Assessment of the energy and exergy utilization efficiencies in the Turkish agricultural sector

This study deals with evaluating the energy and exergy utilization efficiencies in the Turkish agricultural sector over a 12‐year period from 1990 to 2001. In the energy and exergy analyses, two main energy sources, namely fuels and electricity, are taken into consideration, while the sectoral energy and exergy efficiencies are compared for this period. These main energy sources include diesel for tractors and other vehicles, and electricity for pumps. Overall energy utilization efficiencies are obtained to vary between 29.1 and 41.1%, while overall exergy utilization efficiencies are found to range from 27.9 to 37.4% in the analysed years, respectively. It may be concluded that the present technique proposed here may be used as a useful tool in analysing and evaluating the energy and exergy utilization efficiencies, identifying energy efficiency and/or energy conservation opportunities and dictating the energy strategies of countries. Copyright © 2005 John Wiley & Sons, Ltd.     

Energetic and exergetic aspects of cotton stalk production in establishing energy policies

Exergy analysis is important for energy resource utilization, because exergy, which is a way to a sustainable future, is a part of the energy analysis. Exergy analysis starts to play a role in several countries in developing energy policy. This paper deals with the exergetic assessment of the cotton stalk (CS) production. In this regard, Turkey, which is one of the eight countries producing 85% of the world's cotton, is given as an application country first. Energy and exergy relations used in the analysis are then presented. Finally, the Turkish CS production in 2003 is evaluated using energy and exergy analyses method, while the results obtained are discussed. The values for the net energy and exergy gained are obtained to be about 49,146 and 59,395 MJ/ha, respectively. Turkey's total energy and exergy are estimated to be 75.45 and 81.87 PJ. It may be concluded that this amount of energy is equal to 7.77% and 2.38% of Turkey's primary energy production and consumption in the same year, respectively. The overall mean energy and exergy efficiencies of the cotton production in the year studied are found to be 33.06% and 33.12%, respectively. It is also expected that the results of this study will be helpful in developing highly applicable and productive planning for energy policies.     

The effect of biodiesel fuel obtained from waste frying oil on direct injection diesel engine performance and exhaust emissions

In this study, usage of methyl ester obtained from waste frying oil (WFO) is examined as an experimental material. A reactor was designed and installed for production of methyl ester from this kind of oil. Physical and chemical properties of methyl ester were determined in the laboratory. The methyl ester was tested in a diesel engine with turbocharged, four cylinders and direct injection. Gathered results were compared with No. 2 diesel fuel. Engine tests results obtained with the aim of comparison from the measures of torque, power; specific fuel consumptions are nearly the same. In addition, amount of emission such as CO, CO₂, NO_x, and smoke darkness of waste frying oils are less than No. 2 diesel fuel.     

Turkey's sectoral energy and exergy analysis between 1999 and 2000

This study analyses sectoral energy and exergy utilization in Turkey between 1999 and 2000. Total energy and exergy utilization efficiencies are calculated to be 43.24 and 24.04% in 1999, and 44.91 and 24.78% in 2000, respectively. In order to calculate these efficiency values, Turkey is subgrouped into four main sectors, namely utility, industrial, transportation and commercial‐residential. The energy efficiency values are found to be 23.88, 30.10, 68.97 and 57.76% in 1999, and 23.71, 30.11, 68.81 and 57.05% in 2000 for transportation, utility, industrial and commercial‐residential sectors, respectively. Besides this, the exergy efficiency values are obtained to be 23.80, 30.28, 35.97 and 8.12% in 1999, and 23.65, 30.47, 35.51 and 8.02% in 2000 for the same order of sectors. The present study has clearly shown the necessity of the planned studies towards increasing exergy efficiencies in the sectors studied. Copyright © 2004 John Wiley & Sons, Ltd.     

Performance Analysis and Assessment of an Industrial Dryer in Ceramic Production

In recent years, exergy analysis has been widely used in the design, operation, and performance assessment of various thermal systems, among which drying, which is an energy intensive operation, is of a great importance. In the ceramic industry, it is aimed at utilizing a minimum amount of energy in order to remove the maximum moisture for the desired final conditions of the product to be dried. In this study, energy and exergy analyses of a ceramic plant, located in Izmir, Turkey, with a yearly production capacity of 24 million m² were performed using the actual operational data over a period of 12 months. The drying system at the three stages was analyzed and the values for exergy destruction and efficiency for each component of the system and the whole system at a reference (dead state) temperature of 22°C were calculated. For the month of January, energy and exergy efficiencies for the spray dryer (SD) were determined to be 65.50 and 53.7%, respectively. Energy and exergy efficiency values of the vertical dryer (VD) were 45.12 and 43.3%, respectively, and those of the furnace (F) were 35.08 and 16%, respectively. Based on this one-year assessment, the energy efficiency values for the SD, VD, and F varied between 58.48 and 65.50%, 42.44 and 50.87%, and 30.44 and 36.99%, and the exergy efficiency values were in the range of 44.85–65.16%, 34.92–45.42%, and 12.73–16.41%, respectively.     

