Experimental Investigation on the Condensation Efficiency of Humid Air in a Cross-Flow Condenser

2013 ◽  
Author(s):  
Hojin Ahn ◽  
Burhan Gul ◽  
Yavuz Sahin ◽  
Onur Hartoka
Keyword(s):  
Flow Rate ◽  
Single Channel ◽  
Cross Flow ◽  
Condensation Process ◽  
Mixture Flow ◽  
Flow Rates ◽  
Cooling Flow ◽  
Cooling Air Flow ◽  
Cooling Air ◽  
Heat Released

The condensation of steam in the presence of air has been investigated experimentally in the cross-flow flat-plate single-channel condenser. In particular, the condensation efficiency which is defined by the ratio of heat released during the condensation process (the amount of latent heat) to the total heat extracted from the mixture of vapor and non-condensable gas (the sum of latent and sensible heats) is examined as a function of the air-steam mixture temperature and humidity at inlet and the flow rates of the air-steam mixture and cooling air. The preliminary results are obtained with the operating condition of the air-steam mixture flow at 70°C and 80, 85 and 90% relative humidity at inlet. The most notable result is that the condensation efficiency evidently decreases with the increase of the cooling air flow rate. With both mixture and cooling flow rates kept constant, the condensation efficiency increases, as expected, with the increasing air-steam mixture humidity at the inlet. On the other hand, the air-steam mixture flow rate appears to have little effect on the condensation efficiency.

The Prediction of Flow Through Leading Edge Holes in a Film Cooled Airfoil With and Without Inserts

1985 ◽  
Vol 107 (1) ◽  
pp. 92-98 ◽  
Author(s):  
E. S. Tillman ◽  
E. O. Hartel ◽  
H. F. Jen
Keyword(s):  
Leading Edge ◽  
Flow Rates ◽  
Cooling Flow ◽  
Internal Loss ◽  
Measured Flow ◽  
Flow Through ◽  
Loss Coefficients ◽  
Cooling Air Flow ◽  
Cooling Air ◽  
Good Agreement

A method for predicting cooling air flow rates using tests on cylindrical models of typical turbine blade leading edges has been extended to include blades with inserts and blades with reversed-angled holes. When an insert is used, the pressure loss across the insert can be determined from flow tests and added to other losses in the flow path to determine cooling flow rates. Calculated and experimentally determined flow rates are compared with good agreement. The second experiment was performed to determine internal loss coefficients for reverse-angled holes oriented so the flow makes a reverse turn to enter the holes. The reversed flow case produced significantly greater internal loss coefficients than when the same holes were oriented in the direction of flow. These results were used to predict flow from arrays of reverse- angled holes and from a cylinder containing both reverse-angled holes and nonreversed holes. In all cases, good agreement was found between predicted and measured flow rates.

scholarly journals Four Layer Cylindrical Model of Mucus Transport in the Lung: Effect of Prolonged Cough

2019 ◽  
Vol 19 (1) ◽  
pp. 53-63
Author(s):  
Arti Saxena ◽  
Vijay Kumar ◽  
JB Shukla
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Circular Tube ◽  
Medical Science ◽  
Moist Air ◽  
Serous Fluid ◽  
Mixture Flow ◽  
Flow Rates ◽  
Immotile Cilia ◽  
Laminar Condition

Background: In this paper, a four layer model of the simultaneous and coaxial flow of moist air, mucus, mixture of mucin and periciliary liquid and serous fluid (assumed to be incompressible and Newtonian fluids) in a circular tube under time dependent pressure gradient representing prolonged cough is analyzed to study the mucus transport in an airway in the presence of prolonged cough. It is assumed that air and mucus flow under quasi steady state turbulent conditions while the mixture of mucin and periciliary liquid and serous layer surrounding mixture layer flows under unsteady laminar condition in presence of immotile cilia carpet. Result: It is shown that the mucus transport increases as the viscosity of serous fluid decreases. Also the mixture and serous fluid flow rates increase as the viscosity of serous fluid decreases. It is also observed that the effect of resistance to flow by serous fluid in the cilia bed is to decrease flow rates. The flow rates of mucus and mixture of mucin and periciliary fluid increase as the viscosity of mixture decreases also air and mixture of mucus and periciliary fluid flow rates increase as the thickness of mixture increases. Conclusion: As the thickness of mucus increases its flow rate increases on the other hand the mixture flow rate, mucus and serous fluid flow rate decreases with the increase of the mixture thickness. Bangladesh Journal of Medical Science Vol.19(1) 2020 p.53-63

