Diseño de una vivienda unifamiliar con instalación geotérmica de muy baja entalpía

El objetivo del presente proyecto es el diseño de una vivienda unifamiliar de manera que el aporte de energía no renovable sea el mínimo para conseguir las condiciones de confort óptimas para los ocupantes durante todo el año. Para su diseño se tendrá en cuenta el aporte de energía solar pasiva y el uso de aislantes térmicos a lo largo de la envolvente para la reducción de las necesidades de energía. Se dimensiona una instalación geotérmica para el abastecimiento de calefacción, refrigeración y agua caliente sanitaria (ACS). En este dimensionamiento se incluyen los sondeos geotérmicos, el equipo de bomba de calor y la instalación de suelo radiante. En el estudio de iluminación se analizan las necesidades de alumbrado de la vivienda utilizando luminarias led. Por último se evalúa la viabilidad económica que supone sustituir una instalación de caldera de gasoil por la instalación geotérmica dimensionada y la viabilidad de sustituir luminarias incandescentes por luminarias led. ABSTRACT The purpose of this paper is the design of a single family home with the lowest nonrenewable energy input, so optimum comfort living conditions for the occupants during the whole year can be reached. In order to design the house, both passive solar energy input and the use of thermal insulators will be taken into account. A geothermal installation for the heating, cooling and Domestic Hot Water (DHC) supply will be measured. In this measuring, the boreholls, the heat pump equipment and the radiant floor heating installation are included. In the study of illumination of the house, the lighting needs using LED luminaires are analised. Finally, the economic viability when replacing the installation of a diesel boiler for the measured geothermal installation is assessed, as well as the viability when replacing incandescent luminaires for LED luminaires

Proyecto de mejora de instalaciones de calefacción, ACS y envolvente térmica de un edificio existente

En este escrito se pretende llevar a cabo la realización de un proyecto técnico sobre eficiencia energética en edificios. El proyecto comienza con el estudio de la demanda térmica de un edificio, es decir, de sus necesidades de calefacción, refrigeración y agua caliente sanitaria (ACS). Una vez realizado este análisis, se procede al estudio de distintas alternativas para la disminución del coste asociado al consumo energético del edificio, las cuales son: mejora del aislamiento de la envolvente térmica del edificio, instalación de colectores solares para la producción de ACS y el cambio de los quemadores de las calderas. De estas medidas se han presupuestado aquellas que poseen un bajo periodo de retorno de la inversión, y se ha desarrollado su planificación, programación temporal y análisis económico. ABSTRACT In this document is pretended to be carry out the performance of a technical project about energy efficiency in buildings. The project begins with the study of the thermal demand of the building, that is to say, the heating, cooling and domestic hot water (DHW) needs. Once the analysis has been done, is proceeded the study of different alternatives for diminishing the cost associate to the building energy consumption, which are: improvement of the insulation of the building, solar collector installation to produce DHW and change of the burner of the boilers. Among this measures, has been budgeted the ones that possess a low invest pay-back, and it is been developed their planning, their temporal programming and their economic analysis.

Evaluación de un sistema de energía solar térmica basado en colectores de tubos de vacío para suministro de agua a alta temperatura

