seyfolah saedodin

In this research, an integrated fossil-solar energy system has been designed, modeled, and optimized to supply the required loads of a six-story educational building in Tehran. The three heating, cooling, and electrical loads of the building are extracted in an hourly dynamic pattern for one year. System modeling was performed using a developed code in MATLAB software, and the genetic algorithm was used for two and three objective optimizations. The results show that with the two objectives of exergy efficiency and pollution, 68 rows of PVT panels and a solar collector with an area of ​​6.25m2 should be used. In this case, the maximum use of solar energy to supply 1945.9MWh heat and 484.5MWh electricity occurred during a year. Also, the highest amount of purchased electricity from the grid is 501.9MWh when the exergy efficiency and cost rate are considered as objective functions. In the three-objective optimization, the best system has an exergy efficiency of 50.21%. The CO2 emission and total cost rate are 7.1$/h and 301g/kWh, respectively. In this case, about 583.06 kWh of the heating load is supplied annually by 20 rows of PVT and a solar collector which has an area of 5.27m2. Photovoltaic panels generate 144.1MWh of the system's required electricity. The electricity sold to the grid in this scenario is 55.05MWh. Also, the system has purchased 204.2MWh of electricity from the grid annually. This means that the system should buy electricity from the grid most of the time each year.

The main purpose of this study is to investigate the effect of the pulsating of the inlet jet on the heat transfer rate short distances of the nozzle from the concave surface. For this purpose, three-dimensional simulation of flow and heat transfer of sinusoidal pulsed jets on the concave surface has been performed at distances of 0.5 times of nozzle diameter to 4 and for Reynolds numbers of 7000 and 14000. The results of the numerical simulation are in good agreement with the experimental results of the steady jet. The result shows that the effect of pulsating the flow with the sine function decreases at short distances between the jet and the concave surface. So that at a distance of 4 times of nozzle diameter, pulsating jet led to a 10% increase in the average Nu, while this value is equal to 5% for a distance of 0.5 times of nozzle diameter. It can be found that pulsating the flow decreases Nu at low frequencies, and then with increasing the frequency of the pulsed jet, the Nu number increases. Furthermore, with increasing the distance between the surface and the inlet jet, the Nu number decreases significantly. This rate of reduction is lower in comparison to the steady jet.

Nanotechnology products have created a new industrial revolution that can be effective and useful in different fields including industry, agriculture, pharmacy, medicine, etc. Nanotechnology is a branch of applied knowledge and technology which covers a wide range of matters. The unique feature of nanotechnology is the elements called nanomaterials or nanostructures. In this regards, this paper is presented aimed at evaluating the efficiency of nanotechnology products from technical, economic, ad social perspectives (case study: Nano engine oil). In order to evaluate the technical efficiency of nanotechnology products, several important indicators in this industry including viscosity index, flash point, pour point, density, and the total alkalinity were measured before adding the nanomaterials and after conversion to a product, and the efficiency of the products was evaluated regarding the importance coefficient of each of the indicators. In order to evaluate the economic efficiency of Nano engine oils, the studied indicators were decreased fuel consumption, and decreased air pollution. Testing method in this research is pair wise data comparison regarding the importance coefficient. The research results approve the research hypothesis which suggests the increased efficiency of nano engine oil in the case of using nanotechnology in production process, and by changing the used technologies and moving towards Nano engine oils with a 55-percent increase of the final price of the product, technical efficiency of the Nano engine oils is raised by 46%, and this increased efficiency leads to social and economic efficiency of the product respectively by 30% and 16%.

Considering the serious environmental damages caused by the population growth in human communities and the improper use of natural resources, the environment protection has gained such importance that it is seen as a national and governmental problem. This study aimed to assist environmental peacekeepers in distinguishing eco-friendly companies from non-eco-friendly ones, introducing a comprehensive model and a report consistent with the environmental approach. The research methodology included the input-output analysis and the pair-wise comparison. The results showed the importance of a social value added statement as a report on the environmental and social performance of a business entity. This study showed that the contribution of the social value added to the Green Policy has increased by 38 times.

In this study, the dynamic viscosity of the fluid is water-based nanofluids magnesium oxide discussed. The experiments in four volume fraction (0.005, 0.01, 0.015 and 0.02) and four different diameter nanoparticles 20, 40, 50 and 60 nm were used. The results obtained in this way is that by increasing the volume fraction of a specified diameter, the viscosity of nanofluids increases and by increasing the diameter Nanvdrh in a specified volume fraction, the viscosity of nanofluids decreases the viscosity reduction benefits of using nanofluids in the industry more.

