Flat-plate and evacuated tube collectors

1. Solar Collector
Arpan Deyasi
Dept of ECE, RCCIIT, Kolkata, India
Course: EI605D
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Why Required?
It absorbs the energy of solar radiation, coverts into
Heat, transfers to fluid flowing inside it
uses
As a domestic water heater reducing energy cost
A large no of collectors are made to form array
which is utilized to produce electric energy in solar
thermal power plant

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 for domestic purpose
Flat-plate collector
Evacuated tube collector
 Classification
Non-concentrating -- collector area equals
to absorber area
Concentrating -- collector area greater than
absorber area

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o Insulated metal box
with a plastic/glass
cover
o Dark-coloured
absorber Plate
o Heat transport
system including fluid
and Insulating
Material
Major components
Flat-plate collector

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Absorber plate: Flat plate made by highly conductive
materials, surface is covered by flat black material with high
absorbance
Flow passage: Normally a tube attached to absorber plate,
conduct the working fluid through the collector
Cover plate: Made by transparent materials (glass/plastic),
placed above the absorber plate, reduces radiative and
conductive heat losses
Components of Flat-plate Absorber

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Components of Flat-plate Absorber
Insulation: Generally heat-resistant fiberglass is used at
sides and back of collector to reduce heat loss
Enclosure: A box that contains all components and
protects them from hazardous environmental conditions

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Advantages of Flat-plate collector
• Easy to manufacture
• Low cost
• Collect both beam and diffuse radiation
• Permanently fixed
• Little maintenance
How to increase efficiency?
• Use fluid having higher thermal conductivity
than water
• Creates vacuum inside the collector box so
that air can conduct heat

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Applications of Flat-plate collector
 Domestic
1. Hot water
2. cooking
 Commercial
1. Car wash
2. Military laundry facility
3. Power generation
4. Water pumping

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Evacuated tube collector
Major components
Absorbance layer
Heat pipe
Heat pump
Heat exchanger
Display

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Components of Evacuated tube collector
Absorbance layer: made of unique coating, placed inside
glass tube, small tubes are connected to it to minimize
heat loss
Heat pipe: made of Cu/steel, transfer very quickly the
generated heat
Heat pump: transfer the solar heated fluid to header pipe,
takes back heat to storage tank

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Components of Evacuated tube collector
Heat exchanger: transfer heat to fluid through heat pipe
Display: displays temperature

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o More expensive
o More susceptible to breaking in
domestic use
o Cannot be mounted horizontally,
must have a slope of 25°C
Advantages of Evacuated tube collector
o Achieves higher efficiency with large
temperature gradient between absorber
and surroundings
o Supports space heating
o Low weight system
Disadvantages of Evacuated tube collector

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Applications of Evacuated tube collector
1. Heat assisting device in heat engines
2. Solar cooker
3. Air conditioning
4. Swimming pool heating
5. Steam generation
6. Solar drying for industrial sectors

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https://energyeducation.ca/encyclopedia/Solar_collector
References
Er. R K Rajput, Non-Conventional Energy Sources and Utilisation
(Energy Engineering), S. Chand Publishing
B.H Khan, Non Conventioanl Energy Resources, Tata McGraw-Hill
Education