Transcript No Slide Title

Progress Report
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.
Write Up of Notes
 In answer to the first point I have written up
all my notes concerning PCM and solar
energy.
Variables To Be Considered
 PCM
 Containerisation
 Collector choice
 System layout
 Data to be collected
PCM
 A comprehensive list of desired PCM properties
was made and used as the basis for selection these
included:
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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
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
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
Containerisation
 A list of desired properties for
containerisation was compiled to aid the
selection process these included:
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Plastic degradation
Strength and flexibility
Temperature resistance
Fire resistance
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
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%
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
System Type
 Four possible system types are available:
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Thermo siphon
Draindown
Drainback
Closed loop
Thermosiphon
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
Draindown System
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
Drainback System
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
System Type Cont’d
 A closed loop system was selected for the
following reasons:
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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
System Schematic
Air Vent
Sensor
Cold Water Tank
Collector
Differential
Temperature
Controller
Tempering Valve
Hot Water Taps
Mixing Valve
Drain Points
Sensor
Pump
Wood Stove With
Coil or Gas Fired
Condensing Boiler
Super Insulated
Twin Coil
Stainless Steel
Tank
PCM Filled Panels
Solar Data
Four sources exist to obtain solar data:
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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
Solar Data Continued
 Where solar and system data gathered often
insufficient parameters measured to be of value.
The following parameters should be measured:
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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
Solar Data Continued
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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
PCM Panels
 The following parameters need to be measured :
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Flow rate
Inlet and outlet temperature at every panel intersection
Temperature within the PCM
Floor covering temperature
Air temperature
Infiltration rate and air speed
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
Dolls House Test Box
MDF roof
Thermal Insulation
Lightweight Block
Cavity Wall
Floorboards
Floor Joist
Glazing
PCM Panels
Timber Batten
Future Work
 Finalise experimental methodology
 Make a final list of equipment needed
 Cost equipment needed
 Model system
 Start panel and test box construction
The End