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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.

The paper presents an investigation of local thermal comfort of passengers in a railway vehicle. The railway vehicle model includes five different parts called modules, and each module had different properties such as passenger capacity and seating arrangement. A virtual manikin model was developed and added to the numerical model which includes convection and radiation heat transfer between the human body and the environment. The numerical simulation was conducted according to the EN 14750-1 standard describing the thermal comfort conditions for different climatic zones. Two different cases were performed for steady-state conditions. Meanwhile, measurements were taken in a railway vehicle cabin to validate the numerical simulation, and the numerical results were in good agreement with the experimental data. It is observed that the local heat transfer characteristics of the human body have significant importance for the design of an effective heating, ventilation, and air conditioning (HVAC) system because each module had different heat transfer and air flow characteristics. It is also shown that the thermal sensation (TSENS) index helps railway vehicle HVAC researchers to determine the reasons for discomfort zones of each occupant. Another important result is that using a single air flow channel did not meet the thermal comfort demands of all passengers in this railway vehicle. Therefore, multiple air flow channel design configurations should be considered and developed for these vehicles. Local thermal comfort models allow HVAC systems to achieve better comfort conditions with energy saving. The numerical model can be used for effective module design, including seating arrangements, to achieve better thermal comfort conditions.

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%.

The goal of this study is to investigate comparatively the performance of an integrated cooling system comprised of an adsorption cooling cycle (ADC) and a vapor cooling cycle (VCC) with two different configurations, namely (cascaded and serial connected evaporators). The ADC chiller relies on the thermal compressor with two adsorption beds, which use three different adsorbents (RD silica gel, RD silica gel 2060, and silica gel- LiCl) and water (adsorbate) as a working pair separately. The thermal compressor operates by outside waste or solar-based thermal sources that have low-level temperatures below 100 °C. R152A was selected for the VCC chiller. This article pays particular attention to evaluating the ADC adsorbents and (ADC-VCC) connection configurations based on the first and second law of thermodynamics. The investigations have been implemented at different ADC evaporator temperatures. The effect of adsorption cycle time and ambient temperature on the overall coefficient of performance were also investigated and discussed for both configurations. Furthermore, the ADC and VCC coefficient of performances and the performance ratio (PR) were investigated at different ADC evaporator temperatures. The relation between the adsorbent mass and the cooling load was also discussed in this paper.

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.

Klimatik kontrollü treyler yaş meyve sebze, dondurulmuş ürün ve hayvansal gıdaların taşımacılığında önemli rol oynayan araçlardan biridir. Bu treyler bir soğutucu ünite, izolasyonlu üst yapı ve şasiden oluşmaktadır. Bu çalışma kapsamında genellikle dondurulmuş ürünlerin taşınmasında kullanılan ağır izolasyonlu sınıftaki bir treyler üzerinde çalışılmıştır. Çalışmanın temel amacı kabin içi soğutma performansının iyileştirerek taşınan ürünlerin kalitesini arttırmak ve soğutma yüklerini azaltarak yakıt tasarrufu sağlamaktır. Bu amaç doğrultusunda standart olarak sunulan araç içerisindeki hava akışı modellenmiş ve görülen eksiklikleri giderecek bir tasarım yapılmıştır. Daha sonra yapılan analizler gerçek araç modelleri üzerinde yapılan testlerde doğrulanmıştır. Son olarak ilk yapılan tasarımda iyileştirme yapılmış ve farklı bir hava dağıtım metodolojisi düşünülmüştür ve modellenmiştir. Sonuçlar birbiri ile kıyaslanmış ve araç içi hava akışında elde edilen iyileştirmeler gösterilmiştir. Çalışma sonunda, havanın yeni tasarlanan kanallar vasıtasıyla aktarılması sayesinde soğuma performansının arttığı ve araç içi sıcaklık dağılımının homojen hale geldiği görülmüştür.

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.

The aim of this study is to assess the state-of-the-art situation of mechanical compressors with thermal compressor systems in combined cooling systems and their ability to provide the required cooling effects with lower energy consumption than traditional cooling systems. The integrated systems have various advantages such as a broad temperature range, low energy consumption, and more flexibility in operating conditions. A comprehensive review of thermal–mechanical combined cooling systems is presented in terms of its principles, applications, different configurations, and various heat source systems. Two types of thermal compressor systems are included in this study. The first one is the absorption system that uses a liquid–vapor working pair in its thermodynamic cycle. Additionally, the second type is the adsorption system that utilizes a solid–vapor working pair in its thermodynamic cycle. It is concluded that continuing technological innovations are vital for sustainable cooling. Technological developments can lead to cooling that is both inexpensive and energy-efficient.