The present study aimed to investigate the convective heat transfer coefficient of nanofluids containing magnesium oxide nanoparticles in water-based fluid in the exchanger plates have been carried out. Tests on the volume fraction of (0.005, 0.01, 0.015and 0.02) were used in this study have Ast.nanvzrh which has a diameter of 20 nm. Also the results show that with increasing fraction nanofluid volume, heat transfer coefficient and thus increases the heat transfer. Also heat transfer nanofluids% increase in volume fraction of 0.02 to 0.005 respectively 52% and 4.3% is on.

Sustainability accounting by presenting a holistic view of the organization activities and providing a balanced view of its economic, social and environmental impacts and benefits, and by presenting sustainability reporting seeks to encourage business units and investors to maintain the mutual benefits of all stakeholders in the society. Given the criticisms that researchers have had about the efficiency of sustainability reporting, the purpose of this article is to develop sustainability accounting by presenting a new model that can address the challenges in sustainability accounting and can be a good alternative to sustainability reporting. Social value-added is the sum of tangible and intangible values created and added to society by a business through technological development/change and the knowledge of its manufacturing engineers and managers. In this research, to test the proposed social value added model, Nano engine oil was selected randomly and the test was performed using paired comparison of data. The results of the research showed that social value-added statement can be an appropriate report for evaluating the economic, social and environmental performance of a business entity. Nano engine oil has a social value added of 3797.2 percent compared to regular engine oil, that 15 percent of it is related to tangible value added and 85 percent to intangible value added.

The evaluation of corporate social responsibility has gained significance over the past decade due to the importance of natural and environmental resources. Many studies have been conducted on corporate social responsibility and the presented related models, which add to the importance of this report. However, in addition to its significance, many researchers also believe that corporate social responsibility evaluation models lack the necessary efficiency due to different interpretations, lack of transparency, and abuse of some companies in order to deceive and commit fraud. Therefore, the aim of this research is to present a model to evaluate corporate social responsibility using value added, which can be a suitable criterion in evaluating the social responsibility of commercial entities. In the present study, first, a model was developed based on corporate social responsibility, and then, to test the model, social value added of Nano motor oil was studied as a case study. In this study, data was analyzed through pairwise comparison. The findings of the study conducted on the social value added of Nano motor-oil indicate economic efficiency of 40%, product social efficiency of 8%, and depicts a 38-times increase in social value added compared with its economic added value. Thus, Nano-engine oil producing companies are located on the corporate social responsible category and the corporate social responsibility in this product is on the third level (strong) that indicates the product’s efficiency in the community and can be a suitable incentive for all business organizations to pay more attention to their products’ environmental and social impacts.

The present paper focuses on problem of mixed convection fluid flow and heat transfer of Al2O3-water nanofluid with temperature and nanoparticles concentration dependent thermal conductivity and effective viscosity inside Lid-driven cavity having a hot rectangular obstacle. The governing equations are discretized using the finite volume method while the SIMPLER algorithm is employed to couple velocity and pressure fields. Using the developed code, the effects of cavity inclination angle, diameter and solid volume fraction of the Al2O3 nanoparticles on the flow and thermal fields and heat transfer inside the cavity are studied. The results show that at all solid volume fraction the average Nusselt number has inverse relationship with nanoparticles diameter. Also the results have clearly indicated that with increasing slope of the cavity to 90 degree, heat transfer continuously decreases at all studied Richardson numbers© 2017 Published by Semnan University Press. All rights reserved.

In the present work, the experimental Study of the radiation and natural convection heat losses from two finite concentric cylinders with radiation shields is investigated. The enclosure consists of two concentric cylinders with hotter inner cylinder and radiation shields with three different materials (aluminum, copper and steel) are inserted between the cylinders at different radial positions. The effects of physical properties (emissivity), geometrical effects of radiation shields, inner cylinder temperature, and enclosure pressure on the heat losses have been investigated. The calculations were performed for two different inner temperatures as 200, and 400ºC, and at two enclosure pressures of 0.2 and 1.0 atm. Results showed that the enclosure pressure and radiation shield emissivity together reduce the total heat loss from the inner cylinder.

