Dissertationen zum Thema „Central heating system“

Enhancing the heat output of the hydronic central heating system in buildings can play a major role in reducing energy consumption and CO2 emission. The main aim of this PhD research is to investigate the effect of pulsed flow input on the energy consumption of panel radiators in hydronic central heating systems and the user indoor comfort defined by ASHRAE standard 55 and EN ISO 7730. The research covers thermal performance of panel radiator and the indoor comfort. The work was performed using dynamic control modelling, CFD and experimental testing to prove the concept. Results from the mathematical and CFD modelling of the hydronic radiator with pulsed flow using various frequencies and amplitudes showed that 20% to 27% of energy saving can be achieved compared to the constant flow while maintaining the same radiator target surface temperature of 50oC as recommended by the BS EN442. The indoor comfort results were also achieved as recommended by international standards including CO2 concentration at 1000PPM±50PPM, relative humidity at 50±9%, comfort temperature at 20±1.6oC, air velocity of below 0.15m/s and draught risk parameters of less than 15%. The numerical results agreed well with experimental results with maximum deviation of radiator temperature output of ±4.1%, indoor temperature ±2.83% and energy saving of ±1.7%. The energy saved due to the pulsed flow is attributed to the enhancement of the radiator heat transfer performance that leads to higher heat output at lower average mass flow rate of the hot water.

En jämförelsestudie har genomförts mellan två värmesystem. Analysen har genomförts med ett flerbostadshus som referensfasighet. Fastigheten är lokaliserad i Södertälje kommun. Analysen går ut på att bestämma vilket värmesystem som är fördelaktigt vid renovering av äldre flerbostadshus med avseende på energi och kostnad. De systemen som har behandlats är ett centralt värmesystem med motströmsvärmeväxlare och ett centralt värmesystem med frånluftsvärmepump. Det centrala värmesystemet (Eq aggregat) är ett centralt från- och tilluftssystem med återvinning (FTX system). Systemet använder en motströmsvärmeväxlare för överföring av värmeenergi mellan från- och tilluften. Det centrala värmesystemet (Energi well) är ett frånluftssystem (FX system) med en ny teknisk lösning. Systemet återvinner värme ur frånluften med hjälp av kondenserande frånluftsvärmpumpar. Värmepumparna finns i en frånluftskammare på vindsvåningen. Den återvunna värmen förs sedan vidare till undercentralen för att värma upp varmvattnet. Analysen har genomförts med hjälp av teoretiska energi- och kostnadsberäkningar, intervjuer och faktainsamlingar.  Energiberäkningarna har bestått av en energibalansberäkning för att få fram den köpta energiförbrukningen. Kostnadsberäkningar har bestått av en livscykelkostnads kalkyl och en kostnads beräkning per producerad värmeenergi. De resulterande värdena för båda värmesystemen har sedan jämförts med varandra. Resultatet visade att värmesystemet Energy well var mest fördelaktig ur både energi och kostnad perspektiv. Den årliga köpta energiförbrukningen var                          lägre än värmesystemet (Eq aggregat) med en motströmsvärmeväxlare. Driftkostnaden var  lägre än Eq aggregat, installations-kostnaderna var  lägre än Eq aggregat och slutlig var livscykelkostnaden  lägre än värme-systemet (Eq aggregat) med motströmsvärmeväxlare. Men underhållskostnaden var  högre än värmesystemet Eq aggregat. Slutsatserna för de teoretiska undersökningarna gav bättre värden för värmesystemet Energy well. Vilket innebär att Energy well är mest fördelaktig utifrån energi- och kostnads perspektiv. Däremot ger värmesystemet med motströmsvärmeväxlare en lägre risk att ett driftfel inträffar i verkligheten.
A comparing study between two different heating systems has been accomplished. The analysis has been conducted with an apartments building as a reference project. The building is located in the municipality of Södertälje. The goal of the analysis is to determine which of the heating system is beneficial for older apartment buildings in terms of energy and cost. The systems that have been treated are a central heating system with a counterflow heat exchanger and a central heating system with an exhaust air heat pump. The central heating system (Eq unit) is a central exhaust- and supply air system with heat recovery. The system uses a counterflow heat exchanger to transfer the heat energy between the exhaust- and supply air. The central heating system (Energy well) is the latest technical solution of a central exhaust air system. The system recovers heat from exhaust air by condensing exhaust air heat pumps. The heat pumps are in an exhaust air chamber and it´s placed on the attic floor. The recovered heat energy sends then to the mechanical room to heat up the water system. The analysis has been accomplished by using theoretical energy- and cost calculations, interviews and data collection. The energy calculations are based on an energy balance equation to determine the bought energy consumption. The cost calculation is based on a life cycle cost equation and a cost equation per produced heat energy. The results of both heating systems have been compared with each other. The results showed that the heating system Energy well was most beneficial in both energy and cost perspective. The annual consumption of bought energy was                          lower each year than the heating system (Eq unit) with a counterflow heat exchanger. The operating costs of the system were  lower than Eq unit, the installation costs were  lower than Eq unit and final was the life cycle cost  less than the heating system (Eq unit) with counterflow heat exchanger. But the service cost was  higher than the heating system Eq unit. The conclusion of the theoretical investigations gave better values ​​for the heating system Energy well. This means than Energy well is most beneficial from the energy and cost perspectives. Contrariwise has the heating system with counterflow heat exchanger a lower risk of an operational failure to occur in reality.