Esta tesis pretende contribuir al fomento y utilización de la energía solar como alternativa para la producción de agua caliente en el sector agroindustrial. La demanda de agua caliente es un aspecto clave en un gran número de agroindustrias y explotaciones agrarias. Esta demanda presenta una gran variabilidad, tanto en los horarios en que se solicita como en la temperatura del agua del depósito requerida (TADr), difiriendo del perfil de demanda habitual para uso doméstico. Existe una necesidad de profundizar en la influencia que tiene la variación de la TADr en la eficiencia y viabilidad de estos sistemas. El objetivo principal de esta tesis es caracterizar el funcionamiento de un sistema solar térmico (SST) con captador de tubos de vacío (CTV) para producir agua a temperaturas superiores a las habituales en estos sistemas. Se pretende determinar la influencia que la TADr tiene sobre la eficiencia energética del sistema, cuantificar el volumen de agua caliente que es capaz de suministrar en función de la TADr y determinar la rentabilidad del SST como sistema complementario de suministro. Para ello, se ha diseñado, instalado y puesto a punto un sistema experimental de calentamiento de agua, monitorizando su funcionamiento a diferentes TADr bajo condiciones ambientales reales. Los resultados cuantifican cómo el aumento de la TADr provoca una disminución de la energía suministrada al depósito, pudiendo superar diferencias de 1000 Wh m-2 d-1 entre 40 ºC y 80 ºC, para valores de irradiación solar próximos a 8000 Wh m-2 d-1 (la eficiencia del sistema oscila entre 73% y 56%). Esta reducción es consecuencia de la disminución de la eficiencia del captador y del aumento de las pérdidas de calor en las tuberías del circuito. En cuanto al agua suministrada, cuanto mayor es la TADr, mayor es la irradiación solar requerida para que tenga lugar la primera descarga de agua, aumentando el tiempo entre descargas y disminuyendo el número de éstas a lo largo del día. A medida que se incrementa la TADr, se produce una reducción del volumen de agua suministrado a la TADr, por factores como la pérdida de eficiencia del captador, las pérdidas en las tuberías, la energía acumulada en el agua que no alcanza la TADr y la mayor energía extraída del sistema en el agua producida. Para una TADr de 80 ºC, una parte importante de la energía permanece acumulada en el depósito sin alcanzar la TADr al final del día. Para aprovechar esta energía sería necesario disponer de un sistema complementario de suministro, ya que las pérdidas de calor nocturnas en el depósito pueden reducir considerablemente la energía útil disponible al día siguiente. La utilización del sistema solar como sistema único de suministro es inviable en la mayoría de los casos, especialmente a TADr elevadas, al no ajustarse la demanda de agua caliente a la estacionalidad de la producción del sistema solar, y al existir muchos días sin producción de agua caliente por la ausencia de irradiación mínima. Por el contrario, la inversión del sistema solar como sistema complementario para suministrar parte de la demanda térmica de una instalación es altamente recomendable. La energía útil anual del sistema solar estimada oscila entre 1322 kWh m-2 y 1084 kWh m-2. La mayor rentabilidad se obtendría suponiendo la existencia de una caldera eléctrica, donde la inversión se recuperaría en pocos años -entre 5.7 años a 40 ºC y 7.2 años a 80 ºC -. La rentabilidad también es elevada suponiendo la existencia de una caldera de gasóleo, con periodos de recuperación inferiores a 10 años. En una industria ficticia con demanda de 100 kWh d-1 y caldera de gasóleo existente, la inversión en una instalación solar optimizada sería rentable a cualquier TADr, con valores de VAN cercanos a la inversión realizada -12000 € a 80 ºC y 15000€ a 40 ºC- y un plazo de recuperación de la inversión entre 8 y 10 años. Los resultados de este estudio pueden ser de gran utilidad a la hora de determinar la viabilidad de utilización de sistemas similares para suministrar la demanda de agua caliente de agroindustrias y explotaciones agropecuarias, o para otras aplicaciones en las que se demande agua a temperaturas distintas de la habitual en uso doméstico (60 ºC). En cada caso, los rendimientos y la rentabilidad vendrán determinados por la irradiación de la zona, la temperatura del agua requerida y la curva de demanda de los procesos específicos. ABSTRACT The aim of this thesis is to contribute to the development and use of solar energy as an alternative for producing hot water in the agribusiness sector. Hot water supply is a key issue for a great many agribusinesses and agricultural holdings. Both hot water demand times and required tank water temperature (rTWT) are highly variable, where the demand profile tends to differ from domestic use. Further research is needed on how differences in rTWT influence the performance and feasibility of these systems. The main objective of this thesis is to characterize the performance and test the feasibility of an evacuated tube collector (ETC) solar water heating (SWH) system providing water at a higher temperature than is usual for such systems. The aim is to determine what influence the rTWT has on the system’s energy efficiency, quantify the volume of hot water that the system is capable of supplying at the respective rTWT and establish whether SWH is feasible as a booster supply system for the different analysed rTWTs. To do this, a prototype water heating system has been designed, installed and commissioned and its performance monitored at different rTWTs under real operating conditions. The quantitative results show that a higher rTWT results in a lower energy supply to the tank, where the differences may be greater than 1000 Wh m-2 d-1 from 40 ºC to 80 ºC for insolation values of around 8000 Wh m-2 d-1 (system efficiency ranges from 73% to 56%). The drop in supply is due to lower collector efficiency and greater heat losses from the pipe system. As regards water supplied at the rTWT, the insolation required for the first withdrawal of water to take place is greater at higher rTWTs, where the time between withdrawals increases and the number of withdrawals decreases throughout the day. As rTWT increases, the volume of water supplied at the rTWT decreases due to factors such as lower collector efficiency, pipe system heat losses, energy stored in the water at below the rTWT and more energy being extracted from the system by water heating. For a rTWT of 80 ºC, much of the energy is stored in the tank at below the rTWT at the end of the day. A booster supply system would be required to take advantage of this energy, as overnight tank heat losses may significantly reduce the usable energy available on the following day. It is often not feasible to use the solar system as a single supply system, especially at high rTWTs, as, unlike the supply from the solar heating system which does not produce hot water on many days of the year because insolation is below the required minimum, hot water demand is not seasonal. On the other hand, investment in a solar system as a booster system to meet part of a plant’s heat energy demand is highly recommended. The solar system’s estimated annual usable energy ranges from 1322 kWh m-2 to 1084 kWh m-2. Cost efficiency would be greatest if there were an existing electric boiler, where the payback period would be just a few years —from 5.7 years at 40 ºC to 7.2 years at 80 ºC—. Cost efficiency is also high if there is an existing diesel boiler with payback periods of under 10 years. In a fictitious industry with a demand of 100 kWh day-1 and an existing diesel boiler, the investment in the solar plant would be highly recommended at any rTWT, with a net present value similar to investment costs —12000 € at 80 ºC and 15000 € at 40 ºC— and a payback period of 10 years. The results of this study are potentially very useful for determining the feasibility of using similar systems for meeting the hot water demand of agribusinesses and arable and livestock farms or for other applications demanding water at temperatures not typical of domestic demand (60ºC). Performance and cost efficiency will be determined by the regional insolation, the required water temperature and the demand curve of the specific processes in each case.

