scholarly journals Modeling of Pressure Drop During Refrigerant Condensation in Pipe Minichannels

2017 ◽  
Vol 38 (4) ◽  
pp. 15-28 ◽  
Author(s):  
Małgorzata Sikora ◽  
Tadeusz Bohdal
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Computer Modeling ◽  
Experimental Verification ◽  
Flow Resistance ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Flow Conditions ◽  
Conservation Equations ◽  
Mathematical And Computer Modeling

Abstract Investigations of refrigerant condensation in pipe minichannels are very challenging and complicated issue. Due to the multitude of influences very important is mathematical and computer modeling. Its allows for performing calculations for many different refrigerants under different flow conditions. A large number of experimental results published in the literature allows for experimental verification of correctness of the models. In this work is presented a mathematical model for calculation of flow resistance during condensation of refrigerants in the pipe minichannel. The model was developed in environment based on conservation equations. The results of calculations were verified by authors own experimental investigations results.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

scholarly journals Experimental Investigations of Cold Flow Mass Distribution and Pressure Drop Characteristics in a Structured Honeycomb Monolith Bed

2015 ◽  
Vol 9 (1) ◽  
pp. 302-311 ◽  
Author(s):  
Mingming Mao ◽  
Yongqi Liu ◽  
Ruixiang Liu ◽  
Bin Zheng ◽  
Jian Meng
Keyword(s):  
Pressure Drop ◽  
Mass Distribution ◽  
Total Pressure ◽  
Flow Resistance ◽  
Flow Reversal ◽  
Experimental Investigations ◽  
Test Rig ◽  
Cold Flow ◽  
Reactor Test ◽  
Distribution Uniformity

The thermal flow reversal reactor (TFRR) and catalytic flow reversal reactor (CFRR) can utilize the ventilation air methane (VAM) from coal mines effectively. The initial cold feed flow mass distribution uniformity in the monolith oxidation bed, the critical part of both reactors, has a great influence on the stability of methane oxidation process and conversation rate. So the emphases are put on the experimental investigations of the cold flow mechanics in the monolith bed based on a simplified reactor test rig. Firstly, the flow resistance coefficients of the monolith bed were calculated, and then the flow resistance mathematical model was built. It was found that the flow mass distribution uniformity was affected by the pressure drop distribution in the monolith bed, and obviously decreased with increasing inlet velocity. The pressure drop distribution was analyzed through a modified momentum equation. The total pressure loss in the lower header was evidently higher than that in the upper header or monolith bed. Additionally, the local losses at the inlet and outlet of the monolith bed were small, so they could be ignored. Finally, the formula of total pressure losses under different flow conditions was established based on the simplified reactor test rig.

Delta Winglet Pairs in the Core of a Pipe and its Effect on Heat Transfer and Flow

2019 ◽  
Author(s):  
Md. Islam ◽  
Z. Chong ◽  
Md. Alam
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Flow Behavior ◽  
Experimental Results ◽  
Vortex Generators ◽  
Experimental Investigations ◽  
Longitudinal Vortices ◽  
The Core ◽  
Delta Winglet

Abstract Vortex generators/turbulent promoters generate the longitudinal vortices which introduce the better mixing of the fluid with fluid circulation and enhance heat transfer. In this research, experimental investigations have been carried out to study the effect of delta winglet vortex generator (DWVG) in the core of the pipe on heat transfer and flow behavior. In this experiment, two pairs of delta winglet vortex generators (DWVG) were printed on the upside and downside of the thin plate using 3D printing technology in a ring and then placed in the core of the pipe to generate longitudinal vortices. Middle plate was very thin. The effect of heights (H = 5mm, 10mm, 15mm and 20mm) of DWVG for 10° angle of attack and 15mm spacing between leading edges of VG pairs on heat transfer and pressure drop was studied. The experiments were conducted for a fully developed turbulent flow of air in the range of Reynolds numbers (Re) 5000–25000. The influence of the DWVGs on heat transfer and pressure drop was investigated in terms of the Nusselt number (Nu) and friction factor (f). The experimental results indicate that DWVG in the core of the tube results in a considerable increase in Nu with some pressure penalty. It is found that DWVG increase Nu considerably only when H is over 10mm. Nu increases with Re and H. Friction factor decreases with Re but increase with H. The thermal performance enhancement (TPE) was noticed decreasing with Re. TPE could be obtain up to 1 only when the height is over 10mm for Re ≤ 7500. The experimental results show that the DWVG in the core of the pipe is not a good option to enhance the heat transfer at a higher Re.

