Optimization of baffle spacingon heat transfer, pressure drop and estimated price in a shell-and-tube heat exchanger

In this paper for a given heat duty, study of the effects of baffle spacing on three parameters mentioned above is considered in a STHX with single segmental baffles and staggered tubes layout in Iran, Arvand petrochemical. A program in EES (Engineering Equations Solver) software is used for this purpose to solve governing equations; moreover, Aspen B-JAC and HTFS+softwares are used for considering estimated total price. At first the simulated results obtained from this program is compared to the experimental data for two cases of baffle spacing. The effects of baffle spacing are considered from 4 to 24 inches over overall heat transfer coefficient (OHTC) to pressure drop ratio (U/Δp ratio). The results show that U/Δp ratio is low when baffle spacing is minimum (4 inches) because pressure drop is high; however, heat transfer coefficient is very significant. And in this case estimated total price increases 7 percent. Then with the increase of baffle spacing, pressure drop rapidly decreases and OHTC also decreases, but the decrease of OHTC is lower than pressure drop, so (U/Δp) ratio increases. After increasing baffles more than 12 inches, variation in pressure drop is gradual and approximately constant and OHTC decreases; Consequently, U/Δp ratio decreases again. If baffle spacing reaches to 24 inches, STHX will have minimum pressure drop, but OHTC decreases, so required heat transfer surface increases and U/?p ratio decreases. After baffle spacing more than 12 inches, variation of both estimated price and shell side pressure drop is negligible. So optimum baffle spacing is suggested between 8 to 12 inches (43 to 63 percent of inside shell diameter) for a sufficient heat duty, low cost and low pressure drop. © IDOSI Publications, 2012

Using HPM for approximating the instability of narrow bio-sensor used in bio-electronic, biology and cancer detection

Recently biosensors become one of the most components in evaluating live systems and medical applications. These applications are detection of cancers, DNA, tumors, cells, bio-enzymes etc. In this paper, we investigate the instability of narrow bio nano electro mechanical system (bio-NEMS) sensor. The proposed HPM is employed to solve nonlinear constitutive equation of cantilever beam-type bio-sensor. An analytical solution is obtained in terms of convergent series with easily computable components. The basic design parameters such as critical cantilever tip deflection of the bio-sensor are comp uted. The analytical results agree well with numerical solutions and those from the literature. © IDOSI Publications, 2012

Study the sources of mercury vapor in atmosphere as a threatening factor for human health and bio-filtering methods for removal of toxic pollution

A global atmospheric transport model is used to calculate mercury concentrations in the atmosphere. In this study, a comprehensive analysis was made to describe the environmental behavior and pollution status of mercury (Hg). The most important aim in this study is to show mercury pollution sources and to introduce some new technologies for removing this dangerous material from air. In this paper, some bio technologies such as bio filtering method and bio adsorbent such as leaves of trees was introduced. The capacity and application of biotrickling filters for the removal of mercury vapor from simulated flue gases was expressed. It was resulted from paper that the most prominent source of mercury is the east of Asia and the southeast of Asia. The lowest source is concerned Australia. In this investigation it was found that activated carbon can be one of the best tools for removal of mercury vapor. The adsorbent uniquely combines a chelating ligand with an ionizing surface nano-layer on a mesoporous substrate was the other consequences of this study which can be as a suitable adsorbent for omitting this pollutant from atmosphere

Simulating The Cooling Of Medical Ct-Scanners: Part 1: Formulation

CT-scanners are used as an non-invasive detecting method in medical applications as a powerful radiological device. Many patients are used CT-scanners for detecting disease. However CT-scanners required cooling due to the huge heat generated during the operation. In this work we modeled a convection-diffusion cooling process of CT-scan devices. A flow in a rectangular body with symmetry, constant heat flux and constant temperature boundary conditions has been considered. The governing equation has been discredited based on the finite volume method and has been solved using a fully implicit method. This paper is mostly concerned with the problem description and the results presents in part 2 of this paper. Hafshejani M K, Dadjoo F, Alimoradi F, Falavand A, Arad A. Simulating the Cooling of Medical CT-Scanners: Part 1: Formulation. Life Sci J 2012;9(1):1029-1034] (ISSN:1097-8135). http://www.lifesciencesite.com. 14

Study of the health threatening mercury effective parameters for its removal from the aqueous solutions by using activated carbons