Certificación energética mediante la herramienta CE3X y rehabilitación energética de una vivienda unifamiliar

El siguiente proyecto lleva a cabo un estudio sobre la eficiencia energética en una vivienda unifamiliar basándose en la legislación actual europea y española. Para empezar se obtendrá la calificación energética del inmueble mediante el programa informático de la opción simplificada CE3X. A continuación se proporcionará un estudio con las medidas de mejora más adecuadas para mejorar la eficiencia energética de la vivienda, las medidas que se llevarán a cabo serán: la mejora de la envolvente térmica, mejorando el aislamiento de la fachada y la sustitución de ventanas, la instalación de una caldera de biomasa y la instalación de un sistema de colectores solares para cubrir la demanda de calefacción y ACS. Para finalizar se realiza un presupuesto de las medidas de mejoras propuestas, así como un análisis económico y una planificación y programación temporal. ABSTRACT The object of this Project is to carry out a study on the energy efficiency of a single family home in accordance with the present European and Spanish legislation. The first step is to obtain the home energy efficiency by means of a CE3X computer program. The second step is a study with the most appropriate improvement measures is provided in order to improve the home energy efficiency. The measures to be carried out will be as follows: improving the heat insulation, as well as, the facade heat insulation and replacing the windows, installing a biomass heating system and a solar collector in order to satisfy the heating and domestic hot water (DHW) demands. Finally a budget with the proposed improvement measures is made as well as a financial analysis and a time planning and programming of the project.

