High CHF Research Articles

Flow boiling in a counter flow straight microchannel pair: LBM study

Heat dissipation of high-power electronics is a critical challenge nowadays. The microchannel heat sinks due to their higher heat removal capability and more uniform temperature distributions are one of the most promising options. Our former experimental studies have shown that the intrinsic shortcomings of microchannels can be improved significantly by an innovative counter flow design of microchannels through the significant channel-to-channel heat transfer mechanism. The current study aims to simulate the flow boiling heat transfer inside a Counter Flow Straight Microchannel (CFSM) pair and compare it with the Co-Current Straight Microchannel (CCSM) one using the MRT-based Pseudopotential model combined with a thermal phase change LB model. The simulation results reveal that the CFSM pair acquires a lower void fraction and demonstrates better heat transfer with a higher CHF than that of CCSM one. The simulation results on CHF for a CCSM pair agree well with the predictions form a well-established correlation in the literature. The simulations quantitatively provide the channel-to-channel heat transfer distribution in the axial direction. The results reveal that better overall heat transfer performance can be achieved with a higher CHF in the CFSM pair by increasing the Reynolds number and inlet subcooling through enhanced channel-to-channel heat transfer.

Nanosecond Laser-Textured Copper Surfaces Hydrophobized with Self-Assembled Monolayers for Enhanced Pool Boiling Heat Transfer.

Increased cooling requirements of many compact systems involving high heat fluxes demand the development of high-performance cooling techniques including immersion cooling utilizing pool boiling. This study presents the functionalization of copper surfaces to create interfaces for enhanced pool boiling heat transfer. Three types of surface structures including a crosshatch pattern, shallow channels and deep channels were developed using nanosecond laser texturing to modify the surface micro- and nanomorphology. Each type of surface structure was tested in the as-prepared superhydrophilic state and superhydrophobic state following hydrophobization, achieved through the application of a nanoscale self-assembled monolayer of a fluorinated silane. Boiling performance evaluation was conducted through three consecutive runs under saturated conditions at atmospheric pressure utilizing water as the coolant. All functionalized surfaces exhibited enhanced boiling heat transfer performance in comparison with an untreated reference. The highest critical heat flux of 1697 kW m-2 was achieved on the hydrophobized surface with shallow channels. The highest heat transfer coefficient of 291.4 kW m-2 K-1 was recorded on the hydrophobized surface with deep channels at CHF incipience, which represents a 775% enhancement over the highest values recorded on the untreated reference. Surface microstructure was identified as the key reason for enhanced heat transfer parameters. Despite large differences in surface wettability, hydrophobized surfaces exhibited comparable (or even higher) CHF values in comparison with their hydrophilic counterparts, which are traditionally considered as more favorable for achieving high CHF values. A significant reduction in bubble departure diameter was observed on the hydrophobized surface with deep channels and is attributed to effective vapor entrapment, which is pointed out as a major contributing reason behind the observed extreme boiling heat transfer performance.

Experimental study on the pool boiling performance of a highly self-dispersion TiO2 nanofluid on copper surface

Enhancing heat transfer performance of pool boiling is attractive in practical applications, while the utilization of nanofluid is regarded as an effective approach. However, existing knowledge of boiling enhancement with nanofluid is still limited in terms of the influences of its type, concentration, deposition and boiling time. In this paper, the pool boiling performance of a highly self-dispersion TiO2 nanofluid with mass concentration from 0.0001% to 0.1% was experimentally investigated and compared with Al2O3 and ZnO nanofluid. The effect of boiling-induced deposition layer was studied by means of repeatability test, wettability test and macro/micro morphology test. Results indicated that a super-hydrophilic micro-porous deposition layer formed on nanofluid boiling surface and led to nearly twice higher CHF than distilled water, and nanofluid itself had negligible influence on CHF enhancement. Increasing concentration of nanofluid led to occasional falling off of the deposition on surface and resulted in complicated and unpredictable boiling performance. Nanofluid type and concentration had limited influence on CHF, whose value kept around 1800 kW/m2. 0.0001% TiO2 and Al2O3 nanofluids had similar boiling curves, but ZnO nanofluid exhibited lower heat transfer coefficient. Finally, a novel criterion to predict the occurrence of film boiling in advance was proposed based on wall superheat change rate threshold. The present study will contribute to design guidance and security control of nanofluid-based pool boiling device.

