Mejoramiento del comportamiento térmico de sistemas de calentamiento de agua solares termosifónicos hechos con materiales no convencionales y con tanques de almacenamiento verticales y horizontales Performance improvement of solar thermosyphonic systems for water heating made of non conventional materials and using horizontal and vertical storage tanks

El objeto de estudio de este proyecto son los sistemas de calentamiento de agua mediante energía solar que funcionan termosifónicamente. En particular se tratará con dos diseños particulares generados por fabricantes de la Provincia de Córdoba y que han solicitado el asesoramiento del Grupo de Energía Solar (GES) para el mejoramiento de la performance térmica de dichos equipos. Se trata de dos sistemas que tienen materiales no tradicionales y se diferencian además por tener una distinta disposición del tanque de almacenamiento: uno es en forma vertical y el otro en forma horizontal. Basados en los resultados de un ensayo bajo norma internacional, donde se detectaron algunas puntos factibles de mejora, se propone en este proyecto el análisis en detalle de los equipos, para lo cual se les debe desarmar completos, para realizar un estudio analítico y experimental de los mismos con el objeto de hacer un planteo teórico-analítico del comportamiento de los mismos, con la implementación de propuestas de mejora y chequeo de los resultados. Se propone entonces como objetivo lograr un mejoramiento de la performance térmica de los citados equipos a partir de un estudio experimental y analítico. Asumiendo esta posibilidad de mejora, se plantea la hipótesis de que es posible representar el funcionamiento de estos equipos mediante modelos físico-matemáticos desarrollados a partir de ecuaciones y correlaciones conocidas y procesos a interpretar mediante resoluciones numéricas y softwares específicos de simulación. De esta manera, se plantea el despieze completo de los equipos para estudiar en detalle su estructura y conexiones internas y a partir de la geometría, dimensiones y propiedades termofísicas de materiales constructivos y fluidos de trabajo, realizar modelos físico-matemáticos que permitan realizar variaciones de propiedades y geometría y así buscar las mejores combinaciones que produzcan equipos más eficientes térmicamente. Los modelos físico-matemáticos serán codificados en lenguajes de alto nivel para poder luego de una validación de los modelos, correr simulaciones en un software de reconocimiento internacional que permite sumar dichos modelos mediante un protocolo de comunicación, haciendo que las poderosas prestaciones del software se puedan aplicar a nuestros modelos. Se complementará el estudio con un análisis exergético para identificar los puntos críticos en que se producen las pérdidas de oportunidad de aprovechar la energía disponible, para así analizar cómo solucionar los problemas en dichos puntos. Los materiales a utilizar serán los propios equipos provistos por los fabricantes, que serán modificados convenientemente para operarlos como prototipos Se espera obtener un conocimiento acabado de los procesos y principios de funcionamiento de los equipos, que permita plantear las mejoras, las cuales se implementarán en los prototipos, realizándose una medición mediante norma igual a la inicial para ver en que magnitud se logran las mejoras esperadas. Se pretende además que las mejoras a implementar, en la etapa de transferencia a las empresas involucradas, redunden no sólo en un beneficio técnico, sino que también los sea desde el punto de vista económico. Para ello se trabajará también sobre los procesos y métodos de fabricación para que los equipos mejorados no sean mas caros que los originales y de ser posible sean aún más económicos, todo esto apuntando a la difusión de la energía solar térmica y poner al alcance de todos estos equipos tan convenientes para la propagación de las energías limpias. El proyecto redundará también en un importante beneficio para el conocimiento de la comunidad científica en general, con el aporte de nuevos resultados en diseños novedosos y con nuevos materiales. Además, la institución se beneficiará con la formación que obtendrán los integrantes del proyecto, muchos de ellos en etapa de realización de sus estudios de posgrado y en una etapa importante de su vida como investigadores. The main goal of this project is the improvement of two thermosyphonic solar water heating systems, made of non conventional materials and with different arrangement of their storage tanks: one is vertical and the other one horizontal. The thermosyphonic systems are provided by manufacturers of the Córdoba Province, who came to the Solar Energy Group (GES) of the National University of Río Cuarto looking for help for the design of their products. In an agreement with these manufacturers, it was proposed this project in order to work analytically and experimentally in order to obtain physical-mathematical models of these two systems, which allow for changes to look by means of simulations the best changes to implement on the equipments for the improvement of their thermal performance. Then, the materials to be used are the proper systems provided by the manufacturers, which will be disarmed to be studied in detail. After the analytical study the proposals of improvement will be implemented in a high level language of programming to perform simulations in the environment of a well-known software for energy simulations (TRNSYS). After the simulations, the best modifications will be physically implemented in the prototypes to perform finally the same normalized test of the beginning and check the magnitude of the implemented improvements. The importance of this project is based on the offer of better systems the companies would make, which would benefit the deployment of the thermal solar energy. Another relevant point is to make the new equipments at the same cost of the previous ones or cheaper, in order to achieve a good deployment of the solar water heating systems; then, the manufacture processes and methods must be studied to obtain not only good technical solutions, but also economical equipments. In addition, this project will contribute to the increasing of the knowledge in the area of thermosyphonic solar systems and the training of postgraduate students.

