Post on 31-Mar-2015
ELTR 1223Survey of Renewable
Energy Technology
Overview of Solar ThermalApplications
Unit 5
Source:
Use Policy This material was developed by
Timothy J. Wilhelm, P.E., Kankakee Community College, with funding from the National Science Foundation as part of ATE Grant No. 0802786.
All materials in this presentation are designed and intended for educational use, only. They may not be used for any publication or commercial purposes.
Source:
Author, Editors/Reviewers Author: Timothy J. Wilhelm, P.E.,
Kankakee Community College Editors/Reviewers / Modifier: Chris Miller Heartland Community
College
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Objectives Students will be able to describe, in
very simple terms, “black body” absorption and radiation and their relationship to solar thermal applications.
Students will be able to list the basic residential applications for solar thermal technology.
Source:
Objectives Students will be able to discuss the
basic requirements for passive solar architectural design.
Students will be able to discuss and describe how active solar thermal technology works.
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Thermal Applications = Using Heat
Typical Thermal Applications in Daily Human Living – Residential Dwelling Applications:
Space Heating
Water Heating
Cooking
Contemporary Thermal Sources• The Heat Energy Necessary for
Space Heating, Water Heating, and Cooking is typically Converted from:– Electricity– Natural Gas– LPG– Fuel Oil– Coal– Wood– Other Combustible Fuels
Challenges Regarding our Conventional Sources of Thermal Energy
Limited, Finite Supply All (except nuclear-fission sourced
electricity) pump CO2 back into the atmosphere
All result in one or more additional, environmental pollutants
The cost of all is continually increasing
Most are not locally available and must be transported in
Moving Heat Energy to Where We Need it…
Heat is directed and moved via…
IR Radiation Conduction Convection
Conduction, and Radiation
Convection
Source: http://cobblearning.net/rlimpert/files/2010/02/a3a421b29aedfa72.jpg
Conduction, Convection, and Radiation
Source: http://cobblearning.net/rlimpert/files/2010/02/a3a421b29aedfa72.jpg
The Sun as a Source of Thermal Energy• “Black Body” radiation and absorption!• We see only reflected light• When we see “white” light, the “white”
surface is reflecting all frequencies of visible light
• When we see “red” light, the “red” surface is only reflecting the “red” frequency of visible light, and is absorbing all the other frequencies of visible light
• When a surface appears “black” it is absorbing all the frequencies of visible light and reflecting none
“Black Body” Radiation and Absorption “Black Bodies” absorb ALL
frequencies At temps below 200o C, “Black
Bodies” (all bodies) radiate InfraRed frequencies
InfraRed radiation is HEAT!
Source: http://www.popsci.com/files/imagecache/article_image_large/files/articles/colorfire_485.jpg
Solar Thermal Technologies• The basic ideas behind solar thermal
energy are:– Convert solar radiation into heat energy
via Black Body absorption– Trap the captured heat energy
• Limit IR radiation losses• Limit Convective losses• Limit Conductive losses
– Direct the captured heat energy into the desired zone or material via IR radiation, and/or convection, and/or conduction
Solar Thermal Technologies Solar Space Heating vs. Solar
Domestic Hot Water Heating vs. Solar Cooking
Passive vs. Active Solar Thermal Applications
“Flat Plate” Solar Collectors vs. Concentrating Solar Collectors
Solar Space Heating Passive Solar Principles:
Insulate, insulate, insulate (especially the North wall)
Orient long axis of building E-W Lots of South facing glazing Thermal storage Nocturnal insulation on South wall Summer shading to avoid seasonal over
heating
Passive Solar Principles
Source: http://www.energysavers.gov/images/five_elements_passive.gif
Passive Solar Principles
Source: http://www.solarbuildings.ca/c/sbn/img_db/alstonvale.JPG
Passive Solar Principles
Passive Solar Principles
Passive Solar Principles Thermal Storage Media
Solid Thermal Mass Trombe Wall
Water Columns, jugs, and barrels
Eutectic Salts
Passive Solar Principles
Passive Solar Principles
Source: http://www.solar-components.com/BLUETUB.JPG
Passive Solar Principles
Source: http://knowledgepublications.com/heat/images/Solar_Air_Window_Box_Collectors.gif
Active Solar Space Heating Principles Same as Passive principles, but…
Add on external solar collectors Add on fans or pumps to move fluid
Air or water or other FLUID Different configurations of heat storage May incorporate heat pumps May be flat-plate or concentrating
Active-Solar Air-Heating Principles
Active-Solar Air-Heating Principles
