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In this paper, a detailed combined 1-D model of HVAC systems of a vehicle were developed by using the LMS imagine LAB AMESIM software package. The numerical simulations were considered for soaking and cool down analysis under different environmental conditions. The thermal performance of different refrigerants as R-134a and R-1234yf were evaluated in terms of thermal performance and energy consumption. According to the soaking simulation results, the cabin air temperature values ranged from 49?C to 57?C in general. The maximum increase in cabin air temperature value was about 22?C obtained for 1000 W/m2 solar load. The total time until reaching the steady-state conditions for a target temperature value (23.5?C) was different for all simulations. The total time was calculated as 910 seconds for 1000 W/m2 solar load by using R-134a refrigerant loop. The results also showed that although the thermal performance of R-134a was slightly better, R-1234yf can be used due to its environmental properties with acceptable performance. The calculated COP values during cooldown analysis were ranged from 1.71 to 4.52 in general. The minimum value was obtained for the cases which had a maximum solar load and higher cabin interior temperature values. The calculated temperature data for soaking and cool down analysis were in good agreement with the reference data presented in this study. These numerical results are very important for reducing the thermal load of the vehicle cabin considering energy consumption of the HVAC system for different thermal conditions.

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.

In this study, the combined power and refrigeration cycles driven by low-grade thermal energy are evaluated. An organic Rankine cycle (ORC) and a vapor compression refrigeration cycle (VCRC) are li...

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%.

Elektronik ekipmanların çalışma performansını olumsuz etkileyen fazla ısının atılması gelişen teknoloji, artan güç ve küçülen boyutlar dolayısıyla önemli bir teknolojik problemdir. Bu kapsamda mini kanallı sıvı soğutmalı soğutucu bloklar üzerine araştırma çalışmaları giderek artmaktadır. Soğutucu blokların yüksek ısı transferi performansına sahip olması beklenirken işletim maliyetleri açısından basınç düşümünün en az seviyede olması istenmektedir. Bu durum soğutucu bloğun tasarımında geometrik yapının istenen performans kriterlerine göre optimizasyonunu gerektirmektedir. Bu çalışmada 100W/cm2 ısı akısı üreten bir yonganın soğutulması için kullanılacak 20mm x 20mm taban yüzey alanına sahip mini kanallı su soğutmalı bir bloğun tasarımında yüksek ısı transferi ve düşük basınç kayıpları için üç farklı malzeme ile optimizasyon çalışmaları gerçekleştirilmiştir. Çalışmada Taguchi ortogonal matrisinden yararlanılarak farklı malzemeler ve farklı boyutlarda tasarlanan mini kanallı soğutucunun performansı Hesaplamalı Akışkanlar Dinamiği (HAD) kullanılarak hesaplanmıştır. Optimizasyon değerlendirme ölçütü olarak basınç düşümü ve tabanda oluşan maksimum sıcaklığın en düşük olması göz önünde bulundurulmuştur. Her iki ölçütün birlikte değerlendirilmesi için Çok Yanıtlı Taguchi Analizinden yararlanılmıştır. Sıcaklık ve basınç kaybı değerlerine farklı ağırlık değerleri verilerek bulunan sonuçlar karşılaştırılmış ve yorumlanmıştır.

In this study, a PV/Wind hybrid power generation system was studied with using meteorological data of Bursa province. Two specific years (2011, 2014) were chosen for the dynamic simulations. The designed hybrid system consists of PV panels and a wind turbine. The outcome of the study shows that with the proposed 1 MW PV + 2 MW wind turbine system, it is possible to generate enough electricity to compensate the annual electricity requirement of 450 households which can be considered as a small district area. Levelized cost of energy is found a value between $ 0.413-0.568/kWh. PBP of the system is found a value around 20 years. It was concluded that it is essential to offer adequate incentives for renewable-based power applications to make them economically beneficial.

Gas turbines are widely used in the energy production. The quantity of the operating machines requires a special attention for prediction of power production in the energy marketing sector. Thus, the aim of this paper is to support the sector by making the prediction of power production more computable. By using the data from an operating power plant, correlation and regression analysis are performed and linear equation obtained for calculating useful power production vs atmospheric air temperature and a novel method, the gas turbine degree day method, was developed. The method has been addressed for calculating the isolation related issues for buildings so far. But in this paper, it is utilized to predict the theoretical maximum power production of the gas turbines in various climates for the first time. The results indicated that the difference of annual energy production capacity between the best and the last province options was calculated to be 7500 MWh approximately.

This paper presents an approach to estimate the temperature on the friction surface of a dry clutch. The study comprises both experimental measurements and transient thermal numerical analysis of heavy duty truck clutches for the successive engagements on a slope road. Compared to previous mathematical models in the literature; pressure plate surface convection coefficient, energy dissipation, engagement duration and variation of the clutch housing air temperature were obtained on the basis of experimental data and have been applied as input in the 3D clutch transient thermal finite element analysis. Simulation results show that the design of clutch plate has a significant effect on the temperature rise at the friction surface.

