Research

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15 pages, 3537 KiB

Open AccessArticle

A Thermal Analysis of a Convective–Radiative Porous Annular Fin Wetted in a Ternary Nanofluid Exposed to Heat Generation under the Influence of a Magnetic Field

by Arushi Sharma, B. N. Hanumagowda, Pudhari Srilatha, P. V. Ananth Subray, S. V. K. Varma, Jasgurpreet Singh Chohan, Shalan Alkarni and Nehad Ali Shah

Energies 2023, 16(17), 6155; https://doi.org/10.3390/en16176155 - 24 Aug 2023

Viewed by 672

Abstract

Fins are utilized to considerably increase the surface area available for heat emission between a heat source and the surrounding fluid. In this study, radial annular fins are considered to investigate the rate of heat emission from the surface to the surroundings. The [...] Read more.

Fins are utilized to considerably increase the surface area available for heat emission between a heat source and the surrounding fluid. In this study, radial annular fins are considered to investigate the rate of heat emission from the surface to the surroundings. The effects of a ternary nanofluid, magnetic field, permeable medium and thermal radiation are considered to formulate the nonlinear ordinary differential equation. The differential transformation method, one of the most efficient approaches, has been used to arrive at the analytical answer. Graphical analysis has been performed to show how nondimensional characteristics dominate the thermal gradient of the fin. The thickness and inner radius of a fin are crucial factors that impact the heat transmission rate. Based on the analysis, it can be concluded that a cost-effective annular rectangular fin can be achieved by maintaining a thickness of 0.1 cm and an inner radius of 0.2 cm. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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18 pages, 4399 KiB

Open AccessArticle

Experimental Study of Frost Crystals Dendrite Growth on Two Neighboring Separate Frozen Water Drops on a Cryogenic Cold Surface under Natural Convection Conditions

by Fengjiao Yu, Zhongliang Liu, Yanxia Li, Yanling Chen and Yi Li

Energies 2023, 16(4), 1861; https://doi.org/10.3390/en16041861 - 13 Feb 2023

Viewed by 975

Abstract

The effects of cold surface temperature, wet air state (temperature and humidity) and original drop size on frost dendrites growth of two neighboring separate frozen water drops of same size under natural convection conditions were investigated by quantitative measurement. It was determined that [...] Read more.

The effects of cold surface temperature, wet air state (temperature and humidity) and original drop size on frost dendrites growth of two neighboring separate frozen water drops of same size under natural convection conditions were investigated by quantitative measurement. It was determined that for different cold plate surface temperature conditions, i.e., the ordinary-low temperature and the cryogenic temperature range, the frost formation mechanism is different. Under the conditions that the air temperature is not too high and absolute humidity is not too excessive, the influence of frozen water drop size on the longest dendrite of frost crystals becomes more and more obvious with the decrease in cold plate temperature. The changes in air temperature and relative humidity both change air absolute humidity, so they have similar effects on the growth of dendrites. However, the effect of wet air state on the growth of frost dendrites is not monotonous, which needs to be considered comprehensively in combination with heat and mass transfer and the existence of heavy phase layer. The thickness of ‘the initial continuous frost layer’ was measured and it was disclosed that the initial frost layer thickness is 1.7–3.0 times that of the height of the frozen water drop diameter. This value may be possibly used as initial frost layer thickness in heat and mass transfer-based frost layer growth prediction models, at least for ordinary-low temperature conditions. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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13 pages, 2668 KiB

Open AccessArticle

Reference Test Method for Calculating the Thermal Effect of Coal Spontaneous Combustion

by Wenyong Liu, Wenzhao Zhang, Shuai Ma and Ze Zhang

Energies 2022, 15(20), 7707; https://doi.org/10.3390/en15207707 - 18 Oct 2022

Cited by 1 | Viewed by 964

Abstract

During a heating experiment, there are two sources of heat that increase the temperature of a coal sample: the heat released by the oxidation reaction of the coal itself, and the heat provided by the experimental system. Here, we propose a method for [...] Read more.

