Progress Report

1. Progress Report

2. Summary of Last Meeting • It was suggested that I should write up all my PCM and solar notes whilst they were still relatively fresh. • The observation was made that I was trying to do to much and that I should look back at my aim and objectives. It was proposed that I should fix certain variables to keep the project manageable.

3. Write Up of Notes • In answer to the first point I have written up all my notes concerning PCM and solar energy.

4. Variables To Be Considered • PCM • Containerisation • Collector choice • System layout • Data to be collected

5. PCM • A comprehensive list of desired PCM properties was made and used as the basis for selection these included: • Compatibility with plastic • High heat of fusion • High thermal conductivity • High density and specific heat capacity • Thermal stability • Low melting point • Non flammable, non toxic and non corrosive • Low containment costs

6. PCM Continued • Sodium sulphate hexahydrate (SSH) was selected as the PCM to be used in the study for several reasons: • It possessed more of the desired properties than its rivals • It is compatible with plastic • It is non flammable • It is not reliant on petroleum refinement

7. PCM Continued • However, SSH is not without its problems namely supercooling and phase segregation • To address these problems it is proposed to purchase a SSH which contains a nucleator and a thickener

8. Containerisation • A list of desired properties for containerisation was compiled to aid the selection process these included: • Plastic degradation • Strength and flexibility • Temperature resistance • Fire resistance

9. Containerisation Cont’d • High density polyethylene or polypropylene Tupperware was selected as a container for the following reasons: • They possess many of the listed properties • Both are compatible with inorganic PCMs • Both have operating temperatures exceeding that required for the study • Tupperware is flexible, air tight and heat resistant • No costly moulds required or lengthy construction procedure needed • Long and thin shape increases surface area

10. Containerisation Cont’d • A panel system was selected for the following reasons: • Easy to install and remove from the building • Can be fitted above or below floor system • The system operates on a similar principle to underfloor heating • Possibility of using multiple PCMs with different melting points which can improve system efficiencies by 13-26% and heat outputs by 64%-138%

11. Collector Choice • Flat plate collectors were selected over evacuated tube collectors (ETC) for several reasons: • Simple construction reduces cost • Some ETC use two heat exchangers • Flat plate collectors with a selective coating have out performed ETC under identical conditions in two separate independent tests

12. System Type • Four possible system types are available: • Thermo siphon • Draindown • Drainback • Closed loop

13. Thermosiphon

14. System Type Continued • A thermosiphon system was not selected for the following reasons: • They have no freeze protection • They can clog up if used with hard water • They can suffer with reverse thermosiphoning if no check valve installed

15. Draindown System

16. System Type Continued • A draindown system was not selected for the following reasons: • An electronic valve is used to prevent freezing • Water needs to be conditioned to prevent corrosion and scale build up • Heated water is wasted when the system drains

17. Drainback System

18. System Type Cont’d • A drainback system was not selected for the following reasons: • It cannot be used in hard water areas • High energy consumption as large pumps are needed to overcome height differences between drainback tank and collector • Careful design required to ensure that no water trapped when collectors drain

19. System Type Cont’d • A closed loop system was selected for the following reasons: • Positive freeze protection • Longer system life • No motorized valves or breaker valves to fail • Circulation pumps can be small as they only have to overcome friction in pipework • Health

20. System Schematic

21. Solar Data Four sources exist to obtain solar data: • Use figures for solar irradiation quoted by CIBSE and assume solar fraction of the system • Use solar irradiation figures gathered by Brighton & Hove council (BHC) and again assume solar fraction of system • Use data gathered by (BHC) for solar water heaters fitted to some of their properties • Install a solar hot water heating system at the University

22. Solar Data Continued • Where solar and system data gathered often insufficient parameters measured to be of value. The following parameters should be measured: • Energy delivered from collector to storage tank • Energy consumed by load • Energy delivered by auxiliary heater • Irradiation in the collector plane • Flow rate through the collector loop • Ambient temperature

23. Solar Data Continued • Incoming cold water temperature • Storage cylinder temperature • Solar panel temperature • Energy consumed by solar system • It is also important to know the collector area and storage tank volume

24. PCM Panels • The following parameters need to be measured : • Flow rate • Inlet and outlet temperature at every panel intersection • Temperature within the PCM • Floor covering temperature • Air temperature • Infiltration rate and air speed

25. Test Box • In order to measure some of the aforementioned parameters a test box is needed. This must fulfil the following criteria: • It must be representative of the construction used in any modelling to aid comparison • It must be able to accommodate a series of panels • It must be easy to fit and remove panels • It must be possible to alter the type of floor used

26. Dolls House Test Box

27. Future Work • Finalise experimental methodology • Make a final list of equipment needed • Cost equipment needed • Model system • Start panel and test box construction

28. The End