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[EN] The objective of this article is to compare the behaviour of the most representative domestic hot water systems (DHW) in single-family buildings. The study evaluates the energy consumption, equivalent CO2 emissions and cost for each system over a 15-year life period. This analysis is carried out in four cli- matic zones across Europe to observe the influence of climatic conditions on the results. The four climatic zones are located in the cities of Athens, Madrid, London and Berlin. The analysed systems are: a) natural gas-fired instantaneous water heaters, b) electric storage water heater, c) solar thermal system with gas- fired instantaneous, d) solar thermal system with electric storage water heater, e) air-source heat pump, f) photovoltaic system with electric storage water heater, and g) photovoltaic system with air-source heat pump. This range of technologies covers the most likely solutions to be implemented across domestic buildings in Europe.The heat pump system (HPWH) with PV considering self-consumption shows the lowest environmen- tal impact in all zones, but is not an attractive investment in the coldest zones due to lower natural gas prices. Thermal solar systems have a high purchase and maintenance costs which do not compensate their energy savings. The PV HPWH system has a greater reduction of emissions and a lower cost than HPWH across a 15-year life. The gas boiler system has the lowest cost in a 15-year period in the coldest areas, despite having a greater environmental impact than the heat pump.(c) 2023 Elsevier B.V. All rights reserved.

Thermoacoustic technology emerges as a sustainable and low-carbon method for energy conversion, leveraging environmentally friendly working mediums and independence from electricity. This study presents the development of a multimode heat-driven thermoacoustic system designed to utilize medium/low-grade heat sources for room-temperature cooling and heating. We constructed both a simulation model and an experimental prototype for a single-unit direct-coupled thermoacoustic system, exploring its performance in heating-only, cooling-only, and hybrid heating and cooling modes. Internal characteristic analysis including an examination of internal exergy loss and a distribution analysis of key parameters was first conducted in the hybrid cooling and heating mode. The results indicated a positive-focused traveling-wave-dominant acoustic field within the thermoacoustic core unit, enhancing energy conversion efficiency. The output system performance was subsequently tested under different working conditions in the heating-only and cooling-only modes. A maximum output heating power of 2.3 kW and a maximum COPh of 1.41 were observed in the heating-only mode. Meanwhile, a cooling power of 748 W and a COPc of 0.4 were obtained in the typical cooling condition at 7 °C when operating in cooling-only mode. These findings underscore the promising potential of thermoacoustic systems for efficiently utilizing medium/low-grade heat sources for cooling and/or heating applications in the future.

Petroleum-based fuels are used extensively as a result of the rising energy demands. Studies on fuels that will replace these fuels are now ongoing. In this study, performance, emission values of 4 different fuels at 4 different torque values were evaluated, and energy and exergy analyses were done utilizing combinations of gasoline, natural gas, and methanol. The tests employed a Lombardini LGW 523 2-cylinder 4-stroke engine. Four different fuels (gasoline, gasoline plus 50 g of natural gas, M20, and M20 plus 50 g of natural gas) were tested at a constant 3000 rpm with four different torque values (5, 10, 15, 20). In tests, it produced the lowest specific fuel consumption and the best emissions when combined with 50 g of natural gas fuel. The purpose of this study was to show that as torque increased, values for fuel, network, exhaust, absorption water, and energy destruction increased, while rates of lost energy decreased and rates of energy destruction increased.