In this study, a numerical simulation model and an analytical method are introduced to evaluate the particle collection efficiency and transport phenomena in an electrostatic precipitator (ESP). Several complicated physical processes are involved in an ESP, including the turbulent flow, the ionization of gas by corona discharge, particles’ movement, and the displacement of electric charge. The attachment of ions charges suspended particles in the gas media. Then, charged particles in the fluid move towards the collection plate and stick on it. The numerical model comprises the gas flow, electrostatic field, and particle motions. The collection efficiency of the wire-plate type ESP is investigated for the particle diameter range of 0.02 to 10 µm. It is observed that electric field strengths and current densities show considerable variation in the solution domain. Meanwhile, changing supply voltage and charging wire diameters significantly affect the acquired charges on the electrostatic field and particle collecting efficiencies. Simultaneously, the distance between the charging and collecting electrodes and the main fluid inlet velocity has an important effect on the particle collection efficiency. The influence of the different ESP working conditions and particle dimensions on the performance of ESP are investigated and discussed.

This research work presents a comparative thermal performance assessment of the laminar flow cooling blocks produced for automotive headlight assembly using a high power Light Emitting Diode (LED) chip. A three-dimensional numerical model with conjugate heat transfer in solid and fluid domains was used. Laminar flow was considered in the present analysis. The validation of the numerical model was realized by using the measured data from the test rig. It was observed that substantial temperature variations were occurred around the LED chip owing to volumetric heat generation. The cooling board with lower height performs better thermal performance but higher pressure drop for the same mass flow rates. The cooling board with the finned cover plate performs better thermal performance but results in an increased pressure drop for the same mass flow rates. Increasing the power of the LED results in higher temperature values for the same mass flow rates. The junction temperature is highly dependent on the mass flow rates and LED power. It can be controlled by means of the mass flow rate of the coolant fluid. New Nusselt number correlations are proposed for laminar flow mini-channel liquid cooling block applications.

The organic Rankine cycle (ORC), which generates electric energy using low temperature heat sources, is a promising technology in energy production sector. The ORC, which uses an organic fluid with its lower boiling point and higher vapor pressure than water-steam as a working fluid. The thermal efficiency of an ORC showes the performance of system, depends on system compenents, working fluid and operating conditions. This paper presents an thermodynamics examination of basic ORC and regenerative ORC for waste heat recovery applications using dry organic fluids. R113, R114, R227ea, R245fa and R600a with the boiling points from -16 oC to 48 oC are selected in the analyses. The relationships between the ORC's performance parameters for basic and regenerative technologies and the properties of working fluids are evaluated based on various turbine inlet pressure values. Results show that regenerative ORC has higher thermal efficiency compared with basic ORC. Also, the thermal efficiency increases with the increment of the turbine inlet pressure for both basic ORC and regenerative ORC.

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.

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.

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.

In this paper, thermal and hydraulic analysis of a dual-separated cooling channel was performed for the cooling applications of different automotive lighting systems. A single LED and multi-LEDs were considered to evaluate the thermal and hydraulic performance as well as the lighting properties of automotive headlights. The detailed hydraulic analysis was theoretically evaluated for developing laminar flow to get higher thermal performance with less pumping power. The theoretical and simulation results for the dual-separated cooling channel were compared and discussed. Unlike the constant properties were used in the current literature, thermal analysis with temperature-dependent properties was performed to estimate Nusselt number preciously for dual-separated cooling channels. The temperature measurements were also performed in the experimental study to compare the numerical results. The light output parameter of the LEDs depends on junction temperature, it was found that the increase in light output by using a dual-separated cooling channel was about 10% for all cases. Otherwise, higher junction temperature values lead to a reduction in operating efficiency. The top copper surface temperature drop was higher than 50%, and the junction temperature had been reduced by 36% to ensure the desired operating conditions of the automotive lighting system.

This study presents the effects of duct design on thermo-fluidic characteristics of ventilated clutch pressure plate via validated numerical model. Two different duct designs are considered. Moreover, variation of duct width and airfoil shaped duct designs are investigated. Compared to non-ventilated conventional clutch pressure plate, results show that implementing duct shape enhances the overall cooling performance by up to 154% at idle speed 550 rpm, 137% at 1200 rpm, and 142% at 2000 rpm. Once only the duct shapes are considered, it is found that the variation of inlet and outlet duct width has negligible effect on overall cooling performance. Further, radial airfoil shaped duct design shows the best cooling performance in overall among all duct shapes, and enhances the overall cooling performance by up to 11% at 550 rpm idle speed compared to non-airfoil radial duct design. In addition, implementation of ventilated design results weight reduction up to 25%. Heat transfer enhancement mechanisms clarified in the present study are helpful to motivate further innovative lightweight solutions in order to overcome the challenges related to the recent CO2 regulation for Heavy Duty Vehicles.

