<p>One of the great challenges facing society is to convert theglobal energy system to a sustainable process. Currently, 80%of the world´s energy is supplied through the combustionof fossil fuels. Not only are the fossil resources limited, theutilisation also increases the level of greenhouse gases in theatmosphere. The convertion to a sustainable energy system isproblematic since the technology needed to exploit mostnon-fossil energy sources is not yet fully developed, e.g.solar energy. Biofuel is an available renewable energy sourcewhich is already widely used in many countries. If an effectiveswitch-over from fossil fuels to biofuels is to be realised,biofuels must be viewed as a limited resource. Consequently, itis important that the handling, upgrading and utilisationprocesses involving biofuels are efficient so that itspotential can be fully exploited.</p><p>This thesis considers efficient biofuel utilisation andupgrading within the sawmill industry. The goal has been toanalyse not only the technical opportunities for energy savingsin the sawmill industry, but also to analyse the costeffectiveness and environmental impact of studied measures. Theheat demand of the sawmill industry is almost completelycovered by its own by-products; primarily bark, sawdust andwood chips. The increased demand and improved economic value ofwoody biofuels on the market is thus an incentive for thesawmill industry to place more focus on energy issues. Thesawmill industry also has a more or less constant heat loadover the year, which is a beneficial factor for integrationwith district heating networks, biofuel upgrading plants andcombined heat and power plants.</p><p>The conclusion of the study is that a variety of energyproducts such as heat, unrefined biofuel, pellets andelectricity can be efficiently produced in the sawmill industryand sold for profit to external customers. The payback periodsfor the proposed investments are moderate and both theemissions of volatile organic compounds and global CO2 aredecreased. Should the proposed measures be fully implemented atSwedish sawmills, about 2.8 TWh of biofuel could be savedannually, 0.5 TWh of waste heat could be sold as districtheating and 0.8 TWh of green electricity could be produced.Language: English</p><p><b>Keywords:</b>Sawmill industry, energy efficiency, heatrecovery, integration, biofuel, upgrading, district heating,fuel pellets, CHP, VOC, CO2</p>

Idag ställs stora krav på företag att vara miljömedvetna och resurseffektiva i sin verksamhet. Vid mjukpapperstillverkning används stora energimängder och inom industrin har det under många år funnits en strävan att energieffektivisera processer och att tillvarata spillenergi, bland annat genom värmeåtervinning. Valmet Tissue Technology Center i Karlstad har idag en pilotmaskinen utan värmeåtervinningssystem. Den här undersökningen gjordes i syfte att ta reda på hur stor återvinningspotentialen är för värmeväxling i pilotmaskinens torkpartier, bestående av Yankeekåpan och TAD-cylindrarna. Tre maskinkoncept undersöktes: DCT®, NTT™ och TAD. Entalpi och effekt i utgående torkluft bestämdes utifrån dess massflöde, temperatur och fukthalt för respektive koncept och torkparti. För att beräkna återvinningspotential i luftflödena undersöktes effektbehov för avsättningsalternativ bestående av förvärmning av förbränningsluft och make-up air, uppvärmning av radiatorvatten samt ånggenerering med Waste Heat Steam Generator. Effekt- och energimässig återvinningspotential beräknades dels teoretiskt och dels reellt med simuleringsprogram för befintliga produkter. Ekonomisk besparing från minskad energianvändning samt investeringskostnad för respektive avsättningsalternativ och torkparti beräknades. Paybacktid användes som mått på ekonomisk lönsamhet. Utöver ovanstående undersöktes om det finns ett samband mellan aktivitet på pilotmaskinen och effekttopparna för fjärrvärmeanvändning i den aktuella byggnaden. Störst entalpi har utgående torkluftsflöden från Yankeekåpan vid DCT-körning följt av NTT-körning. Den största effektmässiga återvinningspotentialen för luftförvärmning finns i TAD-cylinder 1 men betydande tryckfall uppstår i värmeväxlaren på grund av stora luftflöden. Waste Heat Steam Generator kan inte användas ihop med pilotmaskinen på grund av för låg entalpi och effekt i utgående torkluft. Generellt är den reella återvinningspotentialen vid luftförvärmning mindre än den teoretiskt beräknade. Totalt innebär värmeväxling från Yankeekåpan den största årliga energibesparingen vid luftförvärmning. Reell energibesparing vid luftförvärmning i Yankeekåpan är 55 MWh per år vilket