İV ÖZET Bütün dünya'da bir artış gösteren enerji gereksiniminin büyük bir kısmı bir süre daha fosil yakıtlar ve hidrolik enerji ile karşılanabileceği söylenmektedir. Fosil yakıtlar kısa bir süre sonra tükenecek ve bunların yerini yeni enerji kaynaklarının alması gerekecektir. Dünya genelinde son 30-40 yıldır yoğun bir şekilde araştırılmakta olan bu yeni enerji kaynaklarından birisi'de jeotermal enerjidir. Bu çalışmada, Simav'da mevcut jeotermal enerji kaynaklarından yararlanma olanakları araştırılmıştır. Çalışmanın birinci bölümünde mevcut enerji kaynakları ve bu kaynakların içerisinde jeotermal enerji tanıtılarak, jeotermal enerjinin yeri ve önemi anlatılmıştır. İkinci bölümünde, Dünya'da ve Türkiye'de jeotermal enerjinin uygulama alanları hakkında örnekler verilerek ekonomik analizi yapılmıştır. Bu çalışmanın son bölümde ise, Simav ilçesinde bulunan jeotermal kaynaklar, potansiyeli ve uygulamaları hakkında bilgi verildikten sonra çevredeki yerleşim alanlarına da jeotermal enerjinin götürülebilmesi olanakları araştırılmış olup, Muradınlar köyünde yapılmakta olan Fakülte binalarının ısı ihtiyacının fosil yakıtlarla (kömür, fuel- oil) veya jeotermal enerji ile karşılanması düşünülmüş, her ikisininde yatırım ve işletme maliyetleri hesaplanarak, ekonomik ve sosyal faydaları tartışılmıştır. Jeotermal enerji kullanımının yörede etkin bir şekilde yaygınlaşmasıyla ekonomik ve sosyal gelişmenin hızla gerçekleşebileceği sonucuna varılmıştır. ABSTRACT It is estimated that of most of the energy needed in the world will be supplied for a while by focil fuels and hydraulic energy, unfortunately focil fuels will last in a short time. And thus new energy resources will have to fulfill these. In the world one of these new energy resources which have been reseached intersively for the last 30-40 years is geothermal energy. In this study, the utilization of the geothermal energy sources in Simav were researcehed. In the first section of this study the recent energy sources and among these, the importance and place of geothermal energy were explained. In the second section, having given Turkey and in the world economical analysis were made. In the last section of this study, after having been given information about the geothermal sources in Simav, their potential and application, the possibility of taking geothermal energy to neighboring residential areas were researched. Obtaining the heat needed for the building of Technical Education Faculty, which are being built in Muradynlar were considered from focil fuels or geothermal energy investment and running costs of both of then were calculated the social and economical benefits were discussed. It was understood that the intensively usage of geothermal energy in the area will rapidly increase social and economical development of the region. 143

No mundo atual em que vivemos, em constante mudança, o setor dos transportes tem um papel crucial na atividade económica mundial. Contudo, representa um consumo elevado de recursos energéticos e ainda é um dos principais responsáveis pela emissão de gases com efeito de estufa. A mobilidade elétrica e eletrificação das frotas contribuiu para uma redução direta da emissão de gases, representando uma vantagem sobre os veículos com motores de combustão interna. Todavia, a limitação dos sistemas de armazenamento de energia elétrica em termos de autonomia (número de quilómetros percorridos) ainda é um dos maiores entraves a uma maior penetração no mercado dos veículos elétricos. No setor mais específico dos autocarros elétricos, em particular o autocarro de aeroporto, esta desvantagem é amplificada não só pela dimensão e peso, mas também pelos sistemas auxiliares de aquecimento, ventilação e ar-condicionado (AVAC) inerentes a este tipo de veículos. O presente trabalho tem por objetivo a análise e otimização da eficiência energética do modelo e.Cobus, um autocarro de aeroporto. Para alcançar o objetivo foram estudadas algumas unidades e.Cobus em condições reais de operação e analisadas as potências e consumos de energia das diferentes cargas, criando diversos dataset’s. Com os dataset’s elaborados, e recorrendo à plataforma de aprendizagem máquina WEKA, e aplicação de alguns algoritmos, foram desenvolvidos modelos de previsão do consumo de energia que permitiram otimizar a capacidade de armazenamento energético (baterias) destes autocarros, em função da utilização e local geográfico