Alteration of pool boiling heat transfer on metallic surfaces by in situ oxidation

The critical heat flux during pool boiling has been investigated for a range of applications including electrical power generation and thermal management. Reported experimental CHF values during pool boiling of water on flat metallic surfaces, however, show a large discrepancy across studies. Here, we address this discrepancy in CHF values by accounting for oxidation of metallic surfaces during boiling. We studied the effect of in situ oxidation on flat Cu and Ni surfaces by changing the duration that samples were held in saturated water before conducting boiling experiments. The morphology and chemical composition of surfaces after the boiling experiments were analyzed by atomic force microscopy and X-ray photoelectron spectroscopy, respectively. Cu surfaces showed gradually increasing CHF values as the duration in saturated water increased, which could be attributed to the increase in roughness due to the formation of Cu2O nanostructures. Conversely, Ni surfaces showed relatively stable CHF and morphology as a nearly flat layer of NiO formed, with one exception: formation of a highly wetting hydroxide, Ni(OH)2, on a Ni coupon held in saturated water for 24 h resulted in a uniquely high CHF value, signifying the importance of surface chemistry in addition to morphology. The fundamental mechanisms resulting in the wide spread of CHF values on metallic surfaces elucidated in this work will lead to more accurate estimation of CHF as well as a deeper mechanistic understanding of CHF values on engineered surfaces.

Numerical Investigation of Pool Boiling Under Ocean Condition with Lattice Boltzmann Simulation. Part Ⅱ: Rolling Condition

Rolling motion caused by ocean condition will induce more complicated inertial forces with their force directions changing all the time, which results more complex bubble behaviors and unique heat transfer characteristics. In this work, pool boiling under rolling condition is numerically simulated using multiple relaxation time phase change lattice Boltzmann method (LBM). Pool boiling patterns, boiling curve of time-averaged heat flux, transient heat flux and rolling effects on different pool boiling regions are investigated. The results show that pool boiling curve of time-averaged heat flux between rolling condition and static condition are not obvious until close to critical heat flux, and 9.3% higher CHF is achieved under rolling condition while worse heat transfer is discovered at film boiling. Moreover, distinct fluctuation of transient heat flux of pool boiling under rolling condition is found for all boiling regimes, and its variation pattern along with the rolling motion and bubble behavior is investigated. Furthermore, tangential inertial force caused by rolling motion has positive influence on heat transfer of pool boiling, while the centrifugal force has negative influence on heat transfer, since it is opposite to the gravity and hence decreases the buoyancy force. Besides, larger rolling amplitude and smaller rolling period will induce larger additional inertial forces, and thus make greater influences on the bubbles’ behavior and pool boiling heat transfer.

Downregulation of lncRNA-PVT1 participates in the development of progressive chronic kidney disease among patients with congestive heart failure

BackgroundCongestive heart failure (CHF) is a major cause of the development of progressive chronic kidney disease (CKD), while the mechanism is still unknown. LncRNA PVT1 contributes to kidney injury. This study aimed to explore the role of PVT1 in the development of CKD in CHF patients.MethodsExpression of PVT1 in plasma samples of CHF patients with and without CKD was determined by RT-qPCR. The diagnostic value of plasma PVT1 for CKD was evaluated by ROC curve analysis. The predictive value of PVT1 for the development of CKD in CHF patients was analyzed by a 2-year follow-up study. Changes in PVT1 expression in CKD patients during treatment were analyzed by RT-qPCR and reflected by heatmaps.ResultsPlasma PVT1 was downregulated in CHF and further downregulated in CHF patients complicated with progressive CKD. ROC curve analysis showed that plasma PVT1 levels could be used to distinguish CHF patients complicated with CKD from CHF patients without CKD and healthy controls. During a 2-year follow-up, patients with high CHF levels had a low incidence of progressive CKD among CHF patients. Moreover, with the treatment of progressive CKD, plasma PVT1 was upregulated.ConclusionsLncRNA-PVT1 downregulation may participate in the development of progressive CKD among patients with CHF.

