Numerical study of a regenerative counter flow evaporative cooler using alumina nanoparticles in wet channel

The use of Maisotsenko Cycle (M-Cycle) has enhanced the domain of evaporative cooling technologies to sub-wet bulb temperature cooling while ensuring moisture control. Several studies have demonstrated the use of cross-flow heat & mass exchanger (HMX) offers higher cooling capacity; however, it has lower cooling effectiveness and Energy Efficiency Ratio (EER). In contrast, a counter-flow (HMX) offers high cooling effectiveness with lower cooling capacity. In this paper, the performance of counter-flow HMX is enhanced by addition of alumina nanoparticles in feed water due to enhanced heat and mass transfer characteristics of nanofluids compared to original base fluid. Here, a mathematical model is formulated by incorporating the nanofluids in a selected control volume. The developed model is solved numerically on a discretized HMX length. Initially, the model is benchmarked against previously published results using water as base fluid. A comparison between HMX performance using water and alumina nanofluid is performed in terms of Performance Enhancement Ratio (PER). PER indicates 1-18% increase in cooling effectiveness, 18-43% increase in cooling capacity and 9-19% increase in EER by using alumina in water when working air temperature is increased from 20°C to 45°C. Similarly, an increase in PER is also observed by changing air velocity. Increase of 41% is observed in cooling capacity and 18% increase in EER is observed by changing particle volume fraction from 0 to 2 percent. This research identifies ways to reduce the carbon emissions of a building by increasing the energy efficiency of existing evaporative cooling technology using nanofluids

Thermal performance enhancement of a cross-flow-type maisotsenko heat and mass exchanger using various nanofluids

© 2018 by the authors. The incorporation of a Maisotsenko (M) Cycle into an indirect evaporative cooler has led to the achievement of sub-wet bulb temperature without any humidification, thus making it a possible green and sustainable alternative for handling the cooling load of a building. In this work, the thermal performance of a cross-flow heat and mass exchanger (HMX) is enhanced by the addition of nanoparticles in the wet channel because they significantly influence the heat and mass transfer characteristics of the base fluid. A governing model for the temperature and humidity variations of the HMX is numerically simulated. Initial benchmarking is achieved using water properties. Afterward, a comparative study is conducted using aluminum-oxide-, copper-oxide-, and titanium-oxide-based nanofluids. Enhancements of 24.2% in heat flux, 19.24% in wet bulb effectiveness, 7.04% in dew point effectiveness, 29.66% in cooling capacity, and 28.43% in energy efficiency ratio are observed by using alumina-based nanofluid as compared to water in the wet channel of the cross-flow HMX. Furthermore, a particle volume concentration of 1% and a particle diameter of 20nm are recommended for maximum performance

Kerosene-Water Multiphase Flow in Vertical and Inclined Pipes

This chapter presents the volume fraction distribution of kerosene-water two-phase flow in vertical and inclined pipes. The study of liquid-liquid two-phase flow is very significant to oil industry and many other processes in industry where two liquids are mixed and flow together. Pitot tube and optical probes are used for the measurement of velocity of water and volume fraction. The experimental measurements of the local parameters demonstrate that the single-phase and two-phase flows reached the fully developed axisymmetric conditions at L/D ≥ 48 (L, pipe length; D, pipe diameter). The results also showed the severe asymmetry distributions of the volume fraction at the entrance region (L/D = 1) downstream the bend and in the inclined pipe. The comparison of volume fraction profiles with void fraction profiles indicated a significant difference in their shapes. The results also showed that the kerosene accumulated at the upper wall of the inclined pipe and the distribution improved by increasing the volumetric quality