Investigación sobre la aplicación de energía solar a una depuradora convencional de fangos activos

El consumo de energía es responsable de una parte importante de las emisiones a la atmósfera de CO2, que es uno de los principales causantes del efecto invernadero en nuestro planeta. El aprovechamiento de la energía solar para la producción de agua caliente, permite economizar energía y disminuir el impacto del consumo energético sobre el medio ambiente y por tanto un menor impacto medioambiental. El objetivo de la presente investigación consiste en estudiar el aprovechamiento solar para el calentamiento de los fangos en los digestores anaerobios mediante agua caliente circulando en el interior de un serpentín que rodea la superficie de dicho digestor, como apoyo a los métodos convencionales del calentamiento de fangos como la resistencia eléctrica o el intercambiador de calor mediante la energía obtenida por el gas metano producido en la digestión anaerobia. Para el estudio se utilizaron 3 digestores, dos delos cuales se calentaron con agua caliente en el interior de un serpentín (uno aislado mediante una capa de fibra de vidrio y poliuretano y otro sin aislar).El tercer digestor no tenía calentamiento exterior con el objetivo de observar su comportamiento y comparar su evolución con el resto de los digestores .La comparación de los digestores 1 y 2 nos permitió estudiar la conveniencia de proveer de aislamiento al digestor. La transferencia de calor mediante serpentín de cobre dio valores comprendidos entre 83 y 92%. La aplicación de la instalación a una depuradora a escala real para mantenimiento en el interior del digestor a T=32ºC en diferentes climas: climas templados, cálidos y fríos, consistió en el cálculo de la superficie de colectores solares y superficie de serpentín necesario para cubrir las necesidades energéticas anuales de dicho digestor, así como el estudio de rentabilidad de la instalación, dando los mejores resultados para climas cálidos con períodos de retorno de 12 años y una tasa interna de rentabilidad (TIR) del 16% obteniendo una cobertura anual del 79% de las necesidades energéticas con energía solar térmica. Energy consumption accounts for a significant part of the emissions of CO2, which is one of the main causes of the greenhouse effect on our planet. The use of solar energy for hot water production. can save energy and reduce the impact of energy consumption on the environment and therefore a reduced environmental impact. The objective of this research is to study the solar utilization for heating the sludge in anaerobic digesters by hot water circulating inside a coil surrounding the surface of digester, to support conventional heating methods sludge as the electrical resistance or heat exchanger by energy generated by the methane gas produced in the anaerobic digestion. To study 3 digesters used two models which are heated with hot water within a coil (one insulated by a layer of fiberglass and polyurethane and other uninsulated) .The third digester had no external heating in order to observe their behavior and compare their evolution with the rest of the .The comparison digesters digesters 1 and 2 allowed us to study the advisability of providing insulation to the digester. Heat transfer through copper coil gave values between 83 and 92%. The installation application to a treatment for maintaining full scale within the digester at T = 32ºC in different climates: temperate, warm and cold climates, consisted of calculating the surface area of solar collectors and coil required to cover the annual energy needs of the digester, and the study of profitability of the installation, giving the best results for hot climates with return periods of 12 years and an internal rate of return (IRR) of 16% achieving an annual coverage of 79 % of energy needs with solar energy.

Postharvest characteristics and handling of litchi fruit - an overview

Litchi ( Litchi chinensis Sonn.) is a tropical to subtropical crop that originated in South-East Asia. Litchi fruit are prized on the world market for their flavour, semi-translucent white aril and attractive red skin. Litchi is now grown commercially in many countries and production in Australia, China, Israel, South Africa and Thailand has expanded markedly in recent years. Increased production has made significant contributions to economic development in these countries, especially those in South-East Asia. Non-climacteric litchi fruit are harvested at their visual and organoleptic optimum. They are highly perishable and, consequently, have a short life that limits marketability and potential expansion of demand. Pericarp browning and pathological decay are common and important defects of harvested litchi fruit. Postharvest technologies have been developed to reduce these defects. These technologies involve cooling and heating the fruit, use of various packages and packaging materials and the application of fungicides and other chemicals. Through the use of fungicides and refrigeration, litchi fruit have a storage life of about 30 days. However, when they are removed from storage, their shelf life at ambient temperature is very short due to pericarp browning and fruit rotting. Low temperature acclimation or use of chitsoan as a coating can extend the shelf life. Sulfur dioxide fumigation effectively reduces pericarp browning, but approval from Europe, Australia and Japan for this chemical is likely to be withdrawn due to concerns over sulfur residues in fumigated fruit. Thus, sulfur-free postharvest treatments that maintain fruit skin colour are increasingly important. Alternatives to SO2 fumigation for control of pericarp browning and fruit rotting are pre-storage pathogen management, anoxia treatment, and dipping in 2% hydrogen chloride solution for 6-8 min following storage at 0 degrees C. Insect disinfestation has become increasingly important for the expansion of export markets because of quarantine issues associated with some fruit fly species. Thus, effective disinfestation protocols need to be developed. Heat treatment has shown promise as a quarantine technology, but it injures pericarp tissue and results in skin browning. However, heat treatment can be combined with an acid dip treatment that inhibits browning. Therefore, the primary aim of postharvest litchi research remains the achievement of highly coloured fruit which is free of pests and disease. Future research should focus on disease control before harvest, combined acid and heat treatments after harvest and careful temperature management during storage and transport.

