Deviation Of Flow Rate Research Articles

Study on the characteristics of pellet movement under different roasting temperature in hopper

Roasting temperature plays an important role in the chemical reaction of vanadium‑titanium magnetite. In order to investigate the effect of roasting temperature on pellet motion characteristics, a non-cohesive and multi-element particle model of discrete element method (DEM) was constructed. On this basis, different diameter pellets (dp = 20.38 mm, 25.02 mm, 29.67 mm, 35.52 mm) with different roasting temperature (298 K ≤ T ≤ 1473 K) were selected to explore the effects on pellet velocity distribution, discharge mass flow rate, wall pressure and average voidage. Our results reveal a large change in the movement characteristics of pellets involving chemical reactions during high-temperature production. The mean voidage is negatively correlated with the diameter. The minimum deviations of pellet velocity distribution and discharge mass flow rate at different roasting temperature were 20.16% and 21%, respectively, and the maximum deviations of wall pressure and average voidage were 63.47% and 7.0%, respectively.

Reference Value of Nasal Peak Inspiratory Flow Rate in Indian Children: A Cross-sectional Study

Introduction: Peak Nasal Inspiratory Flow (PNIF) measurement is a basic, convenient, easy to use and low cost method of determining the nasal airway patency. However, normative data for paediatric population is scarce and not available for Indian children aged 6 to 12 years. Aim: To establish reference value of PNIF in Indian children aged 6 to 12 years of age. Materials and Methods: A descriptive cross-sectional study was conducted between July 2012 and June 2013 in the Himalayan range of east Sikkim district and Sub-Himalayan Terai region of Darjeeling district of West Bengal. Total 1001 children aged 6 to 12 years were selected from 16 schools by simple random sampling. Of these 1001 children, 784 children were enrolled in the study after taking into account inclusion and exclusion criteria. Repeated PNIF measurements were taken from these 784 children. Mean PNIF value was calculated. The effect of age and height on PNIF was studied. The mean and standard deviation of Peak Inhalation Flow Rate (PIFR) are calculated and compared across groups using a one-way ANOVA test. Regression analysis was done to establish an equation of predicting PNIF level based on height for normal children. The analysis was carried out using Statistical Package for Social Sciences (SPSS) version 16 statistical software. An alpha level of 5% was chosen, which means that any p-value less than 0.05 was considered significant. Results: Mean value of PNIF age group; 6-7 years-53.36 L/min, >7-8 years-56.79 L/min, >8-9 years-63.91 L/min, >9-10 years- 69.45 L/min, >10-11years- 80.71 L/min, >11-12 years-85.69 L/ min. PNIF increases with age and height. A simple formula has also been established to calculate mean PNIF at a given height. PNIF or PIFR (L/min)=-52.716+0.945×height in cm. Conclusion: PNIF measurements are possible in children aged six years and older. Age and height also affect PNIF.

Fiber Bragg grating accelerometer-based nonintrusive flow rate measurements and leak detection.

We aim to develop a nonintrusive, reliable, convenient flow rate measurement and leak detection method. The flow rate is known to be related to the vibration excited by the turbulent internal flow, but there exists some scatter in the vibration data at low flow speeds (<2m/s) due to the resolution limits of the sensor. A customized fiber Bragg grating acceleration sensor is designed and applied to measure the low flow rate and detect leakage in the pipeline. Experimental tests show the relationship between the standard deviation of vibration data and flow rate at low velocity is quadratic; the R2 of quadratic curve fitting is 0.990. Moreover, for leak detection, selected features are used as the input of support vector machine classifiers to identify the leak in the pipeline. The results demonstrate that the proposed method achieves a high accuracy of 99.00% to determine the leak state and nonleak state.

Each-Phase Metering with Gas-Liquid Stratified Flow Based on the Multi-Frequency Coriolis Principle

