Correlation For Mass Flow Rate Research Articles

Experimental study on turbulent natural convection of air between the open-ended parallel plates with one-side heating

In the present study, experiments on the turbulent natural convection of air for PAS were carried out. The heat transfer and flow rate induced by buoyancy were investigated. When the heated wall is inclined upward, the heat transfer coefficient increases with the decrease of inclination angle. And the pressure loss along the channel decreases because of the decrease of the velocity gradient. Based on the experimental data, the heat transfer correlation and mass flow rate correlation considering the influence of inclination angle were proposed. And they are applicable to predict the heat transfer and flow rate for PAS. In addition, a criterion for classifying the mixed and natural convection was deduced. The research results can be applied in the analysis of the thermal-hydraulics of the PAS to improve the security of nuclear power plants.

Computational performance analysis of a solar chimney using surface modifications of the absorber plate

Solar chimney technology has received considerable attention in recent years as it offers suitable thermal comfort at the desired space and involves no running cost and harmful emissions. The heat transfer and ventilation performance of the solar chimney greatly depend on the configuration of the absorber plate. Thus, the present paper numerically investigates the effect of variations in geometrical configurations of the wavy absorber plate such as the number of waves, wave amplitude, inclination angle of the chimney, inclination angle of the glass plate, and air gap. The numerical analysis suggested optimum number of waves to be 10 (Nu = 210), optimum inclination of the chimney to be 55° (Nu = 220), and optimum wave amplitude to be 6.25 cm (Nu = 232). However, no optimum values were obtained for variations in glass plate inclination and the air gap. The inverted T plate surface geometry (Nu = 252–257) delivered the highest enhancement in heat transfer performance relative to other surface geometries. Correlations have been developed for the performance parameters by performing several numerical experiments and the proposed mass flow rate correlation predicts 91.3% of the data within ±7%, whereas, the Nusselt number correlation predicts 93.47% of the data within ±7%.

Numerical Simulation on Effects of Horizontal Natural Opening Area and Heat Release Rate on Temperature Distribution and Vent Flow in Small Compartment

In this study, the numerical simulation to investigate the effects of horizontal natural opening areas and heat release rates on temperature distribution and vent flow in a small compartment was performed using a fire dynamics simulator. The reduced scale model of a stage in a real scale theater with horizontal natural opening was selected for this study. The horizontal opening areas were 0.0196, 0.1024, and 0.2025 m<sup>2</sup> (1, 5, and 10% of the floor area, respectively), and the heat release rates were 0.46, 1.35, and 2.61 kW. By decreasing the horizontal opening area and increasing the heat release rate, the temperature in the compartment increased. Additionally, by increasing the heat release rate, the average velocity near the center of the opening increased. For the increase in the horizontal opening area from 0.0196 to 0.1024 m<sup>2</sup>, the velocity near the center of the opening increased. However, when the horizontal opening area increased from 0.1024 to 0.2025 m<sup>2</sup>, the variation in velocity was not noticeable. Considering the analyses of temperature and velocity distributions of vent flow, the bidirectional flow pattern was observed, where the outflow and inflow occurred at the center and edge of the horizontal opening, respectively. The mass flow rate through the horizontal opening increased with the increase in the horizontal opening area and heat release rate. The previous correlation for mass flow rate under-predicted the present numerical simulation data.

Prediction of steady-state two-phase flow of nitrogen + extinguishant in the pipeline and a correlation for mass flow rate

Nitrogen used for pressurization of a fire extinguisher could be partially dissolved in the fire extinguishing agent, forming a binary mixture accompanied by a phase change while flowing inside the pipeline. Notwithstanding the widespread use of fire extinguishing system, few effective methods have been considered to predict two-phase flow performance of nitrogen + extinguishant in the pipeline. This paper presents the study on the performance of the steady-state two-phase flow of extinguishant in the pipeline, including C3HF7 (HFC227ea), CF3I, and C2HF5 (HFC125). The average viscosity of mixture was calculated using six quoted methods (VM-1–VM-6). The corresponding prediction models (STFM-1–STFM-6) for large mass flux nitrogen + extinguishant in a fire extinguishing pipeline were developed based on the VM-1–VM-6. In comparison with previous experimental and theoretical data, the applicability and accuracy of the proposed mathematical models was examined from mass flow rate and pressure drop. The results indicated that both models STFM-2 and STFM-3 could accurately predict for mass flow rate and that STFM-2 could predict for pressure drop. Finally, new correlations for mass flow rate and pressure drop have been established accurately based on the predicted data, respectively. This work contributes to a good theoretical approach on the analysis of two-phase flow of nitrogen + extinguishant.

