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Register a new userA thermodynamic study to improve the performance of the HELANDT cycle to produce liquefied air
دراسة ترموديناميكية لتحسين أداء دورة HELANDT لإنتاج الهواء المسال
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في هذا البحث قمنا بدراسة طرق إنتاج البرودة الشديدة اعتمادا على ظاهرة جول - طومسون. و قمنا بدراسة معلقة لما قام بها الباحثون الاخرون- Claude- Kapitza HELANDT و آخرون للوصول إلى درجات حرارة منخفضة و بالتالي الى درجة حرارة تمييع الهواء اعتمادا على هذه الظاهرة و درسنا بالتفصيل مؤثرات عمليتي الخنق و التمدد و أجرينا مقارنة بينهما لجهة إمكانية استخدام كلا منهما و الشروط المثالية لاستخدام كلا منهما.
In this research, we studied the methods of cryogenics depended on Joule-Thomson effect. We studied in-depth what the other researchers( KAPITZA, CLAUDE, HELANDT and others) do to reach low temperatures and thus to the liquefaction temperature of air. We studied in detail the effects of throttling and expansion and we compared them to the possibility of use both and the ideal conditions to use both of them.
References used
BARRON R F ,1111“CRYOGENIC SYSTEMS‟, SECOND EDITION, NEW YORK, OXFORD UNIVERSITY PRESS
Timmerhaus,K.D. and Flynn T.M,Cryogenic 1989. Process Engineering Plenum Press
YVONNE LIM, MUSHTAK AL-ATABI, RICHARD A. WILLIAMS, 2016 LIQUID AIR AS AN ENERGY STORAGE JOURNAL OF ENGINEERING SCIENCE AND TECHNOLOGY,VOL. 11. 496 – 515
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evaporator within hot water tank which acted as a water heat source of the heat pump. We
made the heat pump to run alternatively either using surrounding air heat or
water heat
gained from solar power.
We have done experiments during five months starting in December of 2014 until
April 2015. Temperature and pressure were measured at specific points of the cycle. Then
we defined the enthalpy at each point for both cycles using EES software (which is a
software to simulate thermodynamic elements)، and calculated the amounts of heat gained
in the evaporator، heat charged from the condenser، compressor work، coefficient of
performance ، and electrical power consumed by the compressor.
Then we made a compare between the two cycles and found that the improvement
ratio in of the modified cycle to the traditional cycle was 77.07%، and the reduction
ratio in electrical power consumed by the compressor of the modified cycle was 33.54%.
The study suggests designing a weighting model for iris features and selection of the
best ones to show the effect of weighting and selection process on system performance.
The search introduces a new weighting and fusion algorithm depends on the i
nter and intra
class differences and the fuzzy logic. The output of the algorithm is the feature’s weight of
the selected features. The designed system consists of four stages which are iris
segmentation, feature extraction, feature weighting_selection_fusion model
implementation and recognition. System suggests using region descriptors for defining the
center and radius of iris region, then the iris is cropped and transformed into the polar
coordinates via rotation and selection of radius-size pixels of fixed window from center to
circumference. Feature extraction stage is done by wavelet vertical details and the
statistical metrics of 1st and 2nd derivative of normalized iris image. At weighting and
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distance classifier. The algorithm is applied on CASIA database which consists of iris
images related to 250 persons. It achieved 100% segmentation precision and 98.7%
recognition rate. The results show that segmentation algorithm is robust against
illumination and rotation variations and occlusion by eye lash and lid, and the
weighting_selection_fusion algorithm enhances the system performance.
The purpose of this research is to study the improvement of soil properties by the
addition of lime in certain percentages. The soil used in this study was obtained from the
Baseet region, which is located by the Syrian coast. We have studied the e
ffect of lime on
the consistency, the swell characteristics and the shear strength of soil.
The results of this study have shown a remarkable reduction of both liquid and
shrinkage limits, and the plasticity index with the increase of lime percentage. As for
plasticity limit, it increases in the beginning then decreases slightly with the rising of lime
percentage.
For the volumetric variation, the susceptibility of swelling and the shrinkage of
improved soil with lime decrease, and the free swelling and the swelling pressure become
almost negligible with 4% of lime.
Based on the shear strength results, we can indicate a notable increase in the friction
angle and cohesion of soil with increasing of lime percentage up to 8% of lime. After that,
these two factors decrease.
The Research aimed to use the technology of the fermentation to produce the biogas from the cow manure. The digester has benn carried according to the Indian model. The digester consit of one cylinerical tank with 9.42m3 volume (height 3m, diameter 2
m) and gastank with 6m3 (height 1m) and inlet pipe and outlet pipe. The study showed the following:
The accumulated production of biogas was through the 30 days retention time 48m3. The heighest production was in the thirteenth day with 4.5m3. The farm became after the use of digester clean and with little insect and smell.
With use 1m3 of biogas could we use one cooker for 2.5 hour and with the same quantity could we use one inner combustion diesel motor (90% biogas and 10% diesel) for half an hour.
3/4m3 from digester volume is enough for one cow with 12 kg manure daily. So we can design the suitable digester for any farm.
The aim of this study is investigate in using refrigerants mixtures as substitute to
R134a in a testing compression refrigeration cycle designed to work with a mass of 100g
of R134a without make changing or modification in the cycle. The new mixtur
e that made
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properties was compared with R134a on the same conditions and on different evaporation
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This study support possibility of using refrigerant mixtures in refrigeration cycle that
designed to work with pure refrigerant (single component) without making any change in
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thermodynamic properties and environmentally friendly like Propane and butane but there
are some warning from using it because their flaming.
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