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- Kitap BölümüYalnız künye2018Scopus SJRQ3Contribution of the cogeneration systems to environment and sustainability
Kemal, Çomakli; Uğur, Çakir; Ayşegül, Çokgez Kuş; Erol, Şahin; Aloui, F; Dincer, I
The kind of energy that buildings need changes, like heating energy, cooling energy, electrical energy, and thermal energy for hot top water. Usually, the processes or systems that produce thermal energy emit pollutants while they produce heat because of the fossil fuels they use. A lower consumption of thermal energy will contribute not only to a reduction in the running costs but also in the reduction of pollutant emissions that contribute to the greenhouse effect and a lesser dependence of the hospital on the external power supply. Cogeneration or CHP (combined heat and power) is the system that produces power and usable heat simultaneously. Combined production of mechanical or electrical and thermal energy using a simple energy source, such as oil, coal, natural or liquefied gas, biomass, or the sun, affords remarkable energy savings and frequently makes it possible to operate with greater efficiency when compared to a system producing heat and power separately. Because of the life standard of humanity in new age, energy sources must be continually improved and updated. For this reason, the installation of a system for the simultaneous generation of electrical, heating, and cooling energy would be one of the best solutions if we want to have qualified energy and reduce investment and operating costs and meet ecological requirements. This study aims to bring out the contributions of cogeneration systems to the environment and sustainability by saving the energy and reducing the emissions.
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İncele - Derleme MakaleYalnız künye2018Scopus SJRQ1Green roofs and facades: A comprehensive review
Besir, Ahmet B.; Cuce, Erdem
Based on United Nations Environment Program (UNEP), building sector accounts for 40% of total energy consumption. In European countries, 36% of total greenhouse gas emissions is attributed to buildings. In this respect, green roofs are considered to be one of the most appropriate sustainable solutions to resolve the urban heat island-related issues. Roofs account for nearly 20–25% of overall urban surface areas. Energy saving, thermal insulation, shading and evapotranspiration features highlight the key role of green roofs in overall thermal performance of buildings and microclimatic conditions of indoor environments. Within the scope of this research, the concept of green roofs and facades is comprehensively analysed in a holistic and thematic way. Following a historical overview of the technology, the research is split into various subfields such as energy saving in buildings through greenery systems, multifunctional thermal benefits including evapotranspiration, thermal insulation, shading and thermal comfort features, evaporative cooling for reducing cooling demand and minimising wind driven convection losses. The results achieved from the literature survey clearly indicate that green roofs and facades are key solutions to mitigate building-related energy consumptions and greenhouse gas emissions. According to the previous works, heat flow through the building roofs in summer can be reduced by approximately 80% via green roofs. The green roofs are reported to consume less energy in the range of 2.2–16.7% than traditional roofs during summer time. A similar tendency is observed for the winter season depending on regional and climatic conditions. The temperature difference between conventional and greens roofs in winter is found to be about 4 °C, which is remarkable. Energy demand of buildings in summer is highly dependent on the plant intensity as it is reported to be 23.6, 12.3 and 8.2 kWh/m2/year for extensive, semi-intensive and intensive greenery surface, respectively. Greenery systems are also capable of providing thermally comfortable indoor and outdoor conditions. It is underlined that the annual average accumulation of CO2 reaches the level of 13.41–97.03 kg carbon/m2 for 98 m2 of vertical greenery system. The results of this research can be useful for dwellers, builders, architects, engineers and policy makers to have a good understanding about the potential of green roofs and facades to mitigate building-related energy consumptions and carbon emissions in a renewable, sustainable, energy-efficient and cost effective way.