A study in the application of domestic solar assisted heat pumps for heating and cooling

In the present work, the more important parameters of the heat pump system and of solar assisted heat pump systems were analysed in a quantitative way. Ideal and real Rankine cycles applied to the heat pump, with and without subcooling and superheating were studied using practical recommended values for their thermodynamics parameters. Comparative characteristics of refrigerants here analysed looking for their applicability in heat pumps for domestic heating and their effect in the performance of the system. Curves for the variation of the coefficient of performance as a function of condensing and evaporating temperatures were prepared for R12. Air, water and earth as low-grade heat sources and basic heat pump design factors for integrated heat pumps and thermal stores and for solar assisted heat pump-series, parallel and dual-systems were studied. The analysis of the relative performance of these systems demonstrated that the dual system presents advantages in domestic applications. An account of energy requirements for space and hater heating in the domestic sector in the O.K. is presented. The expected primary energy savings by using heat pumps to provide for the heating demand of the domestic sector was found to be of the order of 7%. The availability of solar energy in the U.K. climatic conditions and the characteristics of the solar radiation here studied. Tables and graphical representations in order to calculate the incident solar radiation over a tilted roof were prepared and are given in this study in section IV. In order to analyse and calculate the heating load for the system, new mathematical and graphical relations were developed in section V. A domestic space and water heating system is described and studied. It comprises three main components: a solar radiation absorber, the normal roof of a house, a split heat pump and a thermal store. A mathematical study of the heat exchange characteristics in the roof structure was done. This permits to evaluate the energy collected by the roof acting as a radiation absorber and its efficiency. An indication of the relative contributions from the three low-grade sources: ambient air, solar boost and heat loss from the house to the roof space during operation is given in section VI, together with the average seasonal performance and the energy saving for a prototype system tested at the University of Aston. The seasonal performance as found to be 2.6 and the energy savings by using the system studied 61%. A new store configuration to reduce wasted heat losses is also discussed in section VI.

A heat metering system for energy management on an industrial site

Faced with a future of rising energy costs there is a need for industry to manage energy more carefully in order to meet its economic objectives. A problem besetting the growth of energy conservation in the UK is that a large proportion of energy consumption is used in a low intensive manner in organisations where they would be responsibility for energy efficiency is spread over a large number of personnel who each see only small energy costs. In relation to this problem in the non-energy intensive industrial sector, an application of an energy management technique known as monitoring and targeting (M & T) has been installed at the Whetstone site of the General Electric Company Limited in an attempt to prove it as a means for motivating line management and personnel to save energy. The objective energy saving for which the M & T was devised is very specific. During early energy conservation work at the site there had been a change from continuous to intermittent heating but the maintenance of the strategy was receiving a poor level of commitment from line management and performance was some 5% - 10% less than expected. The M & T is concerned therefore with heat for space heating for which a heat metering system was required. Metering of the site high pressure hot water system posed technical difficulties and expenditure was also limited. This led to a ‘tin-house' design being installed for a price less than the commercial equivalent. The timespan of work to achieve an operational heat metering system was 3 years which meant that energy saving results from the scheme were not observed during the study. If successful the replication potential is the larger non energy intensive sites from which some 30 PT savings could be expected in the UK.