Proposed office and apartment building is situated in the north-west area of the city of Jihlava. Office and apartment building is designed as four-storey detached house, flat roof with a single casing. There are three shops and common area in the 1st floor. In the second floor there are situated 4 apartments consisting of two rooms and a house cellar in the centre of the house. The third floor is of the same pattern as the second one. In the fourth floor there are 4 apartments consisting either of one room or three rooms and a house cellar in the centre of the house as well. The total number of the apartments is 12. The house is made of building system VELOX.

This thesis processes heating of the apartment house in Rožnov pod Radhoštěm, Vsetín district. Revit program was used for the design of the heating. Some calculations were made in Revit too. Then the correctness of the calculations was checked. The Revit families were made in this thesis. These families support the calculations and design automation. Then these procedures were applied to the apartment house. It is five floors building with 1012 m2 of built area. Thesis solves design of heating and technical room equipment. The technical room is placed in first floor. Heat supply is solved as central heat supply system. The ventilation is mechanical, equal pressure. Thesis is in – cooperation with the house planner and the air – conditioning system design.

An emerging trend in the building services industry is the installation of passive deaerators on the flow line of domestic wet central heating systems. To date, no data and theoretical models predicting the two-phase flow characteristics in domestic wet central heating systems are available in the open literature. This gap in literature has prevented essential design improvements to passive deaerators thus impeding the efficiency enhancement of such devices. Hence, the current study is aimed at assisting designers of deaeration devices by providing fundamental data and model correlations with respect to the two-phase flow characteristics typical in a wet domestic central heating system. For this purpose an experimental research project was adopted and several studies were carried out, including; (1) a comprehensive review to understand the background of the phenomena, (2) the design and construction of an experimental test rig to conduct the necessary investigations into the phenomenon of two-phase flow in domestic wet central heating systems, (3) the development of a reliable image capture and analysis technique, (4) the completion of a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. This research has, for the first time, provided an in depth analysis into two-phase flow characteristics in wet domestic central heating systems through the use of a high speed camera and image analysis techniques. The two-phase phenomenon finds its origins in high dissolved gas concentrations present in the water flowing through the closed loop system, thus resulting in super saturation conditions at the primary heat exchange wall conditions. Bubble sizes at the boiler flow line were found to be dependent on the bulk fluid velocity, heat flux and pressure, with a measured mean diameter in the range of 0.13 mm to 0.39 mm. The Winterton (1972a) force balance model for bubble size prediction was in reasonable agreement with the experimental results. This model was further improved through the correlation of our data with the inclusion of dimensionless groups. Bubble nucleation rates have been calculated in the range of 0.3 to 4 bubbles / cm2 s with total system bubble production rates measured in the range of 784 to 6920 bubbles per second. Bubble nucleation rates have been calculated through the consideration of the heat exchanger surface under super saturation conditions. A correlation for the model by Hepworth et al. (2003) for nonclassical heterogeneous nucleation is proposed based on the experimental data gathered during the present study. Experimental results have shown dissolution rates for the bubble size ratio in the range of 0.4 to 12 % per second with system conditions. A modification of the model developed by Epstein and Plesset (1950) for stationary bubble dissolution is proposed with the inclusion of the Sherwood number to capture the effects of turbulent diffusion. The volumetric void fraction distribution in vertical pipes was found to be quasi-homogenous across the pipe section while being strongly dependent on gravitational and turbulence effects in horizontal pipe bubbly flow. A CFD simulation predicted the volumetric void fraction distribution with reasonable accuracy.

