Exact and Approximate Analytic Methods to Calculate Maximum Heat Flow in Annular Fin Arrays with a Rectangular Step Profile

2012 ◽  
Vol 33 (7) ◽  
pp. 1314-1333 ◽  
Author(s):  
Balaram Kundu ◽  
Kwan-Soo Lee ◽  
Antonio Campo
Keyword(s):  
Heat Flow ◽  
Maximum Heat ◽  
Analytic Methods ◽  
Annular Fin

scholarly journals Optimisation of the Geometric Parameters of Longitudinally Finned Air Cooler Tubes Operating in Mixed Convection Conditions

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 111
Author(s):  
Piotr Kopeć ◽  
Beata Niezgoda-Żelasko
Keyword(s):  
Heat Flow ◽  
Mixed Convection ◽  
Optimal Solution ◽  
Finned Tube ◽  
Geometric Parameters ◽  
Maximum Efficiency ◽  
Minimum Mass ◽  
Maximum Heat ◽  
Air Cooler ◽  
Finned Surface

The results of optimisation calculations presented in the article are related to longitudinally finned tubes of a heat pump evaporator operating under natural wind-induced flow of outdoor air conditions. The finned surface is characterised by an unusual, wavy fin shape. The article presents the methodology applied to seeking optimal geometric parameters of the finned tube in which thermal calculations were performed by modelling a mixed convection process on the finned surface using the finite volume method. In the case of maximising the heat flow with the minimum mass of the fins, the optimal solution was dominated by the minimum mass of the fins and thus geometric parameters correspond to the number of fins n = 6, fin height h = 0.065 and fin thickness s = 0.0015 m. Optimisation calculations made for maximum efficiency of the exchanger at constant mass indicated that the tube with ten fins (n = 10) with a height of h = 0.11 m and a thickness of s = 0.0018 m allowed maximum heat flow at the assumed mass of the fins in the exchanger tube model. The article proposes a simplified method of determining the optimal geometric parameters of the profile for any mass and maximum thermal efficiency.

scholarly journals Energy analysis of heat exchanger in a heat exchanger network

2018 ◽  
Vol 22 (5) ◽  
pp. 1999-2011 ◽  
Author(s):  
Martina Rauch ◽  
Antun Galovic
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Flow Rate ◽  
Local Extremum ◽  
Heat Flow Rate ◽  
Fluid Stream ◽  
Heat Exchanger Network ◽  
Maximum Heat ◽  
The Given

For many years now, heat exchanger optimization has been a field of research for a lot of scientists. Aims of optimization are different, having in mind heat exchanger networks with different temperatures of certain streams. In this paper mathematical model in dimensionless form is developed, describing operation of one heat exchanger in a heat exchanger network, with given overall area, based on the maximum heat-flow rate criterion. Under the presumption of heat exchanger being a part of the heat exchanger network, solution for the given task is resting in a possibility of connecting an additional fluid stream with certain temperature on a certain point of observed heat exchanger area. The connection point of additional fluid stream determines the exchanging areas of both heat exchangers and it needs to allow the maximum exchanged heat-flow rate. This needed heat-flow rate achieves higher value than the heat-flow rate acquired by either of streams. In other words, a criterion for the existence of the maximum heat-flow rate, as a local extremum, is obtained within this mathematical model. Results of the research are presented by the adequate diagrams and are interpreted, with emphasis on the cases which fulfill and those which do not fulfill the given condition for achieving the maximum heat-flow rate.

scholarly journals Measurements of Counter?Gradient Heat Flows in the Atmosphere

1956 ◽  
Vol 9 (1) ◽  
pp. 133 ◽  
Author(s):  
AF Bunker
Keyword(s):  
United States ◽  
Heat Flow ◽  
East Coast ◽  
Temperature Fluctuations ◽  
Temperature Gradients ◽  
Correct Order ◽  
Maximum Heat ◽  
Heat Flows ◽  
Order Of Magnitude ◽  
The Individual

Heat flows and temperature gradients were measured in a stable atmosphere heated by the water during a United States east coast to Bermuda aeroplane flight. The flux was computed from , where w' and T' are the vertical velocities and temperature deviations of the individual gusts. It is found that the heat flow is directed up the gradient as predicted by Priestley (1954). The expression for the maximum heat flow to be expected derived by Priestley in terms of the standard deviation of the temperature fluctuations and the temperature gradient gives the correct order of magnitude for the observed flow.

Radiation Fin Efficiency for One-Dimensional Heat Flow in a Circular Fin

1959 ◽  
Vol 81 (4) ◽  
pp. 327-329 ◽  
Author(s):  
R. L. Chambers ◽  
E. V. Somers
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Thermal Power ◽  
Steady State Solution ◽  
State Solution ◽  
Design Parameters ◽  
One Dimensional ◽  
Fin Efficiency ◽  
Annular Fin ◽  
The One

The one-dimensional steady-state solution for radiation from one side of an annular fin has been computed for values of the two design parameters 0⩽ϵσθi3Kro-ri⩽2.0 and 1.001⩽ρ=rori⩽15.0. The solution supplies design information needed for satellite thermal-power dissipating surfaces.

scholarly journals Simple heat profiles and biogeochemical patterns for analysis the influence on soil microbial community of plastic-greenhouse and open field condition

2018 ◽  
pp. 960
Author(s):  
Ke Chen ◽  
Mohammad Russel, Changrui Liu ◽  
Jun Yao ◽  
Lifen Liu ◽  
Md. Mahbub Alam ◽  
...  
Keyword(s):  
Microbial Community ◽  
Treatment Group ◽  
Heat Flow ◽  
Open Field ◽  
Soil Microbial Community ◽  
Phospholipid Fatty Acid ◽  
The Other ◽  
Maximum Heat ◽  
Soil Microbial ◽  
N Treatment