During a heating experiment, there are two sources of heat that increase the temperature of a coal sample: the heat released by the oxidation reaction of the coal itself, and the heat provided by the experimental system. Here, we propose a method for measuring the thermal effect of oxidation and self-ignition through a reference experiment conducted with a material that is physically similar to coal but does not combust. The reference material used was an aggregate of alumina, fly ash, and concrete, and experiments were conducted on both materials simultaneously. The temperature of the coal sample was obtained under self-heating conditions, and compared with that of the non-combusting material. The relationship of temperature as a function of time for both materials was determined from the data, the comparison of which allowed for the thermal effect of oxidation and coal spontaneous combustion (CSC) to be calculated. The reliability of the thermal effect data obtained by the experiment was verified by chemical bond energy estimation. These results provide theoretical guidance for on-site fire prevention and extinguishing in coal mines, and are important for the further development of the understanding of CSC. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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22 pages, 8277 KiB

Open AccessArticle

Heat Transfer Characteristics of an Aeroengine Turbine Casing Based on CFD and the Surrogate Model

by Wenlei Lian, Yunfei Jiang, Hao Chen, Yi Li and Xianglei Liu

Energies 2022, 15(18), 6743; https://doi.org/10.3390/en15186743 - 15 Sep 2022

Cited by 1 | Viewed by 1360

Abstract

A good turbine casing cooling design should control the thermal stress and maintain a reasonable tip clearance between the turbine blade and the casing. Since the turbine inlet temperature has been increased yearly, the influence of thermal radiation on the temperature of a [...] Read more.

A good turbine casing cooling design should control the thermal stress and maintain a reasonable tip clearance between the turbine blade and the casing. Since the turbine inlet temperature has been increased yearly, the influence of thermal radiation on the temperature of a turbine casing has become more significant. Therefore, the heat transfer characteristics of a turbine casing considering the radiation effect need to be precisely predicted. In this study, a theoretical model is established for describing the heat transfer characteristics of a turbofan casing, and the model’s effectiveness is verified by comparing the numerical and experimental results. Based on the validated model, the effects of single changes of the wall temperature, cooling air temperature, Reynolds number, and surface emissivity on the heat transfer of the casing are discussed. The results show that the increment of cooling air temperature and surface emissivity leads to the enhancement of the average radiative Nusselt number, and the average convective Nusselt number increases as the Reynolds number increases. The emissivity can improve the temperature distribution uniformity of the turbine casing. Finally, a Kriging surrogate model is fitted with 20 sample points to predict the joint effect of multiple parameters on the casing surface Nusselt number. It is found that the Reynolds number has a more significant influence on the average Nusselt number compared with the emissivity and the temperature ratio. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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13 pages, 2617 KiB

Open AccessArticle

Land Subsidence Assessment for Wind Turbine Location in the South-Western Part of Madagascar

by Dariusz Knez and Herimitsinjo Rajaoalison

Energies 2022, 15(13), 4878; https://doi.org/10.3390/en15134878 - 02 Jul 2022

Cited by 7 | Viewed by 1372

Abstract

Finding a suitable location is a key factor for long-term investment in wind turbine energy. It includes understanding the area of interest, such as the subsidence of the land. Land subsidence is a gradual decrease in the surface of the Earth due to [...] Read more.

Finding a suitable location is a key factor for long-term investment in wind turbine energy. It includes understanding the area of interest, such as the subsidence of the land. Land subsidence is a gradual decrease in the surface of the Earth due to natural and/or induced causes. It can cause damage, such as settlement problems in the ground near infrastructure including buildings and wind turbines, thus not being a suitable place for long-term investment. Here, we show a case study of land subsidence prediction and assessment of the Atsimo Andrefana region, the great south-western part of Madagascar, using theoretical simulation and satellite images from the Sentinel-1 mission using D-InSAR method. The predicted land subsidence related to the depletion of groundwater reservoirs in the Atsimo Andrefana region is around 12 mm. We found ~5 mm of subsidence related to the growing city of Toliary and with an average subsidence of 124 mm and the highest record of 167 mm in the most southern part of the region for a period of 6 months. The spatial distribution of land subsidence allows us to choose the ideal location for wind turbine settlement, where land subsidence is not that severe, i.e., the areas with subsidence relatively low of equal or less than 10 mm within 6 months of observation, based on the processed data. Such results are essential for future environmentally friendly investments in the affected region, as the demand for green energy will always grow. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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19 pages, 6261 KiB

Open AccessArticle

Single-Phase Heat Transfer Characteristics of Water in an Industrial Plate and Shell Heat Exchanger under High-Temperature Conditions

by Kibong Kim, Kang Sub Song, Gilbong Lee, Kichang Chang and Yongchan Kim

Energies 2021, 14(20), 6688; https://doi.org/10.3390/en14206688 - 15 Oct 2021

Cited by 6 | Viewed by 2097

Abstract

This study investigates the single-phase heat transfer, pressure drop, and temperature distribution of water in an industrial plate and shell heat exchanger (PSHE) under high-temperature conditions. In this experiment, the hot fluid flows downward on the plate side, while the cold fluid flows [...] Read more.