This thesis deals with design and implementation of wireless system for automated control and monitoring of central heating. Some of the existing solutions and their characteristics are briefly introduced at first. The attention in this thesis is subsequently given to the analysis of wireless technologies and power supply methods suitable for home automation. With regard to ascertained findings, the design and subsequent implementation of system modules using Raspberry Pi, the ARM Cortex-M0+ microcontroller and the ZigBee communication modules were performed. The firmware for created modules was designed and implemented. The designed system can be controlled and monitored using a mobile application for the Android platform, whose design is also described in this thesis.

Wet central heating systems account for a very large portion of energy consumption in the UK and recent figures indicate that its usage in households will be increasing even further. Under such circumstances, it is desirable to use these systems in the most efficient way possible. However, dissolved gases that penetrate into central heating systems are later released as bubbles due to local supersaturated conditions occurring on the primary heat exchanger wall of the boiler. This leads to a two-phase flow throughout the pipework, causing microbubbles to escape to the upper parts of the system and creating cold spots in the radiators, thus, reducing its efficiency. There is an increasing trend in building services to install devices that remove these unwanted gases. Therefore, investigation of two-phase structures throughout different pipe installations will facilitate companies in enhancing their deaerator designs. In this regard, extensive experimental and computational investigations of two-phase flow structures were conducted within this study. Two-phase flow structures were measured by a photographic technique and investigated in means of void fractions, bubble sizes, and velocities. Fluid velocities in the range of 0.5 to 1.1 m/s at typical wet central heating temperature (60 to 80 °C) and pressures (2.2 to 27 bar) were utilized. Results show that that bubble production increases as temperature, boiler heating load, and saturation ratio escalate. On the other hand, it reduces when the pressure and flow rate of the system gets higher. A clear relationship between bubble sizes and system parameters was non-existent, except for the system flow rate (where bubble diameters decrease as the flow rate increases). Moreover, bubbles were evenly distributed during vertical flow when compared to horizontal flow, where bubbles tend to flow at the upper parts of the pipe. Furthermore, it was shown that bubble distributions were highly affected by obstacles like the 90 degree bend, thermocouple or pressure sensors. In addition, it was observed that axial flow development of bubbly flow was a continuous process and void fraction at the upper part of the pipe increased as the flow travelled through horizontal pipeline. Regarding the bubble velocity measurements, it was concluded that, bubble velocity profiles show development along both vertical and horizontal flows and approach to profiles which can be expressed with the power-law. Moreover, coalescence of two bubbles during horizontal flow was captured, emphasizing that the effect of coalescences should not be neglected at low void fractions. It was also found that bubbly flow in central heating systems was in a coalescences dominant regime and maximum bubble diameter observed at most positions were higher than theoretically defined values. Moreover, bubble dissolution effect was not observed at any of the test rig conditions. The reasons were thought to be the variation saturation ratio and axial flow development of two-phase flow, which supress the effect of dissolution and favour coalescence phenomenon. Finally, after evaluating conclusions from the experimental results and computational study regarding the effect of the 90 degree bend on void fraction distributions, it was concluded that the employed physical model and solver settings in ANSYS Fluent 14.5, can be utilized to predict bubble distribution developments throughout the central heating systems’ pipework. Keywords: Central heating systems, two-phase flow, bubbly flow, bubble distributions, bubble sizes, bubble velocities, coalescence, image processing, experimental fluid easurements.

