PARTICULATE FOULING GROWTH RATE AS INFLUENCED BY THE CHANGE IN THE FOULING LAYER STRUCTURE

Particulate fouling in biomass gasifiers is a majorproblem, which may lead to inefficient operation. As the fouling layer grows, its thermal resistance increases resulting in an increase in the surface temperature of the fouling layer. The increase in the fouling layer surface temperature can lead to sintering of the layer, which changes the layer structure from a fragile powder to a robust coherent structure. The influence of the change in the fouling layer structure on the growth rate of particulate fouling is studied experimentally. Impaction experiments were carried out to determine the velocities at which an incident particle sticks, bounces off or removes particles outof the fouling layer as a function of fouling layer structure. The sticking velocity of a particle hitting a clean tube is determined theoretically. The sticking velocity of a bronze particle hitting a bronze plate is 0.006 m/s, for a powdery layer is 0.3 m/s and for a sintered layer is 0.04 m/s. The change in the heat exchanger surface from solid to powdery increases the sticking velocity, which consequently speeds up the fouling process. The further change in the heat exchanger surface from powdery to sintered decreases the sticking velocity, which reduces back the fouling process. The change in the fouling layer structures affects the sticking velocity as well as the removal velocity of incident particles, which consequently affect the fouling process

Removal of Particles from a Powdery Fouled Surface due to Impaction

Particulate fouling is defined as the unwanted deposition of particles on heat exchange surfaces. The fouling layer reduces the heat transfer rate and leads to inefficient operation. The net fouling rate is the result of the difference between the deposition rate and the removal rate of particles. One of the mechanisms that contribute to the removal of particles from powdery fouled surfaces is the collision of an incident particle with the fouled surface. In the present study, removal of particles from powdery fouled surfaces due to an incident particle impact is studied numerically and experimentally. A numerical model is developed to study the interaction of an incident particle with a bed of particles. The numerical model is based on the molecular dynamic theory of granular matter. The numerical model is tested for an incident copper particle hitting a bed of particles at different impact speeds. The numerical results are verified experimentally. An experimental setup has been built to study the removal of particles from powdery fouling layers due to an incident particle impact. It is shown that depending on the impact speed, zero, one, two or three particles are ejected from the powdery layer. By comparing the numerical results with the experimental measurements it is shown that the numerical results fit in the measured range of impact mentioned above. The numerical model will be used further to characterize the removal of particles from powdery fouling layers as function of particle size, material, incident particle impact speed and the bed of particles porosity

Finite element analysis of the behavior of bonded composite patches repair in aircraft structures

This paper aims to analyze the multi-effects of the glass fiber reinforced polymer (GFRP) composite patch to repair the inclined cracked 2420-T3 aluminum plate. Three-dimensional finite element method (FEM) was used to study the effect of GFRP composite patch with different stacking composite laminate sequence, [0°]4, [90o]4, [45o]4, [0o/45o]2s and [0°/90°]4s on the crack driving force, J-integral, of inclined cracked 2420-T3 aluminum plate. Furthermore, the effects of patch geometry, number of layers, single or double side patch and crack incline angle are described. The present results show that the patch has a high effect in case of a crack in pure mode I. Furthermore, the effectiveness of the composite patch is increasing with the crack length increases. Moreover, the efficiency of the composite patch has a high effect by changing the fiber orientation, the number of layers, and the single or double side patch

Effect of Protocol of Care on Clinical Outcomes of Patients with Chest Tube Post Cardiothoracic Surgery

Cardiothoracic surgery is a surgical specialty, which deals with the diagnosis and management of surgical conditions of the heart, lungs and esophagus (1) .Chest tube (CT) is an invasive procedure which inserted post cardiothoracic surgery to facilitate lung expansion and allowing  the drainage of fluids from the chest cavity. Aim: this study aimed to evaluate the effect of protocol of care on clinical outcomes of patients with chest tube post cardiothoracic surgery. Materials and method a quasi-experimental research design was conducted at Cardiothoracic Surgery Department at Tanta University hospital. A purposive sample of 80 adult patients with chest tube based on statistical power analysis were selected and divided into two equal group 40 patients in each group as follows: Group 1: (Study group): consist of 40 adult patients were received protocol of care implemented by the researcher. Group 2: (Control group): consists of 40 adult patients who were received routine nursing care by hospital nursing staff. Three Tools were used to collect the data .Tool (I) Biosocio-demographic characteristics. Tool (II) Chest tube assessment, Tool (III) Pain assessment. Results:- The mean duration of ICU stay in control group (6.77) was higher than in the study group (4.97) days, more than half (52.6%)of the patients in the control group at the 7th day of the study had elevated body temperature comparing to none  in the study group, nearly two third (62.5%) of patients has  a positive culture swab in the control group at the  7th day of the study group ,compared to about  third(35%) of patients in the study group. More than half of patients (52.5%) in the control group had a severe pain during removal of chest tube compared to small percentage (5.0%) in the study group. Conclusions and recommendations:-Protocol of nursing care which was composed of deep breathing and coughing   exercises, sterile technique during chest tube dressing, and cold application, are recommended for all cardiothoracic surgical patients with chest tube. Keywords: Protocol of Care, Clinical Outcomes, Cardiothorathic Surger

