Investigation of exergy ratios of a solar pond

In this paper, we present an experimental and theoretical investigation for exergetic assessment of a rectangular solar pond (with dimensions of 2 m × 2 m × 1.5 m) at various reference temperatures. The experimental solar pond was designed and built at Cukurova University in Adana, Turkey. The system was filled with salty water to form three zones (namely, Upper Convective Zone (UCZ), Non-Convective Zone (NCZ), and Low Convective Zone (LCZ)) accordingly. A data acquisition device was used to measure the temperatures hourly at various locations in the pond. An exergy model was developed to study the exergetic performance of the pond for its three zones in terms of exergy efficiencies. The lowest and highest reference environment temperatures for various days in the months were considered. The results show that the efficiency ratios of the LCZ are found to be higher than the corresponding the NCZ and also the UCZ. © Springer International Publishing Switzerland 2014

Determination of geothermal fields at kızılcahamam (ankara) using vertical electrical sounding (ves) and spontaneous potential (sp) methods

Abstract Geophysical exploration of geothermal resources deals with measurements on the physical properties of the Earth with two methods. First, the vertical electrical sounding (VES) method which is useful in determining the depth of overburden and depth, structure, and resistivity of flat-lying sedimentary beds and possibly of the basement also if it is not too deep. Furthermore the search for geothermal reservoirs normally involves resistivity surveying, and it is also employed routinely in groundwater exploration, which is of increasing worldwide importance. Second, spontaneous potential (SP) method is applied for determining the possible faults and finding the places with and without the liquid flow in the study area. At the SP graphic is analyzed that the natural voltage in a few measuring points varied between +28mV and —48mV values. At the natural potential, the plus (+) and minus (—) transitions indicate faulting zone. In this work, VES and SP methods at Kızılcahamam (Ankara) geothermal area were used to delineate location of aquifer zones and site wells or estimate properties of the system. Schlumberger electrode arrays were used in the VES measurements at 60 point in the study area. Schlumberger soundings at the study area have been carried out to try and estimate the bedrock resistivity at different depths. The measured quantity at the study area was called apparent resistivity. Interpreting the resistivity data consists of two steps: first, a physical interpretation of the measured data, resulting in a physical model, and second, a geological interpretation of the resulting physical model. The resistivity structure at study area is dominated by two coherent low resistivity layers that underlie most of the field. The shallower layer (<10?m) lies within 300m depth, while the deeper one is at about 900m depth. Resistivity of rocks depends on porosity, saturation, content of clay, and resistivity of pore water. As a result of all these studies, geothermal anomalies having low resistivity values at the five different VES points have been identified. For geothermal drilling of the suggested VES, points constitute the appropriate fields. © Springer International Publishing Switzerland 2015

Investigation of hydrogen production performance of chlor-alkali cell integrated into a power generation system based on geothermal resources

In present study, hydrogen production performance of chlor-alkali cell integrated into a power generation system based on geothermal resource is studied. The basic elements of the novel system are a separator, a steam power turbine, an organic Rankine cycle (ORC), an air cooled condenser, a saturated NaCl solution reservoir tank and a chlor-alkali cell. To enhance the performance of the cell, the saturated NaCl solution is heated by the waste heat from the ORC. So, this integrated system generates significant amount of electricity for the city grid and also yields three main products those are hydrogen, chlorine and sodium hydroxide. According to the parametric study, when the temperature of a geothermal resource varies from 140 to 155 °C, the electrical power generation increases from nearly 2.5 MW to 3.9 MW and hydrogen production increases from 10.5 to 21.1 kg-h. Thus, when the geothermal resource temperature of 155 °C, the energy efficiency of the system is 6.2% and the exergetic efficiency is 22.4%. As a result, the geothermal energy potential plays a key role on the integrated system performance and the hydrogen production rate. © 2018 Hydrogen Energy Publications LLCFEF2013YL42, FDK-2017-7005The authors acknowledge the support provided by University of Cukurova in Turkey (Grant Nos: FEF2013YL42 , FDK-2017-7005 )

Assessment of electricity and hydrogen production performance of evacuated tube solar collectors

In this work, a unified renewable energy system has designed to assess the electricity and hydrogen production. This system consists of the evacuated tube solar collectors (ETSCs) which have the total surface area of 300 m2, a salt gradient solar pond (SGSP) which has the surface area of 217 m2, an Organic Rankine Cycle (ORC) and an electrolysis system. The stored heat in the heat storage zone (HSZ) transferred to the input water of the ETSCs by means of an exchanger and thereby ETSCs increase the temperature of preheated water to higher level as much as possible that primarily affects the performance of the ORC. The balance equations of the designed system were written and analyzed by utilizing the Engineering Equations Solver (EES) software. Hence, the energy and exergy efficiencies of the overall system were calculated as to be 5.92% and 18.21%, respectively. It was also found that hydrogen generation of the system can reach up to ratio 3204 g/day. © 2018 Hydrogen Energy Publications LL

Determination of a geothermal energy field with audio-magnetotelluric (AMT) data at the south of Manisa, Turkey

