Fernwärme ist aufgrund der verstärkten Förderung der Bundesregierung in den letzten Jahren wieder stärker in den Fokus der Energiewirtschaft gerückt. In Hinblick auf einen wirtschaftlich und energetisch effizienten Betrieb von Fernwärmesystemen ist nicht nur der Einsatz der Wärmeerzeuger mittels einer Einsatzplanung sorgfältig zu organisieren, sondern auch das Betriebsverhalten des Wärmeverteilnetzes selbst zu berücksichtigen. So führen ständig auftretende Änderungen der thermischen Last, der Vorlauftemperatur am Einspeisepunkt oder der Rücklauftemperaturen der Abnehmer zu instationären Betriebszuständen im Fernwärmenetz. Die damit verbundene zeitliche Entkopplung der zentralen Wärmeeinspeisung von der dezentralen Wärmeentnahme induziert eine Speicherung thermischer Energie in dem in den Rohrleitungen befindlichen Wasser und in den Rohren selbst. In den seltensten Fällen wird dieser Vorgang der Wärmespeicherung aktiv genutzt, er tritt vielmehr als eher unerwünschter Nebeneffekt auf. Bei Kenntnis der thermodynamischen Zusammenhänge hingegen lässt sich das Fernwärmenetz durch zielgerichtete Steuerung der Vorlauftemperatur analog einem thermischen Heißwasserspeicher als Wärmespeicher nutzen. Dies ist wiederum für die Betriebs- und Gewinnoptimierung interessant, da so weitere Speicherkapazitäten nutzbar gemacht werden können, um Lastspitzen zu verschieben und KWK-Anlagen zu betreiben ohne zusätzliche Investitionen tätigen zu müssen. In dieser Arbeit wird eine Methode vorgestellt, in der die Netzspeicherleistung mit Hilfe eines thermo-hydraulischen Simulationsprogrammes bestimmt wird, wobei dynamische Effekte wie die veränderliche Vorlauftemperaturen am Einspeisepunkt oder die stark schwankenden Lastanforderungen der Abnehmer in der Berechnungsmethodik realitätsnah abgebildet werden. Für eine aktive Nutzung des Fernwärmenetzes als Wärmespeicher muss der Verlauf der Vorlauftemperatur an die jeweilig gewünschte Netzspeicherleistung angepasst werden. Dazu wird in dieser Arbeit ein vereinfachter Funktionsansatz für die Netzspeicherleistung bestimmt, der zunächst mittels Regressionsanalyse aus den Ergebnissen gezielter thermo-hydraulischer Simulationen ermittelt und anschließend so in eine Einsatzplanung integriert wird, sodass die Vorlauftemperatur als zu optimierende Variable in die Gesamtoptimierung einfließt. Anhand eines realen Anwendungsfalls werden die Möglichkeiten und Grenzen der aktiven Nutzung der Speicherfähigkeit von Fernwärmenetzen aufgezeigt. Insbesondere werden monetäre Gewinnpotentiale bei Anwendung der aktiv gesteuerten Netzspeicherung in durch KWK-Anlagen versorgten Fernwärmenetzen bei gleichzeitigem Stromhandel auf dem Spotmarkt abgeschätzt.