This article aims to analyze comparatively the performance of a combined refrigeration system consists of an upper section (adsorption chiller) and a lower section (vapor compression chiller (VCC)). The arrangement of the adsorption cooling chiller (ACC) depends on two adsorption beds that use silica gel/water as a working pair. The beds are driven by heat comes from outside heat sources with low-grade temperatures ≤100 °C. Whereas in the bottom section, different types of refrigerants (R410A, R152A, R1234yf, R1270, and R32) have been utilized to be driven by the mechanical compressor. This paper focuses on the evaluation of the refrigerants in VCC and the working pair in ACC by means of coefficient of performance (COP) and energy-saving ratio (ES) in this refrigeration system. The computed results reveal that the refrigerants show the same behavior while calculating the COP of the combined system and the VCC in the combined system, with the high values reached up to 0.5 and 8.8 for R152A, respectively. Meanwhile, the energy-saving reached up to 65.3%. The increase ratio (IR) of the COP of the VCC is also calculated with the highest value reached up to 188%. The effects of the ambient air temperature, the heat source temperature, the cycle time and the evaporation temperature on the system performance and the required mass of adsorbent in the adsorption beds are investigated for the design of ACC-VCC combined system.

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.

Recent studies show that demand for green buildings with minimal environmental impact is increasing. Among the buildings in anywhere, existing buildings consume more energy than new ones. Because of that, building energy efficiency retrofit plays a very important role for achieving sustainable building targets. In addition to creating possibilities to reduce energy consumption, retrofitting also improves occupants’ health and comfort. Tourism sector is one of the largest energy consuming sectors in the world. However conducted energy retrofit studies mainly focused on domestic buildings so far. The focus of this paper is to make a literature review of energy efficiency retrofits and present an approach to find the most appropriate, energy efficient and cost effective way renovate a hotel building. In this paper, a hotel building is energy efficiently retrofitted according to the TSE Green Building Certificate standards. Results from the analysis ensure that energy efficiency retrofit, helped to reduce energy consumption of the building and decreased in operational costs and CO2 emissions.

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.

Relatively low-temperature renewable energy and industrial waste heat resources can be used to configure a solid adsorption refrigeration or cooling system that has no destructive or harmful effects on the environment. Therefore, such a system has attracted much interest for researchers across the world. The physical adsorption phenomenon is a reversible process realized mainly within the cavities and pore surfaces of the solid adsorbent. It is known that the adsorption characteristics of an adsorbent–adsorbate pair are strongly related to variations in temperature and pressure. The objective of the current study was to investigate experimentally the adsorption characteristics of the refrigerants R134a and R404a onto activated carbon. An experimental setup working with a constant-volume variable pressure method was used in the experimental measurements. During the adsorption processes, data from experimental isotherms were obtained at different constant temperatures ranging from 293K to 323K while pressure varied from 0 to about 500 kPa. These data are useful for designing adsorption cooling and refrigeration systems. Commercially available granular and pellet-type activated carbon (AC) samples were considered in this work. Experimental measurements were performed for four different adsorbent–adsorbate pairs obtained by combining the adsorbents (granulated AC and pellet AC) and adsorbates (R134a and R404a). Adsorption parameters were evaluated from the measured isotherms to obtain correlations in the form of the Dubinin–Astakhov equation. The pressure and temperature dependence of the isosteric enthalpies of adsorption were computed by evaluating the measured data and the derived equations. Furthermore, the parameters of the correlations are provided for each adsorbent–adsorbate pair. Results are compared and discussed in detail.

In this study cooling of a LED unit with heatsink and liquid cooling block which is used in automotive head lamp applications has been investigated numerically and experimentally. Junction temperature of a LED which is cooled with heatsink and liquid cooling block obtained in the experiment. 23°C is used both in the simulation and the experiment phase. Liquid cooling block material is choosed aluminium (Al) and polyamide. All tests and simulation are performed with three different flow rate. Temperature distribution of the designed product is investigated by doing the numerical simulations with a commercially software. In the simulations, fluid flow is assumed to be steady, incompressible and laminar and 3 dimensional (3D) Navier-Stokes equations are used. According to the calculations it is obtained that junction temperature is higher in the heatsink design compared to block cooled one. By changing the block material, it is desired to investigate the variation on the LED junction temperature. It is found...

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%.

In this study, the gas turbine cycle of Ovaakca power plant that is located in Bursa, Turkey was analysed. The aim of the study is to determine the use of an ice thermal energy storage system for the 239 MW-powered gas turbine cycle. The performance of the system was investigated for full-load conditions. Energy and exergy analysis were performed by using last decade’s meteorological weather data. The results showed that utilizing an ice thermal energy storage system can boost the net power up to 12.60%.