Gas-liquid two-phase flows generally have the characteristics of complex and variable flow patterns and flow rate uncertainty of each phase. The entrainment of gas increases errors of the existing non-separated multiphase metering. A novel metering method based on the multi-frequency Coriolis principle is proposed to solve the above problems. Compared to the conventional Coriolis mass flowmeter, the third-order mode of the measuring tube is used to improve the accuracy of the measurement. The influences of bubble effect and resonance effect on vibration responses in different vibrational modes were studied to determine the deviations of the apparent values of total density and mass flowrate by simulation. Simulation results with a single-frequency Coriolis flowmeter show that the maximum relative deviations of total density and total mass flowrate are −37.3% and −9.3%, respectively. Driven by different frequencies, the same two phase fluid in the measuring tube can have different responses of the primary mode and the higher vibrational modes. The vibrational responses characteristics corresponding to the first-order and third-order modes of measuring tube were selected and analyzed. Combined with advantages of high precision and multi-parameter measurement of traditional single-frequency Coriolis flowmeters, a multi-frequency correction model suitable for stratified flow was proposed. The results show that the corrected total density and mass flow deviations of gas-containing fluid are within ±4% and ±3%, respectively, which are significantly reduced. Corrected flowrate deviations of the gas-phase and liquid-phase are ±9.1% and ±7.2%, correspondingly, which also meet the metering requirements of the wellhead.

Comparison of throttle devices to measure two-phase flowrates of wet gas with extremely-low liquid loading

The online measurement of wet gas with extremely-low liquid loading (Lockhart-Martinelli parameter lower than 0.02) remains a challenge. In this study, three types of throttle devices, Venturi, orifice plate and cone, are compared experimentally with air-water two-phase flow in a horizontal pipe of inner diameter of 50 mm. High-precision correlations are established to measure the gas and liquid flowrates via a single throttle device. Results show that the two-phase mass flow coefficient (K) of the three throttle devices all increase linearly with the liquid densiometric Froude number and the K correlations are established respectively to correct the gas mass flowrate deviation. The pressure loss ratio (δ) for Venturi is sensitive and monotonous to the liquid loading, which contributes to the high accuracy of liquid flowrate measurement. By incorporating the K correlations, both the gas and liquid mass flowrates can be predicted precisely. The relative error of the gas mass flowrate predicted by the Venturi is within ±2.0% at 95% confidence level, and that of the liquid mass flowrate is within ±15% at 90% confidence level.

Water Heating and Operational Mode Switching Effects on the Performance of a Multifunctional Heat Pump

In this study, a multifunctional air and water source heat pump system was developed with a parallel refrigerant piping arrangement, which possessed six operational functions: space cooling (SC), space heating (SH), water heating (WH), water cooling (WC) and two composite operational modes. The two composite operational modes were the SC/WH mode and the SH/WH mode. The performance of the multifuctional heat pump system under different ambient conditions was investigated based on the testing standards of CNS 14464 and CNS 15466. In this study, the effect of the direct water heating (DWH) and circulating water heating (CWH) methods on the performance was investigated. It was found that the water heating performance of the system by the DWH method is better than that of the system by the CWH method. The water heating capacity and COPw,h of the DWH method can be improvement by 2.6% to 22.1% and 2.9% to 50.8%, respectively. Moreover, this study developed a refrigerant pressure balance method to achieve an effective steady state of the refrigerant pressure after operational mode switching. By the refrigerant pressure balance method, the required time to attain the steady state could be greatly reduced—by 50%. However, the deviation of the refrigerant mass flow rate between the refrigerant pressure balance method and the refrigerant pump down method after operational mode switching ranged from 0.15% to 7.6%.

Structure turbulent flow behind a square cylinder with an angle of incidence

This article shows the results of a study of the structure of turbulent flow behind a square profile ALUTEC 45×45mm with T-slots. The angle of rotation of the profile relative to its axis varied α=0°, 15°, 30° and 45°. During the experiment, the flow velocity was 5m⋅s−1, Reynolds number was 7.7⋅104. The Constant Temperature Anemometry technique was used for experimental studies. To avoid backflow, the measuring plane was positioned at the rear of the profile at a distance of x⋅d−1≈2.2. As a result of the studies, it was found that the highest Taylor microscale Reynolds number and standard deviation for turbulent flow was observed in the area behind the cylinder. The width of this area is 3.5 times the width of the cylinder. With the distance from the center of the cylinder in the spanwise direction to flow the Taylor microscale Reynolds number and standard deviation sharply decreases. The maximum values of the Taylor microscale Reynolds number are observed at α=45° is 426 and 398. It has also been found that behind the cylinder there is some area in which the some parameters of the turbulent flow vary greatly with the change angle α. The lowest energy dissipation rate in this range is observed for α=15°−68m2⋅s−3 and the largest for α=0°−138m2⋅s−3. We also found that the minimum value of the Kolmogorov scale and the Kolmogorov time is observed at α=0°. The minimum values of the Kolmogorov scale η=71μm and the Kolmogorov time τη=0.33ms. The maximum values for previous parameters observed at α=15° is η=84μm and τη=0.47ms. We also found that the flow rate and standard deviation distributions between the ALUTEC profile and the ordinary square cylinder different. This can be observed when the upper part of the profile is tightly closed and the lower part is open. In this case, along with the profile inside of the T-slot, there is a generation of internal flow. This reduces the total backflow area behind the ALUTEC profile by 20% compared to an ordinary square profile.