The import of the vegetable has prevailed in the long run over the own production. In connection with this reality and increasing demand for the food with higher quality the production greenhouse is more often built. The providing heat, cold and electricity for the year-round operation is related to the construction and working of these objects. The theoretical part of this theses describes possible ways how to cover energy consumption for the model greenhouse in Kožichovice, Třebíč region. The heat losses and the year-round heat consumption were stated for the selected model and compared with the exact values from Kožichovice. The following method of energy supply was selected based on the calculated energy consumption - the separate cogeneration unit, cooperation of several cogeneration units, a biogas station, a heat pump and central heating system. These methods of energy supply were subjected to technical and economical comparison.

Baigiamajame darbe projektuojamas Biurų centras „Royal“ dviejų aukštų su požemine automobilių stovėjimo aikštele, kurio bendras plotas – 1257,8 m2. Objekte planuojama vykdyti įvairias administracines paslaugas, tai būtų kalbų biuras, vairavimo mokykla, renginių organizavimo agentūra. Biurų centras projektuojamas iš fibo blokelių mūro apšiltinant jį putu polistirolu, perdangos plokštės, rygeliai ir gelžbetonio sijos bus atremiamos i sumontuotas 400x400 kolonas. Pastate bus dveji liftai, taip pat įrengti tualetai pritaikyti neįgaliesiams. Pastatas šildomas su dujiniu katilu. Projektuojamo pastato statybos sklypas yra Pramonės gatvėje Šiauliuose. Jo plotas - 1544 m2. Sklypas yra patogioje miesto dalyje, kur dideli žmonių srautai, šalia yra viešojo transporto sustojimo vieta.
In this final work is designed two-stores with underground parking for cars office center „Royal“ with an area of 1257,8 m2. The facility is planned to carry out a variety of administrative services, be it linguistic office, driving school, event marketing agency. Office center is designed with fibo blocks masonry with insulation of polystyrene, floor slabs, beams and reinforced concrete beams will be brought to 400x400 assembled columns. The building will be two lifts, as well as toilets adapted to people with disable. The building is heated with a gas boiler. Projected building plot is in Pramonės Street in Siauliai. Its area of - 1544 m2. The plot is conveniently located where are the large flow of people, close to public transport stopping place.

Water-filled heat stores present a convenient, relatively inexpensive means of optimising the use of diminishing gas stocks for the central-heating of buildings. The British Gas Corporation recently launched a series of central-heating units with storage, for use in the domestic sector, whose benefits include: - reduced boiler size, more efficient boiler operation, load-levelling at the hours of peak gas demand. This thesis is divided into three parts. Part I examines the inherent advantage of a with-storage, domestic, central-heating system over a conventional system, by means of two simple computer-simulation programs. A minimum efficiency advantage of about 5% is anticipated; the variation of this advantage with the values of certain key parameters has been assessed. Part II is an interim report of a full-scale field trial in the commercial sector; a large (3.3m3) store was fitted in the heating system of a London school, and its performance during the first weeks of its operation is presented here. Returning to the domestic sector, Part III presents a study of the use of two integral heat exchangers in the storage vessels of the above domestic units, whereby hot water can be drawn instantaneously. An attempt to optimise this domestic hot-water facility has been made.

The purpose of the new building is the construction of sports and relaxation center in Jihlava in the Vysocina. The building will serve as a sports and leisure center also contains the 1st floor squash courts, relaxation area with jacuzzi, sauna and massage. In the 2nd floor will be located with aerobic fitness, office manager, a children's playground and a bar with seating. The building consists of two floors and a basement. External walls are lined with masonry elements of Heluz Family tl. 300 mm 3 square inches with excellent thermal insulation properties, the internal load-bearing walls of thick STI Heluz system. 300mm. The building can escape three unprotected pathways into the open towards the northwest and south. The building is situated in a slightly sloping terrain. From the main road to get to the building access road to the 1st floor. The overall height of the first floor is 4.00 m, the second floor is 4m and also underground floor is 3.40 m The building consists of three wings in the longitudinal structural system. The building has three floors: a basement and two floors. The roof is flat, single-layer, above the squash courts is inclined with an inclination of 6 degrees. The ground plan is mass divided into 3 wings on 1st floor with main entrance and staircase connecting all the floors in the middle of disposition. Ground object is longitudinally divided into differently sized parts of the corridor, which on each side of the staircase joining the center of the building. Check the plot is solved its own parking with direct entrance from the road.

