Exergy analysis on solar thermal systems: A better understanding of their sustainability

Kalogirou, Soteris A.; Karellas, Sotiriοs; Badescu, Viorel; Braimakis, Konstantinos

doi:10.1016/j.renene.2015.05.037

Cited by 163 publications

(34 citation statements)

References 55 publications

(28 reference statements)

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“…As far as the authors are aware there have been few, if any, in depth research on exergy analysis of evacuated tube collectors and most of the previous works focused on flat plate collectors [12,13], solar air collector [14], and all glass evacuated solar collector [15]. As mentioned by Kalogirou, et al [16] evacuated tube solar collectors treated less often from an exergy view point. Due to lack of sufficient research, using exergy and 2 nd law concept in thermal analysis of heat pipe evacuated collectors, a comprehensive model for these collectors is presented in this work.…”

Section: Introductionmentioning

confidence: 99%

Energy and exergy efficiency of heat pipe evacuated tube solar collectors

2016

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In this paper, a heat pipe evacuated tube solar collector has been investigated both theoretically and experimentally. A detailed theoretical method for energy and exergy analysis of the collector is provided. The method is also evaluated by experiments. The results showed a good agreement between the experiment and theory. Using the theoretical model, the effect of different parameters on the collector's energy and exergy efficiency has been investigated. It is concluded that inlet water temperature, inlet water mass flow rate, the transmittance of tubes, and absorptance of the absorber surface have a direct effect on the energy and exergy efficiency of the heat pipe evacuated tube solar collector. Increasing water inlet temperature in heat pipe evacuated solar collectors leads to a decrease in heat transfer rate between the heat pipe's condenser and water.

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Section: Introductionmentioning

confidence: 99%

Energy and exergy efficiency of heat pipe evacuated tube solar collectors

2016

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“…A theoretical analysis was performed to investigate the exergetic efficiency of single pass SAHs with fins and baffles by Sabzpooshani et al, 16 and it was concluded that the exergetic efficiency was directly proportional to the air flow rate and the irradiance intensity. Review papers of numerical and experimental studies of the energy and exergy efficiencies of SAHs have been presented by Oztop et al, 17 Kalogirou et al, 18 and Sansaniwal et al 19 The thermal performance of different SAH systems was investigated in term of the first and second laws of thermodynamics by Bahrehmand and Ameri, 20 and they reported that the absorber plate temperature for a double glass cover was greater than that of an absorber plate with a single glass cover. An experimental test was carried out by Edalatpour et al 21 to evaluate the energetic and exergetic performance of an SAH with a double glass cover.…”

Section: Introductionmentioning

confidence: 99%

Analysis of exergetic performance for a solar air heater with metal foam fins

2020

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In this experimental study, an exergetic analysis is presented for solar air heaters (SAHs) that have absorber plates equipped with different fin arrangements. The following two types of fins were used: solid fins (conventional) and metal foam fins. Longitudinal, staggered, and corrugated fin arrangements in SAHs were investigated under the weather conditions experienced in Baghdad, Iraq in February to April 2018. The exergy efficiency and exergy loss of the SAHs were evaluated for five air mass flow rates ranging from 0.011 to 0.059 kg/s. Based on the exergy analysis, SAHs with metal foam fins are more efficient than those with solid fins. In addition, corrugated metal foam fins introduce more turbulent flow than the other fin configurations. It was found that the exergy loss and the exergy efficiency were directly proportional to the values of solar irradiance and air mass flow rates. At solar noon, the maximum values for exergy change were 127 and 89 W/m2 for air mass flow rates of 0.011 and 0.059 kg/s, respectively.

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“…Notably, a reference book deals essentially with the handling of the solar intensity fluctuations on an automatism point of view, on the basis of constant output temperature for the control of large‐scale steam turbines, with or without thermal storage. Since then, it has been shown, by the use of exergy approach that constant output temperature is not optimal, either for steam plants or other plants . The latest references present exergy optimizations of solar plants based on the available exergy flow only.…”

Section: Introductionmentioning

confidence: 99%

Steady state operation exergy‐based optimization for solar thermal collectors

Grosu

Mathieu

Rochelle

et al. 2019

Env Prog and Sustain Energy

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In this investigation, exergy-based optimization was carried out on two configurations of solar thermal collectors. A set of control sensors were utilized to control the performance of the system and monitor the design variables, that is, inlet and outlet temperature of the solar fluid, ambient temperature, incident solar flux, and required mechanical and electrical work in the system. The fluid temperature was considered to vary in the range of 120-180 C with respect to technical and economic considerations. The collector surface area was considered 606 m 2 in both configurations, and a medium solar incident was considered about 520 W/m 2 . The maximum acceptable temperature difference is obtained as function of the input temperature. The technical limitation is plotted for both configurations of solar collectors. It was noticed that the exergy flow of simple evacuated tubes can reach the maximum value when the input temperature is greater than 115 C for an incident solar flow, from 250 W/m 2 up to the limit of 950 W/m 2 . Exergy analysis demonstrated that more control is required on the temperature control to obtain the optimum performance of the solar collector. Thus, applying exergy optimization approach can be very useful to guide control system, the maximum outlet temperature being a key variable on the performance of the collectors.

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Exergy analysis on solar thermal systems: A better understanding of their sustainability

Cited by 163 publications

References 55 publications

Energy and exergy efficiency of heat pipe evacuated tube solar collectors

Energy and exergy efficiency of heat pipe evacuated tube solar collectors

Analysis of exergetic performance for a solar air heater with metal foam fins

Steady state operation exergy‐based optimization for solar thermal collectors

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