Water Heating, 2011

Although there are many ways to cut you water heating bills, the all fall into two broad categories: reducing the amount of hot water you use and making your water heating system more efficient. Fortunately, there are several strategies that can help you consume less energy and save money - and still meet you hot water needs without sacrificing comfort or practicality. The booklet was designed to answer common questions about hot water systems and to provide you with the information necessary to make informed decision about a wide variety of topics, ranging from repairing hot water faucet leaks an insulation water supply pipes to installing low-flow shower heads and tuning you your existing water heather. You'll also find details on what to consider when it's time to go comparison shopping for a new water heater-including an evaluation of the alternatives to the common gas or electric storage tank unit that's found in the majority of homes in Iowa and across the country.

Brazilian solar water heating systems evaluation

The Brazilian National Electricity Conservation Program - PROCEL - runs regular surveys in the electric-energy-consumption market. These studies are used as valuable data to better plan the actions of this program. These data also evaluate the program's performance by identifying the level of penetration of the most efficient electric equipment within the residential sector. PROCEL's main lines of action is to promote and make available the most efficient technologies. Based on the results from the latest survey, it is estimated that 24% of the electric-energy consumption of the residential sector is used by electric shower devices, which instantaneously heat the water that flows through them, normally using an electric resistance of 5 kW. These are an important factor in a country where electric-heating devices are present in about 73% of Brazilian households. Keeping that in mind, the purpose of this work is to present the main results of the Brazilian Solar-Water-Heating-Systems Evaluation, finished in 2010, where 535 installations were visited and more than 50 researchers from different universities participated in the project. Moreover, seven Brazilian cities were selected to be studied. The information was collected from field research and statistically treated. The collected information focused on the adequacy of the project to the household, installation, operation and life cycle of the systems, as well as the users' satisfaction level. Technical questionnaires were developed to summarize all the required information, such as a Web site designed to organize and manage the data collected and a Matlab application that performed the dimensioning and F-chart systems evaluation. Quality indicators were created through a full system monitoring, with thermographic analysis and evaluation of shading influence at the system's efficiency, using the Ecotect software.

Water heating; a reference book on the application of gas for water heating, with special reference to large volume water uses.

Mode of access: Internet.

A study of performance characteristics of domestic water heating equipment, conducted for the Federal Housing Administration under contract no. HA-fh-646 (amendment no. 1) May 10, 1956 /

Mode of access: Internet.

High temperature water heating systems.

"December 1991."

Kaukolämpöverkon paluuveden hyödyntäminen lämmityksessä

Tässä diplomityössä on määritetty paluuvesilämmityksen mahdollisuudet Savon Voima Oyj:n kaukolämpöpaikkakunnilla. Työssä tarkasteltiin paluuvesilämmityksen tuoman paremman kaukolämpöveden jäähtymän vaikutuksia kaukolämpöverkkoon ja energiantuotantoon sekä laskettiin esimerkkipaikkakunnilla kaukolämmön paluuveden lämpötilan alentumisen tuomat rahalliset hyödyt. Lisäksi tarkasteltiin paluuvesilämmityksen taloudellisuutta esimerkkipaikkakunnilla. Laskennassa saatiin paluuvesilämmityksen tuomaksi jäähtymähyödyksi pumppauskustannuksissa 0,7 – 0,8 €/MWh ja lämpöhäviöissä 1,5 – 2,9 €/MWh. Iisalmessa sähköntuotannon lisääntymisestä saadaan hyötyä 0,7 €/MWh. Suurin hyöty saadaan Pielaveden ja Suonenjoen biolämpökeskusten lämmöntalteenotolla varustetuista savukaasupesureista. Pielavedellä tämä hyöty on 6,4 €/MWh ja Suonenjoella 6,1 €/MWh. Paluuvesilämmityksen kannattavuus asuinkiinteistöissä vaatii lämmöntuotannon yhteydessä olevan savukaasupesurin tuoman rahallisen hyödyn. Esimerkiksi Iisalmessa asiakkaalle myönnettävissä oleva jäähtymähyvitys paluuvesilämmöstä ei riitä kattamaan paluuvesilämmityksen suurempia investointikuluja. Myös pesuripaikkakunnilla kannattavuus vaatii suuren vuosittaisen lämmönkäytön. Tavoiteltaessa 8 vuoden korollista takaisinmaksuaikaa vaatii kannattavuus kohteelta Pielavedellä 250 MWh:n ja Suonejoella 300 MWh:n vuosittaisen lämmönkäytön. Myös asiakkaan sijainnin sopivuus kaukolämpöverkossa paluuvesilämmitykseen täytyy tarkastella tapauskohtaisesti. Paluuvesilämmitys ei tule työn tulosten perusteella tulevaisuudessa yleisesti käyttöön, mutta yksittäisiä asiakkaita siihen voidaan liittää.

