Microencapsulation of coco fatty acid mixture for thermal energy storage with phase change material

Thermal energy storage systems provide several alternatives for efficient energy use and energy conservation. Microcapsules of natural coco, fatty acid mixture were prepared to be used as phase change materials for thermal energy storage. The coacervation technique was used for the microencapsulation process. Several alternatives for the capsule wall material were tried. The microcapsules were characterized according to their geometric profiles, phase transition temperatures, mean particle sizes, chemical stabilities, and their thermal cycling. The diameters of microcapsules prepared in this study were about 1 mm. Coco fatty acid mixtures have kept their geometrical profiles even after 50 thermal cycles for melting and freezing operations in temperature range from 22 to 34°C. It was found that gelatin + gum Arabic mixture was the best wall material for microencapsulating coco, fatty acid mixtures. Copyright © 2005 John Wiley & Sons, Ltd

Human body and chromium [Insan vücudu ve krom]

Chromium is an essential trace element that plays a role in carbohydrate metabolism. Chromium is required for optimal insulin activity and maintenance of normal glucose tolarence. Chromium deficiency is associated with elevated blood glucose and decreased high density lipoprotein (HDL) and insulin levels. If chromium intakes adequately from diet it protects people from two important diseases (cardiovascular diseases and diabetes mellitus) that develop due to chromium deficiency. Essential trace elements play a key role in enzyme systems also they have lots of roles that include are in organisation of winter structures such as mitochondrium and ribozome and neural transmission activity of enzymes and membran transport. They have function about protection and construction of protein and nucleic acids and stabilization of ribozomal structures. Inadequacy of these elements in serum and tissues cause decreasing an activation of metabolic events that directed by enzymes. The absorbtion of chromium was greatest in the jejenum followed by the duedenum and ileum by diffusion. Chromium primarily binds to the beta globulin following absorbtion only small amounts of chromium were bound to albumin gama globulin alfa-1 and alfa-2 globulin. It mainly excreted through the kidneys but small amounts of chromium are lost in hair sweat and bile and it can not be reabsorbed by the kidney. Adequate daily dietary intake for chromium in adults aprroximately 50-100 mcg/dl analyzing of chromium is difficult due to its low concentrations in biological materials. Such low consecrations restrict the techniques for chromium analysis to atomic absorption spectrometry graphite furnace mass spectrometry and neutron activation analyse. Trivalent chromium (+3) has a low order of toxicity becomes only at extremely high amounts, however hemalent chromium is extremely toxic. Chromium is vitally essential trace element for maintenance of normal glocose tolerance

Utilization of phase change materials in solar domestic hot water systems

Thermal energy storage systems which keep warm and cold water separated by means of gravitational stratification have been found to be attractive in low and medium temperature thermal storage applications due to their simplicity and low cost. This effect is known as thermal stratification, and has been studied experimentally thoughtfully. This system stores sensible heat in water for short term applications. Adding PCM (phase change material) modules at the top of the water tank would give the system a higher storage density and compensate heat loss in the top layer because of the latent heat of PCM. Tests were performed under real operating conditions in a complete solar heating system that was constructed at the University of Lleida, Spain. In this work, new PCM-graphite compounds with optimized thermal properties were used, such as 80:20 weight percent ratio mixtures of paraffin and stearic acid (PS), paraffin and palmitic acid (PP), and stearic acid and myristic acid (SM). The solar domestic hot water (SDHW) tank used in the experiments had a 150 L water capacity. Three modules with a cylindrical geometry with an outer diameter of 0.176 m and a height of 0.315 m were used. In the cooling experiments, the average tank water temperature dropped below the PCM melting temperature range in about 6-12 h. During reheating experiments, the PCM could increase the temperature of 14-36 L of water at the upper part of the SDHW tank by 3-4 °C. This effect took place in 10-15 min. It can be concluded that PS gave the best results for thermal performance enhancement of the SDHW tank (74% efficiency). © 2008 Elsevier Ltd. All rights reserved.Ministry of Education and Science: ENE2005-08256-C02-01/ALTThis study was supported by The Scientific and Technical Research Council of Turkey (TUBITAK) and The Ministry of Education and Science of Spain through the project ENE2005-08256-C02-01/ALT

English version of Social Networks Adoption Scale: A validation study

The purpose of this study is to validate the English version of the Social Networks Adoption Scale developed by Usluel and Mazman (2009). The original scale consists of 21 items and 5 factors that include usefulness, ease of use, social effect, facilitating conditions and community identity. An online sample of 109 Facebook users completed an internet version of the translated the scale from the USA, Germany, Turkey, and Canada. For the scale's structural validity, first and second order confirmatory factor analysis was conducted. Cronbach's Alpha coefficients (0.90) and item total correlations were calculated to investigate reliability of the scale. Through validity study it was proven that English version of the scale was consisted of five factors. But as a result of the second order confirmatory factor analysis, correlation between social influence variable and adoption variable was found to be insignificant. Therefore, two items included in the social influence factor were extracted from scale. The results indicated that the English version of the Social Networks Adoption Scale consisting of 19 items and 5 factors provided valid and reliable measures of social networks adoption. The Social Networks Adoption Scale can provide an insight to educators about the adoption process of international students from different cultures who seek to use Facebook for educational purposes. © 2015 Elsevier Ltd. All rights reserved