motsvarar 4 300 kg gasol. För uppvärmning av radiatorvatten finns den största effekt- och energimässiga återvinningspotentialen vid värmeväxling i Yankeekåpan under DCT-körning följt av NTT-körning. TAD-körning innebär en mindre återvinningspotential vid värmeväxling både i Yankeekåpan och TAD-cylindrarna. Totalt innebär värmeväxling från Yankeekåpan den största årliga energibesparingen vid uppvärmning av radiatorvatten. Reell energibesparing vid uppvärmning av radiatorvatten med torkluft från Yankeekåpan är 153 MWh fjärrvärme per år. Årlig kostnadsbesparing vid luftförvärmning är 43 000 SEK och vid uppvärmning av radiatorvatten 63 400 SEK. Paybacktid för investering i luftförvärmning är 2,6 år och för uppvärmning av radiatorvatten 4,4 år. Ett samband mellan att pilotmaskinen körs och hög fjärrvärmeförbrukning finns, dock är det rutinförändringar kring lokalventilering under körning som främst kan bidra till att sänka de högsta effekttopparna. / There are great demands on industrial companies today to be environmentally responsible and resource-efficient. Within the paper and tissue industry a lot of energy is being used in the processes and since many years there’s been a development towards a more efficient energy use, for example by recovery of waste heat. Valmet Tissue Technology Center in Karlstad, Sweden, has a pilot tissue machine without a waste heat recovery system. This thesis was carried out to investigate the waste heat recovery potential of the pilot machine’s drying sections, being the Yankee hood and TAD cylinders. Three different concepts of the machine were studied: DCT®, NTT™ and TAD. The enthalpy and heat flows of the exhaust air from the drying sections were calculated by the air’s mass flow, temperature and humidity. To calculate the heat recovery potential the heat demand for pre-heating combustion and make-up air, heating radiator water and generating steam by using a Waste Heat Steam Generator was investigated. The heat recovery potential was calculated theoretically but also simulated using programs for real heat exchangers. Economic savings from reduced energy use and investment costs was used to calculate the payback time for each investment alternative. As a separate task the maximum district heating loads in the facility of the pilot machine was cross checked with the pilot machine activity, to clarify any relationship between them. The largest enthalpy was found to be in the exhaust air from the Yankee hood when running the DCT concept followed by the NTT concept. However, the largest heat flow is in the exhaust air from the first TAD cylinder. The air from the first TAD cylinder meant the largest heat recovery potential but caused big pressure drops in the heat exchanger. The Waste Heat Steam Generator cannot be used together with the pilot machine due to too low enthalpy and heat flow in the exhaust air from the drying sections. In general the real heat recovery potential when pre-heating combustion and make-up air is smaller than the theoretical potential. In total, heat exchange using exhaust air from the Yankee hood means the largest energy saving when pre-heating air. The real energy saving when pre-heating air using outgoing air from the Yankee hood is 55 MWh per year, meaning 4 300 kg of propane. The largest potential for heating radiator water occurs when using exhaust air from the Yankee hood when running the DCT concept followed by the NTT concept. The TAD concept means smaller heat recovery potential regardless of air from the Yankee hood or TAD cylinders is being used. In total, heat exchange using outgoing air from the Yankee hood means the largest yearly energy saving when heating radiator water, the real energy saving in district heating being 153 MWh per year. The economic saving when pre-heating air is 43 000 SEK per year and when heating radiator water 63 400 SEK per year. The payback time when investing in pre-heating air is 2,6 years and when heating radiator water 4,4 years. A relationship between running the pilot machine and big loads of district heating use can be seen. However, changing the routines of ventilation in the machine hall during trial days would probably be the easiest way to reduce the maximum loads.