Source: http://www.yoursolarlink.com/blog/wp-content/uploads/solar_air_heater.jpg
Active-Solar Air-Heating Principles
Active-Solar Space Heating with Liquid Working Fluids
Source: http://www.solarage.co.uk/res/embedded/swhsystem.gif
Solar Domestic Hot Water Heating
• Can be active or passive (thermo-siphon)
• Can be open loop– Open loop can be drain-down configured
for freeze protection• Can be closed loop
– Closed loop can be drain-back configured for freeze protection
– Closed loop can be freeze protected by using antifreeze as the working fluid
Passive Solar DHW Heating
Batch Tank HeatingThermo-siphon
Passive Solar Water Heating Batch heaters
Passive Solar Water Heating Batch heaters
Passive Solar Water Heating Batch heaters
Source: http://www.byexample.com/library/photos/projects/batch_collector/bc_01697.jpg
Passive Solar Water Heating Thermo-siphon heaters
Source: http://www.altensol.com.ph/?404=Y
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Schematic diagram of a thermosyphon solar water heater
Auxiliary
Storage tank Hot water outlet
Cold water inlet
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Laboratory model
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Typical thermosyphon solar water heater
Active Solar DHW Heating
System Design Governed by Need for System Efficiency and Freeze Protection
Active Solar Water Heating
Source: http://www.amecosolar.com/waterheat.jpg
What type of system would I use in my area?
Warm climates systems similar to those shown
previously systems will differ in design
Cold climates freeze protection becomes critical
Indirect systems with heat exchangers Drainback and draindown systems
Warm climates
• Fluid in tank isheated in collector
• Most common systemin temperate climates
Warm climatesThis system is called a thermosiphon system. It does not have pumps, controllers, or any moving parts. Water is heated and the density of the hot versus cold water takes over from there.
Works off natural thermosiphon actions in moving the water heated in the collector back to the tank and the cold water in the tank to the collector.
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Direct circulation system
Cold climates
• Freeze protection
• Reduce Scale
• Non-potable fluids
Cold climates
Indirect system with heat exchanger that contains fluids in collector that do not freeze. Heat exchanger is in the water heater.
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Drain-down system
When a freezing condition or a power failure occurs, the system drains automatically by isolating the collector array and exterior piping from the make-up water supply and draining it using the two normally open (NO) valves
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Indirect water heating system
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Drain-back system
Circulation continues as long as usable energy is available. When the circulation pump stops the collector fluid drains by gravity to a drain-back tank.
Cold climates
Indirect system with heat exchanger that contains fluids in collector that do not freeze. Heat exchanger is external to the water heater.
Cold climates
T
Solar Tank
T
Cold Supply
M
Drain Back Tank
C
PP T
Drainback systemIn this system all the water in the collector drains back into a reservoir.
Cold climates
In this system, all the water in the collectors drains out of the collector.
Draindown system.
Cold climateAnother thermosiphon system similar to the one used in warm climates, but this one has a heat exchanger incorporated in the system to protect the collector during freezes.
Source: http://mashav.com/solar-energy/sirt.jpg
Stationary Collectors for DHW
Flat Plate Collectors“Paint” or Selective SurfaceEvacuated Tube Collectors
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Flat-plate collector
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Flat-plate Collectors
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Types of flat-plate collectorsWater systems
GlazingRiserAbsorbing plate
Insulation
A
BGlazingRiserAbsorbing plate
Insulation
CGlazingRiserAbsorbing plate
Insulation
DGlazingRiserAbsorbing plate
Insulation
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Schematic diagram of an evacuated tube collector
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Evacuated tube collectors
Source: http://www.lightheat.com/home_heating/images/thermomax3.jpg
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Swimming pool heating -- Another water heating application
Source: http://build-it.hit.bg/solar.html
Concentrating Collectors
Non-Imaging ConcentratorsTracked, Imaging Concentrators
Refractive vs. Reflective
Refractive Concentrators
Refractive, Imaging Concentrators
Lenses!
