The electrical and thermal performance of a typical single pass hybrid photovoltaic/thermal (PV/T) air collector is modeled, simulated and analyzed for two selected case studies in Iraq. An improved mathematical thermo-electrical model is derived in terms of design, operating and climatic parameters of the hybrid solar collector to evaluate its important characteristics: collector flow and heat removal factors, PV maximum power point and its temperature coefficient, and overall power and efficiency. Unlike previous PV/T thermal models, the present model is obtained with some additions and corrections in radiation and convection heat coefficients for the top loss and for the air duct with more applicable sky temperature correlation. The well-known 5-parameter electrical model of PV module is solved using improved boundary conditions and translation equations for better convergence and accuracy. The voltage temperature coefficient of the PV module is included in the boundary conditions for convergence stability. The module parameters are taken to be dependent on solar radiation and PV cell temperature for improved accuracy. A Matlab computer simulation program is developed to solve the thermo-electrical model. The developed model is verified with previously published experimental results and theoretical simulations; it is proved to be most accurate in respect to percentage errors and correlation coefficients. Different parameters of the PV/T collector such as cell and air temperatures, thermal gain, PV current and voltage, and fill factor have been investigated. The results identified the effects of most important operating conditions such as sky, inlet and cell temperatures, air flow rate and incident solar radiation on the performance of the hybrid collector. The approved model is applied for a winter day (22 January 2011) in Baghdad city and for a summer day (20 May 2011) in Fallujah city. It is found that the electrical, thermal and overall collector efficiencies for the two case studies were 12.3%, 19.4% and 53.6% respectively for the winter day, while that for the summer day were 9%, 22.8% and 47.8%.
Continuous escalation of the cost of generating energy is preceded by the fact of scary depletion of the energy reserve of the fossil fuels and pollution of the environment as developed and developing countries burn these fuels. To meet the challenge of the impending energy crisis, renewable energy has been growing rapidly in the last decade. Among the renewable energy sources, solar energy is the most extensively available energy, has the least effect on the environment, and is very efficient in terms of energy conversion. Thus, solar energy has become one of the preferred sources of renewable energy. Flat-plate solar collectors are one of the extensively-used and well-known types of solar collectors. However, the effectiveness of the coll
... Show MoreIn the present work, the focusing was on the study of the x-ray diffraction, dielectric constant, loses dielectric coefficient, tangent angle, alter- natively conductivity and morphology of PET/BaTio3. The PET/BaTio3 composite was prepared for polyethylene terephthalate PET polymer composite containing 0, 10, 20, 30, 40, 50, and 60 wt. % from Barium titanate BaTi03 powder. The composite of two materials leads to form mixing solution and hot-pressing method. The effect of BaTio3 on the structure and dielectric properties with morphology was studied on PET matrix polymer using XRD, LCR meter and SEM.
: zonal are included in phraseological units, form metaphorical names for a person, give him various emotional and evaluative characteristics. This article examines the topic of zoomorphic metaphors that characterize a person in the Russian and Arabic languages in the aspect of their comparative analysis, since the comparative analysis of the metaphorical meanings of animalisms is an important method for studying cultural linguistics, since zoomorphic metaphors are a reflection of culture in a language.
Despite their potential as a sustainable energy technology, the operation of proton exchange membrane fuel cells (PEMFCs) in sub-freezing conditions remains a critical challenge due to the risk of ice formation and performance degradation. This study introduces a new passive thermal management technique using strategically arranged multi-layer phase change materials (PCMs) to address this challenge. A numerical model was developed to evaluate the thermal behavior across various PCM configurations, incorporating one, two, and three layers arranged both in parallel and series with distinct melting points ranging from 55 to 65 ◦C. The results show that multi-layer PCM configurations provide significant improvements over the single-layer base
... Show MoreCitrus fruits are one of the consumer agricultural products of the Iraqi citizen. It is rich in vitamins and usedin many food industries as well as medicines. Classifying the amount of production of citrus treesaccording to the producing governorates has been done to find a map that shows the production of citrustrees according to Iraqi governorates. A cluster analysis method was used according to the hierarchicalmethod. The results showed that Najaf and Qadisiyah are the most similar in citrus production, whileSaladin and Najaf were the two governorates with the furthest distance in proximity matrix. Diyalagovernorate was clustered in the first cluster within two, three, four or five of the clusters for classifyingIraqi governorates covere
... Show MoreRegulatory T (Treg) cells are one of the major immunosuppressive cell types in cancer and a potential target for immunotherapy, but targeting tumor-infiltrating (TI) Treg cells has been challenging. Here, using single-cell RNA sequencing of immune cells from renal clear cell carcinoma (ccRCC) patients, we identify two distinct transcriptional fates for TI Treg cells, Fate-1 and Fate-2. The Fate-1 signature is associated with a poorer prognosis in ccRCC and several other solid cancers. CD177, a cell surface protein normally expressed on neutrophil, is specifically expressed on Fate-1 TI Treg cells in several solid cancer types, but not on other TI or peripheral Treg cells. Mechanistically, blocking CD
Land Use / Land Cover (LULC) classification is considered one of the basic tasks that decision makers and map makers rely on to evaluate the infrastructure, using different types of satellite data, despite the large spectral difference or overlap in the spectra in the same land cover in addition to the problem of aberration and the degree of inclination of the images that may be negatively affect rating performance. The main objective of this study is to develop a working method for classifying the land cover using high-resolution satellite images using object based method. Maximum likelihood pixel based supervised as well as object approaches were examined on QuickBird satellite image in Karbala, Iraq. This study illustrated that
... Show MoreThe oil sector in Iraq suffered from several difficulties led to the decline and reduction of oil production and the deterioration of refineries and transport pipeline status in addition to the weakness of the technology side and the prevalence of financial and administrative corruption besides the high costs of rehabilitation of the oil sector and also administrative and institutional problems still ongoing.
In spite of Iraq's possession of vast oil wealth allows him to play an important role in the international energy market، he is still under the level. The production of oil doesn'<
... Show MoreIn this work Study effect of annealing temperature on the Structure
of a-Se and electrical properties of a-Se/c-Si hetrojunction have been
studied.The hetrojunction fabricated by deposition of a-Se film on c-
Si using thermal evaporation.
Electrical properties of a-Se/ c-Si heterojunction include I-V
characteristics, in dark at different annealing temperature and C-V
characteristics are considered in the present work.
C-V characteristics suggested that the fabricated diode was
abrupt type, built in potential determined by extrapolation from
1/C2-V curve. The built - in potential (Vbi) for the Se/ Si System
was found to be increase from 1.21 to 1.62eV with increasing of
annealing temperature