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227 Uppsatser om Thermal cracks - Sida 2 av 16

Datormodellering av en värmelagrande betongväggs inverkan på det termiska klimatet i ett växthus

This report describes the building of a computer model that makes it possible to simulate the thermal climate in a greenhouse. The computer model is built on the physical theory of heat exchange that occur in a greenhouse, such as radiation and convective heat exchange. The model also includes the heat storage that is active in a greenhouse.The computer model is used to simulate the thermal climate in a greenhouse under three periods, winter, spring and summer. It also investigates which effect a concrete wall has on the thermal climate in a greenhouse. The purpose of putting a concrete wall in the greenhouse model is to investigate the possibility to store heat during the day and then use this heat when the temperature drops during the night.The result from the simulations shows that a concrete wall levels the big difference in temperature that normally occurs under a day in a greenhouse.

Isolerande balkonginfästningar : Thermally-insulated balconies

In this work a study has been performed to show the different kinds of insulated balcony connections exists on the market. In the work there is also a short description of thermal bridges concerning balconies. A description of older solutions for balcony connections is given as well as a calculation of the difference in energy costs for a insulated balcony connection compared to the standard connection. The work includes a short description of the different products. After that there is a short information about their insulation properties, durability, acoustic performance, assembly, computer programme and a short analyses for each product..

Temperaturzoner för lagring av värmeenergi i cirkulärt borrhålsfält

The thermal response of a borehole field is often described by non?dimensional response factors called gfunctions.The g?function was firstly generated as a numerical solution based on SBM (Superposition BoreholeModel). An analytical approach, the FLS (Finite Line Source), is also accepted for generating the g?function. In thiswork the potential to numerically produce g?functions is studied for circular borehole fields using the commercialsoftware COMSOL.

Inverkan av stora mängder halm som underlag i grisningsboxen på den nyfödda smågrisens temperaturreglering :

The aim of the present study was to evaluate the effects of large amounts of straw in the farrowing pen on thermal regulation of the newborn piglet in different weight classes. 20 sows were given 15 kg of straw in the farrowing pen 2 days prior to until 7 days after parturition. A control group of 18 sows had no straw in the pen. 6 litters from each treatment were observed. Measurements of piglet body temperature were made at 0h, 2h, 4h, 8h and 24h after parturition. At ?8h? the body temperature of the piglets in the Straw group were significantly higher (P=0,0149) than the piglets in the Control group.

Termomekanisk utmattning av Sanicro 25 : Materialmodellering med finita elementmetoden

The report aims to describe the austenitic stainless steel Sanicro 25 from a thermomechanical point of view. The thermal and mechanical properties of the material make it suitable for use in coal ? and thermal power plants. By the use of Sanicro 25 it would be possible to bring the efficiency of these plants up while bringing the carbon emissions down.A material model is created from material testing and validated through simulation in the finite element software Abaqus. The model that has been derived describes the material behavior during loading and stress relaxation for the first cycle in a thermomechanical fatigue test well.

Påverkan på energianvändning och termisk komfort vid reglerinstabilitet

The purpose of the study is to investigate the possible effects of an unstable ventilation system and its influence on energy use and thermal comfort. The report also explores how qualified personal working with HVAC view and handles system control.In order to meet the requirements in energy efficiency and a comfortable indoor climate control regulation is a prerequisite. With optimized increased complexity of the climate systems, it becomes more challenging to control the system and the risk of unstable control increases. No previous studies about what affect an unstable system can have on energy use and thermal comfort have been found.The report is based on several tests were the controlling variable has been increased until the system becomes unstable. Two different types of unstable systems have been investigated.

Värmeöverföring i bergvärmesystem : En numerisk analys av den ringformade koaxiala borrhålsvärmeväxlaren

The borehole heat exchangers of today suffer from poor thermal and hydrodynamic performance. The purpose of this thesis is to improve the performance of ground source heat pump systems and thermal energy storages by increasing the energy efficiency of the borehole heat exchangers. For this reason, the annular coaxial borehole heat exchanger (CBHE) has been analyzed. This type of heat exchanger is interesting in terms of both thermal and hydrodynamic performance. A model has been set up in the program Comsol Multiphysics in order to investigate the heat transfer characteristics along the borehole.

Temperatursprickskatalogen : Hjälpmedel vid beräkning av temperatursprickor i vanligt förekommande  betongkonstruktioner.