Numerical investigation on various heat exchanger performances to determine an optimum configuration for charge air cooler, oil and water radiators in F1 sidepods

Abstract The present work focuses on a three-dimensional CFD approach to predict the performance of various heat exchangers in conjunction with non-isothermal transitional flows for motorsport applications. The objective of this study is to determine the heat transfer, pressure drop and inhomogeneous flow behaviour for distinct heat exchangers to identify an optimum configuration for the charge air cooler, water and oil radiators placed in the sidepods of a formula one (F1) car. Therefore, a comprehensive analysis of various heat exchanger configurations has been carried out in this work. In order to assess the reliability of the obtained results, a mesh sensitivity study along with additional parametric investigations have been performed to provide numerical parameters predicting accurately (a) the heat transfer rate at the fluid-solid interface and (b) the sporadic separation. As a result of the performed validation procedure in this study, the aerodynamic- and thermal boundary layer development along with the convective characteristics of the air flow have been captured accurately near to the heated surface. The characterization of a heat exchanger core and a core configuration in a closed domain is also possible with this procedure. The presented three-dimensional CFD approach could overcome the difficulties of macroscopic heat exchanger and porous media methods for F1 applications, because it can be used to predict the heat transfer and pressure drop related to the mass flow rate correlation curves. The contribution of fins to the total heat transfer rate has been predicted theoretically, and application benchmark test cases have been presented to analyze five different heat exchanger configurations in accordance with the 2014 formula one technical regulations. The numerical data extracted directly from three-dimensional CFD simulations can be used in the sidepod design process of the external cooling system of F1 engines.

Taguchi Method for Development of Mass Flow Rate Correlation using Hydrocarbon Refrigerant Mixture in Capillary Tube

The capillary tube is an important control device used in small vapor compression refrigeration systems such as window air-conditioners, household refrigerators and freezers. This paper develops a non-dimensional correlation based on the test results of the adiabatic capillary tube for the mass flow rate through the tube using a hydrocarbon refrigerant mixture of 89.3% propane and 10.7% butane (HCM). The Taguchi method, a statistical experimental design approach, was employed. This approach explores the economic benefit that lies in studies of this nature, where only a small number of experiments are required and yet valid results are obtained. Considering the effects of the capillary tube geometry and the inlet condition of the tube, dimensionless parameters were chosen. The new correlation was also based on the Buckingham Pi theorem. This correlation predicts 86.67% of the present experimental data within a relative deviation of -10% to +10%. The predictions by this correlation were also compared with results in published literature.

Choked flow mechanism of HFC-134a flowing through short-tube orifices

This paper is a continuation of the author’s previous work. New experimental data on the occurrence of choked flow phenomenon and mass flow rate of HFC-134a inside short-tube orifices under choked flow condition are presented. Short-tube orifices diameters ranging from 0.406mm to 0.686mm with lengths ranging from 1mm to 3mm which can be applied to a miniature vapour-compression refrigeration system are examined. The experimental results indicated that the occurrence of choked flow phenomena inside short-tube orifices is different from that obtained from short-tube orifice diameters of greater than 1mm, which are typically used in air-conditioner. The beginning of choked flow is dependent on the downstream pressure, degree of subcooling, and length-to-diameter ratio. Under choked flow condition, the mass flow rate is greatly varied with the short-tube orifice dimension, but it is slightly affected by the operating conditions. A correlation of mass flow rate through short-tube orifices is proposed in terms of the dimensionless parameters. The predicted results show good agreement with experimental data with a mean deviation of 4.69%.

Modification to mass flow rate correlation in oil–water two-phase flow by a V-cone flow meter in consideration of the oil–water viscosity ratio

Oil–water two-phase flow widely exists and its measurement is of significance in oil well logging, oil transportations, etc. One of the techniques in common use in oil–water two-phase flow rate measurement is the differential pressure (DP) meters combining a theoretical model connecting the mass flow rate of the mixture with the differential pressures generated by the throttling element installed inside the pipeline. Though a number of publications focus on DP meters in measuring gas–water two-phase flows or wet gas, the existing models are still not very compatible in oil–water two-phase flow. In this work, a series of oil–water two-phase flow experiments were conducted in a horizontal pipe of 50 mm diameter and the flow rate was measured by a V-cone meter with a diameter ratio of 0.65. Available correlations of DP meters developed from gas–water flow are studied and compared with the measured data from the V-cone meter. A modified correlation is proposed based on the influence of viscosity of oil upon the differential pressure model and three-dimensional computerized fluid dynamic (CFD) simulations. The results have shown that the proposed method achieves better accuracy in oil–water two-phase flow rate measurement than other DP correlations, and it can be extended to other oil–water flow conditions by adjusting the tuning factor.

Mass flow rate correlation for two-phase flow of R218 through a capillary tube

This paper presents some experimental results of refrigerant two-phase flow through a capillary tube. The data was obtained for fluorinert refrigerant R218, which is used in some special vapor cooling circuits, e.g. in various particle detectors at the CERN international research centre. An analytical correlation for mass flow rate of R218 was prepared on the bases of dimensionless parameters derived from the Buckingham π-theorem. Two approaches were compared: (a) the conventional power law function and (b) correlation determined with the use of an artificial neural network. Measured data were also correlated with other mass flow rate correlations presented in literature.

A Mass Flow Rate Correlation for Refrigerants and Refrigerant Mixtures Flowing Through Short Tubes

A correlation was developed to predict the mass flow rate of R-12, R-134a, R-502, R-22, R-407C, and R-410A through short tubes. Short tube lengths ranged from 9.5 mm to 25.4 mm, and sharp edged diameters ranged from 1.09 mm to 1.94 mm. The correlation covered both single-phase and two-phase entrance conditions under approximately choked flow. The correlation consists of nondimensional parameters that are a function of upstream conditions, downstream conditions, short tube geometry, and critical point pressure/temperature. The correlated data were drawn from previous work and work performed during this investigation. The general form of the correlation was a function for single-phase flow multiplied by a function incorporating parameters for two-phase flow. Over 1200 data points were used to produce the correlation.