction 1introductionmentioning

confidence: 99%

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

Nemati

2024

Energies

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In this paper, a novel tubular solar air heater is introduced. In this air heater, the hot boundary layer is drawn into the absorber tube and can provide thermal energy at moderate temperatures. Several different cases were simulated and a correlation was proposed to predict the collector’s effectiveness as a function Rayleigh number and Reynolds number. An equation was derived to find the effectiveness of this collector. Finally, a real case was studied with non-uniform solar flux distribution, as well as radiation heat loss. Good agreement was found between the results and those derived by the proposed analytical method. For different suction values, the first-law and the second-law efficiencies were calculated. Based on the exergy analysis, exergy destruction in absorption is the dominant factor that is unavoidable in low-temperature collectors. It was shown that there is an optimum suction value at which the second-law efficiency is maximized. At the optimum point, temperature rise can reach 54 K, which is hardly possible with a flat plate collector. Based on the exergy analysis, the relation between tube wall temperature and air outlet temperature in their dimensionless forms at the optimum working condition was derived, and it was shown that effectiveness at the optimum working condition is around 0.5. This means that the air temperature rise shall be half of the temperature difference between collector wall and the ambient temperatures. A high outlet temperature besides the low cost of construction and maintenance are the main advantages of this air heater. With such a high temperature rise, this type of collector can increase the use of solar energy in domestic applications.

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Section: Introduction 1introductionmentioning

confidence: 99%

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

Nemati

2024

Energies

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“…The study also demonstrated that the TRNSYS simulation software is a reliable tool for determining the thermal performance of SHW systems. Vig et al [12] studied a variable flow vacuum tube solar thermal collector system. Their research demonstrated that the variable flow SHW system collected more energy compared to the constant flow one.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Energy, Economic and Environmental Performance of Solar Water Heaters for Domestic Hot Water Supply in Northern European Climate

Parthiban

Cotter

McCloskey

2023

36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 20

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A significant portion of energy expense of a residential household goes toward the provision of domestic hot water (DHW) ~19%. The use of solar thermal water heating provides a local way to offset this energy requirement with a renewable resource. Solar thermal water heating systems are commonly used in hot climates from Southern Europe to the Equator however in the past they were seen as not so economically viable in colder climates. The solar collector that is readily available on the market for DHW generation is the standard flat plate collector (SFPC), but they are not attractive for use in higher latitudes due to low operating temperature and high heat loss. Although convection suppression has been identified as a method to improve the performance of flat plate collector it has not yet achieved mainstream commercialisation. In this work we attempt to show that the conventional flat plate collector still has potential in higher latitude when modified to suppress convection heat loss. The modified FPC that is particularly of focus in this work is the one with honeycomb transparent insulation (MFPC). We compare the performance of SFPC and MFPC in colder climate considering different auxiliary heating options such as electricity, gas, and oil, at their recent energy prices. Using TRNSYS software, we modelled the annual energy generated by these collectors using a typical domestic load case and found that SFPC produced 1446.60 kWh/year while MFPC produced 1993.50 kWh/year. For a typical household with a daily hot water consumption of 200 L, SFPC requires 3858.69 kWh/year of auxiliary energy while MFPC requires 3458.24 kWh/year. The economic analysis shows that the MFPC with electrical heating is the highly viable option with a Net Present Value (NPV) of € 5078.95. The CO2 emission reduction from the SFPC and MFPC with electrical auxiliary heating are 39.54 kgCO2/year and 79.58 kgCO2/year, respectively, compared to conventional electrical immersion heaters.

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“…Flatplate collector, evacuated glass tube collector, parabolic trough collector, linear Fresnel reflector, and compound parabolic collector are used for 45 to 400 °C whereas point and line type solar collectors such as solar tower and parabolic dish are used for 1000 to 1500 °C temperature [17,18]. Flow control by optimum TRNSYS model may enhance effective efficiency up to 7% or more [19]. TRNSYS home models have demonstrated 37% to 68% solar fractions under diverse weather conditions [20].…”

Section: Introductionmentioning

confidence: 99%

“…Because of its excellent thermal efficiency and good performance in adverse weather condition especially in subzero temperature areas [29], evacuated tube collectors have received a lot of attention. Recent trends include use of nanofluids [30][31][32][33], enhancement of heat pipe performance, use of latent heat storage [34], molten salts [35], heat loss reduction designs/insulations [36], geometric heat pipes [37,38], flow control and design [19,[39][40][41], and proposing holistic architectures such as CCHP [42][43][44]. The existing literature emphasizes on individual detailed energy, exergy, and economic studies but lacks a comparative performance of various technologies.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Thermal Performance Assessment of Various Solar Collectors for Domestic Water Heating

Kalair

Seyedmahmoudian

Saleem

et al. 2022

International Journal of Photoenergy

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Growing population, depleting fossil fuels, economic expansions, and energy intensive life style demand are resulting in higher energy prices. We use energy as of heat and electricity, which can directly be obtained from sun using thermal collectors and solar cells. Solar thermal systems are gaining attention for water and space heating applications due to green aspects of solar energy. A solar thermal collector is a vital part of solar thermal energy system to absorb radiant energy from the sun. In this study, a solar water heating (SWH) system has been designed and simulated in the TRNSYS ® software using thermal and chemical properties of heat transfer fluids using REFPROP for dwellings located on ±31° latitudes (+31 Lahore in Pakistan and -31° Perth in Australia). We present an efficiency parametric optimization-based model for water and space heating. Simulation results for four types of solar thermal collectors are presented, and performance is analyzed on the basis of output temperature ( T out ), solar fraction ( f ), and collector efficiency ( η ). This study evaluates the comparative performance of evacuated tube collector (ETC), flat-plate collector (FPC), compound parabolic concentrator (CPC), and thermosiphon-driven systems. Our findings conclude the evacuated glass tube collector achieves the highest solar fraction, i.e., 50% of demand coverage during August in Pakistan and February in Australia, with an overall average of 43% annually.

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Improving efficiency of domestic solar thermal systems by a flow control

Cited by 7 publications

References 24 publications

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

Design, Simulation and Optimization of a Novel Transpired Tubular Solar Air Heater

Analysis of Energy, Economic and Environmental Performance of Solar Water Heaters for Domestic Hot Water Supply in Northern European Climate

A Comparative Thermal Performance Assessment of Various Solar Collectors for Domestic Water Heating

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