AtıfScopus547WoS435OpenAlex617İncele - MakaleAçık Erişim2017Scopus SJRQ1Thermal regulation impact of green walls: An experimental and numerical investigation
Cuce, Erdem
Green walls can be basically defined as climbing plants grown either directly against, or on support structures integrated to external building walls. Similar to other types of green infrastructure, they are in the centre of interest owing to their remarkable benefits such as reducing internal building temperatures, mitigating building energy consumption and facilitating urban adaptation to a warming climate. In this research, thermal regulation feature of green wall systems is experimentally and numerically investigated through a case study conducted in the Jubilee Campus of University of Nottingham. Internal wall temperatures are measured time-dependently for different cases and the results are compared with those of ordinary walls for a reliable and realistic approach. Different sky conditions are also considered within the scope of this research as an independent variable. Experimental results are verified by numerical models carried out in Ecotect. The results reveal that an average of 2.5 °C reduction in internal wall temperature can be achieved via green walls with about 10 cm thick climbing vegetation of Hedera helix, which is very promising.
AtıfScopus168WoS138OpenAlex178İncele - MakaleYalnız künye2017Scopus SJRQ1Role of airtightness in energy loss from windows: Experimental results from in-situ tests
Cuce, Erdem
The rate of air leakage related energy loss from glazed areas is unequivocal especially in older and poorly installed windows. Therefore, in this research, a comprehensive experimental investigation is done to analyse the importance of air leakage on overall heat transfer coefficient (U-value) of conventional air filled double glazed windows. The tests are conducted in a typical UK dwelling of Nottingham fitted with traditional air filled double glazed windows. One sash of the test window is sealed internally with a special transparent cover to provide excellent airtightness whereas the second window sash is left as it is to represent the ordinary case. The experiments are conducted in April 2016, and dynamic co-heating test methodology is applied to evaluate the rate of enhancement in the U-value of airtight window sash. The results indicate that the airtight window sash has a notably lower U-value compared to the ordinary window sash due to the impact of airtightness and reverse heat flux during noon time owing to the greenhouse effect between transparent cover and internal glazing. The overall U-value of ordinary window sash is found to be 2.67 W/m2K, whereas it is 1.79 W/m2K for airtight window sash. It is observed that about 33% of reduction in heat losses can be achieved via airtight windows.
AtıfScopus60WoS59OpenAlex75İncele - MakaleAçık Erişim2016Scopus SJRQ1Exergetic interrelation between an heat pump and components
Çakır, Uğur; Çomaklı, Kemal
In this study, the relation between the exergetic performance of the heat pump and its components are investigated experimentally by using an air to water heat pump. Moreover, the effects of the working conditions of the components on the exergetic performance of the system are exposed and discussed. An experimental air to water heat pump system was designed and built. The results were evaluated by comparing the components and heat pump according to their performances. 33–45% of the all destructed exergy of the heat pump system comes into existence in the compressor. The contribution of the condenser to the total exergy destruction rate of the heat pump is between 23% and 34%. Contribution of the compressor to the exergy destruction rate of heat pump decreases with an increase in the air temperature and it increases with a decrease in the air mass flow rate. Contribution of the compressor to the exergy destruction rate of heat pump decreases with an increase in the air temperature and it increases with a decrease in the air mass flow rate. In terms of exergetic performance of the heat pump, the importance and priority of the components vary with the heat source thermal conditions.
AtıfScopus15WoS14OpenAlex16İncele - MakaleYalnız künye2016Scopus SJRQ1Energy saving potential of heat insulation solar glass: Key results from laboratory and in-situ testing
Cuce, Erdem; Cuce, Pinar Mert; Young, Chin-Huai
HISG (heat insulation solar glass) is a recently developed multi-functional glazing technology to mitigate energy consumption of buildings. HISG can generate electricity similar to conventional PV (photovoltaic) glazing products when exposed to sunlight, however it differs from them by having some extraordinary characteristic features such as thermal insulation, which is competitive with Argon filled triple glazed windows, acoustic comfort, remarkable energy saving potential and self-cleaning ability owing to TiO2 nano coating. Within the scope of this research, latest results from laboratory and in-situ testing of HISG are presented in terms of its key role in mitigating heating and cooling demand of buildings as well as clean energy generation. Lighting and thermal comfort related parameters such as shading coefficient, UV, IR and visible light intensity are also investigated through the tests conducted in real operating conditions. It is achieved from the results that instant electricity generation of HISG is 16% higher than that of standard PV glazing owing to its nano layer reflective film. Shading coefficient of HISG is only 0.136, which provides almost 80% reduction in solar heat gain compared to ordinary glazing. Indoor air temperature measured from HISG test house in summer time is very close to the ambient temperature, whereas it is found to be 14.7 °C higher in ordinary glass test house due to greenhouse effect. Annual heating and cooling demand tests indicate that HISG provides 38 and 48% energy saving in heating and cooling season, respectively.