EFFECT OF IRRIGATION LEVELS AND FOLIAR SPRAYING WITH SEAWEED EXTRACT, POTASSIUM SILICATE AND ABSCISIC ACID ON GROWTH, CORM YIELD AND QUALITY OF TARO

The field experiment was established at the experimental farm of the Horticultural Research Station of Barrage, Qalyubia Governorate during 2014 and 2015 growing seasons to evaluate the impact of irrigation levels i.e.,120, 100, 80 and 60% of the evapotranspiration (ETc) and stress alleviation substances (seaweed extract, potassium silicate and abscisic acid against control treatment) on growth, corm yield and quality of taro (Colocasia esculenta cv. Balady), with a particular attempt  to establish irrigation water strategy for taro cultivation. The results indicated a reduction in plant growth and corm yield as well as quality due to minimizing irrigation level from 120 to 60% ETc. But the highest water use efficiency (WUE) was obtained with 80% irrigation level. Seaweed extract showed a superior enhancement in all measured vegetative, yield and quality parameters followed by potassium silicate compared to abscisic acid or control. Seaweed extract heightened the WUE compared to other substances. Results concluded that using 80% irrigation level accompanied by spraying plants with seaweed extract  led to a mild reduction in the plant growth, yield and quality but conferred the higher WUE compared to other interactive treatments

Dual Sized Varying Slot Lengths Loading Dielectric Resonator Reflectarray

Abstract A reflectarray antenna consists of elements of rectangular dielectric resonator (DRA) with slot loading of different lengths is proposed for bandwidth enhancement. Two DRA sizes an two slot widths are available to tune the phase of each element in the reflectarray so that a full 360 degrees phase shifts can be achieved by superposition. Two structures are presented in that paper. The first is center fed reflectarray while the second is offset fed for decreasing the feeder blockage. The antenna has 10% bandwidth for 1 dB gain variation is obviously wider than that of conventional reflectarray antenna while the offset fed reflectarray provide better far field pattern with back lobes reduction by -5 dB and side lobe by -2 dB. A pyramidal X-band horn was used in both reflectarrays which have 23 x 23 elements of with cells separation of 12 mm that less than 15 mm (lambda/2) for avoiding grating lobes. The analyses are carried out using the finite integration technique (FIT) and the transmission line method (TLM) with good agreements between them

Power frequency AC voltage measurement based on double wound Rogowski coil

This study presents a technique for power frequency AC voltage measurement. The proposed technique utilises a capacitor having a low capacitance in addition to a double wound Rogowski coil. This technique depends on capacitor current measurement using the double wound Rogowski coil. The voltage across the capacitor that connected in parallel with the system at which AC voltage is intended to be measured is reconstructed. The proposed technique is experimentally evaluated by designing the measurement system and using a digital signal processing board for the reconstruction processes. Moreover, the experimental results based on Rogowski coil measurements are compared with those obtained from reference techniques. Finally, the obtained results validate the efficacy of the proposed technique in power frequency AC voltage measurement

Improving the performance of evacuated tube heat pipe collectors using oil and foamed metals

The objective of this research is to improve the heating capability of evacuated tubes that comprises heat pipes. Thermal oil is inserted in the evacuated tube in order to improve the rate of heat transfer, such that the mode of heat transfer from the inner surface of the evacuated tube to the heat pipe becomes convection via the oil, as well as conduction through the installed fin. The finned surface has been replaced by a foamed-copper. An experimental setup has been developed to study the influence of oil and foamed metals on the performance of evacuated tubes with heat pipes. It has been found that the bulb temperature as well as the heating efficiency of the evacuated tube heat pipe has increased in case of inserting oil in the evacuated tube and replacing the finned surface with foamed copper. Also, the thermal oil acts as a heat storage. Keywords: Evacuated tube, Heat pipe, Energy storag