An Application of Genetic Algorithm Search Techniques to the Future Total Exergy Input/Output Estimation

Since 1975, there has been a great deal of interest, particularly during the past decade, in the promising genetic algorithm (GA) and its application to various disciplines from medicine to cogeneration. However, the studies performed on energy-related GA modeling are relatively low in numbers. The main objective of the present study is to develop the exergy input/output estimation equations in order to estimate the future projections based on the GA notion. In this regard, the GA Future Total EXergy Input/Output Estimation Models (GAFTEXIEM/GAFTEXOEM) are used to estimate total exergy input/output demand of Turkey, which is selected as an application country, based on the economic and social indicators of gross domestic product (GDP), population, import, export and house production figures. The future prediction of Turkey's total exergy input/output values are projected between 2003 and 2023. It may be concluded that the models proposed here can be used as an alternative solution and estimation techniques to available estimation techniques. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.     

Conventional and enhanced exergy analysis of a hydrogen liquefaction system

In the present work, conventional and enhanced exergy analyses were applied to the cryogenic liquefaction process of hydrogen gas. The hydrogen liquefaction unit consists of a multi-stage compressor, booster compressor-turbine pair, and heat exchanger block. Convectional exergy analysis cannot identify parts of exergy inefficiencies. In addition, by convectional exergy analysis, it cannot determine inevitable exergy losses that occur due to technological limits. For this reason, enhanced exergy analysis should be applied to the system. The exergy destruction affecting the exergy efficiency of the hydrogen liquefaction unit was investigated in detail. This study suggests an enhanced exergy analysis of a cryogenic liquefaction system. According to the results of the convectional exergy analysis, exergy efficiency of the whole liquefaction process are 32.22%. Also, the highest and lowest endogenous exergy destruction among whole components is calculated as 9563 kW and 92.83 kW in the turbine and CM-1, respectively. With these calculated results, the potential for improvement in the turbine in the liquefaction system was found to be high.     

Exergoeconomic aspects of sectoral energy utilization for Turkish industrial sector and their impact on energy policies

This study deals with this thermo-economic analysis of energy utilization in the industrial sector (IS) towards establishing energy policies. The relations between capital costs and thermodynamic losses for subsectors in the IS are investigated. In the analysis, Turkey is taken as an application country based on its actual data over the period from 1990 to 2003. Energy and exergy analyses are performed for eight industrial modes, namely iron–steel, chemical–petrochemical, petrochemical–feedstock, cement, fertilizer, sugar, non-metal industry, other industry. The energy and exergy utilization efficiency values for the entire Turkish IS are obtained to range from 63.45% to 70.11%, and from 29.72% to 33.23%, respectively. The ratio of thermodynamic loss rate-to-capital cost values is also calculated to vary from 0.76 to 1.01.     

Evaluation of Biodiesel Fuel Obtained from Waste Cooking Oil

Abstract

In this study, usage of methyl ester obtained from waste cooking oil (WCO) is evaluated as an alternative energy source. Potential of obtained biodiesel from WCO in the World and Turkey was determined. Physical and chemical properties of methyl ester were determined in the laboratory. The methyl ester was tested in a diesel engine with turbocharged, four cylinders and direct injection. Obtained results were compared with No. 2 diesel fuel. In addition, if WCO is evaluated as biodiesel, environmental pollution caused by waste cooking oil diminished.     

Energy and exergy analyses of a raw mill in a cement production

Cement production has been one of the most energy intensive industries in the world. In order to produce raw materials preparation, clinker and rotary kilns are widely used in cement plants. The objective of this study is to perform energy and exergy analysis of a raw mill (RM) and raw materials preparation unit in a cement plant in Turkey using the actual operational data. The RM has a capacity of 82.9 ton-material hourly. Both energy and exergy efficiencies of the RM are investigated for the plant performance analysis and improvement, and are determined to be 84.3% and 25.2%, respectively. The present technique is proposed as a useful tool in the analysis of energy and exergy utilization, developing energy policies and providing energy conservation measures.