جستجوی مقالات مرتبط با کلیدواژه "میکروتوربین" در نشریات گروه "مکانیک"

In this study, the combustion performance of C30 microturbine combustion chamber with biogas fuel with different mass fractions of CO2 has been analyzed and investigated. By assuming the periodic geometry and the two-stage reaction of fuel and oxide, the computational cost was reduced. To simulate the flow inside the chamber, three-dimensional Navier-Stokes equations and the k-ε turbulence model have been used to model the effects of turbulence. The flow inside the combustion chamber with different fuel components was analyzed with the EDDY DISSIPATION combustion model. To validate the solution and compare the results with the fabricated sample, pure CH4 was used as fuel. In this study, it was found that in the case of a constant mass flow rate of the consumed fuel, increasing the share of CO2 in the fuel with different mass fractions, due to the decrease in the calorific value created, caused a decrease in the production temperature, and it was also found that the use of biogas as a premix caused a decrease The amount of NOx becomes desirable. According to the obtained results, it is suggested that the amount of CO2 in the fuel is at most 10%, because the temperature has decreased by only 38 Kelvin and the amount of NOx in the output is 1.4 ppm.

Combustion chamber has a crucial role in gas turbines and has a significant effect on the pollution and efficiency of them. Due to the complicated flow in combustion chambers because of high turbulence intensity, flow mixing, and flame behavior, prediction of the performance of such chambers is very complicated. There is a vital need for experimental investigations to study and understand the flame behavior in combustors. This experimental study was performed using a can type combustion chamber and LPG fuel at atmospheric conditions. First, stability curve, temperature distribution in the combustion chamber, and its exit plane in 6 flow conditions and then flow behavior were evaluated. The pollution at the outlet was obtained in different conditions and equivalence ratios. The results show that the flame tends to go downstream of the combustion chamber when the fuel mass flow rate increases (or in other words, by increasing the equivalence ratio) in constant air mass flow rate and finally exits from the chamber. By increasing the air mass flow rate in constant fuel mass flow rate, CO pollution is increased, and NOx pollution is decreased.

In this paper, a Regenerative Organic Rankine Cycle (RORC) for micro-turbine waste heat recovery is modeled and optimized. Refrigerant mass flow rate, Micro- turbine nominal capacity, evaporator pressure, turbine outlet pressure and regenerator efficiency are considered as design parameters. Four refrigerants including R123, R134a, R245fa and R22 are selected and used as working fluids in cycle. Then, NSGA-II (Nondominated Sorting Genetic Algorithm) is used to maximize the thermal efficiency and minimize the total annual cost (including investment cost, fuel cost and environmental cost. The results of the optimal design are a set of optimum solutions, called Pareto front. The optimization results show that the best working fluid is R123 in both of economical and thermo dynamical view point. The optimum result of R123 shows the 3.70%, 18.77%, and 19.74% improvement in thermodynamic efficiency compared with R245fa, R134a, and R22, respectively. The corresponding values for the total annual cost are obtained 6.7%, 10% and 24%, respectively. Generally, it seems that fluids with zero and positive slope of vapor saturation curve have higher thermal efficiency and lower total annual cost. In addition, it is observed that micro-turbine efficiency increased by 12% by the implementation of regenerative organic rankine cycle.

Small-scale cogeneration systems, by using the micro-turbines, have provided required electricity and heat in Hotels and residential complexes over the years. Hotels with CCHP system has higher energy efficiency compared to other energy systems, since usescogeneration waste heat for heating and cooling applications. The main advantages of cogeneration systems are reduction in fuel consumption, lower greenhouse gas emissions and environmental pollutions. In this study, it was tried to further introduce these systems, their function and economic analysis at the national level, in order to extend their usage in different places such as office, industrial, commercial and residential complexes. One method is to use solar radiation to provide part of energy required for water heating. Energy consumption pattern in a large hotel over the years was considered and economic analysis was performed for different energy consumption scenarios. Payback period were computed of each scenario, in order to make a positive attitude towards the use of cogeneration systems utilizing solar energy.

