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Utilizing electricity from renewable resources is very attractive to decrease the dependence on fossil fuels. As a result, hybrid power systems are gaining more attention. This paper focuses on the optimal design and dynamic simulation of renewable-based, hybrid standalone power systems. The designed system is able to meet the energy need of a building with 5 kW peak electricity demand. Both the technical and economic feasibility of the system was investigated under various climatic conditions of Turkey. Diesel fuel consumption, energy cost and annual CO2 emissions were estimated and compared with the diesel generator-only system. A parametric analysis was also conducted to understand the impact of the capacity of the PV array, wind turbine and the battery on the CO2 emissions and the levelized cost of energy. The system in each location was optimized based on the minimum energy cost and CO2 emissions. (C) 2020 Elsevier Ltd. All rights reserved.

This work presents a thermodynamic evaluation of an operating geothermal ORC power plant. The model is realized by using measured data of AFJET geothermal power plant which has 3MWe net power output capacity. Thermodynamic assessment of the system is conducted to see the energy and exergy efficiencies of each component, and the whole plant. Additionally, a parametric study is conducted to understand the effects of various operating conditions on the system performance. Different from previous studies, daily and annual net power output profile of the plant was investigated with considering ambient temperature fluctuations. Results revealed that net power output can drop as significant as 36% from winter to summer months. Also, between nighttime to daytime, the net power expectation may decrease by 5%. The exergy destruction rate of re-injection process constitutes the most significant part (38.1%) of the total exergy destruction of the plant. The conversion and exergy efficiencies of the system are calculated as 11.24% and 39.03%, respectively. Also, to enhance the performance of the plant, an internal heat recovery system is recommended. The analyses show that the implementation of an internal heat recovery system improves the energy and exergy efficiencies of the plant by 15%.

In this study, a solar-powered absorption cooling system was modelled using the TRNSYS software. The performance of the system was investigated using dynamic modelling under the weather conditions of Mugla, Trabzon, Izmir, Konya, Canakkale and Istanbul. The external catalog data file of the absorption chiller model was created to get more realistic results. A parametric study was carried out to evaluate the selected parameters’ influence on system efficiency. Various parameters such as solar collector type, area, storage tank volume, collector slope, boiler setpoint temperature, room thermostat set point temperature were investigated to see their impact on the performance of the solar-absorption system, in every city. Instead of using a constant boiler setpoint temperature, a novel control strategy is proposed. Besides, the payback period and the levelized cost of cooling of the optimized systems were studied. Results showed that, in terms of financial analysis, Izmir is the most suitable city for solar-based absorption cooling system applications with a payback period of 10.7 years. Trabzon is found to be the least suitable city due to the longest payback period, and the highest levelized cost of cooling among all locations.

Energy storage systems are being more important to compensate irregularities of renewable energy sources and yields more profitable to invest. Compressed air energy storage (CAES) systems provide sufficient of system usability, then large scale plants are found around the world. The compression process is the most critical part of these systems and different designs must be developed to improve efficiency such as liquid piston. In this study, a liquid piston is analyzed with CFD tools to look into the effect of piston speed, compression ratio and cylinder geometry on compression efficiency and required work. It is found that, increasing piston speeds do not affect the piston work but efficiency decreases. Piston work remains constant at higher than 0.05 m/s piston speeds but the efficiency decreases from 90.9 % to 74.6 %. Using variable piston speeds has not a significant improvement on the system performance. It is seen that, the effect of compression ratio is increasing with high piston speeds. The required power, when the compression ratio is 80, is 2.39 times greater than the power when the compression ratio is 5 at 0.01 m/s piston speed and 2.87 times greater at 0.15 m/s. Cylinder geometry is also very important because, efficiency, power and work alter by L/D, D and cylinder volume respectively.

The effective thermal conductivity (ETC) of multilayer thermal insulation materials was experimentally investigated as a function of temperature (0-25 A degrees C). The materials consisted of binary/ternary glass wools or ternary expanded polystyrene foams reinforced with aluminium foil. The experimental measurements were performed using a guarded hot plate with temperature differences of 5, 10 and 15 A degrees C. The results indicated that significant correlations exist between ETC and the characteristics of the materials with decreasing temperature. The ETC decreases with reinforcement with aluminium foil at the same temperature or with temperature differences of 5 and 15 A degrees C. In addition, it was clearly observed that the ETC decreases sharply with decreased temperature. Consequently, reflective materials may reduce the ETC at low temperatures.

