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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%.

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.

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

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.

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.

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.

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

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.

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.

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.

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.