CHF enhancement for a finned surface in flow boiling with explanations based on vapor observations

In this study, effects of a finned structure on downward-facing flow boiling were investigated. Compared to a bare surface, a heated surface with a finned structure has a higher CHF and heat transfer coefficient. Two high-speed cameras were utilized to observe boiling behaviors from the downward view and side view. Under low heat flux conditions, there existed a front zone and wake zone due to the existence of the extended heating surface, which was confirmed by a numerical simulation. The bubbles tended to escape from two sides of the extended surface. Under high heat flux conditions, two vapor films formed due to the existence of the finned structure, allowing more water to be supplied to the surface. Meanwhile, the existence of the fin enhanced the turbulence and made the flow field velocity distribution non-uniform, thus enhancing heat transfer and CHF. The maximum vapor film thickness of finned surface was larger than that of the bare surface. A larger maximum volume of vapor generating on the surface suggested a larger amount of latent heat consumption and thus, leading to a bigger CHF. These results demonstrated the potential of CHF enhancement using the finned structure design.

Critical Heat Flux of Confined Round Single Jet and Jet Array Impingement Boiling

This study involves experimental investigation of key parameters influencing CHF for confined round single jets and jet arrays impinging normally onto square heated surfaces. The experiments are performed using R-134a, a fluid widely used for thermal management of electronic and power devices, especially in aerospace applications. A comprehensive R-134a CHF database is acquired that considers the effects of various geometrical parameters and operating conditions. Close examination of the data trends reveals several strategies to augment CHF, such as increasing jet velocity and/or total mass flow rate and employing larger jet diameters for a fixed velocity or smaller diameters for a fixed flow rate. Higher CHF is also achieved by increasing saturation pressure for a fixed inlet fluid temperature (i.e., higher saturation pressures combined with higher inlet subcooling). Fluid exit qualities point to two different CHF mechanisms: subcooled CHF at high flow rates and saturated CHF at low flow rates. Underlying mechanisms are also propounded for two types of CHF transients: a sudden sharp temperature escalation at lower flow rates and a mild gradual increase at higher flow rates. Close inspection of the heating surface following CHF tests shows localized burnout patterns which provide significant insight into both the flow characteristics within the confinement region and the spatial distribution of surface temperature resulting from jet interactions. Statistical inference techniques are used in conjunction with the new understanding of fluid flow and heat transfer physics to formulate a new correlation form for CHF. The resulting correlation, which is based on a consolidated database of the present R-134a and previous FC-72 data, shows good prediction accuracy, evidenced by a mean absolute error of 16.66% for both fluids and over broad ranges of geometrical parameters and operating conditions.

Dry spot dynamics and wet area fractions in pool boiling on micro-pillar and micro-cavity hydrophilic heaters: A 3D lattice Boltzmann phase-change study

A three-dimensional lattice Boltzmann phase-change study is carried out on dry spot characteristics in pool boiling on micro-pillar and micro-cavity hydrophilic heaters under constant bottom wall temperature conditions. The degree of superheat and geometry of these micro-structures (i.e., the pitch distance p, the height h, and the width d) are found to have significant effects on the cycle-average dry spot diameter. Pool boiling curves for these micro-structured heaters are obtained, which are compared with a smooth surface under same conditions. The micro-pillar structured hydrophilic heater is found to have the highest CHF because of capillary wicking, and geometric effects (p/d and h/d) on pool boiling curves from micro-pillar structured hydrophilic heaters are investigated. Although p/d and h/d have small effects on the developing nucleate boiling regime in pool boiling, these parameters have significant effects from fully-developed nucleate boiling to CHF and in transition boiling regime. Critical heat fluxes are shown to be related to wet area fractions: the higher is the wet area fraction, the higher is the CHF.

Performance of batch solid state fermentation for hydrogen production using ground wheat residue

Ground wheat (21 g) was subjected to batch solid state dark fermentation for bio-hydrogen production. Clostridium acetobutylicum (B-527) was used as the culture of dark fermentation bacteria at mesophilic conditions. Effects of moisture content on the rate and yield of bio-hydrogen formation were investigated. The highest CHF (1222 ml), hydrogen yield (63 ml H2 g−1 starch), formation rate (10.64 ml H2 g−1 starch h−1) and specific hydrogen formation rate (0.28 ml H2 g−1 biomass h−1) were obtained with a moisture content of 80%. Nearly complete starch hydrolysis and glucose fermentation were achieved with more than 80% moisture content and the highest substrate conversion rate (21.9 mg L−1 h−1) was obtained with 90% moisture content at batch solid state fermentation producing volatile fatty acids (VFA) and H2.