Selecting a suitable power source, during the design process, for a stand-alone soya business unit is challenging and complex. Especially with the aim of optimizing electrical and thermal energy, as well as minimizing the life cycle cost. During the design and development of a soya business unit it was realized that a design tool is needed to assist with the decision making process when selecting a power source. Waste heat can be recovered from either or both the exhaust gas and cooling system of the power source and can be utilized in the soya process. Research of available literature revealed no design tool to assist with the decision making process of the stand-alone business unit and consequently lead to this study. This dissertation presents different possible power sources that could be utilized in supplying energy to the business unit, as well as design tools available. Advantages and disadvantages of the different power sources are discussed. The shortfalls of a number of the available design tools are also discussed. A diesel generator set was selected as the preferred power source for the business unit. Criteria for this selection included the price per kWhe generated, the ease of maintenance, the availability of the diesel generators in rural areas and the availability of diesel as a fuel. The diesel engine was characterized through experimental work for a more in depth understanding of the energy profile of the engine at part load conditions. These results were used as guidelines in the development of the design tool. The design tool was developed with the aim of being user friendly and versatile. The time intervals of the required load of the business unit are flexible. Different types of power sources and fuels can be used within the design tool. User defined heat exchangers are utilized to calculate the possible heat recovery from the power source. The design tool matches the available energy of different power sources at part load conditions with the required load profile of the soya business unit. It then eliminates power sources that would not be able to deliver the minimum required energy. The running cost is calculated for each of the remaining power sources and the power source with the minimum annualized cost, which includes capital cost, maintenance cost and fuel cost, is suggested. The design tool was verified against a base load condition of the soya business unit and the suggested power source showed a saving of 31,4% in electrical energy, an increased overall efficiency of 24,9% and a saving in annualized cost of 27,3%. The design tool can be used to optimize specific components and design options within a combined heat and power system. Sensitivity analysis can be performed with the design tool to determine various influences on the designed system. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2008.

Oförmåga att minska utsläppen av växthusgaser i tillräckligt takt för att undvika en alltför kraftig global uppvärmning har motiverat framtagandet av tekniker med potential att minska mängden koldioxid i atmosfären. En av dessa tekniker är bioenergi med koldioxidlagring (Bio-energy with carbon capture and storage, BECCS), där koldioxid avskiljs från punktkällor med biogena utsläpp och lagras i geologiska strukturer. Även biokol tillsatt till jordbruksmark har potential att bidra till negativa utsläpp. Både svenska och internationella strategier inkluderar negativa utsläpp för att uppfylla förpliktelserna i Parisavtalet. För att säkerhetsställa att teknikerna lever upp till potentialen krävs ett livscykelperspektiv där klimatpåverkan beräknas på systemnivå. En livscykelanalys utfördes, där klimatpåverkan vid utnyttjande av grenar och toppar (GROT) från den svenska skogsindustrin beräknades för teknikerna BECCS och biokol tillsatt till jordbruksmark. Teknikerna jämfördes med ett referensscenario där GROT förbränns i ett kraftvärmeverk för att producera el och fjärrvärme utan omhändertagande av koldioxid som bildas vid förbränning. Resultaten visar att BECCS har potentialen att bidra med negativa utsläpp på mellan -168 och -666 kg CO2-ekvivalenter/ ton GROT torrsubstans (TS). Då GROT-skörden ökar till 80% av den årliga avverkade arealen skog i Sverige och kombineras med gallring, resulterar 666 kg CO2-ekvivalenter/ ton GROT TS, i 4,4 miljoner ton CO2-ekvivalenter per år. Detta motsvarar 25,8 % av klimatpåverkan från inrikestransporter i Sverige år 2016. Nettoutsläppen från biokol tillsatt till jordbruksmarker, varierar mellan 934 och -344 kg CO2-ekvivalenter/ ton GROT TS. Då GROT-skörden ökar till 80% av den avverkade arealen skog i Sverige och kombineras med gallring, resulterar 344 kg CO2-ekvivalenter/ton GROT TS i 2,2 miljoner ton CO2-ekvivalenter. Detta motsvarar 13,3 % av klimatpåverkan från inrikes transporter i Sverige år 2016. Båda teknikerna har potential att åstadkomma nettonegativa växthusgasutsläpp, men resultaten är beroende av klimatpåverkan från ersättande el- och fjärrvärmeproduktion. / The inability to achieve sufficient reduction of greenhouse gas emissions has led to the development of techniques with potential to achieve negative greenhouse gas emissions. One of these techniques is called Bio-energy with carbon capture and storage (BECCS), where carbon dioxide is captured from biogenic point sources with biogenic emissions and stored underground. Biochar applied to farmland is another technique with potential to achieve negative greenhouse gas emissions. Both Swedish and international strategies, to meet the obligations in the Paris Agreement, include negative greenhouse gas emissions. A life cycle approach is required to ensure that the techniques deliver on the promise of negative emissions. A Life cycle assessment was conducted where the global warming potential was calculated for BECCS and biochar added to farmland in two different scenarios where tops and branches (GROT) from the Swedish forest industry were used as feedstock. The techniques were compared to a reference scenario where GROT were used in a combined heat and power plant (CHP-plant). The results show that BECCS has the potential to achieve net negative emissions of between -168 and -666 kg CO2-equivalents/ tonne GROT dry matter (DM). When GROT is harvested from 80% of the yearly final felling areas in Sweden and combined with thinning, 666 kg CO2-equivalents/ Mg GROT DM is equivalent to in 4,4 million ton CO2-equivalents per year. This corresponds to 25,8 % of Sweden's greenhouse gas emissions from domestic transportation in 2016. The results of greenhouse gas emissions from biochar applied to farmland varied between 934 to -344 CO2-equivalents/ Mg GROT DM. When GROT is harvested from 80% of final felling areas in Sweden and combined with thinning, -344 CO2-equivalents/ Mg GROT DM is equivalent to 2,2 million ton CO2- equivalents per year. This corresponds to 13,3 % of Sweden's greenhouse gas emissions from domestic transportation in 2016. Both techniques have the potential to achieve net negative greenhouse gas emissions. However, the results are greatly influenced by the climate impact from generating the electricity to replace the losses in electricity production when GROT is used for BECCS and biochar instead of in a CHP-plant.

