Arif Hepbasli

Energy and exergy analysis of a ground source (geothermal) heat pump system

Ground source heat pumps (GSHPs), often referred to as geothermal heat pumps (GHPs), offer an attractive option for heating and cooling residential and commercial buildings owing to their higher energy efficiency compared with conventional systems. GSHPs have been used for four years in the Turkish market, although they have been in use for more years in developed countries. The purpose of this study is to present an energy and exergy analysis of a GSHP system with a 50 m vertical 1.25 in. nominal diameter U-bend ground heat exchanger. This system was applied to a 65 m2 room in the Solar Energy Institute, Ege University, Izmir, for the first time at the university level in Turkey. The Institute, built in 1986, has a livable floor area of 3000 m2 and uses passive solar techniques. The heating and cooling loads of the room studied were 3.8 and 4.2 kW at design conditions, respectively. The system was commissioned in May 2000, and performance tests have been conducted since then. The exergy transports between the components and the consumptions in each of the components of the GSHP system were determined for the average measured parameters obtained from the experimental results in February 2001. The exergy diagram (the Grassmann diagram) was also presented for the GSHP system studied to give quantitative information regarding the proportion of the exergy input that is dissipated in the various system components.

Experimental study of a closed loop vertical ground source heat pump system

Ground source heat pumps (GSHPs), also known as geothermal heat pumps, are a promising new technology that has been used for the last three years in the Turkish market. The main objective of the present study, which was performed for the first time in Turkey at the university level, is to investigate the performance characteristics of a GSHP system with a 50 m vertical 1 1 in. nominal diameter U-bend ground heat exchanger. This system was installed in a 65 m 2 room in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22 � C, 1226 degree days heating, base: 18 � C), Turkey. The Institute, built in 1986, has a livable floor area of 3000 m 2 and uses passive solar techniques. The heating and cooling loads of the room were 3.8 and 4.2 kW at design conditions, respectively. The system was commissioned in May 2000 and performance tests have been conducted since then. Based upon the measurements made in the heating mode, the heat extraction rate from the soil, with an average thermal diffusivity of 0.00375 m 2 /h, was found to be, on average, 11 W/m of bore depth, while the required borehole length in meter per kW of heating capacity was obtained as 14.7. The entering water temperature to the unit ranged from 5.5 to 13.2 � C, with an average value of 8 � C. The heating coefficient of performance of the heat pump and the whole system was extremely low when compared to other heat pumps operating under conditions at or near design values. The primary reasons for this were discussed in detail, and the potential for performance improvements was also suggested. � 2002 Elsevier Science Ltd. All rights reserved.

Development of energy efficiency and management implementation in the Turkish industrial sector

Abstract The importance of energy efficiency was first realized following the two oil crises of the 1970s. The world has trimmed its energy budget by utilizing higher efficiencies, while still growing economically, and has realized the importance of protecting the environment. The main objective of this paper is to investigate the development of industrial energy efficiency and management studies in Turkey up until August 2001. In Turkey, the demand for energy efficiency started in the 1980s. Planned energy conservation activities were first implemented in 1981 by the General Directorate of Electrical Power Resources Survey Administration (called EIE in Turkey). Since 1981, EIE has been conducting these activities. In the beginning of the year 1993, the National Energy Conservation Center (NECC) was established within the body of EIE. EIE/NECC investigated the nationwide potential for energy conservation. The study concluded that the Turkish industrial sector has an annual energy saving potential of approximately 30%. After this study, a regulation on industrial energy efficiency was issued in 1995, followed by two announcements related to designing energy management courses and performing energy audits in 1996 and 1998, respectively. By means of these regulations, the Turkish industrial sector has significantly accelerated efforts in implementing energy efficiency and management studies in the country.

Present status and potential of renewable energy sources in Turkey

The effects on global and environmental air quality of pollutants released into the atmosphere from fossil fuels in power plants provide strong arguments for the development of renewable energy resources. In this regard, the objective of this study is to investigate the present status, the technical potentials, and the regional distribution of renewable energy resources in Turkey. The following resources were taken into consideration: solar energy, wind energy, hydro energy, geothermal energy, biomass, and wave energy. The present study shows that Turkey has extensive renewable energy resources that can be developed as a significant source of energy.The effects on global and environmental air quality of pollutants released into the atmosphere from fossil fuels in power plants provide strong arguments for the development of renewable energy resources. In this regard, the objective of this study is to investigate the present status, the technical potentials, and the regional distribution of renewable energy resources in Turkey. The following resources were taken into consideration: solar energy, wind energy, hydro energy, geothermal energy, biomass, and wave energy. The present study shows that Turkey has extensive renewable energy resources that can be developed as a significant source of energy.

Energy Demand Estimation Based on Two-Different Genetic Algorithm Approaches

Energy modeling is a subject of widespread current interest among engineers and scientists concerned with problems of energy production and consumption. Energy planning is not possible without a reasonable knowledge of past and present energy consumption and likely future demands. In this study, two forms of the energy demand equations are developed in order to improve energy demand estimation efficiency for future projections based on the genetic algorithm (GA) notion. The genetic algorithm energy demand (GAEDM) model is used to estimate Turkeys future energy demand based on gross domestic product, population, import, and export figures. Both equations proposed here are non-linear, of which one is exponential and the other is quadratic. The quadratic form of the GAEDM model provided a slightly better fit solution to the observed data and can be used with a high correlation coefficient for Turkeys future energy projections. It is expected that this study will be helpful in developing highly applicable and productive planning for energy policies.