Polymorphism regulation in Poly(hexamethylene succinate-co-hexamethylene fumarate): Altering the hydrogen bonds in crystalline lattice

Poly(hexamethylene succinate-co-hexamethylene fumarate)s (PHSF) with low hexamethylene fumarate content (CHF, between 0 and 18 mol%) were prepared and employed to explore the effect of intersegmental interaction in crystalline lattice on the polymorphism phenomenon. Wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) results demonstrate that the crystal modification of PHSF exhibits not only CHF-dependent but also crystallization temperature (Tc) dependent. Both high CHF and high Tc benefit the formation of orthorhombic modification, while low CHF and low Tc benefit the formation of monoclinic modification. More intriguingly, the specific “CCCO⋯HCC” hydrogen bonds formed between fumaryl units provide a direct way to regulate the polymorphism from perspective inside chain structure. When CHF is between 8 and 12 mol%, the crystal modification of PHSF is determined by formation of intersegmental hydrogen bonding interaction or not through varying Tc. At high Tc, the specific hydrogen bonds form and render the formation of orthorhombic crystal; while at low Tc, only van der Waals forces remain and PHSF chains crystallize into monoclinic crystal. The content of carbonyl group belonging to fumaryl in polyester chain is a key factor for the formation of hydrogen bonds and the selection of crystal structure during crystallization. Additionally, the orthorhombic crystal shows higher equilibrium melting point than monoclinic crystal; and the monoclinic crystal can transform to orthorhombic crystal by annealing, revealing that orthorhombic crystal is more thermally stable.

Study of High Density Lipoprotein Cholesterol among Patients with Acute Coronary Syndrome in Sohag niversity Hospital

Objective: To estimate the prevalence, and impact of high-density lipoprotein cholesterol (HDL-C) on in-hospital outcomes among acute coronary syndrome (ACS) patients in Sohag University Hospital. Methods: Data were collected prospectively from 273 consecutive patients admitted with a diagnosis of ACS. A low HDL-C was defined as a level <40 mg/dL (1.0 mmol/L) for males and <50 mg/dL (1.3 mmol/L) for females and satisfactory HDL-C is defined as a level ≥40mg/dl for males and ≥50mg/dl for females. Results: The overall mean age of the study patients was 58.9_+11.3 years and majority was males (51.4%). The overall prevalence of low HDL-C was 73.3% and satisfactory HDL-C was 26.7%. During in-hospital stay and at discharge, the majority were on statin therapy (83.2%) while 7.7% were on fibrates. Low HDL-C patients were associated with higher in-hospital mortality than satisfactory HDL-C patients (12% vs. 11%; p=0.012) and higher CHF (18% vs.5.5%; p=0.01). Conclusion: ACS patients in Sohag governorate in upper Egypt have a high prevalence of low HDL-C. Insignificantly higher in-hospital mortality and CHF were associated with low HDL-C in women but not in men.

실리콘 표면 위에 소수성 점을 이용한 비등 열전달 증진에 관한 실험적 연구

Wettability is important to enhance not only CHF but also nucleate boiling heat transfer, as shown by the results of different kinds of boiling experiments. In this regard, an excellent boiling performance (a high CHF and heat transfer performance) could be achieved in the case of pool boiling by some favorable surface modifications that can satisfy the optimized wettability condition. To determine the optimized boiling condition, we design special heaters to examine how two materials, which have different wettabilities (e.g., hydrophilic and hydrophobic materials), affect the boiling phenomena. The special heaters have hydrophobic dots on a hydrophilic surface. The contact angle of the hydrophobic surface is to water at the room temperature. The contact angle of the hydrophilic surface is at same conditions. Experiments involving micro hydrophobic dots and two types of milli hydrophobic dots are performed, and the results are compared with a reference surface.