In this study, we present an investigation of the geothermal energy field and its energy potential at the south of Manisa in Turkey. The resistivities of the geothermal energy field have a key role in determining geothermal energy reservoir and potential in the field. This work focuses on low-resistivity zones in order to determine the geometry and extension of the geothermal system by using the Audio-Magnetotelluric (AMT) method that is to image rock units below the shallow subsurface and determine deeper structure that might represent permeability in a geothermal system. Therefore, AMT stations were arranged with an interval of about 1 km array and its measurements were carried out at 40 sites, which were located on approximately 9.5 km long profiles at the south of Manisa. The resistivity model was obtained from the 2D inversion of AMT data to show subsurface specific conductive and resistive features in the field. As a result, two geothermal anomalies were defined at the study area by using AMT data and the resistivity of soft rock is found generally quite low (<200 ?m), however, hard rock displayed higher resistivity. But, low resistivities can also evaluate in the fault zones because of water content and rock softening. © Springer International Publishing Switzerland 2014

Reply to "Erroneous equations used for energy and exergy analysis of a solar pond" by M. Khalilian

WOS: 000377726300042

Investigation energy, exergy and electricity production performance of an integrated system based on a low-temperature geothermal resource and solar energy

In this work, energy, exergy and electricity generation performance of an integrated system was conceptually investigated by using Engineering Equation Solver (EES)under 200–1000 W/m2 solar irradiation interval. The system comprises evacuated tube solar collectors (EVTSCs)with the surface area of 100 m2, an organic Rankine cycle (ORC)and a low-grade geothermal resource. The EVTSCs were used to enhance the temperature of the low-grade water coming from the geothermal source. The calculations were carried out for three geothermal sources in Kula (63 °C), Saraycık (74 °C)and Turgutlu (86 °C), respectively. N-hexane, n-pentane and n-butane were selected as a working fluid in the ORC. It was determined that the selection of the working fluid affected the performance of the ORC. And also, the waste heat is extracted from the ORC were used efficiently for space heating. As a result, the overall energy and exergy efficiencies of the system and power generation of the ORC were seriously affected by enhancing the water temperature of the geothermal resources by EVTSCs. The maximum overall energy and exergy efficiencies of the system were calculated as to be 6.92% and 21.06% by using n-butane for the source in Turgutlu, respectively. The minimum overall energy and exergy efficiencies of the system were calculated as 0.32% and 2.19% by using n-hexane for the source in Kula, respectively. The maximum and minimum generated electricity were calculated as to be 19.46 kW and 0.6168 kW for the sources in Turgutlu and Kula, respectively. It was seen that the best performance of the system was found for n-butane compared to n-pentane and n-hexane. © 2019 Elsevier Lt

Performance analysis of a solar pond

In this contribution, we develop a theoretical solar pond in different geometries for the Adiyaman region in Turkey and analyze its performance assessment through energy efficiency. Some key parameters such as surface area, depth, densities of the layers, the thicknesses of the inner zones and the insulations of the walls to assess the solar pond are considered. In the parametric studies, the dimensions of the zones (e.g., upper convective zone, non-convective zone, and lowconvective zone) are varied to investigate their effects. Although the density and temperature gradient of the inner zones are considered similar to each other, the energy efficiencies of the storage zones become different due to varying dimensions of the pond. The shading area decreases by increasing the surface area of the inner zones. The amount of incoming solar energy to the upper surface is increased with the size of the solar pond. The energy efficiency of the solar pond is determined to be maximum (31.76 %) for case4a, and to be minimum (16.80 %) for case1b in August. As a result, through careful determination of the dimensions and insulation parameters, incoming solar radiation reaching the storage zone increases the energy efficiency of the solar pond. © Springer International Publishing Switzerland 2014

A preface to the special issue section on “The Second International Hydrogen Technologies Congress (IHTEC 2017), 15–18 March 2017, Adana, Turkey”

[No abstract available

Exergetic performance analysis of a solar pond

In this paper we present an experimental and theoretical investigation of the exergetic performance of a solar pond (with a surface area of 4 m2 and a depth of 1.5 m) which was built at Cukurova University in Adana, Turkey. The system was filled with salty water to form three zones (e.g., upper convective, non-convective and heat storage) accordingly. A data acquisition device was used to measure and record the temperatures hourly at various locations in the pond (distributed vertically within and at the bottom of the pond, and horizontally and vertically within the insulated side-walls). An exergy model is developed to study the exergetic performance of the pond and its three zones in terms of exergy efficiencies which are then compared with the corresponding energy efficiencies. The reference environment temperature is specified for exergy analysis as the average representative temperature of each month of the year (for example, it is taken as an average temperature of 28 °C for August). Thus, the highest energy and exergy efficiencies are found for August to be: 4.22% and 3.02% for the upper convective zone, 13.80% and 12.64% for the non-convective zone, and 28.11% and 27.45% for the heat storage zone, respectively. © 2007 Elsevier Masson SAS. All rights reserved.Natural Sciences and Engineering Research Council of CanadaThe authors acknowledge the support provided by Cukurova University in Turkey, and the Natural Sciences and Engineering Research Council of Canada in Canada