In the United States, 40% of energy use was for electricity generation in 2011, but two thirds of the energy used to produce electricity was lost as heat. Combined heat and power systems are an energy technology that provides electrical and thermal energy at high efficiencies by utilizing excess heat from the process of electricity generation. This technology can offer a decentralized method of energy generation for urban regions which can provide a more reliable, resilient and efficient power supply, and has a lower impact on the environment compared to certain centralized electricity generation systems. In order for the use of combined heat and power systems to become more widespread and mainstream, studies must be performed which analyze their use in various conditions and applications. This work examines the use of a combined heat and power system with a microturbine as the prime mover in residential and commercial scenarios and analyzes the technical and economic feasibility of various system configurations. Energy models are developed for R1, R6 and 2-story office building scenarios using eQUEST, and these results give the electrical and thermal energy requirements for each building. Combined heat and power system models are then developed and presented for each scenario, and the building energy requirements and system component sizes available are considered in order to determine the optimal configurations for each system. The combined heat and power system models designed for each scenario are analyzed to find energy savings, water impacts, and emissions impacts of the system, and each model is examined for economic and environmental feasibility. The models created provide information on the most technically and economically efficient configurations of combined heat and power systems for each scenario examined. Data on system component sizing, system efficiencies, and environmental impacts of each system were determined, as well as how these scenarios compared to the use of traditional centralized energy systems. Combined heat and power has the potential to significantly improve the resiliency, reliability and efficiency of the current energy system in the U.S., and by studying and modeling its uses we more completely understand its function in a range of scenarios and can deploy the systems in a greater number of environments and applications.

The purpose of this thesis is to examine possible waste heat recovery methods in data centers. Predictions indicate that in the next decade data center racks may dissipate 70kW of heat, up from the current levels of 10-15kW. Due to this increase, solutions must be found to increase the efficiency of data center cooling. This thesis will examine possible waste heat recovery technologies which will improve energy efficiency. Possible approaches include phase change materials, thermoelectrics, thermomagnetics, vapor compression cycles, absorbtion and adsorbtion systems. After a thorough evaluation of the possible waste heat engines, the use of an ejector heat pump was evaluated in detail. The principle behind an ejector heat pump is very similar to a vapor compression cycle. However, the compressor is replaced with a pump, boiler and an ejector. These three components require less moving parts and are more cost effective then a comparable compressor, despite a lower efficiency. This system will be examined under general operating conditions in a data center. The heat load is around 15-20kW and air temperatures near 85°C. A parametric study is conducted to determine the viability and cost effectiveness of this system in the data center. Included will be various environmentally friendly working fluids that satisfy the low temperature ranges found in a data center. It is determined that Ammonia presents the best option as a working fluid for this application. Using this system a Coefficient Of Performance of 1.538 at 50°C can be realized. This will result in an estimated 373,000 kW-hr saved over a year and a $36,425 reduction in annual cost. Finally, recommendations for implementation are considered to allow for future design and testing of this viable waste heat recovery device.

This study incorporates the potential use of Variable Frequency Drives on various motors as well as areas of improved heat transfer in an older, mid-sized coal fired power plant. In power plants, fluid flow rates are often controlled using dampers or valves while the motors that power the pumps stay at full speed resulting in a significant amount of wasted electrical power; energy is also lost due to poor heat recovery prior to gases leaving the system. By examining pump usage as well as additional heat available for recovery, potential energy savings will be determined. Preliminary results of five motors suggested for variable frequency drive application show annual savings that total 31.1 GWh, resulting in a 1.66% increase in overall plant efficiency. Total project costs are near $2 million resulting in a simple payback period of less than two years assuming 0.04 $/kWh. For every degree reduction of the flue gas temperature by means of heat recovery that is reused elsewhere in the cycle, 2 Billion BTU of coal would be saved annually. One realistic scenario suggested heat recovery resulting in a 120°F degree reduction of flue gas temperature amounting to a 2.54% increase in cycle efficiency.

