Numerical Investigation of Heat Transfer Enhancement in a Circular Tube with Rectangular Opened Rings

Turbulent forced convection of coolant air flow (10 m/s velocity) in a steel tube of 50 cm long having outside diameter of 60 mm and inside diameter of 30 mm with constant outside surface temperature of 1000, 1200 and 1400 Ko is numerically analyzed. The renormalization group k-ε model is used to simulate turbulence in ANSYS - FLUENT 14.5. An opened ring of rectangular cross section (5x7 mm) is fitted in the tube and separated by 8cm pitch. Results of temperature and velocity distribution along the tube center line for the case of tube with internal ribs  were compared with that of plain tube  , these results show that the use of internal ribs enhance the heat transfer rate and found to possess the highest performance factors for turbulent flow

NUMERICAL INVESTIGATION OF HEAT TRANSFER ENHANCEMENT IN A CIRCULAR TUBE USING RIBS OF SEPARATED PORTS ASSEMBLY

The paper deals with numerical investigation for the influence of separated ports assembly ribs on heat transfer ina steel tube of 50 cm long , outside diameter of 60 mm and inside diameter of 30 mm with constant outside surface temperature of 1000, 1200 and 1400 Ko.The renormalization group k-ε model is used to simulate turbulence in ANSYS - FLUENT 14.5. The ribs assembly (5x5 mm triangle passage) were fitted in the tube and separated by 8cm pitch. Results of temperature and velocity distribution along the tube center line for the case of tube with internal ribs were compared with that of plain tube , these results show that the use of internal ribs enhance the heat transfer rate and found to possess the highest performance factors for turbulent flow

Experimental Study of Forced Convection Heat Transfer Porous Media inside a Rectangular Duct at Entrance Region

This work presents experimental investigation of flow and heat transfer characteristics for entry length of turbulent flow in a rectangular duct fitted with porous media and air as the working fluid. Rectangular duct (300×30 mm) with a hydraulic diameter (54.54 mm) was subjected to constant heat flux from lower surface (1.5 ×102 –1.8 ×102 w/m2) and Reynolds number ranged (3.3x104 up to 4.8x104). Copper mesh inserts (as porous media) with screen diameter (54.5 mm) for vary distance between two adjacent screens of (10 mm), (15 mm) and (20 mm) in the porosity range of (0.98 - 0.99) are considered for experimentation. The effect of porous height ratio (full and partial) are also considered. It is observed that the enhancement of heat transfer by using mesh inserts when compared to a plain surface is more by a factor of (2.2) times where the skin fraction coefficient is about (5) times. An Empirical correlation for Nusselt number and friction factor are developed for the mesh inserts from the obtained results

Numerical Investigation of Heat Transfer Enhancement in a Circular Tube with Rectangular Opened Rings

Turbulent forced convection of coolant air flow (10 m/s velocity) in a steel tube of 50 cm long having outside diameter of 60 mm and inside diameter of 30 mm with constant outside surface temperature of 1000, 1200 and 1400 Ko is numerically analyzed. The renormalization group k-ε model is used to simulate turbulence in ANSYS - FLUENT 14.5. An opened ring of rectangular cross section (5x7 mm) is fitted in the tube and separated by 8cm pitch. Results of temperature and velocity distribution along the tube center line for the case of tube with internal ribs were compared with that of plain tube , these results show that the use of internal ribs enhance the heat transfer rate and found to possess the highest performance factors for turbulent flow

EIS examination of mill scale on mild steel with polyester-epoxy powder coating

Abstract Mill scale exists as a thin layer on mild steel. This layer is unstable and cracks easily under mechanical and thermal shocks and this may lead to serious damages in the organic coatings, which have been applied on it. In this study, effects of mill scale removal on performance of a polyester-epoxy powder coating were investigated, using two corrosion test methods: electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) in function of time. These tests were performed in a 3.5% w/w NaCl solution

The Effect of variation Longitudinal Ribs Height in Spanwise Direction on Flow and Heat Transfer Characteristics in a Rectangular Duct

The present work has investigated numerically and experimentally the effect of a streamwise riblet on the flow and heat transfer characteristics for fully developed turbulent flow in a rectangular duct heated with constant heat flux for Reynolds number based on hydraulic diameter range of (1.5×〖10〗^4-6×〖10〗^4). Numerical simulations have been done by solving thegoverning equations (Continuity, Reynolds. Averaging Navier-stokes and Energy) in turbulent regime with appropriate turbulence model Shear-Stress Transport (k-ω) in three dimensions by using the FLUENT version (12.1.2). The variation of peak to peak height of riblet in spanwise direction ratio with 〖(h〗_s⁄h_L =0.5)was simulated. The flow structure and heat transfer characteristics (the velocity contours, vorticity contours, secondary flow contours, temperature contours, the distribution of local wall shear stress and heat transfer coefficient in spanwise direction at ribs)were presented as results. Also the effects of ribs on the flow and heat transfer characteristic at duct were presented, as the percentage of average skin friction, Stanton number and the heat transfer efficiency relative to a smooth surface. Experiments were conducted for rectangular duct of aspect ratio =10. Experimental results indicated an increase in the thickness of hydraulic and thermal sub-layer and shifted up the velocity profile, reducing the skin friction coefficient and Stanton number by about (6 %) and (23%) respectively. The experimental results gave a good agreement with the numerical simulation and previous works

EXPERIMENTAL STUDY ON THE PRESENCE OF OPEN CAVITY EFFECTS ON INTERNAL FLOW AND CONVECTIONHEAT TRANSFER CHARACTERISTICS

An experimental study is conducted to investigate the effect of open cavity on the pattern of fully developed internal flow and convection heat transfer. In this experimental work the velocity profile, temperature distribution, heat transfer coefficient and Nusselt number were determined at various Reynolds numbers (1.9*104≤ Re ≤ 2.7*104 ) for smooth surface as well as for flow over open cavity (with and without excitation). The results showed that the presence of the cavity led to change the downstream velocity profile and the dissimilarity of downstream skin friction coefficient between the upper and lower surfaces around (64 %) at distance to the length cavity (x/L= + 20.5). As a result the heat transfer coefficient and Nu increased downstream of the cavity especially at (x/L= + 20.5) around (30 %). The effect of cavity excitation with different  sound levels (100,107.5 and 115) dB and frequencies (25,50 and 100) Hz was small compared with the cavity itself.

Mitochondrial Regulation of GPX4 Inhibition-Mediated Ferroptosis in Acute Myeloid Leukemia

Resistance to apoptosis in acute myeloid leukemia (AML) cells causes refractory or relapsed disease, associated with dismal clinical outcomes. Ferroptosis, a mode of non-apoptotic cell death triggered by iron-dependent lipid peroxidation, has been investigated as potential therapeutic modality against therapy-resistant cancers, but our knowledge of its role in AML is limited. We investigated ferroptosis in AML cells and identified its mitochondrial regulation as a therapeutic vulnerability. GPX4 knockdown induced ferroptosis in AML cells, accompanied with characteristic mitochondrial lipid peroxidation, exerting anti-AML effects in vitro and in vivo. Electron transport chains (ETC) are primary sources of coenzyme