Determination of stagnation and convective zones in a solar cavity receiver

Prakash, Mahesh; Kedare, Shireesh B.; Nayak, J.K.

doi:10.1016/j.ijthermalsci.2009.06.015

Cited by 48 publications

(21 citation statements)

References 23 publications

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“…Wu et al [16] reviewed different possible situations in convection losses; concluding that an inclination close to 90° makes the stagnant zone fill the cavity interior space; therefore, a stable temperature stratification is generated, which reduces the convective losses to negligible values. The distribution of this stagnation zone distribution was researched by Prakash et al [17], and the wind influence in that zone was studied by Xiao et al [18], who illustrated the wind velocity, wind inclination, and cavity inclination influence in the final convection losses. Wu et al [19] studied natural convection heat loss variation, concluding that it is more sensitive to tilt angle and aperture size, except when tilt angle is 90° (when the stagnant zone fills the interior space).…”

Section: Introductionmentioning

confidence: 99%

Thermal Model of a Dish Stirling Cavity-Receiver

et al. 2015

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This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to determine the optimal cavity design. The tool has been used to study the cavity optimization regarding geometry parameters and material properties. Receiver absorptivity has been identified as the most influential property of the materials. The optimal aperture height depends on the minimum focal space.

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Section: Introductionmentioning

confidence: 99%

Thermal Model of a Dish Stirling Cavity-Receiver

et al. 2015

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“…It should be pointed out that in the investigations just descdribed, the general boundary conditions were that the cavity walls had uniform temperature or one wall had uniform temperature and the other walls were considered adiabatic [5]. However, in some practical applications the cavities are subjected to constant heat flux boundary conditions, and the results summarized thus far may not accord with the facts and cannot be referenced by simple transplantation.…”

Section: Introductionmentioning

confidence: 99%

“…The concept of the stagnation zone and the convection zone was first proposed. Recently, Prakash et al [5] performed experimental and numerical studies to identify these two zones in a cylindrical cavity with a wind skirt, and a parameter called "critical air temperature gradient" was defined for this purpose. A Nusselt number incorporating inclination and aperture size was developed by Koenig and Marvin [6] based on the study of cylindrical cavity.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation and Uncertainty Analysis on Combined Heat Losses Characteristics of a Cylindrical Cavity with Only Bottom Wall Heated at Constant Heat Flux

Shen

Xiao

2014

Heat Transfer Engineering

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An experiment was performed to explore the effects of inclination, aperture ratio, and heat flux on heat losses of a fully or partially open cylindrical cavity, where only the bottom wall (opposite to the aperture) was heated at constant heat flux. Temperature distributions on cavity bottom and side walls are presented. The empirical correlations of free convection and radiation heat losses in terms of Nusselt number are proposed. The credibility of the experiments was checked by detailed uncertainty analysis. It confirmed that the present experimental results are credible and can be used to validate the relevant numerical codes. In addition, the cavity inclination, aperture ratio, and heat flux significantly affect the combined heat losses characteristics, and the influence of these factors, which is intercoupled to some extent, should be considered at the same time.

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“…In this study the accuracy of the nite volume (FV) method was evaluated in comparison to Monte Carlo (MC) techniques for both the concentrated solar energy and the energy emitted by heated surfaces in a receiver. The stagnation and convective zones in a solar cavity receiver were determined by Prakash, Kedare, and Nayak [13]. They carried out experimental and numerical studies to identify these zones.…”

Section: Introductionmentioning

confidence: 99%

First and second thermodynamic law analyses applied to a solar dish collector

Madadi¹,

Tavakoli²,

Rahimi³

2014

Journal of Non-Equilibrium Thermodynamics

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The energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The e ect of receiver type, inlet temperature and mass ow rate of heat transfer uid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the e ect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal e ciency. The cylindrical receiver has greater energy and exergy e ciency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy e ciency is minimum for a speci ed HTF mass ow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass ow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass ow rates than the above mentioned values are recommended.

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Determination of stagnation and convective zones in a solar cavity receiver

Cited by 48 publications

References 23 publications

Thermal Model of a Dish Stirling Cavity-Receiver

Thermal Model of a Dish Stirling Cavity-Receiver

Experimental Investigation and Uncertainty Analysis on Combined Heat Losses Characteristics of a Cylindrical Cavity with Only Bottom Wall Heated at Constant Heat Flux

First and second thermodynamic law analyses applied to a solar dish collector

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