Low Temparature Solar
Thermal Technology
Supervisor: Professor Herbert kabza
Prepared By: A.S.M. Abdul Hye
Energy Science ...
Energy-Resources word-wide

Energy Cubes: the Annual Solar
Irradiation Exceeds Several Times
the Total Global Energy Deman...
What is Solar Thermal?


Uses sun energy for thermal energy

Courtesy: xolar group
Thermal use of solar energy
Low Temperature Solar collectors



Flat plate collectors
Evacuated tube collector
Flat plate collectors

Courtesy: estif
Processes in a Flat-plate Collector
Glazed Flat Plate
Unglazed Flat plate collectors
Flat plate collectors


Pros are:
- cheaper to purchase.
-Non.tracking option
-Diffuse solar radiation utilization



Co...
Evacuted-tube Collectors
Heat pipe evacuated tube array

Source: reuk.co.uk
Evacuated U-tube array

Source: reuk.co.uk
Evacuted-tube Collectors
Pros are:
-Very low heat loss.
-Eliminate convective loss.
-High efficiencies at high temperature...
Energy Conversion in the Solar
Collector and Possible Losses

Source: Wagner and Co, 1995
Energy Conversion in the Solar
Collector and Possible Losses
The sum of The reflectance ρ, absorptance α and
transmittance...
How much energy does a solar
collector provide?
Graph of
efficiency and
temperature
ranges of various
types of collectors
...
Conversion Factor
Flat plate vs Evacuted tube

Optional
Flat plate vs Evacuted tube
Optional

source:
wikipedia
energy output (kW.h/day) of a flat plate
collector (blue lines; ab...
Efficiency Comparison between
collectors
Thermal Storage



Short-term storage systems.
Long-term storage systems.

Large storage systems can be:
• artificial st...
Different Types Of Heat Storage
There are different types of heat storage such as:
• Storage of sensible (noticeable) heat...
Sytem layouts



Open loop
Closed loop
Open Loop Systems

Courtesy: Design handbook by
MPMSAA
Closed loop Systems

Courtesy: design handbook by
MPMSAA
Heat transfer medium Selections
Water
>Nontoxic and inexpensive .
>With a high specific heat, and a very low
viscosity, it...
Heat transfer medium Selections
Non-toxic propylene glycol(in frost condition)
> Most common fluid used in closed solar wa...
Heat transfer medium Selections
Air
>Will not freeze or boil.
>Non-corrosive.
>Dis Advanteges:
>very low heat capacity.
>T...
Technology aspects



Systems for domestic hot water
Systems for space heating
Thermosiphon (or: natural flow)
systems
Forced circulation systems
Solar combisystem
• deliver solar energy to heat store (s)
with as low heat loss as possible;
• distribute all the heat ne...
Freezing
Few common strategies to prevent damage from
freezing:
>Polypropylene glycol
>Drain down
>Pump circulation
>Insul...
HEAT DEMAND AND SOLAR
FRACTION
The heat demand QD=c.m.(θHW- θCW)
 the heat capacity of water [cH2O = 1.163
Wh/(kg K)] , t...
Hot Water Demand of Residential
Buildings in Germany
Hot water
demand in
litres/(day and
person)
ϑHW = 60°C
Low demand 10-...
Hot Water Demand of Hotels, Hostels
and Pensions in Germany

Room with
bath
Room w/
shower
Hostels and
pensions

Hot water...
SOLAR FRACTION


It describes the share of the heat demand
provided by the solar thermal system.



solar fraction SF

W...
Solar Fraction as a Function of the
Collector Surface

Note: Location: Berlin, Collector Inclination: 30°, Heat Demand: 10...
Economics
Well established market in Germany.
Overall upward trend of installed solar thermal capacity.
About 7.9 GWth sol...
Annually installed Solar Thermal
Power (0,7 kWth / m²) in Germany
German market for solar thermal
systems
Standard system for
DHWS
 Typical data for 4personshousehold:
 5-6 m² collector ...
Typical Solar Thermal CombiSystem