For removal of Cu(II) ions from aqueous solution, a novel composite was prepared from 1-vinyl imidazole and sepiolite by the technique of in-situ polymerization. Adsorption of Cu(II) ions from aqueous solution onto Sepiolite-Poly(vinylimidazole) composite has been studied at 277, 298, 318, and 338 K and the experimental data were analyzed using fourteen isotherm models. The determination coefficients (R2) were determined for each isotherm analysis. The determination coefficients demonstrated that in general the accuracy of models to fit experimental data improves with the number of parameters. The Langmuir model provided the best fit to the experimental data among the two-parameter isotherms. The Toth model provided the best fit to the data among the three-parameter models. Adsorption isotherm modeling shows that the interaction of Cu(II) with Sepiolite-Poly(vinylimidazole) composite surface is localized to monolayer sorption and adsorption is an endothermic process. Additionally, adsorption experiments showed that Sepiolite-Poly(vinylimidazole) composite can be used as an effective adsorbent for the removal of Cu(II) ions from aqueous solution.

The aim of the paper is to present a three dimensional transient cooling analysis of an automobile cabin with a virtual manikin under solar radiation. In the numerical simulations the velocity and the temperature distributions in the automobile cabin as well as around the human body surfaces were computed during transient cooling period. The surface-to-surface radiation model was used for calculations of radiation heat transfer between the interior surfaces of the automobile cabin and a solar load model that can be used to calculate radiation effects from the sun's rays that enter from the glazing surfaces of the cabin was used for solar radiation effects. Inhomogeneous air flow and non-uniform temperature distributions were obtained in the automobile cabin and, especially in ten minutes of cooling period, high temperature gradients were computed and measured and high temperature values were obtained for the surfaces which were more affected from the sunlight. Validations of the numerical results were performed by comparing numerical data with the experimental data presented in this study. It is shown that the numerical results were good agreement with the experimental data.

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.

The aim of this study is to evaluate effect of solar radiation on thermal comfort in an automobile during cooling period with experiments. High cabin interior temperature, especially in summer months, causes discomfort for driver and the passengers. In the study, ambient temperature, relative humidity, mean radiant temperature and mean skin temperature of the driver inside the automobile cabin during cooling period for same ventair velocities with different solar radiation values were measured in a parked car. Subjective survey was performed during the experiments to the driver. Experiments were held under real conditions and the results were compared with answers taken from the subject and discussed. Adequate thermal comfort conditions were not obtained for high solar radiation values but it was found that thermal comfort conditions inside the cabin were quite acceptable for low solar radiation values., Bu çalışmanın amacı güneş ışınımının soğutma sürecinde otomobil kabini içerisindeki ısıl konfor koşullarına olan etkisinin deneysel olarak incelenmesidir. Özellikle yaz aylarında güneş ışınımından kaynaklanan yüksek kabin iç ortam sıcaklığı sürücü ve yolcuların kendilerini rahatsız hissetmelerine neden olmaktadır. Çalışmada, soğutma sürecinde park edilmiş bir araba içerisinde aynı menfez hız düzeyinde değişik güneş ışınımı değerleri için yapılan deneylerde, kabin iç ortam sıcaklığı, bağıl nem, ortalama ışınım sıcaklığı ve sürücüvücut ortalama sıcaklığı değerleri ölçülmüştür. Deney sırasında sürücüye nesnel anket uygulanmıştır. Deneyler gerçek koşullar altında gerçekleştirilmiş olup, elde edilen sonuçlar sürücünün nesnel anket sorularına verdiği cevaplar ile karşılaştırılmış ve tartışılmıştır. Yüksek güneş ışınımı değerlerinde otomobil içerisinde uygun ısıl konfor koşulları sağlanamamış ancak düşük güneş ışınımı değerlerinde kabin içi ısıl konfor koşulları açısından oldukça uygun bulunmuştur.

A healthy and comfortable indoor environment is the most basic requirement of human beings. The importance of indoor air quality has been increasing day to day. Although ventilation systems have an essential role in improving indoor air quality, it is inevitable to clean the particulates, microorganisms and pollutant gases in the outside fresh air before being transferred to the indoor environment. Electrostatic precipitators are commonly used for collecting particles mostly in industrial plants. This paper presents a review of electrostatic filtration technology. In this study, theoretical and technical developments of electrostatic precipitators, design parameters that effect filtering performance, advantages, challenges, and limitations are discussed.

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.

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.

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.

Determination of heat transfer rate and Nusselt number in the thermal entry region in ducts is considered. Alternative relations are derived to calculate the rate of heat transfer and Nusselt number. An approximate equation is proposed for the calculation of mean and local Nusselt number in all range of the axial distance in the thermal entry region in ducts with constant surface temperature. And the use of this correlation is extended to predict mean and local Nusselt number in the thermal entry region in tubes with constant wall heat flux

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.

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.