Review of materials for solar thermal collectors

Alghoul, M. A.; Sulaiman, Muhammad Azwadi; Azmi, B. Z.; Wahab, Mahdi Abd.

doi:10.1108/00035590510603210

Cited by 72 publications

(32 citation statements)

References 45 publications

(43 reference statements)

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“…It is therefore important to ensure adequate insulation of the thermal solar system (Deutsches, 2005). Thermal insulation must be weather resistant, fireproof, durable and dimensionally stable (Alghoul et al, 2005). Koyuncu (2006) suggest the use of hardwood as collector frame construction which is also used as insulator.…”

Section: Thermal Insulationmentioning

confidence: 99%

Experimental analysis of air flow patterns in perfomance of flat plate solar collectors

Ramadhani¹,

Minja²,

Njau³

2015

Afr. J. Agric. Res.

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Solar drying is one of the promising methods of reducing post-harvest losses in rural areas. Studies have shown that, heat transfer mechanisms in a solar collector influences the performance of solar dryers. This study aims at improving heat transfer in flat plate solar collectors by designing different air flow patterns inside the collector. Three flat plate solar collectors were constructed by using Pterocarpus timber (Mninga) and tested for their effect in heat transfer at various flow patterns. Three different flow patterns namely: single duct front pass, double duct parallel flow and double duct counter flow were designed and tested. Experimental results show that collector efficiency of single duct front pass, double duct front pass and double duct counter flow were 30.6, 36.1 and 38.2% respectively. It was found that, double duct flow gives improved performance compared to single duct flow due to the increased heat transfer area. In additional, double duct counter flow showed superior performance compared to double duct parallel flow due to extended heat transfer area and the advantage of air preheating at the inlet which reduces heat losses through glazing. Through this study, it was concluded that, solar collector designs with double duct counter flow can improve collector performance for up to 8.3% compared to single duct front pass.

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Section: Thermal Insulationmentioning

confidence: 99%

Experimental analysis of air flow patterns in perfomance of flat plate solar collectors

Ramadhani¹,

Minja²,

Njau³

2015

Afr. J. Agric. Res.

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“…Condensation and moisture can also cause their deterioration, resulting in reduced performance and eventual system failure. ETCs have the advantage that their vacuum envelope reduces convection and conduction losses [5]; they can, therefore, perform even in cold weather when FPCs perform poorly due to heat losses [6]. ETCs also show better performance…”

Section: Introductionmentioning

confidence: 99%

Profitability Variations of a Solar System with an Evacuated Tube Collector According to Schedules and Frequency of Hot Water Demand

et al. 2016

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Abstract:The use of solar water heating systems with evacuated tube collectors has been experiencing a rapid growth in recent years. Times when there is demand for hot water, the days of use and the volumes demanded may determine the profitability of these systems, even within the same city. Therefore, this paper characterizes the behavior of a solar system with active circulation with the objective of determining the profitability variations according to the timing and schedule of demand. Through a simplified methodology based on regression equations, calculated for each hour of the day based on data from an experimental facility, the useful energy is estimated from the time and frequency of the demand for hot water at 60 • C. The analysis of the potential profitability of the system in more than 1000 scenarios analyzed shows huge differences depending on the number of days when the water is demanded, the time when demand occurs, the irradiation and the average price of energy. In cities with high irradiation and high energy prices, the system could be profitable even in homes where it is used only on weekends. The study of profitability in a building of 10 homes shows that by applying an average European household's profile for hot water demand, levels close to full potential would be reached; for this, it is necessary to optimize the collection surface.

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“…The thermal conductivity of traditional thermal insulation materials like mineral wool, expanded polystyrene (EPS), and extruded polystyrene (XPS) is in the range of 0.033 W/mK to 0.040 W/mK, while polyurethane (PUR) has thermal conductivity ranging from 0.020 W/mK to 0.030 W/mK [1][2][3]. To achieve very low thermal transmittance, U-value (rate of heat transfer, in watts, across one square meter area divided by the temperature gradient across the surface), high insulation thickness in the range of 40 cm to 50 cm is required [3].…”

Section: Introductionmentioning

confidence: 99%

Small-Scale Flat Plate Collectors for Solar Thermal Scavenging in Low Conductivity Environments

Ogbonnaya

Weiss

2017

International Journal of Photoenergy

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There is great opportunity to develop power supplies for autonomous application on the small scale. For example, remote environmental sensors may be powered through the harvesting of ambient thermal energy and heating of a thermoelectric generator. This work investigates a small-scale (centimeters) solar thermal collector designed for this application. The absorber is coated with a unique selective coating and then studied in a low pressure environment to increase performance. A numerical model that is used to predict the performance of the collector plate is developed. This is validated based on benchtop testing of a fabricated collector plate in a low-pressure enclosure. Model results indicate that simulated solar input of about 800 W/m 2 results in a collector plate temperature of 298 K in ambient conditions and up to 388 K in vacuum. The model also predicts the various losses in W/m 2 K from the plate to the surroundings. Plate temperature is validated through the experimental work showing that the model is useful to the future design of these small-scale solar thermal energy collectors.

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Review of materials for solar thermal collectors

Cited by 72 publications

References 45 publications

Experimental analysis of air flow patterns in perfomance of flat plate solar collectors

Experimental analysis of air flow patterns in perfomance of flat plate solar collectors

Profitability Variations of a Solar System with an Evacuated Tube Collector According to Schedules and Frequency of Hot Water Demand

Small-Scale Flat Plate Collectors for Solar Thermal Scavenging in Low Conductivity Environments

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