Experimental Feasibility Study of Radial Injection Cooling of Three-Pad Air Foil Bearings

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Suman K. Shrestha ◽  
Daejong Kim ◽  
Young Cheol Kim
Keyword(s):  
Heat Exchange ◽  
Flow Rate ◽  
High Speed ◽  
Air Flow ◽  
Air Flow Rate ◽  
Design Factor ◽  
Cooling Performance ◽  
Radial Injection ◽  
Cooling Air Flow ◽  
Cooling Air

The foil bearing (FB) is one type of hydrodynamic bearing using air or another gas as a lubricant. When FBs are designed, installed, and operated properly, they are a very cost-effective and reliable solution for oil-free turbomachinery. Because there is no mechanical contact between the rotor and its bearings, quiet operation with very low friction is possible once the rotor lifts off the bearings. However, because of the high speed of operation, thermal management is a very important design factor to consider. The most widely accepted cooling method for FBs is axial flow cooling, which uses cooling air or gas passing through heat-exchange channels formed underneath the top foil. The advantage of axial cooling is that no hardware modification is necessary to implement it, because the elastic foundation structures of the FB serve as the heat-exchange channels. Its disadvantage is that an axial temperature gradient exists on the journal shaft and bearing. In this paper, the cooling characteristics of axial cooling are compared with those of multipoint radial injection, which uses high-speed injection of cooling air onto the shaft at multiple locations. Experiments were performed on a three-pad FB 49 mm in diameter and 37.5 mm in length, at speeds of 30,000 rpm and 40,000 rpm. Injection speeds were chosen to be higher than the journal surface speed, but the total cooling air flow rate was matched to that of the axial cooling cases. Experimental results show that radial injection cooling is comparable to axial cooling at 30,000 rpm, in terms of cooling performance. Tests at 40,000 rpm reveal that the axial cooling performance reaches saturation when the pressure drop across the bearing is larger than 1000 Pa, while the cooling performance of radial injection is proportional to the cooling air flow rate and does not become saturated. Overall, multipoint radial injection is better than axial cooling at high rotor speeds.

Analysis of Influencing Factors of Pressure Pre-Cooling Rate for Fruits and Vegetables

2013 ◽  
Vol 732-733 ◽  
pp. 581-584
Author(s):  
Qiang Wang ◽  
Fan Wang ◽  
Qi Wang ◽  
Feng Zhen Liu
Keyword(s):  
Cooling Rate ◽  
Fruits And Vegetables ◽  
Air Flow ◽  
Evaluation Index ◽  
Air Flow Rate ◽  
Cooling Process ◽  
Flow Rates ◽  
Different Shapes ◽  
Cooling Air Flow ◽  
Cooling Air

Cooling rate is an important evaluation index of pressure pre-cooling effect for fruits and vegetables. Experimental device of pressure pre-cooling for fruits and vegetables has been established. Pre-cooling process of golden pears has been tested. The key parameters which affected pressure pre-cooling 7/8 cooling time of golden pears such as different air flow rates, different shapes and sizes of vent hole and arrange form have been analyzed. The results show that it is better that cooling air flow rate is between 1.5 m/s and 2 m/s. Ellipse vent hole shape is the best vent hole style and key-groove vent hole is the worst. The cooling rate of stagger array form is faster than the parallel array form.

