This diploma thesis deals with plumbing systems of baking plants v Modřicích. The first part looks for a solution exchange of heat and using waste energy from bakery owens. There are performed several possiblities of projects for plumbing systems. Project part was worked out in cooperation with technical company wich produces equipment for bakery factories. The solution according to relevant standards

The purpose of this thesis is to design a solution thermal power outlet of incinerator in hot water for the supply this town of heat. First and foremost are described problems landfill society and their implications on the environment. Next some alternatives of the waste and the burning in incinerators are described too. The thesis describes the history of the first incineration plant in the Czech Republic and its subsequent upgrading of the economical and environmentally friendly waste recovery and modernization of flue gas cleaning. Contribution of the work is then proposed as amendments to equipment and wiring for use of steam for the conversion heat output into hot water. This is essentially a calculation of steam water heaters at the end of the expansion of the steam and the related adjustments to the turbine blading. At the conclusion outlines the basic economic calculation and comparison of profits and investment associated with this implementation compared to implementation, which is now projected. It is a calculation of investment efficiency and its possible repayment due to higher profits from the sale of energy. This work serves only as a basis work for future technical realization and it outlines the appropriateness of this alteration.

The master Thesis deals with indirect air heating in air handling units. In the theoretical part of the thesis the categories of heat exchangers are defined according to their positioning in ventilation system, used material and type of heat transfer fluid. To the issue of calculating heat exchanges through heat exchangers and description of different kinds of regulation of primary heat transfer fluid is dedicated a separate chapter. The experimental part of the thesis deals with determining performance of current air heat exchanger at set thermal gradient with various heat transfer fluids. In the calculating part of the Thesis, based on measured values, are suggested two possible solutions for use of technological waste heat. Final evaluation of particular solutions was based on the criterion of efficiency usage and implementation investment costs.

This diploma thesis is focused on problems of heat exchangers. There are two main objectives. The first objective is based on long-term measuring of enthalpy heat exchanger, processing of measured data and comparison of result with manufacturer's results. The second objective is design of variant solutions for two types of heat exchanger of air conditioning unit of selected shop. For variant without moisture transportation was selected cross flow exchangers. Thanks to knowledge from long-term measurement, was selected enthalpy heat exchanger for variant with moisture transportation. Chosen variants were compared with emphasis on heat and moisture exchange efficiency with requirements on Ecodesign.

Byggnader i Sverige står för en stor del av landets totala energianvändning och det är därför viktigt att man försöker hitta energieffektiviseringar kring detta område. Ibland kan det vara enklare än man tror att komma på billiga energibesparande lösningar. En självklar sak är att termodynamikens andra lag även gäller avlopp. Eftersom avlopp i hus är öppna system, exponerade mot bistra uteklimatet genom hål eller små skorstenar i taket och det kommunala avloppsystemet, så borde det rimligtvis försvinna värmeenergi från huset även där. Man kan tänka sig att det sker kallras på vintern eller ett luftflöde som drar igenom husets avloppssystem. Detta drag borde kyla ner avloppsystemet. Vi kunde konstatera med hjälp av luftflödesmätare att detta drag på grund av skorstenseffekter ofta är riktat så att det kommer in kall luft från det kommunala avloppssystemet och ut igenom avluftningen på taket. Durgo är ett företag som tillverkar avluftningsventiler. Avluftningsventilen fungerar som så att den bara tar in luft när det blir undertryck i avloppet. Därmed kommer det inte ut någon illaluktande luft från avloppet vilket gör att man kan ha avluftningen installerad inomhus exempelvis på en vind. Om man sätter en avluftningsventil istället för att ha en öppen genomföring via taket sätter man stopp för det drag som kommer från kommunens avloppsnät. Därmed blir det minskad avkylning vid kall väderlek i husets avloppsledningar. Avloppsledningar i hus kan ofta vara oisolerade, även om de kan befinna sig i mer eller mindre isolerade utrymmen så kyler de ner konstruktionen och närliggande rum. Syftet med detta examensarbete är att ta reda på om det går att spara energi med en avluftningsventil. Vi bygger en experimentanläggning för att simulera energiåtgången. Experimentanläggningen består av två isolerade tankar, en luftad med avluftningsventil, den andra med öppen skorsten. Sen gör vi två olika typer av experiment där vi mäter temperaturen i tankarna. Första sättet tittar vi på hur snabbt vatten avkyls i två isolerade tankar där ena tanken är ventilerad som om det vore ett traditionellt avluftat avloppssystem och den andra tanken är ventilerad med en avluftningsventil. Andra sättet jämför vi hur mycket energi det går att upprätthålla en viss temperatur i dessa isolerade tankar. På så sätt kan vi enkelt se om det finns skillnader mellan de olika systemen. Vårt förväntade resultat var att man skulle spara energi om man använde sig av en avluftningsventil. Efter att vi gjort våra experiment kunde man se att vår hypotes mycket väl stämde överens med verkligheten. Vårt experiment visar att ju kallare det är utomhus desto större energibesparing gör man med en avluftningsventil. Energibesparingen kan bli runt 13 kWh per meter avloppsrör och år vilket skulle kunna motsvara 1-2 % per år av den totala uppvärmningskostnaden i ett hus beroende på hur många meter man har. I ett flerbostadshus med 84 lägenheter med 45 % effektgrad av värmeåtervinningen från spillvatten blir energisbesparingen ca 10 000 kWh/år då spillvattentemperaturen höjs med en grad. En avluftningsventil är en mycket billig investering och har dessutom flera andra fördelar än att man sparar energi. Dock måste man tillse att den monteras på rätt sätt så den inte läcker ut avloppsgas. / Buildings in Sweden account for a large proportion of the country’s total energy consumption and it is therefore important to try and find energy efficiencies around this area. Sometimes it can be easier than you think to get cheap energy saving solutions. One obvious thing is that the second law of thermodynamics also applies for sewerage. Because the sewage in houses are open systems, exposed to the harsh outdoor climate through holes or small chimneys on the roof and the municipal sewer system, then it should be reasonable that heat energy disappears from the house too. One could imagine that there are cold drafts in the winter or an airflow that pulls through the building's drainage system. This flow should cool down the drains. We could conclude with the aid of an airflow meter that these flows because of the chimney effects often are directed so that cool air flows from the municipal sewage system and out through the vent on the roof. Durgo is a company that manufactures air admittance valves. This valve works so that it only takes in air when under pressure in the sewer system. Thus, it will not print any foul air from the sewer which means that you can have the vent installed indoors, for example in an attic. If you put an air admittance valve instead of having an opening through the roof you put a stop to this airflow. Thus it becomes reduced cooling during cold weather in sewer systems. Drainage pipes in houses are often uninsulated, although they can be in more or less isolated areas and could cool down the construction and nearby rooms. The purpose of this thesis is to find out if it is possible to save energy with an air admittance valve. We built an experimental facility to simulate the energy consumption. The experimental facility consists of two insulated tanks, aerated with an air admittance valve, the other with an open chimney. Then we make two different types of experiments in which we measure the temperature in the tanks. First way, we look at how quickly the water is cooled down in two insulated tanks where one tank is vented as if it were a traditional vented sewer system and the second tank is ventilated with an air admittance valve. Second way, we compare how much energy it is possible to maintain at a certain temperature in the insulated tanks. In this way, we can easily see if there are differences between the various systems. Our expected results were that youwould save energy if you used an air admittance valve. After we made our experiments we could see that our hypothesis very well matched reality. Our experiment shows that the colder it is outside, the greater energy savings you do with an air admittance valve. Energy savings can be around 13 kWh per meter sewer pipe and year, which could equate to 1-2% per year of the total heating cost of a house depending on how many meters you have. In an apartment building with 84 apartments with 45% power level of heat recovery from waste water, the energy saving will be about 10 000 kWh / year because the waste water temperature becomes one degree higher. An air admittance valve is a very cheap investment and it offers several benefits beyond saving energy. However, one must ensure that it is installed properly so it does not leak emission.

Tillskottsvatten i avloppsledningsnät medför stora kostnader i form av underhåll,ökad mängd kemikalier och energi som även belastar miljön. Syftet med detta examensarbetevar att få ökad förståelse av temperaturförhållanden mellan spillvattenoch mark för att förbättra modelleringen av tillskottsvatten. Hypotesen är att spillvattentemperaturensjunker vid inläckage då temperaturen på tillskottsvattnet ärlägre än spillvattnet. Ett spillvattenrör med en längd på ungefär 2,5 km i Umeåundersöktes med givare jämt fördelade längs sträckan. Metoden innebar att medmätvärden på temperaturerna för spillvattnet, luften i spillvattenröret och i markentillsammans med flödet och nivån på spillvattnet modellera värmeutbytet i COMSOLMultiphysics. Resultatet gav fyra liknande funktioner för både spillvattenregionenoch luftregionen som beskrev värmeutbytet mellan spillvattenröret och marken.Effektutbytena hade en linjär tendens som funktion av temperaturdifferensen mellanspillvatten och mark under mätperioden fram till maj månad men med en högspridning då effektutbytet är även beroende på flödet och inte bara temperaturdifferensen.Majoriteten av effektutbytet var mellan ytan på spillvattenröret ochspillvattnet. I regionen mellan luft och yta på spillvattenröret så var majoriteten aveffektutbytet ifrån strålningsutbytet mellan spillvattnet och ytan. Resultaten gaväven U-värden för regionen mellan spillvattenregionen och luftregionen i rörledningenoch dessa var omkring 4 W/(m2K) respektive 0,8 W/(m2K). Tillskottsvattnetmodellerades utifrån värmeutbytet och det visade på ökade flödesnivåer när det varvåtperioder med en noggrannhet på ± 1 kg/s. / Supplemental water in the sewer network entails large costs in the form of maintenance,increased amounts of chemicals and energy that also have a burden on theenvironment. The purpose of this thesis was to gain an increased understandingof temperature conditions between wastewater and soil to improve the modelingof supplemental water. The hypothesis is that the waste water temperature dropswhen leakage occurs and when the temperature of the additional water is lower thanthe wastewater. A wastewater pipe with a length of approximately 2.5 km in Umeåwas examined with sensors evenly distributed along the path. The method involvedmodeling the heat flow in COMSOL Multiphysics with measured values of thetemperatures for the wastewater, the air in the wastewater pipe and in the groundtogether with the flow and the level of the wastewater. The result gave four similarfunctions for both the wastewater region and the air region that described the heattransfer from the wastewater pipe to the ground. The heating effects had a lineartendency as a function of the temperature difference between wastewater and soilduring the measurement period up to the month of May, but with a high spread asthe heat transfer is also dependent on the flow and not just the temperature difference.The majority of the heat transfer was between the surface of the wastewaterpipe and the wastewater. In the region between the air surface on the wastewaterpipe, the majority was the heat transfer from the radiation between the wastewaterand the surface. The results also gave U-values for the wastewater region and theair region in the pipeline and these were around 4 W/(m2K) and 0.8 W/(m2K),respectively. The supplemental water was modeled on the basis of the heat transferand it showed increased flow levels when it was wet periods with an accuracy of ±1 kg/s.

The subject of this dissertation is the design of an air conditioning system for a family house. The design contains the actual state, in which a central unit with variable air volume regulators and air supply adjustment is designed. The first version of optimisation offers a simple central ventilation, and in the second version a decentral ventilation for the object. These options were compared based on their purchasing price and additionally from the interior comfort feel point of view. In the next part a long-term measurement of an energy recovery ventilation was performer, and data was processed to evaluate and compare the efficiency with efficiency promised by producer.

In this thesis, we study the phenomenon of thermally induced polarisation using a combination of theory and computer simulation. Molecules of sufficiently low symmetry exhibit thermo-molecular orientation when subjected to a temperature gradient, leading to considerable electrostatic fields in polar liquids. Here, we first use non-equilibrium molecular dynamics simulations to study this interesting effect numerically. To this end, we propose an integration algorithm to impose a constant heat flux in simulations and show that it greatly improves energy conservation compared to a previous algorithm. We next investigate the thermal polarisation of water and find that truncation of electrostatic interactions can lead to severe artefacts, such as the wrong sign of polarisation and an overestimation of the electric field. We further show that the quadrupole-moment contribution to the electric field is significant and responsible for an inversion of its sign. To facilitate the theoretical description of electrostatic interactions, we propose a new dipolar model fluid as a perturbation of a Stockmayer fluid. Using this modified Stockmayer model, we provide numerical evidence for the recently proposed phenomenon of thermally induced monopoles. We show that the electrostatic field generated by a pair of heated/cooled colloidal particles immersed in such a solvent can be trivially described by two Coulomb charges. Finally, we propose a mean-field theory to predict the thermo-polarisation effect exhibited by our model fluid theoretically, and demonstrate near quantitative agreement with simulation results.

科学研究費補助金 研究種目:一般研究(B) 課題番号:06452428 研究代表者:松田 仁樹 研究期間:1994-1995年度

La préservation de la chaîne du froid est un paramètre particulièrement important dans le cadre de la distribution urbaine, où les fréquentes ouvertures de portes induisent une charge thermique d’infiltration. Afin de réduire les transferts de masse et de chaleur et de protéger l’ouverture, des rideaux d’air ont récemment été installés au niveau de l’ouverture des camions frigorifiques. L’objet de la présente étude est d’étudier ce type confinement. Deux modèles CFD ont été développés pour simuler les champs de températures et de vitesses dans un camion réfrigéré clos. Ils ont permis de montrer que la variation de la vitesse de soufflage ne modifie pas de manière significative la structure des écoulements. Différents conduits d’air sont modélisés. Les résultats numériques montrent que la configuration avec un conduit ouvert améliore fortement le renouvellement d’air. Puis, une étude numérique est réalisée dans le but d’étudier les infiltrations de chaleur et de masse au cours de l’ouverture des portes. Ces écoulements sont bien prédits par le modèle CFD, excepté à la transition entre les deux régimes d’infiltration. Une caisse expérimentale a été équipée d’un dispositif de rideau d’air composé d’un jet ambiant, d’un jet froid ou d’un jet double. En parallèle, un modèle numérique CFD a été développé pour étudier l’influence de différents paramètres. Une bonne concordance entre les résultats numériques et expérimentaux a été observée. L’efficacité du rideau d’air ambiant est maximale lorsque le point d’impact du rideau se situe dans le plan de l’ouverture. Le rideau double maintient efficacement l’homogénéité de la température pour de courtes ouvertures. Le rideau d’air froid est la meilleur configuration, il limite fortement l’augmentation de température de l’enceinte et permet des gains énergétiques importants. / Cold chain safety is a key parameter for urban distribution where the frequent door-opening induces a heat infiltration. In order to reduce heat and mass transfer, air curtain have recently been installed to protect the doorway of refrigerated truck. The aim of this work is to study this type of door insulation. Two CFD numerical models were developed to simulate the temperature and velocity fields in a closed refrigerated truck. These models showed that modifying the blowing velocity does not modify the air flow structure inside the cavity. Different air chutes were modelled. Numerical results demonstrate that the configuration with a convergent and an open duct strongly improves the air renewal. A numerical investigation was performed in order to study heat and mass infiltration rates during the opening. The infiltration flow rate is well predicted by the CFD model, except at the transition between both flow regimes. An experimental truck was equipped with an air curtain setup, composed by an ambient air jet, a cold air jet or a double jet. In parallel, a numerical CFD model was developed to study the influence of various parameters. Experimental and numerical results were found to be in good agreement. The maximum efficiency of the ambient air curtain is reached when the impact point of the jet occurs in the door plane at the ground level. This configuration is only relevant for short opening times. The double air curtain efficiently maintains the temperature homogeneity for short openings. The cold air curtain is the best configuration which strongly limits the temperature increase during the opening and allows important energy savings.