Thermal management of electric vehicle battery cells with homogeneous coolant and temperature distribution

Electric vehicles play an integral role in eliminating pollution related to transportation, especially if the electricity is generated via renewable sources. However, storing electricity onboard requires many battery cells. If the temperature of the cells is not strictly regulated, their capacity decreases in time, and they may burn or explode due to thermal runaway. Battery thermal management systems emerged for safe operations by keeping the battery cell temperatures under limit values. However, the current solutions do not yield uniform temperature distribution for all the cells in a pack. Here, we document that constant temperature distribution can be achieved with uniform coolant distribution to the channels located between batteries. The design process of the developed battery pack begins with a design used in current packs. Later, how the shape of the distributor channel affects flow uniformity is documented. Then, the design complexity was increased to satisfy the flow uniformity condition, which is essential for temperature uniformity. The design was altered based on a constructal design methodology with an iterative exhaustive search approach. The uncovered constructal design yields a uniform coolant distribution with a maximum of 0.81% flow rate deviation along channels. The developed design is palpable and easy to manufacture relative to the tapered manifold designs. The results also document that the peak temperature difference between the cells decreases from a maximum of 12 K to 0.4 K. Furthermore, homogenous distribution of air is one of the limiting factors of the development of metal–air batteries. This paper also documents how air can be distributed uniformly to metal–air battery cells in a battery pack.

Performance of the LDA Volumetric Flow Rate Standard Under Severely Disturbed Flow Conditions

Flow meters in thermal power plants are operated at high temperatures and pressures and often encounter disturbed flow profiles. This leads to an increased measurement uncertainty, limiting the safe operating range of flow rates and thus, the plant's power output. To respond to this shortcoming, the laser optical flow rate standard (LFS) was developed. The LFS is designed to allow the on-site calibration of industrial flow meters in power plants at high temperatures and pressures. It makes use of the laser Doppler anemometry (LDA), as a fundamental and non-invasive method, to measure the velocity field simultaneously with two LDA systems. The volumetric flow rate is then determined by means of integration. Here, we present flow rate measurements for a fully developed pipe flow and for six pipe diameters downstream of a disturbance generator. The mean deviation in flow rate between the two LDA systems was 0.05%, with a mean deviation from the gravimetric reference flow rate of 0.12%. The highest deviations from the reference were 0.21% and 0.31%, for the first and second system respectively.

Improving Feedability of Highly Adhesive Active Pharmaceutical Ingredients by Silication

Loss-in-weight feeders play a vital role in assuring blend and content uniformity as well as lot-to-lot powder traceability in continuous manufacturing. Irregular flow from the feeders propagates through the system, potentially resulting in out-of-specification product. Powder properties such as density, cohesion, and adhesion can cause large variability in the flow rate of ingredients from powder feeders. Feeding of active pharmaceutical ingredients (API) can be difficult because of inherently poor flow, low density, high cohesion, and adhesion. API was chosen due to known adhesion behavior inside feeders during continuous operations. The selected APIs were blended with nanosized silica, in a V-blender, to provide separation between the API particles and reducing the effect of interparticle forces. The material was characterized by standard pharmaceutical techniques to identify bulk changes between the as-received and the blended API. The coated API was then fed using a Coperion K-Tron KT-20 pharmaceutical loss-in-weight feeder. The material was dispensed onto a catch scale, recording mass versus time, and analyzed for relative standard deviation and deviation from the set point. Additionally, the mass of the remaining API in the feeder after the run ended was compared between the API and silica-blended API. Blending APIs with nanosized silica successfully improved API feeding performance despite their intrinsic highly adhesive and cohesive behavior. Both the pure and silica-blended APIs were fed using a twin screw powder feeder. When feeding unsilicated APIs, large variability in flow rate and screw speed were observed, and large amounts of material coated the inside of the hopper and screws. When the adhesive APIs were blended with nanosized silica and fed through a loss-in-weight feeder, there was significantly less adhesion to the feeder, and the material was dispensed with significant reduction in flow rate and screw speed variability. This work provides a means to increase the applicability of continuous manufacturing by enabling the practitioner to manage adverse impact of cohesive material properties on feeder performance. Blending highly adhesive API with silica reduces the adhesion of the API to the feeder hopper and screws, while also improving the deviation in mass flow rate exiting the feeder.