The diversity of the soil microbial community is remarkably sensitive to different cropping techniques. To examine the effects of cultivation in a greenhouse on the soil microbial activity and diversity, we collected soil samples from vegetable crops continuously grown in a plastic greenhouse (G) and an open field (N). Heat profiling was obtained using microcalorimeter in the presence of different carbon sources. Power time curves were recorded after glucose and ammonium sulphate supplementation. The total heat release QT (Jg-1), maximum heat flow Pmax (μW) and growth rate constant k (h-1) are higher in G treatment group than the in N treatment group. On the other hand, the time (tmax) to reach the peak heat flow is lower in G treatment group compared to N treatment group, as is cell specific heat rate JQ/N (J cell-1). Sample G1 has the highest Pmax (1246.07 μW) and the lowest tmax (11.86 h); in contrast, sample N5 has the lowest Pmax (411.03 μW) and the highest tmax (21.78 h). The microbial community in the soil was estimated from phospholipid fatty acid (PLFA) biomarkers analysis and a viable count, followed by a subsequent determination of the physicochemical parameters. The total average PLFA concentration range is found as 129.76 - 142.54 nmol g-1. Both thermodynamics properties and PLFA concentration was are significantly greater in G1, G2 and G3 treatment than in the other two (N5 & N6) management systems (P < 0.05). Combination of both thermodynamic and PLFA profiling determines that the microbial population is higher in the soil from the greenhouse fertilization than from the open field cultivation. This novel approach could be applicable to a better understanding of (i) the changes in the soil microbial community in green house and open field cultivation practices, and (ii) the relationship between physicochemical properties and soil microbial community’s diversity. Moreover, this would be a notable technique for the decision maker to choose the potential cultivation method for sustainable green-food development program.

scholarly journals Postcollisional evolution features of the intracontinental structures formed by overthrusting

Georesursy ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 377-385
Author(s):  
O. Parphenuk
Keyword(s):  
Heat Flow ◽  
Heat Generation ◽  
Thermal Evolution ◽  
Complex Model ◽  
Upper Crust ◽  
Initial Temperature Distribution ◽  
Maximum Heat ◽  
Radiogenic Heat ◽  
Surface Uplift ◽  
Mechanical Evolution

The investigation of intracontinental collision structures is conducted based on the complex model of the thermal and mechanical evolution of overthrusting process for the rheologically layered lithosphere, which includes brittle upper crust, the lower crust and lithospheric upper mantle with different effective viscosity values. Finite element models with Lagrangian approach were used for the problem simulation. It was shown that thermal evolution of continental orogens essentially results from the geometry and topography due to thrusting and postcollision stage. This work concentrates on the thermal parameters influence on the evolution of collision zones aimed to the study of possibility of granite melt formation. Calculations for mean continental initial temperature distribution lead to the conclusion of possibility of granite melt formation for the case of “wet” granite solidus. The horizon of temperatures higher than “wet” granite solidus appears at the level of 30-40 km, moving upward to the depth 15-20 km at postcollision stage. The early postcollision evolution shows some heat flow increase due to the thickening of the upper crust with maximum heat generation rate. Further history leads to the stable heat flow values because additional loading redistribution resulting from the denudation of surface uplift and corresponding sedimentation is small due to the local erosion in our model. It was shown that surface heat losses after the termination of horizontal shortening depend to a greater extent on radiogenic heat generation rather than thermal conductivity value in the upper crust.

scholarly journals Assessment of Geothermal Potentials In Some Parts of Upper Benue Trough Northeast Nigeria Using Aeromagnetic Data

2019 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Abdulwahab Mohammed ◽  
Taiwo Adewumi ◽  
Salako Adeyinka Kazeem ◽  
Rafiu Abdulwaheed ◽  
Abbass Adebayo Adetona ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Heat Flow ◽  
Curie Point ◽  
Aeromagnetic Data ◽  
The South ◽  
Maximum Heat ◽  
Entire Study ◽  
Benue Trough ◽  
Depth Analysis ◽  
Western Portion

The assessment of geothermal potentials over part of the upper Benue trough corresponding to Kaltungo, Guyok, Lau and Dong areas, North Eastern Nigeria using spectral depth analysis of aeromagnetic data has been carried out. The study area is bounded by latitudes 9o00’N and 10o00’N and longitudes 11o00’E and 12o00’E. This research work is necessitated by the need for renewable and alternative sources of energy for use in Nigeria. Regional/residual separation was carried out on the total magnetic field using polynomial fitting method of order one. The residual map was divided into nine overlapping blocks for the spectral analysis. The centroid depths and depth to top of basement were obtained from the plot of log of power spectrum against wavenumber. These two parameters were used to estimate the Curie point depth using , where    and  are Curie depth, centroid depth and depth to top of basement respectively. The results from the spectral analysis suggested that in the parts of the Upper Benue trough, the basement is deepest at the south western portion towards the Lau area and varies between 0.55 and 3.8 km, while the centroid depth varies from 7.26 to 18.00 km. From the same portion of the trough, the Curie-point depths vary between 12.43 and 33.91 km and the corresponding geothermal gradient and heat flow values varying from 17.10 to 46.66 0C/km with an average of 30.75 0C/km and 42.75 to 116.65 mW/m2 with an average of 75.91 mW/m2 respectively. The maximum heat flow is found around the south western portion of the study area (Lau). The entire study area with high heat flow values might probably be good sources for geothermal and thereby recommended for both geothermal exploration and exploitation.

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