Source: http://3.bp.blogspot.com/_vaXUruXsufA/SxOLacmQNyI/AAAAAAAAB5s/0mTAthc_JnI/s200/F_23_2.gif
Refractive, Imaging Concentrators
Lenses!
Source: http://oscar.iitb.ac.in/images/weeklyimages/Physics/single_lens.jpg
Refractive, Imaging Concentrators
Lenses!
Source: http://artofmanliness.com/wp-content/uploads/2008/04/magnifying-glass.jpg
Refractive, Imaging Concentrators
Lenses!
Reflective ConcentratorsNon-Imaging…
Tracking not needed.
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Flat plate collector with flat reflectors
Sun rays
Flat reflector
Flat plate collector
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Schematic diagram of a CPC collector
θc
Reflective ConcentratorsImaging…
Tracking Required!
Parabolic Solar Concentrators Reflective Imaging Concentrators
Specially-shaped, highly polished surfaces that “reflects” light rays, focusing them to a very sharp point on the light-source-side of the reflector…MANY more W/m2 into a VERY small mass or space = MUCH higher temperatures.
These are all based on the geometry of the parabola. Line focused = HOT…single-axis tracking
required Point focused = HOTTER…dual-axis tracking
required
Line-Focus Reflectors
Source: http://www.reuk.co.uk/OtherImages/parabolic-trough2.jpg
Source: http://cache.io9.com/assets/resources/2007/11/suncollector.jpg
Source: http://teamsuperforest.org/superforest/wp-content/uploads/2010/10/parabolic-trough-500x334.jpg
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Parabolic trough collectors
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Parabolic Trough System
Source: http://www.volker-quaschning.de/artikel/konzenson2/abb2.jpg
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Parabolic trough collectors
Source: http://www.tristategt.org/images/NREL-Solar-Troughs-02.jpg
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Parabola detail
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Receiver detail
Source: http://erenovable.com/wp-content/uploads/2009/05/solarpowerplant-thumb.jpg
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Schematic of a parabolic dish collector
Parabola
Sun rays
Receiver
Two-axes tracking mechanism
Point-Focus Reflectors
Source: http://keetsa.com/blog/wp-content/uploads/2008/06/solar-dish-1.jpg
Solar-Thermal Process-Heat Applications
Solar cooking High temperature boilers for steam
engines Low temperature boilers for ORC
engines Stirling-cycle external combustion
heat engines The Minto Wheel …and, MORE
Solar Cooking – Non-imaging
Source: http://www.builditsolar.com/Projects/Cooking/BillsPage.jpg
Solar Cooking -- Imaging
Source: http://wohnen.pege.org/2005-afrika/solarkocher.jpg
Solar Cooking, Single Hot Dog Scale
Source: http://westernpower.com.au/pluginkids/
Village- Scale Solar Cooking
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Very High Temp Power Tower!
Source: http://ec.europa.eu/energy/res/sectors/images/solar_3.jpg
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Schematic of central receiver system
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Tower detail
Source: http://earth2tech.files.wordpress.com/2009/07/solarthermalgenericnrel.jpg?w=250&h=159
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Heliostat detail
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Mini-Boiler
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Mini-Boiler
Source: http://tonto.eia.doe.gov/energyexplained/images/stock/solarth.jpg
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Central receiver-3
Source: http://www.energy.gov/images/gallery/25Years-1996-1998/album_photo96-2_rdax_253x202.jpg
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Central receiver-4
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Central receiver-5
Source: http://www.ecotec2000.de/grafics/10kW.jpg
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Mini-Boiler
Source: http://bayern.zentrumspartei.de/images/flugzeug_sbp.jpg
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Mini-Boiler
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Mini-Boiler
Organic Rankine Cycle Engine
Stirling Cycle Engine
The Minto Wheel
Design Problem Commercial-size Solar Greenhouse Challenges:
Maximum sunlight means minimum structure
They typically melt off the snow load! Nocturnal insulation in a 2,000 square
foot building? Thermal storage? What would you do?