Discharge Duct Research Articles

An Experimental Study for Air Temperature Distribution in a Conditioned Room Using Various Vertical Locations of Conditioned Air Ducts

The Air distribution phenomenon is most useful in thermal environment study and its effectiveness. The main aim of this investigation is to examine and discover the thermal properties of the inside area and its thermal environment. The experimental work for research was studied at the first-floor lab of the government women’s polytechnic, Bhopal. The experiment was conducted in the summer and winter seasons in a closed-conditioned room with the arrangement of a conditioned air discharge duct. The conditioned air was discharged through the circular pipe duct which was set vertically. The duct has arrangements to discharge the air through various vertical positions as the lower duct (L), middle duct (M), and upper duct (U). This experimental work investigates supply air velocity and vertical temperature variation effectiveness inside said test room. The experiment results were collected with lower, middle, and vertical duct opening conditions respectively. The vertical temperature variation and air velocity at the outlet of the duct were noted with considerable points at 1 m from each inside the test room space. The outcome of the results shows the indoor thermal environment and vertical temperature distribution were affected by the discharge air duct position and supply air velocity. The temperature profile vertically impacted when the measuring test point position was near the discharge air duct and it became quite consistent in respective measurements from a large distance.

Clinical Significance of Contrast-Enhanced Ultrasound Galactography in Pre-operative Diagnosis of Patients With Pathologic Nipple Discharge

ObjectiveThe aim of the work described here was to investigate the feasibility and diagnostic value of using contrast-enhanced ultrasound (CEUS) galactography with SonoVue in patients with pathologic nipple discharge (PND). MethodsTwenty-eight patients who underwent breast surgery for PND from May 2019 to August 2021 were included. Routine ultrasound, ductoscopy and CEUS galactography were performed successively. Lesions were diagnosed and localized. The sensitivity, specificity and pre-operative localization value of each examination method were evaluated on post-operative pathology. ResultsCEUS galactography was successfully conducted in all 28 patients and revealed negative ductal ectasia, filling stop and filling defect. Ductoscopy revealed positive nodules in 21 cases and negative nodules in 7 cases. A total of 18 nodules were found by routine ultrasound, and the relationship between all nodules and the discharge duct was confirmed after CEUS galactography. Compared with the other two methods, CEUS galactography had higher sensitivity, positive predictive value and negative predictive value (100%, 81.82% and 100%, respectively), while it has the same specificity as routine ultrasound (both 60%). The pre-operative location of the nipple duct was consistent with the intra-operative findings in 28 patients after CEUS galactography. ConclusionThe ultrasound contrast agent SonoVue can be used for CEUS galactography in patients with PND. CEUS galactography can improve the detection of ductal nodules and locate the nipple discharge duct pre-operatively. As the technique does not emit radiation and SonoVue is easily metabolized and safe, CEUS galactography is better than conventional imaging for PND patients.

Study of the effect of virtual mass force on two-phase critical flow

Abstract Critical (choked) flow is a highly concerning phenomenon in safety analysis for nuclear energy. The discharge mass flow rate prediction is crucial for engineering design and emergency response in case of nuclear accidents. Unfortunately, the critical flow is difficult to predict especially when the two-phase flow exists. The accuracy is based on a deeper understanding of the complex phenomenon of critical flow. The influence of virtual mass force on the two-phase critical flow was seldom concentrated on owing to the lack of suitable critical flow models for studies in detail. This study is based on a developed 6-equation two-phase critical flow model. It is confirmed that the virtual mass force contributes to the stability and convergence of the critical flow simulation and it will impact not only the critical mass flux but also the thermal hydraulic parameters along the discharge duct. The magnitude depends on the geometry of the discharge duct and the upstream condition. It is larger when the duct is longer and the pressure is lower. Furthermore, the virtual mass force for each flow regime was studied in detail with a sensitivity study. The results show that the most sensible condition for the virtual mass force is annular flow along a long tube under relatively low pressure. The future work is to develop a correlation of virtual mass force for critical flow specifically since the correlations in the literature were developed under general two-phase flow process conditions.

