Determination Of Transfer Coefficient Research Articles

Urban air PCDD/Fs: Dry deposition fluxes and mass transfer coefficients determined using a water surface sampler

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) cause significant environmental concerns. Atmospheric PCDD/Fs permeate water bodies and other ecosystems through wet and dry deposition. In an urban site, dry deposition flux samples of gaseous phase PCDD/Fs were collected by a water surface sampler (WSS) operated between June 2022 and June 2023. There is a conspicuous absence of literature on the direct measurement of dry deposition flux levels in the gaseous phase of PCDD/Fs. In the study, PCDD/Fs in the gas phase reaching the WSS dissolved in the water according to Henry's Law. The PCDD/Fs in the water were transferred to an XAD-2 resin column, sorbing the dissolved PCDD/Fs. The average monthly gas phase dry deposition flux was 34.07 ± 9.35 pg/m2-day (7.35 ± 2.16 pg I-TEQ/m2-day). The highest flux was measured in March (49.53 pg/m2-day), and the lowest was in August (18.64 pg/m2-day). These values indicated the direct flux from air to water. The atmospheric concentration of the gas-phase ranged from 68.38 to 126.88 fg/m3 (13.22–25.01 fg I-TEQ/m3). Dry deposition fluxes and concentrations of atmospheric PCDD/Fs were bigger in the colder months than in the warmer months. This was probably due to a significant increase in residential heating during the colder months, decreased photochemical reactions, and lower mixing heights. Regarding congeners in the dry deposition flux and concentration values in I-TEQ units, 2,3,7,8-TCDD compound predominated with the proportions of 31.61 ± 7.76% and 29.09 ± 12.34%, respectively. Concurrently measured dry deposition flux (Fg) and ambient air concentration (Cg) of PCDD/Fs were considered in the determination of mass transfer coefficient (MTC = Fg/Cg) calculation for each PCDD/F congener. The average MTC for targeted 17 PCDD/Fs was 0.45 ± 0.15 cm/s, and it fluctuated between 0.89 ± 0.30 cm/s for 2,3,7,8-TCDF and 0.2 ± 0.16 cm/s for OCDD.

A new approach for heat transfer coefficient determination in triply periodic minimal surface-based heat exchangers

The development of additive manufacturing offers increasing opportunities in heat transfer. A wider range of materials is used in the 3D printing process of heat exchangers based on the Triply Periodic Minimal Surface. Due to the complexity of these structures, it is difficult to precisely determine the values describing the heat transfer process in these devices. One of the parameters describing the heat transfer process in heat exchangers is the heat transfer coefficient. This study describes a new method for determining the heat transfer coefficient in a heat exchanger based on a gyroidal lattice. The proposed new method allows for determining the heat transfer coefficient values without interfering with the internal space of the compact heat exchanger. The developed formula can be used in the indirect method of determining the value of the heat transfer coefficient in two-phase flow with boiling or condensation of the working medium. The thermal tests were carried out in the range of working flow rates 4–24 kg/h; the media temperature was 20 and 50 °C, the heat flux was from 0.1 to 0.4 kW. Tests were conducted for laminar flow in the 20 < Re < 200 range.

Establishment of Colburn ‘j’ factor and Fanning friction factor ‘f’ correlations for a compact heat exchanger having perforated wavy fins using Computational Fluid Dynamics

Wavy fins find widespread application in compact heat exchangers, due to their ability to achieve high heat transfer coefficients and lower friction factors, resulting in reduced pumping power requirements and improved overall efficiency. Despite the extensive literature available on these fins, no previous study has explored the influence of perforations on wavy fins. This study aims to establish accurate correlations for evaluating the Colburn ‘j’ factor and Fanning friction factor ‘f’ in wavy fins incorporating perforations, specifically tailored for compact heat exchangers. The Colburn ‘j’ factor guides the determination of the heat transfer coefficient, while the Fanning friction factor ‘f’ is instrumental in assessing pressure drop across the fin, both essential considerations in the rating and sizing of compact heat exchangers. The numerical model involves a perforated wavy fin constructed from ‘aluminum’ with ‘air’ as the fluid medium. To derive correlations, 1458 cases were simulated using ANSYS Fluent, systematically varying geometric parameters such as fin height (h), fin spacing (s), fin thickness (t), hole diameter (d), and fin pitch (p). The study spans Reynolds numbers from laminar (200≤Re≤1500) to turbulent (2000≤Re≤10000). ‘j’ &‘f’ factor values were validated using experimental data for wavy fins without perforations, followed by additional analysis incorporating perforations. The analysis showed a 19%–35% increase in the ‘j’ factor and a 21%–33% increase in the ‘f’ factor for perforated wavy fins compared to plain wavy fins. New ‘j’ and ‘f’ factor correlations were established, with over 96.3% and 95.0% of the points within ±16% and ±18% bounds, respectively. These innovative correlations applicable across the entire spectrum of operating and design conditions are expected to facilitate a more streamlined design process for compact heat exchangers featuring this unique fin geometry, enabling designers to reduce iterations during the design phase.

