Solar energy in asia, in Kobe, Japan, september 1989 : Reports from ISES solar world congress and from study visits in India and Pakistan

The ISES Solar World Congress Clean and Safe Energy Forever was held in Kobe, Japan, September 4-8, 1989. Short impressions from the conference and the simultaneous exhibition are given. On our (separate) ways to Kobe, Eriksson visited institutions in the Bombay, India area, and Broman one institution in Islamabad, Pakistan. Accounts of these visits are given. Three papers presented in Kobe are included in an Appendix.

Solar energy studies and extramural learning

Extramural learning refers to the educational process that takes place outside the walls of the school (or the university). Extramural learning that takes place in a science center is characterized by hands-on and interactivity. Interactive solar energy exhibits are particularly well suited for out-door science centers. The paper presents some solar energy hands-on exhibits and extramural activities that the author has initiated and participated in.

Villasystem för solvärme

Del 1:Innehållsförteckning och korta sammanfattningarDEL 2:Verksamhetsberättelsen för perioden maj 1992 till april 1993 beskriver de arbeten som har gjorts av villasolvärmegruppen på SERC efter den inledande studie (SERC/UCFB-91/0039), där villasolvärmesystem kartlades. Följande arbeten beskrivs:- Utveckling av lågflödessystem och internationella kontakter- Uppbyggnad av värmelaboratorium på SERC- Praktiska test av värmelagringsenheten- Praktiska test av nya systemkomponenter i solvärmekretsen- Datasimulering inkluderande nyutvecklade systemkomponenterI verksamhetsplanen beskrivs huvudmålet för de arbeten som ska utföras under trårsperioden 93 - 96. Mera detaljerat beskrivs de arbeten som ska utföras under budgetåret 1993/94:- Beräkningsprogram för nogrannare dimensionering av finrörsvärmeväxlare- Konstruktion av maskiner för värmeväxlartillverkning- Utveckling av värmeväxlare för tappvarmvatten- Simuleringsberäkningar för hela systemet med PRESIM/TRNSYS.DEL 3:Del 3 innehåller en redovisning av mätresultat för den undersökta kombitanken. Temperaturförloppen på olika höjd i tankens har studerats vid uppvärmning genom solvärmeväxlaren och nedkylning genom tappning av varmvatten. Resultaten diskuteras kvalitativt och redovisas kvantitativt i form av diagram. Mätresultaten på två prototyper av den på SERC utvecklade finrörsvärmeväxlaren redovisas och diskuteras i jämförelse till traditionell värmeväxlare. De erhållna mätresultaten används som ingångsvärden för simuleringsberäkningar med PRESIM/TRNSYS. Problemen med de i PRESIM/TRNSYS befintliga modellerna diskuteras. De utförda modellberäkningarna tillåter en uppskattning av möjliga förbättringar i form av höjd årsverkningsgrad för ett svenskt villasolvärmesystem med kombitank. I del 3 redovisas dessutom de mätningar som har utförts på otika pumpar vilka skulle kunna användas i solfångarkretsen. Sex olika pumpar analyseras och diskuteras. Del 3 har följande rubriker:- Beskrivning av den undersökta lagringstanken- Mätningar på tappvarmvattenväxlare- Mätningar på solvärmeväxlare (kamflänsrör och finrörsvärmeväxlare)- Simuleringsberäkningar- PumpmätningarDEL 4:Del 4 innehåller publicerade rapporter under 1992 och 93 samt patentansökan för SERC?s finrörsvärmeväxlare: - NORTH SUN 1992, Solar Energy at High Latitudes, June 24-26 1992 Trondheim, Norway. Domestic solar heating system - a systematic study i progress Patentansökan på finrorsvärmeväxlare till Patent- och Registreringsverket från 93 01 23. ISES SOLAR WORLD CONGRESS, 23-27 augusti 1993, Budapest, HUNGARY Criteria for cost efficient small scale solar hot water installations.DEL 5:Del 5 hänvisar till rapporterna från IEA Task-1 4 mötena om solfångarsystem i- Hameln, Tyskland, augusti 1992 och- Rom, Italien, januari 1993.I rapporterna beskrivs aktiviteten inom den internationella arbetsgruppen speciellt med hänsyn på utveckling av villasolvärmesystem. I Rom presenterades principlösningen för den på SERC utvecklade finrörsvärmeväxlare. De har publicerats separat som nr 42 och 46 i SERCs rapportserie.