Three-dimensional multiphase flow modeling of membrane humidifier for PEM fuel cell application

2019 ◽  
Vol 30 (1) ◽  
pp. 54-74
Author(s):  
Seyed Ali Atyabi ◽  
Ebrahim Afshari ◽  
Mohammad Yaghoub Abdollahzadeh Jamalabadi
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Three Dimensional ◽  
Cross Flow ◽  
High Volume ◽  
Volume Flow ◽  
Dew Point ◽  
Multiphase Model ◽  
Flow Rates ◽  
Content Type

Purpose In this paper, a single module of cross-flow membrane humidifier is evaluated as a three-dimensional multiphase model. The purpose of this paper is to analyze the effect of volume flow rate, dry temperature, dew point wet temperature and porosity of gas diffusion layer on the humidifier performance. Design/methodology/approach In this study, one set of coupled equations are continuity, momentum, species and energy conservation is considered. The numerical code is benchmarked by the comparison of numerical results with experimental data of Hwang et al. Findings The results reveal that the transfer rate of water vapor and dew point approach temperature (DPAT) increase by increasing the volume flow rate. Also, it is found that the water recovery ratio (WRR) and relative humidity (RH) decrease with increasing volume flow rate. In addition, all mixed results decrease with increasing dry side temperature especially at high volume flow rates and this trend in high volume flow rates is more sensible. Although the transfer rate of water vapor and DPAT increases with increasing the wet inlet temperature, WRR and RH reduce. Increasing dew point temperature effect is more sensible at the wet side is compared with the dry side. The humidification performance will be enhanced with increasing diffusion layer porosity by increasing the wet inlet dew point temperature, but has no meaningful effect on other operating parameters. The pressure drop along humidifier gas channels increases with rising flow rate, consequently, the required power of membrane humidifier will enhance. Originality/value According to previous studies, the three-dimensional numerical multiphase model of cross-flow membrane humidifier has not been developed.

Process of AC multichannel gliding arcs discharge in rotational flow

2020 ◽  
pp. 2150029
Author(s):  
Wei-Zhen Wang ◽  
Min Jia ◽  
Fei-Long Song ◽  
Zhi-Bo Zhang ◽  
Wei Cui
Keyword(s):  
Flow Rate ◽  
Single Channel ◽  
Diagnostic Methods ◽  
Plasma Actuators ◽  
Maximum Height ◽  
Rotational Flow ◽  
Flow Rates ◽  
Response Characteristics ◽  
Plasma Distribution

In order to solve the problem of small and asymmetrical plasma area of the gliding arc (GA) in the chemical treatment process, a plasma actuator driven by alternating current (AC) with a frequency of 23.2kHz was designed to multichannel gliding arcs (MGAs) in a rotational air flow at atmospheric pressure. The spatiotemporally resolved discharge characteristics of the MGA, including long-length breakdown, long-term extinction and typical breakdown features, were investigated combining optical and electrical diagnostic methods simultaneously at a flow rate of 250 SLM (standard liter per minute). The response characteristics of MGA under different flow rates were analyzed. On average, the MGA exhibit 48.8% more discharge power compared to traditional single-channel GA under flow rates of 50–250 SLM, which is due to the GAs continual existence at long-length state, representing better stability of the MGA plasma actuators. It was observed that the frequency of typical breakdown and long-term extinction increased as the flow rate accelerated, and the maximum height the GA could reach decreased with the number of channels increasing from 1 to 5, which can be attributed to the power decline of separate channels of GAs at 50 SLM. It was also found that MGA showed a broader plasma distribution of low electron temperature than traditional single-channel GA.

