Numerical study for estimation of temperature distribution in solar pond in diverse climatic conditions for all cities of Turkey

2020

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In this study, a new perspective was introduced to conventional solar pond technology to spread its commercial application. In order to make it more useful with preserving energy efficiency, the brine layers were replaced with the normal freshwater by using a separated transparent partition. Structurally modified three different solar ponds were proposed and numerical investigations were conducted by using discrete ordinate method (DOM). For this, four types of solar ponds were modeled, the first one is the conventional salt‐gradient solar pond and three others are modified versions which are named as “Pure Water Solar Pond.” For all models, a comprehensive finite element method was developed to investigate the daily performance of solar ponds by using commercial software COMSOL. Salt‐gradient solar pond consists of seven layers where one layer is the heat storage zone, five layers are nonconvective zone, and one is the upper convective zone. However, in the modified models, solar ponds consist of two glass layers and one to three pure water zones depending on the model types. The numerical method includes a novel approach to calculate all the zone where absorption, emission, scattering, transmission, convection, and radiation are taken into account. Numerical results for all models were compared with an experiment to correlate the numerical accuracy of the DOM with anisotropic scattering phase function. Results indicate there is a good correlation between these four model approach and the experiment.

Section: Meshing and Boundary Conditionsmentioning

confidence: 95%

A new perspective to the conventional solar pond technology to increase the thermal efficiency

2020

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“…Heat transfer in liquid, solid, and boundary with the air was calculated with Equation ) 21

ρ C_{P} ((), \frac{\partial T}{\partial t} + u_{trans} . \nabla T) + \nabla . ((), boldq bold+ q_{r}) = - italicαT : \frac{dS}{dt} + Q

where, ρ is density, C P is the specific heat capacity at the constant stress, T is the absolute temperature, q is the heat flux by conduction and q r is by radiation depends on the medium, α is the coefficient of thermal expansion, u trans is the velocity vector of translational motion, S is the second Piola‐Kirchhoff stress tensor, Q contains additional heat sources.…”

Section: Methodsmentioning

confidence: 99%

“…29,30 In other studies, heat transfer equations in the discrete ordinate method and Kays-Crawford model were tested and correlated with experiments. 21,31 5 section to along the surface and after reaching the lowest speed at a certain distance, it started to accelerate again excluding 5 cm in the barbs (Figure 5b). Figure 3a indicates that temperature increases from inlet to outlet section due to the slowing down of the wind.…”

Section: Adaptability and Verificationmentioning

confidence: 98%

“…20 Heat transfer in liquid, solid, and boundary with the air was calculated with Equation (1). 21 ρC P ∂T ∂t + u trans :rT…”

Section: Hairy Surface Modelmentioning

confidence: 99%

“…In some other studies, the consistency of numerical study with the SST turbulence model was tested and verified with experimental observation 29,30 . In other studies, heat transfer equations in the discrete ordinate method and Kays‐Crawford model were tested and correlated with experiments 21,31 …”

Section: Adaptability and Verificationmentioning

confidence: 99%

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Effect of hairy surface on heat production and thermal insulation on the building

2020

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In the extreme wind and cold weather conditions, animals have developed incredible protection techniques in order to achieve the regulation of body thermal insulation. While birds fluff their feathers to reduce heat loss, some animals take advantage of the other varying unique structures of the skin. In this study, inspired by birds, the effect of hairy surfaces like hedgehog skin on thermal insulation and also heat production at the low-speed wind on the building wall surface was investigated numerically by using the finite element method. For this, a portion of the wall surface was covered with rigid barbs to increase friction on the wall, and for the comparison, a part of the surface was left smooth without any coating. Menter's shear stress transport (SST) turbulence model by algebraic multigrid solver was used for the modeling of wind motion and heat transfer equations by direct solver PARDISO was used to simulate heat transfer in the solid and fluid environment. According to the numerical calculation, the wind speed slows down along the rough surface, high-pressure zone on the surface (a thick no-slip boundary region) was created and a part of wind energy was converted to extra heat and especially the convective heat loss due to the movement of the wind on the surface was reduced, and finally, the building was insulated further by creating a stagnant air layer in the barbs.

The investigation of heat storage efficiency of salt gradient solar pond with and without phase changing materials

Bozkurt

Genç

et al. 2023

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In this work, the effect of with and without phase change materials for long‐term heat storage of a salt gradient solar pond was investigated both experimentally and numerically. Some phase change materials, whose thermal values are close to the operating temperature of the solar pond were selected and examined from fatty acids (camphene, decanoic acid, and palmitic acids) and paraffin derivatives (paraffin wax, C20‐C33, and C16‐C28). A series of experimental studies were then performed with phase change temperature, latent heat and thermal stability, a differential scanning calorimetry, and a thermogravimetric analyzer for sheath, decanoic acid, and palmitic acid. The temperature and enthalpy curve of each phase change material was calculated by months and compared to the solar pond and the longest‐term heat storage was determined. Study shows that the maximum efficiency of the solar pond can be achieved with 24.58% Camphene in November and 22.57% Paraffin C20‐C33 in December. Thus, the camphene shows the best longest‐term heat storage performance thanks to its high melting temperature and density and latent fusion heat. It is one of the best suitable options to improve the heat storage performance of solar ponds.