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-05-21T13:43:20Z No. of bitstreams: 1 Dário da Rosa Cruz.pdf: 2357249 bytes, checksum: cc31613a7629955b25090b2c81265ab5 (MD5) / Made available in DSpace on 2015-05-21T13:43:20Z (GMT). No. of bitstreams: 1 Dário da Rosa Cruz.pdf: 2357249 bytes, checksum: cc31613a7629955b25090b2c81265ab5 (MD5) Previous issue date: 2015-01-09 / IFSUL - Instituto Federal de Educação, Ciência e Tecnologia Sul-rio-grandense / No presente trabalho foi analisado um sistema de cogeração de uma empresa de alimentos que utiliza, em seu processo produtivo, diversas utilidades. Estes processos geram resíduos industriais, como sólidos, líquidos e também resíduos térmicos. Atualmente muito tem se falado sobre eficiência energética no setor de utilidades, a qual impacta diretamente nos custos operacionais de produção. O objetivo deste trabalho é identificar potenciais térmicos disponíveis para a simulação de um sistema de trigeração, que utiliza sistema de refrigeração por absorção amônia/água como uma alternativa na redução dos custos operacionais mediante a produção de água gelada e de refrigeração para túneis de congelamento. Na empresa em análise, a demanda por energia elétrica para sistemas de refrigeração por compressão representa atualmente 60% da energia elétrica total da fábrica. Deste modo, sistemas de refrigeração por absorção mostram-se interessantes para diversas aplicações, pois são movidos por energia térmica ao invés de energia elétrica. Neste estudo são analisadas as influências da temperatura de condensação, temperatura de evaporação, temperatura do gerador e concentrações de amônia sobre o COP do sistema de refrigeração por absorção amônia/água. Para a análise destas influências, foi realizado o modelamento matemático e desenvolvido um programa no EES (Engineering Equation Solver) e os resultados da simulação foram comparados com os resultados encontrados nas simulações do Handbook fundamentals da ASHRAE (2009). A partir daí são simulados três diferentes casos para os sistemas de absorção em estudo, onde os dados coletados na empresa, referentes aos potenciais de recuperação de calor, e os parâmetros da ASHRAE para sistemas de refrigeração por absorção NH3/H2O, são simulados e analisados mediante o programa IPSEpro®. Uma análise econômica é realizada, onde se pode concluir quanto à melhor configuração do sistema de trigeração sugerido. O percentual de economia, referente à energia elétrica consumida pelos compressores de refrigeração adotados foi de 8,7%, o qual proporcionará uma economia líquida mensal de R$ 135.391,41. O custo de energia elétrica considerado foi de R$ 0,1968/kWh e a TMA (taxa mínima de atratividade) considerada no projeto foi de 15,7%. A melhor situação apresentada foi a do caso 3, onde o valor do capital investido foi de R$ 5.368.700,00 referente à aquisição dos equipamentos e instalação e a TIR (taxa interna de retorno) ficou em 15,7%, o VPL (valor presente líquido) para 10 anos ficou em R$ 2.443.000,00 e o tempo de retorno payback se dará em 6,07 anos ou 73 meses. / In this present study, a cogeneration system is analyzed in a food company that uses several utilities in its productive process. These processes generate industrial residues, such as solids, liquids and also thermal residues. Currently, much has been said about energy efficiency in the utilities department to which directly impact the operational costs of production. The goal of this study is to identify thermal and energy potentials available for the simulation of a trigeneration system that uses absorption ammonia/water cooling system as an alternative to reduce operational costs through the production of cold water and the cooling of freezing tunnels. In the analyzed company, the demand for electric energy for the cooling systems by compression, represents lately 60% of all the electric energy of the factory. This way, cooling systems by absorption become interesting for many different applications, since they are activated by thermal energy instead of electric energy. In this study the influences of the condensation temperature, evaporation temperature, generator temperature and ammonia concentration by COP of absorption ammonia/water cooling systems are analyzed. For the fulfillment of these analysis, the mathematical modeling is carried out and an EES program is developed and compared through simulations performed in Handbook fundamentals by ASHRAE (2009). Therefore, three cases different are simulated for the absorption systems in study, where the data presented for the company potential recovery of heat a boiler and the ASHRAE guidelines for an ammonia/water absorption refrigeration systems, are simulated and analyzed through the IPSEpro software. An economical analysis is performed where it is possible to conclude the best configuration of the trigeneration system suggested. The percentage of economy concerned to the electric energy consumed by the adopted cooling compressors was 8.7%. It will proportionate a mouthy economy of around R$ 135,391.41. The costs of electric energy considered was R$ 0.1968/kWh and the TMA (minimal tax of attractiveness) considered in the project was 15.7% the best situation presented was the case 3, where the value of invested capital was R$ 5,368,700.00 concerned to the acquisition and installation of equipments. The TIR (internal rate of return) was in 15.7%, the VPL (net present value) for ten years was R$ 2,443,000.00 and the payback will occur in 6.07 years or 73 months.