The air quality and thermal comfort strongly influenced by the heat and mass transfer take place together in an automobile cabin. In this study, it is aimed to investigate and assess the effects of air intake settings (recirculation and fresh air) on the thermal comfort, air quality satisfaction and energy usage during the cooling period of an automobile cabin. For this purpose, measurements (temperature, air velocity, CO2) were performed at various locations inside the cabin. Furthermore, whole body and local responses of the human subjects were noted while skin temperatures were measured. A mathematical model was arranged in order to estimate CO2 concentration and energy usage inside the vehicle cabin and verified with experimental data. It is shown that CO2 level inside of the cabin can be greater than the threshold value recommended for the driving safety if two and more occupants exist in the car. It is also shown that an advanced climate control system may satisfy the requirements for the air quality and thermal comfort as well as to reduce the energy usage for the cooling of a vehicle cabin.

Determining the thermal conditions in an automobile and their effects on the driver is an important issue from both thermal comfort and driving safety points of view. Especially in hot summer season, the interior thermal conditions in automobile change rapidly when the air conditioning unit runs. In this study, standard air conditioning system is switched in an automobile parked in the sun and then the interior thermal conditions of the automobile are determined in detail during the 1-h cooling period. During the period, relative humidity, air velocity, air and surface temperature measurements are taken at numerous locations in the automobile. Moreover, in order to evaluate the effects of transient interior thermal conditions on the occupant, the skin temperatures of human body are measured at nine points. In addition to this, the thermal sensation of the human subject is also questioned during the cooling period. Subjective thermal comfort data is recorded using a questionnaire. The series of tests are conducted on two different automobiles, and the experimental results for both automobiles are presented and scrutinized. FIAT TOFAS Automobile Company

In this study, a three-dimensional transient numerical analysis was performed inside the automobile cabin during heating period. A three-dimensional vehicle cabin including glazing surfaces was modeled by using the real dimensions of a car. A virtual manikin with real dimensions and physiological shape was added to the model of the vehicle cabin. It was assumed that the manikin surfaces were subjected to either constant heat flux or constant temperature. Three-dimensional fluid flow, temperature distribution, and heat transfer characteristics inside the cabin were calculated. Experimental measurements were also conducted. Comparisons of the results were presented and discussed. The results of numerical calculations were in good agreement with the experimental and theoretical data in the literature. FIAT-TOFAS

In this study a combined computational model of a room with virtual thermal manikin with real dimensions and physiological shape was used to determine heat and mass transfer between human body and environment. Three dimensional fluid flow, temperature and moisture distribution, heat transfer (sensible and latent) between human body and ambient, radiation and convection heat transfer rates on human body surfaces, local and average convection coefficients and skin temperatures were calculated. The radiative heat transfer coefficient predicted for the whole-body was 4.6 W m(-2) K-1, closely matching the generally accepted whole-body value of 4.7 W m(-2) K-.(-1) Similarly, the whole-body natural convection coefficient for the manikin fell within the mid-range of previously published values at 3.8 W m(-2) K-1. Results of calculations were in agreement with available experimental and theoretical data in literature. (C) 2008 Elsevier Ltd. All rights reserved.

