scholarly journals Impingement Density Analysis on Heat Transfer and the Appearance of Edge Cracks in Conventional Slab Using Hydraulic Nozzles

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 108
Author(s):  
Alfonso Ruiz-Pineda ◽  
Alicia Aguilar-Corona ◽  
Constantin Alberto Hernández-Bocanegra ◽  
José Ángel Ramos-Banderas ◽  
Gildardo Solorio-Díaz ◽  
...  

In this work, the fluid dynamics and heat transfer of two hydraulic nozzles used in the secondary cooling of the conventional slab continuous casting machine were analyzed. Impingement density maps, the jet opening angle and heat flux associated with different operating conditions (impingement distance, pressure) were experimentally determined. The opening angle and impingement density footprint were found to vary considerably in shape and magnitude with varying operating pressure and distances. Finally, it was found that when short operating distances are used, a greater heat extraction gradient occurs in the major axis of the impingement footprint, which promotes edge-cracks in the slab in plant.

Author(s):  
Giuseppe Starace ◽  
Lorenzo Falcicchia ◽  
Pierpaolo Panico ◽  
Maria Fiorentino ◽  
Gianpiero Colangelo

AbstractIn refrigeration systems, evaporative condensers have two main advantages compared to other condensation heat exchangers: They operate at lower condensation temperature than traditional air-cooled condensers and require a lower quantity of water and pumping power compared to evaporative towers. The heat and mass transfer that occur on tube batteries are difficult to study. The aim of this work is to apply an experimental approach to investigate the performance of an evaporative condenser on a reduced scale by means of a test bench, consisting of a transparent duct with a rectangular test section in which electric heaters, inside elliptical pipes (major axis 32 mm, minor axis 23 mm), simulate the presence of the refrigerant during condensation. By keeping the water conditions fixed and constant, the operating conditions of the air and the inclination of the heat transfer geometry were varied, and this allowed to carry out a sensitivity analysis, depending on some of the main parameters that influence the thermo-fluid dynamic phenomena, as well as a performance comparison. The results showed that the heat transfer increases with the tube surface exposed directly to the air as a result of the increase in their inclination, that has been varied in the range 0–20°. For the investigated conditions, the average increase, resulting by the inclination, is 28%.


2007 ◽  
Vol 27 (5) ◽  
pp. 256-259
Author(s):  
V. I. Kadoshnikov ◽  
I. M. Yachikov ◽  
V. I. Zav’yalov ◽  
A. A. Podosyan

2009 ◽  
Vol 24 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Ahmed Rahmani ◽  
Ahmed Dahia

In this work, we are interested to simulate the thermal-hydraulic behavior of three-pass type fire-tube boiler. The plant is designed to produce 4.5 tons per hour of saturated steam at 8 bar destined principally for heating applications. A calculation program is developed in order to simulate the boiler operation under several steady-state operating conditions. This program is based upon heat transfer laws between hot gases and the fire-tube internal walls. In the boiler combustion chamber, the heat transfer has been simulated using the well-stirred furnace model. In the convection section, heat balance has been carried out to estimate the heat exchanges between the hot gases and the tube banks. The obtained results are compared to the steady-state operating data of the considered plant. A comparative analysis shows that the calculation results are in good agreement with the boiler operating data. Furthermore, a sensitivity study has been carried out to assess the effects of input parameters, namely the fuel flow rate, air excess, ambient temperature, and operating pressure, upon the boiler thermal performances.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
M. Imtiaz Hussain ◽  
Jun-Tae Kim

The focus of this paper is to predict the transient response of a nanoengineered photovoltaic thermal (PV/T) system in view of energy and exergy analyses. Instead of a circular-shaped receiver, a trapezoidal-shaped receiver is employed to increase heat transfer surface area with photovoltaic (PV) cells for improvement of heat extraction and thus achievement of a higher PV/T system efficiency. The dynamic mathematical model is developed using MATLAB® software by considering real-time heat transfer coefficients. The proposed model is validated with experimental data from a previous study. Negligible discrepancies were found between measured and predicted data. The validated model was further investigated in detail using different nanofluids by dispersing copper oxide (CuO) and aluminum oxide (Al2O3) in pure water. The overall performance of the nanoengineered PV/T system was compared to that of a PV/T system using water only, and optimal operating conditions were determined for maximum useful energy and exergy rates. The results indicated that the CuO/water nanofluid has a notable impact on the energy and exergy efficiencies of the PV/T system compared to that of Al2O3/water nanofluid and water only cases.


Author(s):  
Yaser Mollaei Barzi ◽  
Mohsen Assadi

In this study, a preliminary investigation is carried out concerning the possibility and feasibility of recovering part of the side walls heat loss to use it in an energy utilization system. For this purpose, a simple smart heat transfer model is developed for the aluminum smelter side lines accounting for the dynamic ledge profile variations and phase change. Using the model, the total side wall heat loss is estimated and evaluated in different operating conditions of the cell. The system flexibility and self-adjustment ability are taken in to account to find the appropriate solution for the heat extraction system. Using the above-mentioned analysis, the heat recovery strategy and also the possible and applicable alternatives for the side walls heat collection and utilization system are investigated.


2009 ◽  
Vol 39 (2) ◽  
pp. 103-107
Author(s):  
S. V. Feiler ◽  
E. V. Protopopov ◽  
V. P. Komshukov ◽  
L. A. Ganzer

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