This study investigates the single-phase heat transfer, pressure drop, and temperature distribution of water in an industrial plate and shell heat exchanger (PSHE) under high-temperature conditions. In this experiment, the hot fluid flows downward on the plate side, while the cold fluid flows upward on the shell side. In the single-phase heat transfer experiment on water, the Nu is in the range of 7.85–15.2 with a Re from 1200 to 3200, which is substantially lower than that on the plate heat exchanger (PHE) studied previously. The decrease in the Nu is attributed to the reduced cross-sectional heat transfer area from the flow imbalance in the PSHE. As the Re increases, the pressure drop on the plate side increases more rapidly than that on the shell side because of the difference in the port pressure drop, flow direction, and flow position on the plate. When the Re is 2620, the pressure drops on the plate and shell sides are 52.5 kPa and 25.5 kPa, respectively, a difference of 51.4%. The temperature deviation on the circular plate increases as the Re decreases, especially between the edge and bottom of the plate because of uneven flow distribution on the plate. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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19 pages, 4813 KiB

Open AccessArticle

Thermohydraulic Performance and Entropy Generation of a Triple-Pass Solar Air Heater with Three Inlets

by Nguyen Minh Phu, Ngo Thien Tu and Nguyen Van Hap

Energies 2021, 14(19), 6399; https://doi.org/10.3390/en14196399 - 07 Oct 2021

Cited by 15 | Viewed by 1742

Abstract

In this paper, a triple-pass solar air heater with three inlets is analytically investigated. The effects of airflow ratios of the second and third passes (ranging from 0 to 0.4), and the Reynolds number of the third pass (ranging from 8000 to 18,000) [...] Read more.

In this paper, a triple-pass solar air heater with three inlets is analytically investigated. The effects of airflow ratios of the second and third passes (ranging from 0 to 0.4), and the Reynolds number of the third pass (ranging from 8000 to 18,000) on the thermohydraulic efficiency and entropy generation are assessed. An absorber plate equipped with rectangular fins on both sides is used to enhance heat transfer. The air temperature change in the passes is represented by ordinary differential equations and solved by numerical integration. The results demonstrate that the effect of the third pass airflow ratio on the thermohydraulic efficiency and entropy generation is more significant than that of the second pass airflow ratio. The difference in air temperature through the collector shows an insignificant reduction, but the air pressure loss is only 50% compared with that of a traditional triple-pass solar air heater. Increasing the air flow ratios dramatically reduces entropy generation. Multi-objective optimization found a Reynolds number of 11,156 for both the airflow ratio of the second pass of 0.258 and airflow ratio of the third pass of 0.036 to be the an optimal value to achieve maximum thermohydraulic efficiency and minimum entropy generation. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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Review

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25 pages, 361 KiB

Open AccessReview

A Survey of Application of Mechanical Specific Energy in Petroleum and Space Drilling

by Mitra Khalilidermani and Dariusz Knez

Energies 2022, 15(9), 3162; https://doi.org/10.3390/en15093162 - 26 Apr 2022

Cited by 17 | Viewed by 3277

Abstract

The optimization of drilling operations is an ongoing necessity since the major proportion of the terrestrial hydrocarbon reservoirs has been exhausted. Furthermore, there is a growing tendency among the space exploration agencies to drill the subsurface formations of the remote planets, such as [...] Read more.

The optimization of drilling operations is an ongoing necessity since the major proportion of the terrestrial hydrocarbon reservoirs has been exhausted. Furthermore, there is a growing tendency among the space exploration agencies to drill the subsurface formations of the remote planets, such as the Moon and Mars. To optimize the drilling efficiency in such complicated conditions, the mechanical specific energy (MSE) must be efficiently reduced. The available MSE models incorporate the different parameters related to the surface rig, drill bit, and the underlying rocks to estimate the MSE values. In this research, the current status of those MSE models is assessed, and their relevant assumptions, limitations, applications, and pros and cons are profoundly argued. From the current scrutiny, it was deduced that the available MSE models require more geomechanical parameters to be included in their formulations. Furthermore, the use of artificial intelligence (AI) techniques was identified as an effective solution to incorporate such geomechanical parameters in the MSE models. Moreover, the establishment of suitable MSE models for off-Earth drilling applications was also revealed to be very urgent and essential. The performed analyses together with the comparative assessments are contributing factors for the modification and establishment of future MSE models. Full article

(This article belongs to the Special Issue Fluid Flow and Heat Transfer Analysis in Industrial Applications)

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