It is obvious that heat exchanger performance is highly related with fin material thermal conductivity. In this paper 3-D numerical simulations were performed for conjugate heat transfer and fluid flow characteristics of fin and tube heat exchanger. The effects of the fin materials interacting with five factors: Reynolds (Re) number, fin pitch (FP), fin thickness (FT), tube diameter (TD) and fin length (FL) were examined. However, high thermal conductivity materials may not be suitable under some operating conditions such as food processing. It is found that thermal conductivity of the material slightly increases the effect of the Re number on Nusselt (Nu) number and the thermal conductivity is becoming very important parameter while investigating the effect of tube diameter on Nu number. Similarly the effect of fin length and fin thickness is also affected by fin material. A new correlation is proposed to predict Nu number includes the effect of all these parameters. Isı değiştirici performansının, kanatçık malzemesinin ısıl iletkenliği ile yüksek bir alakası olduğu açıktır. Bu çalışmada, kanatlı borulu ısı değiştiricinin bütünleşik ısı transferi ve akış karakteristiklerini belirlemek için üç boyutlu modelleme ile sayısal hesaplamalar yapılmıştır. Kanatçık malzemesinin etkisi şu beş faktör ile birlikte incelenmiştir: Reynolds sayısı (Re), kanatçıklar arası mesafe (FP), kanatçık kalınlığı (FT), boru çapı (TD) ve kanatçık uzunluğu (FL). Bununla birlikte yüksek ısı iletim katsayılarına sahip malzemelerin gıda işleme gibi bazı proseslerde kullanılması uygun olmayabilmektedir. Malzemenin ısı iletim katsayısı, Re sayısının Nu sayısı üzerindeki etkisinde ufak bir artışa sebep olmakla birlikte boru çapının Nu sayısı üzerindeki etkisi incelendiğinde önemli bir parametre olduğu bulunmuştur. Benzer olarak kanatçık uzunluğunun ve kanatçık kalınlığının etkileri de kanatçık malzemesinden etkilenmektedir. Nu sayısının bulunması için bütün bu parametrelerin etkilerini içeren yeni bir korelasyon önerilmiştir. Scientific and Technology

Bu çalışma, 10-11 Haziran, 2016 tarihlerinde Smolyan[Bulgaristan]’da düzenlenen 15. International Scientific Conference on Renewable Energy and Innovative Technologies‘da bildiri olarak sunulmuştur. In order to design adsorption employed cooling or refrigeration system, it is inevitably required the knowledge of the adsorption isotherms and the isosteric adsorption heat for the assorted adsorbent/adsorbate pair. The physical adsorption phenomena occurs mainly within the pores and on the surface of the adsorbent. Since, the characteristics of each adsorbent-adsorbate pair is different than others. The knowledge of adsorption characteristics with the variation of temperature and pressure is necessary for the evaluation. However, these data are usually unavailable from the manufacturers of adsorbents. The objective of this study is to evaluate adsorption characteristics of R134A (HFC-134A) and R404A (HFC-404A) on different adsorbents experimentally by a constant volume variable pressure method at different adsorption temperatures ranging from 20 to 50 C and for pressures up to 5 bar. The forms of the isotherms obtained from the experimental measurements are similar in all cases and comparable to those reported in the literature for commercially available different adsorbents. Adsorption parameters are evaluated from the isotherms using the Dubinin-Astakhov (DA) equation. The concentration dependence of the isosteric enthalpies of adsorption is extracted from the obtained data. Further, the enthalpy of adsorption data are extracted, and correlations are provided for the different specimens investigated. These data are essential for the design of a thermally driven adsorption chiller employed the assorted pair.

Bu çalışma, 10-11 Haziran 2016 tarihlerinde Smolyan[Bulgaristan]’düzenlenen 15. International Scientific Conference on Renewable Energy and Innovative Technologies Kongresi‘nde bildiri olarak sunulmuştur. Renewable energy systems (RES) require more efficient, reliable and cost effective energy storage systems to benefit more from these kind of environmentally friendly energy sources and reduce CO2 emissions. Compressed air energy storage (CAES) is one of the mechanical energy storage technologies that uses pressurized air to store and generate power when needed. Small scale CAES systems has been developed for RES application due to its advantages like easy installation, low maintaining costs, modular structure and running up time. In this study, a new small scale CAES system, which is running with liquid pistons to obtain isothermal compression and expansion, and a pressure regulator to compensate pressures between liquid pistons and air, is suggested. A detailed description of the novel CAES system design is given and effect of the components' specifications of the system are explained. Experimental results showed that, designed CAES system is a promising technology for RES, standalone and mobile applications. Specific components compatible with operating conditions of the system need to be designed in order to improve effectiveness and reliability.

In this study, apart from the other studies related to thermal comfort, it is combined that the fundamental equations given in the steady-state energy balance and the empirical relations expressing effects of the thermoregulatory control mechanisms of the body. In the first section of this simulation, body core temperature is calculated by using the equations expressing thermoregulatory control mechanism, the required skin temperature and sweat rate values. Variation of the calculated body core temperature is investigated with the activity level based on required skin temperature and sweat rate values. In the second section of the simulation, heat losses from the body (convection, radiation, evaporation, and respiration) and ratio of the each heat loss mechanism to total heat loss are calculated and discussed in detail.

