Steady state operation exergy‐based optimization for solar thermal collectors

Grosu, Lavinia; Mathieu, Antoine; Rochelle, P.; Feidt, Michel; Ahmadi, Mohammad Hossein; Sadeghzadeh, Milad

doi:10.1002/ep.13359

Cited by 20 publications

(10 citation statements)

References 38 publications

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“…The solar energy intercepted by the collector is calculated from

{\dot{Q}}_{collector} = italicAG,

where A and G are solar collector area and solar radiation intensity per unit of collector area (W/m 2 ), respectively. The energy absorbed by the collector is calculated using

{\dot{Q}}_{i} = ζ {\dot{Q}}_{collector},

where ζ is the solar collector efficiency calculated by

ζ = ζ_{o} - \frac{a_{1} ∆ T}{G} - \frac{a_{2} {∆ T}^{2}}{G},

where the constants ζ o , a 1 , and a 2 are given by the CPC manufacturer. ∆T is the temperature difference between the hot engine cylinder and ambient temperature.…”

Section: Methodsmentioning

confidence: 92%

“…The CPC can achieve moderate temperatures up to 200°C and presents a good compromise between simplicity and thermal performance . Grosu et al showed by exergy analysis that CPC is a high‐performance collector and can technically and economically achieve temperatures as high as 180°C. However, to the best of the authors knowledge, no Stirling engine has been directly coupled to the CPC.…”

Section: Introductionmentioning

confidence: 99%

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A new duplex Stirling engine concept for solar‐powered cooling

Daoud

Friedrich

2020

Int J Energy Res

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The global cooling demand is one of the fastest growing energy demands and is putting a strain on the electricity infrastructure. Solar-powered cooling could provide most of the cooling demand due to the coincidence of the cooling demand and the solar irradiance. In particular, the solar-powered Stirling-cycle cooler has low maintenance requirement, high theoretical efficiency, and use of environmentally friendly gases. However, Stirling-cycle coolers are expensive due to high driving temperatures, complex heat exchangers, and expensive solar tracking so that they have so far only been successful at high-temperature difference applications. This study introduces a novel directly coupled solar Stirling cooler for which the hot engine cylinders are deployed inside evacuated tube collectors. The machine uses air as working fluid, and its driving mechanism is based on the free-piston, balanced compound technology that was patented by Finkelstein. A second-order mathematical model is used to investigate the performance of the machine for different cylinder arrangements, gas leakage rates, chilling temperatures, and solar irradiance. In addition, the regenerators are optimised to maximise the cold production. It is shown that mechanical frictions can be reduced to 20% by selecting an appropriate cylinder arrangement. The solar cooler achieves a maximum cold production rate of 367.5 W/m 2 without using external heat exchangers at load temperature of 7 C, which is comparable with photovoltaic powered coolers.In addition, the machine is relatively simple, has safe and quiet operation, uses ambient air as working gas, and is able to produce a wide range of chilling including sub-zero temperatures without changing the working gas. The direct thermal coupling of the Stirling cooler to evacuated tube collectors significantly reduces the complexity of the machine and removes intermediate heat transfer steps which reduce the performance. Thus, the suggested cooling technology has great potential for solar refrigeration, especially for low power and near ambient cooling.

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“…The solar energy intercepted by the collector is calculated from

{\dot{Q}}_{collector} = italicAG,

where A and G are solar collector area and solar radiation intensity per unit of collector area (W/m 2 ), respectively. The energy absorbed by the collector is calculated using

{\dot{Q}}_{i} = ζ {\dot{Q}}_{collector},

where ζ is the solar collector efficiency calculated by

ζ = ζ_{o} - \frac{a_{1} ∆ T}{G} - \frac{a_{2} {∆ T}^{2}}{G},

where the constants ζ o , a 1 , and a 2 are given by the CPC manufacturer. ∆T is the temperature difference between the hot engine cylinder and ambient temperature.…”