Combined solar thermal
system for DHW and
room heating support
8-15 m² col...
Installed Solar Thermal Power in
2007 (0.7 kWtherm / m²)

Optional
Flat Plate Collectors newly installed
in Germany in 2008
( Total : ~ 1.960.000 m2 )
Optional
Evacuated Tube Collectors newly
installed in Germany 2008
( Total : ~ 225.000 m2 )
Optional
German incentive program (MAP)
Paymerts provided by the program for solar
thermal systems
Payments base upon investement c...
Paymerts provided by the program for
solar thermal systems
Including base and bonus payments: incentive
rate of 11.5 %
 I...
Summary


Solar thermal systems are cost effective at low
temperatures for water heating or cooking and
space heating.
References






Deutsches Institut für Normung e.V., DIN (1996) DIN
EN 1057, Copper and CopperAlloys – Seamless, Round...
References








Kleemann, M.; Meliß, M. (1993) Regenerative Energiequellen.
Berlin, Springer
Lien, A. G.; Hestenes...
References






SPF Institut für Solartechnik (2002) SPF Info CD 2002 Thermal
Solar Energy.Rapperswil, SPF
TiNOX GmbH...
Thanks!
I will be happy to answer questions
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Low temparature solar thermal technology

  1. 1. Low Temparature Solar Thermal Technology Supervisor: Professor Herbert kabza Prepared By: A.S.M. Abdul Hye Energy Science Seminar
  2. 2. Energy-Resources word-wide Energy Cubes: the Annual Solar Irradiation Exceeds Several Times the Total Global Energy Demand and All Fossil Energy Reserves Energy Resources word wide – all Renewable
  3. 3. What is Solar Thermal?  Uses sun energy for thermal energy Courtesy: xolar group
  4. 4. Thermal use of solar energy
  5. 5. Low Temperature Solar collectors   Flat plate collectors Evacuated tube collector
  6. 6. Flat plate collectors Courtesy: estif
  7. 7. Processes in a Flat-plate Collector
  8. 8. Glazed Flat Plate
  9. 9. Unglazed Flat plate collectors
  10. 10. Flat plate collectors  Pros are: - cheaper to purchase. -Non.tracking option -Diffuse solar radiation utilization  Cons are: - heavier to install (thereby potentially increasing installation costs). - if any part of the panel is broken, a whole-panel replacement is required. - less efficient than vacuum-tube. - a greater collector area is required to match the same energy output as a vacuum tube collector. - dirt collects on the panel and over time reduces efficiencies further.
  11. 11. Evacuted-tube Collectors
  12. 12. Heat pipe evacuated tube array Source: reuk.co.uk
  13. 13. Evacuated U-tube array Source: reuk.co.uk
  14. 14. Evacuted-tube Collectors Pros are: -Very low heat loss. -Eliminate convective loss. -High efficiencies at high temperatures. - light and therefore easier to install (hence reducing install costs). - if one of the tubes breaks or fails, tube replacement is simple and cheap (the whole panel does not need replacing). - more efficient than flat-plate collectors by around 20%. - smaller collector area required to match energy output of flat-plate collectors. - stay clean given the cylindrical shape of the tubes. Hence efficiency of panel is maintained. Cons: - higher initial cost
  15. 15. Energy Conversion in the Solar Collector and Possible Losses Source: Wagner and Co, 1995
  16. 16. Energy Conversion in the Solar Collector and Possible Losses The sum of The reflectance ρ, absorptance α and transmittance τ must always be equal to one. ρ+ α+ τ=1. The corresponding radiant powers are: Φe=Φρ +Φα +Φτ= ρ .Φe+ α .Φe+τ.Φe
  17. 17. How much energy does a solar collector provide? Graph of efficiency and temperature ranges of various types of collectors (radiation: 1000 W/m²)
  18. 18. Conversion Factor
  19. 19. Flat plate vs Evacuted tube Optional