RESUMEN : La tradicional economía lineal, donde el consumo de productos está dado por tomar, fabricar y desechar, ha traído consigo consecuencias en el medio ambiente y la economía, dada la escasez de recursos finitos, la generación de emisiones al medio ambiente y miles de toneladas de residuos que han saturado la capacidad de gestión. Por ello se requiere migrar hacia una Economía Circular (EC) que logre preservar recursos naturales, extendiendo la vida útil de productos y materiales, aumentando su durabilidad mediante la aplicación de diferentes estrategias con ciclos de remanufactura, reparación, reciclaje y reutilización. En Colombia se han venido desarrollando diferentes iniciativas respecto a la EC siguiendo el modelo europeo, en el que se han intervenido diversos sectores como el de equipos eléctricos y electrónicos, envases y empaques plásticos, baterías, fármacos, llantas y de manera emergente el sector mobiliario, haciendo que dicho sector cobre relevancia, implementando en ellos diferentes estrategias de EC como la de producto como servicio (PSS), la cual consiste en un modelo de negocio donde el consumidor puede acceder a un bien o servicio sin tener que comprarlo, siendo el proveedor del producto-servicio quien se hace cargo de la gestión durante todo su ciclo de vida. En este trabajo se desarrolla una metodología para proponer la configuración a seguir para implementar la estrategia PSS en el sector mobiliario, específicamente mobiliario de Instituciones de Educación superior (IES). Dicha configuración tiene en cuenta factores que incluyen criterios de sostenibilidad, planteando un nuevo modelo de adquisición y gestión de mobiliario, que aporta a la disminución de impactos ambientales y generación de beneficios económicos. Se realiza la validación mediante panel de expertos y caso de estudio en una IES, donde se simula el modelo de gestión de mobiliario basado en PSS mediante dinámica de sistemas, y como resultado se muestran los beneficios, la conveniencia de la aplicación de la estrategia PSS y se incentiva a un cambio de patrones de uso y consumo de productos. ABSTRACT : The traditional linear economy where the consumption of products is given by taking, manufacturing and discarding, has brought environment and the economy consequences, given the scarcity of finite resources, the generation of emissions into the environment and thousands of tons of residues that have saturated the management capacity. For this reason, it is necessary to migrate towards a Circular Economy (CE) that manages to preserve natural resources, extending the useful life of products and materials, increasing their durability through the application of different strategies with cycles of remanufacturing, repair, recycling and reuse. In Colombia, different initiatives have been developed regarding CE following the European model, in which various sectors have been involved, such as electrical and electronic equipment, plastic containers and packaging, batteries, pharmaceuticals, tires and, emergingly, the furniture sector. making this sector relevant, implementing in them different EC strategies such as the product as a service (PSS) which consists of a business model where the consumer can access a good or service without having to buy it, being the supplier of the product-service who is in charge of management throughout its life cycle. In this work, a methodology is developed to propose the configuration to follow to implement the PSS strategy in the furniture sector, specifically furniture of Higher Education Institutions (IES). This configuration takes into account factors that include sustainability criteria, proposing a new furniture acquisition and management model, which contributes to the reduction of environmental impacts and the generation of economic benefits. Validation is carried out through a panel of experts and a case study in a HEI, where the furniture management model based on PSS is simulated through system dynamics, and as a result the benefits and convenience of applying the PSS strategy are shown. and a change in patterns of use and consumption of products is encouraged.

Selective removal of coatings by lasers can facilitate the reuse of coated tools in a circular economy. In order to optimise and control the process, it is essential to study the impact of process input variables on process performance. In this paper, coating removal from tooling was carried out using a picosecond a pulsed fibre laser, in order to investigate the effects of laser pulse energy, pulse frequency, galvo scanning speed and scanning track stepover. A fractional factorial design of experiments and analysis of variance was used to optimise the process; considering cleaning rate, specific energy consumption and surface integrity as assessed by changes in surface roughness and composition of the tooling after laser cleaning. The results shows synergy between cleaning rate and specific energy with the laser pulse frequency and galvo scanning speed as the two most significant factors, while the laser pulse energy had the greatest contribution to changes in surface composition. Based on extensive experiments, the relationship between processing rate and system specific energy consumption was mathematically modelled. The paper contributes a new specific energy model for laser cleaning and provides a benchmark of the process energy requirements compared to other manufacturing processes. Additionally, the generic scientific learning from this is that the rate of energy input is a key tool for maximising cleaning rate and minimising specific energy requirements, while the intensity of energy applied, is a key metric that influences surface integrity. More complex factors, influence the surface integrity.

