Showing 11 results for Amidpour
Amir Farhang Sotoodeh, Majid Amidpour, Mehrangiz Ghazi,
Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
The purpose of this paper is to reach the maximum energy recovery or maximum cold stream outlet terminal temperature in a plate fin heat exchanger (PFHE) with constant volume and heat transfer area for a specified maximum pressure drop. This paper presents a methodology in surface selection and design of PFHE where full pressure drop utilization is taken as a design objective in constant heat exchanger volume and heat transfer area. Several kinds of PFHE with different fin type and geometries and different heat exchanger width, length and height could satisfy the constant volume and area condition. Setting maximum pressure drop could reduce these several heat exchangers. While the fin type and dimension of each heat exchanger is extracted due to constant volume-area and pressure drop conditions respectively, the terminal temperature of the heat exchanger would be calculated utilizing thermo-hydraulic modeling of the PFHE. A typical gas turbine regenerator is chosen as case study. The methodology is applied to this case study and results are shown. The surfaces which result maximum energy recovery are specified. In the cases that energy recovery of some surfaces would be approximately the same, other parameters such as frontal area and flow length will be considered
Mehrangiz Ghazi, Majid Amidpour, Majid Abbaspour, Hooman Farzaneh,
Volume 15, Issue 8 (10-2015)
Abstract
A new approach of retrofit design methodology in cogeneration heat and power systems based on constructal theory is presented in this paper. A cogeneration system may consist of different turbines, steam levels and steam generators. The steam demand of each level is determined and should be supplied. The purpose of this paper is to retrofit the existing total site heat and power cogeneration system utilizing the concepts of constructal theory. Developing constructal theory to total site cogeneration systems may lead to divide the total site into different constructs. In this paper the total site cogeneration system will be divided into three constructs: turbines, turbine array between each two levels and steam generators array. Using constructal theory simplifies the total site complex system to a simpler system that can be solved easily by a simple search and sort method. The best configuration of the total site would have the minimum operating cost. Using constructal theory would simplify the optimization procedure of cogeneration systems in addition to reach better conceptual design especially in more sophisticated systems. The methodology is applied to a sophisticated total site heat and power cogeneration system as case study from literatures. The constructal retrofit results 14.1% and 14.3% reduction in operating cost and fuel consumption respectively.
Amir Farhang Sotoodeh, Majid Amidpour, Mehrangiz Ghazi,
Volume 15, Issue 12 (2-2016)
Abstract
The modeling and optimization of a rectangular finned multi stream plate-fin heat exchangers is presented in this paper. The proposed method for thermal modeling of this type of heat exchangers is based on uniform heat distribution along the plates. So, the heat streams are distributed along the multi stream heat exchanger based on two principles: equal quantity of stream channel distribution and uniform heat distribution in each of the channels. The geometric, thermal and hydraulic modeling and design of the multi stream heat exchanger is carried out based on rectangular fin specifications. The total annual cost (TAC), the summation of capital investment and operating and maintenance costs are regarded as objective function to be minimized. The main variables are heat exchanger core dimension such as length, width, height and the fin geometric parameters such as fin pitch and height. The genetic algorithm is utilized as optimization tool to minimize the total annual cost of the multi stream plate fin heat exchanger. The proposed method is applied to a case study. The results of the current method is compared with the literatures.
Mohsen Salimi, Majid Amidpour,
Volume 17, Issue 4 (6-2017)
Abstract
In this study, the integration of multi-effect desalination (MED) system with cogeneration of heat and power system has been considered. Low-pressure steam in two case studies has been utilized as the motive steam of MED system. R-curve is a powerful tool that can be used to identify fuel utilization amount in different operation points of the cogeneration system. R-curve explains utility system operation improvement procedure without capital cost. By deploying and development of the R-curve concept, the freshwater demand of the total site and total annual cost of the site have been evaluated. These curves can be used as a tool to improve the operation and economic parameters in every operating point of cogeneration system and present comprehensive view about the improvement of utility system operation condition at each operating point. For the first time, R-curve has been used to identify the impact of cogeneration system integration with a thermal desalination system on the cogeneration system operating point. The performance of the cogeneration system can be either enhanced or impaired by integration of desalination system. As demonstrated in a case study, integration of 2.2 MW MED system can either provide 52.765 MW energy saving or deprive 30.257 MW fuel energy based on the operating state of the cogeneration system before and after integration.