Pneumotransport of Grains Through a Pipeline

2002 ◽  
Author(s):  
Kaushal K. Shrivastava
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Horizontal Pipe ◽  
Pressure Drops ◽  
Central Topic ◽  
The Mathematical Model ◽  
Mustard Seeds

Determination of pressure drop correlation using experimental techniques has been a central topic of research in the area of pneumotransport. However, the objective of the present investigation is to apply the mathematical model (SK model) developed by the author [1,2] along with other correlations [3–5] to estimate pressure drops for conveying varieties of grains through horizontal pipe and compare the values with the experimental results of Siegel [6]. The SK model has also been utilized to calculate pressure drops for conveying mustard seeds pneumatically through horizontal, inclined and vertical pipes and compare the values with the experimental results of Rose and Barnacle [7]. It is evident from various comparisons shown in this paper that the SK model predicts the values of pressure drop accurately as compared to the experimental results in all the cases of grains transport through horizontal, inclined, and vertical pipes, whereas, other correlations do not predict accurate results consistently in all cases.

Airside Pressure Drop Mechanism of Automobile Air-Conditioner Evaporator Plating with Hydrophilic Film

2012 ◽  
Vol 178-181 ◽  
pp. 2850-2853
Author(s):  
Qin Ouyang
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Relative Humidity ◽  
Experimental Results ◽  
Air Conditioner ◽  
Proposed Model ◽  
Air Resistance ◽  
Automobile Air Conditioner ◽  
Wet Condition ◽  
Hydrophilic Treatment

A mathematical model of airside pressure drop was established, and calculations were conducted respectively under dry condition and wet condition for evaporators with hydrophilic treatment and without hydrophilic treatment. Experimental results demonstrate the proposed model. The results reveal a significant improvement of hydrophilic treatment, and air resistance drops to 53% when relative humidity is 50%, while it drops to 50% when relative humidity is 90%.

scholarly journals Mathematical model reveals that heterogeneity in the number of ion transporters regulates the fraction of mouse sperm capacitation

2021 ◽  
Author(s):  
Alejandro Aguado-García ◽  
Daniel A. Priego-Espinosa ◽  
Andrés Aldana ◽  
Alberto Darszon ◽  
Gustavo Martínez-Mekler
Keyword(s):  
Mathematical Model ◽  
Experimental Verification ◽  
Intracellular Signaling ◽  
Female Genital Tract ◽  
Experimental Studies ◽  
Fertility Control ◽  
Experimental Results ◽  
Loss Of Function ◽  
Ion Transporters ◽  
Individual Number