Photo-fermentative hydrogen gas production from dark fermentation effluent of ground wheat solution: Effects of light source and light intensity

Dark fermentation effluent of wheat powder solution was subjected to light fermentation for bio-hydrogen production using different light sources and intensities. Tungsten, fluorescent, infrared (IR), halogen lamps were used as light sources with a light intensity of 270 Wm −2 along with sunlight. Pure culture of Rhodobacter sphaeroides-RV was used in batch light fermentation experiments. Halogen lamp was found to be the most suitable light source yielding the highest cumulative hydrogen formation (CHF, 252 ml) and yield (781 ml H 2 g −1 TVFA). In the second set of experiments, light fermentations were performed at different light intensities (1–10 klux) using halogen lamp. The optimum light intensity was found to be 5 klux (approx. 176 Wm −2) resulting in the highest CHF (88 ml) and hydrogen yield (1037 ml H 2 g −1TVFA). Hydrogen formation was limited by the availability of light at low light intensities below 5 klux and was inhibited by the excess light above 5 klux.

The Degree of Natriuretic Peptide System Activation in Stable and High Risk Chf Characterized by Increased Cystatin C Is Not Reflected in cGMP Activation

Background Cardiorenal syndrome (CRS) is characterized by neurohumoral activation, sodium retention, ventricular dysfunction and congestion, and renal insufficiency (RI). The congestive heart failure (CHF) component evolves from asymptomatic, to stable symptomatic to overt symptomatic CHF. The natriuretic peptide system (NPS), including atrial (ANP) and brain (BNP) natriuretic peptides is progressively activated during progression of CHF. Less is known about the second messenger, cGMP, of the NPS across the spectrum of CHF. RI in CHF remains an important clinical challenge and Cystatin C is emerging as an important marker of RI. Further work is needed in characterizing Cystatin C across the spectrum of CHF and CRS.

Effects of jet pattern on two-phase performance of hybrid micro-channel/micro-circular-jet-impingement thermal management scheme

This paper explores the two-phase cooling performance of a hybrid cooling scheme in which a linear array of micro-jets deposits liquid gradually along each channel of a micro-channel heat sink. The study also examines the benefits of utilizing differently sized jets along the micro-channel. Three micro-jet patterns, decreasing-jet-size (relative to center of channel), equal-jet-size and increasing-jet-size, were tested using HFE 7100 as working fluid. It is shown feeding subcooled coolant into the micro-channel in a gradual manner greatly reduces vapor growth along the micro-channel. Void fraction increased between jets but decreased sharply beneath each jet, creating a repeated pattern of growth followed by coalesce, and netting only a mild overall increase in void fraction along the flow direction with predominantly liquid flow at outlet. Unlike most flow boiling situations, where pressure drop increases with increasing heat flux, pressure drop in the hybrid configurations actually decreased and reached a minimum just before CHF. This behavior is closely related to the low void fraction and predominantly liquid flow. Pressure drop in the two-phase region is highest for the equal-jet-size pattern, followed by the decreasing-jet-size and increasing-jet-size patterns, respectively. Low void fraction increased the effectiveness of the hybrid cooling schemes in utilizing bulk liquid subcooling and therefore helped achieve high CHF values. The decreasing-jet-size pattern, which had the highest outlet subcooling, achieved the highest CHF. A single correlation was constructed for the three jet patterns, which relates the two-phase heat transfer coefficient to heat flux and wall superheat.

Constructal tree-shaped microchannel networks for maximizing the saturated critical heat flux

A constructal tree-shaped microchannel network for maximizing the saturated critical heat flux in a disc-shaped planar body has been investigated. n 0 radial channels touch the center and n p channels touch the periphery. Designs with no pairing level ( n 0 = n p ), one pairing level ( 2 n 0 = n p ) and two pairing levels ( 4 n 0 = n p ) have been studied. The fluid simulated is R-134a at a saturation temperature of T sat = 30 °C with no inlet subcooling. The flow enters at the center and exits at the periphery. The theoretical CHF model of Revellin and Thome [R. Revellin, J.R. Thome, A theoretical model for the prediction of the critical heat flux in heated microchannels, Int. J. Heat Mass Transfer 51 (2008) 1216–1225], specially developed for micro and minichannels, has been modified and used for predicting the wall CHF of low pressure refrigerants flowing in microchannels. The constraints are the disc radius R and the total volume of ducts V. The degrees of freedom are n 0 , n p and the mass flow rate m ˙ . In each case, the minimum global fluid flow resistance design has been adopted as proposed by Wechsatol et al. [W. Wechsatol, S. Lorente, A. Bejan, Optimal tree-shaped networks for fluid flow in a disc-shaped body, Int. J. Heat Mass Transfer 45 (2002) 4911–4924]. Maximizing the base CHF means increasing the number of central tubes for a given complexity. Furthermore, it is better to use a simple radial structure (with no pairing level) and 2 n 0 central tubes than a design with one pairing level and n 0 central tubes. On one hand, simplified structures seem to be roughly better for maximizing the base CHF. On the other hand, coupling the base CHF and the pumping power leads to different conclusions. There exists an optimal n 0 and n p to maximize the base CHF for each range of pumping power. For instance, for low pumping power, using radial ducts without pairing level is the best solution for dissipating high base CHF whereas for higher pumping power, a more complex design is beneficial with greater n p . In conclusion, the recommended complexity is modest (not maximal), and high complexity is not necessarily the best solution.