Numerical Analysis Of Swirl Intensity In Turbulent Swirling Pipe Flows

Swirling flows are often observed in nature such as weather systems, cyclones and tornados. A number of applications use swirling nature of flow for enhanced mixing, heat transport and other transport phenomena. Naturally occurring swirls as well as induced swirls are often usually turbulent in nature. Understanding the flow physics of turbulent swirling flow is important for better understanding and control of processes involving swirling flows. With the increase of computational resources and advancements in turbulent flow modelling, it is now possible to simulate highly complex flow structures. Here turbulent swirling flow induced by guide vanes is studied using Computational Fluid Dynamics (CFD) simulations in a two-dimensional axisymmetric channel. The results for the variation of velocity components are compared with the work of an earlier research. The results are initially compared for the evaluation of best discretisation scheme. It was observed that the second-order and third-order schemes produced similar results. To simulate the turbulent flow two equations (k-ε) model and the five equations Reynolds Stress Model (RSM) are used. The comparison of both models with higher order discretisation schemes shows that the standard k-ε model is incapable of predicting the main features of the flow whilst RSM yields result close to the experimental data

Occipital Encephalocele and Review of Literature

Encephalocele is a rare congenital malformation of the central nervous system. It is defined as a congenital herniation of the intracranial compartments through a long defect and contains various rudimentary cerebral tissue components or sometimes only cerebrospinal fluid. They are located at midline of parietal or occipital region when the defect is small. Usually only the meninges herniate and the anomaly is cranial Meningocele or cranium bifidum with Meningocele. We present 47 cases of encephalocele, mostly occipital encephalocele, operated during last 5 years in our hospital at the department of Neurosurgery SZH, RYK. This is a retrospective study.Material and Methods: Between January 2008 and December 2013. Forty seven cases of encephalocele have been treated at our department. They were diagnosed on the basis of clinical findings and CT scan was done in all patients. All patients were operated and diagnosis was confirmed at peroperatively. Demographic, clinical, radiological and operative data were reviewed from hospital charts.Results: The total number of patients was 47, out of which 23 were male and 24 were female. Neurosurgical data of patients with encephalocele over the five years and three months from January 2008 to April 2014 were retrospectively studied. The average age of the patients at the time presentation was 10 months and seven days.Conclusion: Encephalocele is a relatively uncommon neurosurgical entity largely seen in the pediatric population. Treatment of this condition can be rewarding if properly managed early. Occipital, parietal, frontal, and frontonasal types may be approached without opening the cranium, while sincipital and basal encephalocele usually require craniotomy. In this series we present our experience in the operative management of encepha-locele with good outcome and also share our recommendation in technical consideration for surgical approaches

Changes in gene expression of DOR and other thyroid hormone receptors in rat liver during acute-phase response

Non-thyroidal illness is characterized by low tri-iodothyronine (T3) serum level under acute-phase conditions. We studied hepatic gene expression of the newly identified thyroid hormone receptor (TR) cofactor DOR/TP53INP2 together with TRs in a rat model of aseptic abscesses induced by injecting intramuscular turpentine-oil into each hind limb. A fast (4-6 h) decrease in the serum level of free thyroxine and free T3 was observed. By immunohistology, abundant DOR protein expression was detected in the nuclei of hepatocytes and ED-1+ (mononuclear phagocytes), CK-19+ (biliary cells), and SMA+ (mesenchymal cells of the portal tract) cells. DOR signal was reduced with a minimum at 6-12 h after the acute-phase reaction (APR). Immunohistology also showed a similar pattern of protein expression in TRα1 but without a significant change during APR. Transcripts specific for DOR, nuclear receptor co-repressor 1 (NCoR-1), and TRβ1 were down-regulated with a minimum at 6-12 h, whereas expression for TRα1 and TRα2 was slightly and significantly up-regulated, respectively, with a maximum at 24 h after APR was initiated. In cultured hepatocytes, acute-phase cytokines interleukin-1β (IL-1β) and IL-6 down-regulated DOR and TRβ1 at the mRNA level. Moreover, gene expression of DOR and TRs (TRα1, TRα2, and TRβ1) was up-regulated in hepatocytes by adding T3 to the culture medium; this up-regulation was almost completely blocked by treating the cells with IL-6. Thus, TRβ1, NCoR-1, and the recently identified DOR/TP53INP2 are abundantly expressed and down-regulated in liver cells during APR. Their down-regulation is attributable to the decreased serum level of thyroid hormones and most probably also to the direct action of the main acute-phase cytokines