Development of flow-vibroacoustic coupled numerical methods for prediction of noise radiation due to flow-born vibration of compressor discharge piping system

The compressor and fan in air conditioner outdoor unit are the core component which deter-mines noise performance as well as cooling or heating performance. Among these, the com-pressor has larger contribution to the noise of outdoor units. For high efficiency air condition-er, the size and operating speed of compressor are smaller and faster. The high-speed com-pressor causes loud noise which is complaints for the customer. Traditionally, it is well-known that the vibration of compressor and connected duct is main noise source. However, as the compressor speed increases, the refrigerant flow in the compressor discharge duct also emerged as a major noise source. To reduce the compressor noise operating at high speed, it is necessary to analyze vibrational and acoustic characteristics of compressor discharge duct. This duct noise has the two-types source: structure born noise and flow induced noise. The structure born noise is generated by the duct vibration caused by compressor movement. For the flow induced noise, the static pressure field of refrigerant flow in the duct is vibrational source. In this paper, the compressor discharge duct noise considering two mechanisms was investigated. The refrigerant flow is solved using CFD and duct vibration and noise radiation are computed by FE-BE method.

A way to increase the efficiency of straw spreaders

The use of high-quality bedding is important for the health of farm animals. Straw is an excellent material for bedding, but before use it must be crushed to particles no larger than 100 mm, which will achieve optimal moisture and gas absorption capacity, as well as simplify the mechanization of application and cleaning. Centrifugal spreaders, belt conveyors and blow spreaders are used to apply litter. The paper considers some types of litter spreaders used in farms in the north-West. It is revealed that, along with the obvious advantages, the considered machines have disadvantages. The main one is the uneven distribution of the litter when it is applied. This, in turn, leads to the need for manual labor when leveling the straw layer after its introduction in a mechanized way. A new design of the spreader-blower is proposed aimed at ensuring the uniformity of the litter layer during application. The calculation of optimization of some parameters of the new installation is described. In addition to the calculated value of the straw particle velocity, the angle of inclination of the front wall of the discharge duct is also determined.

Meibography in meibomian gland dysfunction with digital biomicroscopy

Dry eye disease (DED) is one of the most common conditions encountered by ophthalmologists in their practice. Currently, experts consider meibomian gland dysfunction to be the leading cause of dry eye syndrome. This condition is characterized by obstruction of meibomian gland discharge ducts and/or changes in their glandular secretion, which leads to disturbance of tear film stability and provokes inflammatory process of ocular surface.The purpose of this publication is to acquaint ophthalmologists and optometrists with the procedure of meibography, a diagnostic method that allows a qualitative and quantitative assessment of the meibomian glands and to determine the degree of their dysfunction.The first part of the workshop presents the anatomical aspects of the normal structure of the meibomian glands and their dysfunction. The second part describes the technique for diagnosing meibomian gland dysfunction. The third part presents the meibography algorithm and its interpretation.

CFD Simulation of Thermal Plume of VRF Air Conditioners for Cooling Season in Semi-Closed Spaces for Erbil Climate Conditions

The variable refrigerant flow (VRF) system is extensively utilized for the purpose of space cooling and heating in residential and commercial buildings. The VRF outdoor units are frequently placed on balconies of multi-storey buildings, and the aluminum louvers conceal them to keep the aesthetic architecture appearance. This type of installation will cause the thermal plume influence of the dissipated heat discharged from condensing units to cause high suction temperature, high energy consumption, and low coefficient of performance of the system. The numerical results showed that the discharged heat from condensing units will lead to rising thermal plume influence, causing greater suction temperatures for VRF outdoor units on top floors, even overriding the operating temperature range. It also shows that removing the inward louver in front of the discharge duct on each floor is an efficient method to deteriorate the thermal plume influence for VRF air conditioners and enhance the thermal efficiency of the entire system. For the proposed design, the average suction temperatures could be reduced by 8%, 15%, and 19% for VRF outdoor units for floors 10th, 11th, & 12th, respectively. This work aims to provide guidelines for the placement of VRF air conditioners in buildings in the designing stage.