Determination of Carbon Potential and Carbon Mass Transfer Coefficient During Vacuum Carburizing of Steel

Determination of Carbon Potential and Carbon Mass Transfer Coefficient During Vacuum Carburizing of Steel

Effect of temperature sampling methods on sphere packed tube heat transfer coefficient determination

This paper investigates the heat transfer characteristics and the pressure drop of a sphere packed tube using Computational Fluid Dynamics (CFD) simulation. The turbulent kinetic energy of the fluid exhibits significant variation based on the differing accumulation structures of the particles, which is deemed to greatly influence the heat transfer characteristics. Consequently, the temperature distribution at the outer wall becomes inhomogeneous. Previous studies have overlooked the relative positioning between the thermocouples and the particles, potentially leading to inaccurate estimations of the heat transfer coefficient and discrepancies between CFD simulations and real-world experiments. To address this, two temperature sampling methods are employed in this paper to estimate the heat transfer coefficients: one method involves measuring the temperatures at various sampling positions, while the other uses the surface average temperature of the packed area as the sample temperature. Interestingly, it is found that different temperature sampling methods significantly impact the heat transfer coefficients. This study serves as a reminder for future research on sphere packed tubes to prioritize temperature sampling positions.

A High-Resolution Method for the Experimental Determination of the Heat Transfer Coefficients of Industrial Nozzle Systems in Heat Treatment Plants

In industrial plants, metal strips are quenched using convective heat transfer. This involves accelerating gas through a nozzle system onto the material to be quenched, resulting in a fast and uniform cooling process. The efficiency of the heat transfer is determined by the specific nozzle system. The presented work is focussed on the analysis of the heat transfer by forced convection through impingement jets both theoretically and experimentally. A unique method for determining the forced convective heat transfer coefficient is described and its application to industrial size nozzle arrays of annealing-line cooling sections is presented.

Preparation of FeNiCoCrCu Thin Films by Ionized Jet Deposition Method: Determination of Elemental Transfer Coefficients

Investigation of high-entropy alloys in form of bulk samples as well as thin films is currently one of the fastest growing areas in the study of metal alloys. In this paper, a bulk sample of FeNiCoCuCr high-entropy alloy ingot with equimolar composition is prepared by the laboratory arc melting method under an argon atmosphere and used as a source target for deposition of thin films on Si (111) single-crystalline substrates using a novel ionized jet deposition method. The morphology, chemical composition, and real crystalline structure of the target and the prepared layers were characterized by scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and X-ray and neutron diffraction methods. Transfer coefficients characterizing the mass transport between the target and the grown film were calculated for each of the constituting metallic elements as the ratio of the atomic concentration found in the prepared film divided by its concentration in the deposition target. The dependence of the obtained transfer coefficients on the IJD acceleration voltage is discussed with respect to the main physical and geometric parameters of the deposition process, and their correlations with the cohesive energy of the elements forming the HEA are proposed.

Determination of the heat transfer coefficient between pellets and air during the modernization of a pelletizing tower based on industrial research

The object of research is the heat transfer coefficient between pellets and air flow in industrial granulation towers. The problem lies in the difficulty of optimizing the heat transfer process. As a result of experiments and analysis, it was shown that each granulating tower for the production of mineral fertilizers has unique properties that significantly affect the efficiency of heat transfer. There are general mathematical models, but for accurate modeling and optimization of heat transfer, the unique characteristics of each production must be taken into account. The results showed that creating an accurate mathematical model for each specific fertilizer production is a difficult task due to the large number of unmeasured or difficult to reconcile factors. The method of calculating the heat transfer coefficient for the granulator tower obtained in the course of the work derives from a set of researches on the production of mineral fertilizers. This approach is based on the analysis of technical parameters and granulation composition of the product. The developed method makes it possible to reliably ensure the operating conditions of the device during modernization and changes in production volumes. These results are important for both practical and theoretical purposes. They can be used to accurately predict the operating conditions of equipment during modification and productivity growth. According to the research results, this approach allows obtaining fairly reliable data for forecasting the thermodynamic conditions of the tower equipment in the event of its modernization and transition of the granulation tower to the production of an increased amount of products. The specified method was tested in calculations of production modernization at urea production plants (Indian Farmers Fertilizer Cooperative (Iffco), India), Rustavi Azot LLC (Georgia), Grodno Azot LLC (Republic of Belarus) and others. This method has proven to be quite reliable in predicting the possible need for an additional amount of air supplied to the tower and forming requirements for the operating parameters of rotary vibrating granulators in the event of a significant increase in the load on the float in the tower and an increase in the amount of products planned for release.