A serious environmental threat from heavy metal ion pollution, especially mercury, has generated a great deal of attention in recent years. Mercury is one of the priority pollutant listed by USEPA as it can easily pass the blood-brain barrier and affect the fetal brain. High concentration of Hg (II) causes impairment of pulmonary function and kidney, chest pain and dyspnoea. Consequently, removal of mercury in water and wastewater assumes importance. In this review paper, we have evaluated the efforts which have been done for controlling the mercury emissions from aqueous solutions. According to the EPA agency, the tolerance limit for Hg (II) for discharge into inland surface water is 10 mu g/l and for drinking water is 1 mu g/l. Mercury (Hg) is one of the heavy metals of concern and has been found in the waste waters coming from manufacturing industry, and natural sources. Among several types of technology for removing of Hg in water (chemical precipitation, reverse osmosis, ion-exchange, etc.), adsorption is one of most frequently used. It is a complex process involving physical, chemical, and electrical interactions at sorbent surfaces. Therefore, in this study will investigate effective parameters such as pH, initial concentration and surface characteristic. Hafshejani MK, Khandani F, Heidarpour R, Sedighpour A, Fuladvand H, Shokuhifard R, Arad A. Study of the health threatening mercury effective parameters for its removal from the aqueous solutions by using activated carbons. Life Sci J 2012;9(4):1789-1791] (ISSN:1097-8135). http://www.lifesciencesite.com. 27

Study of the mercury removal for health care and the effect of PH in mercury removal from aqueous solutions by activated carbons

A serious environmental threat from heavy metal ion pollution, especially mercury, has generated a great deal of attention in recent years. Mercury is one of the priority pollutant listed by USEPA as it can easily pass the blood-brain barrier and affect the fetal brain. High concentration of Hg (II) causes impairment of pulmonary function and kidney, chest pain and dyspnoea. Consequently, removal of mercury in water and wastewater assumes importance. In this review paper, we have evaluated the efforts which have been done for controlling the mercury emissions from aqueous solutions. According to the EPA agency, the tolerance limit for Hg (II) for discharge into inland surface water is 10 mu g/l and for drinking water is 1 mu g/l. Mercury (Hg) is one of the heavy metals of concern and has been found in the waste waters coming from manufacturing industry, and natural sources. Among several types of technology for removing of Hg in water (chemical precipitation, reverse osmosis, ion-exchange, etc.), adsorption is one of most frequently used. It is a complex process involving physical, chemical, and electrical interactions at sorbent surfaces. Therefore, in this study will investigate effective parameters such as pH, initial concentration and surface characteristic. Hafshejani MK, Vahdati A, Vahdati M, Kheradmand AB, Sattari M, Arad A. Study of the mercury removal for health care and the effect of PH in mercury removal from aqueous solutions by activated carbons. Life Sci J 2012;9(4):1846-1848] (ISSN:1097-8135). http://www.lifesciencesite.com. 28

Comparison between Homotopy Perturbation and Modified Adomian Decomposition Methods in Simulating the Effect of Van der Waals Attraction in Nano Structures Instability

Abstract: In recent years, the instability of nano scale structures has become of great interest for scientists. In this work the ability of Homotopy perturbation and modified Adomian decomposition methods for modeling the effect of Van der Waals attraction in the nonlinear instability of cantilever and doublysupported Carbon Nano Tubes (CNT) based bio sensor and nano bio sensor is comparatively investigated. The critical value system deflection at the onset of the instability is computed as the basic parameter for sensor applications. It is found that using Homotopy perturbation method (HPM) in solving nano structures problems can lead to physically incorrect results. The values of the instability parameters computed by HPM series converge to the values which originally differ from those obtained by numerical methods. Even more, in the case of doubly-supported CNT or nano sensor, the conventional series diverge from numerical solution as the number of series terms increases. These shortcomings are not observed for modified Adomian series. Key words: Bio sensor • nonlinear differential equation • homotopy perturbation • modified adomian decomposition • instabilit

Impact of solar energy application on warming, health caring and pollution prevention in Iran

Abstract: Solar energy is cited as a clean alternative to fossil fuels. Solar panels generate energy without producing ambient pollution. Therefore, there is no argument that pure solar energy is a clean, green energy source. The result in the present paper shows that by using renewable energy special sun light energy, considerable amounts of Greenhouse polluting gasses are avoided. The use of conventional energy in factories and vehicles in has been a major source of pollution health hazards. These hazardous pollutants, such as suspended particle, heavy metal, organic matter and carbon monoxide (CO) adversely affect health. Although solar energy has significant environmental benefits in comparison to the fossil fuel, some problems has be seen in this way. The important advantage is related to the reduced CO2 emission and air pollution prevention and it can be said this method for producing energy which has some economic benefit. The supplies of the fossil fuels used to generate much of its shrink, the cost of this energy is increasing worldwide. Solar energy allows human to generate its own energy in cheap way. To the best of our knowledge, the comparison of two categories of energy and investigation in the benefits of solar energy as a new way in Iran are investigated to prevent our environmental and natural sources