Syftet med detta arbete är att sammanställa kunskap om värmeåtervinningssystem för spillvatten i flerbostadshus från litteratur, tidigare studier och relevanta aktörer för ämnesområdet. Syftet är också att göra temperaturmätningar i ett flerbostadshus i Borlänge för att beräkna och analysera energibesparingspotential för Ekoflow värmeväxlaren från Isaksson Rostfria AB. Ekoflow är en spillvattenvärmeväxlare som återvinner värmeenergi ur spillvattnet. Genom spillvattenvärmeväxlare strömmas spillvattnet från avloppet och kallt vattnet i motströmriktningen. Ekoflow har monterats i vissa badhus och hotell och visade bra återvinningsgrader i dessa byggnader. Det är lite svårt att hitta en temperaturmätare på marknaden som kan mäta och lagra mätvärden på en vertikal avloppsstam, därför tillverkades en egen avloppstemperaturmätare som användes för att samla in mätdata för analysering och beräkning av avloppsvärmeförluster. Tillämpningen av tekniken i referensbyggnaden tillför vissa problem. ett problem är att både grå och svartvatten går igenom samma rör vilket minskar temperaturen för spillvattnet. Ett annat problem är att flerbostadshuset inte har någon gemensam anslutningspunkt till den kommunala avloppsledningen, vilket innebär att det kommer att behövas en avloppsvärmeväxlaren för varje stamledning. Energianvändningen i flerbostadshus varierar beroende på boarean och antal boende i huset. Antal boende i referensbyggnaden är inte känt men vattenflödets-och spillvattnets temperaturmätningar visade att byggnaden har hög varmvattenförbrukning. Energibesparingen är beroende av flera parametrar som inkommande kall- och spillvattentemperatur till spillvattenvärmeväxlare samt längden av värmeväxlaren. Energibesparingen för tre olika längder på Ekoflow värmeväxlaren beräknades och en 48 meters värmeväxlare visade energibesparing som ligger på ca. 40 MWh/år vilket motsvarar 24% av varmvattenbehovet i fastigheten. Detta förutsätter att avloppsledningarna kan sammankopplas till en gemensam anslutningspunkt i källarplanet. / The purpose of this work is to compile knowledge of waste water recovery systems in multi-family houses from literature, previous studies and relevant actors on the subject area. The purpose is also to make temperature measurements in a multi-family house in Borlänge to calculate and analyze the energy saving potential of the Ekoflow heat exchanger from Isaksson Rostfria AB. Ekoflow is a waste water heat exchanger that recycles heat energy from wastewater. Through wastewater heat exchanger, the waste water flows from the drain and the cold water in the countercurrent direction. Ekoflow has been installed in some bath houses and hotels and showed good recovery rates in these areas. It is a little difficult to find a temperature meter on the market that can measure and store the measured values of a vertical drainage stream. Therefore, produced own temperature meter, which was used to collect measurement data for analysis and calculation of the results. Application of the technology in the reference building adds some problems. One problem is that both gray and black water pass through the same pipe which reduces the temperature of the waste water. The second problem is that the building does not have a common connection point to the municipal sewers, which means that a heat exchanger will be needed for each main line. Energy consumption in multi-family houses varies depending on the living space and number of residents in the house. The number of residents in the reference building is not known but the temperature and water flow and spill water temperature measurements showed that the building has high hot water consumption. Energy saving depends on several parameters such as incoming cold and waste water temperature to waste water heat exchanger and the length of heat exchanger. The energy savings for three different lengths of the Ekoflow heat exchanger were calculated and a 48-meter heat exchanger showed energy savings of approximately 40 MWh / year, which is profitable from the energy saving perspective.