Numerical and Experimental Study of Microchannel Performance on Flow Maldistribution.

Miniaturized heat exchangers are well known for their superior heat transfer capabilities in comparison to macro-scale devices. While in standard microchannel systems the improved performance is provided by miniaturized distances and very small hydraulic diameters, another approach can also be followed, namely, the generation of local turbulences. Localized turbulence enhances the heat exchanger performance in any channel or tube, but also includes an increased pressure loss. Shifting the critical Reynolds number to a lower value by introducing perturbators controls pressure losses and improves thermal efficiency to a considerable extent. The objective of this paper is to investigate in detail collector performance based on reduced-order modelling and validate the numerical model based on experimental observations of flow maldistribution and pressure losses. Two different types of perturbators, Wire-net and S-shape, were analyzed. For the former, a metallic wire mesh was inserted in the flow passages (hot and cold gas flow) to ensure stiffness and enhance microchannel efficiency. The wire-net perturbators were replaced using an S-shaped perturbator model for a comparative study in the second case mentioned above. An optimum mass flow rate could be found when the thermal efficiency reaches a maximum. Investigation of collectors with different microchannel configurations (s-shaped, wire-net and plane channels) showed that mass flow rate deviation decreases with an increase in microchannel resistance. The recirculation zones in the cylindrical collectors also changed the maldistribution pattern. From experiments, it could be observed that microchannels with S-shaped perturbators shifted the onset of turbulent transition to lower Reynolds number values. Experimental studies on pressure losses showed that the pressure losses obtained from numerical studies were in good agreement with the experiments (<4%).

Blood flow quantification in dialysis access using digital subtraction angiography: A retrospective study

Background and objectiveVascular access is the “lifeline” of end-stage renal disease patients, which is surgically constructed to remove blood-waste and return artificially filtered blood into circulation. The arteriovenous shunting causes an abrupt change in blood flow and results in increased fluidic stress, which predisposes to access stenosis and thrombosis. While access flow is crucial to evaluate interventional endpoint, application to measure flow using digital angiogram is not yet available. The goal of this study was to determine the feasibility of flow quantification in dialysis access using a software tool and to guide the design of an imaging protocol. Methods173 digital subtraction angiographic (DSA) images were retrospectively analyzed to evaluate access flow in a custom-programming environment. Four bolus transit time algorithms and a distance calculation method were assessed for flow computation. Gamma variate function was applied to remove secondary flow and intensity outliers in the bolus time-intensity curves and evaluated for enhancement in computational accuracy. The percent deviations of flow rates computed from dilution of iodinated radio-contrast material were compared with in situ catheter-based flow measurement. ResultsAmong the implemented bolus transit time algorithms, quantification error (mean ± standard error) of cross-correlation algorithm without and with gamma variate curve fitting was 35 ± 1% and 22 ± 1%, respectively. All other algorithms had quantification error >27%. The bias and limits of agreement of the cross-correlation algorithm with gamma variate curve fit was −94 ml/min and [−353, 165] mL/min, respectively. ConclusionsThe cross-correlation algorithm with gamma variate curve fit had the best accuracy and reproducibility for image-based blood flow computation. To further enhance accuracy, images may need to be acquired with a dedicated injection protocol with predetermined parameters such as the duration, rate and mode of bolus injection, and the acquisition frame rate.