In this study, a theoretical approach is proposed for the prediction of time and temperature during the heat charge and discharge in the latent heat storage of phase changed materials (PCM). By the use of the average values of the mean specific heat capacities for the phase-changed materials, analytical solutions are obtained and compared with the available experimental data in the literature. It is shown that decreasing the entry temperature of the working fluid from −4 to −15°C has a very dominant and strong effect on the PCM solidification time. The effect of the working fluid flow rate and the material of PCM capsules on the time for complete solidification and total charging is also investigated. The agreement between the present theoretical model results and the experimental data related to the cooling using small spheres and the heat storage using rectangle containers is very good. The largest difference between the present results and the experimental data becomes about 10% when the fluid temperature approaches the phase change temperature at high temperatures. Copyright © 2006 John Wiley & Sons, Ltd.

In industrialized countries about 90% of the time is spent indoors. In indoor, thermal comfort can be basically predicted by the environmental parameters such as temperature, humidity, air velocity and by the personal parameters as activity and clothing resistance. In this study, a mathematical model of thermal interaction between human body and environment was established and the effect of clothing and air velocity was examined under transient conditions. By the developed model, human body has been separated to 16 segments and possible local discomforts are taken into consideration. Using the model, changes in the sensible and latent heat losses, skin temperature and wettedness, thermal comfort indices were calculated. In a hot environment latent heat loss increases by means of sweating. Because of over wetted skin, comfort sense goes worse. Especially, at feet and pelvis skin wettedness reaches maximum level. Sensible and latent heat losses rise and the skin temperature and wettedness decrease with increasing air velocity.

Most vehicles have a heating, ventilation and air conditioning (HVAC) device to control the thermal environments of interior of the vehicle. But, under hot summer season or cold winter conditions, it is difficult to achieve and maintain thermal comfort in an automobile from the start up to the steady-state conditions. During these transition periods, an understanding of human thermoregulatory processes facilitates the design and development of improved heating and cooling systems. This study presents a model of thermal interactions between a human body and the interior environment of an automobile. The model is based on the heat balance equation for human body, combined with empirical equations defining the sweat rate and mean skin temperature. Simulation has been performed by the use of transient conditions. The effects of both heating and cooling processes on the thermal comfort inside the automobile are investigated. Results are compared with the present measurements and available experimental data in the literature. It is shown that the agreement between the experimental data and the model is very good.

The human thermal environment can be represented by the air temperature, radiant temperature, air velocity, humidity, clothing and activity. This has implications for health, comfort and performance. An understanding of human thermoregulatory processes facilitates the design and development of improved heating and cooling systems. This study presents a computational model of thermal interactions between a human and the interior environment. The model is based on the heat balance equation for human body with different types of clothing ensembles, combined with empirical equations defining the sweat rate and mean skin temperature. Simulation has been performed by the use of steady state conditions, and two different posture positions, namely sitting and standing, are considered in this study. Results are in good agreement with available experimental data. The parametric studies show that the methodology described can provide an effective means for simulating thermal comfort level.

Ambient conditions have significant effect on combined cycle power plants (CCPPs). Parameters-like efficiencies, fuel consumption, power production and even operation cost differ according to the ambient conditions that depend on the climate that cannot be changed. Therefore, deciding the location of the plant wisely would bring more efficient and profitable. In this paper, exergy analysis based on the second law of thermodynamics, considering environmental temperature variations, are performed for a cogeneration power plant. Mathematical model of analyse is introduced. Magnitudes of the variation of irreversibility, reversible power, power production and specific fuel consumption (SFC) are evaluated for the combined cycle. The results indicated that, decrease of environmental temperature augments the energy performance of the combined cycle form about 53% to 56% and improves the exergetic performance from about 51% to 56%. However, the augmentation via temperature decrease is not continuous. It is shown that the environmental temperature decrease causes a reduction about 5% in the SFC.

Bu çalışma, 07-08 Mayıs 2010 tarihleri arasında Bursa[Türkiye]’da düzenlenen 5. Automotive Technology Conference (OTEKON)’da bildiri olarak sunulmuştur. A three-dimensional (3-D) transient numerical analysis was performed inside an automobile cabin during cooling period. A three-dimensional vehicle cabin including glazing surfaces was modelled by using the real dimensions of a car. A virtual manikin with real dimensions and physiological shape was added to the model of the vehicle cabin, and it was assumed that the manikin surfaces were subjected to constant temperature. The virtual manikin was divided into 17 parts in standing posture to evaluate the local heat transfer characteristics of the human body during transient cooling period. We considered three different cases that the cooling capacity of the automobile cabin was same for all cases. Three-dimensional fluid flow, temperature distribution and heat transfer characteristics inside the automobile cabin were calculated with different type of inlet vents. Comparisons of the numerical results were presented and discussed.