A case of finger clubbing associated with nasopharyngeal carcinoma in a young girl, and review of pathophysiology

Hypertrophic osteoarthropathy is characterized by clubbing of the digital tips and periosteal reaction of long bones. Most of the cases are associated with malignancy or other conditions such as congenital heart disease, liver cirrhosis, pulmonary fibrosis, biliary atresia and gastrointestinal polyps. Hypertrophic osteoarthropathy associated with malignancy is rare in children. A few cases of hypertrophic osteoarthropathy in children with nasopharyngeal carcinoma have been reported. This is a case of hypertrophic osteoarthropathy associated with nasopharyngeal carcinoma with lung and bone metastasis in a 16 year old girl. In this case, lung metastases progressed after intensive chemotherapy and hypertrophic osteoarthropathy (Clubbing) persisted

Comparison of changes in gene expression of transferrin receptor-1 and other iron-regulatory proteins in rat liver and brain during acute-phase response

The “acute phase” is clinically characterized by homeostatic alterations such as somnolence, adinamia, fever, muscular weakness, and leukocytosis. Dramatic changes in iron metabolism are observed under acute-phase conditions. Rats were administered turpentine oil (TO) intramuscularly to induce a sterile abscess and killed at various time points. Tissue iron content in the liver and brain increased progressively after TO administration. Immunohistology revealed an abundant expression of transferrin receptor-1 (TfR1) in the membrane and cytoplasm of the liver cells, in contrast to almost only nuclear expression of TfR1 in brain tissue. The expression of TfR1 increased at the protein and RNA levels in both organs. Gene expression of hepcidin, ferritin-H, iron-regulatory protein-1, and heme oxygenase-1 was also upregulated, whereas that of hemojuvelin, ferroportin-1, and the hemochromatosis gene was significantly downregulated at the same time points in both the brain and the liver at the RNA level. However, in contrast to observations in the liver, gene expression of the main acute-phase cytokine (interleukin-6) in the brain was significantly upregulated. In vitro experiments revealed TfR1 membranous protein expression in the liver cells, whereas nuclear and cytoplasmic TfR1 protein was detectable in brain cells. During the non-bacterial acute phase, iron content in the liver and brain increased together with the expression of TfR1. The iron metabolism proteins were regulated in a way similar to that observed in the liver, possibly by locally produced acute-phase cytokines. The significance of the presence of TfR1 in the nucleus of the brain cells has to be clarified

Assessment of thermo-hydraulic performance of inward dimpled tubes with variation in angular orientations

This paper presents a numerical investigation and assessment of thermal and hydraulic performance of dimpled tubes of varying topologies at constant heat flux of and Reynolds numbers ranging from 2300 to 15,000 The performance of the tubes consisting of conical, spherical and ellipsoidal dimples with equivalent flow volumes were compared using steady state Reynolds Averaged Navier Stokes simulations. The ellipsoidal dimples, in comparison to other dimple shapes, demonstrated large increment in heat transfer rate. The variation in the orientation of the ellipsoidal dimples was examined to further improve thermal and hydraulic performances of the tube. A 45° inclination angle of ellipsoidal dimple, from its major axis, increased the thermo-hydraulic performance by 58.1% and 20.2% in comparison to smooth tube and 0° ellipsoidal dimpled tube, respectively. Furthermore, Large Eddy Simulations (LES) were carried out to investigate the role geometrical assistance to fluid flow and heat transfer enhancement for the 45° and 90° ellipsoidal dimpled tubes. LES results revealed a flow channel of connected zones of wakes which maximized fluid-surface