Two-Phase Flow Visualization for a Hybrid Heat Sink

2018 ◽  
Author(s):  
Danish Rahman ◽  
Ahmad Almomani ◽  
Ibrahim Hassan ◽  
Yasser Al-Hamidi ◽  
Aziz Rahman
Keyword(s):  
Flow Rate ◽  
Slug Flow ◽  
Air Flow ◽  
Plug Flow ◽  
Cross Flow ◽  
Flow Regimes ◽  
Air Flow Rate ◽  
Two Phase ◽  
Flow Rates ◽  
Impingement Jet

This paper aimed to study two-phase flow under adiabatic conditions through the process of flow visualization. This was done through the use of a test section with a cross flow and a jet impingement (swirl jet). The flow regimes under different air-water flow rates were determined using a high-speed camera that recorded digital videos. For each of the flow rates the pressure differential between the inlet and the outlets were measured. Through the pressure drop it is proposed that the types of flow regimes may later be able to be predicted. Nine air-water flow rates were considered to collect data and generate a flow map for the impingement jet and cross flow. The major observed flow regimes within the crossflow and impingement jet followed the predicted trend with bubbly and plug flow in the former, and slug flow in the latter. It was further observed that increasing the air flow rate increased the likelihood of bubbly and plug flow in both the cross-flow and impingement jet. In the cross flow, a lower air flow rate resulted in bubbly flow while within the impingement jet, a lower air flow rate resulted in slug flow.

Cooling Air Flow Characteristics in Gas Turbine Components

1982 ◽  
Vol 104 (2) ◽  
pp. 275-280 ◽  
Author(s):  
H. F. Jen ◽  
J. B. Sobanik
Keyword(s):  
Gas Turbine ◽  
Analytical Model ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Air Flow ◽  
Flow Characteristics ◽  
Calibration Procedure ◽  
Bench Test ◽  
Cooling Air Flow ◽  
Cooling Air

An analytical model for the prediction of cooling air flow characteristics (mass flow rate and internal pressure distribution) in gas turbine components is discussed. The model addresses a number of basic flow elements typical to gas turbine components such as orifices, frictional passages, labyrinth seals, etc. Static bench test measurements of the flow characteristics were in good agreement with the analysis. For the turbine blade, the concept of equivalent pressure ratio is introduced and shown to be useful for predicting (i) the cooling air flow rate through the rotor blade at engine conditions from the static rig and (ii) cooling air leakage rate at the rotor serration at engine conditions. This method shows excellent agreement with a detailed analytical model at various rotor speeds. A flow calibration procedure preserving flow similarity for blades and rotor assemblies is recommended.

The Influence of Channel Orientation and Flow Rates on the Bubble Formation in a Liquid Cross-Flow

2010 ◽  
Author(s):  
Kamran Siddiqui ◽  
Wajid A. Chishty
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Gas Turbines ◽  
Alternative Fuels ◽  
Bubble Formation ◽  
Cross Flow ◽  
Operating Conditions ◽  
Flow Rates ◽  
Bubble Detachment ◽  
Wide Range

For gas turbines burning liquid fuels, improving fuel spray and combustion characteristics are of paramount importance to reduce emission of pollutants, improve combustor efficiency and adapt to a range of alternative fuels. Effervescent atomization technique, which involves the bubbling of an atomizing gas through aerator holes into the liquid fuel stream, has the potential to give the required spray quality for gas turbine combustion. Bubbling of the liquid stream is presently used in a wide range of other applications as well such as spray drying, waste-water treatment, chemical plants, food processing and bio- and nuclear-reactors. In order to optimize control of the required aeration quality and thus the resulting spray quality over a wide range of operating conditions, it is important that the dynamics of bubble formation, detachment and downstream transport are well understood under these circumstances. The paper reports on an experimental study conducted to investigate the dynamics of gas bubbles in terms of bubble detachment frequency when injected from an orifice that is subjected to a liquid cross-flow. The experiments were conducted over a range of gas and liquid flow rates and at various orientations of the liquid channel. Analyses presented here are based on shadowgraph images of two-phase flow, acquired using a high speed camera and a low intensity light source. An image processing algorithm was developed for the detection and characterization of the bubble dynamics. Results show that bubble detachment frequency is a function of both liquid cross-flow rate and the gas-to-liquid flow rate ratio.

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