ANALYSIS OF CALCULATION AND EXPERIMENTAL METHODS OF DETERMINING HEAT LOSSES THROUGH WINDOW CONSTRUCTION

Problem statement. Energy conservation in the conditions of deficit and constant growth in the cost of energy carriers is the main task of the housing and communal complex. Along with the use of energy-saving equipment in life support systems, a significant reduction in energy consumption can be achieved by introducing energy-efficient structural solutions into construction. Translucent structures are considered more unprotected, since heat losses through them can reach 54 % of the total, so they require new approaches to determining heat transfer coefficients. On the basis of the analysis of heat and mass transfer processes element by element for window blocks of non-standard shape, a correct estimate of the heat transfer coefficient was made. The purpose of the article on the basis of the analysis of the thermophysical processes formation through translucent enclosing structures, improve the dependences for calculating the heat transfer coefficient of double-glazed structures taking into acount the climatic load and establishing the relationship between their main thermotechnical characteristics. Results. Based on the analysis of thermophysical processes occurring in opaque structures, the dependence of the heat transfer coefficient of non-standard shape window block on the wind speed, taking into acount the orientation of the building height in the element-by-element determination, was obtained. The main factors affecting the value of the heat transfer coefficient of the window unit have been established, i. e., these dependencies can be used to evaluate energy-saving measures during an energy audit. Scientific novelty and practical value. Dependencies for determining the heat transfer coefficient of translucent structures, taking into acount heat loss through window frames, the location of the window in the wall opening, and structural solutions are obtained. An analysis of the results of heat transfer coefficients for windows of non-standard shape, which are aimed at choosing the optimal technical solutions of wine blocks from the standpoint of energy and resource saving, taking into acount climatic parameters, was conducted. Quantitative results of the radiant and convective components for the element-by-element determination of the heat transfer coefficient of window blocks and heat losses through them are obtained, allowing to establish the priority of energy-saving measures.

A roadmap to estimating agricultural ammonia volatilization over Europe using satellite observations and simulation data

Abstract. Ammonia (NH3) is one of the most important gases emitted from agricultural practices. It affects air quality and the overall climate and is in turn influenced by long-term climate trends as well as by short-term fluctuations in local and regional meteorology. Previous studies have established the capability of the Infrared Atmospheric Sounding Interferometer (IASI) series of instruments, aboard the Metop satellites, to measure ammonia from space since 2007. In this study, we explore the interactions between atmospheric ammonia, land and meteorological variability, and long-term climate trends in Europe. We investigate the emission potential (Γsoil) of ammonia from the soil, which describes the soil–atmosphere ammonia exchange. Γsoil is generally calculated in-field or in laboratory experiments; here, and for the first time, we investigate a method which assesses it remotely using satellite data, reanalysis data products, and model simulations. We focus on ammonia emission potential in March 2011, which marks the start of growing season in Europe. Our results show that Γsoil ranges from 2 × 103 to 9.5 × 104 (dimensionless) in fertilized cropland, such as in the North European Plain, and is of the order of 10–102 in a non-fertilized soil (e.g., forest and grassland). These results agree with in-field measurements from the literature, suggesting that our method can be used in other seasons and regions in the world. However, some improvements are needed in the determination of mass transfer coefficient k (m s−1), which is a crucial parameter to derive Γsoil. Using a climate model, we estimate the expected increase in ammonia columns by the end of the century based on the increase in skin temperature (Tskin), under two different climate scenarios. Ammonia columns are projected to increase by up to 50 %, particularly in eastern Europe, under the SSP2-4.5 scenario and might even double (increase of 100 %) under the SSP5-8.5 scenario. The increase in skin temperature is responsible for a formation of new hotspots of ammonia in Belarus, Ukraine, Hungary, Moldova, parts of Romania, and Switzerland.

