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- VI ı - SUMMARY The attractiveness of solar energy as a renewable source of energy available world Wide is self-evident in these times of world energy shortage. But the harnessing of solar energy on a large scale is confronted with two intrinsic difficulties arising from two fundemental characteristics of solar radiation: Low energy-density and irregularity. Low energy-density means that collecting solar energy in commercial quantities would require a collecting apparatus of very large dimensions. Such large collector systems in volve large investments both in money and materials and ex plain why even the simplest solar collectors are not viable in an era of cheaper fuels. Further problems arising from the large areas of collection include: a) Bringing the energy collected over a large area to a central point of use: Processes resulting in considerable losses of energy enroute besides their initial costs. b) Keeping such large areas clean. * The solar radiation reaching any point on earth's sur face exhibits a regular cylic character defined by sun-earth geometry plus superimposed irregularity caused by atmospheric conditions. In the vast majority of solar energy applications the time pattern of energy demand is not the same as the time pattern of insolation. Some form of energy storage or an auxiliary energy supply is needed for such instances when collected s^lar energy cannot meet demand. Alternatively excess collected solar energy must be `dumped` when it?vııı- exceeds demand. Thus, for example, harnessing solar energy for heating buildings in winter when the solar energy is at a minimum, would be greatly facilitated if a viable long term storage system that could exploit summer sun shine for winter use was available. There has thus been a very strong incentive to produce a solar collector system that would be large both in area and built-in energy storage capability. The non-convecting solar pond (The solar salt-gradient pond) is the product of an effort directed towards this end. Before describing a solar pond, we must review briefly what happens in an ordinary pond e.g a garden pond. Part of the sunlight incident on the pond is absorbed in the water, and part is absorbed on the bottom of the pond. The latter absorption leads to the heating of the water in the lower part of the pond. Being warmer, and hence of lesser density than the cooler water above it, the heated water begins to rise and sets up convection currents that eventually lead to the dissipation of the absorbed heat from the surface of the pond. A solar pond is designed to suppress this convection and retain the heat at the bottom of the pond. The solar pond is a solar collector and seasonal heat storage device whose structure is shown schematically in Figure 1.1. The solar salt gradient pond is a still body of water consisting of two convective layers and an insulating layer (non-convective zone) in between. The upper convective layer consists almost wholly of fresh water. The bottom con vective layer is a concentrated salt solution. It is covered fc^`- ıx - by the insulating layer which has a salt gradient increasing with depth. Since the hotter but saltier water at the bottom of, the gradient will be denser than the colder and less salty water above it, there will be no convection in the insulating layer when heat is absorbed on the bottom, if the salt gradient of the insulating layer is large enough. Also, as water is transparent to visible light but opeque to infrared radiation, the heat which reaches the darkened bottom in the form öf sunlight is absorbed there, and can escape only by conduction. Accordingly the pond is always insulated at the bottom to prevent heat loses there. Because the thermal con ductivity of water is moderately low and the insulating layer is thick enough, heat dissapation through the insulating layer is very slow. »This makes the solar pond not only a thermal collector but also a seasonal heat storage device. Storage capacity is increased by increasing the thickness of the hot convective bottom layer. The growth of this layer is related to the intensity of the incident solar radiation and the salt concentration difference between the surface and the bottom of the pond. '? Although, in the case of increased radiation inten sity, the growth of the bottom convective zone leads to an increase in the amount of energy to be stored, this may also lead to a decrease in the thickness of the insulating layer and hence the starting of a convection current. When convec tion starts in the insulating layer which becomes unstable, a continuous loss of heat from the system occurs. To prevent convection in the insulating layer the initial salt concent ration difference between the surface and the bottom of the- x - ? pond must be calculated beforehand for the verification of stability criteria of the insulating layer. Research done on available literature on solar ponds has revealed that: a) The amount of research conducted on the absorption of solar energy in concentrated salt water solutions is scarce, b) Almost no stability criteria exists on the insulat ing layer ( Non-con vective zone) of solar ponds. In this study the derivation and experimental proof of the stability criteria of the insulating layer has been aimed at rather than the analytical solution of temperature and concentration distributions in solar ponds. However, time- dependent temperature and concentration distributions at varying salt concentrations have also been experimentally investigated as shown in Figures 3.7 - 3.21. In the theoretical part of the study the absorption of solar radiation in salt water has been examined and a one dimensional mathematical model of a solar pond has been worked out. Although some empirical formulas for absorption and distribution of solar radiation in salt water have been presented by Bryant and Colbeck, RabT and Nielsen and others { 4 } { 1 4 } { 2 9 } { 3 5 }, these analytical forms do not conform with Schmidt's data{34}, as can be seen in Figure 2.2. Therefore, in this study, a formula to conform with Schmidt's data, which is shown in Table 2.1, has been developed-by prior knowledge and proof that the use of an inorganic salt, when added to water, does not radically affect optical properties- XT of water: where: Y(xi)= 2 S_ exp(-K, x')+ z n exp(-K x') J t İl U O M i lit bm O n=l n m=l li! x 3* n K ı K u Vertical coordinate from the water surface. Percentage of the incident radiation flux at any depth x~. Fraction of long-wave portion of solar spectrum. Fraction of visible portion of solar spectrum. Extinction coefficient for long-wave solar radia tion absorbed by water. Extinction coefficient for short-wave solar radia tion absorbed by water. The values of $. Ku. nm and KSm are given at Tables -, n un m 3m 3 2.2 and 2.3. Additionally stability criteria of the insulat ing layer were obtained by the application of the Gal erkine Method-with only the transfer of heat by convection under consideration-to the cases of absorption and non-absorption in the pond. The equation, Pr R_(l + A ) £ J^-r R T r Pr+1 for the absorption case, and the equation RT, Pr R Pr+1 c for the non-absorption case were derived. The second equation was found to agree well with the study of Veronis{45}. In these two equations:- xn - RT Thermal Rayleigh number.: = Absorption effect of solar energy in water Pr = Prandtl number R = Salinity Rayleigh number In the experimental part of the study a 290x190x240 mm insulated laboratory pond which was subjected to a constant incident heat-lamp radiation was used (1. and 2 in Figure 3.1). An 290x190x2 mm copper-oxide plated aluminium plate was pla ced at the bottom of the pond for the purpose of providing a selective' surface. The pond was filled with one layer of pure water and four layers of potassium Nitrate (KNOo) solu tions (Pr=3) with concentrations ranging from o `to 10, 0 to 60, 0 to 100, 0 to 150 and 0 to 200 kg/m3. In all experiments the bottom layer, consisting of the most concentrated solu tion, was filled first and the top layer, being of pure water was filled last. Time-dependend temperature profiles were measured by two vertically movable copper-constantant thermocouples (5 in Figure 3.1). The incoming heat-lamp radiation was measured to 2 be 1200 W/'m at the surface of the pond through the use of an Epply Black solarimeter. The time-dependend concentration profiles were obtained through the use of a probe which con tained 13 pairs of gold plated sensors (Figure 3.5). The func tion of the probe was to measure the electrical conductivity of salt water at different depths. In the experiments conducted with 0. to 10 and 0 to 60 kg/m` concentrations, the stability of the system was observ ed to deteriorate. Also, the data obtained from these experi-- XI 11 ` men ts` when applied to the stability criteria of the systems, yielded identical results (Figure 4.1), However when the experiments were conducted with 0 to 100, 0 to 150 and 0 to 200 kg/m, concentrations the stability of the system (insu lating layer) was observed to be steady. Again, when the data obtained from these experiments were applied to the stability criteria of the system, identical results were obtained (Figure 4.1 ). An examination of Figure 4.1 will show that the ther mal Rayleigh numbers calculated from the data of experiments conducted with concentrations of 0 to 100, 0 to 150 and 0 to 3 200 kg/m are smaller than the salinity Rayleigh numbers 10 8 (Rr * 10, RT * 10 ) and that the consequent results fall within the stable region. On the otherhand the thermal Ray- leigh numbers calculated from the data of experiments conduct- I,8 3 ed with concentrations of 0 to 10 and 0 to 60 kg/m are greater than the salinity Rayleigh numbers (Rr - 10 10 RT ~ 10 ) and the consequent results fall within the unstable region. The convective stability problem in solar ponds was experimentally examined by Styris, Leshuk and others with methods showing a close similarity to the ones used in this study{3}{16}{22}{27}{29}{39}. As seen in Figure 4.1, the results achieved by the application of the data established in experiments conducted by the above named researchers to the stability criteria for the case of absorption of radia tion display a complete agreement with the results obtained in this study.-XIV ~ To recapitulate, for a salt gradient solar pond com posed of water and inorganic salts to store the solar energy it absorbs, an insulating layer (Nonconvecting zone) must be present in this pond, The presence of this insulating layer is dependent on the establishment of a minimum of 100 kg/m initial salt concentration difference between the surface and the bottom of the pond. In the design of the artifical solar ponds the initial concentration difference verifying the stabi lity criteria can be derived from Figures 3.26, 3.27, and 4.1. ] 1 1. ?-. ÖZET Dünyada enerji tüketimi, uygarlık düzeyinin yükselme siyle hızla artarken, insani iğin.en güncel ve başta gelen so runu; artan enerji gereksinmelerini karşılayabilecek yeni enerji kaynaklarının bulunmasıdır. Güneş enerjisi; teknolojisinin hızla gelişmesi, çok çeşitli uygulama alanları bulması ve günlük yaşantımıza konut ısıtılmasından elektrik üretimine kadar değişik alanlarda girmesiyle yeni enerji kaynakları arasında en ön sırayı al maktadır. Şu andaki en önemli sorun, sürekli ve yoğun bir enerji türü olmaması nedeniyle uzun süre depolanmayı gerek- tirmesidir. Bu nedenle maliyeti düşük ve verimi yüksek topla yıcı ve depolayıcı.teknolojinin geliştirilmesine gerek var dır. Günümüzde güneş enerjisinin toplanması ve depolanması bakımından geliştirilmiş sistemler arasında en uygun olanı, yüzeyine gelen güneş enerjisinin %20-30'unu depolayabilen gü neş havuzlarıdır. Literatürden ve sunulan bu çalışmadaki de neylerden, içindeki akışkan yoğunluğunun derinlikte arttığı derişiklik gracjyenli bir güneş havuzu uygun olarak tasarımm- lanırsa, yüzeyden dibe doğru üst taşımmlı, ara taşınımsız ve alt taşımmlı olmak üzere üç karakteristik bölgeden oluşabi leceği görülmüştür. Bu tip havuzların veriminin arttırılabilmesi, güneş havuzunun dibinde soğurulan güneş enerjisinin taşınım yoluyla- iv - y-izeyden kaybına engel olan ve yalıtıcı gibi vazife gören ara taşınmışız bölge içinde molekülsel düşey harekete mani olacak derişiklik gradyamnın oluşturulması ile mümkündür. Literatür araştırmalarımız sonucu; güneş havuzlarının temel maddesi olan su içinde güneş enerjisinin soğurulması ve havuzlardaki kararlılık problemleri hakkında çok az sayıda çalışmaya rastlanmış ise de özellikle güneş havuzlarının ta şınmışız ara bölgesinde geçerli olan kararlılık koşulları kriteri eriyle ilgili bir çalışmaya rastl anı lamamı ştır. Sunulan çalışmanın teorik bölümünde ilk olarak, güneş enerjisi spektrumunun su içindeki dağılımına ait eksponansi- yel bir bağıntı önerilmiştir. Bu bağıntının, deneysel bulgu lar ile iyi bir uyum içinde olduğu görül müştür{34}. Teorik bölümün ikinci kısmında ise güneş enerjisinin tuzlu su içinde soğurulması incelenmiş ve bir boyutlu güneş havuzunun matema tik modeli çıkarılmıştır. Elde edilen genel enerji denklemi, probleme ait başlangıç ve sınır koşulları için, sonlu farklar metodu ile bilgisayar yardımıyla çözülmüştür. Teorik bölümde üçüncü olarak, kararlı halde taşınım! ı iki bölge arasında ısı taşınımına engel olan ara taşınmışız bölgenin kararlılık ko şulları Galerkin yöntemi kullanılarak elde edilmiştir. Taşı nmışız ara bölgede güneş ışınımının; soğurulmadığı durumda kararlılık koşulu için: RT'< [Pr/(Pr-l.î]Rc soğurulduğu durumda kararlılık koşulu için,- v- - RT(1+A ) < [Pr/(Pr+l[[Rr ı r ^* bağıntılarının geçerli olduğu bulunmuştur. Çalışmanın deneysel bölümü, Potasyum Nitrat (KNC^» Pr=3, Le=100) tuzunun çeşitli derişiklikteki çözeltileri ile doldurulmuş laboratuvar havuzunun, devamlı bir ışınıma ve pe riyodik olarak ışınım ve karanlığa maruz bırakılması şeklinde gerçekleştirilmiştir. Başlangıçta havuz yüzeyi ile dibi ara- 3 sında tesis edilen 10 ve 60 kg/m lük derişiklik farkları, zaman ve derinlikle artan sıcaklığın ara taşınımsız bölgede başlattığı taşınım hareketini engelliyememiş ve kararlılık 3 bozulmuştur. Buna karşılık, 100, 150 ve 200 kg/m lük başlan gıç derişiklik farkları için yapılan deneylerde ise ara taşı nımsız bölgenin kararlılığı bozulmamış ve alt taşınımlı böl gede enerji depolanmıştır. Bu sonuçlar, deneylerden elde edi len verilerin kararlılık koşullarında kullanılmasıyla da elde edilmiştir. Taşınımsız ara bölgenin kararlılığının bozulmadı - ğı derişiklik farklarında (en az 100 kg/m ), derişiklik Ray- leigh sayısı R 'nin mertebesi yaklaşık olarak 10, ısıl Ray- o leigh sayısı Ry'nin mertebesi ise 10 olarak, bulunmuştur. Sunulan çalışmaya en yakın şekliyle deneysel olarak yapılan konvektif stabilite çalışmalarından elde edilen bul gular, bu çalışmadaki deneysel ve teorik sonuçlarla karşılaş tırıldığında, uyum içinde oldukları görülmüştür.- vı -. Bunlara ilaveten, yapay havuzların tasarımında, yüzey le dip arasında tesis edilerek, ara taşınmışız bölgenin ka rarlılık koşullarını sağlayacak başlangıç derişiklik farkının yaklaşık olarak tespit edilebilmesi için gerekli diyagramlar hazırlanmıştır. 137

