overview of solar thermal applications

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

Source:

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


Source: http://www.solarbuildings.ca/c/sbn/img_db/alstonvale.JPG

Passive Solar Principles Thermal Storage Media

Solid Thermal Mass Trombe Wall

Water Columns, jugs, and barrels

Eutectic Salts


Source: http://www.solar-components.com/BLUETUB.JPG


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


Source: http://www.yoursolarlink.com/blog/wp-content/uploads/solar_air_heater.jpg

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

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

TEI Patra: 3-18 July 2006

Intensive program: ICT tools in PV-

systems Engineering

Schematic diagram of a thermosyphon solar water heater

Auxiliary

Storage tank Hot water outlet

Cold water inlet

TEI Patra: 3-18 July 2006Intensive program:

ICT tools in PV-systems Engineering

Laboratory model



systems Engineering

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.



systems Engineering

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.



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



systems Engineering

Indirect water heating system



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 S upply

M

Drain B ack 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



systems Engineering

Flat-plate collector



Flat-plate Collectors



Types of flat-plate collectorsWater systems

GlazingRiserAbsorbing plate

Insulation

A

BGlazingRiserAbsorbing plate

Insulation

CGlazingRiserAbsorbing plate

Insulation

DGlazingRiserAbsorbing plate

Insulation



systems Engineering

Schematic diagram of an evacuated tube collector



systems Engineering

Evacuated tube collectors

Source: http://www.lightheat.com/home_heating/images/thermomax3.jpg



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


Lenses!

Source: http://oscar.iitb.ac.in/images/weeklyimages/Physics/single_lens.jpg


Lenses!

Source: http://artofmanliness.com/wp-content/uploads/2008/04/magnifying-glass.jpg


Lenses!

Reflective ConcentratorsNon-Imaging…

Tracking not needed.



Flat plate collector with flat reflectors

Sun rays

Flat reflector

Flat plate collector



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



systems Engineering

Parabolic trough collectors



Parabolic Trough System

Source: http://www.volker-quaschning.de/artikel/konzenson2/abb2.jpg



Parabolic trough collectors

Source: http://www.tristategt.org/images/NREL-Solar-Troughs-02.jpg



Parabola detail



Receiver detail

Source: http://erenovable.com/wp-content/uploads/2009/05/solarpowerplant-thumb.jpg



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

http://www.youtube.com/watch?v=U220eTxHmvw

Solar Cooking, Single Hot Dog Scale

Source: http://westernpower.com.au/pluginkids/

http://www.pspb.org/e21/media/SolarCooker.swf

Village- Scale Solar Cooking



Very High Temp Power Tower!

Source: http://ec.europa.eu/energy/res/sectors/images/solar_3.jpg



Schematic of central receiver system



Tower detail

Source: http://earth2tech.files.wordpress.com/2009/07/solarthermalgenericnrel.jpg?w=250&h=159



Heliostat detail



Mini-Boiler



Mini-Boiler

Source: http://tonto.eia.doe.gov/energyexplained/images/stock/solarth.jpg



Central receiver-3

Source: http://www.energy.gov/images/gallery/25Years-1996-1998/album_photo96-2_rdax_253x202.jpg



systems Engineering

Central receiver-4



Central receiver-5

Source: http://www.ecotec2000.de/grafics/10kW.jpg



Mini-Boiler

Source: http://bayern.zentrumspartei.de/images/flugzeug_sbp.jpg



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?

overview of solar thermal applications

Documents

radiation source

solar radiation

solar thermal energy

solar thermal applications

radiation convection

solar domestic

red light

basic residential applications