Decision support for lifecycle planning and risk management of small-scale biomass combined heat and power (bCHP) projects in the UK

Biomass is projected to account for approximately half of the new energy production required to achieve the 2020 primary energy target in the UK. Combined heat and power (CHP) bioenergy systems are not only a highly efficient method of energy conversion, at smaller-scales a significant proportion of the heat produced can be effectively utilised for hot water, space heating or industrial heating purposes. However, there are many barriers to project development and this has greatly inhibited deployment in the UK. Project viability is highly subjective to changes in policy, regulation, the finance market and the low cost incumbent; a high carbon centralised energy system. Unidentified or unmitigated barriers occurring during the project lifecycle may not only negatively impact on the project but could ultimately lead to project failure. The research develops a decision support system (DSS) for small-scale (500 kWe to 10 MWe) biomass combustion CHP project development and risk management in the early stages of a potential project’s lifecycle. By supporting developers in the early stages of project development with financial, scheduling and risk management analysis, the research aims to reduce the barriers identified and streamline decision-making. A fuzzy methodology is also applied throughout the developed DSS to support developers in handling the uncertain or approximate information often held at the early stages of the project lifecycle. The DSS is applied to a case study of a recently failed (2011) small-scale biomass CHP project to demonstrate its applicability and benefits. The application highlights that the proposed development within the case study was not viable. Moreover, further analysis of the possible barriers with the DSS confirmed that some possible modifications to be project could have improved this, such as a possible change of feedstock to a waste or residue, addressing the unnecessary land lease cost or by increasing heat utilisation onsite. This analysis is further supported by a practitioner evaluation survey that confirms the research contribution and objectives are achieved.

A barrier and techno-economic analysis of small-scale bCHP (biomass combined heat and power) schemes in the UK

bCHP (Biomass combined heat and power) systems are highly efficient at smaller-scales when a significant proportion of the heat produced can be effectively utilised for hot water, space heating or industrial heating purposes. However, there are many barriers to project development and this has greatly inhibited deployment in the UK. Project viability is highly subjective to changes in policy, regulation, the finance market and the low cost fossil fuel incumbent. The paper reviews the barriers to small-scale bCHP project development in the UK along with a case study of a failed 1.5MWel bCHP scheme. The paper offers possible explanations for the project's failure and suggests adaptations to improve the project resilience. Analysis of the project's: capital structuring contract length and bankability; feedstock type and price uncertainty, and plant oversizing highlight the negative impact of the existing project barriers on project development. The research paper concludes with a discussion on the effects of these barriers on the case study project and this industry more generally. A greater understanding of the techno-economic effects of some barriers for small-scale bCHP schemes is demonstrated within this paper, along with some methods for improving the attractiveness and resilience of projects of this kind. © 2014 Elsevier Ltd.

Integrated assessment of water conservation practices for sustainable management strategies

Miami-Dade County implemented a series of water conservation programs, which included rebate/exchange incentives to encourage the use of high efficiency aerators (AR), showerheads (SH), toilets (HET) and clothes washers (HEW), to respond to the environmental sustainability issue in urban areas. This study first used panel data analysis of water consumption to evaluate the performance and actual water savings of individual programs. Integrated water demand model has also been developed for incorporating property’s physical characteristics into the water consumption profiles. Life cycle assessment (with emphasis on end-use stage in water system) of water intense appliances was conducted to determine the environmental impacts brought by each practice. Approximately 6 to 10 % of water has been saved in the first and second year of implementation of high efficiency appliances, and with continuing savings in the third and fourth years. Water savings (gallons per household per day) for water efficiency appliances were observed at 28 (11.1%) for SH, 34.7 (13.3%) for HET, and 39.7 (14.5%) for HEW. Furthermore, the estimated contributions of high efficiency appliances for reducing water demand in the integrated water demand model were between 5 and 19% (highest in the AR program). Results indicated that adoption of more than one type of water efficiency appliance could significantly reduce residential water demand. For the sustainable water management strategies, the appropriate water conservation rate was projected to be 1 to 2 million gallons per day (MGD) through 2030. With 2 MGD of water savings, the estimated per capita water use (GPCD) could be reduced from approximately 140 to 122 GPCD. Additional efforts are needed to reduce the water demand to US EPA’s “Water Sense” conservation levels of 70 GPCD by 2030. Life cycle assessment results showed that environmental impacts (water and energy demands and greenhouse gas emissions) from end-use and demand phases are most significant within the water system, particularly due to water heating (73% for clothes washer and 93% for showerhead). Estimations of optimal lifespan for appliances (8 to 21 years) implied that earlier replacement with efficiency models is encouraged in order to minimize the environmental impacts brought by current practice.