Submitted by CESAR AUGUSTO AREZO E SILVA JUNIOR null (cesar.arezo@hotmail.com) on 2017-01-10T11:03:30Z No. of bitstreams: 1 Dissertacao_Cesar_Arezo.pdf: 2040140 bytes, checksum: 22ed1c12204c5338583f606a5353e418 (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo a orientação abaixo: O arquivo submetido está sem a ficha catalográfica. A versão submetida por você é considerada a versão final da dissertação/tese, portanto não poderá ocorrer qualquer alteração em seu conteúdo após a aprovação. Corrija esta informação e realize uma nova submissão com o arquivo correto. Agradecemos a compreensão. on 2017-01-13T12:08:52Z (GMT) / Submitted by CESAR AUGUSTO AREZO E SILVA JUNIOR null (cesar.arezo@hotmail.com) on 2017-01-16T17:14:48Z No. of bitstreams: 1 Dissertacao_Cesar_Arezo.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-01-17T15:32:25Z (GMT) No. of bitstreams: 1 silvajunior_caa_me_guara.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) / Made available in DSpace on 2017-01-17T15:32:25Z (GMT). No. of bitstreams: 1 silvajunior_caa_me_guara.pdf: 2053752 bytes, checksum: ac3a36225bdb9c284f25c5d8699786ae (MD5) Previous issue date: 2016-12-16 / As usinas siderúrgicas caracterizam-se, sob o ponto de vista energético, pela grande intensidade de energia empregada em processos de redução do minério de ferro, fusão das matérias-primas e refino do aço líquido obtido. Quanto aos processos utilizados para a produção de aço, destacam-se o emprego de duas rotas tecnológicas: usinas integradas e semi-integradas (mini-mills). As usinas integradas possibilitam a redução do minério de ferro até ferro-gusa e, a partir deste, a obtenção do aço. As mini-mills caracterizam-se pelo emprego de sucatas metálicas, ferro-gusa ou ferro esponja como matérias-primas e pela obtenção, como produtos, de diferentes tipos de aço. Na operação de refino do aço líquido produzido comumente é necessário o emprego de desgaseificadores a vácuo para remoção de contaminantes e, consequentemente, atendimento às especificações do produto acabado. Com isso, as mini-mills demandam potência elétrica para os processos de fusão do aço e vapor superaquecido para obtenção de vácuo nos ejetores do processo de desgaseificação. Para atendimento a legislações ambientais, sistemas de despoeiramento devem ser aplicados às aciarias, disponibilizando grandes vazões de gases quentes provenientes do forno elétrico. A operação do sistema de despoeiramento indica expressivo potencial para recuperação de calor em processos siderúrgicos. Na presente dissertação propõe-se a coleta e análise de dados de operação do sistema de despoeiramento de um forno elétrico a arco de uma mini-mill brasileira, visando concepção e análise técnica-econômica de uma central de cogeração associada à recuperação de calor destes gases do sistema de despoeiramento / The steel industry can be characterized by its high demand of energy in the process of reduction and production of pig iron and steel. For the production of steel the following routes can be highlighted: integrated plants and mini-mills. Integrated plants are used for production steel from iron ore, allowing the reduction of iron ore until pig iron, and pig iron to steel. Mini-mills are used for production of steel through metallic scraps and pig iron. In a mini-mill, the transformation of metallic scraps and pig iron to steel is reached in melting shop areas. The melting shop areas adopt vacuum degassers as a commonly equipment to remove contaminants of liquid steel and consequently reach requirements of finished products. As a consequence, in a melting shop, electricity is applied in electric arc furnaces and overheated steam is applied in vacuum degassers. According to environmental restrictions these melting shops are integrated with dust collectors. The dust collected in electric arc furnaces has great amount of energy and can express a high potential to heat recovering systems. The present dissertation has purpose in collect and analyzes data from an electric arc furnace with a dust collector in a Brazilian mini-mill for developing a thermal-economic analysis of a cogeneration plant integrated in this mini-mill.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / This dissertation presents the experimental result of a system to absorb solar energy to heat up a desalination tower with heat recovery mechanism and a change made in the heated water distribution at the heat storage tank. The system to absorb solar energy consists of solar thermal flat plate collectors for high temperatures and it responsible for the conversion of solar radiation in thermal energy to heat up the water to be desalinated. The change made in the storage tank consists of the installation of a stainless steel pipe with holes equally spaced and arrangement to allow a better distribution of the hot water from the solar collectors in the heat storage tank. The desalination unit has two components: two high temperatures solar collectors and a desalination tower with six stages. In its operation, water is heated in the solar collectors and moves by natural convection to the storage tank, to the bottom of the tower. In the tank, the water transfers heat to the salty water in the first stage of the tower. This heated water transfer heat by evaporation, convection and radiation to the second stage and part of its energy is lost to the ambient. The condensed vapor on the walls of the stages flows down by gravity to be collected in a reservoir installed under the desalination tower. The heat received by the second stage is used to heat up the ater in this stage and the process is repeated in all stages. The performance of the desalination unit was satisfactory. The temperature in the storage tank reached values near 85ÂC and the water temperatures at the outlet of the solar collector were near 100ÂC. The daily production was 31 liters of desalinated water and the GOR-value (gain output ratio) was 1,54