The effect of Piboserod a 5-HT4-receptor antagonist on left ventricular function in patients with symptomatic heart failure

Standard therapy: ACEI, diuretics, cardiac glycosides, β-blockers. All patients underwent a 6-min test; evaluation of EF (echoCG); measurement of CRP in blood (EIA method); endotoxin (LAL); faeces plating on growth media; colonoscopy with fecal biopsy with subsequent histological and histochemical (OLA, Muc5, staining for CD8+ cells; Ki67) evaluation of tissue samples at 1 and 14 day of treatment. Results: At first day patients of both groups had plethoric blood vessels in the mucosal proper lamina and focal, dense lymphoid cellular infiltration corresponding to the picture of pronounced chronic inflammation. Lymphocytes were represented primarily by CD8+ cells. Also the number of mucin 5-producing glandular cells was increased. In addition, histological examination revealed abundant siderophages indicating a chronic congestive process in large intestinal blood vessels. At 1 group on 14 day – we found decreasing of chronic inflammation and edema of mucosal proper lamina. In group 2 decreasing of edema was significantly less and increasing of chronic inflammation was finding. Analyses of blood revealed significant (p<0.05) differences between two groups at 14 day: CRP 1.89±0.03 U/l and endotoxin 0.39±0.01 EU/ml in group 1 and CRP 4.6±0.07 U/l and endotoxin 1.3±0.08 EU/ml in group 2. No significant changes in faecal level of enterobacteria were finding. Conclusions: Patients with high FC CHF have chronic inflammation of large intestine, which is probably one of causes for the increased blood endotoxin and development of systemic inflammation. Additional prescription of diuretics, especially diacarb may be helpful in treatment of systemic inflammation in patients with high FC CHF.

Studies on a cooling of high heat flux surface in fusion reactor by impinging planar jet flow

Divertor surface of a fusion reactor is exposed to strong surface heating by high flux charged particles. According to typical design of ITER, the heat flux on divertor surface becomes locally near 20 MW m −2. Then, it is necessary to establish a cooling method to cool such high heat flux surface. A cooling by a planar impinging jet has been proposed. However, in the application of the impinging jet cooling to flat heated surface, high CHF is obtained in the limited region near center. As apart from the region, CHF decreases abruptly with a distance from the center. To overcome this difficulty, we proposed that an impinging planar jet was applied to a concave heated wall where a flow induced centrifugal force acts effectively along the curved surface. In a previous paper, we investigated the CHF for a free planer jet on the concave surface. In this study, CHFs in a confined planar jet, were investigated as a function of distance from the center in the various subcooling, flow velocity and curvature of cooling surface and compared with the CHF in the free planar jet cooling. To investigate CHF in the abnormal condition like mild plasma disruption, CHFs in the transient power input were investigated and discussed in comparison with the steady state CHF. Finally application by both impinging planar jets to the divertor surface are discussed.

Electrodissolution of Ti and p-Si in acidic fluoride media: formation ratio of oxide layers from electrochemical impedance spectroscopy

The electrodissolution of Ti and p-Si electrodes in acidic fluoride solutions has been investigated by electrochemical impedance spectroscopy as a function of potential E, fluoride concentration, pH and angular speed of the electrode, with the aim of characterising the oxide layers covering both materials. The impedance diagrams have been analysed to obtain the low frequency capacitance Clf, the high frequency capacitance Chf and the product RhfI (where Rhf is the high frequency resistance and I the steady-state current). In the potential domain where the oxide thickness x is proportional to E, the formation ratio dx/dE has been computed from Clf, Chf and RhfI. The calculated values have been found to be in good mutual agreement and close to the ones found in the literature.