Engineered cementitious composites (ECCs) are special types of fibre-reinforced cementitious composites (FRCC) with higher strain capacity which can be achieved with low fibre volume as low as 2% and total elimination of coarse aggregates. Due to the outstanding performance of ECCs, they are suitable for various construction and repair applications. However, in order for ECCs to achieve their properties; a high amount of binder which is primarily composed of Portland cement (PC) is used alongside a special type of ultrafine silica sand (USS) which is different from the conventional natural fine aggregates. The production of PC is known to be detrimental to the environment due to its high carbon dioxide emissions coupled with the high consumption of natural resources. Thus, the high use of PC content in ECCs posed a sustainability threat. Similarly, the USS used in ECCs are not readily available everywhere and are expensive. The processing of the USS coupled with its transportation over long distances would also increase the cost and embodied carbon of ECCs. Hence, in order to promote more development and applications of ECCs for various applications; this dissertation aims to provide innovative ways to improve the sustainability of ECCs and their performances. This dissertation offers four solutions to improve the sustainability of ECCs which are (i) use of unconventional industrial by-products as partial replacement of PC (ii) total replacement of PC in ECCs with alternative sustainable binders (iii) replacement of USS in ECCs with recycled materials and (iv) the use of supplementary cementitious materials to replace a high volume of PC. The findings from this study revealed sustainable ECCs with acceptable mechanical and durability performance can be achieved with the use of alternative binders or replacement of the conventional USS used in ECC mixtures. The sustainability and cost assessment of the ECCs indicated that the incorporation of industrial by-products such as blast furnace slag (BFS) especially at higher content is beneficial to reducing the negative environmental impact and economic burden associated with ECCs compared to the conventional ECC. The sustainability index and cost index of the ECCs further showed that the use of BFS is more beneficial when the sustainability and cost of the ECCs are compared with the corresponding performance. Similarly, the use of recycled materials as an alternative to USS was found to result in a significant reduction in the embodied carbon and cost of ECCs. The use of recycled materials such as expanded glass (EG) as aggregates in ECCs was also found to improve the thermal insulation properties of ECCs making such ECC suitable for the production of building envelope elements.

THERMODYNAMIC AND ECONOMIC ANALYSIS OF COMBINED HEAT AND POWER (COGENERATION) STEAM CYCLES SUMMARY Thermodynamic models for twoprocess heating, cogeneration steam cycles were developed in this study. These cycles are an extraction-condensing turbine cycle and a back pressure turbine cycle. Heat and electric outputs were calculated for inlet conditions ranging from 3 MPa, 250 C to 12 MPa, 535 C and process heat supply temperatures ranging from 80 C to 160 C. Furthermore, the performance of these cycles at 0 to 100 percent of their maximum heat outputs were examined. A simple method of economic analysis based on the annual costs was developed. This method can take part load into consideration. An extraction-condensing system and a back pressure system were compared by using this method. Process heating with cogeneration is a thermodinamically effective way of supplying heat and power to the industry. In a central plant, fuel can be burned more efficently, environmental controls can be applied more easily and economies of scale can be used to advantage. Furthermore, producing electricity as a byproduct in such plants is less expensive than producing electricity in power stations. In the extraction-condensing type, steam is expanded to condenser pressure and an extraction is made at the saturation pressure corresponding to the process heat supply temperature. In the back pressure type, steam is expanded only to the saturation pressure correspoding to the process heat supply temperature. The extraction-condensing turbines have the advantage that the electric output can be increased at partial heat loads. On the other hand, back- pressure turbines have a simpler mechanism of load control and lower initial costs. Detailed thermodynamic analysis of these systems appears to be lacking [14]-. For example, information on the variation of heat and electric outputs and thermal efficiencies of different configurations with changes in load and inlet steam conditions is essantial for the initial planning stage. viIn this study, computer modelling and simulation of two steam turbine based cogeneration cycles is made. Nu merical experiments were performed for various steam inlet conditions. Heat and electric outputs of cycles, heat input to the cycles and various parameters based on these thermodynamic quantities were calculated at full load and part load conditions. Partial loads ranging from 0 to 100 percent of full load were considered for the extraction-condensing cycle and partial loads of 37.5 to 100 percent were considered for the back pressure cycle. Thermodynamic Analysis The extraction-condensing turbine cycle consists of steam generator, turbine, condenser, heating condenser, feedwater heaters and pumps. The following assumptions are made regarding this cycle: The condenser is assumed to operate at 10 kPa. Extractions from the turbine to the feedwater heaters, heating condenser and the condenser is assumed to occur with a pressure loss equal to 5 persent of the exraction pressure. Pressure loss in the