Examination of the Airflow Uneven Distribution over the Combine Harvester Cleaning System

The research aims to study the uneven distribution of airflow created by a fan over the cleaning system of a combine harvester, affecting the efficiency of the technological process of separating impurities from the original crop. The article presents a methodology for studying the actual operation process using a digital twin, reveals problem areas and studies even distribution of the airflow at the outlet of the fan discharge channel of the combine harvester cleaning system. During the research, several parameters were defined. Based on the digital twin development and study, the airflow rate at the outlet of the radial fan discharge duct of the combine harvester (CH) cleaning system at different rotation rates of the fan wheel (450-1050 min-1) was determined. Experimental measurements of the airflow distribution over the working part of the sieve shoe for the existing cleaning system and modern combine harvesters made up 3.75-10.2 m/s.

Design, construction and testing of a floating hood biodigester prototype for municipal waste organic waste

This paper documented the design, construction and operation test of a floating hood biodigester prototype, using organic residues (ruminal content, blood, bovine excreta and viscera) from the municipal trail of Ciudad Valles, S.L.P., with the purpose of generating biogas. The components of the biodigester system considered were: loading duct, concrete biodigester tank, biogas pipeline, floating hood, gas reservoir, discharge duct and discharge tank. A biodigester with storage capacity in the 0.178 m3 floating hood was designed for a 30-day trial operation and storage of 0.120 m3 of organic waste mixture in the biodigester tank. As of day 17 of operation the daily average of biogas generated was 0.1801 m3. The composition of the biogas at day 30 of operation, showed a content of 59.4% of CH4. When performing the flame test, an intense blue coloration was obtained, which indicates that the biogas produced has a high calorific value that will allow heating and flammability.

CFD Modeling of Flame Jump across Air Gap between Evasé and Capture Duct for Ventilation Air Methane Abatement

The ventilation air–methane (VAM) released from underground mines is often transported into regenerative thermal oxidizer (RTO) devices and burnt into heat energy. This study numerically investigates the scenarios where explosion occurs inside the RTO and the flame and pressure waves propagate back quickly towards the VAM discharge duct. Possibilities of secondary explosion in the discharge duct, hence in the downstream underground mines, are examined. The results critically showed that when the methane concentration accumulated in the RTO reached 7.5% or above, the flame generated from the explosion jumped to the evasé of the discharge section (over a distance of 29.4 m) and could induce explosions in underground mines.

Effect of sodium bicarbonate powder on the process of ducted venting

To investigate the effect of sodium bicarbonate on the process of ducted venting, an experimental study was performed to suppress the methane-air explosions in a 5 L vessel connected with different duct length (250 mm、500 mm、750 mm) under NaHCO3 dry powder with the mass fraction C=0 g/m3, 40 g/m3, 80 g/m3, 120 g/m3, 160 g/m3, 200 g/m3, 240 g/m3. The flame front propagation and explosion overpressure waveform were analyzed. The results show that NaHCO3 powder greatly weakened the secondary explosion in the discharge duct, and the appropriate mass fraction of NaHCO3 powder eliminated the secondary explosion. As the NaHCO3 powder mass fraction increased, the flame structure in the vessel was gradually irregular, and the flame in the discharge duct went through the process of weakening to extinguishing. Moreover, the time for the flame to reach the end of the vessel was prolonged with the increase of powder mass fraction. Different mass fraction of NaHCO3 dry powder led to three development modes of flame velocity. The mechanism for the pressure rise in the vessel depended on the NaHCO3 powder mass fraction. The maximum pressure in the vessel (pv, max) was mainly dominated by the second pressure peak (p2) for the low powder mass fraction, but by the first pressure peak (p1) for the high powder mass fraction. The drop rate of overpressure increased at first and then leveled off with the increase of NaHCO3 powder mass fraction, which indicating that the mass fraction effect gradually weaken. Finally, the relationship between flame propagation velocity and explosion overpressure in the ducted vented vessel was quantitatively analyzed.

