Progress Report

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Progress Report
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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.
  

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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 Contd

• 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

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Containerisation Contd

• 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

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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

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Thermosiphon
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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

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Draindown System
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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

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Drainback System
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System Type Contd

• 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

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System Type Contd

• 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

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System Schematic
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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

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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

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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

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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

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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

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Dolls House Test Box
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Future Work

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

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The End