Hüseyin Kurt

An Investigation into the Effects of Box Geometries on the Thermal Performance of Solar Cookers

The effect of box geometry, such as cylindrical and rectangular, on the performance of solar cookers has not been investigated. In this study, two different model box type solar cookers, which are in rectangular and cylindrical geometries, were constructed using the same material and were tested to investigate the effects of box geometries on the cooker performance. The experimental studies were conducted under the same operating conditions. The obtained results from the experiments were used to calculate the thermal efficiency and specific and characteristic boiling times. These parameters of the cookers were determined for 0.5, 1, and 1.5 kg of fresh water. It is observed that the cylindrical model has higher temperatures than the rectangular model under the same operating conditions. The thermal efficiency increased from 12.7 to 36.98% for cylindrical and 9.85 to 28.25% for rectangular model, when the quantity of water was increased from 0.5 to 1.5 kg; similarly, the characteristic boiling time was decreased from 39.56 to 14.35 for the cylindrical and 43.74 to 15.77 (min m−2 kg−1) for the rectangular model, respectively. The cylindrical model provided high thermal performance, which is indicated by high thermal efficiency and low characteristic boiling time, in comparison with the rectangular model.

Estimating Seebeck Coefficient of a p -Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception

Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit (ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.

Kümen Üretim Tesisi Isı Değiştiricisi Devresinin Statik Simülasyonu

A Heat Exchanger is device which realises thermal internal energy between two or more liquid, solid or liquid or solid particles and fluids without heat and occupation input outside. According to usage purposes heat exchangers may be in various constructions, capacity, size and types. Heat exchangers used for intentional heat recovery have an important situation of investment cost in industrial organizations. Therefore it should be considered quite while heat exchanger selected or heat exchanger circuits designed and it is required to designing correct heat exchanger or an effective heat exchanger network. In this study, it is made of static simulation that heat exchanger network which is found in a cumene production plant. By coordinates of hot and cold flows which enters to circuit and goes output from circuit are defined with matrix equations that temperature distributions in network and temperatures output network are obtained in high accuracy without to recourse iteration, specific software and hardware. In consequence of simulation the temperatures belonging to hot and cold flow passed from each cell in the heat exchanger network are obtained to coincide with the operating conditions in intrinsic accuracy. In addition thereby the temperature distribution within the circuit of the heat exchanger are obtained, following static state of circuit is provided.

SIVILAR İÇİN ISI İLETİM KATSAYISI ÖLÇÜM CİHAZININ TASARIMI, İMALİ VE TEST EDİLMESİ

Bu calismada, sivilarin isi iletim katsayisini olcebilmek amaciyla silindirik metoda gore olcum yapan laboratuartipi cihaz tasarimi yapilmis ve deneysel olarak test edilmistir. Cihazin dogrulugu, isi iletim katsayisi bilinen safsu ile 10-40 °C sicaklik araliginda yapilan deneylerle test edilmistir. Saf su ile yapilan deneylerden elde edilensonuclara gore, olculen sicaklik degerlerinden hesaplanan isi iletim katsayisi ile fiziksel ozellik tablosundanalinan degerler arasindaki maksimum bagil hata % 13.4, ortalama bagil hata ise % 7.6 olmustur. Saf su ileyapilan test deneyleri sartlarinda, farkli oranlarda saf su-antifriz karisimi, antifriz ve tuzlu su cozeltisinin isiiletim katsayilarini belirleyebilmek amaciyla deneyler yapilmis, saf suda oldugu gibi deney sonuclarina gore isiiletim katsayilari hesaplanmistir. Hesaplanan degerlerin regresyon analizi yapilarak, isi iletim katsayilarisicakligin ve saf su icerisindeki madde miktarinin fonksiyonu olarak ifade edilmistir.