AtıfScopus52WoS46OpenAlex56İncele - Kitap BölümüYalnız künye2014A solar energy calculation study for the buildings in bayburt in order to get optimum benefit from the sun directly
Çakır, Uğur; Şahin, Erol
This study is a research made on evaluating solar energy utilization rates of the buildings and residences which are under the climatic and meteorological conditions of Bayburt. In the scope of this study, with the aim of enabling them to benefit from solar energy at the maximum level, a numerical modeling study in which we could determine the most suitable directions, shapes, and sizes of the buildings that would be built in Bayburt was carried out. Although the modeling was applied for sample buildings that have specific sizes and shapes and some results were obtained, this modeling can be used for other buildings which have different shapes and the most suitable direction and location designation that can be done. In the solar energy analysis made for the buildings, a year time was divided into four different periods. Related evaluations were made by taking into account that the building should be in shape and orientation which takes the maximum and minimum radiance in the summer and winter. Basic parameters were determined as azimuth angle, the ratio of the building length to its width, and the total periodical radiance that the building takes.
- MakaleAçık Erişim2013Scopus SJRQ2Energetic and exergetic comparison of air to air and air to water heat pumps according to evaporator conditions
Çomakli, Kemal; Çakir, Uǧur; Şahin, Erol; Kuş, Ayşegül Çokgez
This paper presents an experimental energetic and exergetic comparison for a heat pump system that can be run in different modes as air to air and air to water. Components of the heat pump do not change when the running mode changes, except for the condenser. This means that some external and internal effects (like compressor type, pipe lines) that can affect the system performance will be the same for each running mode. The comparison which was made in this study demonstrates which system leads to an efficient conversion and supply of energy and exergy. In the analysis, four balance (mass, energy, entropy and exergy) equations are applied to the system for the two modes. Exergy and energy efficiency values for both systems are given, while exergy destructions in each of the systems are determined and presented. It is seen that the heat pump unit which has the highest COP value is the air to air type (3.45-3.8); second is the air to water type (3.35-3.41). The exergy efficiency of the air to air heat pump (29-32%) is higher than the exergy efficiency of the air to water type heat pump (24.1-25). Ranking of the exergy destruction rates of the two heat pump types from high to low is as follows: air to air and air to water.
AtıfScopus5OpenAlex5İncele - BildiriYalnız künye2012Scopus SJRQ1The role of cogeneration systems in sustainability of energy
Çakir, Uǧur; Çomakli, Kemal; Yüksel, Fikret
Cogeneration system (CHP) is one of the ways to save the energy and use the energy efficiently. When compared to separate fossil-fired generation of heat and electricity, CHP may result in a consistent energy conservation (usually ranging from 10% to 30%) while the avoided CO 2 emissions are, as a first approximation, similar to the amount of energy saving. In terms of sustainability, one of the primary considerations is energy efficiency. Sustainable energy is considered as a kind of energy which is renewable and continuous, meaning that the use of such energy can potentially be kept up well into the future without causing harmful repercussions for future generations. In this study, environmental benefits and sustainability aspects of cogeneration systems and importance of those systems to the use of sustainable energy are underlined. To support this idea, first we have referred some scientific studies previously made on cogeneration systems and then we have used our own case study. The case study made on gas engined cogeneration system was applied for a hospital to show the sustainability aspects of cogeneration systems.
AtıfScopus115WoS97OpenAlex135İncele