Evaluation of a high temperature solar thermal seasonal borehole storage

A solar thermal system with seasonal borehole storage for heating of a residential area in Anneberg, Sweden, approximately 10 km north of Stockholm, has been in operation since late 2002. Originally, the project was part of the EU THERMIE project “Large-scale Solar Heating Systems for Housing Developments” (REB/0061/97) and was the first solar heating plant in Europe with borehole storage in rock not utilizing a heat pump. Earlier evaluations of the system show lower performance than the preliminary simulation study, with residents complaining of a high use of electricity for domestic hot water (DHW) preparation and auxiliary heating. One explanation mentioned in the earlier evaluations is that the borehole storage had not yet reached “steady state” temperatures at the time of evaluation. Many years have passed since then and this paper presents results from a new evaluation. The main aim of this work is to evaluate the current performance of the system based on several key figures, as well as on system function based on available measurement data. The analysis show that though the borehole storage now has reached a quasi-steady state and operates as intended, the auxiliary electricity consumption is much higher than the original design values largely due to high losses in the distribution network, higher heat loads as well as lower solar gains.

Student and teacher response system : development of an interactive anonymous real-timeformative feedback system

This paper is focusing IT-supported real-time formative feedback in a classroom context. The development of a Student and Teacher Response System (STRS) is described. Since there are a number of obstacles for effective interaction in large classes IT can be used to support the teachers aim to find out if students understand the lecture and accordingly adjust the content and design of the lecture. The system can be used for formative assessment before, during, and after a lecture. It is also possible for students to initiate interaction during lectures by posing questions anonymously. The main contributions of the paper are a) the description of the interactive real-time system and b) the development process behind it.

Monitoring results of combined pellet and solar heating system

In this study the monitoring results of prototype installation of a recently developed solar combisystem have been evaluated. The system, that uses a water jacketed pellet stove as auxiliary heater, was installed in a single family house in Borlänge/Sweden. In order to allow an evaluation under realistic conditions the system has been monitored for a time period of one year. From the measurements of the system it could be seen that it is important that the pellet stove has a sufficient buffer store volume to minimize cycling. The measurements showed also that the stove gives a lower share of the produced heat to the water loop than measured under stationary conditions. The solar system works as expected and covers the heat demand during the summer and a part of the heat demand during spring and autumn. Potential for optimization exists for the parasitic electricity demand. The system consumes 680 kWh per year for pumps, valves and controllers which is more than 4% of the total primary heating energy demand.

Annual CO-emissions of combined pellet and solar heating systems

Emissions are an important aspect of a pellet heating system. High carbon monoxide emissions are often caused by unnecessary cycling of the burner when the burner is operated below the lowest combustion power. Combining pellet heating systems with a solar heating system can significantly reduce cycling of the pellet heater and avoid the inefficient summer operation of the pellet heater. The aim of this paper was to study CO-emissions of the different types of systems and to compare the yearly CO-emissions obtained from simulations with the yearly CO-emissions calculated based on the values that are obtained by the standard test methods. The results showed that the yearly CO-emissions obtained from the simulations are significant higher than the yearly CO-emissions calculated based on the standard test methods. It is also shown that for the studied systems the average emissions under these realistic annual conditions were greater than the limit values of two Eco-labels. Furthermore it could be seen that is possible to almost halve the CO-emission if the pellet heater is combined with a solar heating system.

Thermal losses in sealed, gas-filled flat plate solar collectors

A sealed space between absorber and cover glass makes it possible reducing the influence of humidity condensate and dust at the same time as the enclosed space can be filled with a suitable gas for lowering the losses. This paper is about the size of the losses in these collectors. A calculating model of a gas-filled flat plate solar collector was built in Matlab with standard heat transfer formulas. It showed that the total loss can be reduced up to 20% when changing to an inert gas. It is also possible using a much shorter distance and still achieve low losses at the same time as the mechanical stresses in the material is reduce.