Unit-2 1. Solar Energy Collectors working.pptx

Renewable energy systems

1. RENEWABLE ENERGY SYSTEMS Professional Elective – I III year I SEM, EEE Course Code – 20EE31004 A.Y 2024-25 Department of Electrical and Electronics Engineering @GCET 24 Lecturer: G.Bhagath Assistant Professor Geethanjali College of Engineering and Technology

2. Department of Electrical and Electronics Engineering @GCET 24 Unit -2 : Solar Energy Collectors Flat plate and concentrating collectors Classification of concentrating collectors Orientation and thermal analysis Advanced collectors Renewable Energy Systems - Syllabus Solar Energy Storage Different methods of storage system Stratified Storage Solar ponds Applications of Solar Energy Solar Heating/ cooling techniques Solar distillation and drying Photovoltaic energy conversion

3. Department of Electrical and Electronics Engineering @GCET 24 Solar Energy Collectors What are solar collectors? Different types of solar collectors Conversion of solar radiation into heat Renewable Energy Systems

4. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Solar collector is a device for collecting solar radiation and transfer the energy to a fluid passing in contact with it. General classification of solar collectors: Flat plate type solar collector Concentrating type solar collectors In flat plate type solar collectors, the collector area is same as the absorbers area. In concentrating type solar collector, the area intercepting solar radiation may be hundred of time greater than the absorber area ( Higher temperature and efficiency can be achieved)

5. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems

6. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Physical principle of the conversion of solar radiation into Heat: Greenhouse Effect Glass transmits Short wave radiation Radiation absorbed – heat energy – conducts – surroundings Reradiation results in Long wave radiation Long wave radiation is now trapped inside Solar Energy Collector Flat Plate Collectors Concentrating collector

7. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems - Flat Plate Collectors Flat plate collectors are classified as: Liquid heating collectors Solar air heaters (Non-porous absorber & porous absorber collectors) Depending on the type of heat transfer fluid (design of the passage)used Components of flat plate collectors: Transparent cover Tubes, Fins, Passages or channels Absorber Plate Insulation Casing or container

8. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Components of flat plate collectors: Transparent cover Transparent – Glass ( 3 to 4mm) - Plastic sheet Transmissivity of cover ( snell’s law) Two consecutive covers Tubes, Fins, Passages or channels Passage of medium(air, water, salts) Design is integrated with collector absorbers Absorber Plate Absorber or traps heat energy Insulation Fiber Glass – styro foam(5 to 10cm) Casing or container

9. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems

10. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Transparent cover Double glass covers Reduces losses due to air convection Traps IR radiation Antireflective coatings – HCl – MgF2, primer, Cr2O3 ----0.15 t0 2micro meter thickness Conduction – convection – radiation Heat transport system Heat trapped – heat transport (water/ air) – metal tubes Slope – cooler water ( bottom) – hot water (top) Absorber – black coated – corrugated ----ridges / grooves (series and parallel) Water medium drawbacks Freezes(ethanol glycol) – corrosion ( copper tubing , chemical treatments)

11. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Air stream – heated – by backside of collector plate Fins increase contact surface Collector orientation facing south- inclination angle 15 degree Advantages: Power to pump is less for low rating applications Eliminates problems faced by water medium Disadvantages: Energy transfer is less efficient Examples Drying or curing of agricultural products Space heating for comfort Regeneration of dehumidifying agent Seasoning of timber

12. Department of Electrical and Electronics Engineering @GCET 24 Renewable Energy Systems Non-porous Absorber Air stream doesn’t flow through the absorber plate Air flow above and below plate Porous absorber Porous absorber that include slit, expanded metal, honeycomb or overlapped glass plate absorber