The aim of this study is to investigate the transient effects of heater on temperature and humidity in an automobile cabin under transient heating period. Interior volume of an automobile is relatively small to other indoor environments, so that temperature and humidity values can rapidly change under highly transient conditions. Studies that are investigating the effects of heater on automobile cabin environment in real car conditions are restricted. Experiments were carried out in a parked car inside a laboratory at nights to prevent the possible wind and solar irradiation effects. In the experiments only plane vents were operated with three different air velocity levels. Temperature and relative humidity differences between air velocity levels were obtained, relations between time, temperature and relative humidity were calculated. From this study it is understood that temperature and relative humidity values inside a car vary directly from air velocity values. The obtained results can be used to improve other thermal comfort studies inside automobiles and also CFD analyses can be validated under transient conditions. Bu çalışmanın amacı ısıtıcının bir otomobil kabini içerisindeki sıcaklık ve bağıl neme olan anlık etkilerinin incelenmesidir. Otomobil kabini diğer iç ortamlara göre daha küçük olduğundan sıcaklık ve bağıl nem değerleri geçici rejim koşullarında çok hızlı bir biçimde değişmektedir. Isıtıcının otomobil kabini içerisindeki etkilerini gerçek kabin ortam koşullarında inceleyen çalışmalar oldukça sınırlıdır. Deneyler olası rüzgar ve güneş ışınımı etkilerini önlemek için laboratuarda park edilmiş bir otomobil içerisinde gerçekleştirilmiştir. Deneylerde üç ayrı hava hız düzeyi olan konsol menfezleri çalıştırılmıştır. Sıcaklık ve bağıl nem değerlerini hava hız düzeylerine göre farklılıkları ve zamana göre sıcaklık, bağıl nem değerleri arasındaki bağıntılar elde edilmiştir. Bu çalışmadan anlaşıldığı üzere araba kabini içerisindeki sıcaklık ve bağıl nem değerleri hava hızı değerlerinden doğrudan etkilenmektedir. Bu çalışmadan elde edilen sonuçların, otomobillerdeki ısıl konfor çalışmalarının geliştirilmesinde ve geçici rejim koşullarında gerçekleştirilen sayısal hesaplamalı akışkanlar dinamiği analizlerinin doğrulanmasında kullanılabilir.

In this study, 3-D numerical analysis of temperature distribution in the automobile cabin were performed by using computational fluid dynamics method. For this purpose, a 3-D automobile cabin including window and outer surfaces was modeled by using the real dimensions of a car. To evaluate the results of numerical analysis according to thermal comfort, a virtual manikin divided into 17 parts with real dimensions and physiological shape was added to the model of the automobile cabin. Temperature distributions of the automobile cabin were obtained from the results of the 3-D steady and transient numerical analyses for standard heating and cooling period. Validations of the results were achieved by comparing to the results of the experimental studies performed simultaneously with the numerical analyses.

A three-dimensional steady-state numerical analysis was performed in a room heated by two-panel radiators A virtual sating manikin with real dimensions and physiological shape was added to the model of the room and it was assumed that the manikin surfaces were subjected to constant temperature Two different heat transfer coefficients for the outer wall and for the window were considered Heat interactions between the human body surfaces and the room environment the air flow the temperature the humidity and the local heat transfer characteristics of the manikin and the room surfaces were computed numerically under different environmental conditions Comparisons of the results are presented and discussed The results show that energy consumption can be significantly reduced while increasing the thermal comfort by using better-insulated outer wall materials and windows. Dutch Prevention Funds Dutch ZON (Zorg Onderzoek Nederland) FIS (PI13/ 00061, PI13/01162) Health Research Fund LK Research Funds NKR Netherlands Cancer Registry National Cancer Institute (P30-CA008748) Prostate Cancer Foundation German Cancer Research Center Centre International de Recherche sur le Cancer National Research Council Sidney Kimmel Center for Prostate and Urologic Cancers Medical Research Council (MR/M012190/1) National Institute for Health Research Cancer Research UK (C8221/A19170) World Cancer Research Fund University of Oxford (R01 CA175491, R01-CA160816) European Commission Bundesministerium für Bildung und Forschung Cancerfonden (CAN 2017/559) Ministerie van Volksgezondheid, Welzijn en Sport Vetenskapsrådet (2016-02974) Instituto de Salud Carlos III (RTICC RD12/ 0036/0018) Associazione Italiana per la Ricerca sul Cancro Deutsche Krebshilfe European Regional Development Fund (C570/A16491) Clarendon Fund Hellenic Health Foundation