Heat transfer enhancement of fatty acids when used as PCMs in thermal energy storage

Phase change materials (PCM) used in latent heat storage systems usually have very low thermal conductivities. This is a major drawback in maintaining the required heat exchange rate between PCM and heat transfer fluid. This paper investigates the enhancement of the heat transfer between PCM and heat transfer fluid, using high thermal conductivity as additives like stainless steel pieces, copper pieces and graphite-PCM composite material. In the experiments, palmitic-lauric acid (80:20) (PL) and stearic-myristic acid (80:20) (SM) were used as PCMs. Test results show that heat transfer enhancement of copper pieces was better at 0.05 L s-1 flow rate compared to 0.025 L s-1. Using copper as an additive increased the heat transfer rate 1.7 times for melting and 3.8 times for freezing when flow rate was 0.050 L s-1. Decreasing the flow rate from 0.050 to 0.025 L s-1, increased the melting times 1.3 times and freezing times 1.8 times, decreasing heat transfer rates accordingly. The best result of heat transfer enhancement was observed for the PCM-graphite composite. However, changing the flow rate did not affect the heat transfer rate when graphite was used as additive. Copyright © 2007 John Wiley & Sons, Ltd

Ground water level influence on thermal response test in Adana, Turkey

For optimum design of borehole thermal energy storage (BTES) and ground sources heat pump (GSHP) applications, determination of underground thermal properties is required. The design and economic feasibility (number and depth of boreholes) of these systems need thermal conductivity of geological structure, ? (W m-1 K-1) and thermal resistance of ground heat exchanger, R (K W-1 m): Thermal properties measured in laboratory experiments do not coincide with data of in situ conditions. Therefore, in situ thermal response test equipment has been developed and used in Canada, England, Germany, Norway, U.K., U.S.A. and Sweden to ensure precise designing of BTES systems. This paper describes the results and evaluations of the Adana continual thermal response test measurements. Copyright © 2007 John Wiley & Sons, Ltd

CO2 mitigation with thermal energy storage

Thermal Energy Storage (TES) provides us with a flexible heating and/or cooling tool to combat global warming through conserving energy while utilising natural renewable energy resources. This paper aims to show how CO2 emissions can be decreased by utilising different TES concepts in Turkey. The first project is for the heating and cooling of a supermarket using Aquifer Thermal Energy Storage (ATES) in Mersin. With a 60% higher Coefficient of Performance (COP), the yearly CO2 emissions reduction contribution of this project is 113 tonnes. The second project concerns ATES for the heating and cooling of a greenhouse in Adana. The greenhouse was used as a ‘solar collector’ and source of energy for the ATES system. No fossil fuels were consumed for heating the greenhouse and cooling was made possible with the ATES system. Energy conservation amounted to 68% and CO2 emissions were reduced by 26 tonnes/year. The third one is a pilot project using TES in microencapsulated phase change materials in a test cabin in Adana with a floor area of 4 m2. By using a 3.5 kg Phase Change Material (PCM) together with insulation panels in the test cabin, 7% cooling energy and 28% heating energy can be conserved. The corresponding CO2 emissions reduction would be 0.5 tonnes/year. © 2009 Inderscience Enterprises Ltd

Chromium levels in healthy and newly diagnosed type 1 diabetic children

PubMedID: 22783884Background: The aim of this study was to compare the chromium levels of plasma (PCL), erythrocyte (ECL) and urine (UCL) in type 1 diabetics and healthy subjects and to review the relation between metabolic parameters. Methods: We evaluated 165 subjects who were: newly diagnosed type 1 diabetics (group 1 [n = 29]); previously diagnosed type 1 diabetics (group 2 [n = 18]); non-diabetic control subjects who were admitted and treated for any reason in hospital (group 3 [n = 21]); and two other groups of control subjects from two schools that have different socioeconomic levels (group 4 [n = 48] and group 5 [n = 49]). Results: PCL in group 1 and group 2 subjects (7.21 1 4.78 and 10.94 1 3.04 mcg/L, respectively) was significantly lower than in all control groups (21.84 1 7.87, 16.11 1 7.44, 17.25 1 8.58 mcg/L, respectively) (P < 0.05). A significant difference in PCL between the group 1 and group 2 subjects was present (7.21 1 4.78 and 10.94 1 3.04, respectively) (P = 0.021). ECL (as tissue chromium) in group 1 and group 2 subjects (13.99 1 11.37 and 19.64 1 12.58, respectively) was significantly lower than in all control groups (28.20 1 7.34.25, 49 1 12.47, 26.37 1 9.77 mcg/L, respectively) (P = 0.05). UCL in group 1 and group 2 subjects (11.44 1 6.88 and 15.68 1 6.75 mcg/L, respectively) was significantly lower than in group 3 subjects (28.83 1 9.37mcg/L) (P < 0.05). There were significant correlations between length, bodyweight and PCL in the group 1 subjects (r = 0.42, P = 0.22 and r = 0.53, P = 0.03, respectively). There was a negative correlation between plasma glucose and UCL, which was not statistically significant in group 2 subjects (r = -0.4, P = 0.061). Conclusion: There was a negative chromium balance in type 1 diabetics. This negative balance may affect the insulin function badly. If this negative balance should be confirmed by recent studies we suggest that chromium supplementation with insulin is necessary for type 1 diabetes. © 2012 The Authors