Fossil fuels are the major sources of electrical power generation in the world. Among all fossil fuels, oil is considered as the most sought-after fuel. The burden on countries that provide subsidized electricity produced from oil-fired power plants is noteworthy. Kuwait is a notable example of these countries. Electricity in Kuwait is heavily consumed by residential air conditioning, which comprises 60% of the total electricity generated at peak times on a hot summer day. From this perspective, residential air conditioning in Kuwait was selected to undergo further investigation regarding low energy air conditioning choices. Three solutions to control the rapid growth of demand for electricity by residential air conditioning are examined. The first solution investigated assesses the orientation and grouping of houses in Kuwait in order to examine their effect on cooling load and electrical energy consumption for future houses. Four residential cases were developed; each case comprises six typical houses. The cases identified are: (1) single block facing east-west, (2) single block facing north-south, (3) double block facing east-west and (4) double block facing north-south. Cooling loads are calculated using the DesignBuilder building thermal simulation software. Case (2) is found to have the smallest cooling load, and case (1) the largest. The estimated savings from applying case (2) compared to the average of the four cases for the future houses planned to be built by the government by the year 2016 (i.e. approximately 20,000 houses) are found to be approximately .US 33 million of power system capital costs, 15 GWh per year of electrical energy consumption and 11 kilotons per year of CO2 emissions. In the second solution, a lifecycle cost analysis is performed to evaluate the economic feasibilities of electricity driven chilled water system compared to predominant air conditioning system in Kuwaiti houses which is Packaged- Direct Expansion. The study considers the total cash paid by the consumer and the total cash paid by the government, since electricity is subsidized in Kuwait. The study finds that the chilled water system is not cost-effective for consumers due to high installation cost. However, a chilled water system would be cost-effective for the government because it consumes 40%less electrical energy than Packaged-DX. So, the study suggests subsidising the installation of chilled water systems so that the installation cost to the consumer is the same as for Packaged-DX systems. In the third solution, the study examines the viability of a single-effect LiBr absorption chiller driven by steam extracted from the steam turbine in the configuration of a combined cycle power plant (CCPP). The analysis shows that CCPP with absorption chiller yields less net electrical power available to utility grid compared to similar CCPP giving electricity to the grid and to Direct-Expansion air conditioning systems for the same cooling requirements. The reasons for that are the reduction in steam turbine power output resulted from steam extraction, and the amount of electrical energy required to operate the configuration of CCPP with absorption chiller.