Orientador: Marcelino Pereira do Nascimento / Resumo: Estudos recentes mostram tendência de desenvolvimento de sistemas capazes de recuperar energia dos gases de escape. Apesar de ser de fato uma fonte de energia, os sistemas para recuperação instalados na linha de exaustão mostram grande complexidade e necessidade de muito espaço de instalação. O presente estudo demonstra a viabilidade de recuperação de energia do sistema de arrefecimento com espaço de instalação reduzido. O estudo propõe a geração de vapor através de perfis instalados nas paredes da câmara de combustão e sua aplicação em um ciclo Rankine para gerar trabalho através de expansor. A simulação realizada com o software GT-Power demonstra a possibilidade de extrair calor das câmaras com a mesma eficiência de um sistema convencional de arrefecimento por água e aditivo. Paralelamente, o estudo propõe um sistema de recirculação de gases de exaustão sem o uso de um trocador de calor, patenteado pela empresa patrocinadora, complementando a estratégia para evitar o uso desnecessário de energia em um motor a combustão. Os gases provenientes da linha de baixa pressão da exaustão são admitidos pela linha de ar limpo, em alta pressão, através do uso de uma válvula Laval. Os resultados são provenientes de uma rotina de cálculo em Excel, base VBA. O sistema permite que os gases fluam por fora da turbina e elimina a necessidade de um trocador de calor, resolvendo o maior problema dos sistema convencionais de recirculação de gases em baixa pressão. A combinação das duas soluções,... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Studien syftar till att undersöka teorin bakom kortslutningskåpan, dess potential och begränsningar. Undersökningen inleds med en litteraturstudie vilken följs av en fallstudie där ett system med kortslutningskåpa, med avseende på energibehov och systemkostnad, jämförs med ett system med en vanlig kåpa respektive ett system med värmeåtervinning. Litteraturstudien visar att kortslutningskåpan kan minska nettoluftflödet från köket och på så sätt minska uppvärmningsbehovet. Introduceras för stor mängd kortslutningsluft läcker värme och föroreningar från kåpan till köket. Maximalt kunde 21% av det totala frånluftsflödet kortslutas utan läckage. Fallstudiens energiberäkningar har utförts i programmet BELOK Värmeåtervinning samt i ett av författaren kodat program. De tre systemen testades för två fall med olika drifttid, en lunchrestaurang med låg drifttid och en hamburgerrestaurang med hög drifttid. Kortslutningskåpan minskade energibehovet med 15 % och det återvinnande systemet med dryga 80 %. Trots det minskade energibehovet var det värmeåtervinnande systemet inte ekonomiskt lönsamt i lunchrestaurangen, ty drifttiden var för låg för att de höga investeringskostnaderna skulle hinna betala sig. Kortslutningskåpan betalade sig dock efter 4,2 år. I hamburgerrestaurangen, där drifttiden var högre, betalade sig kortslutningskåpan efter 1,3 år och det återvinnande systemet efter 3,2 år. Över 15 år var dock det återvinnande systemet betydligt mer lönsamt. Jämfört med en vanlig kåpa minskade kortslutningskåpan kostnaderna med 13,3 %. Över samma tidsperiod minskade det värmeåtervinnande systemet kostnaderna med 39,5 %. / This study aims to investigate the theory behind the short circuit hood, its potential and limitations. This is done partly as a literature study and partly as a case study where a system with a short circuit hood, in regards of energy demand and system cost, is compared with a system using an exhaust only hood and with a system using heat recovery. The literature study shows that the short circuit hood can reduce the net air flow from the kitchen and thus decrease the heating demand. If too much air is short circuited, heat and contaminations will leak from the hood to the kitchen. A maximum of 21 % of the total exhaust flow could be short circuited without leakage. The energy calculations in the case study were performed using the program BELOK Värmeåtervinning and in a program coded by the author. The three systems were tested for two cases with different operating hours, a lunch restaurant with few operating hours and a hamburger restaurant with many hours. The energy demand was reduced by 15 % using a short circuit hood and by more than 80 % using the heat recovery system. Despite the reduced energy demand, the heat recovery system was not economically profitable in the lunch restaurant, the operating hours were too low for the big investment costs to pay off. However, the short circuit hood payed off after 4,2 years. In the hamburger restaurant where the operating hours was higher, the short circuit hood payed off after 1,3 years and the heat recovery system after 3,2 years. Over 15 years, however, the heat recovery system was significantly more profitable. Compared to an exhaust only system the short circuit hood reduced the costs by 13,3 %. Over the same period, the heat recovery system reduced the costs by 39,5 %.

The thesis deals with the possibilities of heat recovery in air ventilation systems. After a thorough analysis of the problems, the different ways of ventilation with the return of heat are compared even during simultaneous operation of the heating source. The research includes the selection of a suitable ventilation device with heat recovery based on a first investment and operating costs. Subsequently, the selected ventilation device is used for the HVAC project in the housing part of the multifunctional building. The project is created in BIM Revit software.

The topic of my diploma is a solution of selected aspects of cooling slaughterhouses. The main objective is the solution of mechanical cooling from the technical to the physical expression of nature and theoretical foundations comfort cooling.