Infrared thermography is more convenient and faster than other temperature measurement devices such as thermocouples to measure more points or surfaces at the same time. In order to capture infrared thermograph of these surfaces, an infrared thermal camera which has a spectral range between 7.5 and 13 mu m was used. Using this technique will lead us to determine the instant and transient temperature distributions of all surfaces inside an automobile and investigate the thermal discomfort that was caused by those surfaces. FIAT - TOFAS

Isıl konforu etkileyen çevresel parametreler; iç ortam sıcaklığı, bağıl nemi, ortalama ışınım sıcaklığı ve kişi üzerindeki hava hızlarıdır. Bu çalışmada otomobillerin ısıtma sürecinde farklı hava yönlendiricileri seçimlerinde (konsol üzerindeki 4 hareketli menfezin açık tutulması, ön cam altındaki ve ayak hizasındaki sabit menfezlerin birlikte açık tutulması) sürekli değişen ve kabin içinde düzensiz bir dağılım gösteren ısıl konfor parametrelerinin değişimi deneysel olarak test edilmiş, hazırlanan simülasyon modeli kullanılarak sürücünün çevresi ile ısıl etkileşimi, fizyolojik tepkileri (deri yüzey sıcaklıklarının değişimi) ve ısıl konfor algıları hesaplanmıştır. Deneysel çalışmalarda sürücü üzerinden 11 noktadan ortam hava sıcaklığı, 17 noktadan hava hızı, sürücü koltuğu üzerinde tabandan 0.6 m yükseklikteki noktadan ortalama ışınım sıcaklığı ve sürücü nefes hizasından da bağıl nem ölçümleri alınmıştır. Teorik çalışmada anlık enerji dengesi modeli kullanılarak insan vücudunun 16 bölmeli modeli Matlab-Simulink ortamında hazırlanmıştır. Hazırlanan model literatürden alınan deneysel ölçümlerle karşılaştırılmış ve uyumlu sonuçlar elde edilmiştir. Otomobillerin ısıtma sürecinde yalnız konsol menfezlerinin açık tutulması ile sürücünün ayakları ve baldırları etrafındaki ortam havası yeterince ısınmamıştır. Vücudun menfez çıkış havası ile doğrudan temas eden bölmeleri üzerinde yüksek hava hareketleri oluşmaktadır. Deney başlangıcında düşük ortam sıcaklıklarında yüksek hava hızlarının sürücü üzerinde etkili olması ile özellikle konsol menfez seçiminde sol elden ve sağ koldan taşınımla ısı kayıpları artmış ve bu vücut bölmelerinin deri yüzey sıcaklıkları önemli oranda düşmüştür. Environmental parameters affecting the thermal comfort are; air temperature, relative humidity, mean radiant temperature and air velocities on human body segments. At this study, the effects of nonuniform and highly transient thermal comfort parameters were tested experimentally for two ventilation modes (panel vents, windshield and foot vents). With prepared simulation model thermal behavior, physiological reactions (skin temperatures) and thermal sensations of the driver were predicted. In the experiments air temperatures and velocities around the human body segments were measured at I I and 17 different points respectively. Relative humidity measurements were performed from the head region of the driver. In the theoretical studies, dynamic and close loop Matlab-Simulink model of the human body vas developed. In the simulation, the human body separated to 16 body segments to predict local dissatisfactions. The model was justified with the obtained experimental data from the literature. Studies revealed that heating the automobile compartment with panel vents mode air temperature at foot level could not reached desired values. For panel vents mode high air velocities affect driver body segments especially arms and hands owing to exposed vent air directly. This causes considerable temperature decline and low thermal sensations at skin surfaces.