Design of advanced reverse osmosis and nanofiltration membranes for water purification

Most commercially available reverse osmosis (RO) and nanofiltration (NF) membranes are based on the thin film composite (TFC) aromatic polyamide membranes. However, they have several disadvantages including low resistance to fouling, low chemical and thermal stabilities and limited chlorine tolerance. To address these problems, advanced RO/NF membranes are being developed from polyimides for water and wastewater treatments. The following three projects have resulted from my research. (1) Positively charged and solvent resistant NF membranes. The use of solvent resistant membranes to facilitate small molecule separations has been a long standing industry goal of the chemical and pharmaceutical industries. We developed a solvent resistant membrane by chemically cross-linking of polyimide membrane using polyethylenimine. This membrane showed excellent stability in almost all organic solvents. In addition, this membrane was positively charged due to the amine groups remaining on the surface. As a result, high efficiency (> 95%) and selectivity for multivalent heavy metal removal was achieved. (2) Fouling resistant NF membranes. Antifouling membranes are highly desired for “all” applications because fouling will lead to higher energy demand, increase of cleaning and corresponding down time and reduced life-time of the membrane elements. For fouling prevention, we designed a new membrane system using a coating technique to modify membrane surface properties to avoid adsorption of foulants like humic acid. A layer of water-soluble polymer such as polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyvinyl sulfate (PVS) or sulfonated poly(ether ether ketone) (SPEEK), was adsorbed onto the surface of a positively charged membrane. The resultant membranes have a smooth and almost neutrally charged surface which showed better fouling resistance than both the positively charged NF membranes and commercially available negatively charged NTR-7450 membrane. In addition, these membranes showed high efficiency for removal of multivalent ions (> 95% for both cations and anions). Therefore, these antifouling surfaces can be potentially used for water softening, water desalination and wastewater treatment in a membrane bioreactor (MBR) process. (3) Thermally stable RO membranes. Commercial RO membranes cannot be used at temperature higher than 45°C due to the use of polysulfone substrate, which often limits their applications in industries. We successfully developed polyimides as the membrane substrate for thermally stable RO membranes due to their high thermal resistance. The polyimide-based composite polyamide membranes showed desalination performance comparable to the commercial TFC membrane. However, the key advantage of the polyimide-based membrane is its high thermal stability. As the feed temperature increased from 25oC to 95oC, the water flux increased 5 - 6 times while the salt rejection almost kept constant. This membrane appears to provide a unique solution for hot water desalination and also a feasible way to improve the water productivity by increasing the operating temperature without any drop in salt rejection.

Eficiência Energética, Gestão de Energia e Integração de Renováveis em Instalações Hospitalares

A presente dissertação é o resultado de um estudo realizado entre Março de 2015 e Março de 2016 centrado no tema Eficiência Energética nos Edifícios, no âmbito da Dissertação do 2º ano do Mestrado em Engenharia Eletrotécnica – Sistemas Elétricos de Energia no Instituto Superior de Engenharia do Porto (ISEP). Atualmente, os edifícios são responsáveis por cerca de 40% do consumo de energia na maioria dos países da europa. Energia consumida, principalmente, no aquecimento, arrefecimento e na alimentação de aparelhos elétricos. Os hospitais, como grandes edifícios, são grandes consumidores de energia e, na maioria dos países europeus, situam-se entre os edifícios públicos menos eficientes. Neste contexto, representam um tipo de edifícios cuja atividade apresenta um potencial de poupança energético importante. O tipo de atividade aí desenvolvida, aliada às especificidades do sector da saúde, faz deste tipo de edifícios um alvo de análise e otimização energética bastante apetecível. O presente trabalho passa pelo estudo do potencial para a eficiência energética de um hospital situado na zona do Porto. Foi, inicialmente, efetuado um levantamento das necessidades energéticas, de modo a identificar os sectores prioritários de atuação. Este estudo conta com a análise dos consumos obtidos através do processo de monitorização, substituição da iluminação existente por uma mais eficiente, a instalação de painéis solares para reduzir o consumo destinado às águas quentes sanitárias, a substituição de caldeira a diesel por caldeira a biomassa, substituição de um chiller por um mais eficiente, entre outros. Os consumos registados no hospital em estudo serão comparados com um plano nacional (Eficiência Energética e Hídrica no Sistema Nacional de Saúde), para, desta forma, se perceber quais os consumos do hospital em estudo, quando comparados com outros hospitais.