Study on the combined effect of duct scale and SBC concentration on duct-vented methane-air explosion

A gas explosion is often vented to a safe location by means of a discharge duct. However, the presence of a discharge duct increases the explosion severity in the vessel, inducing a higher explosion overpressure compared to a simply vented vessel. To reduce the explosion overpressure in the vessel, an experimental study was performed to suppress the methane-air explosions in a 5 L vessel connected to a discharge duct of different scales (e.g., length and diameter) and with various sodium bicarbonate concentrations. The results show that the initial flame propagation process in the vessel was basically similar in the simply vented vessel and in the vessel vented through a discharge duct (i.e., ducted-vessel). In the middle and late stages of flame propagation in the vessel, the flame fragmentation was more pronounced for the ducted-vessel. Moreover, the degree of flame fragmentation in the vessel increased with the duct length. The flame structure in the vessel was more irregular for a larger vent coefficient (Kv = 9.75). The more pronounced quenching in the short duct (250 mm duct) is related to the high inhibition efficiency due to the leakage of a large amount of sodium bicarbonate (SBC) powder into the discharge duct while in the long duct (750 mm duct) the disturbance is due to the strong turbulence. The appropriate SBC concentration can transform the mechanism for the pressure rise in the vessel. At high powder concentrations the maximum pressure in the vessel is dictated by the flame reaching the vessel wall, while at low concentrations the maximum pressure is dominated by the pressure (i.e., burn-up) in the discharge duct. There is an approximately linear correlation between the maximum pressure and the average flame velocity in the discharge duct for a given powder concentration, and a linear relationship between the maximum pressures in the vessel and the duct independent of the SBC concentration. Through the analysis of the flame dynamics (e.g. flame morphology, flame propagation velocity and turbulence) and friction resistance induced by the varying duct scales, the suppression efficiency of SBC powder in the vessel is higher for a longer and narrower discharge duct.

Considerations on Water Supply Pumping Station Operation in the Context of Sustainable Development

Water and energy are among the most valuable resources worldwide, therefore specialists have to focus on technical means that enable better use thereof, also with respect to safety and efficiency. The study presents the operation efficiency improvement of a newly modernised water supply pumping station in Galesu irrigation system in the Dobrogea region, Romania. The technical measures led to a decrease of electrical power requirements by about 30%. A thorough study on the hydraulic shock pointed out the best protection solution provided with low-cost devices. A numerical simulation, conducted by the use of a noncommercial software, allowed to conduct a comparative study of the pressure field in different protection scenarios. The simulation showed no dangerous high-pressure values, but it revealed the occurrence of cavitation during hydraulic shock when the ducts have no protection devices. Simple protection solutions were compared, such as a two-stage closure of the check valve on the discharge duct and one or two air valves mounted in the most vulnerable cross sections of the discharge duct. The best protection was provided by a combination of these simple means.

Nipple discharge: The state of the art.

Over 80% of females experience nipple discharge during their life. Differently from lactational (milk production) and physiological (white, green, or yellow), which are usually bilateral and involving multiple ducts, pathologic nipple discharge (PND) is a spontaneous commonly single-duct and unilateral, clear, serous, or bloody secretion. Mostly caused by intraductal papilloma(s) or ductal ectasia, in 5-33% of cases is due to an underlying malignancy. After clinical history and physical examination, mammography is the first step after 39, but its sensitivity is low (7–26%). Ultrasound shows higher sensitivity (63–100%). Nipple discharge cytology is limited by a false negative rate over 50%. Galactography is an invasive technique that may cause discomfort and pain; it can be performed only when the duct discharge is demonstrated at the time of the study, with incomplete/failed examination rate up to 15% and a difficult differentiation between malignant and benign lesions. Ductoscopy, performed under local anesthesia in outpatients, provides a direct visualization of intraductal lesions, allowing for directed excision and facilitating a targeted surgery. Its sensitivity reaches 94%; however, it is available in only few centers and most clinicians are unfamiliar with its use. PND has recently emerged as a new indication for contrast-enhanced breast MRI, showing sensitivity superior to galactography, with an overall sensitivity up to 96%, also allowing tailored surgery. Surgery no longer can be considered the standard approach to PND. We propose a state-of-the art flowchart for the management of nipple discharge, including ductoscopy and breast MRI as best options.