steam generator is assumed to be 25 percent of the turbine inlet pressure. Enthalpy rise of the feedwater is taken as 70 percent of the theoretically optimum value [13- This value is given by Ahopt = n/n+1 (hab - he) (1) where: n is the number of feedwater heaters, hs*> is the boiler drum satureted liquid enthalpy he is the enthalpy of satureted liquid leaving the condenser The loses in the expansion process through the turbine are accounted for by using an isentropic efficiency, r/, defined as : hi- ho r, = - t- r (2) h>- - hos where : hi is the enthalpy before expansion ho is the enthalpy after expansion hos is the enthalpy after an isentropic expansion This value is taken as 0.8 for the high pressure section of the turbine. The isentropic expansion efficiency for the flow between the heating condenser extraction and the turbine exhaust decreases linearly from 0.8 to 0.5 as the flow to the condenser decreases. Isentropic efficiency or compression in all of the pumps is asumed to be 0.7. viiThe calculations performed in the computer program are summarized in the block diagram of figure 1. Application of the first law of thermodynamics and the conservation of mass to each of the components of the cycle yield the exraction mass flows, work in the turbines and in the pumps, heat transfer in the boiler, heating condenser and in the condenser. Heat output is assumed to be primary output from the cycle. Electric output is considered to be a byproduct. Variation of the heat output is achieved by controlling the flow passing through the condenser. At 100 percent heat output, only the cooling steam flows to the condenser. At no heat output, there is no flow through the heating condenser. Cycle calculations have been performed for 100, 75, 50, 25, and 0 percent of the maximum heat output. Assumptions calculation procedures outlined above for the extraction-condensing cycle also apply for back- pressure cycle. The control of heat output, however, is different. The heat output of the back pressure cycle is varied by changing the mass flow rate through the turbine. Calculations have been performed for 100 to 37.5 percent of the maximum heat output. Properties of water required in the computer programs were computed using the equation and procedures given in [3]- Economic Analysis It is the economic consideration which will determine whether or not a cogeneration plant should be built. A simple method is presented here for determining the economic feasibility of a cogeneration plant. In this method all costs and revenues are expressed on an annual basis for comparison. Two assumption are made. First the heat demand is assumed to be supplied by other means if a cogeneration plant is not built. Therefore only the additional or incremental cost is considered. This includes the turbo generator set, condensers, feedwater heaters, steam generators, additional piping, fuel handling, exhaust cleaning measures, building and consruction costs as well as engineering cost. The second assumption is that all of the byproduct electricity produced can be utilised. A numerical example using this method shows that an extinction condensing cycle should bepreferred if the system is to operate at partial heat loads for long periods of time. Back-pressure cycle will be economically feasible only if the system operates at full load more than 90 percent of the time. However the most economic operation for the extraction-condensing cycle is also realized at full load. vmResults Results of the computer simulation of the two cycles discussed above. The key parameters on which the results are based, are explained below. Heat output per unit mass of steam entering the turbine has a maximum value for a given throttle condition and process heat supply temperature. Heat output from the cycle for a given set of turbine inlet conditions was varied as explained in the thermodinamic a na lysis. It was also found that the thermal efficiency of these cycles, defined as net work output over the heat input. Increasing the process heat supply temperature decreases the electric to heat ratio and the electric out put, increases the heat output. IXEnter the type of the system Turbine inlet pressure and temperature Process heat supply temperature Deter mine feedwater enthalpy rise and Turbine exraetion pressure Determine for the case of no heat output mass flow to the feed water heaters and the condenser r* Select a heat load as a percent of full load L-. Determine mass flows to the feedwater heaters, process heating condenser, condenser, net work, electric output heat output, heat input Figure 1. Block diagram of calculation procedure xi ÖZET Birleşik ısı ve güç çevrimlerinin endüstride kullanımının yaygınlaşması bu konudaki araştırmalara yeni boyutlar kazandırmaktadır. Bu durum göz ününe alınarak endüstride kullanılan buharlı birleşik ısı -güç çevrimleri ne ait termodinamik ve ekonomik çözümlemelerin yapıldığı bu çalışmada beş bölüm bulunmaktadır. Birinci bölümde, yapılan çalışmanın amacı açıklanmış, literatürdeki yerine ve önemine değinilmiştir. Konu ile ilgili kabullerden bahsedilmiştir. ikinci bölümde, buharlı güç çevrimleri hakkında genel bilgi verilmiştir. Çevrimlere ait T-s ve akis diyagramlarının yer aldığı bu bölümde çalışmada dikkate alınan değişkenlerin değişim aralığından bahsedilmiştir. Uçüncü bölümde, termodinamik çözümleme yapılarak, kısmi ve tam yükte ısı ve elektirik enerjisinin değişimi ile proses için gereken ısı enerjisi değeri hesaplanmıştır Dördüncü bölümde yakıt fi ati arı ve yakıt türleri yanısıra isletmelerin ihtiyaç duyduğu güç değerleri ve çalışma süreleri esas alınarak bu çevrimlerin ekonomik analizi yapılmıştır. Son bölümde sonuçların grafiklerle kıyaslama ve tartışması yapılarak her iki çevrime ait değişik değerlerin irdelemesi yapılmıştır. 69