tubes solar (heat storing material)
TRANSCRIPT
Over View
• Tube solar is the conversions of sunlight into renewable energy for water heating , using a solar thermal collector solar water heating (SWH) comprise technologies that are used world wide increasingly
Solar water heating system(SWH)
• SWH systems were discovered in 19th century• Greece, Cyprus and Spain the leaders in the use of
SWH systems, with 30-40% of homes using them
• Here, in Jordan the cost of SWH system is about
900
Selection of heat storing material
• Function: heat storing medium
• Objective: maximum heat storing per unit cost
• Constraints: heating time ~ 10 hours maximum temperature ~ 65 �
• Free variables: material choice
Material index calculation• Heat content Ԛ= wˑρ Cp ΔT
Where w: thickness of layer
Cp: heat capacity
• Thermal diffusivity a= (w^2) / 2t where t: time
• Ԛ= (2t)^2 ΔT (λ / a^0.5)
• Only λ and a are variables, then the material index (MI) = (λ / a^0.5)
comment COST/m^3 MI’S MATERIALS
Expansive, it may be used as constituent
1900 JD 387.3 PMMA
Suitable, available and efficient
900JD 395.3 Paraffin
Not suitable, used in construction of heat
storage walls
980 JD 1000 Brick
Final material choice
paraffin compound CnH2n+2
• Paraffin hydrocarbon, also called alkane, any of the saturated hydrocarbons having the general formula CnH2n+2, C being a carbon atom, H a hydrogen atom, and n an integer.
• The paraffin's are major constituents of natural gas and petroleum.
Heat storage material
• A heat storage material may prepared from expanded vermiculite (EVM) and paraffin by vacuum impregnation.
• The latent heat approximately 135.5 J/g at the melting temperature of 48.0°C, when the paraffin content was 67%.
• The composite exhibited excellent thermal stability and has potential application in solar thermal energy storage and solar heating.
References
1- Material selection in mechanical design, Michael F. Ashpy.
2 -Review on thermal energy storage with phase change materials and applications, Atul Sharma.
3- Internet network, Wikipedia and other sources