فصلنامه مهندسی و مدیریت انرژی
سال دهم شماره 2 (پیاپی 36، تابستان 1399)

With the electricity industry restructuring along with the increasing expansion of renewable energy sources, the uncertainties in the system have increased. This has led to increased attention to electricity producers’ bidding methods. A new method has been proposed in this paper for the profit-based self-scheduling of a generation company (Gen Co.) comprising a compressed air energy storage (CAES) along with wind and thermal power plants. stochastic optimization has been used in the proposed algorithm due to the uncertainties of parameters like energy and spinning reserve prices, the amount of called-on reserve, the imbalance cost and wind power generation,. The Gen Co’s optimal bids for energy and spinning reserve markets are obtained. The proposed method is initially applied to a test system from another paper; comparing its results with the results of the previous method demonstrates the capability of the proposed method in the scheduling of CAES units. Finally, the data of a real power system are used to present the complementary results of the proposed algorithm.

With the rapid growth of wind power plants, different types of these resources are connected to the network at different voltage levels. A number of these resources have DFIG. The development of distributed generation has made problems such as an increased level of short circuit and the loss of protective devices coordination. During the fault occurrence, transient stability may be lost due to drastic changes in speed, power, and rotor angel of synchronous and asynchronous generators. Based on the dependence of resistance and temperature, high-temperature superconducting fault current limiter could decrease the fault current. This paper, after studying the ability of HTSFCL to reduce the fault current and to increase the stability level in PSCAD/EMTDC software, for the first time proposes objective function of HTSFCL optimal location by simultaneously considering security and protection coordination indices, voltage, and transient stability of synchronous and asynchronous generators in the networks connected to DFIG. Optimal location and size of HTSFCL in IEEE 30-bus test network are determined using differential evolution (DE) algorithm in MATLAB while considering single- and multi-objective indices. Also, indices of security, coordination of overcurrent relays, voltage stability, and rotor angel stability are compared in six modes. The achieved results show the applicability of the proposed method.

Energy optimization and consumption analysis is the first step in realizing smart houses. This paper incorporates the uncertainty of the effective parameters and probabilistically optimizes the energy consumption in a building. To this end, probability density functions (PDFs) of building uncertain parameters are modeled by empirical rule method and the energy usage in buildings is optimized. Energy-Plus and MATLAB softwares are respectively used to compute energy consumption in a building and to optimize energy consumption. Energy consumption of the building and the thermal comfort are considered as objective functions of the proposed multi-objective optimization problem. A 12-storey commercial building is used as a case study. The proposed probabilistic method is compared with the deterministic method to assess the proposed method,. The results show a significant difference between the deterministic and probabilistic cases. The maximum difference between the mean optimal values of variable parameters in these cases is about 34%. Finally, sensitivity of the results to the climate changes is also investigated in this paper.

Solar chimney power plants which use a simple technology to generate electricity are comprised of three main parts which are collector, tower, and turbine. The power plant using chimney effect converts solar radiation into kinetic and, then, electrical energy. Although the initial cost is considerable, the plant has great advantages such as low depreciation and the lack of a need for water; that is why many efforts have been directed to the modeling, designing, and alike about these plants. One important subject in this area which is studied in this article as well is the optimization of plant-location. To this end, we have developed an in-house simulator which models the whole plant at an unsteady state. The simulator was verified by comparing its results with the experienced collected data from Manzanares power plant, built in Spain. The negligible differences between experienced data and simulation results verified the developed simulator. Then the in-house simulator was used to model the performance of that plant for five cities in Iran, (Shiraz, Bushehr, Kerman, Tehran, and Mashhad). Our studies have showed that building such plants in Shiraz, among these cities, will be the most efficient.

The objective of this research is to study the effect of energy price on the prices of houses in Iran. Accordingly, based on Breitenfellner et al. mode (2015) l and through the deployment of Johansen- Juselius method, the writers have examined this issue from the first quarter of 2006 to the fourth quarter of 2014. The research results indicate that the coefficient of all variables of the model have been as the expected theoretical principles and energy price has a significant and negative impact on house price. Accordingly, since the financial market and monetary policy function as the channels through which energy price affect housing price and financial markets play roles in absorbing the liquidity of speculators, it is recommended that economic planners attempt to strengthen the markets and reform the public culture to pay more notice to investing in financial assets rather than buying real states and, thus, increase energy price and inflation. In other words, by absorbing the liquidity of speculators, a step is taken toward controlling house price. Also, it is recommended that Central Bank pay more attention to the selection of right tools to implement monetary policies to deploy correct monetary policy at time of an increase in energy price and inflation to control house price.

