Aurinkolämmitys

Tässä kandidaatintyössä käsitellään aurinkolämmitystä, sen hyödyntämiseen käytettävää tekniikkaa ja käytön laajuutta maailmanlaajuisesti. Työn tavoitteena on esitellä yleisimmät aurinkokeräintyypit ja niiden toimintaperiaatteet. Työssä selvitetään eri aurinkokeräinten asennettu kapasiteetti Suomessa ja muualla maailmalla. Lisäksi työssä on esitetty yleisimmät aurinkolämmön varastointitavat sekä kytkentäratkaisut Suomen oloissa. Työssä keskitytään käsittelemään ensisijaisesti nestekiertoisia aurinkokeräimiä niiden yleisyyden vuoksi, mutta myös ilmakiertoiset ja kattamattomat keräimet esitellään lyhyesti. Lisäksi pohditaan aurinkolämmityksen potentiaalia Suomessa ja maailmalla.

Competitive Solar Heating Systems for Residential Buildings (REBUS)

Research on solar combisystems for the Nordic and Baltic countries have been carriedout. The aim was to develop competitive solar combisystems which are attractive tobuyers and to educate experts in the solar heating field.The participants of the projects were the universities: Technical University of Denmark,Dalarna University, University of Oslo, Riga Technical University and Lund Institute ofTechnology, as well as the companies: Metro Therm A/S (Denmark), Velux A/S(Denmark), Solentek AB (Sweden), SolarNor (Norway) and SIA Grandeg (Latvia).The project included education, research, development and demonstration. Theactivities started in 2003 and were finished by the end of 2006. A number of Ph.D.studies in Denmark, Sweden and Latvia, and a post-doc. study in Norway were carriedout. Close cooperation between the researchers and the industry partners ensured thatthe results of the projects can be utilized. The industry partners will soon be able tobring the developed systems into the market.In Denmark and Norway the research and development focused on solarheating/natural gas systems, and in Sweden and Latvia the focus was on solarheating/pellet systems. Additionally, Lund Institute of Technology and University ofOslo studied solar collectors of various types being integrated into the building.

Elbesparing med pelletkaminer och solvärme i direktelvärmda småhus

The aim of this study was to investigate how electricallyheated houses can be converted to using wood pellet and solarheating. There are a large number of wood pellet stoves on themarket. Many stoves have a water jacket, which gives anopportunity to distribute the heat to domestic hot water and aradiator heating system. Three typical Swedish houses with electric resistanceheating have been studied. Fourteen different system conceptsusing wood pellet stoves and solar heating systems have beenevaluated. The systems and the houses have been simulated indetail using TRNSYS. The houses have been divided in up to 10different zones and heat transfer by air circulation throughdoorways and open doors have been simulated. The pellet stoveswere simulated using a recently developed TRNSYS component,which models the start- and stop phases, emissions and thedynamic behaviour of the stoves. The model also calculates theCO-emissions. Simulations were made with one stove without awater jacket and two stoves with different fractions of thegenerated heat distributed in the water circuit. Simulations show that the electricity savings using a pelletstove are greatly affected by the house plan, the systemchoice, if the internal doors are open or closed and thedesired level of comfort. Installing a stove with awater-jacket connected to a radiator system and a hot waterstorage has the advantage that heat can be transferred todomestic hot water and be distributed to other rooms. Suchsystems lead to greater electricity savings, especially inhouses having a traditional layout. It was found that not allrooms needed radiators and that it was more effective in mostcases t use a stove with a higher fraction of the heatdistributed by the water circuit. The economic investigation shows that installing a woodpellet stove without a water jacket gives the lowest totalenergy- and capital costs in the house with an open plan (fortoday's energy prices and the simulated comfort criteria). Inthe houses with a traditional layout a pellet stove givesslightly higher costs than the reference house having onlyelectrical resistance heating due to the fact that less heatingcan be replaced. The concepts including stoves with a waterjacket all give higher costs than the reference system, but theconcept closest to be economical is a system with a bufferstore, a stove with a high fraction of the heat distributed bythe water circuit, a new water radiator heating system and asolar collector. Losses from stoves can be divided into: flue gas lossesincluding leakage air flow when the stove is not in operation;losses during start and stop phases; and losses due to a highair factor. An increased efficiency of the stoves is importantboth from a private economical point of view, but also from theperspective that there can be a lack of bio fuel in the nearfuture also in Sweden. From this point of view it is alsoimportant to utilize as much solar heat as possible. Theutilization of solar heat is low in the simulated systems,depending on the lack of space for a large buffer store. The simulations have shown that the annual efficiency ismuch lower that the nominal efficiency at full power. Thesimulations have also shown that changing the control principlefor the stove can improve efficiency and reduce theCO-emissions. Today's most common control principle for stovesis the on/off control, which results in many starts and stopsand thereby high CO-emissions. A more advanced control varyingthe heating rate from maximum to minimum to keep a constantroom temperature reduces the number of starts and stops andthereby the emissions. Also the efficiency can be higher withsuch a control, and the room temperature will be kept at a moreconstant temperature providing a higher comfort.