The EU energy efficiency directive is driving the EU member states to set ambitious goals to increase energy efficiency. Mälarenergi AB is one of the Swedish energy companies, affected by the directive, that have taken an active role in order to increase efficiency within their energy production. This study was initiated to perform energy analysis and find energy optimization measures in the systems attached to one of Mälarenergi’s CHP-units, called P5.The operating conditions of the bio fueled combined heat and power plant, P5, recently changed when the connected boiler, P4, was decided to be shut down. The two boilers shared turbine, steam, feed water, condensate and oil systems, and the operating conditions of these systems changed radically when the mass flow decreased as P4 was shut down. The changed operating conditions affects the efficiency and the performance of the plant. The changed mass flow affects the capacity demands, efficiency in components and the technical conditions of the plant.The general approach through this thesis and the used methodology is based on initial analysis of the system changes, review of the necessary functions in the system and identification of the differences between the needed functions and the existing system. Optimization potential were identified where there were large differences and as a final step, technical and economic feasibility of implementing identified optimization measures was analyzed. The results shows that feasible optimization potential is identified in removing pumps without adjustable speed drives from the system, installing adjustable speed drives to the warm condensate pumps, replacing the dilution water pumps and detaching the atomization steam tank for P4. The economic feasibility to invest in a new direct heater, better adjusted to the operating conditions of P5, is small but could be an option to Mälarenergi if the alternative production cost remains high. Without the already installed adjustable speed drives in Mälarenergi’s plant the efficiency of the operations would be much lower than what it is today and the optimization potential essentially larger. The efficiency potential in the plant increases further when the attached turbine, G4, is to be dismantled and the operating conditions changes again. More extensive simplifications and rearrangements of the system can be made to decrease the energy demand for operations with 745 MWh/year. / EU:s energieffektiviserings direktiv ställer hårda krav på företag i medlemsländerna att kartlägga och analysera energiförbrukning för att identifiera åtgärder för att öka effektivitet. Utöver detta så har Sverige ambitiösa mål om ökad energieffektivitet i samtliga sektorer. Att effektivisera energiproduktionsanläggningar för att hitta effektiviseringspotential är därför aktuellt för svenska energiproducenter. Mälarenergi är ett av de energiföretag som arbetar aktivt med att kartlägga och minska sin energiförbrukning. Studien har därför genomförts för att granska panna 5 i Västerås kraftvärmeverk, för att undersöka hur energieffektiviseringsåtgärder kan identifieras i kraftvärmeprocesser där driftförutsättningar och processer har förändrats. Panna 5 har flertalet gemensamma processer med en äldre panna i anläggningen, panna 4, vars drift har upphört och pannan ska läggas ner. Driftförhållandena i de tidigare gemensamma systemen för kondensat, matarvatten, kylning och olja har därför förändrats och massflöden i systemen minskat kraftigt. De förändrade förhållandena och massflödena påverkar kapacitetsbehovet i systemen, effektiviteten i flertalet komponenter samt de tekniska kraven som ställs på panna 5. Den största förändringen i systemet är de minskade massflödena. Flödet i kondensatsystemet har minskat från ca 100 kg/s till 45 kg/s. Samma förändring i matarvattensystemet då panna 4 kopplas bort, är från 160 kg/s till 50 kg/s. Studien visar att det finns energieffektiviseringspotential i att byta ut pumpar vars pumpdrift har påverkats kraftigt, upphöra med drift av pumpar utan frekvensstyrning, installera frekvensstyrning på pumpar där flöden varierar samt förenkla och ta bort överflödiga processer som inte nyttjas vid de nya förhållandena. Processerna kan också optimeras genom att investera i en ny direktvärmare bättre lämpad för panna 5, dock är lönsamhetskalkylen för denna svag och ytterligare bedömning krävs. Resultatet visar även att då turbinen till panna 5 är uttjänt och nedmonteras så kan processerna kring panna 5 förenklas ytterligare och optimeras så pass att 745 MWh el för drift av pannan kan sparas varje år. Generellt kan det konstaterats att även förvärmare, matarvattentank och värmeväxlare är överdimensionerade när flödet i systemet minskar, kostnads-och energibesparingen för att byta ut dessa komponenter är dock negativa, eftersom komponenterna själva inte förbrukar någon energi. Att ha för stora kapaciteter i värmeväxlare bör snarare ses som en möjlighet, att kartlägga kapacitetsbehovet underlättar dock underhållsplanering i systemet. Den generella metoden som användes i studien bygger på modellen att först kartlägga de genomförda förändringarna i systemen, fastställa funktionskraven i det nya systemet och därefter analyserna skillnaderna mellan de fastställda funktionskraven och den befintliga tekniken. Optimeringspotential kan därefter identifieras där dessa två skiljer sig till stor del. Därefter utvärderas optimeringsåtgärden genom kvantitativ analys och investeringskalkylering.

The thesis examines the suitability of a CHP project in Bystřice nad Pernštejnem, a small town in Vysočina region, Czech Republic, which is currently supplied by biomass central heating. It reviews situation and availability of renewable energy sources and opportunities for CHP both in the Czech Republic and in Europe, including the context of current global developments. The opening chapters are followed with the renewable energy project for Bystřice nad Pernštejnem itself. The current technology, availability of biomass fuel for a potential future project, and possible development of energy sources in the town are analysed. Three alternative solutions for the CHP plant are suggested, with proposal for the technology and economic analysis, and possible future steps of the town council are discussed.

In some applications, the piston steam engine may be more suitable than the technology currently used. The thesis deals with the analysis of its advantages, weaknesses and possibilities of use, which are offered. Introduces the principles and functions of piston steam engines. It also contains a thermodynamic design based on a specific assignment and a feasibility assessment.

Small domestic hot water boilers burning solid fuels represent a significant source of air pollu-tion. It is therefore an effort to increase their combustion efficiency and to reduce the produc-tion of harmful emissions. For this reason, the operation of older and currently unsatisfactory types of household boilers has been legally restricted. Preferred types of boilers are low-emission boilers, especially automatic or gasification boilers. Most of them, however, in compar-ison with previous types of boilers, also require connection to the electricity grid. If there is a long-term failure in electricity grid, the operation of newer boiler types is limited. Wood and coal gasification boilers are currently available on the market and can be operated even in the event of a power failure, but only in heating systems with natural water circulation. In heating systems with forced water circulation, these boilers, fireplaces or fireplace inserts with hot-water heat exchangers cannot be operated without external battery supply in the event of a power failure. The dissertation thesis therefore deals with the question of whether it would be possible by thermoelectric conversion of waste heat of flue gases of small-scale low-emission combustion hot water domestic boilers to obtain sufficient electricity, to power supply their circulation pumps and to ensure operation in systems with forced water circulation independently of elec-tricity supply from the grid. In order to answer this question, a simulation tool predicting the power parameters of ther-moelectric generators was created. Compared to previously published works, the calculations and simulations include the influence of the generator on the boiler flue gas functionality. To verify the simulation tool, an experimental thermoelectric generator was built using the waste heat of the flue gas of an automatic hot water boiler for wood pellets. In addition to this genera-tor, there was also created an experimental thermoelectric fireplace insert and other equipment related to these experiments.

This master’s thesis deals with the design of a heat recovery steam generator. The introductory part of the thesis is dedicated to waste heat boilers, their division and their utilization in combined cycles gas turbine. In the following chapter, an analysis of the existing combined heat and power plant operation is performed. In the next part of the thesis, the conceptual layout of the new source is designed. Subsequently, the thermal calculation of the boiler is carried out as well as the design of individual heat exchanging surfaces. The sixth chapter deals with the strength calculation of the boiler and the outer piping, chambers and drum are designed here. At the end of the thesis there are described off-design states of the new combined cycle gas turbine.

The final thesis deals with the heating of the hospital building and preparation of the domestic hot water by cogeneration unit. The building will be largely heated by plate radiators. As a heat source is used a cogeneration unit with combustion engine. The project deals with the design dimensioning and connection of these parts.