A Study on Flow Characteristics and Flow Uniformity for the Efficient Design of a Flow Frame in a Redox Flow Battery

As global environmental problems are worsening, the efficiency of storage systems for renewable energy are gaining importance. The redox flow battery (RFB), a promising energy storage system (ESS), is a device that generates or stores electricity through reduction–oxidation reactions between active materials constituting electrolytes. Herein, we proposed a flow frame design that reduces flow resistance in the flow path and causes uniform flow distribution in the electrode to develop an efficient redox flow battery. Through computational fluid dynamics (CFD) and experimental verification, we investigated the flow characteristics and flow uniformity inside the conventional redox flow battery cell. An analysis of the flow characteristics of the conventional flow frame revealed a non-uniform distribution of the flow discharged to the electrodes, owing to the complex (branched) flow path geometry of the inlet channel. To address this problem, we proposed a new flow frame design that removed and integrated bifurcations in the flow path. This new design significantly improved flow uniformity parameters, such as the symmetry coefficient ( C s y m ), variability range coefficient ( R i ), and maximum flow rate deviation ( D m ). Ultimately, we decreased the pressure drop by 15.3% by reducing the number of flow path bifurcations and chevron repositioning.

Analytical solution of linearized equations for transient gas flows in gas pipelines

We consider the new class of high precision simplified linear models of transient high-pressure gas flows along linear sections of pipelines. Representatives of this class are obtained from different initial models defined by partial differential equations. The new models are based on the exact solution of the Klein-Gordon equation, which appears as a result of piecewise linear approximation of nonlinear models in the form of Charny’s equations [1–4] or piecewise constant approximation in models that describe deviations of pressure and mass flow rates from their values in the basic stationary mode [10–13, 16–17]. The new class of models has significant advantages over nonlinear simplified models in optimization problems of large-scale networks, reducing the calculation time by more than two orders of magnitude. They are also free from errors of the approximate inverse Laplace transform or dimensionality reduction techniques traditionally applied in such situations.

Numerical assessment of the critical factors in determining coal seam permeability based on the field data

Accurate acquisition of the coal seam permeability is of great significance to gas drainage. Field measurements are more reliable to determine the coal permeability than laboratory. The Radial Flow Permeability (RFP) measurement is the most used field measuring method to measure the coal seam permeability in Chinese coal mines. The theoretical basis of the RFP method is the single-porosity medium flow theory and the gas content in coal seams is described by a parabolic equation. However, coal is a typical dual-porosity medium. The simplifications may lead to nonnegligible influence on the accuracy of the RFP method, which are not well documented in the literature. In this paper, three different mathematical models of gas flow in coal seams are established. The field gas flow data was matched by these three models to prove the reliability of these models. Then the influences of single-porosity simplification and the parabolic gas content simplification on the accuracy of the RFP method were investigated by comparing the differences of gas flow rates and gas pressures. Results show that there are apparent deviations of gas flow rate and gas pressure between these three models. The precision of the RFP method rapidly reduces with the increase of cleat spacing, which is induced by the single-porosity simplification; the precision decreases with the increase of Langmuir volume, first increases and then declines with the increase of Langmuir pressure, which are led by the gas content simplification. Moreover, because of the imperfections of the numerical calculus in the derivation of the RFP method, the calculated value is always smaller than the true value of coal seam permeability.

Analysis of thermal deviations in L-shape platen superheaters of a supercritical 600 MW circulating fluidized bed boiler

In circulating fluidized bed (CFB) boilers, L-shape platen superheaters often suffer from poor working conditions with a high risk of tube wall overtemperature. Thermal deviations of an L-shape platen superheater were studied by using a supercritical 600 MW CFB boiler as reference. Based on the prediction model of thermal deviations and a self-developed software, thermal deviations of the platen superheater were calculated and analyzed under three kinds of heat load distributions. The results show that the heat absorption deviations for steam are related to the heat load and heating area distribution, wherein the heat load is more effective than the heating area. The mass flow rate deviations for steam mainly depend on the header effect and the nonuniform tube length, while the mass flow rate deviations induced by thermal effects are negligible. The mass flow rates of each tube are nearly identical because the header effect offsets the effect of the nonuniform tube length. Therefore, the heat absorption deviations determine the final thermal deviations of the platen superheater. It is suggested to make complete use of the header effect on the mass flow rate distribution; thus, achieving good control of the thermal deviation of platen superheaters.