An Experimental Investigation of Convergent Rectangular Surface Jets: Spreading Characteristics of Horizontal Flow over the Bed of Deep and Stagnant Ambient Water

This study simulated the operation of discharge ducts in desalination plants to examine the effects exerted by the convergence and longitudinal slope of discharge channels on the spreading of horizontally flowing convergent and inclined rectangular surface jets over the bed of deep and stagnant ambient water. To this end, a 3.2 × 0.6 × 0.9 m3 flume was used, and rectangular channels with convergence angles of 12.5°, 25°, 45°, and 90° were designed. The used jet fluid was a salt water solution with a concentration of 45 g/L. The channels were activated to discharge jet fluid tangentially at a constant depth of 0.7 m into the ambient water surface. After the experiments, data analysis was carried out through image routing. Results indicated that flow distribution over the bed was circular and elliptical. The relationship between radial distance from the impingement point to the outer boundary of flow and time was determined to a power of 0.45 under discharge conditions without a longitudinal slope and to powers of 0.57 and 0.42 under discharge conditions characterized by an inclined slope. Finally, the spreading coefficients of the jets at average, major, and minor radial distances are 4, 2, and 4.5, respectively.

A study on Zone Heating Technology for Cherry Tomato by Using a Hot Water Pipe and Blowing Fan

In this study, a hot water pipe and a blowing fan were combined for developing zone heating technology for cherry tomato. The concept of this system was that hot air was firstly made by hot water pipe in one layer plastic duct and then a blowing fan made the hot air formed in a duct discharge through a duct hole to a shoot apex or a flower cluster which was temperature-sensitive part of cherry tomato. This system mainly consisted of hot water boiler, thermal tank, heat radiation plastic duct with the function of moving up and down electrically depending on the height of shoot apex. Developed system was applied to the cherry tomato greenhouse located in Jangam Chungcheongnamdo from Dec. 28, 2015 to Feb. 16, 2016 and compared with conventional entire space heating system of cherry tomato greenhouse and looked into cumulative yield for the estimate of growing state and energy saving rate from the conventional consumed energy. The result showed that cumulative yield was 3% higher and consumed energy was 32% lower than those of control greenhouse. The average temperature of shoot apex zone was 0.4~1.1℃ higher and the average relative humidity of shoot apex zone was 2,2~2.3% lower than those of entire space during night time in a shoot apex zone heating greenhouse and the average temperature of shoot apex zone was 0.7~1.4℃ lower and the relative humidity of shoot apex zone was 2.9~8.3% higher than those of entire space during night time in a entire space heating greenhouse.

215. Colour inking of breast wide local excision specimens in theatre: Time economy for the surgeon looking to improve departmental pathology diagnostics

Background: Nipple discharge has a known association with breast cancer, determing which cases to identify as being at high risk is a complex task for the clinician. The current policy at West Herfordshire hospital NHS Trust is to offer microdochectomy to all women who present with unilateral single duct nipple discharge, dominant duct discharge, or persistent duct discharge. The aim of this study was to determine if on basis of the pattern of nipple discharge, patients could be subselected for microdochectomies, and to create a base line to allow future subselection of patients for surveillance only Methods: All patient with single duct unilateral spontaneous nipple discharge, who underwent microdochectomy, were assessed. Demographics, clinical presentation, radiological assessment, cytology, core biopsy. This group of patients was analysed and correlated with their final histological assessment. Results: 122 patients were analysed in this study. 7 ( 5.74%) were diagnosed with carcinomas. 4 patients had ductal carcinoma in situ, three patients had dutcal carcinoma in situ and invasive ductal carcinoma, of these two patients had blood stained nipple discharge. Two other patients had papillary carcinomas, one patient of these two had blood stained nipple discharge. 47 out of 122 patient presented with history of blood statined discharge, 30 were negative for cytology, two patients had (ductal carcinoma in situ with Invasive ductal carcinoma and papillary ca) at final histololgy. 17 of the 47 showed cellular cytology, and one patient had intermediate grade DCIS confirmed on final histology, whereas in the remaining sixteen patients histological features of papillomas, duct ectasia, and benign breast disease was noted. Of the 122 patient 42 patients had mammary duct ectasia (34%), 52 patients had papillomas (42%) at final histology. Conclusions: The negative predictive value (2/30), appears in this series appears to be more valuable than, the positive predictive value (1/17) in cellular smears to predict ductal carcinoma or invasive ductal carcinoma. Cytological assessment of nipple discharge is equivocal at its best. Microdochectomy perford for nipple discharge results in a low rate of malignancy on excision and is comparable with other series. No conflict of interest.

