نشریه انرژی ایران
سال دوازدهم شماره 3 (پیاپی 44، پاییز 1388)

Transformers are used in power systems for transmission and distribution of electrical energy in long distance. Also, reliability of transformers have essential role in feed of electrical energy. Therefore it is necessary to identification of faults in transformer. One of this faults that is difficult to recognize is mechanical deformation in transformer windings. Now a day, only method to identification of this fault is measuring of transfer function. In this paper, transformer winding is simulated by transfer function for monitoring. For this aim, the detailed model of windings is used and has been showed this model able to identification and simulation of mechanical deformation in transformer windings. Finally, it has been showed with simulation with detailed model and also by using of transformer transfer function can be recognized mechanical deformation in transformer windings. Meanwhile, this method could be recognized the location of this fault

After the economic development of the country, the demand of electrical energy is increasing. Nowadays, industrial communities are interested in replacement induction motors with new motors like Switched reluctance motors and permanent magnet motors. Induction motors consume a large amount of energy and have low efficiency.Switched reluctance motors are belong to reluctance motor. The main specifications of these motors are: motor efficiency is more than the other types and its structure is simple so that it has windings just in stator.Domestic water coolers are one of the most common appliance in the home and consume a lot of energy. Replacement of induction motors with SR motors result in decreasing energy consumption and convenient control. In new design, rate of cooling can be adjusted continuously by tuning the value of motor speed.

Emission factors of CO2, SO2 and NOx emitted from Iran's thermal power plants are fully covered in this paper. To start with, emission factors of flue gases were calculated for fifty thermal power plants with the total installed capacity of 34,863 MW regard to the power plants operation characteristics including generation capacity, fuel type and amount and the corresponding alterations, stack specifications, analysis of flue gases and physical details of combustion gases in terms of gKWh-1. This factor was calculated as 640, 2.75 and 2.4 gKWh-1 for CO2, SO2 and NOx respectively. To achieve an accurate comparison, these values were compared with their alternatives in North American countries. According to this comparison, emission factor of flue gases emitted from Iran's thermal power plants will experience an intensive decline if renewable, hydroelectric and nuclear types of energy are more used, power plants efficiency is increased and continuous emission monitoring systems and power plant pollution reduction systems are utilized.

In this paper energy saving potential and environmental impacts for household electric water heaters are studied. at the first step the basic parameters and measurement method based on standard IEC379 are chosen. Then twelve domestic electric water heaters are tested. By using the regression method the best curve are fitted and by shifting the base curve the region between upper and lower limits are divided into seven regions for various capacities. Energy saving potential are calculated by comparing to insulated electric water heaters. Economical appraisal from consumer and national economy point of view are studied.

Production of Cement Industry has experienced a noticeable rate of growth in Iran in recent years. Cement Industry, between energy intensive industries, after iron and steel industry, is the most energy intensive sector in Iran economic and it is expected that the growth of energy consumption in this sector as fuel will continue in future. So, precisely forecasting of long run energy consumption in this industry and specification of the potential of energy saving in result of technology progress in this sector; are crucial. Thus, in this paper, the amount of energy consumption and the amount of energy saving because of technology improvement in cement industry during 2005 - 2025 is estimated by using of Model for Energy Demand Evaluation. Introducing of Model for Energy Demand Evaluation Methodology in Simulation of Energy Demand in Cement Industry, running of model and estimation of long run energy demand in cement industry and analysis of it’s results, impact of improvement in cement industry production technology on energy consumption in this sector and the impact of unemployment controlling policy or accelerate economic growth policy on energy demand in cement industry; are the contents of this paper. Results of estimated model appear that the energy saving potential because of technology improvement in cement industry is very high and in 2005, 2015 and 2025 sections is equal to 0.64, 3.1 and 8.6 MBOE respectively. Because of this high energy saving potential, the cement industry must be one of the first industry for energy consumption optimization projects.

The goal of this paper is calculating the cost price of one KiloWatt-hour of electric energy with different scenarios such as United Nation's Method and Long Run Marginal Cost.The outcomes show that the price of one KiloWatt-hour electric energy based on current expenses and the sum of current and investment expenses in 1387 equals 266 Rials and 397.6 Rials respective.Furthermore, the price of one KiloWatt-hour electricity in the basis of United Nations's Method in that year equals 708.7 Rials. Thus considering the opportunity cost, the cost price of one KiloWatt – hour electricity will increase up to four times in comparison with this cost regarding the accounting method.

This paper discusses the simulation of the Photovoltaic/Thermal (PV/T) air systems with natural air flow operation for both glazed and unglazed types. Comparisons are made between the theoretical and experimental results and good agreement between these two values are obtained. Additionally, the influence of the glass cover on the different system parameters has been evaluated. Results show that setting glass cover on photovoltaic panels leads to an increase in thermal efficiency and decrease in electrical efficiency of these systems.