Experimental Studies on the Distribution of Air Flows in Air Cooled Steam Condensers

The uniformity degree of the air distribution over the heat-exchange surface of an air cooled condenser (ACC) plays an important role since it determines the efficiency of this surface’s usage. In this paper, this factor at a special stand, where all the main processes of an air flow were simulated, is studied. The typical design of the A-framed ACC was chosen as the basis for the study. Two ACC models differing from one another by the presence of a diffuser after the fan were studied. Each of the models was tested in two versions: with a low-speed electric motor and a high-speed electric motor with a gearbox. In the ACC models, heat transfer surfaces were simulated by a set of flat metal grids with a uniform distribution of square cells. The aerodynamic drag of a set of grids was preliminarily selected so that the Euler criteria were equal for the full-scale object and model. During the tests, the air velocities in front of and behind the grids were measured by traversing, and the velocity fields (isotachs) of the cooling air in these sections were plotted. A condenser with a low-speed electric motor provides the most uniform distribution of cooling air over the heat-exchange surface, while condensers with a high-speed electric motor and gearbox and with a diffuser have significantly greater nonuniformity in the air supply. During the “suction” operation, the flow distribution is more uniform but worse than that for the version with a low-speed electric motor. The effect of the nonuniform velocity field of cooling air on the heat transfer of ACC is estimated. The real condenser module was calculated for various flow and velocity distributions along the tube length. Losses of heat removal due to the nonuniformity of the air flow of the considered circuits can be estimated within 1–3% at a ±50% deviation of the flow rate from the average value.

An analytical study to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system

Based on air flow rate testing of each branch fan in a distributed fan ventilation system under different branch air duct inlet static pressures, the conclusion can be drawn that there is a branch fan air flow rate deviation phenomenon. The air flow rate of the branch fan increases with the branch air duct inlet static pressure at the same branch fan speed, and the branch fan hinders the air flow rate in some cases. In this study, a theoretical expression of the deviation of the branch air duct design air flow rate was established, and the influencing factors of the deviation were determined to include the branch air duct resistance characteristics, branch fan performance, and branch air duct inlet pressure ratio. A graphic analytical method for determining the deviation of the branch fan design air flow rate was also proposed. Both methods can provide a theoretical basis for calculating and analysing the deviation of the branch fan design air flow rate in a distributed fan ventilation system. Practical application: This paper provides new data on the performance of a distributed fan ventilation system. Our results could be used to evaluate the impact of distributed zone fans on the air flow rate in a mechanical ventilation system. Crucially, we not only propose two types of methods that can be applied to predict deviations of the air flow rate in a distributed fan ventilation system caused by the branch air duct inlet static pressures but also obtain the factors that are important for understanding the true impact of the deviation of the branch fan air flow rate. This study lays an important foundation for the design and operation of building mechanical ventilation systems.

Development of a static test apparatus for evaluating the performance of three PM2.5 separators commonly used in China

PM2.5 separator directly affects the accuracy of PM2.5 sampling. The specification testing and evaluation for PM2.5 separator is particularly important, especially under China's wide variation of terrain and climate. In this study, first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM2.5 separators. A uniform mixing chamber was developed to make particles mix completely. The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%, and the particle size distribution obeyed logarithmic normal distribution with an R2 of 0.996. The flow rate deviation between the measurement and the set point flow rate agreed to within ±1.0% in the range of −40 to 50°C. Secondly, the separation, flow and loading characteristics of three cyclone separators (VSCC-A, SCC-A and SCC112) were evaluated using this system. The results showed that the 50% cutoff sizes (D50) of the three cyclones were 2.48, 2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates, respectively. The geometric standard deviation (GSD) of the capture efficiency of VSCC-A was 1.23, showed a slightly sharper than SCC-A (GSD =1.27), while the SCC112 did not meet the relevant indicator (GSD = 1.2 ± 0.1) with a GSD = 1.44. The flow rate and loading test had a great effect on D50, while the GSD remained almost the same as before. In addition, the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.

Numerical Simulation of Capillary Tube for Selected Refrigerants Using Homogeneous Equilibrium Model

In this work, a set of computational investigation results of two-phase refrigerant flow through adiabatic capillary are presented. There are various sizes of capillary tubes that can be selected related to commercially available copper tubes. Earlier refrigerants and new refrigerants like R12, R22, R134a, R410A and R32 are used for the flow analysis. Homogeneous-equilibrium model is employed with user-defined properties of the refrigerants for computation using ANSYS CFX. Several important parameters can be predicted rapidly and accurately using this method such as refrigerant mass flow rate, vapor mass fraction, local Mach no. etc. The mean deviation in mass flow rate is found to be [Formula: see text]1.18% for the same length of capillary tube and the mean deviation of tube length is found to be [Formula: see text]1.48% for the same experimental mass flow rate with choked flow condition.