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VII ABSTRACT PhD. Thesis THE USE OF A SOLAR ENERGY SYSTEM WITH CONICAL CONCENTRATOR IN DRYING Inci TURK TO?RUL Fırat University Graduate School of Natural and Applied Sciences Department of Chemical Engineering 2001, Sayfa: 264 Recently solar energy has become a research field on which intensive studies has been undertaken, since its superiority of not only a new and renewable energy source but also presenting none of environmentally polluting wastes and not requiring complicated technology. The heating of buildings, drying of industrial products and production of electrical energy are examples of solar energy applications. Solar concentrators should be used in the high temperature applications. Although flat-plate collectors use much more solar radiation per collector aperture than concentrating collectors do, higher temperatures may result in concentrating collectors. Turkey has a great solar energy potential and presently, fiat-plate collectors have been widely used in applications under 90°C temperatures. Today, many studies are being carried on developing solar energy application technologies. But, in the case of air heating, absent of systems which are capable of reaching high temperatures have been seen a lacking potential research area.VIII In order to attain high temperatures, in this work, an air heater with a conical concentrator has been designed, constructed and its performance has been tested with respect to main system parameters. A cylindrical absorber was mounted in the centre of reflector which is designed differently from the systems being used up to now and lias a conical shape. By acquiring the conical reflector to track the sun from sunrise to sunset, the solar radiation has been supplied to be reflected vertically on the absorber in all the day times. The performance of this newly designed air heater with conical concentrator has been examined at natural and forced flow conditions. The best inclination angle for the collector placed at three different angles have been determined. Among the settings of 28.4°, 33.4°and 38.4° angles, the highest temperature and efficiency values were obtained at 28.4° inclination angle. Although the system reached very high temperatures (~155°C) when it was run at natural convection conditions, its efficiency was limited about 11% due to lower air flow rates. In the forced-flow tests carried at five different air flow rates between 30- 70 kg/hr, however, the highest temperatures were obtained at 30 kg/hr, the lowest flow rate applied, whereas the highest efficiencies (i.e. 50 %) were obtained at 70 kg/ hr, the highest flow rate. Selective absorber was used to increase the efficiency of the air heater with conical concentrator. With the use of selective-surface absorber which was obtained by colouring nickel-plated copper surface with black chromium paint, the natural and forced convection efficiencies of the system were increased by 3.6 % and 6%, respectively. Another method used widely to enhance the efficiency of air heaters is to increase heat transfer area by placing packing materials into the air flow channel. For this purpose, aluminium wire mesh folded in various numbers were placed in the air channel under the absorber so as to contact with its inner surface. It was seen that natural convection efficiency decreased, but forced convection efficiency of the system increased usually when wire mesh packing of 6, 10 and 14 folding numbers were used. In the case of air passing through the system by natural convection the efficiencies ofIX the system decreased by 31.5-36.2 % depending on the folding numbers because, packing placed into the flow channel has presented additional resistance to the motion of air through the channel. The efficiency in forced connection, however, increased to 60-80 % depending on folding numbers, as the heat transfer surface to the air flowing inside the absorber increased by use of packing. The heat transfer coefficient increased up to 10 times by using folded packing. The efficiency of system increased up to 85%, which represented improvement by 68%, when selective absorber and packing material were used together. Absorber surface obtained by covering the black-painted absorber with an aluminium wire mesh coated with black paint was also used to increase the efficiency of air heater with conical concentrator. It was observed that absorber surface so roughened artificially, caused the efficiency of the system to decrease in both natural and forced convection flow conditions. Contrary to the expectations that the roughened surface would absorb much more solar energy and increased the efficiency, it was seen that the heat absorbed by this surface could not effectively transferred to the air passing under and resulted more heat loss by convection and radiation. When Fr and Ul values which were characteristics of solar air heating system with conical concentrator were examined, Fr was found to be 0.2 and 0.9 in natural and forced convection flow conditions respectively. Since the space between absorber pipe and glass was not under vacuum, the values of Ul were usually very high especially at forced convection conditions. These values, however, could be decreased by using packing material and selective surface. Pumping powers of 0.7 W with packing and 1.5 W without packing for air circulation in the system with conical concentrator were required. The air heated by conical concentrator was used in apricot drying. With the drying operation conducted at a variety of air flow rates, it is seen that the system could be used effectively and efficiently in drying of apricots which play an important role inX the economy of Turkey and the region, by shortening 2 days the drying time of apricots compared with open drying under the sun. Single particle experiments in the laboratory conditions were also undertaken to search steady and continuous drying kinetics of apricot samples being dried in solar energy system and treated previously with SO2. It was observed that air flow rate was much more important than air temperature, drying occurred in decreasing drying rates period, the change in moisture content could be expressed by an exponential relation in the form of Mr = a.exp`kt and increasing with temperature and air flow rate, diffusion coefficients have taken values varied between 2.86xl0`7 - 4.99 xlO`7 m2/hr. Keywords: Solar energy, conical concentrator, air heating, drying, apricot drying. Ill ÖZET Doktora Tezi KURUTMADA KONİK YOGUNLAŞTIRICILI BİR GÜNEŞ ENERJİSİ SİSTEMİNİN KULLANILMASI inci TURK TOĞRUL Fırat Üniversitesi Fen Bilimleri Enstitüsü Kimya Mühendisliği Anabilim Dalı 2001, Sayfa:264 Güneş enerjisi, yeni ve yenilenebilir bir enerji kaynağı oluşu yanında bir sorun olan çevreyi kirletici atıklarının bulunmayışı, yerel olarak uzun ve karmaşık bir teknoloji gerektirmemesi gibi üstünlükleri sebebiyle son yıllarda yoğun çalışmaların yapıldığı bir konu olmuştur. Binaların ısıtılması, endüstriyel ürünlerin kurutulması ve elektrik üretimi güneş enerjisinin kullanıldığı