Denna uppsats tar sitt avstamp från en gammal rapport vid namn ”Samkörning mellan värmepumpar och fjärrvärme. – Bostadsrättsföreningen Bogården” från 2008. Denna rapport behandlar en undercentral vari det fanns risk för spridning av legionellabakterier. Rapporten från 2008 mynnade ut i åtgärdsförslag som togs i beaktande av Brf. Bogården och insatser genomfördes senare av SWECO i form av en nyprojektering av hela anläggningen. Följden av detta blev att undercentralen 2012 byggdes om helt och hållet och nya styr- och reglerflöden inrättades. I detta arbete presenteras en bred bild av energiläget i världen och i Sverige för att sedan rikta fokus ner till Gävle och undercentralen i Brf. Bogården. I denna studie så genomfördes flertalet observationstillfällen där noteringar gjordes för att se hur anläggningen och dess styr- och reglerflöden tedde sig. Bieffekten av besöken bestod av upptäckter som på ett eller annat sätt påverkade anläggningen i sin helhet. Det som upptäcktes var att undercentralen inte styr och regleras enligt projekteringen, retur- och framledningstemperaturer var för höga och att värmepumparnas drifttider absolut inte var enligt funktionsbeskrivningen. Dessa styr- och reglerfel gör så att Bogården måste köpa in mer fjärrvärme än vad som behövs vilket leder till mer kostnader än nödvändigt.
This paper takes its starting point from an old report named ”Samkörning mellan värmepumpar och fjärrvärme. – Bostadsrättsföreningen Bogården” from the year 2008. This report discusses a sub-station where there was a risk of proliferation of legionella bacteria. The 2008 report resulted in action proposals that were taken into account by tenant Bogården and thereafter efforts were implemented by SWECO in the form of a new projection of the entire sub-stationed facility. What happened next was that the sub- center was rebuilt completely in 2012 and a new management control settings were put into use. In this work, a broad picture of the energy situation in the world and in Sweden is presented, and after that the paper shifts focus on Gävle and the sub-center of tenant Bogården. In this study, many observation visits were made and during these notes were made to see how the plant and its control and regulatory flows occurred. The side effect of the visits consisted of discoveries that in one way or another affected the plant. What was discovered was that the sub-central did not control and regulate according to the design, the return and outflow temperatures in the radiator circuit were way too high and the heat pump operating hours were not at all according to the functional description that was provided to aid this report. These controls and regulate errors forces the tenant Bogården to buy more district heating than needed, which leads to more costs than necessary.

In this thesis, I was solved assessment of nuclear power plant Dukovany, conection to the hot water network to city Brno. For determine the size needful enforcement was necessary to establish the heat balance of needs of the city of Brno and the size of the heat supply options. After that it was possible to determine the dimensions of pipes and optimize his routes of due to the current state of land along the route of thermal power supply. Power supply parameters were chosen with regard to the possibilities of technology used for transmission of the media and the status quo for distribution of the city Brno. After pushing the power supply ahead of the city Brno into the pumping station Bosonohy, and second part of the solution was the connection to the backbone wiring SCZT heat to individual customers. The last point was elaborated design management system of heat from nuclear power plant and urban local based resources on current management of heat supply system using consumption diagrams SCZT.

The dissertation analyses a possibility to install a steam turbine for steam reduction in the heating plant with a combined cycle, Červený Mlýn. In the first part of this work the constituent parts of Červený Mlýn plant are briefly described. Basic information is included about two considered solutions to the steam turbine for steam reduction. Then the thermic diagram of the whole heating plant and the heat exchanger station itself is presented. On the basis of the given values of the heat required in the hydrothermal system, duration of the steam flow through both variants of the steam turbine for steam reduction is determined. The thermodynamic calculation of the steam turbine for steam reduction is aimed at determination of the power output and its comparison with the power outputs of the steam turbines for steam reduction considered. In the economical profitability calculation, basic economical quantities are given for both the solutions and the more suitable solution is recommended.

