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In tube Condensation:Changing the Pressure Drop into a temperature Difference for a Wire-on-tube Heat Exchanger

Fluid Dynamics & Materials Processing 2023年第9期19卷 2201-2214页

作者： Louay Abd Al-Azez Mahdi Mohammed A.Fayad miqdam t.chaichan Energy and Renewable Energies technology Center University of Technology-IraqBaghdad65035Iraq

A theoretical study based on the Penalty factor(PF)method by Cavallini et al.is conducted to show that the pressure drop occurring in a wire-on-tube heat exchanger can be converted into a temperature difference for two types of refrigerants R-134a and R-600a typically used for charging refrigerators and freezers.the following conditions are considered:stratiﬁed or stratiﬁed-wavyﬂow condensation occurring inside the smooth tube of a wire-on-tube condenser with diameter 3.25,4.83,and 6.299 mm,condensation temperatures 35℃,45℃,and 54.4℃ and cover refrigerant massﬂow rate spanning the interval from 1 to 7 kg/hr.the results show that the PF variation is not linear with vapor quality and attains a maximum when the vapor quality is 0.2 and 0.18 for the R-134a and R-600a refrigerants,respectively.the PF increases with the refrigerant massﬂow rate if the inner diameter and saturation temperature constant,and it decreases on increasing the inner diameter to 6.299 mm for constant refrigerant massﬂow rate and saturation temperature.the PF for R-600a is higher than that for R-134a due to the lower saturation pressure in theﬁrst case.Furthermore,a stratiﬁedﬂow produces higher PF in comparison to the annularﬂow due to the effect of the surface tension.

关键词： Condensation penalty factor pressure drop temperature difference two-phase wire condenser

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Effect of Al_(2)O_(3) Nanoparticles on the Compression Ignition Performances and Emitted Pollutants of a Diesel Engine

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Fluid Dynamics & Materials Processing 2023年第11期19卷 2847-2861页

作者： Noora S.Ekab Ahmed Q.Salam Ali O.Abd miqdam t.chaichan Electromechanical Engineering Department University of Technology-IraqBaghdad65035Iraq Environment Research Center University of Technology-IraqBaghdad65035Iraq Applied Science Department University of Technology-IraqBaghdad65035Iraq Energy and Renewable Energies technology Center University of Technology-IraqBaghdad65035Iraq

to improve the performances of diesel engines and to reduce the pollutants they emit,aluminum oxide nanopar-ticles in varying quantities(50,100,150 ppm)have been added to conventional diesel fuel.the results of such experimental tests have revealed that the addition of nano-Al_(2)O_(3) particles to the diesel fuel reduces its consump-tion by 0.488%,1.02%,and 1.377%,respectively and increases the brake thermal efficiency by 1.4%,2.6%,and 3.8%,respectively.the concentrations of undesired gases decrease accordingly by 1.5%,1.7%,and 2.8%for HC and by 5.88%,11.7%,and 17.6%,respectively,for CO.For the same percentages of nanoparticles,NO_(x) increases by 2.65,4.36,and 5.37,while the tSP(total Suspended Particulate)decreases by 22%,34.66%,and 49.7%,respectively.In the same conditions,sulfur dioxide pollutants increase by 4.57%,8.8%and 12.89%,and H_(2)S levels by 4.7%,7.81%and 8.9%,respectively.

关键词： Nao-Al_(2)O_(3) suspension CO NO_(x)-PM trade-off SO_(2) H_(2)

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A Reliability Impact and Assessment of Distributed Generation Integration to Distribution System

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Energy and Power Engineering 2013年第4期5卷 1043-1047页

作者： Atthapol Ngaopitakkul chaichan Pothisarn Sulee Bunjongjit Boonlert Suechoey Chaiyo thammart Auttarat Nawikavatan Department of Electrical Engineering Faculty of Engineering King Mongkut’s Institute of Technology Ladkrabang Bangkok Thailand Department of Electrical Engineering Faculty of Engineering South-East Asia University Bangkok Thailand

the main purpose of this paper is to study the reliability due to the employment of distributed generations (DG) integrated to distribution system. the system under this study is from Provincial Electricity Authority (PEA) that is a part of thailand’s distribution system. Data of geographic information systems (GIS) including the distance of distribution line and location of load that are parameter of PEA is simulated using digital simulation and electrical network calculation program (DIgSILENt) to analyze the impact of reliability with the installing DG into the distribution system. the system average interruption frequency index (SAIFI), the system average interruption duration index (SAIDI) and interruption cost are assessed as index of reliability by comparing the SAIFI, SAIDI, and interruption cost between the base case (no DG) and the case that DG connected to the distribution system. the results can be summarized by focusing on location of DG, the capacity of DG, the size of load, and the distance of load which are factors able to impact to SAIFI, SAIDI, and interruption cost.

关键词： Reliability Distributed Generation Interruption Cost Distribution System SAIFI SAIDI

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Study of Coordination between Protective Devices Comprising Distributed Generation in Distribution System

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Energy and Power Engineering 2013年第4期5卷 584-588页

作者： Sujarit Muangchareon Atthapol Ngaopitakkul Sulee Bunjongjit Monthon Leelajindakrairerk chaichan Pothisarn Auttarat Nawikavatan Department of Electrical Engineering Faculty of Engineering King Mongkut’s Institute of Technology Ladkrabang Bangkok Thailand Department of Electrical Engineering Faculty of Engineering South-East Asia University Bangkok Thailand

this paper proposes to study the coordination of protective devices when 8 MW synchronous generators are interconnected to distribution System of PEA. the coordination between recloser and drop out fuse is investigated in this paper. the three-phase fault is simulated using digital simulation and electrical network calculation program (DIgSILENt). the results are shown that the short circuit current from substation is reduced comparing to the distribution system without DG connected. It causes to protective device coordination inconsistently, so the maintenance will be delayed more than expected.

关键词： Coordination Distributed Generation Protective device Renewable Energy

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