In this paper, the thermal performance of a liquid cooling block designed for automotive lighting components integrated with high power Light Emitting Diode (LED) was investigated, numerically and experimentally. Single and multi-chip on the printed circuit board (PCB) were selected to get comparative numerical results in view of temperature differences on PCB surfaces for automotive lighting systems. In the numerical simulations, three-dimensional Computational Fluid Dynamics (CFD) model with natural convection effects was developed for predicting temperature distributions of PCB surfaces. For this purpose, the single and multi 5-cell high power LED lighting system with cooling block design were modeled. On the other hand, the effect of the aspect ratio of cooling channel and block material on the thermal performance of circuit boards with single and multi-chip was also investigated numerically due to needing for weight reduction for automotive lighting applications. From the results, higher temperature gradients were measured and predicted near the LED chip due to the heat production of LEDs. Block material had little impact on the LED temperature but using different materials aid to reduce block weight for automotive application. From the comparison of the numerical data obtained for each PCB, the LED junction temperature was similar therefore same cooling block design can also be used for multi-LED chip applications for Automotive Lighting Systems. This Multi LED design using with liquid cooling block gives more opportunities for future head and rear lamp applications of vehicles.

Energy demand of countries changes depending on many socioeconomic factors like their population, the level of social and economic development, industrialization, urbanization, and technological development. In the past decade, economic growth and social development in our country has led to increased energy consumption. Accordingly, the amount of energy needed must be provided to realize the economic growth and social development in time, satisfactory, uninterrupted and taking into account the environmental impact. For this reason, it is necessary to determine and prioritize alternative energy strategies. This study used 1970–2011 energy data from Turkey's Energy-Balance Tables and developed long-term energy-demand projections for Turkey as a Long-range Energy Alternatives Planning System Program. Two scenarios for Turkey's energy demand were created and their results evaluated. In addition, scenarios were created such that the renewable energy resources' ratios, which are solar, wind, hydro, and geothermal energy, etc., are increased in total energy supply, and their results were evaluated for energy demand and for electricity generation.

Existing buildings consume more energy than the new ones and building energy efficiency retrofit has a major effect in order to achieve sustainable building targets. Retrofitting not only creates possibilities to reduce energy consumption and carbon dioxide emissions of all buildings but also improves occupants' health and thermal comfort. Making a decision for a retrofit action is very important in order to select the most appropriate, energy-efficient and cost-effective scenario for the building. The industrial sector is one of the largest energy consumers with 25.6% of the overall energy consumption in Europe in 2012. However, conducted energy retrofit studies have mainly focused on domestic buildings so far. The focus of this chapter is a literature review of energy-efficiency retrofits and presentation of an approach to find the most convenient, energy-efficient and investor-friendly retrofit scenario for an industrial building. Eventually, the idea is to be able to convince building owners and investors to renovate with energy-saving solutions. In this chapter, energy consumption of a cement factory during its operation, before and after the energy retrofit application, is examined. Results from the analysis ensure that energy-efficiency refurbishment helped to reduce energy consumption of the building and eventually decreased operational costs and carbon dioxide emissions in a very short payback period. Reduction in energy consumption in the building led to an energy cost savings of $169,725 per year. Carbon dioxide emissions decreased by 87%.

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.

Nowadays, new developments in the properties of insulation materials used in buildings and international regulations lead to the use of more efficient heating systems. On the other hand, the increased energy efficiency of modern buildings makes necessary the use of low-temperature heating systems. Thus, we need to design a new generation of energy-efficient radiators which have a low capacity of water volume and low weight compared to conventional radiators. Moreover, the standards defined for the testing procedures of the thermal output of steel panel radiators have been changed depending on the objectives of energy efficiency. In this context, a detailed thermal analysis of a panel radiator should be performed to meet the needs for these objectives. Three-dimensional computational fluid dynamics (CFD) is a useful tool for the thermal analysis of a steel panel radiator. In this study, three-dimensional numerical calculations of the thermal output of a steel panel radiator, in accordance with TS EN442, was performed by using CFD analysis based on the finite volume method. The numerical calculations were performed under steady-state conditions. The results obtained from the numerical simulations were in good agreement with the experimental data available in the literature.

Nowadays the focus of the power sector is on renewable energy sources. Even so, in Turkey, the most preferred power plants are still co-generation power plants. Considering installed power, gas turbine power plants are the most used type. In gas turbine power cycles, both power and efficiency are highly affected by atmospheric temperature. In this study, the degree-day method is used to expose the variation of the electric power of a gas turbine with respect to atmospheric conditions. The installed capacity of the gas turbine is 237 MW. The operating data were supplied by Ovaakca Power Plant Administration of Bursa/Turkey. In this paper it is indicated that, for a 45 °C increment of atmospheric temperature, mass flow through the compressor at a unit time decreases by about 85.2 kg. Therefore, the compression work decreased by about 11.45 %. In addition, by means of the atmospheric temperature increment, both the total energy input via natural gas and intake airflow rate were decreased by 17.1 % and this resulted in a reduction in net electric power production.

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.