The master's thesis deals with new construction Salesian center, which contents a leisure center and Church of Mary Help of Christians. The building is designed as two separate units divided with dilatation cleft. One building is reinforced concrete frame fill with masonry POROTHERM Profi 40, the second object was built from POROTHERM Profi 40. The whole building has a basement, the basement is designed as a monolithic reinforced concrete construction. Basement is insulated with extruded polystyrene thickness of 150 mm, upper building is insulated EPS polystyrene 70 mm thick and 100 mm thick ETICS system. The roof on both buildings is flat, smaller building is covered with vegetation roof, concrete frame is covered with a flat roof with asphalt sheets. There are prepared the study, complete design documentation, technical expertise, heat, fire safety solution construction including fire management and technical drawings, basic acoustic calculations of structures, the reverberation time in the nave of the church. Drawings were prepared using AutoCAD 2009 and technical expertise using Heat 2011 and Area 2011.

The diploma thesis is elaboration of project documentation of the object Housing for seniors in Brno - Dolní Heršpice. The site is located un the area with the planned development of the city. The object is detached, three-story with a partial basement. The building is divided into five parts. The building is based on concrete foundation pads and strips. The structural construction is a combined column and wall system in technological design as monolithic concrete. The building is designed as a low energy building, with contact insulation (ETICS). The whole building is designed with forced air exchange. An extensive and intensive walkable flat roof is designed. The aim is to create small, barrier-free, community housing with affordable services and support, with a possible life expectancy. Services for the elderly with reduced self-sufficiency and with mild health and mental dysfunctions are considered. The building is equipped with space for accommodation with a capacity of 48 beds, space for eating with a separate kitchen, space for leisure and physical activities, space for basic health and social care and space for administrative and technical facilities. The construction is divided into several buildings, the subject of the thesis is primarily the solution SO.01 - Housing for seniors

This diploma thesis presents a project documentation for construction of a community centre with a restaurant. Its construction site is located on the outskirts of town Jaroměřice nad Rokytnou, Poděbradova street. The building is composed from three parts, which are connected to each other. The first part houses the restaurant with its facilities. This part is a single floor structure covered by a flat green roof. Its façade is formed by white boards composed into an asymmetrical pattern. The second part serves as a backstage area where all the necessary facilities are located. This second part of the building is as the first part a single floor structure covered by a flat green roof. Its façade is formed by façade timber boards. The main entrance is located in the middle part, which is the third part the building. It has two floors and it houses an auditorium, a bar and amenities. Its façade is formed by trapezial boards. The construction system is formed by load bearing walls and by prestressed concreted floor panels or in some parts by cast-in-place reinforced concrete slabs. The building has strip foundations. Its interior walls are built from sand-limestone bricks with acoustic properties. The perimeter walls are covered with ventilated façade with mineral wool thermal insulation. The heating of the community centre is powered by gas boiler connected to single-vent chimney with ventilation shaft.

This thesis deals with the design and elaboration process of a project documentation of a sports centre. The designed sports centre building is situated in the southern part of the town of Polička, in the area determined for sports and free time activities complexes and areas. It is a two-floor, non-cellar, flat-roof building. It is based on plain concrete strip foundations and reinforced concrete foundation footing. The bearing, peripheral and partition walls are designed from POROTHERM hollow clay blocks. Reinforced concrete columns are designated in open disposition areas. The ceiling construction is made from SPIROLL pre-stressed concrete floor slabs and point-supported reinforced concrete slabs. The peripheral walls of the first aboveground floor are insulated with external thermal insulation system with a protective gabion facade. The peripheral wall thermal insulation in a bowling restaurant and gym halls extension is designed from a ventilated facade with CEMBRIT METRO facade cladding panels. The building is functionally divided into two main parts with a shared entrance. The sports centre with gyms and other sports facilities form the first part. Three squash courts, a mini-football piste, a special room for spinning and alpinning, a room for group exercising and cloakrooms with sanitary facilities are designed within one part of the sports centre. A restaurant with a bowling area and a kitchen with storerooms and other facilities for employees form the second part. The designed complex is barrier-free. There is aimed to be a car park for fifty cars, four motorbikes and a bus in front of the building. Three parking places are for disabled people.