alanlardır. Yüksek sıcaklık uygulamalarında güneş yoğunlaştırıcılarının kullanılması gerekir. Düz toplayıcılarla aynı açıklık alanına düşen güneş ışınımından, yoğunlaştırıcılı toplayıcılardan daha fazla miktarda faydalanabilir, fakat yoğunlaştırıcılı toplayıcılarla daha yüksek sıcaklıklara ulaşılabilir. Türkiye güneş enerjisi açısından zengin bir ülkedir ve bugün 90°C nin altındaki sıcaklık uygulamalarında düzlem yüzeyli güneş toplayıcıları yaygın bir şekilde kullanılmaktadır. Güneş enerjisi uygulama teknolojilerinin geliştirilmesi konusunda bugün çok sayıda araştırma yapılmaktadır. Ancak hava ısıtma söz konusu olduğunda yüksek sıcaklıklara çıkabilen sistemlerin olmaması eksiklik olarak görülmektedir.IV Bu çalışmada yüksek sıcaklıklara çıkabilmek amacıyla konik yoğunlaştırıcılı bir hava ısıtıcının tasannu yapıldı, kuruldu ve temel sistem parametreleri yönünden performansı incelendi. Şimdiye kadar kullanılan sistemlerden farklı olarak dizayn edilen ve yoğunlaştırıcı kısmı konik şekilli olan yansıtıcının odak noktasına silindirik bir absorber yerleştirildi. Koninin güneşi doğuşundan batışına sürekli izlemesi sağlanarak güneş ışınlarının günün her saatinde absorbere dik olarak yansıtılması sağlandı. Yeni tasarlanan bu konik yoğunlaştırıcılı hava ısıtma sisteminin doğal ve zorlanmış akış şartlarında performansı incelendi. Bu sırada üç ayrı eğim açısında yerleştirilen toplayıcının optimum eğimi belirlendi. 28.4°, 33.4° ve 38.4° açılarında yerleştirilen toplayıcıdan en yüksek sıcaklık ve verim değerleri 28.4° eğim açısında elde edildi. Sistem doğal akış şartlarında çalıştırıldığında çok yüksek sıcaklıklara (155°C) çıkabilmesine rağmen hava akış debisinin düşük olması nedeniyle verim %11 seviyesinde kalmıştır. 30 kg/saat-70 kg/saat aralığında 5 ayrı hava debisinde yürütülen zorlanmış akış deneylerinde ise en yüksek sıcaklıklar 30 kg/saat' te en yüksek verim (%50) değerleri ise 70 kg/saat hava debisinde elde edildi. Konik yoğunlaştırıcılı hava ısıtma sisteminin verimini artırmak için seçici yüzeyli absorber denendi. Bakır üzerine nikel kaplanmış yüzeye siyah krom ile renklendirme yapılarak elde edilen seçici yüzeyli absorber kullanımı ile sistemin doğal konveksiyon verimi %3.6, zorlanmış konveksiyon verimi %6 oranında artırıldı. Hava ısıtıcıların verimini artırmak için yaygın olarak kullanılan bir diğer yöntem de hava akış kanalına dolgu malzemesi yerleştirerek ısı transfer alanını artırmaktır. Bu amaçla absorber altındaki hava akış kanalına değişik sargı sayılarında katlanmış alüminyum sinek teli absorberle temas edecek şekilde yerleştirildi. 6,10 ve 14 kat sayılarında dolgu kullanılması ile genel olarak sistemin doğal konveksiyon veriminde düşüş, zorlanmış konveksiyon veriminde ise artış görüldü. Havanın doğal konveksiyonla sistemden geçtiği durumda akış kanalına yerleştirilen dolgu malzemesi havanın hareketine ilave bir direnç oluşturduğu için sargı sayısına bağlı olarak sistem verimi %31.5-%36.2 oranında düşmektedir. Zorlanmış akış şartlarında ise dolgu malzemesi kullanımıyla absorber altından akan havaya ısının aktarıldığı yüzey alanıarttığından sargı sayısına bağlı olarak verim %60-%80 değerlerine çıkmaktadır. Dolgulu ve dolgusuz durumda ısı transfer katsayıları hesaplandığında ise yaklaşık 10 kat artış olduğu görüldü. Hava akış kanalına dolgu malzemesi yerleştirildiği durumda seçici yüzeyli absorber kullanımında ise sistem verimi %85' e çıkarak, %68' e varan iyileşme elde edildi. Konik yoğunlaştırıcılı hava ısıtma sistemini verimini artırmak için ayrıca siyah boyalı absorber üzerine siyah boyalı alüminyum sinek teli sarılarak elde edilen absorber yüzey kullanıldı. Yapay olarak pürüzlendirilen absorber yüzeyinin doğal ve zorlanmış akış şartlarında sistemin verimini düşürdüğü görüldü. Pürüzlerden dolayı güneş ışımasını daha fazla absorblayarak verimi artırması beklenen yüzeyin absorbladığı ısıyı, absorber altından geçen havaya etkili bir şekilde iletemediği gibi konveksiyon ve radyasyonla çevreye olan ısı kaybım da artırdığı görüldü. Konik yoğunlaştırmalı hava ısıtma sistemine ait karakteristik özellikler olan Fr ve Ul değerleri incelendiğinde ise doğal akış şartlarında Fr' nin 0.2, zorlanmış akış şartlarında 0.9 mertebesinde olduğu görüldü. Isı kayıp katsayısı Ul ise absorber boru ile cam arasındaki yüzeyin vakumlanmamış olması nedeniyle, genel olarak, özellikle zorlanmış akış şartlarında yüksek değerlerdedir, ancak dolgu malzemesi ve seçici yüzey kullanımlarıyla bu değer düşürülebilmiştir. Konik yoğunlaştırıcılı sistemden havanın dolaştırılması için, dolgusuz durumda 0.7 W, dolgulu durumda ise 1.5 W pompalama gücüne ihtiyaç duyulmaktadır. Konik yoğunlaştırıcılı güneş enerjili sistemden elde edilen hava kayısı kurutmada kullanıldı. Farklı hava debilerinde yürütülen kurutma işlemi ile kurutma süresi güneşte kurutmaya kıyasla iki gün kısaltılarak Türkiye ve bölge ekonomisinde önemli yere sahip olan kayısının kurutulmasında etkili ve verimli bir şekilde kullanılabileceği görüldü. Güneş enerjili sistemde kurutulan önceden kükürt dioksit ile işleme sokulmuş kayısının yatışkın ve sürekli şartlarda kuruma kinetiğini araştırmak amacıyla laboratuarV] ortamında tek tane deneyleri yapıldı. Tek tane kayısı kurumasında hava sıcaklığından çok hava hızının önemli olduğu, kurumanın azalan kuruma hızı periyodunda gerçekleştiği, zamanla nem oranındaki değişimin en iyi MR = a.exp(-kt ) şeklinde üstel bir fonksiyonla ifâde edilebildiği ve difüzyon katsayısının sıcaklık ve hava hızı ile artarak 2.86xl0`7-4.99xl0`7 m2/saat arasında değişen değerler aldığı görüldü. Anahtar Kelimeler: Güneş enerjisi, konik yoğunlaştırıcı, hava ısıtma, kurutma, kayısı kurutma. 264

ÖZET Hidrolik sistemlerde esas olup istenen; yükü hareket ettirmek için kullanılan gücün, hidrolik pompayı tahrik eden elektrik motorundan çekilen güçle aynı olmasını sağlamaktadır.(verim hariç). Bu da pompanın tüm debisini sisteme göndermesi ve pompa çıkışında da yük direncine karşılık gelen basıncın görülmesi durumudur. Halbuki hidrolik sistemlerde; kullanıcıda hız ayarlarını yapmak için kullanılan debi ayar valileri istenmeyen güç kayıplarını dolayısıyla enerji kayıplarını ortaya çıkarmaktadır. Burada çeşitli durumlar için güç kayıplarının analizi yapılacak olup, bu güç kayıplarını azaltabilmek için değişken debili pompaların nasıl kullanılabileceği incelenecektir. Anahtar Kelimeler: Enerji kaybı, verimlilik, değişken debili pompalar. iv ABSTRACT In hydraulic systems the goal is making equivalent both power consumption of electrical motor transmission and power consumption of useful! force, (except efficiency therefore, the pump provide flow and we get pressure at the end of pump becoming from force resistance. However, all of flow control valves used as fluid velocity adjusting valves cause unexpected power losses. Hereby, we'll analyze power losses and we'll examine how we can use the variable displacement pumps in order to decrease power losses. Keywords: Energy lose, efficiency, variable deplacement pumps. 48

