Convection coefficient equations for forced air flow over flat surfaces

Sartori, Ernani

doi:10.1016/j.solener.2005.11.001

Cited by 139 publications

(61 citation statements)

References 10 publications

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“…The boundary layer theory is the basis of the science on convection heat and mass transfer, is based on first principles verified experimentally and is mandatory for any fluid flow over wet and dry surfaces. Also, as demonstrated [9,23], the evaporation and the convection coefficient depend on V 0.8 and L -0.2 (for turbulent flow) and not linearly on V and L, as used in the 13 and in the lots of other equivalent equations obtained empirically.…”

Section: Discussionmentioning

confidence: 96%

The Physical Principles Elucidate Numerous Atmospheric Behaviors and Human-Induced Climatic Consequences

Sartori¹

2012

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The principles that govern the operation of an open and a closed evaporator are relevant for the understanding of the open and "closed" Earth's atmospheric behaviors, and are thus described. In these greenhouses, the water is included, otherwise the heat and mass balances do not match. It is incorrect to consider the radiation as the only energy transfer factor for an atmospheric warming. Demonstrations show that when the greenhouse effect and the cloud cover increase, the evaporation and the wind naturally decrease. Researchers did not understand why reductions in surface solar radiation and pan evaporation have been simultaneous with increased air temperature, cloudiness and precipitation for the last decades. It is an error to state that the evaporation increases based solely on the water and/or air temperatures increase. Also, researchers did not comprehend why in the last 50 years the clouds and the precipitation increased while the evaporation decreased and they named such understanding as the "evaporation paradox", while others "found" "the cause" violating the laws of thermodynamics, but more precipitation is naturally conciliatory with less evaporation. The same principle that increases the formation of clouds may cause less rainfall. Several measurements confirm the working principles of greenhouses described in this paper. The hydrological cycle is analyzed and it was also put in form of equation, which analyses have never been done before. The human influence alters the velocity of the natural cycles as well as the atmospheric heat and mass balances, and the evaporation has not been the only source for the cloud formation. It is demonstrated that the Earth's greenhouse effect has increased in some places and this proof is not based only on temperatures.

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Section: Discussionmentioning

confidence: 96%

The Physical Principles Elucidate Numerous Atmospheric Behaviors and Human-Induced Climatic Consequences

Sartori¹

2012

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“…Ilegbusi (1989) described the calculation of a turbulent boundary layer on a porous flat plate with severe injection at different rates and at different angles to the surface using two turbulent models, namely, the k-ω (Ilegbusi and Spalding, 1989) and k-ε (Launder and Spalding, 1974) models. Various comparisons among well-known equations of the convection heat transfer coefficient and those that come from the boundary layer theory for forced air flow over flat surfaces and particularly over flat plate solar collectors, with the aim at arriving at a consensus on which of such equations is more accurate, are carried out by Sartori (2006). Also, several attempts have been made over the years to develop generalized Nusselt number correlations that would apply to a range of Reynolds and Prandtl numbers.…”

Section: Frontiers In Heat and Mass Transfermentioning

confidence: 99%

An Integral Energy Equation Model for Heat Convection to Turbulent Boundary Layer on a Flat Plate

Khademi¹,

Mozafari²

2016

Frontiers in Heat and Mass Transfer

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An integral energy equation model is used to calculate the heat transfer coefficient/Nusselt number, thermal boundary layer thickness and temperature distribution in the turbulent boundary layer for forced convection over a smooth flat plate. The proposed model is based on two polynomial temperature profiles in a thermal laminar sublayer as well as in a fully developed boundary layer and two integral energy equations. The performance of this new model is compared with the most commonly used semi-empirical correlations and the complex established models such as k-ε, k-ω, RSM, and a good agreement is achieved.

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“…The Sartori equation [4] [7] [8] [15] is the only one that takes into account the environmental factors that influence evaporation, and it also showed to be very accurate and the most accurate equation in comparison to experimental data and to lots of empirical formulas [4] [7], and then it is used here for this demonstration. This Sartori equation, among other things, is based on the boundary layer theory in the same way as the Sartori equation [6] is for the convection coefficient, which one also proved to be the most accurate in comparison to lots of empirical expressions (obtained from specific experiments and corresponding methods) carried out by the excellent work [16] and by [6] [17]:…”

Section: The Physical and Mathematical Demonstrationsmentioning

confidence: 99%

Climate Changes: How the Atmosphere Really Works

Sartori¹

2015

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Top concepts adopted by the current science on climate changes or atmospheric warming are not in agreement with the first principles of the physics. This paper presents a new understanding on the atmospheric behaviors. For example, the radiation is not the only factor that influences the air temperature, as the law of conservation of energy defines and as shown physically and mathematically in this article. The Sun is not the only heat source for the atmosphere because there is generation of heat at the Earth's surface by human activities. It is also shown that the water vapor is not a null effect and that the water vapor cannot be removed from the atmosphere for air temperature, greenhouse effect and climate changes considerations, in contrast to the current literature beliefs. The "feedback" concept is unfounded and invalid. The literature also says that "water vapor increases as the Earth's atmosphere warms", but this is also incorrect. The above equivocated understanding is accompanied by another one which believes that more water evaporates if the air temperature increases, but it is not in this way. These demonstrations and other authors' surveys showing that in the last decades the planet became wetter eliminate the literature concept that the water vapor does not have influence on the atmospheric warming/cooling. The conventional water cycle is related to the mass of water (mass of evaporation  mass of precipitation) and then the physical and mathematical principles of the new hydrological cycle that includes the direct human influence are shown. The same is done for the carbon cycle. It is solved the problem on why the wind speed on Venus is very high above the cloud deck while it is stagnant below it, being this the same physical principle valid for the Earth's cloud cover. In the atmosphere, all the corresponding principles are the same, only their amounts change. It is demonstrated that the CO2 is not decisive for building and changing the temperatures of Venus, Mars, Mercury, Jupiter and Earth. Ice cores are not valid for "determining" "past" temperatures of the planet, because the mass of their air bubbles may be old, but the corresponding temperatures are not.

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Convection coefficient equations for forced air flow over flat surfaces

Cited by 139 publications

References 10 publications

The Physical Principles Elucidate Numerous Atmospheric Behaviors and Human-Induced Climatic Consequences

The Physical Principles Elucidate Numerous Atmospheric Behaviors and Human-Induced Climatic Consequences

An Integral Energy Equation Model for Heat Convection to Turbulent Boundary Layer on a Flat Plate

Climate Changes: How the Atmosphere Really Works

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