Morteza Mehrgoo, Matin Karbasioun, Majid Amidpour,
Volume 17, Issue 5 (7-2017)
Abstract
Optimum design and performance improvement of the Heat Recovery Steam Generator (HRSG) have noticeable effects on the thermal efficiency of the combined cycle power plants. Therefore, HRSG must be designed in such way that maximizes the heat recovery and improves the overall performance of the plant.
In this paper, a method for design and optimization of a triple pressure HRSG is proposed. It is shown how to simultaneously optimize the operating and geometric design parameters of the HRSG by using the constructal theory. Considering the minimum total entropy generation as the objective function, the optimum parameters in the HRSG unit are derived by using the genetic algorithm method under the fixed total volume condition. Optimized total volume is derived by converting the exergy destruction to cost of entropy generation in order to compare with the capital cost and the results show that there is a trade-off between them. Also, aspect ratios of the units, the heat transfer area for each component of the HRSG and thermodynamic properties are significant features of the flow configuration inducted by the Constructal design. Furthermore, the effects of changing in the temperature and flow rate of hot gas on the optimal values of the total volume, power and steam production are determined.
Amir Farhang Sotoodeh, Mehrangiz Ghazi, Majid Amidpour,
Volume 17, Issue 8 (10-2017)
Abstract
In contrast with two stream heat exchangers, the three stream ones owns much more complexity in design and rating and a comprehensive rating method has not been proposed, yet. In this paper, a new rating method is presented in order to be used in three stream plate – fin heat exchangers. Rating, in heat exchangers, means finding out the heat load of the heat exchanger or in the other words calculating the outlet temperature of each stream and furthermore, finding out the pressure drops of each stream. In this paper, the differential equations of energy conservation and heat balance of each steam is extracted and a set of differential equations in terms of outlet temperatures in constructed. The general solution of this set of equations is then extracted. In order to expand the general solution to plate – fin heat exchangers, the geometric, thermal and hydraulic modeling are applied based on fin geometric specification which used rectangular type in this paper without losing generality. Based on all of the extracted equation, a comprehensive algorithm of rating of the three stream plate – fin heat exchangers is presented. In order to evaluate the presented algorithm, a case study is used and the results will be shown. Furthermore. A parametric study is applied to the case study to evaluate the effects of the geometric parameters of the fins such as height and frequency on heat load and pressure drop of the heat exchanger.
Volume 18, Issue 2 (3-2016)
Abstract
In order to determine the best growing media for Gerbera jamesonii under alkaline conditions, a factorial experiment was conducted with two factors, namely: (i) Growing medium, and (ii) Concentrations of bicarbonate (NaHCO3) in nutrient solution. Results showed that increasing the concentration of NaHCO3 from 0 to 40 mM in nutrient solution significantly decreased plant growth, maximal quantum yield of PSII photochemistry (Fv/Fm), photosynthesis Performance Index (PI), Glutamine Synthetase (GS) activity, Leaf Relative Water Content (LRWC), Chlorophylls (Chl a, b and total Chl) and carotenoids. Under alkalinity stress, reduction in vegetative growth, Fv/Fm, PI, LRWC, GS activity and photosynthesis pigments content was the lowest in Coconut Fiber (CF) substrate compared to the other substrates. Furthermore, plants grown in CF substrate had higher soluble sugars and proline content than those in other substrates. On the other hand, plants grown on Perlite (P) substrate had the highest reduction in growth and physiological characteristic in alkaline conditions. The alleviation of alkalinity-induced growth inhibition of plants by CF substrate may be related to improvement of photosynthesis, enhancement of GS enzyme activity and osmotic regulation. It is concluded that the use of CF substrate could provide a useful tool to improve alkalinity tolerance of gerbera plants under NaHCO3 stress.
Volume 18, Issue 3 (5-2016)
Abstract
A greenhouse study was carried out to determine the effect of nitrogen forms and different O2 levels on growth and mineral nutrient concentrations of eggplant. The experimental design was a completely randomized factorial experiment with two factors, namely: (i) Two nitrogen forms (Ca(NO3)2 and (NH4)2SO4) and (ii) Three O2 levels of the nutrient solutions (1±0.3, 2±0.3, 3±0.3, and 4±0.3 mg L-1 O2). The results showed that ammonium application reduced all measured parameters of vegetative growth, whereas high oxygen levels increased the vegetative growth. Comparing with nitrate-N, ammonium application increased the concentrations of NPK and Zn in leaves and Zn and Cu in roots, while it decreased the concentration of Mg, Ca, Cu, Mn, and Na in leaves and Ca, Mg, Mn, and Na in roots. High levels of O2 increased N, Mg, Ca, Cu, and Mn content of leaves, as well as Mn and Na content in roots, while it decreased the concentration of K in leaves and P and Zn in roots. According to the results, the increase in O2 amount of the nutrient solutions partly alleviated ammonium toxicity in eggplant. Therefore, in floating hydroponic cultures, O2 level and its distribution should be controlled and must not be lower than 4 mg L-1.