Expressing variable mass transfer coefficients for gas fermentation in trickle bed reactor

Gasification of lignocellulosic biomass and syngas biomethanation are promising technologies for producing biomethane. Trickle bed reactors (TBR) are efficient for syngas fermentation allowing for higher concentration of microbial cells and high surface area for mass transfer. Optimized scaling up and dimensioning of the reactor is crucial when it comes to industrial applications. The first step towards this goal and the scope of the present study is to develop a model able to simulate the mass transfer of gases to the liquid phase as a function of the operating conditions and reactor geometry. Experiments were performed in a lab scale TBR with co-current flow of syngas and water, representing the growth medium, to determine the volumetric mass transfer coefficient (kLa) of each gas compound and its dependence on the flowrate of syngas and water and reactor structural characteristics. The kLa achieved were in the range of 6.18–13.6 hr−1 for H2, 2.6–5.79 hr−1 for CO and 1.53–3.43 hr−1 for CO2. A dimensionless equation was fitted to the experimental data and a model was developed to predict kLa of a specific gas at various gas and liquid flowrates, and reactor configurations. A kinetic model was also developed to simulate the concentrations of syngas in gas phase and liquid phase by applying the kLa values predicted by the dimensionless correlation. Finally, the model was validated using experimental data obtained by mass transfer coefficient determination in pilot scale TBR with pure argon gas and literature data where the predicted kLa had a coefficient of variance of ± 15% and ± 25% respectively within a realistic range of liquid and gas flowrates.

Математичне моделювання пристінної оливної плівки в камері підшипника ГТД

The most preferable result of modeling the flow in the BC is the determination of the heat transfer coefficient to the inner wall. The complexity of solving this problem is due to both the complex geometry of the BC and the presence of a two-phase flow, the structure of which changes from air-droplet in the core to a nearly liquid in the wall oil film. Available research results show that even three-dimensional CFD modeling of such a flow does not completely solve the problem. At the same time, the calculation time is long, and the results require, at a minimum, selective experimental validation. At the same time, it can be considered proven that the main mechanism of heat transfer from the core to the wall region of the BC is related to the radial flow of droplets, and the thermal resistance of the wall oil film has a decisive effect on the value of the internal heat transfer coefficient. It is advisable to model these media on the basis of a two-dimensional problem with the averaging of phase parameters along the axis. Considering the small volume fraction of droplets, the Lagrangian approach can be used to model the two-phase flow in the core of the BC. This allows consideration of not only the polydispersity of the droplets, but also the creation and movement of secondary droplets during the formation of the wall oil film. One of the main problems in the modeling of the wall film is the definition of its flow regime and the corresponding criterion equations for calculating the coefficients of friction and heat transfer. Most of the equations use the longitudinal coordinate of the plate as a geometric parameter and cannot be applied to the bearing chamber. In this study, the possibility of converting the film flow into a flow similar to that occurring in a flat pipe is substantiated. This allows not only to consider the geometric features of the BC, but also to use the corresponding Reynolds numbers and similarity equations for the equivalent flow. Along with the use of a two-layer model for the boundary region and the concept of the analogy of transfer processes, this made it possible to form a mathematical model of the film, which considers all the components that determine the formation, movement, and heat transfer of the wall oil film. In addition, the model does not contain restrictions on the appearance of the parameters transverse profile, which are, for example, for the EWF model of the oil film in ANSYS FLUENT. The obtained results along with the previously developed air-droplet flow model in the core provide a complete two-dimensional model of the gas-liquid flow in the GTE bearing chamber, which allows the main geometric and all mode parameters to be used to determine the heat transfer coefficient to the inner wall of the chamber. Given the short calculation time, the proposed model allows for a detailed investigation of each factor’s contribution and element-by-element identification of the model based on the results of more detailed modeling and by comparing calculated and experimental data.

Methodology for Determining Heat Losses through Translucent Construction

The purpose of this work is to determine the heat transfer coefficient of translucent fences, considering the number of storeys of buildings, climatic factors, such as wind velocity and outdoor temperature. To achieve this goal, the following tasks were solved: analysis of heat transfer in translucent enclosures as a quasi-stationary process; analysis of heat transfer processes in translucent barriers, which are a combination of solid transparent plates and air gaps connected by a frame structure; determination of the heat transfer coefficient on the glass surface depending on climatic factors and the radiant component. The most important result is the empirical dependence of the heat transfer coefficient on the outer surface of the window block on the Reynolds criterion, the dependences for determining the heat transfer coefficient of window blocks are improved, considering climatic parameters. The heat transfer coefficient of the window block as a whole is presented in the form of analytical ratios, considering the location of the building and its height, changes in wind velocity and outdoor temperature. This methodology was tested on the example of a civil administrative building, for which the heat transfer coefficients of window structures of non-standard series were evaluated. The significance of the research results lies in the possibility of using the obtained dependencies to assess the thermal characteristics of window structures of non-standard shapes. The dependences of the heat transfer coefficient on wind speed and outside air temperature given in the paper can be used in the energy audit of buildings.