The defogging process on a windshield is one of the important concerns in the automotive industry for driver safety and certification. Therefore, the simulation of the windshield defogging process provides a very effective and useful tool for the designers to obtain a more efficient and rapid defogging process. In this paper, an experimental and numerical study is presented for the windshield defogging process of an automobile. A computational fluid dynamics (CFDs) tool was used to perform the relevant three dimensional (3-D) transient simulations. Both droplet and wall film models are employed for comparison of the demisted area on a windshield in the numerical calculations. The 3-D fluid flow, temperature distribution and heat transfer characteristics of the interior surfaces of the automobile cabin are also considered. It is shown that the results of the simulations are in a good agreement with the experimental data presented in this study.

In this study, a detailed thermodynamic analysis of the water/lithium bromide absorption refrigeration cycle is performed. The influences of operating temperature and effectiveness of heat exchanger on the thermal loads of components, coefficients of performance (COPc, COP) and efficiency ratio (eta) are investigated. It is concluded that the COPc and COP values increase with increasing generator and evaporator temperatures but decrease with increasing condenser and absorber temperatures. The eta value varies with these temperatures. Also, the effects of solution and refrigerant heat exchangers on the performance, efficiency ratio of the system and fluid temperatures are compared. As a result, it is found that the solution heat exchanger (SHE) has more effect on the investigated parameters than the refrigerant heat exchanger (RHE). While the SHE increases the COP value up to a maximum 44%, the RHE has an effect of only 2.8%.

Cost analysis has a significant importance to obtain the optimum marketing price of the product of thermal systems to maximize the benefit and/or minimize the cost. Thus, this paper focuses on the investigation of the magnitude of the change in costs with respect to load and environmental temperature variations. To achieve the objective, a useful and simple second law based thermo-economic model with instant access to production costs is introduced and generalized. The presented exergy costing method indicates that the cost of reversible power is the theoretically minimum cost, where the reversible power is the theoretical maximum power that can be gained from a thermal system. The analysis has been applied to a combined cycle power plant, which is located in Bursa/Turkey. The effects of load and environmental temperature variations on costs are discussed and presented. Without considering the load effect, the cost of net electric power varied from 29 to 32$ MW−1 h−1, and about 40–45% of the cost of net electric power is composed of cost of irreversibility, while its 55–60% of it is the cost of reversible power. It is shown that the augmentation in the costs are not continuous with the environmental temperature decrease. In addition, there is an extremum at the temperature range between 5 and 10°C. Copyright © 2006 John Wiley & Sons, Ltd.

This paper describes a combined theoretical and experimental study of thermal comfort during the heating period inside an automobile. To investigate the effects of thermal conditions on the human physiology and thermal comfort during the heating period, temperature, humidity and air velocity were measured at a number of points inside the automobile, so thermal conditions were accurately determined. The human body was divided into 16 sedentary segments, and the change of temperature was observed both experimentally and theoretically. During transient conditions of the heating period, heat and mass transfer between the human body and the interior environment of an automobile were simulated by a computational model, and predictions were compared with the measured data. It is shown that there is a good agreement between the model predictions and experimental results. By means of the present model, the effects of the fast transient conditions of the heating period on the sensible and latent heat transfer from the body, body segments skin temperatures and thermal sensation were investigated in detail.

Historic structures and sites reveal the events, the problems, and the progress of the past. They present an opportunity to visualize the lives of the people before us. But every year some of these historic structures disappear, lost to future generations due to the ravages of fire. Cumalikizik, which is a unique example of the Ottoman Civil Architectural historic villages, is also under the fire risk. This paper expresses the present situation of the village, and provides a study in recognizing the fire problems in the Cumalikizik village. It also provides a guide for developing policies and procedures incorporating fire prevention and protection features into the structure and the village.