PIV measurements of the unsteady flow structures in a volute centrifugal pump at a high flow rate

An experimental investigation based on PIV measurements is presented on the unsteady flow in a centrifugal pump with vaneless volute. The study has focused on the fluid–dynamic interaction between impeller and volute associated with the blade passage period when the pump operates well above design conditions (150 % of nominal flow rate). The test pump, which is fully transparent, has a 2D-shaped geometry and the impeller has 6 arc-shaped backward-curved blades. The flow in the mid-plane perpendicular to the pump axis was captured using fluorescent seeding particles and two fields of view (FOV), each with different magnification: a large FOV (low magnification) that covers a large portion of the impeller, volute and discharge duct, and a small FOV (high magnification) to observe the details of flow evolution at the tongue region. Results are presented on the in-plane phase-averaged relative and absolute velocities, turbulent kinetic energy, its production and vorticity fields. Their evolution over time during one blade passage is described, including a frequency analysis based on 32 blade positions. The spatial distribution of the spectral components at the blade-passing frequency and some harmonics reveals that the second harmonic is dominant in the narrow region of the volute at the tongue tip. The data obtained show that the fluid–dynamic blade–tongue interaction is dominated by high-vorticity sheets (positive and negative) being shed from the impeller channels, especially from the blade trailing edges, and their impingement on the tongue tip with subsequent cutting and distortion. The turbulence production is seen to be mainly concentrated in the wake regions from the blade leading and trailing edges and from the tongue tip. In particular, it gets maximum behind the blade trailing edge when the blade aligns with the tongue tip.

Nusselt Correlations in a Trailing Edge Cooling System with Long Pedestals and Ribs

Detailed TLC measurements have been carried out to estimate the heat transfer coefficient in stationary conditions under high Reynolds numbers in a trailing edge cooling system of a high pressure gas turbine blade. The investigated geometry consists of a 30:1 PMMA scaled model reproducing the typical wedge-shaped discharge duct of a trailing edge cooling system with one row of 7 enlarged pedestals. The section of the channel upstream the pedestal region is used to guide the airflow from the radial hub inlet to the tangential trailing edge outlet; in this section three different surfaces have been studied: one is smooth and the other two are ribbed with +60° and -60° angled ribs respect to the radial direction. This work focuses on the pedestal outlet section, by giving a correlation of the variation of the Nusselt number as a function of the Reynolds number, from 10000 to 40000, in the different inter-pedestal regions along the radial direction. These correlations give the regionally averaged heat transfer coefficients, from the hub to the tip of the model for both smooth and ribbed cases. The interest of these results is the use for the design of the trailing edge blade cooling systems, under the investigated Reynolds number range, that it is the typical case of the industrial application.

Detailed investigation of flame transmission from a vessel to a discharge duct

The present paper deals with a problem of explosion initiated in a vessel and vented through a duct. On the basis of numerical simulation (CFD) and visualization by means of high speed camera it completes and discusses the existing results and hypotheses (especially those presented in the work of Ponizy and Leyer [1]) concerning the process of enhancement of vessel pressure rise during such an explosion. In particular, numerical simulation indicates that a secondary explosion in the duct, known as a “burn-up”, which is responsible for higher reduced explosion pressures during ducted venting, has its source in a highly turbulent zone generated at the duct entrance by the flame itself independently of the shape of the vessel/duct passage. Camera images confirm the hypothesis that the flame penetrating into the duct is strongly torn in this turbulent zone and mixed with fresh gases. On the other hand, these images show that the reverse flow created by the burn-up returns back to the vessel some amount of rapidly burning gases, which contributes to the vessel pressure increase in the same degree that the blockage of the outflow from the vessel and the intensification of combustion of the unburned mixture previously left in the vessel.Experimental results evidence also a strong dependence of the flame behaviour in the vessel on the vessel length and the duct diameter. They demonstrate that the final effect of the burn-up action on maximum explosion pressures reached in the vessel depends on the whole process of flame propagation in the vessel, which in turn is closely related to the vessel and duct dimensions. In particular, in some configurations, an apparition of the “tulip flame” combined with inertia of the gas column in the duct may in a spectacular manner reduce the effect of the burn-up action.