An experimental and theoretical analysis was conducted for simulation of open circuit cross flow heat
exchanger dynamics during flow reduction transient in their secondary loops. Finite difference
mathematical model was prepared to cover the heat transfer mechanism between the hot water in the
primary circuit and the cold water in the secondary circuit during transient course. This model takes under
consideration the effect of water heat up in the secondary circuit due to step reduction of its flow on the
physical and thermal properties linked to the parameters that are used for calculation of heat transfer
coefficients on both sides of their tubes. Computer program was prepared for calculation purposes which
cover all the variables that affect such type of transient mechanisms. The effect of the power density in
the primary circuit and the water flow reduction percentage on the average temperature build up of the
water in the primary circuit was investigated. The elapsed time required for the primary circuit average
temperature to reach a steady state value was also calculated. These calculations were supported with
experimental measurements conducted on a standard cross flow heat exchanger apparatus. The
experimental results were compared with the theoretical results for certain power density value at
different flow reduction percentages which show a reliable agreement. This relative agreement was
necessary to consider the mathematical model with certain assurance for calculating transient parameters
for higher power densities that are out of apparatus ranges. The results proved that water average
temperature build up in the primary circuit has sharp tendency when the percentage of flow reduction in
the secondary circuit reach 25% of its nominal values.
This study was carried out to measure the percentage of heavy metals pollution in the water of the Diyala river and to measure the percentage of contamination of these elements in the leafy vegetables grown on both sides of the Diyala river, which are irrigated by the contaminated river water (celery, radish, lepidium, green onions, beta vulgaris subsp, and malva). Laboratory analysis was achieved to measure the ratio of heavy element contamination (Pb, Fe, Ni, Cd, Zn and Cr) using flame atomic absorption spectrophotometer during the summer months of July and August for the year 2017. The study showed that the elements of zinc, chromium, nickel and cadmium were high concentrations and exceeded. The maximum concentration of these
... Show MoreMultimedia is one of the most important elements of modern educational media and must be used in educational websites in order to disseminate knowledge on a large scale and should be used to provide scientific information to all, as the current research tried to explore the possibilities of employing them in the design of educational websites and highlight their role in promoting the scientific aspects of the user. This study included four axes, the first of which was devoted to the introduction which includes the problem of research, its importance, objectives and its objective, temporal and spatial limitations, which were limited to the study of the main pages of Arabic educational websites published in 2019. The second axis contained th
... Show MoreThe rubber ropes exercises affected muscle groups, which in turn affects the corners of the conditions of the body before and over the barrier where affected the time passed. To change the angle of the approaching and payment impact on passing each times the barrier 1-5. That passed over the barrier 1and gate 5 impacts on the nature of the achievement, where time has become less. Find the values of cruise missiles and other phases and stages of pitch angle other categories which it enshrines stood as compelling rejection men's 110m hurdles. Find the value of the instant messaging distances between different barriers and stages. Studies by adding rubber sling barriers race categories, measurement of kinematic variables. Emphasis on the devel
... Show MoreThe current study aims to develop a proposed educational program based on augmented reality (AR) technology, in addition to assessing its effectiveness in developing research and historical imagination skills of the Humanities Track's female students at the secondary stage, as well as assessing the correlative and predictive relationships between the amount of growth for the two dependent variables. To achieve this, a secondary school in the city of Makkah Al-Mukarramah was chosen, and an available random sample of (30) female students from the study population was selected. The quasi-experimental approach was followed by this study, particularly one group design. In addition, two tools were used to collect study data, namely: a test of
... Show MoreThe aim of the research is to identify the international accounting standards and accounting standards for Islamic banks, and to analyze the most important problems in the application of Islamic accounting standards, as well as to analyze some of the principles and methods used in the application of accounting standards in Islamic banks. The research was built on three hypotheses, the first being (there is a tangible impact on the application of international accounting standards for banks’ management of liquidity, achieving profits, maintaining property rights and fulfilling their obligations), and the second (the bank facing obstacles using Islamic accounting standards, as it is expected that when using Islamic accounting standar
... Show MoreThe research aimed at identifying the relationship between motivation and self–confidence on the performing routines in the parallel bar. The researchers used the descriptive method on (480) thirds year college of physical education and sport sciences/ university of Baghdad students. The data was collected and treated using proper statistical operations to conclude that there is a high correlation relationship between motivation and self-confidence with routine performance on parallel bars. In addition to that, the researchers concluded that third-year students have high motivation and self – confidence and there is a positive relationship between motivation, self-confidence, and routine performance on parallel bars.