  20. 20. Flat plate vs Evacuted tube Optional source: wikipedia energy output (kW.h/day) of a flat plate collector (blue lines; absorber 2.8 m2) and an evac. tube collector (green lines; absorber 3.1 m2. A field trial illustrating the differences discussed in the figure on the left. A flat plate collector and a similar-sized evacuated tube collector were installed adjacently on a roof, each with a pump, controller and storage tank.
  21. 21. Efficiency Comparison between collectors
  22. 22. Thermal Storage   Short-term storage systems. Long-term storage systems. Large storage systems can be: • artificial storage basins • rock caverns (cavities in rocks) • aquifer storage (groundwater storage) • ground and rock storage. 
  23. 23. Different Types Of Heat Storage There are different types of heat storage such as: • Storage of sensible (noticeable) heat • Storage of latent heat (storage due to changes in physical state) • Thermo-chemical energy storage.  Table Parameters of Low-temperature Storage Materials
  24. 24. Sytem layouts   Open loop Closed loop
  25. 25. Open Loop Systems Courtesy: Design handbook by MPMSAA
  26. 26. Closed loop Systems Courtesy: design handbook by MPMSAA
  27. 27. Heat transfer medium Selections Water >Nontoxic and inexpensive . >With a high specific heat, and a very low viscosity, it's easy to pump > Disadvantage: water has a relatively low boiling point and a high freezing point
  28. 28. Heat transfer medium Selections Non-toxic propylene glycol(in frost condition) > Most common fluid used in closed solar water heating system > Ethylene and propylene glycol are ´´antifreezes´´ Dis Advantage: Most glycols deteriorate at very high temperatures
  29. 29. Heat transfer medium Selections Air >Will not freeze or boil. >Non-corrosive. >Dis Advanteges: >very low heat capacity. >Tends to leak out of collectors, ducts, and dampers.
  30. 30. Technology aspects   Systems for domestic hot water Systems for space heating
  31. 31. Thermosiphon (or: natural flow) systems
  32. 32. Forced circulation systems
  33. 33. Solar combisystem • deliver solar energy to heat store (s) with as low heat loss as possible; • distribute all the heat needed to hot water and space heating demand; • reserve sufficient store volume for auxiliary heating taking into account minimum running time for the specific heater; • low investment costs; • low space demand; • easy and failure safe installation.
  34. 34. Freezing Few common strategies to prevent damage from freezing: >Polypropylene glycol >Drain down >Pump circulation >Insulation of piping >Collector selection
  35. 35. HEAT DEMAND AND SOLAR FRACTION The heat demand QD=c.m.(θHW- θCW)  the heat capacity of water [cH2O = 1.163 Wh/(kg K)] , the taken water mass m,  the cold water temperature ϑCW and the  warm water temperature ϑHW
  36. 36. Hot Water Demand of Residential Buildings in Germany Hot water demand in litres/(day and person) ϑHW = 60°C Low demand 10-20 Average demand High demand Hot water demand in litres/(day and person) ϑHW = 45°C 15-30 Specific heat content in Wh/(day and person) 600-1200 20-40 30-60 1200-2400 40-80 60-120 2400-4800
  37. 37. Hot Water Demand of Hotels, Hostels and Pensions in Germany Room with bath Room w/ shower Hostels and pensions Hot water demand in litres/(day and person) ϑHW = 60°C 95-138 Hot water demand in litres/(day and person) ϑHW = 45°C 135-196 5500–8000 50-95 74-135 3000–5500 25-50 37-74 1500–3000 Specific heat content in Wh/(day and person)
  38. 38. SOLAR FRACTION  It describes the share of the heat demand provided by the solar thermal system.  solar fraction SF Where
  39. 39. Solar Fraction as a Function of the Collector Surface Note: Location: Berlin, Collector Inclination: 30°, Heat Demand: 10 kWh/day