FARKLI YAPIM ÖZELLİKLERİNE SAHİP DOĞAL DOLAŞIMLI GÜNEŞLİ SU ISITMA SİSTEMLERİNİN DENEYSEL KARŞILAŞTIRILMASI (Yüksek Lisans Tezi) Ayhan BAYRAM GAZİ ÜNİVERSİTESİ FEN BİLİMLERİ ENSTÜTÜSÜ TEMMUZ 2001 ÖZET Bu çalışmada, 0,5 m2,lik güneş ışını toplama yüzeyine sahip 6 (altı) adet değişik yapı ve özelliklerdeki güneş kollektörlerinin sıcak su hazırlama performansları araştırılmıştır. Yapılan deneylerde sözü edilen 6 (altı) sistem aynı şartlarda denenerek verimleri birbirleri ile karşılaştırılmıştır. Karşılaştirma sonunda `Depo tip ışın toplayıcılı sistem` diğer sistemlerin performanslarının ortalamasından %17 daha fazla performans gösterdiği tarafımızdan tespit edilmiştir. Bilim Kodu : 600 11 01 Anahtar Kelimeler : Güneş enerjisi, güneşli su ısıtma, doğrudan dolaşımlı, dolaylı dolaşımlı. Sayfa Adedi : 50 Tez Yöneticisi : Doç. Dr. Hikmet DOĞAN EXPERIMENTAL COMPARISION OF SOLAR WATER HEATING SYSTEMS WITH NATURAL FLOWING, WHICH HAVE DIFFERENT CONSTRUCTION SPECIFICATION (M. Sc Thesis) Ayhan BAYRAM GAZİUNIVERSTY INSTITUTE OF SCIENCE AND TECHNOLOGY July 2001 ABSTRACT In this work, the performances of hot water preparation of six solar collectors, which have 0,5 m2 solar beam collection surface with different specifications and construction have been investigated. The 6 systems were tested in experiments and the efficiency of them were compared with each other. At the end of comparison it has been determined that `Tank type beam collection system` had 17% more performance than other systems performances. Science Code : 600 1101 Key Words : Solar energy, solar water heating, direct flowing, indirect flowing Page : 50 Supervisor : Assoc. Prof. Dr. Hikmet DO?AN 50

ÖZET Yfiksek Lisans Tezi TÜRK KÖMÜRLERİNİN MİKRODALGA ENERJİSİ ETKİSİYLE TETRALİNDEKİ HİDROJENASYONU ÜZERİNDE NEMİN ETKİSİ Osama KONNA Ankara Üniversitesi Fen Bilimleri Enstitüsü Kimya Mühendisliği Anabilİm Dalı Danışman: Prof. Dr. Taner TOĞRUL Jüri: Prof. Dr. Güniz GÜRÜZ Prot Dr. Taner TOĞRUL Doç. Dr. Zeki AKTAŞ Bu çalışmada, değişik Türk kömürlerinin mikrodalga enerji etkisiyle tetralindeki hidrojenasyonu üzerindeki nemin etkisi incelenmiştir. Hİdrojenasyonla elde edilen sıvı ürünler yağlar, asfaltenler ve preasfaltenler olarak kesimlere ayrılarak ürün dağdmılan belirlenmiştir. Deneyler iki grupta gerçekleştirilmiştir. İlk grup deneylerde değişik nem oranlarına sahip kömür örnekleri 1/4 kömür/çözücü oranında ve 6 dk sûreyle hidrojenasyona tabi tutobnnştnr. Hidorjenasyon, % 100 güçte çalışan mikrodalga fırında gerçekleştirilmiştir. İkinci grup deneyler ise 1/2 ve 1/4 kömür/çözücü oram ve % 42.86 nem içeriğinde Beypazarı linyitinin dönüşümü üzerinde sürenin etkisi incelenmiştir.Değişik nem oranlarına sahip kömür örneklerinin mikrodalga radyasyonu etkisiyle hidrojcnasyon deneylerinde, dönüşümün önce azaldığı ve kritik bir nem değerinden sonra arttığı görfilmüştür. Surenin etkisini belirlemek amacıyla gerçekleştirilen deneylerde İse sürema artışıyla dönüşümün azaldığı görülmüştür. 2000, 78 sayfa Anahtar Kelimeler: Kömür, hidrojenasyon, mikrodalga enerji, nem. .-_ ABSTRACT... ^ *,** Masters Thesis EFFECT OF MOISTURE IN HYDROGENATION OF TURKISH COALS m TETRAMN BY MICROWAVE RADIATION ENERGY Osama KONNA Ankara University Graduate School of Natural and Applied Science Department of Chemical Engineering Supervisor: Prof. Dr. Taner TO?RUL Jury: Prof. Dr. Güniz GÜRÜZ Prof. Dr. Taner TO?RUL Assoc Prof. Dr. Zeki AKTAŞ In this study, effect of moisture in hydrogcnation of different Turkish coals in tetralin was investigated by microwave energy. The liquid products obtained from the bydrogenation were fractionated into oils, asphalthenes and preasphaltenes. Experiments were carried out in two groups. In the first group of experiments, different Turkish coals which in different moisture ratios were hydrogenated. Hydrogenation was conducted in a microwave furnace of which the frequency was 2,45 GHz. In the second, Beypazarı lignite which in 42.86 moisture ratio was chosen todetermine the effect of hydrogenation time on the conversion at the ratios of 1/2 and 1/4 coal/solvent The hydrogenation conversions of coals with the effect of microwave radiation were decreased at first and increased after critical moisture value. In determine of the effect of the time conversion decreased with increas in time. 2000, 78 pages Key Words: Coal, hydrogenation, microwave energy, moisture. IV 78

Özet İnsan plasentasından 29.1 kat saflaştınlan alkali fosfatazın spesifik aktivitesi 6.40 IU/mg olarak bulunmuştur. Saflaştırma işlemleri, pH 8.6 tris tamponuyla homojenizasyon, butanol ekstraksiyonu, amonyum sülfatla çöktürme, ısı muamelesi ve Sephadex G-200 jel filtrasyonu basamaklarını içermektedir. Kısmen saflaştınlmış enzimin lineweaver-Burk grafiği çizilerek 37°C'de 0.1M Glisin- lmM Mg^ tamponunda (pH 10.5) p-NPP substratı için Km değeri 0.5 mM olarak saptandı. Enzimin p-NPP substratı için optimum pH'sı 10.6 olarak bulundu. Yapılan ısı ile inaktivasyon çalışmaları sonucunda, enzimin 65°C'de aktivitesinin hemen hemen %100'ünü koruduğu, 78°C'de ise aktivitesinin tamamını kaybettiği gözlemlenmiştir. Daha sonra enzim üzerine teobromin, ferrözsülfat, sodium tiyosiyanat ve etanol'un etkileri denenmiştir. Bunlardan etanol ve ferrözsülfaun enzimi inhibe ettiği ve etanol için inhibisyon tipinin karışık nonkompetetif olduğu, ferrözsülfat için ise inhibisyon tipinin unkompetitif olduğu saptanmıştır. Teobromin ve sodyumtiyosiyanatm enzim aktivitesi üzerine hiçbir etkisi gözlemlenmemiştir. Summary Alkaline phosphatase of human placenta was purified 29.1 fold with a final specific activity of 6.40 IU/mg by a procedure involving homogenization with tris buffer pH 8.6, extraction with butanol, ammonium sulphate precipitation, exposure to heat and Sephadex G-200 gel filtration. The apparent Km value of the purified enzyme for p-NPP in 0.1 M glycine- ImM magnesium buffer, pH 10.5 at 37°C was calculated (estimated) to be 0.50 mM from Lineweaver-Burk plot. The enzyme had a pH optimum 10.6 for p-NPP. Heat inactivation studies showed that the enzyme remained almost 100% stable at 65°C but it was completely inactivated at 78°C. Subsequently, the effects of theobromine, sodium thiocyanate, ferrous sulphate and ethanol on ALP were investigated. The inhibition type for ferrous sulphate and ethanol were uncompetitive and mixed noncompetitive respectively. However theobromine and sodium thiocyanate did not affect enzyme activity. 97

SUMMARY SOLAR CELL POWER PLANTS Extensive research and development activities are currently being conducted ali över the world in the area of utilizing renewable energy resources. The interest of the utilization of local renewable energy resources for devoloping countries has been enhanced by the dramatic increase of oil prices in the early seventies. Öne of the most promising renewable resources is the solar energy. The recent developments in the solid state industry accompanied by a parallel increase in energy prices and the environmental restrictions as well as the need for reliable sources of energy lead to the consideration and assessment of new sources of energy which can secure the needs of public with a minimum impact on the environment. An important candidate is the photovoltaic (PV) source of energy, where the solar radiation is directly converted into electricity that can either be residentially used as a local self-sufficient source such as telecommunication, vaccine refrigeration, lighting, battery charging and water pumping applications ör interconnected to available AÇ public grid. in this work about the photovoltaic systems that are connected to the grid, the voltage obtained from the array is converted to three phase sinusoidal voltage by a static inverter vvhich supplies the public grid and the system is simulated. A utility - interactive PV system (Figüre 1) consists of a variety of subsystems: a PV array subsystem, a power conditioning subsystem, a utility