Rheological behavior and modeling of an ultrafiltration process for Aloe vera

AbstractAloe vera (Aloe barbadensis Miller) is employed as a food supplement containing mucopolysaccharides which contribute to a healthy diet. Aloe vera mucilage is usually obtained through an evaporation process. An alternative process to preserve polysaccharide properties is ultrafiltration (UF), which impedes degradation of the compound by temperature. This work analyses the effect of the UF process on the mechanical and rheological properties of Aloe vera considering the following variables: temperature (T), input feeding rate (V), and transmembrane pressure (ΔPTM). The permeate flux varies according to the operating conditions exhibiting non‐Newtonian effects. The determination of the mass transfer coefficient is based on the analogy of transport phenomena (heat transfer to mass transfer) in non‐Newtonian fluids to obtain the permeate flux. The results show that when the mucilage is fed as a diluted shear‐thinning fluid, the UF efficiency is positively affected. To describe the rheological behavior of the concentrated mucilage, the power law and the Bautista‐Manero‐Puig (BMP) models are used and compared. Results suggest that the BMP model represents better the experimental data of permeate flux as a function of filtrate concentration with respect to the experimentally measured permeate flux.Practical ApplicationsCurrently, the use of Aloe vera mucilage as encapsulating agents, thickeners, emulsifiers, and wall materials is highly appreciated by the food and pharmaceutical industry. This research shows that the concentrate obtained from Aloe vera mucilage by ultrafiltration (UF) preserves its rheological properties, unlike other thermal processes. Results represent an interesting and promising alternative to estimate the properties of Aloe vera using more realistic rheological models with promising applications in the food and pharmaceutical industry. The Aloe vera mucilage increases the health benefits using the mucilage in different concentrations in different industrial processes.

Heat Transfer Coefficient Distribution—A Review of Calculation Methods

Determination of the heat transfer coefficient (HTC) distribution is important during the design and operation of many devices in microelectronics, construction, the car industry, drilling, the power industry and research on nuclear fusion. The first part of the manuscript shows works describing how a change in the coefficient affects the operation of devices. Next, various methods of determining the coefficient are presented. The most common method to determine the HTC is the use of Newton’s law of cooling. If this method cannot be applied directly, there are other methods that can be found in the open literature. They use analytical formulations, the lumped thermal capacity assumption, the 1D unsteady heat conduction equation for a semi-infinite wall, the fin model, energy conservation and the analogy between heat and mass transfer. The HTC distribution can also be calculated by means of computational fluid dynamics (CFD) modelling if all boundary conditions with fluid and solid properties are known. Often, the surface on which the HTC is to be determined is not accessible for any measuring sensors, or their installation might disturb the analysed phenomenon. It also happens that calculations using direct or CFD methods cannot be performed due to the lack of required boundary conditions or sufficiently proven models to analyse the considered physical phenomena. Too long a calculation time needed by CFD tools may also be problematic if the method should be used in the online mode. One way to solve the above problem is to assume an unknown boundary condition and include additional information from the sensors located at a certain distance from the investigated surface. The problem defined in this way can be solved by inverse methods. The aim of the paper is to show the current state of knowledge regarding the importance of the heat transfer coefficient and the variety of methods that can be used for its determination.

Determination of Thermocline Heat Transfer Coefficient by Using CFD Simulation

This article deals with a thermal energy storage system in the form of a water tank with a thermocline. The well-known thermocline phenomenon is modeled using computational fluid dynamics (CFD). However, the reservoir model proposed in this article is zero-dimensional. This is due to the fact that the aim of this article is to build a mathematical model that will be more useful in mathematical models of complex energy systems in which a hot water tank is one of many elements of the system. In such a zero-dimensional mathematical model, the hot water tank will be modeled using equations describing heat transfer, and the thermocline itself will be treated as a heat transfer surface with known dimensions and heat transfer coefficient. A novelty of this paper is that it addresses heat loss across the thermocline as defined in this manner. A CFD model of a thermal storage tank is created, validated with available experimental data, and used to obtain the heat transfer coefficient U. The resulting value is then analyzed quantitatively and qualitatively and the changes in the thickness of the thermocline are accounted for in the equation. The results from this groundbreaking work can be used to analyze heat storage in the form of thermocline water tanks at the level of system modeling, e.g., for the purpose of configuring the structure of other devices and control systems.