  40. 40. Economics Well established market in Germany. Overall upward trend of installed solar thermal capacity. About 7.9 GWth solar thermal installed until end of 2008 in Germany - over 1/3 of installed systems in EU. Imporatnt factor for successful growth of solar thermal market in germany is MAP. 20% raise per year though different in 2009.
  41. 41. Annually installed Solar Thermal Power (0,7 kWth / m²) in Germany
  42. 42. German market for solar thermal systems Standard system for DHWS  Typical data for 4personshousehold:  5-6 m² collector area  300-400 l. solar storage tank  Costs ~ 4.000 – 5.000 Euro incl. Installation  Market share: ~45%
  43. 43. Typical Solar Thermal CombiSystem      Combined solar thermal system for DHW and room heating support 8-15 m² collector area 500-1.000 liter combi storage tank Costs 10.000 - 15.000 Euro Market share: ~55%
  44. 44. Installed Solar Thermal Power in 2007 (0.7 kWtherm / m²) Optional
  45. 45. Flat Plate Collectors newly installed in Germany in 2008 ( Total : ~ 1.960.000 m2 ) Optional
  46. 46. Evacuated Tube Collectors newly installed in Germany 2008 ( Total : ~ 225.000 m2 ) Optional
  47. 47. German incentive program (MAP) Paymerts provided by the program for solar thermal systems Payments base upon investement costs, not upon energy output  Related to installed collector area >average investment per m^2 collector area: 900 € > Average amount of incentive per m^2 Ac: 118 €  Additional stimulation for innovations through bonus incentives  Overall volume of 196 million € in 2008 
  48. 48. Paymerts provided by the program for solar thermal systems Including base and bonus payments: incentive rate of 11.5 %  Installations in private house provide 19% taxes  Basically a tax decreases to 7.5% of system costs  Over 1.3 GWth new solar thermal installations in 2008 and most installed systems are DHW (4 m^2 collector areaand 300 litre tank)and combisystems (11.5 m^2 collector area and 850 litre tank). 
  49. 49. Summary  Solar thermal systems are cost effective at low temperatures for water heating or cooking and space heating.
  50. 50. References    Deutsches Institut für Normung e.V., DIN (1996) DIN EN 1057, Copper and CopperAlloys – Seamless, Round Copper Tubes for Water and Gas in Sanitary and Heating Applications. Berlin, Beuth Press Hahne, E.; Kübler, R. (1994) Monitoring and Simulation of the Thermal Performance of Solar Heated Outdoor Swimming Pools. Solar Energy vol 53, pp9–19 Khartchenko, N. (1998) Advanced Energy Systems. New York, Taylor and Francis Group
  51. 51. References      Kleemann, M.; Meliß, M. (1993) Regenerative Energiequellen. Berlin, Springer Lien, A. G.; Hestenes, A. G.; Aschehoug, O. (1997) The Use of Transparent Insulation in Low Energy Dwellings in Cold Climates. Solar Energy vol 59, pp27–35 Ladener, H. (1995) Solaranlagen. Staufen, Ökobuch Verlag Manz, H.; Egolf, P. W.; Suiter, P.; Goetzberger, A. (1997) TIMPCM External Wall System for Solar Space Heating and Daylighting. Solar Energy vol 61, pp369–379 Smith, C. C.; Löf, G.; Jones, R. (1994) Measurement and Analysis of Evaporation from an Inactive Outdoor Swimming Pool. Solar Energy vol 53, pp3–7
  52. 52. References     SPF Institut für Solartechnik (2002) SPF Info CD 2002 Thermal Solar Energy.Rapperswil, SPF TiNOX GmbH (2004) TiNOX Absorbers. Available at http://www.tinox.com Verein Deutscher Ingenieure, VDI (1982) VDI 2067 Blatt 4. Economic Calculation of Heat-consumption: Installation of Warm Water Supplies. Düsseldorf, VDI press Wagner & Co. (Hrsg.) (1995) So baue ich eine Solaranlage, Technik, Planung und Montage. Cölbe, Wagner & Co. Solartechnik GmbH
  53. 53. Thanks! I will be happy to answer questions

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