Ch 5-Solar Thermal Energy Conversion Systems
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Transcript of Ch 5-Solar Thermal Energy Conversion Systems
Ch 5. SOLAR THERMAL ENERGY CONVERSION SYSTEMS
SOLAR WATER HEATINGSOLAR DISTILLATIONSOLAT THERMAL POWER PLANT Low Temperature Solar Power Plant Medium Temperature Solar Power Plant High Temperature Solar Power Plant CENTRAL RECEIVER POWER PLANTSOLAR PONDSSOLAR PUMPINGSOLAR AIR HEATERSSOLAR FURNACESOLAR COOKERSSOLAR PASSIVE TECHNIQUES
SOLAR WATER HEATING(Thermosiphon System)
• Flat plate collector with transport glass
• Bottom of the tank at least 0.3m top of the collector
• Circulation occurs through natural convection or thermo siphoning
• Heated water with low density rises and flows into the top of the storage tank. The higher density cold water tends to sink and flows lower heater of flat plate
• The density difference provides driving effect
SOLAR DISTILLATION• Converting saline water into distilled
water in solar still.• Blackened basis containing saline
water on which a transparent glass covers.
• Solar radiation passes through cover and energy is absorbed by blackened surface.
• Water is heated and vapor produced is condensed to purified water on cooler interior of roof.
• Condensed water is flowing down the sloping roof and is collected.
Efficiency =W (h2-h1)/H where W = weight of distillated
water per m2 per day h2 - h1 enthalpy change from vapor
to water and H = solar intensity.15-20 liters per day per 10 m2
SOLAR PUMPING:• Utilization of power generated by
solar energy for water pumping, useful for irrigation
• It consists of:• Solar collector- there are two
kinds Flat plate and concentrator collector
• Heat transport system • Boiler or heat exchanger• Heat engine- there are two-
Rotary piston engine and Reciprocating engine.
• Condenser• Pump – Reciprocating and Rotary
pump
Solar Air Heaters
• Getting high temperature by concentrating solar radiation onto a specimen .
• Heliostat: optically flat , polished flat plate
• Spherical reflecting collectors: highly polished aluminum or silver coated surface.
• It produces 2800 0c or maximum heat flux:16000 Kw/m2
• Advantages • Heating is carried out without any
contamination • Temp can be controlled by changing
the position of material in focus• Gives extremely high temp • Provides rapid heating• Limitations• It is limited to sunny days (4-5hrs)• High cost
SOLAR FURNACE
Solar Cooker
SPACE PASSIVE HEATING PASSIVE HEATING SYSYTEMS• Direct gain• (Indirect Gain)Thermal storage wall
• Solar radiation is collected by some elements of structure or admitted directly into building through large south facing windows.
• Which operates without pumps, blowers or any other mechanical devices• Air is circulated past a solar heated surface and through the building by
convection.
THERMAL STORAGE WALL
• A large wall which absorbs solar radiation and stores heat which is placed behind south facing windows
• The air is heated between glass cover and wall. The heated air rises and enters the adjacent room through vents at the top of the wall and air circulates by natural convection
BASIC HOT WATER SYSTEM• Flat plate collector located on the roof
of the building• Heat is transmitted to water in the
storage tank• When the temperature falls below, the
water will pass through auxiliary heater• During normal operation through air
heat exchanger, air is heated and passes through 3 way valve then to the distribution system.
• During cloudy days, air passes through the auxiliary heater then to the distribution system
Advantages:• No temperature drop during transfer of
energy• Requires relatively smaller storage
volume• It can be used in absorption air
conditioner Disadvantages:• Water heater may operate at excessive
high temperature, care must be taken to avoid boiling and pressure build up
• Care must be taken to avoid corrosion problems
BASIC HOT AIR SYSYTEM Advantages:• No freezing problem• Minimum corrosion problem• Since working fluid is air, warm
air heating system is in common Disadvantages:• Relatively higher power cost for
pumping air through storage medium
• Large storage volume
Air Distribution
Electric Power Generation Using Thermal Storage