interconnection subsystem, and control subsystem. The PV array subsystem converts solar energy into direct current (DC) electrical povver and delivers it to the power conditioning subsystem (PCS) through the DC interface. The array subsystem also provides protection and necessary electrical isolation between the PCS and the array, and may include experimental instrumentation for monitoring the performance of the array. The utility interconnection subsystem, through the alternating current (AÇ) interface with the PCS, provides synchronization with the utility and, if necessary, acts to electrically isolate the PV system from the utility. The control subsystem, operating through the PCS, oversees the performance of the entire PV system. it also enables overall coordination of the system protection, communicates status information to the utility dispatch center, and, if desired, provides an information and tracking VIIfeedback loop with the PV array. in central PV stations, the PCS may also processes operational commands from the utility dispatch center. in operation, the PCS converts DC power from the array into AÇ povver, provides optimum amount of power to be extracted from the PV array for any given insolation and environmental conditions, matches frequency and phase of the voltage desired by the utility, and provides. protection not only for its internal components but also for the equipment external to the PCS..i, UTILITYCONTROL AND rı^MTi,TINFORMATION SIGNALS CONTKOL ^ SUBSYSTEM rJ^IS PVPOWER CON-UTILITY^- ARRAY-*- DITIONING -+.INTERCON.*~ SOLAR l SUBSYSTEMSUBSYSTEM SUBSYSTEM UTILITY ENERGY4 4 Figüre 1. Block Diagram of a Utility-Interactive Photovoltaic System To achieve a compatible integration of the PV system with the utility, it is essential that the design of the PCS accommodate the dynamic range of interactions between the PV system and the utility grid. These arise from changes in both grid conditions and the output of the PV array. The proper and safe interconnections of PV subsystems require not only the identifications of their mutual functional constraints, but also a knovvledge of how to select ör design the PV subsystems vvithin such constraints. These constraints, therefore, are important in the selection ör evaluation of a PCS that is suitable for central station PV systems. A solar celi (SC) generator possesses a line of maximum povver, and it is most desirable that the operation of the load line should be close to the maximum povver line of the generator. in such a case, good matching exists between the generator and the load for the best performance of the system and maximum utilization of the solar cells. The VIII-Toperating points of the photovoltaic system can generally be accomplished by either carefully selecting the I-V characteristics of the load to be connected to the SC generator, ör incorporating an electronic control device (a maximum-power- point-tracker (MPPT)), which provides the necessary impedance matching the SC generator and the inclusion of a MPPT in PV systems depends on several factors: load type and profile; climatic conditions; the fractional cost of the MPPT and its efficiency; and the gain in energy. An electrical circuit design can be simulated before it is actually built, and necessary changes may be done without touching any hardvvare. Any design that is thought to be complete can be checked easily. Building an electrical circuit is the most practical way to check it, but it is expensive and time consuming. it is useful to simulate the design carefully by using a computer program. Figüre 2 shows the PV system simulated by using PSpice which is a member of the Spice (Simulation Program with Integrated Circuit Emphasis) family of circuit simulators. The solar celi is a semiconductor device that converts the solar radiation directly to electrical energy. The celi is a nonlinear device and can be represented by the I-V terminal characteristics, Figüre 3, ör by an approximate electrical equivalent circuit as shown in Figüre 4. The solar celi is an electrical celi of low level voltage and power, therefore the cells are in series and in parallel combinations in order to form an array of the desired voltage and power levels. The I-V equation of a single celi is given by: I = İL - Is [exp[(q/nkT). (V + RsI) - l] ] where İL is the light generated current, Is is the saturation current, kT/q is the thermal voltage, n is the perfection factor, Rs is the series resistance of the celi. For each characteristic curve there is an optimum operating point with respect to the power. Proper load selection allows the maximum power to be transferred. in this work, to convert the DC voltage into three phase sinusoidal voltage, a three-phase bridge inverter is used. The power circuit of a three-phase bridge inverter using thyristors is shown in Figüre 5, where commutation and snubber circuits are omitted for simplicity. The inverter consists of three half bridge units where the upper and lower thyristors of each unit are switched on and off alternately for 180° intervals. The three half-bridges are phase-shifted by 120°. The inverter output voltage wave shapes are determined by the circuit configuration and switching pattern. These waves are rich in harmonics. IX-T* *T`U_ -mrrru. rv» <D-^ PU ARRAY INUERTER UT ILIT V QRID INPUT FILTER OUTPUT FILTER Figure 2. Block diagram of the PV system simulated by using PSpice Figure 3. Characteristics of a solar cellRs I î I * * l IU<2pİ İDippSRCLoad) iii»»l Figüre 4. Solar celi equivalent circuit The inverter is provided with a filter, to make the output voltage (nearly) sinusoidal. in this study, a band-pass filter is chosen, as it is a simple and economical solution for the system. The transformer coupling to the grid supplies the filtered output voltage of the inverter into the grid. The model of ali components of the system is constituted by using their equivalent circuits and the system is simulated completely step by step. 178

SUMMARY INVESTIGATION OF HEAVY METAL EMISSIONS OF COALS DURING COMBUSTION FROM HOT WATER BOILER AND STOVE Coal is likely to become an increasingly important fuel for electrical energy production during the next two decades. This trend appears inevitable due to the decreased emphasis on the construction of nuclear plants and relatively minor short-term impact usually projected for alternate energy sources (solar and geothermai). The emissions of environmental concern from coal fired plants may be divided into four categories: (1) SO2 and SO3 (2) NO and NO2 (3) organic compounds and (4) inorganic compounds. The organic and inorganic compounds include both gas phase emissions (such PAH emissions and mercury vapor) and particulate emissions (e.g. soot and fly ash). While the chemistry associated with the formation and ultimate fate of coal sulphur and nitrogen has been fairly well-defined, until recently the chemical nature and fates of the remaining trace elements during and following combustion have attracted considerably less interest. The control of particulate emissions has been of concern for many years, but with emphasis being placed primarily on the visible stack emissions from the combustion facilities. Recent research into the nature of the inorganic emissions from coal-fired power plants, however, has given reason for renewed concern. These results indicate that particulate emissions may be greatly enriched in certain