Rapporten innehåller inledningsvis en faktadel med allmän information kring temperatursprickor i betong. Här presenteras bl a uppkomsten av fenomenet, vilka typer av sprickor som förekommer och vad ett tvång är. Tanken är att ge läsaren tillräcklig kunskap för att kunna förstå sig på de övriga delarna i rapporten.Resultatet och det huvudsakliga arbetet redovisas i form av tabeller med tillhörande illustrationer där det går att utläsa vilken sprickrisk som förekommer vid flera specifika fall och vilken åtgärd som bör vidtas för att eliminera sprickrisken. Som konstruktör kan du med din egen indata, dvs. dimensioner och temperaturer, följa tabellen och finna resultatet för ditt specifika fall.

Vibrationsproblem i närliggande konstruktioner i samband med markarbete

Ground work like blasting, piling and excavation has always had a great influence during the planning phase of a construction project since it can cause damages on adjacent buildings and have severe economic consequences. This thesis deals with how vibrations caused by ground work influence near-by buildings and what methods geotechnicians and construction entrepreneurs use to handle these risks.The purpose of this thesis is to explain risk management in relation to ground work. In order to achieve this I have used a qualitative method by interviewing a geotechnician and a ground work contractor who possess knowledge and experience useful to this thesis. The result shows that vibrations from ground work spread through the ground as seismic waves that cause displacements and packing in the ground visible in adjacent buildings as cracks and subsidence damages. Geotechnicians study ground work vibrations by means of ground investigations and experience from previous projects in order to produce a risk analysis that entrepreneurs can use to reduce damages.

Värmeförluster vid utvändigt placerade ventilationssystem

To be able to handle tomorrows need for limited energy consumption we need to reduce our use of energy. The building sector stands for around 40 % of all energy consumption in the society. The government has put up a goal to reduce the energy consumption in our buildings with 20 % by year 2020 and 50 % by year 2050 compared with year 1995. To be able to do reach that goal we need a more energy efficient building stock.The main part of the energy used in our buildings is used for space heating. By installing ventilation systems with heat recovery on the exhaust air it is possible to use the heat-energy in the exhaust air to warm up the incoming air.

Köldbryggor och energiförluster. En studie om energiförluster genom balkonginfästningar och deras betydelse för byggnadens totala energibehov

In this report the balconies? abutments for a property in Bo01-area in Malmö has been studied. The property which is called Vitruvius contains four build-ings where two of them have corbelling balconies with intermittent abutments. With intermittent abutment means that the 50 mm thermal bridge insulation that the balconies is equipped with, is broken regularly by a 300 mm concrete heel. The reinforcement bar that holds the balcony runs through this heel.

TILLFÄLLIGA EFFEKTTOPPAR I FJÄRRVÄRMEN : Kan man med hjälp av lagrad värme undvika att de uppstår i betonghus?

Climate and environmental issues is now high on the agenda. We live in a generation that must try to solve some major environmental problems. Buildings and habitations account for approximately 40 % of Sweden's total energy today. To reduce this figure, as needed, more research in the field of energy efficiency is required.This thesis concerns the heating of buildings. The load on district heating is heavy during certain times of the day.

MOLNU : Att utveckla ett gemensamt gränssnitt

Climate and environmental issues is now high on the agenda. We live in a generation that must try to solve some major environmental problems. Buildings and habitations account for approximately 40 % of Sweden's total energy today. To reduce this figure, as needed, more research in the field of energy efficiency is required.This thesis concerns the heating of buildings. The load on district heating is heavy during certain times of the day.

Metoder för lastprioritering i fjärrvärmecentraler

A problem in the field of district heating is the oil burners needed to provide power when a peak load occurs. One possible way of reducing the needed amount of oil is to reduce the power demand for space heating in the district-heating substations when the need for district heating water exceeds a certain limit. This can be done by use of a locally working controller function.In this Thesis the options concerning load priority are evaluated. To evaluate the potential for using controller functions concerning peak load priority an experiment was brought out in a chosen district-heating substation. The impact on the indoor thermal comfort during a heat reduction was also taken into account.

Beräkning av värmeenergiförluster i flerbostadshus genom analys av den totala fjärrvärmeenergianvändningen :

This thesis has been carried out on behalf of IV Produkt AB and intends to set an average ratio of thermal energy losses in apartment buildings that were built during the 1960-1990. This shall be derived by analyzing the total district energy consumption that has been divided into three parts: heat energy losses (the actual heating requirements), the heating of domestic hot water and heating energy consumption for the controlled ventilation.Three different residential areas that were built during the years 1962-1966 and one that was built in 1993 has been analyzed. All residential areas are located in Växjö urban and contains between four and six apartment buildings.The analyzed objects have a mechanical exhaust ventilation systems and district heating as the heating method. No own laboratory work or experiments have been done in this thesis, the calculations have been done on the basis of parameters from VEAB, interviews with property managers, and literature studies. By calculations, we have got a result that is reported in Chapter 6.

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