Oxygen transfer and hydrodynamic evaluation in a multistage flexible fibre biofilm reactor

In present work, the hydrodynamic studies and determination of oxygen mass transfer coefficients (KLa) were conducted in a multistage flexible fibre biofilm reactor developed for treating milk processing wastewater. In this regard, the residence time distributions in the MS-FFBR under various operating conditions as water flow rates, airflow rates, and hydraulic retention times were analysed using tracer experiments. The results revealed that the reactor’s hydraulic regime is similar to a continuous stirred tank reactor. Furthermore, the multistage flexible fibre biofilm reactor exhibited a lower oxygen mass transfer coefficient (KLa of 11.955 1/h at AFR/WFR of 47) than that reported for continuous stirred tank reactor in the literature at similar WFRs and AFRs (KLa of 15 1/h at AFR/WFR of 40). From the results, dissolved oxygen transfer was hindered to some extent owing to the presence of the fibre packing.

Determination of mass transfer coefficient of CO2 removal in water-in-oil emulsion

The removal of carbon dioxide is an important process in natural gas purification since its lower down the calorific value of the natural gas. In addition, carbon dioxide also capable of forming corrosion in the pipeline, thus its removal is crucial. Water-in-oil emulsion was proposed in this research since the absorption of carbon dioxide in emulsion would be an effective method to prevent corrosion. However, the absorption capability of the emulsion and the mass transfer coefficient of carbon dioxide during absorption process needs further investigation. The aim of this study is to determine the diffusivity and mass transfer coefficient of carbon dioxide in the emulsion and observed the correlation between mass transfer coefficient and the carbon dioxide absorption values obtained from experiment. In this study, water-in-oil emulsion was prepared by mixing the aqueous phase and organic phase solutions under two different formulation conditions. Firstly, the methyldiethanolamine (MDEA) and 2 amino-2-methyl-1-propanol (AMP) blending was mixed in different alkaline solution; sodium hydroxide (NaOH) solution, potassium hydroxide (KOH) solution and distilled water (H2O) to form aqueous phase solution. Secondly, MDEA was combined with different alkanolamines; dimethylethanolamine (DMEA), diethanolamine (DEA) and triethanolamine (TEA) in KOH solution to form another aqueous phase solution. The synthesized aqueous phase is then mixed with the organic phase consists of kerosene and Span-80 mixtures. Furthermore, viscosity and particle sizes of the emulsions at different emulsion formulations were measured and the diffusivity and mass transfer coefficients of carbon dioxide were calculated. This study showed that, by using suitable emulsion formulation containing MDEA/AMP in KOH solution, the estimated value of diffusivity and mass transfer coefficient of carbon dioxide was 1.0876 × 1010 m2/s and 1.15 × 103 m/s respectively, with viscosity of 261.03 mPa s and particle size of 189.71 nm was achieved. It was found the diffusion coefficient and mass transfer coefficient of carbon dioxide is highly influenced by the characteristics of emulsion such as viscosity and particles sizes.

Determination of the Heat Transfer Coefficient in Mathematical Models of Heat and Mass Transfer

Determination of the Heat Transfer Coefficient in Mathematical Models of Heat and Mass Transfer

Determination of absorption mass transfer coefficients of methane into drilling fluid base oils at elevated pressures

Absorption mass transfer coefficients (kla) of methane into two widely used drilling fluids base oils-internal olefins and diesel were determined at elevated pressure. A laboratory-scale bubble column (0.0254 m diameter and 0.71 m static liquid height) was used to perform the experiments. Ranges of superficial gas velocity (0.0045–0.0491 m/s) and system pressure (0.69–2.07 MPa) were covered. Based on the results, the effects of the varying parameters on kla have been discussed. Based on the observations, an empirical model was developed for the volumetric mass transfer coefficient as a function of superficial gas velocity and density. This correlation fitted well (R2 > 0.98) with the measured kLa values for the investigated range of operating conditions. This study gives new quantitative insights into the absorption kinetics of methane into two drilling fluid base oils, which are important for improving gas influx management with non-aqueous drilling fluids.