Bu çalışma, 03-06 Haziran 2002 tarihleri arasında Amsterdam[Hollanda]’da düzenlenen 47.International Gas Turbine and Aeroengine Congress and Exhibition’da bildiri olarak sunulmuştur. Disks rotating at different speeds are found in the internal cooling-air systems of most gas turbines. Defining F as the ratio of the rotational speed of the slower disk to that of the faster one then Gamma = -1, 0 and +1 represents the three important cases of contra-rotating disks, rotor-stator systems and co-rotating disks, respectively. A finite-volume, axisymmetric, elliptic, multigrid solver employing a low-Reynolds-number k-epsilon turbulence model, is used for the fluid-dynamics computations in these systems. The complete Gamma region, +1, is considered for rotational Reynolds numbers of up to Re-phi=1.25X10(6), and the effect of a radial outflow of cooling air is also included for nondimensional flow rates of up to C-w=9720. As Gamma-->-1, Stewartson-flow occurs with radial outflow in boundary layers on both disks and between which is a core of nonrotating fluid For Gammaapproximate to0, Batchelor-flow occurs, with radial outflow in the boundary layer on the faster disk, inflow on the slower one, and between which is a core of rotating fluid. As Gamma-->+1, Ekman-layer flow dominates with nonentraining boundary layers on both disks and a rotating core between. Where available, measured velocity distributions are in good agreement with the computed values.

In an absorption cooling system, simultaneous heat and mass transfer operations take place in the absorber and generator. The performance of an absorber is of paramount importance on the coefficient of performance and the manufacturing cost of an absorption machine. Increasing heat and mass transfer coefficients in an absorber decreases the heat transfer area of the absorber, as a result of this the cost of the system can be reduced. The absorption of water vapor in aqueous solutions of lithium bromide is modelled for a falling-film, vertical-tube absorber. Heat and mass transfer coefficients are determined by calculating temperature and concentration variations at the falling film in the absorber. Then mean Nusselt and Sherwood numbers are determined to see the changes in the heat and mass transfer. Subsequently, a modular computer program has been developed for absorption systems to simulate various cycle configurations and absorber parameters. So, the effect of hot water, chilled water and cooling water inlet temperatures on the coefficients of performance, Nusselt and Sherwood numbers and the surface area of the absorber are studied with the simulation program. The results can be used to optimise the commercial absorption chillers.

Numerical solutions of the Navier-Stokes equations have been used to model the flow and the beat transfer that occurs in the internal cooling-air systems of gas turbines. Computations are performed to study the effect of gap ratio, Reynolds number and the mass flow rate on the flow and the heat transfer structure inside isothermal and heated rotating cavities with peripheral flow of cooling air. Computations are compared with some of the recent experimental work on flow and heat transfer in rotating-cavities. The agreement between the computed and the available experimental data is reasonably good.

This paper presents a computational study of the flow and convective heat transfer in cylindrical reversed flow combustion chambers. The computations are performed using an elliptic solver incorporates the {kappa}-{epsilon} turbulence model. Heat production by combustion is simulated by adding heat generation source terms in the energy equation. And it is assumed that heat generation occurs only a section of the furnace. A number of different inlet conditions with different geometries are considered, and the changes of flow structure, temperature distribution, convective heat flux rate are presented and compared. The results show that, in general, heat transfer in the reversed flow combustion chamber can be improved by properly chosen geometry for the required output.

Automobile compartments arc exposed to unstable heat loads due to solar radiation, combined convection, conduction and radiation beat transfer through the cabin surfaces, air exchange and metabolic heat production of the occupants. In this study, a dynamic model of the heat loads that affect the thermal behaviour of the automobile compartment was developed in a Matlab-Simulink environment. Solar irradiation on cabin surfaces and thermal interactions between the driver and cabin interior can be calculated by the model. In order to determine mean radiant temperature and direct solar irradiation absorbed by the driver, view factors between the person and the interior surrounding surfaces were obtained by using a 3-D CFD model of cabin and driver. Experiments were also performed and the simulation results were compared with the measured and the obtained experimental data available in the literature. The effects of colour (white and black) and windows' optical properties (transmissivity, reflectivity and absorptivity coefficients) oil the thermal comfort were also investigated.

This paper describes a three-dimensional transient numerical analysis to determine the airflow and heat transfer characteristics inside the vehicle cabin during a heating period. A three-dimensional vehicle cabin including glazed surfaces and pertinent physical and thermal properties of the enclosure was modelled by using the real dimensions of a car. A virtual manikin was added to the model of the vehicle cabin to determine the heat transfer between the human body and the vehicle cabin ambient. The analysis takes into account all the possible thermal load of the cabin. Governing equations were solved by an implicit, time marching finite volume numerical scheme under varying inlet boundary conditions of the vehicle air conditioning system. The results of numerical calculations were in good agreement with the available experimental and theoretical data in the literature.