trace elements, and that these trace elements may be in chemical for physical forms, which have an enhanced impact upon man. To understand the complex chemistry involved in the trace element enrichment process during coal combustion one must know something of the chemical/or physical nature of these elements in coal. The majority of trace elements in coal are associated with the inorganic mineral matter present in all coals. This mineral matter consists primarily of clays (aluminosilicates), quartz (SİO2), carbonates, sulphides, sulphates and oxides. The trace elements may also be associated with the coal macerals, having been present in the original vegetation from which the coal was formed. While many trace elements, have primarily either organic or inorganic associations some trace elements show an affinity for both fractions. During combustion the mineral matter undergoes both decomposition and transformation reactions which may result in the release of the more volatile elements. The ultimate fate of the trace elements will largely depend oncontent and initial concentration of the trace elements in the coal combustion temperature of the facilities particle size of the ashes, operation temperature of the control systems. In recent years, attention has been directed rather more to the elemental composition of the dust rather than to its nuisance value with some stress on the trace elements likely to be present-particularly the heavy metals. Whereas the coal before combustion has on elemental composition broadly similar to soils and crustal rocks-and hence similar to the natural dust content of the atmosphere the combustion process acts to concentrate a number of elements into the ash and dust by a concentration factor of five or six. Beyond this, a number of the more volatile elements re-condense after combustion preferentially on to the finer particles-because of their greater specific surface area enhancing the concentration of these elements by on even greater factor. Elements may be divided into two groups on the basis of their concentration dependence upon particle size: those, which show no enrichment in the smallest particles, and those, which are enriched. The primary interest is with the enriched elements, since they are most likely to have a significant environmental impact. Results of analyses of fly ash as a function of particle size at laboratory indicate that the elements Mn, Ba, V, Cr, Co, Ni, Cu, Ga, Nd, As, Sb, Sn, Br, Zn, Se, Pb, Hg and S are volatilized to a significant extent in the combustion process. The elements Mg, Ti, Na, K, Mo, Ce, Rb, Cs and Nb appear to have a smaller fraction volatilized during coal combustion, or have significant variations in behavior between plants. The remaining elements, Si, Al, Fe, Ca, Sr, La, Sm, Eu, Tb, Py, Yb, Y, Sc, Zr, Ta, Na, Th, Ag and In, are either not volatilized, or may show minor trends which might be related to the geochemistry of the mineral matter. The most important phenomenon of the trace element distribution is that of the vaporisation-condensation, which is present in all stages of combustion process. That is why the combustion temperature has the most relevant role to play in the distribution of trace elements in combustion products, the ideal situation is to have an exact knowledge of the chemical form of the elements and the operating temperature of the boiler and of the control systems. Thus, it should be possible to determine the fate of the trace elements fairly exactly. The analytical results provide firm evidence that a volatilization-condensation process account for the trace element enrichment observed in the fly ash emitted from coal-fired power plants. The enrichment process results from condensation of volatilized material preferentially upon the smaller fly ash particles. A relationship in which the concentration is proportional to D`2 usually applies for particles larger than 1-15 um in diameter. For smaller particles, in situations where other particle formation mechanisms become, important, or where the thickness of the condensed material becomes appreciable, a more detailed approach appears to more correctly describe the concentration dependence upon particle size. In some cases, the concentration of volatilized elements becomes independent of particle size for particles as large as several microns in diameter. Some mechanisms have been postulated to explain these observations. xiIf the combustion conditions are always maintained the same and the coals used come from the same coal basin, which mean similar properties and rank of coal, a prediction of the trace elements destination in the final products, through correlations and the mathematical models, will be possible The volatilized elements, which condense upon, fly ash before particulate collection devices are often emitted into the atmosphere in greater abundance by a factor of up to 10 or more than elements not volatilized. These elements include As, Sb, Pb, Cd, V, Mo, Zn, Ga, Cr and U. These elements would typically have a 10-10 greater probability of pulmonary deposition upon respiration. Elements which are totally volatilized during combustion and which do not condense on particulate matter before the pollution control devices will often be emitted to the atmosphere in approximately 10 or greater abundance than elements not volatilized during combustion. These elements include the hologens, Hg, significant partions of the Se, B and perhaps-other elements such as Pb and Sb. These elements have 10 -10, or even greater, probability of pulmonary deposition upon respiration respiration than elements not volatilized during combustion. Further, these elements may be enriched by two to three orders of magnitute in the low temperature coal ash compared to their crustal abundance, leading to enrichment factors of 10 or greater for pulmonary deposition relative to the crustal abundance. The situation for the elements which are primarily in the gas phase at stack temperatures is similar to organic compounds, which include numerous mutagenic polycyclic aromatic hydrocarbons, which also rapidly become associated with the fly ash after leaving the stack by either condensation or adsorption processes. There are still several major gaps in existing knowledge of the trace element chemistry during coal combustion processes. When these gaps are filled, it should be possible to predict (at least semiquantatively) the extent of trace element emissions for a certain coal in a given coal-fired power plant. As noted above, the major affecting the trace element emissions from coal-fired power plants is the volatility, of the element during the combustion process. This necessarily involves a more complete understanding of volatilization from complex mineral phases and the fate of `organically-associated` species during combustion. In addition to the volatility of trace elements, the particle size distribution plays a major role in determining the emission rates for elements, which condense before the particle collection devices. Shifting the size distribution to smaller sizes will increase the emission rates due to a drop in collection efficiency for nearly all devices for 0.1-1.0 jim diameter particles. The size distribution may be altered by the combustion conditions. Research is necessary to determine the size distribution of particles resulting from the bursting or fracturing process and the