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Extensive research and development activities have been conducted to explore opportunities for sustainable and viable methods of producing potable water using solar energy. This project included a new configuration for the solar cooker with indirect heating, which also operates as a desalination unit. The objective was to develop a new cooking pan which could be coupled with a three-stage desalination tower. Thus, the pan could be used for cooking or as the storage tank of the desalination tower. This new pan was installed in a solar cooker with indirect heating and the complete system was tested under field conditions. The sealing was improved, and the system produced more than 5.7L, with electrical conductivity lower than 10ÂS/cm, COP, 1.77 and GOR, 0,35, values consistent with the literature and above the values obtained with the original pan. / Extensivas atividades de pesquisa e desenvolvimento vÃm sendo conduzidas para explorar oportunidades de mÃtodos sustentÃveis e viÃveis de produÃÃo de Ãgua potÃvel utilizando energia solar. Este projeto abrange uma nova configuraÃÃo para o fogÃo solar com aquecimento indireto operar tambÃm como dessalinizador. O objetivo foi desenvolver uma nova panela que pode ser acoplada com uma torre de trÃs estÃgios de dessalinizaÃÃo. Assim, a panela pode ser utilizada tanto para cozinhar ou como o tanque de armazenamento da torre de dessalinizaÃÃo. Esta nova panela foi instalada em um fogÃo solar com aquecimento indireto e todo o sistema foi testado em condiÃÃes de campo. O acoplamento foi otimizado, aumentando a produÃÃo total em relaÃÃo ao projeto anterior. O sistema produziu mais de 5,7L de Ãgua dessalinizada, com condutividade elÃtrica mÃdia abaixo de 10ÂS/cm, COP, 1,77 e GOR 0,35, valores compatÃveis com a literatura e acima dos valores obtidos com a panela original.

In the face of the internationally tightened requirements and regulations for CO2 emissions from the transportation sector, waste heat recovery using a thermoelectric generator (TEG) has become the most significant research interest. A vehicular TEG, converting otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems, is a promising approach for vehicle original equipment manufacturers (OEMs) to reduce fuel consumption and lower CO2 emissions. This thesis aims to explore the main challenges to be faced in the commercialization of TEGs. Based on a review of the literature, four research gaps have been identified, which are respectively: * Translating the material improvements into TEG Performance, * Transient behaviors of vehicular TEGs under driving cycles, * Fuel saving percentage and cost-benefit estimation of TEG, * Bidirectional characteristic of TEM and bifunctional vehicular TEG. To directly address these research gaps, a quasi-static TEM model, a dynamic TEG model, a semi-empirical vehicular TEG model, and a dual-model TEM model have been respectively developed and validated through experiments on both TEM test rigs and TEG engine test benches. These developed models are used as tools to investigate the performance of TEG, parameters sensitivity, and integration effects. Model-based TEG control, TEG cost benefit ratio and feasibility of a bifunctional TEG are also explored based on the developed models. The simulation results show that TEG power generation is highly sensitive to the heat transfer coefficient of hot side heat exchanger and thermal contact resistance. The TEG installation position is identified as the most important integration effect. It has been found by the simulation result that the fuel saving with TEG installed upstream of the three-way catalyst (TWC) is 50% higher than the fuel saving with TEG installed downstream of the TWC. The fuel saving percentage for a skutterudite vehicular TEG, which can generate around 400-600W in constant speed 120km/h, is 0.5-3.6% depending on the integration position in the exhaust line. A 3-minute faster warm-up effect of engine oil can be obtained when the bifunctional TEG works in engine warm-up mode with electrical current applied.

