The thermal analysis in a cylindrical pipe with surface cooling and possible heat loss

2018 ◽  
Vol 37 (1) ◽  
pp. 57-69
Author(s):  
Anthony Rotimi Hassan ◽  
Hammed Abiodun Ogunseye ◽  
Jacob Abiodun Gbadeyan

Investigation of the thermal analysis of a conventional (uncoated) diesel piston made up of Aluminum silicon alloy was carried out in this present study. Secondly, thermal analysis was performed on piston crown, coated with 20% Al2O3 & 80% Yttria Stabilized Zirconia material. TBC comes with two layers; the first layer is a bond coating with NiCoCrAlY compound. The second layer with TBC material (20% Aluminum oxide & 80% Yttria Stabilized Zirconia). The method of multilayer coating was achieved through the Air Plasma spraying technique. Using the coated piston the required temperature in the combustion chamber will be maintained. This will reduce the heat loss to the piston. This reduction in the heat loss will be used to burn the un-burnt gases thereby reducing the polluted exhaust gases. Result will be shown as the thermal efficiency of the coated piston at full load will be increased than uncoated piston and the oxides of nitrogen will be increased.


2008 ◽  
Vol 38 (12) ◽  
pp. 2704-2721 ◽  
Author(s):  
Michael A. Spall

Abstract The issue of downwelling resulting from surface buoyancy loss in boundary currents is addressed using a high-resolution, nonhydrostatic numerical model. It is shown that the net downwelling is determined by the change in the mixed layer density along the boundary. For configurations in which the density on the boundary increases in the direction of Kelvin wave propagation, there is a net downwelling within the domain. For cases in which the density decreases in the direction of Kelvin wave propagation, cooling results in a net upwelling within the domain. Symmetric instability within the mixed layer drives an overturning cell in the interior, but it does not contribute to the net vertical motion. The net downwelling is determined by the geostrophic flow toward the boundary and is carried downward in a very narrow boundary layer of width E1/3, where E is the Ekman number. For the calculations here, this boundary layer is O(100 m) wide. A simple model of the mixed layer temperature that balances horizontal advection with surface cooling is used to predict the net downwelling and its dependence on external parameters. This model shows that the net sinking rate within the domain depends not only on the amount of heat loss at the surface but also on the Coriolis parameter, the mixed layer depth (or underlying stratification), and the horizontal velocity. These results indicate that if one is to correctly represent the buoyancy-forced downwelling in general circulation models, then it is crucial to accurately represent the velocity and mixed layer depth very close to the boundary. These results also imply that processes that lead to weak mixing within a few kilometers of the boundary, such as ice formation or freshwater runoff, can severely limit the downwelling forced by surface cooling, even if there is strong heat loss and convection farther offshore.


Anaesthesia ◽  
1961 ◽  
Vol 16 (2) ◽  
pp. 135-150 ◽  
Author(s):  
D. J. WATERS ◽  
W. W. MAPLESON
Keyword(s):  

2011 ◽  
Vol 346 ◽  
pp. 564-571
Author(s):  
Qing Chun Hu ◽  
Li Ming Wang ◽  
Ming Zhen Tang ◽  
Yong Sheng Wang

The influence of the heat loss of hot runner on the stability of mold injecting process was analyzed. Determine the lost power of heating elements by establishing of hot runner system. Using ANSYS codes to calculate the temperature control equations and get the temperature distribution of hot runner plate. Make the structural arrangement of heating pipes and thermocouples better and ensure thermal equilibrium of the hot runner system by analyzing the temperature field.


2018 ◽  
Vol 20 ◽  
pp. 124-142
Author(s):  
R. Soares Gomez ◽  
A.G. Barbosa de Lima ◽  
T.R. Nascimento Porto ◽  
J. Lacerda de Oliveira ◽  
Morgana Vasconcellos Araújo ◽  
...  

The ceramic products processing requires a high consumption of energy. Through the drying and firing stages, the molded product is subjected to high temperatures in a kiln, to obtain the product with required levels of rigidity and resistance. This energy consumption must be evaluated to improve the energy efficiency of the process. This work presents the fundamentals of ceramic materials processing and perform a thermal analysis in an intermittent ceramic kiln. This analysis is based on heat transfer measurements, that occur in the kiln during the ceramic production stages, and effects of the thermal insulation thickness on the heat transfer between the kiln and the environment. The results showed that a considerable amount of energy is used to heat the kiln surfaces, that the greatest heat loss occurs by radiation of the kiln walls and that the use of thermal insulation provides considerable reduction in this heat loss, as well as the reduction in kiln external temperature, which minimize thermal discomfort and work accident risks.


2018 ◽  
Vol 48 (11) ◽  
pp. 2627-2647 ◽  
Author(s):  
Xiaodong Wu ◽  
Douglas Cahl ◽  
George Voulgaris

AbstractThe formation of coastal dense shelf water in winter provides the available potential energy (APE) to fuel baroclinic instability. The combined effects of baroclinic instability and wind forcing in driving cross-shelf exchange are investigated using idealized numerical simulations with varied bottom slope, wind stress, and heat loss rate. The results show that under upwelling-favorable winds, the intensity of the instability decreases as the wind stress increases. This is caused primarily by enhanced turbulence frictional dissipation. Under downwelling-favorable winds, an increase in wind stress and/or a decrease in heat loss rate tends to constrain the baroclinic instability, leading to a circulation resembling that driven purely by wind forcing. In the latter case, once a critical value of cross-shore density gradient is reached, isopycnal slumping is initiated, leading to increased vertical stratification and narrowing of the inner shelf. The change in depth of the inner-shelf outer boundary, defined as the location corresponding to the maximum cross-shore gradient of the surface Ekman transport, is proportional to an empirically derived multiparametric quantity , where a2 is a dimensional constant, B0 is a constant heat loss rate, γ = 0.43, f is the Coriolis parameter, α is the shelf slope, B is the heat loss rate, and τ is the wind stress. This relationship is found to hold for cases when instabilities are present.


1962 ◽  
Vol 6 (3) ◽  
pp. 260???261
Author(s):  
D. J. WATERS ◽  
W. W. MAPLESON ◽  
ROBERT W. VIRTUE
Keyword(s):  

2013 ◽  
Vol 787 ◽  
pp. 731-735 ◽  
Author(s):  
Jose Vercher ◽  
Carlos Lerma ◽  
Marisol Vidal ◽  
Enrique Gil

Façade-slab connection is the main thermal bridge of buildings. In this work, different options are analyzed according to the location of the thermal insulation. Heat loss is measured for each option. According to thermal analysis performed we conclude that cover the buildings façade completely without interruption at the slabs front is essential to avoid thermal bridges. The new option that interrupts the cantilever to put insulation on the entire façade is just effective to isolate the entire cantilever and is an easier constructive solution. This insulation continuity is needed to prevent ceiling condensation, since the energy saving is not important compared to windows thermal loss.


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