Geothermal district heating applications in Turkey: a case study of Izmir–Balcova

Abstract Turkey is located on the Mediterranean sector of the Alpine–Himalayan Tectonic Belt and is among the first seven countries in abundance of geothermal resources around the world. However, the share of its potential used is only about 2%. This means that considerable studies on geothermal energy could be conducted in order to increase the energy supply and to reduce atmospheric pollution in Turkey. The main objective in doing the present study is twofold, namely: (a) to overview the status and future aspects of geothermal district heating applications in Turkey and (b) to present the Izmir–Balcova geothermal district heating system, which is one example of the high temperature district heating applications in Turkey. The first geothermal heating application was applied in 1981 to the Izmir–Balcova thermal facilities, where the downhole heat exchanger was also used for the first time. Besides this, the first city based geothermal district heating system has been operated in Balikesir–Gonen since 1987. Recently, the total installed capacity has reached 820 MWt for direct use. An annual average growth of 23% of the residences connected to geothermal district heating systems has been achieved since 1983 in the country, representing a decrease of 5% in the last three years. Present applications have shown that in Turkey, geothermal energy is much cheaper than the other energy sources, like fossil fuels, and can make a significant contribution towards reducing the emission of greenhouse gases.

Estimation of Wind Power Potential Using Weibull Distribution

The main objective of the present study is to estimate wind power potential using the two Weibull parameters of the wind speed distribution function, the shape parameter k (dimensionless) and the scale parameter c (m/s). In this regard, a methodology that uses three various techniques (maximum likelihood, least squares, and method of moments) for estimating the Weibull parameters was given first. The methodology was then applied to a region in Turkey. Finally, the parameter techniques were compared to Monte-Carlo simulation in different sample sizes, and the best parameter estimation techniques belonging to the sample sizes were also determined.

Solar Radiation Models. Part 2: Comparison and Developing New Models

Solar engineers, architects, agriculturists, and hydrologists in many applications of solar energy require a reasonably accurate knowledge about the availability of solar resources at any place. For this purpose, in the past, several empirical models have been developed in order to estimate the solar radiation around the world. The main objective of the present study is twofold, namely: (1) to compare some existing models used for estimating the monthly average daily global solar radiation on a horizontal surface (H) for Turkeys big cities such as Istanbul, Ankara and Izmir, which cover approximately 30% of the population of Turkey, and (2) to develop some empirical models for these cities. Experimental data for Izmir were measured in the Solar-Meteorological Station of the Solar Energy Institute at Ege University. The present models were then compared with the 25 models, of which 12 were given in Part 1 of this study (defined as national models), while the remainder (called international models), presented here, and used for calculating H. The main percentage error (MPE), the root mean square error (RMSE), the main bias error (MBE) and the t-statistic (t-stat) methods were used for evaluating the performance of the models studied. It may be concluded that the present models predict the values of H for the three big cities better than other available models.

Current Status of Geothermal Energy Applications in Turkey

Turkey is located on the Mediterranean sector of the Alpine-Himalayan Tectonic Belt and has a place among the first 7 countries due to the abundance of geothermal resources around the world. The share of its potential used is, however, only about 2–3%. This means that considerable studies on geothermal energy could be conducted in order to increase energy supply and to reduce atmospheric pollution in Turkey. The main objective in doing the present study is to provide an overview of the current status of geothermal energy use in Turkey. The first geothermal heating application was applied in 1981 to Izmir-Balcova thermal facilities, while the first city-based geothermal district heating system has been operated in Balikesir-Gonen since 1987. Recently, the total installed capacity has reached 820 MWt and 20.4 MWe for direct use and power generation, respectively. An annual average of 23% growth of residence connections to geothermal district heating systems has been achieved since 1983 in the country, representing a decrease of 5% in the last 3 years. The total area of the geothermal heated greenhouses exceeded over 50 ha with a heating capacity of 112.5 MWt. Geothermal heat pumps (GHPs) have also been put on the Turkish market since 1998, and there are no Turkish GHP manufacturers yet. It may be concluded that geothermal energy has had, or will have, a significant and increasing role in dictating the energy strategies for Turkey.

A Comparative Study on Exergetic Performance Assessment for Drying of Broccoli Florets in Three Different Drying Systems

This article deals with the exergy analysis and evaluation of broccoli in three different drying systems. The effects of drying air temperature on the exergy destruction, exergy efficiency, and exergetic improvement potential of the drying process were investigated. The exergy destruction rate for the drying chamber increased with the rise in the drying air temperature at 1.5 m/s, both in the tray and the heat pump dryer. The highest exergy efficiency value was obtained as 90.86% in the fluid bed dryer in comparison to the other two drying systems and the improvement potential rate was the highest in the heat pump dryer during drying of broccoli at the drying air temperature of 45°C and the drying air velocity of 1.0 m/s.