AbstractCapacitation is a complex maturation process that mammalian sperm must undergo in the female genital tract to be able to fertilize an egg. This process involves, amongst others, physiological changes in flagellar beating pattern, membrane potential, intracellular ion concentrations and protein phosphorylation. Typically, in a capacitation medium, only a fraction of sperm achieve this state. The cause for this heterogeneous response is still not well understood and remains an open question. Here, one of our principal results is to develop a discrete regulatory network, with mostly deterministic dynamics in conjunction with some stochastic elements, for the main biochemical and biophysical processes involved in the early events of capacitation. The model criterion for capacitation requires the convergence of specific levels of a select set of nodes. Besides reproducing several experimental results and providing some insight on the network interrelations, the main contribution of the model is the suggestion that the degree of variability in the total amount and individual number of ion transporters among spermatozoa regulates the fraction of capacitated spermatozoa. This conclusion is consistent with recently reported experimental results. Based on this mathematical analysis, experimental clues are proposed for the control of capacitation levels. Furthermore, synergistic and interference traits that become apparent in the modelling among some components also call for future theoretical and experimental studies.Author SummaryFertilization is one of the fundamental processes for the preservation of life. In mammals sperms undergo a complex process during their passage through the female tract known as capacitation which enables them for fertilization. At the present time it is accepted from experimental observation, though not understood, is that only a fraction of the sperm is capacitated. In this work, by means of a network mathematical model for regulatory spermatozoa intracellular signaling processes involved in mice capacitation, we find that the variability in the distribution of the number of ion transporters intervenes in the regulation of the capacitation fraction. Experimental verification of this suggestion could open a line of research geared to the regulation of the degree of heterogeneity in the number of ion transporters as a fertility control. The model also uncovers through in silico hyperactivation, loss of function and knockout of network elements, synergetic traits which again call for experimental verification.

scholarly journals Flow resistance in the engine inlet-exhaust system as affected by the engine parameters

2009 ◽  
Vol 136 (1) ◽  
pp. 31-40
Author(s):  
Zbigniew ŻMUDKA ◽  
Stefan POSTRZEDNIK
Keyword(s):  
Pressure Drop ◽  
Flow Resistance ◽  
Exhaust System ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Test Results ◽  
Flow Conditions ◽  
Inlet System ◽  
Engine Operation ◽  
Fresh Charge

The paper presents theoretical and experimanetal research into the process of charge exchange in a spark ignition engine (the process of cylinder filling and discharging). A significant role in the inlet system plays the resistance of the flow of a fresh charge through the throttle, particularly when its partially opened. In classic spark ignition engine solutions this flow resistance is a part of the engine load imposition. The problem has been illustrated by the theoretical and experimental test results of the influence of the pressure drop Δpd on the side of the fresh charge flow and the pressure drop Δpw in the exhaust system on the engine operation. Relations have been determined between the engine operating parameters and the flow conditions of the charge/exhaust gases.

Investigation and Computer Simulation of Diesel Injection System With Rotative Pump

1990 ◽  
Vol 112 (3) ◽  
pp. 317-323 ◽  
Author(s):  
A. Ficarella ◽  
D. Laforgia ◽  
G. Cipolla
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Conservation Laws ◽  
Momentum Conservation ◽  
Experimental Results ◽  
Injection System ◽  
Experimental Investigations ◽  
System Behavior ◽  
Diesel Injection ◽  
Theoretical Predictions

The behavior of an injection system with a rotative pump for reciprocating engines has been investigated. Experimental investigations were carried out using a specially designed apparatus to monitor several parameters, such as pressure inside the different chambers of the apparatus, moving part lift, and injected fuel quantity. In addition, a predictive mathematical model, based on mass momentum conservation laws, was developed to simulate such behavior and to predict all the most important parameters of the injection system. The comparison between numerical and experimental results has been satisfactory, allowing a generalization of the model and extensive theoretical predictions of the system behavior.

scholarly journals Computer Modeling of Aerosol Emissions Spread in the Atmosphere

2019 ◽  
Vol 97 ◽  
pp. 05023 ◽  
Author(s):  
Daler Sharipov ◽  
Sharofiddin Aynakulov ◽  
Otabek Khafizov
Keyword(s):  
Boundary Layer ◽  
Mathematical Model ◽  
Atmospheric Boundary Layer ◽  
Computer Modeling ◽  
Numerical Experiments ◽  
Climatic Factors ◽  
Numerical Algorithms ◽  
Aerosol Emissions ◽  
The Given ◽  
And Diffusion

The paper deals with the development of mathematical model and numerical algorithms for solving the problem of transfer and diffusion of aerosol emissions in the atmospheric boundary layer. The model takes into account several significant parameters such as terrain relief, characteristics of underlying surface and weather-climatic factors. A series of numerical experiments were conducted based on the given model. The obtained results presented here show how these factors affect aerosol emissions spread in the atmosphere.

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