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Register a new userEffect of Absorber surface shapre on the forced thermal convection of solar air collections
تأثير شكل السطح الماص على الحمل الحراري القسري لمجمعات هوائية شمسية
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Added by
Tishreen University ورقة بحثية
Publication date
2010
fields
Mechanical Engineering
and research's language is
العربية
Authors
عامر جميل شريف( باحث )
Created by
Shamra Editor
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يضمن البحث دراسة تأثير شكل اللوح الماص (المستوي، المتعرج، المتموج والمستطيل) لمجمع هوائي شمسي طوله وعرضه واحد متر وسمكه 0.1 متر مائل عن الأفق (٣٠ درجة) على معامل انتقال الحرارة بالحمل القسري معامل الاحتكاك السطحي عند فيض حراري شمسي ثابت (530 w/m2) ولمدى عدد رينولد (5000 <= Re <= 8000). تم استخدام البرنامج العددي Fluent في الدراسة الحالية حيث تم حل المعادلات التفاضلية الحاكمة (معادلة الاستمرارية الزخم والطاقة) بطريقة الحجوم المحددة مع الأخذ بعين الاعتبار ان الجريان مضطرب ثنائي البعد للحالة المستقرة.
In this research a study effect of absorbed surface shape for solar air collector (Flat V-Corrugated ,Sinusoidal Wave-Corrugated ,Rectangular-Corrugated) titled to the horizontal by an angle(30) on forced heat transfer and skin friction coefficient by Fluent Numerical Program at constant solar heat flax (530W/m2) with Reynold’s number (5000≤Re≤8000). The government equation (mass, momentum and energy) are using Finite Volume by (Fluent 6.3) software for considering steady state, two dimensional and turbulent flow. The results show that the different between inlet and outlet air temperature is(13.65oC) and best heat transfer coefficient enhancement is(63%) for (V-Corrugated plate) compared with the flat plate at (Re=8000). Also the results show that the maximum skin friction coefficient is occurred at (V-Corrugated) Cf=0.22 at (Re=8000).
References used
Alison Mason, Fort Collins, Jim Welch, Cindy Kline Isenhour Richard “Solar Air Heating on Ridge Indian Reservation Promising Application of a Tried and True Solar Technology ”
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Direct steam generation in parabolic trough collector (DSGPTC)
has had a great importance because of its thermoeconomic
advantages and many researches have be done in
this field. Due to that reason this paper studies the convection
heat transfer
from absorber tube of a PTC to all phases of
water (liquid water, wet steam and dry steam) along the
whole distance of fixed length of a DSG-PTC generates a high
temperature superheated steam (561 °C). All heat transfer
operations in PTC has been modelled and then the
convection' components which are; fluid temperature, tube
wall-fluid temperatures difference and heat transfer
coefficient have been analyzed in details at different
operation conditions such as inlet fluid pressure, direct solar
beam and mass flow.
Large language models have shown promising results in zero-shot settings. For example, they can perform multiple choice tasks simply by conditioning on a question and selecting the answer with the highest probability. However, ranking by string proba
bility can be problematic due to surface form competition---wherein different surface forms compete for probability mass, even if they represent the same underlying concept in a given context, e.g. computer'' and PC.'' Since probability mass is finite, this lowers the probability of the correct answer, due to competition from other strings that are valid answers (but not one of the multiple choice options). We introduce Domain Conditional Pointwise Mutual Information, an alternative scoring function that directly compensates for surface form competition by simply reweighing each option according to its a priori likelihood within the context of a specific task. It achieves consistent gains in zero-shot performance over both calibrated and uncalibrated scoring functions on all GPT-2 and GPT-3 models on a variety of multiple choice datasets.
Electric energy is very important for sustaining the good life on the planet's surface, especially since civilization has become associated with this type of energy. Solar photovoltaic (PV) is one of the most suitable applications for converting sunl
ight into electrical energy. The appropriate use of solar energy is an important topic for reducing dependence on fossil energy sources that are used to generate electricity, and thus reducing the emissions of greenhouse gases on the planet's surface. Globally, because of environmental conditions, other methods of generating energy being searched for that are less harmful than traditional methods, which rely on a large percentage of them on generating stations that run on fossil fuels. This research discusses electrical power generation using solar energy cells and the effect of these cells on the Syrian electrical grid so that a study of a solar energy farm project provides the data required when working on implementing such a project, and these data are voltage control, load flow, total harmonic distortion coefficient levels. To implement such a project, the model must be designed and we chose the ETAP program for that.
Background & Objective: Spray drying techniques are used to produce inhaled powders of enzymes and proteins without denaturation. The surface free energy data of these powders is used to reduce the time of formulation development. During storage, the
surface free energy of the inhaled protein powders could change and so their performance will be affected. Many factors affect the limit of this change. Storage temperature is the critical factor.
Material& methods: A spray drying method was optimized to prepare inhaled spray dried lysozyme powders. Inverse gas chromatography was utilized to measure the surface free energy of the prepared powders pre and post-storage to detect the effect of storage temperature on the surface free energy.
Differential Scanning Calorimetry and biological activity tests were used to evaluate the integrity of lysozyme conformation after storage at different storage temperature.
Results: Increasing the storage temperature decreased both dispersive and specific surface components of the spray-dried lysozyme powders significantly (ANOVA: P < 0.001) up to 12% and up to 31 % after storage for one year at 40 °C, respectively. The overall decrease in the polar components resulted in a
reduction of the surface basicity. These decreases in the surface energetics would be due to the aggregation of denatured lysozyme molecules at the powder surface via hydrophobic regions rich with electrons. The same results were found after storage for one year at room temperature, but the extents of
changes were smaller.
Conclusion: It is advisable to store protein powders at 5°C to inhibit the changes in their surface free energy which is the crucial factor affecting their performance.
Background
Resin bonded fixed partial dentures appeared to prevent the excessive preparation of dental
tissue
Investigation of surface treatments to improve the bond of resin cements to metals may contribute
to the longevity of these restoration
s. Due to the potential lack of ideal preparation form the type of alloy
and its surface pretreatment may have clinically relevant correlations with the retentive strength of castings
to minimally retentive preparations
Aim
The aim of this search is to study the bonding resin cement strength to different types of the metal
alloy due to the surface treatment
Purpose Evaluate the effects of two different surface treatments on shear bond strength SBS between a
palladium silver alloy Pb Ag and commercially pure titanium CP Ti cast alloy with resin luting cements
metal type
تأثير نوع المعدن
ومعاملة السطح على مقاومة القص لارتباط الإسمنت الراتنجي
الإسمنت الراتنجي
shear bond strength of resin
خليطة بلاديوم
فضة ( Pb-Ag)
التيتانيوم النقي تجاريا (CP Ti)
المهيئ المعدني (MZP)
Commercially pure titanium
metal zirconia primer
palladium‑silver alloy
resin cement
sandblasting
المزيد..
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