University of Gonabad

Gonābād, Iran

University of Gonabad

Gonābād, Iran
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Pourhoseini S.H.,University of Gonabad | Naghizadeh N.,University of Gonabad
Journal of the Taiwan Institute of Chemical Engineers | Year: 2017

The present work investigates the effects of different concentrations of silver-water microfluid on the thermophysical properties, Brownian motion and heat transfer performance of a plate heat exchanger. For this purpose, an experimental system which included a CR14-45 COMER plate heat exchanger, five pt100 platinum resistance temperature sensors with temperature control system, two rotameters for flow rate indication and control, an insulated reservoir tank with two immersed heaters in it and a stainless steel centrifugal pump for circulating fluid was prepared. In the next step, silver microparticles were synthesized from AgNO3 and then 8L of silver-water microfluid was prepared with different concentrations in the range of 0-0.125wt% and their thermal conductivity, heat capacity and temperature difference rate were experimentally gauged. The results indicated that all the concentrations of silver-water microfluid (in the range of 0-0.125wt%) enhance thermal conductivity and heat transfer rate in comparison with base fluid (pure water). However, there is an optimum concentration for microfluid (0.03wt%) in which the rate of heat transfer reaches its maximum value. In this case, the heat transfer rate of microfluid is 9% higher than the base fluid. At high microparticles concentrations, due to coagulation effect, some of the silver particles quickly stick together and build deposits on the surface of the plate heat exchanger. Consequently, the concentration of the particles in the microfluid decreases and the enhancement of thermal conductivity (1.25% for 0.125wt%) lowers in comparison with the optimum state. Furthermore, at concentrations beyond the optimum, the slope of temperature difference rate in microfluid is negative and, therefore, the Brownian motion and particles movement diminish and the silver particles tend to sediment. Microparticles deposited on the plate heat exchanger surface contribute to additional heat transfer resistance and decrease the heat transfer coefficients in comparison with the optimum state. © 2017 Taiwan Institute of Chemical Engineers.

Karimian A.,University of Gonabad | Karimian H.,University of Tehran
Journal of Chemical Research | Year: 2017

Several derivatives of the novel 4-(4-methyl-5H-pyrimido[4,5-b][1,4]thiazin-2-yl)morpholine and 4-methyl-2-(piperidin-1-yl)-5H-pyrimido[4,5-b][1,4]thiazine ring systems have been synthesised through cyclocondensation of 5-amino-6-methylpyrimidine-4-thiols and the appropriate α-haloketone in glacial acetic acid under reflux.

A novel, simple and feasible method was proposed for increasing intermediate soot concentration and enhancing thermal and radiative characteristics of natural gas flame. In the method, based on pyrolysis technique, a portion of natural gas, as the secondary gas injection rate, was directly injected into the flame to create high temperature and emissive intermediate soot particles. The portion of the fuel dedicated to secondary injection rate varied in the range of 20–55%. The flame structure, axial temperature, soot concentration and radiation flux were examined and compared with those resulted from a prevalent burner. Also, the optical properties of intermediate soot particles were studied by BOMEM FTIR, IR flame photography and TES-1332A digital luminance meter. The results indicated that natural gas molecules injected into the flame were dominantly pyrolyzed into soot particles. These highly luminous emissive particles enhance the total flame emissivity and radiation. Moreover, considering exhaust emission limits, there was an optimum secondary injection rate (40%), which, besides enhancing the radiation of flame, maintained the emission of CO pollutant and UHC lower than the standard values. Furthermore, in the pyrolysis process absorption of heat from flame reduces maximum flame temperature and consequently NOx emission by 35% in the optimum case. © 2017 Elsevier Ltd

Pourhoseini S.H.,University of Gonabad | Asadi R.,University of Gonabad
Journal of Natural Gas Science and Engineering | Year: 2017

Natural gas, as the cleanest fossil fuel, has been widely applied in central heating systems and industrial burners. From the perspective of energy saving, abundant sources and enormous use of natural gas together with the high costs caused by the widespread use of this fuel make the investigation of natural gas combustion characteristics important. Consequently, in the present work, the thermal and radiative characteristics, and NOx pollutant emission, of a 100,000 kcal/h natural gas burner, widely used in building heating systems, were investigated in the equivalence ratios of 0.42, 0.62, and 0.72. Non-destructive measurements including chemiluminescence method and IR photography were used to investigate the flame characteristics. The results indicated that increasing the equivalence ratio (in the range of 0.42–0.72) moved the peak of flame temperature from flame up-stream to its down-stream and made the flame temperature distribution more uniform. Also it was found that whereas the maximum temperature of flame occurred in small equivalence ratios such as 0.42, the average temperature of flame was 7.8% greater and the average radiation heat flux was 62% greater in large equivalence ratios such as 0.72. The results also showed that increase in equivalence ratio up to 0.72 raised the rate of soot particles generation in the flame and enhanced the average luminosity and radiation of flame in near IR wavelengths and increased the average emissivity coefficient of flame as much as 20%. Moreover, in flame upstream region, the enhancement of radiation heat transfer by increasing equivalence ratio is dominantly as a result of increase in emissivity coefficient of flame, while in flame downstream region, increasing the flame temperature due to gradual combustion will be important in improvement of radiation heat flux. © 2017 Elsevier B.V.