Investigation of the radiation and natural convection heat losses from two finite concentric cylinders with radiation shields is performed numerically. The enclosure consists of two concentric cylinders with hotter inner cylinder and radiation shields with three different materials (aluminum, copper and steel) are inserted between the cylinders at different radial positions. The effects of physical properties (material), geometrical effects of radiation shields, inner cylinder temperature, and enclosure pressure on the heat losses have been investigated. The calculations were performed for two different inner temperatures as 473.15, and 673.15 K, and at two enclosure pressures of 0.2 and 1.0 atm. Results showed that the enclosure pressure and radiation shield emissivity together reduce the total heat loss from the inner cylinder.

Forced convection heat transfer in metal foams in the presence of radiation heat transfer is studied using the homotopy perturbation method (HPM). To see wall effects, Darcy-Brinkman model for the flow in porous media is used. A constant heat flux is imposed at the wall and the radiation heat transfer is modeled by a temperature-dependent conductivity. In the present study the case of conjugate convection and radiation heat transfer is analyzed by a semi-analytical approach for the first time. Effects of the radiation parameters (λ, Tr) and porous medium shape parameter (s) on the Nusselt number and dimensionless temperature profile are investigated. Moreover, a discussion on the accuracy and limitations of the HPM method will be presented.

The aim of the present study is to investigate the applications of nanofluids in various industrial and engineering applications. Nanofluids are new types of fluids produced by dispersing Nano-particles in a base fluid. Nowadays, regarding the fact that the applications of nanofluids in thermal systems, motor oils, lubricants and so forth are flourishing and booming day by day, these fluids have been strongly in the spotlight of researchers. In this study, the applications of nanofluids in heat exchangers, chillers, machining, solar water heating, engine cooling, cooling of electronic components, oscillating heat pipe, and cooling nuclear reactors have been investigated. The results showed that nanofluids possess grater thermal conductivity compared with those of conventional fluids.

Rheological characteristics of Al2O3, CuO and TiO2 nano particles were investigated in oil as the base fluid at 1 and 2 wt.%. Constitutive relations for non-Newtonian fluid were discussed based on the power-law model. Measured viscosities of each nanofluid were used to evaluate the power-law and consistency index. Results indicated that the nanofluid viscosity decreased by increasing the concentration. Oil showed shear thickening behavior while nanofluids showed shear thinning behavior. An increase in nano-particle concentration caused a decrease in the power-law index beside an increase in the consistency index. Moreover, the present study showed that the effective viscosity of fluids would be decreased by nanoparticle addition at some wt.% and some shear rates. Furthermore, results showed that the classic models for nanofluid viscosity couldn’t predict their real values of nano fluid viscosity, as the measured values are less than the predicted ones.

Experimental study of effective thermal conductivity of ZnO/EG nanofluid is presented in this research. The nanofluid was prepared by dispersing Zno nanoparticles in ethylene glycol using a sonicator and adding surfactant. Ethylene glycol based nanofluid containing ZnO nanoparticle with a nominal diameter of 18 nm at different solid volume fractions (very low to high) at various temperatures was examined for the investigation. The thermal conductivity of nanofluids is experimentally measured with THW method and it is found that the thermal conductivity of nanofluids increase with the nanoparticle volume concentration and temperature. Also, based on experimental values of thermal conductivity of nanofluid, three experimental models are proposed to predict thermal conductivity of nanofluids. The proposed models show reasonably excellent agreement with our experimental results.

The aim of the present study is to investigate the effects of shear rate on dynamic viscosity of MWCNT-ZnO/engine oil hybrid nanofluid. Using two-step method and without using any surfactant, the studied nanofluid has been produced in different solid concentration (0.125, 0.5, and 1%) as the experimental sample. All the experiments were conducted in the temperatures ranging from 5 to 55°C and shear rates ranging from 50 to 1000 RPM. Based on the experimental results, although the base fluid showed Newtonian behavior in all the studied temperatures and shear rates, in the temperatures of 5 and 15°C, the studied nanofluid shows Non-Newtonian behavior while it shows Newtonian behavior in the temperatures of 25, 35, 45, and 55°C.

Whereas in electrical discharge machining (EDM) the heat flux entering the workpiece is extremely high, the Fourier heat conduction model may fails. This article reports on determination of temperature distribution in the workpiece due to EDM using non-Fourier heat conduction model. Equations are solved by deriving the numerical solution. The temperature layers and profiles of sample calculations show that it is not acceptable applying the Fourier heat conduction model for estimating the temperature of workpiece. Also, it can be perceived that according to the amount of Vernotte number for a specific Fourier number, it is possible that the temperature of different points of workpiece become even lower than initial temperature.