Avaliação de um chiller de absorção numa unidade de cogeração e trigeração

Portugal é um país dependente da energia do exterior, devido à elevada percentagem de consumo de energia a partir de fontes primárias, como por exemplo o gasóleo. Para colmatar este cenário, têm vindo a criar-se incentivos para o uso de energias renováveis e para intensificação de medidas de eficiência energética, como os sistemas de cogeração, de forma a tornar os processos industriais nacionais mais autónomos e mais competitivos. O presente trabalho, centra-se na avaliação do chiller de absorção na central de trigeração da empresa Monteiro, Ribas-Indústria, SA, com a finalidade de identificar algum problema no funcionamento do chiller. Após efetuado o estudo do chiller, verificou-se que o coeficiente de performance do chiller apresenta valores que variam entre 0,75 e 0,81, que comparado com o valor especificado, não apresenta grande diferença. No que toca à potência do chiller, esta apresentou valores entre 948 e 1045 kW. Estes valores estavam bem abaixo da potência especificada pelos fornecedores. Assim, pretendeu-se propor medidas para melhor a potência obtida. Para o efeito foi sugerido o aquecimento da corrente que atua como fonte de calor para o chiller, a corrente de água quente. Embora a empresa apresente a solução para o problema, um permutador de vapor para o aquecimento da corrente de água quente, este não se encontra em funcionamento contínuo, levando a uma potência mais baixa.

Techno-economic analysis of three HVAC retrofitting options

Accounting for around 40% of the total final energy consumption, the building stock is an important area of focus on the way to reaching the energy goals set for the European Union. The relatively small share of new buildings makes renovation of existing buildings possibly the most feasible way of improving the overall energy performance of the building stock. This of course involves improvements on the climate shell, for example by additional insulation or change of window glazing, but also installation of new heating systems, to increase the energy efficiency and to fit the new heat load after renovation. In the choice of systems for heating, ventilation and air conditioning (HVAC), it is important to consider their performance for space heating as well as for domestic hot water (DHW), especially for a renovated house where the DHW share of the total heating consumption is larger. The present study treats the retrofitting of a generic single family house, which was defined as a reference building in a European energy renovation project. Three HVAC retrofitting options were compared from a techno-economic point of view: A) Air-to-water heat pump (AWHP) and mechanical ventilation with heat recovery (MVHR), B) Exhaust air heat pump (EAHP) with low-temperature ventilation radiators, and C) Gas boiler and ventilation with MVHR. The systems were simulated for houses with two levels of heating demand and four different locations: Stockholm, Gdansk, Stuttgart and London. They were then evaluated by means of life cycle cost (LCC) and primary energy consumption. Dynamic simulations were done in TRNSYS 17. In most cases, system C with gas boiler and MVHR was found to be the cheapest retrofitting option from a life cycle perspective. The advantage over the heat pump systems was particularly clear for a house in Germany, due to the large discrepancy between national prices of natural gas and electricity. In Sweden, where the price difference is much smaller, the heat pump systems had almost as low or even lower life cycle costs than the gas boiler system. Considering the limited availability of natural gas in Sweden, systems A and B would be the better options. From a primary energy point of view system A was the best option throughout, while system B often had the highest primary energy consumption. The limited capacity of the EAHP forced it to use more auxiliary heating than the other systems did, which lowered its COP. The AWHP managed the DHW load better due to a higher capacity, but had a lower COP than the EAHP in space heating mode. Systems A and C were notably favoured by the air heat recovery, which significantly reduced the heating demand. It was also seen that the DHW share of the total heating consumption was, as expected, larger for the house with the lower space heating demand. This confirms the supposition that it is important to include DHW in the study of HVAC systems for retrofitting.