dependence on combustion conditions and coal composition. Since the major parameters are likely to be the heating rate and composition of the particle, this process may be amenable to quantative treatment Regardless, it is important to determine if increased combustion xutemperatures necessarily increase the abundance of submicron particles if so, this factor would have to be considered in evaluating the advantages of increased combustion temperatures (e.g. increased plant efficiency, lower emission rates for other pollutants, etc.). Research must also address questions concerning the rate particle growth during combustion. Other problems involve the nature of the diffusion and crystal growth of trace species in ply ash particles after formation. Increased efforts should also be applied to the development of techniques for actual sampling of the high temperature combustion region. Ideally, these techniques should analyze major, minor and trace species in the gas phase and the particle size distribution well in to the condensation nuclei range, as well as elemental concentrations in the particulate matter as a function of particle size. Knowledge of the size distributions and compositions of the particulate phase through a combustion facility will be vital 10 a complete understanding of the combustion process and fly ash formation. The impact of new combustion and pollution control technologies must be care fully evaluated. And, there is an obvious need for more extensive and careful measurements of trace element emissions and particle size distributions from the various types of coal- fired plants. For example, particulate sampling methods need to be developed which avoid the loss of components with high vapour pressures. To increase the usefulness of these measurements, the coal should be analyzed, and the affinities determined for important trace element. Attempts should also be mode to determine the particle size distribution before the pollution control devices, and in the plume after most species emitted in the gas phase have become associated with the particles. There is also a need to understand the chemical and physical processes which the rates and temperatures at which the volatile species become associated with fly ash. A drop in the operating temperatures of pollution control devices may significantly reduce the emissions of these species. The correlation of these data with plant design and combustion conditions con provide both valuable emprical data on other factors affecting trace element emission rates and the means of greatly limiting the atmospheric discharge of trace element. To emphasize the effect of domesting heating to the air pollution in Turkey, concentrations of heavy metals in gas phase and in particular phase emitted from some kinds of lignite which are combusted extensively using the boiler and the stove have been studied. Gas sampling was carried out by passing the flue gas, sampled by a pump, through a thimble to remove the solid particles and extracting the trace elements in impingers including 0.1 N nitric acid. The stack particulates were sampled isokinetically using Andersen Universal Stack Sampler for the boiler and the small system for the stove and collected in the thimble for both stove and boiler. xmAll samples were chemically analyzed using a number of techniques including atomic absorption spectrophotometry. Datas of the coal combustion have been compared with each other and limit values of `Air Quality Assurance Regulation`. xiv ÖZET Hava kirliliğinin ülkemizde, özellikle bazı büyük şehirlerde giderek arttığı ve tehlikeli sonuçlar meydana getirdiği görülmektedir. Bu noktada dikkatler gerek enerji üretimi ve gerekse endüstriyel ve evsel gereksinmeler için yaygın olarak kullanılan kömür üzerine çekilmelidir. Kömürlerin yaygın olarak kullanılması diğer kirleticilerle birlikte ağır metallerinden atmosferdeki taşınımını arttırmaktadır. Bu çalışmada 80 000 kcal/h kapasiteli, TSE belgeli, elle yüklemeli, ızgaralı, üstten yanmalı ve iki kapaklı sobada çeşitli kömür örnekleriyle yanma deneyleri gerçekleştirilmiştir. Kazan deneylerinde %37 nemli Yeniköy Ağaçlı, nemi %20 civarına getirilmiş Yeniköy Ağaçlı-Güney Afrika harman, nemi %20 civarlarında bulunan Yeniköy Ağaçlı-Sibirya harman kömür örnekleri, soba deneylerinde %37 nemli Yeniköy Ağaçlı, nemi %20 civarına getirilmiş Yeniköy Ağaçlı-Güney Afrika harman, nemi %21 civarlarına getirilmiş Yeniköy Ağaçlı, nemi %15 civarına getirilmiş Yeniköy Ağaçlı kömür örnekleri kullanılmıştır. Yanma deneylerinde gerçekleştirilen emisyon ölçümleri sonucunda her kömür için ağır metallerin toz ve gaz fazdaki atmosferik yayınımlarına yanma sistemlerinin ve kömür cinslerinin etkileri araştırılmış ayrıca elde edilen sonuçlar Türk ve Alman yönetmeliklerinde (Hava Kalitesinin Korunması Yönetmeliği ve TA-Luft) sınır değerlerle de mukayese edilmiştir. ıx 132

ÖZET Güneşli su ısıtma sistemlerinin bilgisayarlı simulasyonu, Ekonomik fizibilitesi ve optimizasyonu SUCU, Necdet Yüksek Lisans Tezi, Ekonometri Anabilim dalı Tez yöneticisi, Yrd. Doç. Dr. H. Ahmet AKDENİZ MART 1996, 85 Sayfa Günümüzde enerjinin temininde güneş enerjisi gibi yeni enerji kaynakların da kulanılması gerekmektedir. İklim şartlarının uygun olduğu Türkiyemizde arzu edilen seviyede değildir. Bu çalışmada, güneşli su ısıtma sistemlerinin verimliliği, kollektör yüzeyinin optimum büyüklüğü, geri ödeme periyodu ve yıllık güneş enerjisi kazancı sayısal değerleri elde edilebilmesi için Basic programlama dilinde programlar geliştirilmiştir. Bunlar f- grafik metodu ve G>-f grafik metodu alt programlandır. Elde edilen sonuçlar grafikleri ile değerlendirilerek, İzmir çevresi için ev tipi ve endüstriyel tipi kullanımlara, klasik yakıtlara göre kıyaslama imkanı getirilmiştir. Bilgisayarlı simulasyon için bilgisayar programı hazırlanarak, alternatif sistem araştırılması için sunulmuştur. Programın yardımı ile aylık ve yıllık faydalı enerji verimliliği ; kollektör sayısına göre, markanın değişimine göre, tek yada çift depo kullanımına göre, kollektör sıvısının farklı absorbe değerlerine göre, birim kollektör alanı için depo hacminin değişimine göre elde edilerek grafik ile gösterilmiştir. rv ABSTRACK Computerized simulation of the solar water heating systems, economic feasibility and optimization Nowadays it is essential to use some other new sources of energy such as solar energy to produce energy. Although the clime of Türkiye is better than the European countries the solar energy is used less in our country. In this study ; Basic programmes have been developed to get the numeric values of the productivity of heating system with solar energy, the optimum greatness of the surface of a collector the payback period, the profit of annual solar energy. They are subprogrames of the method of f- chart and <D-f chart methods. By comparing the graphics, the results shows the possibility of comparision between the classic energies and the accomoditition arround Izmir and industrial types of usage. Preparing the programmes for computerized simulation the alternative system research has been suggested. By means of this programme the useful efficient of energy monthly or annually, according to the number of collectors, differences of types, the usage of one or two tanks, the different absorbing values of collector liquid, and the difference of hugeness of a tank for a collector. It has been produced and shown by a grafic. 85