Section: Methodsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

A new duplex Stirling engine concept for solar‐powered cooling

Daoud

Friedrich

2020

Int J Energy Res

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“…The primary use of a solar collector is the collection of solar energy and the transfer of heat to a fluid. This heat can then be removed from the fluid via a heat exchanger 7 . Electricity will be produced from this heat, using a heating engine, without damaging the environment.…”

Section: Introductionmentioning

confidence: 99%

“…This heat can then be removed from the fluid via a heat exchanger. 7 Electricity will be produced from this heat, using a heating engine, without damaging the environment. The main factor affecting the system is the transfer of heat.…”

Section: Introductionmentioning

confidence: 99%

Energy and exergy analysis for stationary solar collectors using nanofluids: A review

Eltaweel

Abdel‐Rehim

2020

Int J Energy Res

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Summary Fossil fuels demonstrate pollution effects and significant emissions on the atmosphere, which made the use of clean, renewable sources of energy a necessity. Renewable energy has many sources, but the most promising and cheapest energy source is solar energy, which has led to a focus on efficient solar energy harvesting to be cheaper for public use. Stationary solar collectors like evacuated tube and flat‐plate solar collectors are the most commonly used solar collectors for their simplicity of installation and maintenance. They are mostly used for domestic applications such as solar water heaters. Nanofluids can improve the thermal properties of the working fluid which can improve the performance of a collector. This review paper discussed the effect of different parameters on the stationary solar collector's performance, such as nanoparticle use, nanoparticle size, concentration, and the base fluid of the nanofluid. This review paper also aims to summarize previous studies performed on the use of different nanofluids on the two types of circulation that can be either thermosiphon or forced circulation for both collectors to investigate the energetic and exergetic efficiencies. The theoretical performance analysis equations of stationary solar collectors are provided too. From the reviewed results, it was concluded that a substantial improvement in both the energetic and exergetic efficiencies of both collectors had been obtained from the use of carbon‐based nanofluids compared to a significant number of different nanofluids. The paper also discusses the significant challenges of nanofluid use and how to overcome them in stationary solar collectors.

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“…For this reason, optimization of the component parameters is highly essential and it involves time consumption and costlier experimentation, respectively. To overcome the above‐said difficulties in the optimization of the SWH units, various computational software and methods are developed to compute the effect of different performance parameters on the long‐term performance of the SWH system 6 …”

Section: Introductionmentioning

confidence: 99%

Optimization of a solar water heating system for vapor absorption refrigeration system

Christopher

Santosh

Vikram

et al. 2020

Env Prog and Sustain Energy

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In this work, the optimization study of the solar collector integrated, with a thermal energy storage tank for the vapor absorption refrigeration system, was studied using TRNSYS. The performance of the integrated system was evaluated considering major contributing parameters such as solar collector area, the mass flow rate of the operating fluids, storage tank volume and height, absorber plate thickness, tube spacing, absorber tube diameter, insulation thickness, and glass thickness/properties, respectively. A physical model of the complete solar water heating (SWH) and refrigeration system was developed followed by simulation studies of the major components for optimization, and finally, the obtained results were compared with the reported data for validation. The results indicated that, by using the solar power with a serpentine tube type flat plate collector of area 24 m2 and a storage volume to a specific collector area of about 60 Lm−2, the optimized system could meet 65% of the annual thermal energy requirement for the refrigeration unit. Further, the annual performance of the optimized solar collector in terms of collector efficiency, heat removal factor, and overall heat loss coefficient was found to be about 0.32, 0.87, and 2.99 W m−2 K, respectively. In addition, the optimization approach that is adopted using TRNSYS in the present study could be used for optimizing the solar‐based energy system for various applications.

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Steady state operation exergy‐based optimization for solar thermal collectors

Cited by 20 publications

References 38 publications

A new duplex Stirling engine concept for solar‐powered cooling

A new duplex Stirling engine concept for solar‐powered cooling

Energy and exergy analysis for stationary solar collectors using nanofluids: A review

Optimization of a solar water heating system for vapor absorption refrigeration system

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