Micro turbines are indeed very small gas turbines (25-300 kW) that usually have thermal regenerator or recuperator to minimize the energy consumption. In currently working plants, the air entered into the compressor is compressed and then is preheated using the heat of turbine exhaust gases in a recuperator. One of the methods to enhance the performance of the gas turbine is using a heat exchanger to recover the energy of hot gases leaving from gas turbine. To recover heat in gas turbine industry different devices have been used. In general, heat recovery devices are divided into two groups i.e. i) regenerators and ii) recuperators. Regenerators act periodically and at the first time interval it absorbs the heat of turbine exhaust gas in the heat exchanger matrix and in the next time interval transfers heat to the cold dense air leaving the compressor. In contrast, Recuperators are heat exchangers that transfer heat into compressed air continuously and use the energy of exhaust hot gases. This paper investigates the thermodynamic of microturbine. The results show that adding a recuperator increases the cycle thermal efficiency significantly. Also this paper investigates the effect of recuperator materials on the micro-turbine performance and the turbine inlet temperature as the most effective factor to increase the performance. The thermodynamic equations were solved by an engineering software EES2013. Considering the results show that at the pressure ratio of 4.29 the thermal efficiency is maximum and adding a recuperator decreases the fuel consumption rate 45 percent in the combustion chamber.

In this paper, multi objective genetic algorithm is applied to optimize one type of recuperator in a 200 kW microturbine by considering two key parameters such as recuperator efficiency and cost. ε-NTU method is selected for the recuperator efficiency and pressure drop calculation. The recuperator total cost consists of capital cost, operational cost and maintenance cost. A plate-fin heat exchanger with offset strip fin for counter and cross flow arrangements is chosen for optimization. Fin pitch, fin height, fin offset length, cold stream flow length, non-flow stream length and hot stream flow length are considered as six design parameters. NSGA-II (Non-dominated Sorting Genetic Algorithm) is conducted to maximize recuperator efficiency and minimize its total cost. Results of the optimization are presented as a set of designs, called ‘Pareto-optimal solutions’. The results reveal the confliction between the two objective functions. It can be concluded that any change in the geometry of the recuperator increasing the efficiency also increases the total cost and vice versa. Finally, the optimal designs are compared together based on non-dominated sorting concept and the final optimal designs are obtained.

The aim of this study is designing the impeller of a centrifugal compressor in order to supply pressure ratio for a 65 kW micro gas turbine. First, the primary thermodynamic analysis has been conducted for the considered cycle using a home made code. Herein, the compressor pressure ratio was considered to be 4. The obtained thermal efficiency was 25.64%. Then, the design of micro compressor in 90,000 rpm rotational speed was conducted and its dimensions were extracted. The designed micro compressor has 9 main blades and 9 splitter blades. The outer diameter of the compressor impeller was 95.5 mm. Then, the three-dimensional geometry of the compressor impeller was extracted. Finally, to validate the designed impeller, CCD software was used and CFD analysis has been conducted on generated geometry, using CFX.

This paper is concerned with the influence of blade angles on centrifugal impeller performance parameters such pressure ratio, diffusion ratio and efficiency. The other basic geometric parameters are held constant. The influence of the blade angles change on the observed values was determined from numerical solution of the flow in the impeller with help of the FLUENT software. The numerical simulation focused on the air flow from compressor impeller inlet to exit, and the performance of impeller is predicted. The numerical solution was performed for original impeller geometry and for two other cases, in which blade inlet angle and backward sweep was changed.The standard k −ε turbulence model was used to obtain the eddy viscosity. Performance of the code was verified using measured data for the Eckardt impeller.

Full Load Thermoeconomic and environmental optimization of a hybrid Solid oxide fuel cell-Micro gas turbine system for use in distributed power generation has been investigated in this paper. For this reason, a multi objective optimization approach based on genetic algorithm has been incorporated. The hybrid system has been simulated in a computer code and all performance related results for assumed Decision parameters has been validated using available literature data. Decision parameters are calculated in the optimization procedure with respect to the system constraints, to reach the optimum criteria for both Exergetic and Economic Objective functions while the Environment damage penalty is also added to the system total Cost. Effects of fuel unit cost, capital cost and System output size on optimum results has been considered. it is clear from the results that the most sensitive and important design parameter in this system is the fuel cell's current density which it's careful chose has significant effect on the balance between cost and performance of the system.