Transport Membrane Condenser (TMC) is an innovative technology based on the property of a nano-scale porous material which can extract both waste heat and water from exhaust gases. This technology tremendously improves the efficiency of boilers and gas/coal combustors by lowering waste heat and increasing water recovery. Contaminants in the flue gases, such as CO2, O2, NOx, and SO2 are inhibited from passing through the membrane by the membrane’s high selectivity. The condensed water through these tubes is highly pure and can be used as the makeup water for many industrial applications. The goal of this research is to investigate the heat transfer, condensation rate, pressure drop and overall performance of crossflow heat exchangers. In this research, a numerical model has been developed to predict condensation of water vapor over and inside of nano-porous layers. Both capillary condensation inside the nanoscale porous structure of the TMC and the surface condensation were considered in the proposed method using a semi-empirical model. The transport of the water vapor and the latent heat of condensation were applied in the numerical model using the pertinent mass, momentum, turbulence and energy equations. By using the proposed model and simulation procedure, the effect of various inlet parameters such as inlet mass flow rate, inlet temperature, and water vapor content of the inlet flow on the performance of the cross-flow TMC heat exchanger was studied to obtain the optimum performance of the heat exchangers at different working conditions. The performance of the TMC heat exchangers for inlet flue gas rate 40 to 120 kg/h, inlet water rate 60 to 140 kg/h, inlet flue gas relative humidity 20 to 90%, and tube pitch ratio 0.25 to 2.25 has been studied. The obtained results show that the water condensation flux continuously increases with the increase of the inlet flue-gas flow rate, water flow rate, and the flue-gas humidity. The total heat flux also follows the same trend due to the pronounced effect of the latent heat transfer from the condensation process. The water condensation flux and the overall heat transfer increase at the beginning for small values of the tube pitches and then decreases as the tube pitch increases furthermore. In addition to the cross-flow TMC heat exchangers, the performance of a shell and tube TMC heat exchanger for high pressure and temperature oxy-combustion applications has been investigated. The performance analysis for a 6-heat exchanger TMC unit shows that heat transfer of the 2-stage TMC unit is higher than the 2-stage with the same number of the heat exchanger in each unit.

Heat recovery steam generators (HRSG) play a very important role in combined cycle (CC) power plants, where steam is generated from a gas turbine exhaust and supplied at the appropriate pressure and temperature to steam turbines for further power generation. The power plants achieve an overall efficiency above 55% and are ideally suited for combined heat and power generation in utility systems. The performance of energy conversion is improved by reducing exergy losses which implies reducing the temperature difference between the combustion gas and the steam cycle. Thus recent HRSG designs include up to three pressure levels with reheat in the steam cycle for maximum energy recovery and the use of high pressure, high temperature superheater and reheater in CC plants. Super critical boilers are also conceivable. Since HRSG performance has a large impact on the overall efficiency of the CC power plant, an accurate simulation of the performance of the HRSG is necessary. We present a steady state HRSG model to support design and rating simulations of vertical units. The simulation model, called FELVAL, divides the boiler in its rows. The row model can also be divided several times following the tube length, to better estimate the fumes temperature distribution across the hot gas path. Another model, called SUFVAL, carries out the design as well as the automatic generation of the FELVAL units and all the needed connections. The log mean temperature difference (LMTD) method and the effectiveness-NTU (ε -NTU) method are alternatively used to compute the overall heat transferred in each part of the HRSG. The problem of convergence of boiler models with more than one row in parallel is discussed. Good initialisation of the different variables is crucial to obtain convergence. The models are tested on 2 references HRSG. The first one is an assisted circulation boiler that operates at 3 subcritical pressure levels. The second is a once through boiler able to operate above the critical pressure of water. These new models were introduced into a commercial software of data reconciliation (VALI of Belsim sa) already used by the engineering and design departments of a HRSG manufacturer. They thus have a general-purpose package enabling them to make design, data reconciliation and simulation with the same software. Moreover, the use of FELVAL model will enable them to simulate any type of boiler and to obtain informations on the change of the temperatures inside the heat exchangers. This information is crucial for well monitoring closely the operation of a boiler, and better understanding its behaviour. This knowledge improvement allows to limit the overdesign and the safety margins and to reduce the investment costs.

