scholarly journals Thermal Simulation of Rolled Concrete Dams: Influence of the Hydration Model and the Environmental Actions on the Thermal Field

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 858 ◽  
Author(s):  
Cristian Ponce-Farfán ◽  
David Santillán ◽  
Miguel Á. Toledo

Mathematical models for the simulation of the thermal evolution of roller-compacted concrete (RCC) dams during construction constitute an important tool for preventing excessive temperature rise, which may lead to cracking and losses of functionality. Here, we present a framework for the simulation of the thermal process. We define the boundary conditions of the problem using a careful description that incorporates the main heat exchange mechanisms. We adopt both a non-adiabatic and an adiabatic heat generation model for the simulation of the cement hydration. Our numerical framework lets us study the effect of the adopted heat generation model on the thermal field. Moreover, we study the influence of the weather conditions on the evolution of the hydration, and on the starting date of construction. Our simulations have shown that the hydration model has an important influence over the temperature field during the construction and the heat generation rate. Moreover, the hydration process and the temperature evolution are driven by the weather conditions. Once the next lift is cast, its thermal insulation effect makes the hydration take place under quasi-adiabatic conditions. As expected, dams built in cold months are prone to dissipate more heat than those built in warm seasons.

2010 ◽  
Vol 37 (4) ◽  
pp. 600-610 ◽  
Author(s):  
Vladan Kuzmanovic ◽  
Ljubodrag Savic ◽  
John Stefanakos

This paper presents two-dimensional (2D) and three-dimensional (3D) numerical models for unsteady phased thermal analysis of RCC dams. The time evolution of a thermal field has been modeled using the actual dam shape, RCC technology and the adequate description of material properties. Model calibration and verification has been done based on the field investigations of the Platanovryssi dam, the highest RCC dam in Europe. The results of a long-term thermal analysis, with actual initial and boundary conditions, have shown a good agreement with the observed temperatures. The influence of relevant parameters on the thermal field of RCC dams has been analyzed. It is concluded that the 2D model is appropriate for the thermal phased analysis, and that the boundary conditions and the mixture properties are the most influential on the RCC dam thermal behavior.


Author(s):  
Najib Hdhiri ◽  
Brahim Ben Beya

Purpose The purpose of this study is to investigate the effects of heat generation or absorption on heat transfer and fluid flow within two- and three-dimensional enclosure for homogeneous medium filled with different metal liquid. Numerical results are presented and analyzed in terms of fluid flow, thermal field structures, as well as average Nusselt number profiles over a wide range of dimensionless quantities, Grashof number (Gr) (104 and 105), SQ (varied between −500 to 500) and Prandtl number (Pr = 0.015, 0.024 and 0.0321). The results indicate that when the conductive regime is established for a Grashof number Gr = 104, the 2D model is valid and predicts all three-dimensional results with negligible difference. This was not the case in the convective regime (Gr = 105) where the effect of the third direction becomes important, where a 2D-3D difference was seen with about 37 per cent. Also, in most cases, the authors find that the heat absorption phenomena have the opposite effect with respect to the heat generation. Design/methodology/approach Numerical results are presented and analyzed in terms of fluid flow, thermal field structures, as well as average Nusselt number profiles over a wide range of dimensionless quantities. Findings Grashof number (Gr) (104 and 105), SQ (varied between −500 to 500) and Prandtl number (Pr = 0.015, 0.024 and 0.0321). Originality/value The results indicate that when the conductive regime is established for a Grashof number Gr = 104, the 2D model is valid and predicts all three-dimensional results with negligible difference.


Author(s):  
T. Kowitkulkrai ◽  
A. Kaewpradap ◽  
S. Hirai ◽  
V. Lailuck ◽  
S. Rompho ◽  
...  

2013 ◽  
Vol 2 (4) ◽  
pp. 370-375 ◽  
Author(s):  
Vijay Shivaji Gadakh ◽  
Kumar Adepu

Author(s):  
Nur Hazima Faezaa Ismail ◽  
Siti Fauziah Toha ◽  
Nor Aziah Mohd Azubir ◽  
Nizam Hanis Md Ishak ◽  
Mohd Khair Hassan ◽  
...  

2013 ◽  
Vol 20 (3) ◽  
pp. 423-428
Author(s):  
R. N. Singh ◽  
A. Manglik

Abstract. Depth distribution of radiogenic heat sources in continental crust is an important parameter that controls its thermal structure as well as the mantle heat flow at the base of continental lithosphere. Various models for the depth distribution of radiogenic heat sources have been proposed. Starting from constant and exponential models based on linear heat flow–heat generation relationship the present-day layered models integrate crustal structure and laboratory measurements of radiogenic heat sources in various exposed rocks representing crustal composition. In the present work, an extended entropy theory formalism is used for estimation of radiogenic heat sources distribution in continental crust based on principle of maximum entropy (POME). The extended entropy principle yields a constant heat generation model if only a constraint given by total radiogenic heat in the crust is used and an exponential form of radiogenic heat sources distribution if an additional constraint in the form of a second moment is used in the minimization of entropy.


2014 ◽  
Vol 903 ◽  
pp. 200-205
Author(s):  
Irfan Hilmy ◽  
Erry Yulian Triblas Adesta ◽  
Muhammad Riza

Friction Stir Welding (FSW) is getting its popularity because it is considered as an environmentally friendly manufacturing. Homemade FSW tool to be attached to a conventional milling machine was designed and fabricated. Experimental investigation of FSW process of the Aluminum alloy work piece to observe its heat generation was performed. Since heat generation is the main objective in a FSW process, the importance of identification of heat generation performance in a welded specimen is paramount. Heat generation of a welded specimen during FSW was measured using infra red thermal camera. The limitation of the measurement is it only captured the heat generation at surrounding area and surface of the welded specimen. Therefore, the heat generation inside contact area could not be identified. To overcome this problem, a finite-element model of the FSW process was developed. A model consists of a solid model of half the welded specimen since the symmetrical behavior of the geometry and boundary condition was assumed. Heat transfer analysis of a solid body model of a work piece was computed. It was observed that FSW parameters which involved dominantly in the heat generation were spindle speed, feeding rate and normal force. The heat generation model of FSW process was validated with the one from the experimental investigation. Good agreement between the numerical and the experimental investigation result has been made.


2017 ◽  
Vol 34 (1) ◽  
pp. 10-19 ◽  
Author(s):  
J. Marino-Salguero ◽  
J. Jorge ◽  
J.M. Menendez-Aguado ◽  
B. Alvarez-Rodriguez ◽  
J.J. de Felipe

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