Pourhoseini S.H.,University of Gonabad | Moghiman M.,Ferdowsi University of Mashhad
Journal of Enhanced Heat Transfer | Year: 2014

Natural gas, as a major source of clean energy, has low thermal radiation. Because radiation transfers a considerable portion of heat generated by flame, improving the radiation characteristics of flame is necessary. The aim of this study was to investigate how the injection of small quantities of micro kerosene droplets into a natural-gas flame helps enhance the flame's thermal radiation and consequently its thermal efficiency. For this purpose, a micronozzle injected kerosene droplets into a natural-gas nonluminous flame. Using an IR filter, a digital camera, an S-type thermocouple, a calibrated thermopile, and image processing software, along with numerical modeling, the radiation properties of a flame were studied. The results show that the injection of kerosene droplets causes an increase of 52% and 11.75% in thermal radiation and efficiency, respectively. Also, mean flame temperature increases by no more than 8% whereas the mean flame emissivity coefficient increases remarkably. © 2014 by Begell House, Inc.

Mohammadzadeh Kakhki R.,University of Gonabad
Arabian Journal of Chemistry | Year: 2014

The unique properties of carbon fiber electrodes (CFEs) offer a number of particular advantages for their use in analytical applications. However, some pretreatment is usually necessary for the modification of the carbon surface. One of these methods is enzyme modification, that enzyme reactions in the surface of the electrode can be useful for the certain determinations. Also application of nanoparticles is very useful for modification and gives very interesting responses for the electrode in the determination of various analytes. Electrochemical oxidation of a carbon surface is one of the other methods for modification. With this work the morphology of the surface changes as well as increasing the coverage by various oxygen-containing functional groups. These groups can then interact and bind with other species introduced to the surface. The modification of the surface of carbon fiber electrodes is an interesting topic with many applications in the fields of analytical chemistry, environmental and health science, fuel cell and biofuel cell and many others. In this review article we discussed about the various modification methods for carbon fiber electrodes and applications of these CFEs. © 2014 The Author.

Kakhki R.M.,University of Gonabad
Russian Journal of Applied Chemistry | Year: 2016

The surface structure of common graphite electrodes are suitable for electrochemical detection of various analytes due to their favorable properties such as good conductivity and resistance to environmental and chemical hazards. Also this material is cheap and available. Modifying the surface of electrode improves their ability for various determinations. Modifying graphite electrodes with nanoparticles has attracted lots of attention due to their unique characteristics. In this article we review applications of modified graphite electrodes with nanomaterials. © 2016, Pleiades Publishing, Ltd.

Mohammadzadeh Kakhki R.,University of Gonabad
Journal of Inclusion Phenomena and Macrocyclic Chemistry | Year: 2015

Compared to the traditional micron-sized supports used in separation process, nano-sized adsorbents possess quite good performance due to high specific surface area and the absence of internal diffusion resistance, which improve adsorption capacity. Recently, magnetic technology has been applied in pollution removal. Over the past few years, magnetic adsorption technology has attracted considerable attention for use in dye and metal removal. Magnetic nanoparticles are particularly attractive because of their inherent properties such as large surface area and fast response under applied external magnetic field. The high surface area to volume ratio and superparamagnetism of magnetic nanoparticles, combined with formation of complexes between adsorbent and β-cyclodextrins (β-CD), can effectively remove pollutants from wastewater. These nanoparticles modified with cyclodextrins also can be used in chiral separations. Therefore nowadays, efforts are being made to magnetic nanoparticle modified with CDs as efficient adsorbent in separations. © Springer Science+Business Media Dordrecht 2015.

Shahi H.,University of Gonabad | Ghavami R.,University of Shahrood | Rouhani A.K.,University of Shahrood
Journal of Geochemical Exploration | Year: 2016

The surface geochemical data in spatial domain can be transferred to frequency domain using two-dimensional Fourier transformation. The analysis of surface geochemical data in frequency domain has been led to the exploratory information which may be not achievable in the spatial domain of geochemical data. In this research, the frequency domain of surface geochemical data has been analyzed for recognizing the complex geochemical patterns related to ore deposits. In order to predict the variations of mineralization in the depth and identifying the blind mineral deposits, the developed Frequency Coefficients Method (FCM) has been proposed and applied in hidden Zafarghand Cu-Mo porphyry deposit. This proposed approach has desirably demonstrated the relationship between different frequencies in the surface geochemical distribution map and various depths of deposits. The results, obtained from applying the proposed technique to a real scenario, reveal significant improvements, compared to the results obtained from the spatial domain of geochemical data. The introduced method as a pattern recognition technique makes possible, without exploration drilling, the determination of mineralization trends in depth and the distinction between blind mineralization and dispersed ore mineralization zones. © 2015 Elsevier B.V.

Mohammadzadeh Kakhki R.,University of Gonabad | Rakhshanipour M.,University of Zabol
Arabian Journal of Chemistry | Year: 2015

There is a general need to develop simple, rapid, and inexpensive detection assays for diagnostic applications and environmental analysis. Currently, most analyses are performed under laboratory conditions, frequently with the assistance of expensive instruments and trained personnel. Colorimetric sensors as dipsticks or in a chromatographic format would be ideal for the various analyses. These sensors need minimal instrumentation and achieve high sensitivity. In recent years, metallic nanoparticles especially gold nanoparticles and silver nanoparticles have been widely used as colorimetric probes for chemical sensing and biosensing. This interesting application is due to their unique size-dependent, interparticle distance dependent, absorption spectra and solution color. When the nanoparticles approach each other and aggregate, the color of the nanoparticles changes from red to purple (or blue) for gold nanoparticles and from yellow to red (or dark green) for silver nanoparticles respectively. This phenomenon is due to the shift of the surface plasmon band to longer wavelength. Crown ethers are known for the unusual property of forming stable complexes with cations. The oxygen atoms lie in a nearly planar arrangement about the central cation. Today the development of crown ether functional nanoparticle as colorimetric sensors is a subject of considerable interest. In this article we investigated on the use of nanoparticle modified with crown ether for sensing of metal ions and also charged molecules with colorimetric technique. © 2015 The Authors.

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