One of the most useable parts and, in fact, the heart of a Hybrid vehicle is its Lithium Bromide battery. In these batteries, a large quantity of heat is generated, and if this heat is not managed properly, the useful cycle life of the battery will be reduced progressively. Thus, the vital issue of these batteries is their cooling. Since the Phase Change Material (PCM) absorbs a great deal of energy due to its Latent heat capacity during its melting process, PCM can wonderfully be effective for quick and great heat dissipations. Hence, in this paper, it is tried to investigate the simultaneous effects of the application of PCM and fins on the cooling process of these hybrid batteries; in other words, it is tried to present the optimum fin sizes to minimize the battery temperature rise during its recharge process. The results indicate that 6-fin batteries show the highest performance when the fin length is 11.67mm.

In order for an accurate recognition of the constraints, barriers, and facilities obtainable for the use of energy supplies in any country, it is necessary to calculate the amount of utilization of surviving energy potential and the method of transforming these energies through a scientific and precise manner. Typically used photovoltaic systems limit the employment on curved facades. Throughout this analysis, a photovoltaic system based on plastic, small-scale solar panels were designed, manufactured, and evaluated techno-economically. Due to the importance of effective variables, a temperature sensing system was designed and made for an on-line data reception and connection with the computer code, and data from the meteorological station, and NASA were collected. Taguchi Analysis was used to characterize the “more cost-efficient, better” goal for selecting the top system. Cost-benefit analysis of the systems within the COMFAR package was performed: the internal rate of return on the flat, cylindrical, and hemispherical surfaces was 23.82 and 26.70 and 27.46%, respectively. The net present value is equal to 6.74 and 9.95 and 10.83 million Rials. If the system on the flat surface under the standard conditions has a coefficient of 0.73 and the most power production capacity of about 46.71 W with a yield of seven.09%, the system supported the cylindrical and hemispheric surfaces has a coefficient of 0.88 and 0.84, respectively, with the most power production of 55.18 W and 57.50 W, with a yield of 7.45% and 7.55%, respectively. These Systems have an economic justification for attracting capital.

Axial vane rotary engine (AVRE), as a novel type of rotary engines with special and exclusive features, is still under research in some of the reliable engine research centers around the world. The engine is a positive displacement mechanism that permits the four "stroke" action to occur in one revolution of the shaft with a minimum number of moving components in comparison with reciprocating engines. In this paper, a two-zone combustion model is developed for a spark ignition axial vane rotary engine. Spark ignition engine cycle simulation has been performed on the equivalent four stroke reciprocating engine of the AVRE engine. In this paper, the effect of compression ratio, blowby coefficient, and engine speed on the maximum pressure and temperature of the AVRE are investigated. The modelling is based on equations for energy and mass conservation, equation of state, and mass fraction burned. Combustion chamber is divided into burned and unburned zones, and differential equations are developed for the changes in pressure and changes in temperature in each zone. The developed code for engine simulation in MATLAB is applied to another engine and there has been a good agreement between results of this code and the results related to the engine chosen for validation.

This paper has investigated a simulation and numerical study of the flow field and temperature distribution in a room with inorganic insulation with a floor heating system. The air in the room is considered incompressible, and the modeling turbulent flow and radiation heat transfer are modeled by disturbance k-ε (RNG) and DO radiation models, respectively. Piso algorithm is used for solving the governing equations. The results indicate that the best position for insulation in the floor heating system is in the external walls of the building. It has been found that paint with ceramic coatings can lead to 18% savings in energy consumption in the winter than the conventional paint. Also, the impact of external wall insulation with floor heating system in different climates has been investigated. It has also been found that hot and humid, hot and dry and humid temperate climates provide better thermal comfort conditions for the residents and that the lowest energy consumption is related to the hot and humid climate.

In this paper, the performance of four prevalent combined ejector-vapor compression cycles are compared. A non-iterative algorithm for the analysis of ejector performance in critical operational mode has been used. Moreover, using flow parameters is proposed for estimating loss coefficient in the mixing process rather than using geometrical specification and operating conditions of the ejector. The effects of the operating conditions and refrigerant type on the coefficient of performance, thermal coefficient of performance, and ejector entrainment are investigated and analyzed. Results show that, at high condenser temperatures, the difference between coefficient of performance of combined cycle and conventional vapor compression cycle significantly decreases. Combined cycles which only utilize the waste heat of the condenser in the vapor compression sub-cycle have a lower coefficient of performance than those cycles using an external heat source and can be used in smaller rang of condenser and generator temperatures.