Solar energy use for water pre-heating in boilers of agro-industries

Energy consumption in the world has been growing every year. The industrial sector represents 27.32% of the world energy demand. Heating systems that use solar energy may contribute with a percentage of the total energy required by industries. This work aimed to study the use of vacuum solar collectors for water pre-heating in boilers. We used four collectors installed according to NBR 15,569; water flow through the tubes was 0.058 L/s, and temperature in the inlet and outlet pipes was measured. Results showed that instantaneous radiation, and inlet fluid and room temperatures are variables that influence the process, reaching water maximum temperature in the solar collector outlet of 97.9 °C, and efficiency of approximately 65% for most experiments. For the financial viability evaluation, the payback study was applied, which resulted in 4; 7 and 5 years, for the respective sources: firewood, LPG (liquefied petroleum gas), and electricity. Regarding the calculation of the annual contribution to the reduction of greenhouse gases, it was, respectively, 2.162 and 356 kg of CO2 per m² of collector tubes, in comparison with firewood and LPG.

Computer tools applied to analysis of solar water heaters

The simulation programs are important tools to analyze the different energetic alternatives, including the use of renewable energy. The objective of this study was to analyze comparatively the different computer tools available for modeling of solar water heaters. Among the main simulation software of solar thermal systems, there are: RETScreen International, EnergyPlus, TRNSYS, SolDesigner, SolarPro, e T*SOL. Among the tools mentioned, only EnergyPlus and RETScreen International are free, but they allow obtaining interesting results when applied together. The first one has a detailed module of energy analysis of solar water heaters, while the second one provides an detailed economic feasibility study and an assessment of emissions of greenhouse gases. RETScreen International and EnergyPlus programs are aimed at a diverse audience, including designers, researchers and energy planners.

Análise da viabilidade econômica de um sistema de aquecimento solar de água para uma empresa do setor hoteleiro

This paper presents an analysis of technical and financial feasibility of the use of a solar system for water heating in a fictitious hotel located in the Northeast region. Thereunto it is used techniques of solar collectors´ sizing and methods of financial mathematics, such as Net Present Value (NPV), Internal Rate of Return (IRR) and Payback. It will also be presented a sensitivity analysis to verify which are the factors that impact the viability of the solar heating. Comparative analysis will be used concerning three cities of distinct regions of Brazil: Curitiba, Belém and João Pessoa. The viability of using a solar heating system will be demonstrated to the whole Brazil, especially to the northeast region as it is the most viable for such an application of solar power because of its high levels of solar radiation. Among the cities examined for a future installation of solar heating systems for water heating in the hotel chain, João Pessoa was the one that has proved more viable.

A popular treatise on the warming and ventilation of buildings; showing the advantages of the improved system of heated water circulation, &c. ...

Mode of access: Internet.

A practical treatise on warming buildings by hot water; on ventilation, and the various methods of distributing artificial heat, and their effects on animal and vegetable physiology. To which are added, an inquiry into the laws of radiant and conducted heat, the chemical constitution of coal, and the combustion of smoke.

"In the present work there have been incorporated several papers ... which have been read before the Institution of Civil Engineers; and also the author's articles on 'Stoves' and 'Ventilation,' published in the Encyclopædia metropolitana."--Pref.

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.

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.

Análise da viabilidade da utilização de colectores solares

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecância