No description available.

Urban areas contain significant amounts of asphalt pavement. When exposed to the sun, asphalt pavement absorbs solar radiation and stores it as thermal energy raising its temperature. According to the urban heat island effect (UHIE), the pavement releases the thermal energy back to the surrounding air resulting in a rise in local air temperature. A pipe network containing a passing fluid installed in the pavement can reduce the UHIE. The fluid captures the thermal energy stored in the pavement, reducing air and pavement temperatures as well as providing heated water for other applications. The heat transfer/harvesting system can be optimized to produce the desired cooling of the pavements. This research addresses the economic feasibility of a pipe network by design as well as structural performance through computer modeling. To design the pipe network and predict its economic feasibility an Excel spreadsheet was programmed. It requires local air temperature data to determine the yearly temperature profile within the pavement and to calculate the amount of thermal energy that could be extracted. By varying design parameters such as fluid flow rate, it produces a matrix of payback periods. Structural conditions were considered for the installation of the proposed system. To simultaneously evaluate the thermal and structural performance of the pipe network installation, a finite element model was created using COMSOL Multiphysics©. A typical value of solar radiation and a standard truck tire wheel load were applied to the model to simulate the intended application of the pipe network. The result of this thesis is a method and a tool to design and analyze with respect to economic and structural performance a pipe network used to extract the thermal energy stored in asphalt pavements and reduce the UHIE.

District Cooling Systems (DCS) have been widely applied in large institutions such as universities, government facilities, commercial districts, airports, etc. The hydraulic system of a large DCS can be complicated. They often stem from an original design that has had extensive additions and deletions over time. Expanding or retrofitting such a system involves large capital investment. Consideration of future expansion is often required. Therefore, a thorough study of the whole system at the planning phase is crucial. An effective hydraulic model for the existing DCS will become a powerful analysis tool for this purpose. Engineers can use the model to explore alternative system configurations to find an optimal way of accommodating the DCS hydraulic system to the planned future unit. This thesis presents the first complete procedure for the use of commercial simulation software to construct the hydraulic model for a large District Cooling System (DCS). A model for one of the largest DCS hydraulic systems in the United States has been developed based on this procedure and has been successfully utilized to assist its master planning study.

Thermal energy storage systems as an integral part of concentrated solar power plants improve the performance of the system by mitigating the mismatch between the energy supply and the energy demand. Using a phase change material (PCM) to store energy increases the energy density, hence, reduces the size and cost of the system. However, the performance is limited by the low thermal conductivity of the PCM, which decreases the heat transfer rate between the heat source and PCM, which therefore prolongs the melting, or solidification process, and results in overheating the interface wall. To address this issue, heat pipes are embedded in the PCM to enhance the heat transfer from the receiver to the PCM, and from the PCM to the heat sink during charging and discharging processes, respectively. In the current study, the thermal-fluid phenomenon inside a heat pipe was investigated. The heat pipe network is specifically configured to be implemented in a thermal energy storage unit for a concentrated solar power system. The configuration allows for simultaneous power generation and energy storage for later use. The network is composed of a main heat pipe and an array of secondary heat pipes. The primary heat pipe has a disk-shaped evaporator and a disk-shaped condenser, which are connected via an adiabatic section. The secondary heat pipes are attached to the condenser of the primary heat pipe and they are surrounded by PCM. The other side of the condenser is connected to a heat engine and serves as its heat acceptor. The applied thermal energy to the disk-shaped evaporator changes the phase of working fluid in the wick structure from liquid to vapor. The vapor pressure drives it through the adiabatic section to the condenser where the vapor condenses and releases its heat to a heat engine. It should be noted that the condensed working fluid is returned to the evaporator by the capillary forces of the wick. The extra heat is then delivered to the phase change material through the secondary heat pipes. During the discharging process, secondary heat pipes serve as evaporators and transfer the stored energy to the heat engine. Due to the different geometry of the heat pipe network, a new numerical procedure was developed. The model is axisymmetric and accounts for the compressible vapor flow in the vapor chamber as well as heat conduction in the wall and wick regions. Because of the large expansion ratio from the adiabatic section to the primary condenser, the vapor flow leaving the adiabatic pipe section of the primary heat pipe to the disk-shaped condenser behaves similarly to a confined jet impingement. Therefore, the condensation is not uniform over the main condenser. The feature that makes the numerical procedure distinguished from other available techniques is its ability to simulate non-uniform condensation of the working fluid in the condenser section. The vapor jet impingement on the condenser surface along with condensation is modeled by attaching a porous layer adjacent to the condenser wall. This porous layer acts as a wall, lets the vapor flow to impinge on it, and spread out radially while it allows mass transfer through it. The heat rejection via the vapor condensation is estimated from the mass flux by energy balance at the vapor-liquid interface. This method of simulating heat pipe is proposed and developed in the current work for the first time. Laboratory cylindrical and complex heat pipes and an experimental test rig were designed and fabricated. The measured data from cylindrical heat pipe were used to evaluate the accuracy of the numerical results. The effects of the operating conditions of the heat pipe, heat input, and portion of heat transferred to the phase change material, main condenser geometry, primary heat pipe adiabatic radius and its location as well as secondary heat pipe configurations have been investigated on heat pipe performance. The results showed that in the case with a tubular adiabatic section in the center, the complex interaction of convective and viscous forces in the main condenser chamber, caused several recirculation zones to form in this region, which made the performance of the heat pipe convoluted. The recirculation zone shapes and locations affected by the geometrical features and the heat input, play an important role in the condenser temperature distributions. The temperature distributions of the primary condenser and secondary heat pipe highly depend on the secondary heat pipe configurations and main condenser spacing, especially for the cases with higher heat inputs and higher percentages of heat transfer to the PCM via secondary heat pipes. It was found that changing the entrance shape of the primary condenser and the secondary heat pipes as well as the location and quantity of the secondary heat pipes does not diminish the recirculation zone effects. It was also concluded that changing the location of the adiabatic section reduces the jetting effect of the vapor flow and curtails the recirculation zones, leading to higher average temperature in the main condenser and secondary heat pipes. The experimental results of the conventional heat pipe are presented, however the data for the heat pipe network is not included in this dissertation. The results obtained from the experimental analyses revealed that for the transient operation, as the heat input to the system increases and the conditions at the condenser remains constant, the heat pipe operating temperature increases until it reaches another steady state condition. In addition, the effects of the working fluid and the inclination angle were studied on the performance of a heat pipe. The results showed that in gravity-assisted orientations, the inclination angle has negligible effect on the performance of the heat pipe. However, for gravity-opposed orientations, as the inclination angle increases, the temperature difference between the evaporator and condensation increases which results in higher thermal resistance. It was also found that if the heat pipe is under-filled with the working fluid, the capillary limit of the heat pipe decreases dramatically. However, overfilling of the heat pipe with working fluid degrades the heat pipe performance due to interfering with the evaporation-condensation mechanism. / Mechanical Engineering

The solution of the undergoing climate and energy crises requires a radical transformation of the energy system, in which sustainability, no carbon emissions and energy efficiency ought to play a paramount role.  This revolution should extend to all areas of the energy system, including the space heating and cooling sector, which accounts for a third of the European final energy demand and, in the European continent, it is still mostly supplied by fossil fuels. District heating is a simple but powerful technology that can contribute to tackle this challenge. As a network infrastructure, it is characterised by the flexibility of the heat production, allowing the incorporation of a wide range of heat sources over time. Furthermore, it enables the recycling of heat that would otherwise be wasted and the use of local heat sources in a more cost-effective manner. Moreover, its coupling with the electricity sector can facilitate the increase of intermittent electric renewable energy sources.  Nevertheless, at the moment, district heating only covers a tenth of the European space heating and cooling needs, albeit with significant differences among countries. In addition, the development of new district heating networks is capital intensive and can only be justified in those areas where the concentration of the heat demand is sufficiently high to deliver a lower cost to society than an individual alternative.  Therefore, it is crucial to assess the potential of district heating and to identify the target areas for in-depth investigations. This necessity demands easy and straightforward tools, which can provide a first order approximation of the construction cost of new networks.  One of these tools is the capital cost model developed by Persson & Werner, which is based on, among others, the effective width parameter. This is an indicator of the required trench length in an area supplied by district heating and has been related to the building density.  This work has contributed to the understanding of the effective width parameter in a wide range of building densities, taking advantage of one of the largest district heating networks in Denmark, and provided new equations that relate it to various indicators of building density.  Furthermore, the average pipe diameter of district heating pipes has been linked to another crucial parameter in district heating technology, the linear heat density, extending prior work conducted by Persson and Werner.  In addition, Persson and Werner's model and the newly found empirical expressions have been validated in various Danish district heating networks, showing that the model provides relatively accurate results on an aggregate level and large areas but dismally fails in low-extension areas.  Finally, the model has been applied to the European Union showing that district heating networks could potentially supply a third of the heat demand in 2050. / Lösningen av de pågående klimat- och energikriserna kräver en radikal omvandling av energisystemet, där hållbarhet, inga koldioxidutsläpp och energieffektivitet bör spela en avgörande roll. Denna revolution bör sträcka sig till alla delar av energisystemet, inklusive sektorn för uppvärmning och kylning av byggnader, som står för en tredjedel av Europas slutliga energibehov och på den europeiska kontinenten fortfarande till största delen försörjs av fossila bränslen. Fjärrvärme är en enkel men kraftfull teknik som kan bidra till denna utmaning. Som nätverksinfrastruktur kännetecknas den av flexibilitet i värmeproduktionen, vilket möjliggör inkorporering av ett brett utbud av värmekällor över tid. Dessutom möjliggör det återvinning av värme som annars skulle gå till spillo och användning av lokala värmekällor på ett mer kostnadseffektivt sätt. Dessutom kan dess koppling till elsektorn underlätta ökningen av intermittenta elektriska förnybara energikällor. Detta till trots täcker fjärrvärme för närvarande bara en tiondel av det europeiska behovet av uppvärmning och kylning av byggnader, om än med betydande skillnader mellan länderna. Utbyggnaden av nya fjärrvärmenät är dessutom kapitalkrävande och kan endast motiveras i de områden där koncentrationen av värmebehovet är tillräckligt hög för att ge en lägre kostnad för samhället än ett individuellt alternativ. Därför är det avgörande att bedöma potentialen för fjärrvärme och att identifiera målområdena för fördjupade utredningar. Denna nödvändighet kräver enkla och okomplicerade verktyg, som kan ge en första ordningens uppskattning av investeringskostnader för nya nätverk. Ett av dessa verktyg är kapitalkostnadsmodellen utvecklad av Persson & Werner, som bygger på bland annat parametern effektiv bredd. Detta är en indikator på den erforderliga dikeslängden i ett område som försörjs av fjärrvärme och har relaterats till byggnadstätheten. Detta arbete har bidragit till förståelsen av effektiv bredd-parametern i ett vitt spektrum av byggnadstätheter, vars studium drar fördel av ett av de största fjärrvärmenäten i Danmark, och har gett nya ekvationer som relaterar den till olika indikatorer på byggnadstäthet. Vidare har den genomsnittliga rördiametern för fjärrvärmerör kopplats till en annan avgörande parameter inom fjärrvärmetekniken, den linjära värmedensiteten, vilket utökar tidigare arbete utfört av Persson och Werner. Dessutom har Persson och Werners modell och de nyfunna empiriska uttrycken validerats i olika danska fjärrvärmenät, vilket visar att modellen ger relativt exakta resultat på aggregerad nivå och stora ytor men mindre så i lågutbyggnadsområden. Slutligen har modellen tillämpats på EU som visar att fjärrvärmenät potentiellt kan tillgodose en tredjedel av värmebehovet år 2050. / Quantification of synergies between Energy Efficiency first principle and renewable energy systems

The modern gas turbine engine industry needs a simpler and faster method to facilitate the design of gas turbine combustors due to the enormous costs of experimental test rigging and detailed computational fluid dynamics (CFD) simulations. Therefore, in the initial design phase, a couple of preliminary designs are conducted to establish initial values for combustor performance and geometric characteristics. In these preliminary designs, various one-dimensional models using analytical and empirical formulations may be used. One of the disadvantages of existing models is that they are typically geometric dependant, i.e. they apply only to the geometry they are derived for. Therefore the need for a more versatile design tool exists. In this work, which constitutes the first step in the development of such a versatile design tool, a single equation-set network simulation model to describe both steady state compressible and incompressible isothermal flow is developed. The continuity and momentum equations are solved through a hybrid type network model analogy which makes use of the SIMPLE pressure correction methodology. The code has the capability to efficiently compute flow through elements where the loss factor K is highly flow dependant and accurately describes variable area duct flow in the case of incompressible flow. The latter includes ducts with discontinuously varying flow sectional areas. Proper treatment of flow related non-linearities, such as flow friction, is facilitated in a natural manner in the proposed methodology. The proposed network method is implemented into a Windows based simulation package with a user interface. The ability of the proposed method to accurately model both compressible and incompressible flow is demonstrated through the analyses of a number of benchmark problems. It will be shown that the proposed methodology yields similar or improved results as compared to other’s work. The proposed method is applied to a research combustor to solve for isothermal flows and flow splits. The predicted flows were in relatively close agreement with measured data as well as detailed CFD analysis. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2005. / Mechanical and Aeronautical Engineering / unrestricted

Lärande med elektroniska medel har potentialen att revolutionera lärande. Via datorskärmen kan man enkelt åskådliggöra fysikaliska fenomen och underlätta arbetet för läraren. Om en utbildning bedrivs elektroniskt med hjälp av en dator och på distans uppstår en del svårigheter men samtidigt möjligheter, jämfört med en traditionell utbildning med fysisk närvaro i en skola. Datorer ger möjligheten att ta hänsyn till pedagogiska aspekter som kan effektivisera lärande. I dagens läge finns det inte ett utarbetat sätt att lära ut med elektroniska medel som garanterar ett gott lärande resultat. Hur en elektronisk kurs utformas är upp till läraren och institutionen som erbjuder kursen. I denna rapport ger vi ett enkelt förslag på hur vi anser en elektronisk kurs bör vara utformad samt det innehållet i kursen bör täcka. / Teaching by electronic means has the potential to revolutionize teaching. The screen of the computer can easily visualize physical phenomenon and facilitate the work of the teacher. If an education is conducted electronically and by distance it creates some difficulties but at the same time opportunities, compared to traditional education with a physical presence at a school. Today there is no prepared way to teach by electronic means that guarantees good teaching results. How an electronic course is formed is decided by the teacher and the institution offering the course. In this report we give a simple suggestion of how we consider an electronic technics course should be formed and what the course content should cover.

Fernkälte bietet das Potenzial, wirtschaftlich und ökologisch vorteilhaft zur Deckung des stetig zunehmenden Klimakältebedarfs beizutragen. Im Rahmen dieser Arbeit wurde ein dynamisches thermohydraulisches Netzmodell „ISENA“ entwickelt, mit dem während der Planung und des Betriebs von Fernkältesystemen auftretende Fragen, beispielsweise in Bezug auf Wirtschaftlichkeit und Energieeffizienz, beantwortet werden können. Das Netzmodell setzt sich aus einem quasistationären hydraulischen Modell und einem instationären thermischen Modell zusammen, das auf der Verfolgung von Wasserpfropfen durch das gesamte Netz basiert (Lagrange-Ansatz). Mit diesem Modellierungsansatz können numerische Fehler sowie Bilanzungenauigkeiten vermieden werden, sodass sich eine höhere Ergebnisgüte im Vergleich zu bisher bekannten Netzmodellen erreichen lässt. Ebenfalls neu entwickelt wurde das Teilmodell zur Abbildung der Wärmeströme über die Wände unterirdischer Rohrpaare (Kälteverluste und -gewinne). Dieses Modell erlaubt die Bestimmung der instationären Rohrwand-Wärmeströme für wärmegedämmte unterirdische Rohrpaare, Rohrpaare mit gedämmtem Vor- und ungedämmtem Rücklauf sowie ungedämmte Rohrpaare. Anhand von Validierungs- und Verifikationsrechnungen wird gezeigt, dass ISENA verlässliche Ergebnisse liefert und für die praktische Anwendung geeignet ist. Abschließende Beispielrechnungen geben einen Einblick in die Untersuchungsmöglichkeiten, die das neue Modell bietet – unter anderem im Hinblick auf den Vergleich von Pumpenregelungsvarianten, den Einfluss von Rohrdämmung und Erdreicheigenschaften auf Kälteverluste und -gewinne sowie die Einbindung von Hochtemperatur-Kälteverbrauchern in den Netzrücklauf. / District cooling can provide economic and ecological benefits while supplying the increasing cooling demand for air conditioning. In the present thesis, a dynamic thermo-hydraulic model “ISENA” is presented which may be used in order to answer questions arising during design and operation of district cooling networks—e. g., that are related to economic and energy efficiency. The network model consists of a quasi-static hydraulic module and a transient thermal module being based on the tracking of water segments through the entire network (Lagrangian method). With this approach, numerical errors and inaccuracies in the balance of conserved quantities could be avoided, which eventually leads to a better reliability of the results as compared to that obtained from other network models. Additionally, a new sub-model has been developed for predicting the transient heat flux through the walls of buried pipes in order to model thermal gains and losses. This model covers un-insulated, insulated and combinations of insulated as well as un-insulated pipes. Calculations performed for the purpose of validation and verification are presented in order to demonstrate that ISENA provides reliable results and hence is suitable for practical applications. Finally, example simulations show the various possibilities provided by the new model—for example, concerning the comparison of different strategies for pump control, the influence of pipe insulation and soil properties on thermal gains and losses as well as the connection of buildings equipped with high temperature cooling systems to the return line of the network.

Fernkälte bietet das Potenzial, wirtschaftlich und ökologisch vorteilhaft zur Deckung des stetig zunehmenden Klimakältebedarfs beizutragen. Im Rahmen dieser Arbeit wurde ein dynamisches thermohydraulisches Netzmodell „ISENA“ entwickelt, mit dem während der Planung und des Betriebs von Fernkältesystemen auftretende Fragen, beispielsweise in Bezug auf Wirtschaftlichkeit und Energieeffizienz, beantwortet werden können. Das Netzmodell setzt sich aus einem quasistationären hydraulischen Modell und einem instationären thermischen Modell zusammen, das auf der Verfolgung von Wasserpfropfen durch das gesamte Netz basiert (Lagrange-Ansatz). Mit diesem Modellierungsansatz können numerische Fehler sowie Bilanzungenauigkeiten vermieden werden, sodass sich eine höhere Ergebnisgüte im Vergleich zu bisher bekannten Netzmodellen erreichen lässt. Ebenfalls neu entwickelt wurde das Teilmodell zur Abbildung der Wärmeströme über die Wände unterirdischer Rohrpaare (Kälteverluste und -gewinne). Dieses Modell erlaubt die Bestimmung der instationären Rohrwand-Wärmeströme für wärmegedämmte unterirdische Rohrpaare, Rohrpaare mit gedämmtem Vor- und ungedämmtem Rücklauf sowie ungedämmte Rohrpaare. Anhand von Validierungs- und Verifikationsrechnungen wird gezeigt, dass ISENA verlässliche Ergebnisse liefert und für die praktische Anwendung geeignet ist. Abschließende Beispielrechnungen geben einen Einblick in die Untersuchungsmöglichkeiten, die das neue Modell bietet – unter anderem im Hinblick auf den Vergleich von Pumpenregelungsvarianten, den Einfluss von Rohrdämmung und Erdreicheigenschaften auf Kälteverluste und -gewinne sowie die Einbindung von Hochtemperatur-Kälteverbrauchern in den Netzrücklauf.:1 Einleitung 1.1 Situation 1.2 Aufbau und Betrieb von Fernkältesystemen 1.3 Netzmodellierung und -simulation 1.4 Präzisierte Aufgabenstellung 2 Stand der Wissenschaft und Technik 2.1 Begriffe und Definitionen 2.2 Rohrleitungen 2.2.1 Technik 2.2.2 Modellierung 2.3 Peripherie 2.3.1 Kälteabnehmer 2.3.2 Durchfluss- und Differenzdruckregler 2.3.3 Erzeuger 2.3.4 Pumpen 2.3.5 Bypass 2.4 Netz 2.4.1 Netzstruktur 2.4.2 Hydraulisches Verhalten 2.4.3 Thermisches Verhalten 2.4.4 Beispielsysteme 2.5 Zwischenfazit 3 Modellerstellung 3.1 Grundlagen 3.2 Rohrleitungen 3.2.1 Hydraulisches Rohrmodell 3.2.2 Modellierung des Rohrwand-Wärmestroms 3.2.3 Thermisches Rohrmodell 3.3 Peripherie 3.3.1 Kälteabnehmer 3.3.2 Durchfluss- und Differenzdruckregler 3.3.3 Erzeuger 3.3.4 Pumpen 3.3.5 Bypass 3.3.6 Rücklaufabnehmer 3.4 Netz 3.4.1 Hydraulisches Modell 3.4.2 Thermisches Modell 3.4.3 Gesamtmodell 3.5 Programmtechnische Umsetzung 4 Modellvalidierung und -verifikation 4.1 Vorbetrachtungen 4.2 Kernmechanismen 4.2.1 Hydraulik 4.2.2 Konvektiver Energietransport 4.2.3 Wärmeübertragung über die Rohrwand 4.2.4 Wärmezufuhr bei Kälteabnehmern 4.3 Schlussfolgerungen 5 Beispielsimulationen 5.1 Vorgaben 5.2 Referenzfall 5.3 Varianten 5.3.1 Pumpenregelung 5.3.2 Netz-Vorlauftemperatur 5.3.3 Rohrgeometrie und Erdreicheigenschaften 5.3.4 Rücklaufabnehmer 6 Zusammenfassung und Ausblick Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Anhang A Existierende Modelle A.1 Hydraulikberechnung mit Regelelementen A.2 Rohrwand-Wärmeströme A.3 Freie Konvektion bei Stillstand im Rohr B Numerisches Modell für Rohrwand-Wärmeströme B.1 Referenzmodell B.2 Bestimmung der Neipor-Parameter B.3 Tabellierte Neipor-Parameter C Modell ISENA C.1 Pfropfenteilung C.2 Programmtechnische Umsetzung C.3 Rohrklassen C.4 Stoffdaten / District cooling can provide economic and ecological benefits while supplying the increasing cooling demand for air conditioning. In the present thesis, a dynamic thermo-hydraulic model “ISENA” is presented which may be used in order to answer questions arising during design and operation of district cooling networks—e. g., that are related to economic and energy efficiency. The network model consists of a quasi-static hydraulic module and a transient thermal module being based on the tracking of water segments through the entire network (Lagrangian method). With this approach, numerical errors and inaccuracies in the balance of conserved quantities could be avoided, which eventually leads to a better reliability of the results as compared to that obtained from other network models. Additionally, a new sub-model has been developed for predicting the transient heat flux through the walls of buried pipes in order to model thermal gains and losses. This model covers un-insulated, insulated and combinations of insulated as well as un-insulated pipes. Calculations performed for the purpose of validation and verification are presented in order to demonstrate that ISENA provides reliable results and hence is suitable for practical applications. Finally, example simulations show the various possibilities provided by the new model—for example, concerning the comparison of different strategies for pump control, the influence of pipe insulation and soil properties on thermal gains and losses as well as the connection of buildings equipped with high temperature cooling systems to the return line of the network.:1 Einleitung 1.1 Situation 1.2 Aufbau und Betrieb von Fernkältesystemen 1.3 Netzmodellierung und -simulation 1.4 Präzisierte Aufgabenstellung 2 Stand der Wissenschaft und Technik 2.1 Begriffe und Definitionen 2.2 Rohrleitungen 2.2.1 Technik 2.2.2 Modellierung 2.3 Peripherie 2.3.1 Kälteabnehmer 2.3.2 Durchfluss- und Differenzdruckregler 2.3.3 Erzeuger 2.3.4 Pumpen 2.3.5 Bypass 2.4 Netz 2.4.1 Netzstruktur 2.4.2 Hydraulisches Verhalten 2.4.3 Thermisches Verhalten 2.4.4 Beispielsysteme 2.5 Zwischenfazit 3 Modellerstellung 3.1 Grundlagen 3.2 Rohrleitungen 3.2.1 Hydraulisches Rohrmodell 3.2.2 Modellierung des Rohrwand-Wärmestroms 3.2.3 Thermisches Rohrmodell 3.3 Peripherie 3.3.1 Kälteabnehmer 3.3.2 Durchfluss- und Differenzdruckregler 3.3.3 Erzeuger 3.3.4 Pumpen 3.3.5 Bypass 3.3.6 Rücklaufabnehmer 3.4 Netz 3.4.1 Hydraulisches Modell 3.4.2 Thermisches Modell 3.4.3 Gesamtmodell 3.5 Programmtechnische Umsetzung 4 Modellvalidierung und -verifikation 4.1 Vorbetrachtungen 4.2 Kernmechanismen 4.2.1 Hydraulik 4.2.2 Konvektiver Energietransport 4.2.3 Wärmeübertragung über die Rohrwand 4.2.4 Wärmezufuhr bei Kälteabnehmern 4.3 Schlussfolgerungen 5 Beispielsimulationen 5.1 Vorgaben 5.2 Referenzfall 5.3 Varianten 5.3.1 Pumpenregelung 5.3.2 Netz-Vorlauftemperatur 5.3.3 Rohrgeometrie und Erdreicheigenschaften 5.3.4 Rücklaufabnehmer 6 Zusammenfassung und Ausblick Literaturverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Anhang A Existierende Modelle A.1 Hydraulikberechnung mit Regelelementen A.2 Rohrwand-Wärmeströme A.3 Freie Konvektion bei Stillstand im Rohr B Numerisches Modell für Rohrwand-Wärmeströme B.1 Referenzmodell B.2 Bestimmung der Neipor-Parameter B.3 Tabellierte Neipor-Parameter C Modell ISENA C.1 Pfropfenteilung C.2 Programmtechnische Umsetzung C.3 Rohrklassen C.4 Stoffdaten

No description available.