Performance of two different waste heat recovery systems (one based on Rankine cycle and the other one using thermoelectricity) combined with non-hybrid, mild-hybrid and full hybrid systems are investigated. The vehicle under investigation was a 440hp Scania truck, loaded by 40 tons. Input data included logged data from a long haulage drive test in Sweden.All systems (waste heat recovery as well as hybrid) are implemented and simulated in Matlab/Simulink. Almost all systems are modeled using measured data or performance curves provided by one manufacturer. For Rankine system results from another investigation were used.Regardless of practical issues in implementing systems, reduction in fuel consumption for six different combination of waste heat recovery systems and hybrid systems with different degrees of hybridization are calculated. In general Rankine cycle shows a better performance. However, due to improvements achieved in laboratories, thermoelectricity could also be an option in future.This study focuses on “system” point of view and therefore high precision calculations is not included. However it can be useful in making decisions for further investigations.

In this thesis, an experimental research is conducted on scroll-based Organic Rankine Cycle (ORC) focusing on the expansion process. An important feature of the ORC is the ability to utilize low or moderate temperature heat sources derived from renewable energy such as concentrated solar radiation, biomass/biofuels combustion streams, geothermal heat and waste heat recovery. The ORC is more appropriate than steam Rankine cycle to generate power from low capacity heat sources (5-500 kW thermal). For example, expansion of superheated steam from 280oC/1000 kPa to a pressure corresponding to 35oC saturation requires a volume ratio as high as 86, whereas for the same operating conditions toluene shows an expansion ratio of 6 which can be achieved in a single stage turbine or expander. The objective of this work is to experimentally study the performance of a selected refrigeration scroll compressor operating in reverse as expander in an ORC. To this purpose, three experimental systems are designed, built and used for conducting a comprehensive experimental programme aimed at determining the features of the expansion process. In preliminary tests the working fluid utilized is dry air while the main experiments are done with the organic fluid R134a. Experimental data of the scroll expander are collected under different operating conditions. Power generation in various conditions is analyzed in order to determine the optimum performance parameters for the scroll expander. In addition, thermodynamic analysis of the system is conducted through energy and exergy efficiencies to study the system performance. Based on the experimental measurements, the optimum parameters for an ORC cycle operating with the Bitzer-based expander-generator unit are determined. The cycle energy and exergy efficiencies are found 5% and 30% respectively from a heat source of 120oC. / UOIT

The Marnoch heat engine (MHE) is a new type of power generation device that is under research and development at the University of Ontario Institute of Technology. In this thesis, the transient heat transfer behaviour of the source heat exchanger of the Marnoch heat engine is studied, and its operation for laminar and turbulent flows is modelled. The temperature variations of the working fluid, the heating fluid and the wall, are calculated. The temperature distribution of the fluids and the wall over the length of the heat exchanger is also calculated. It is found that the temperature of the working fluid rises sharply to a peak and then gradually decreases. The wall temperature decreases exponentially, and the temperature of the heating fluid falls sharply, and then gradually decreases. A base model for the step change in the mass flow of the working fluid is developed and compared against past works for the purpose of validation. / UOIT