M.j. Rahimi, M.h. Hamedi, M. Amidpour,
Volume 19, Issue 6 (June 2019)
Abstract
The present paper presents the results of the thermodynamic and economical study of the use of synthesis gas from a biomass gasification reactor instead of natural gas at a synchronous power plant. First, the analysis of the system at the Pars factory, which is fed with natural gas, was done, and the use of a for the synthesis of natural gas for the replacement of natural gas is investigated. The results of thermodynamic analysis indicate that the increase in the percentage of biomass fuel moisture had a slight effect on CH4 and N2 in synthetic gas, but it has a relatively modest effect on CO and CO2 thermal value. By using a reactor, a natural gas consumption of 4468316cubic meters per year will be saved. The results of economic analysis indicate that due to the price of natural gas of 700Rials per cubic meter, the purchase price of electricity is 650Rials per kWh, the number of years of operation 7 years and the profit rate of 7%, the net present value is at the zero frontier and this investment is at the threshold of being economically feasible. But if the rate of profit is to be raised, the lower the natural gas purchase price, or of electricity purchase, the improved system from the economic point of view is not profitable. In this regard, at a profit rate of 7%, the price of the biodegradable fuel is at most equal to 100,000 rials per ton, the net present value is at the zero frontier and the investment will have economic justification, But in larger quantities of biomass, investment will not be economically profitable.
R. Rastgar , M. Amidpour , M. Shariati Niasar,
Volume 19, Issue 7 (July 2019)
Abstract
Despite recent improvement in energy efficiency of diesel engines, more than 50% of the energy input is lost as waste heat in the form of hot exhaust gases, cooling water, and heat lost from hot equipment surfaces. Exhaust pollution from internal combustion engines can potentially result in severe damages on earth atmosphere, including ozone depletion, global warming, and significant health problems. Waste heat recovery based on Rankine cycle has been identified as a potential solution to increase the energy efficiency and consequently to reduce the engine emissions. In this rather low cost technology, waste heat is recovered in a Rankine cycle, aiming to convert mechanical power into electrical power. Output electrical energy is stored in a battery and can be used in electric usages. In this paper, the possibility of using the exhaust heat recovery system without utilizing the heat of other recyclable materials has been investigated, using the organic Rankine cycle (ORC), in order to increase the efficiency of the diesel engine of the bus. Depending on amount of achievable heat of exhaust, in some performance point of diesel engine, the amount of fluid flow rate and output power of Rankine cycle was calculated. Our results exhibit 5.1 KW increase in the diesel engine power resulting in 1.12% increase in energy efficiency in engine part load condition. The output mechanical power from the micro-generator is converted to electrical power and is stored in an energy storage system. The storage energy can be utilized to supply power for electrical equipment such as fans, bulbs, and also phone chargers of passengers.
Volume 22, Issue 6 (11-2020)
Abstract
In order to compare the effect of three nutrient solution replacement methods in an NFT system and pruning on hot pepper, a factorial experiment was conducted. Factors included nutrient solution replacement method (complete nutrient replacement, partial nutrient replacement according to EC, and partial nutrient replacement according to plant requirements) and pruning (pruning and non-pruning). Results showed that the highest vegetative growth was recorded in plants fed by complete replacement of nutrient solution, while plant fed based on EC showed the lowest vegetative growth and nutrients concentration. Leaf Chlorophyll a (Chl a) and Total Chlorophyll (TChl) decreased in plants fed according to EC control and plant requirements compared to complete replacement of nutrient solution. All these traits were higher in non-pruned plants than in pruned plants. Fruit yield decreased in plants fed based on nutrient solution EC and plant requirements, and pruning treatment decreased these traits, but the highest single fruit weight belonged to pruned plants fed based on plant requirements. The highest fruit carotenoid content, Total Soluble Solids (TSS), and vitamin C were recorded in plants fed according to nutrient solution EC, and these traits were higher in the pruned plants compared to non-pruned ones. The results also showed that pruning caused a reduction in plant growth and fruit number, therefore, it is not recommended for hot pepper cv. Sentela.
