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 |  موضوع: بحث بعنوان Theoretical and Experimental Research Work in Solar Absorption Refrigeration الجمعة 26 يونيو 2020, 12:26 am | |
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أحضرت لكم بحث بعنوان
Theoretical and Experimental Research Work in Solar Absorption Refrigeration
Fathelrahman Ahmed Elmahi 1, Osama Mohammed Elmardi Suleiman Khayal 2*
1,2 Nile Valley University, Department of Mechanical Engineering, Atbara, Sudan
e-mail: osamamm64@نص ممنوع.com
و المحتوى كما يلي :
Abstract
Solar energy can be utilized by, either,
thermal conversion, or electrical conversion, of solar
radiation. Utilization of solar energy by thermal
conversion method, is of low cost, but it requires
high density of solar radiation. Electrical conversion
method, on the other hand, is expensive, but it does
not need high density of solar radiation. One of the
most important applications of thermal conversion of
solar energy, is absorption refrigeration. As there are
many factors affecting the process of solar
refrigeration, a lot of research work must be carried
out, before deciding an optimum design of solar
refrigeration systems, which utilize solar energy at a
low cost. The main objective of this research article
is to design and construct an apparatus which can be
used, as a test rig, by research students, to carry out
experiments, regarding the performance of solar
absorption refrigeration systems. The apparatus has
been designed and constructed so as to be used
indoors. One of the many different factors which
affect the performance of solar absorption
refrigeration systems, has been chosen, to test the
apparatus, for functioning. This is the effect of
condenser temperature, on the performance of solar
absorption refrigeration systems. The apparatus has
been tested for three different values of condenser
temperature, and yielded very good results. The
experimental work proves that, the coefficient of
performance of a solar absorption refrigeration
system, is high, at a low condenser temperature. At a
condenser temperature of about 25?C, the actual
coefficient of performance, obtained is 0.019,
compared with a theoretical value of 0.062. And at a
condenser temperature of about 15?C, the
actualcoefficient of performance is 0.026, compared
with a theoretical value of 0.094
CONCLUSIONS
In this study, a computer simulation program
was written, using the FORTRAN language, to
predict theoretical performance of an intermittent
absorption refrigeration system. The program was
run for different values of performance parameters,
and gave good results. The program was able to
calculate the properties of the fluids encountered in
the experiment, and give values for different
required quantities, such as; the quantity of the
cooling water required for the absorber, the required
tube length in the generator/absorber unit, the
quantity of the cooling water required in the
condenser tank, the required length of the condenser
coil,…etc., and finally, the program gives the
valueof the theoretical coefficient of performance of
the system, according to the given input data. A
simple intermittent ammonia absorption refrigeration
system was designed and constructed in this study.
The system was designed so that, there is a single
vessel, performing both functions of the generator,
and the absorber, and, another single vessel,
performing both functions of the receiver and the
evaporator, alternatively. The system consists of the
following main components: the generator/absorber
unit, the condenser and the receiver/evaporator unit.
All the system components were designed so as to
ensure simplicity, and ease of construction and
operation of the system. They are fabricated from
steel plates, angle sections, channel sections and
tubes. Two pressure gauges were included to
indicate the pressure in the generator/absorber and in
the receiver/evaporator units. The system
components were properly assembled, and
successfully tested, for functioning, up to a pressure
of 15 bar. They showed a very good performance,
each component performed its function as
required, and no leakage was noted during the test.
The system was tested for three different values
of condenser temperature, these are 25, 20 and 15?C.
The test results showed that the coefficient of
performance of an intermittent absorption
refrigeration system is high when the condenser
temperature is low. The value of the actual
coefficient of performance, which is obtained from
the test, is lower than the theoretical value, which is
obtained from the computer program. The
difference between the two values is, largely, due to
inaccuracy in measurements, which were taken
during the experiment. The use of data logger, and
advanced measuring techniques, are recommended
for future work.
It can be concluded that, the apparatus, which has
been designed, constructed and tested in this
research, can be used successfully, to test the
performance of a solar absorption refrigeration
system, which uses aqua-ammonia solution in an
intermittent cycle. The apparatus can work safely, at
a pressure of 15 bar. This pressure corresponds to a
condenser temperature of about 30?C, It is clear that,
only slight cooling, of the condenser cooling
water, is required and, in some instances, tap water,
which is taken directly from the main supply, can be
used as a condenser cooling water. The apparatus is
also characterized by the use of an electrical
heating unit, to act as a solar collector. This enables
the apparatus to be located inside a laboratory,
instead of outdoors under the sun light, and greatly
simplifies execution of the experimental work, which
can be carried out at any time throughout a day.
This advantage becomes clear, if it is mentioned that,
some experiments may take up to 24 hours duration.
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