8.0 Thermal Energy Systems

Frank R. Leslie, B. S. E. E., M. S. Space Technology, LS IEEE

2/4/2010, Rev. 2.0.1

fleslie @fit.edu; (321) 674-7377

www.fit.edu/~fleslie

Crude oil, $74.66, 2/1/10Wholesale RBOB Gasoline, $1.94

In Other News . . .

High Speed Trains (HST) are underfunded and state taxpayers may have to pick up the difference

College/university “green campus groups” active Bemidji State: “One of our signature themes here at

Bemidji State University is environmental stewardship,” said Anna Carlson, an adjunct professor of environmental studies at BSU.

At the forum, Carlson spoke about her CERT-funded greenhouse gas inventory project. She calculated BSU’s greenhouse gas emissions for the past 10 years using Clean Air-Cool Planet’s online calculator. http://www.cleanair-coolplanet.org/toolkit/inv-calculator.php

Reactivate Florida Tech’s Green Campus Group? Compute the campus GHG emissions?

Form an energy club?

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7 Overview of Thermal Energy Systems

Thermal energy is used directly as heat rather than being converted to electricity Of course, a steam turbine might then make

electricityThis energy is available from combustion,

geothermal sources, or solar radiationHere we consider the temperatures of the

energy, methods of collection, transfers of energy, special uses

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8.0 About This Presentation

8.1 Laws of Thermodynamics8.2 Solar Hot Water Heaters8.3 Solar Stoves and Ovens8.4 Air Conditioning8.5 Boiler Systems8.6 Turbines8.7 Thermoelectric Conversion8.8 Shell Oil Reminder8 Conclusion

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8.1 Thermodynamics --- Classical, That is

First Law of Conservation: Conservation of matter and energy Energy may be transformed but is conserved

(ignores nuclear energy to mass )Second Law of Entropy: All matter tends towards

randomness, disorder and minimum energy Work must be done to make more order

(just look at my desk!) Everything falls apart or decays eventually

Third Law: The entropy of a hypothetical pure crystal at absolute zero temperature is zero The molecules are stationary; no energy left in

them

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8.1.1 Heat Sources

Combustion Coal, oil, and natural gas (NG) --- the fossil fuels Biofuel (wood, grasses, beans, corn, etc.)

Solar radiation absorption by solar collectorsTemperature difference: OTEC (Ocean Thermal

Energy Conversion) surface vs. deep ocean temperatures

Radioisotope thermopiles (thermoelectric; Cassini or New Horizons spacecraft; deep ocean transponders)

Chemical exothermic reactions (give off heat; MREs)Hydrogen production by photodissociation of water or

extracted from algae

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8.1.a The Carnot Cycle

The Carnot Cycle is a theoretical engine operation that demonstrates the maximum efficiency possible (can’t build it!)

Using Kelvin absolute temperatures, the efficiency is the difference of the highest input temperature minus the lower exhaust temperature, all divided by the high temperature A perfect engine could work

with equal input and exhaust temperatures; no losses

Real engines cannot exceed the equivalent Carnot efficiency

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Heat loss = QC/QH

QC/QH = TC/TH

Efficiency = 1 – loss= 1 – (TC/TH

)

= (TH-TC)/TH

So, for TH = 825K& TC = 300K,

Carnot Efficiency = = 1- TC/TH

= 1- 300K/825K

= 0.64 or 64%Kelvin = [(°F-32) / (1.8)] + 273

8.1.2 Degrees of Thermal “Quality”; Types of Use

Low temperature quality ~70°F to ~220°F Example: House heating, hot water heating

Medium temperature quality ~220°F to ~500°F Example: Industrial processing, cooking soup

High temperature quality ~500°F to ~10,000°F Example: Materials testing, utility power like

“Solar One” at Barstow CA The Sandia power tower tested missile nose

cones; like Corel™ dinnerware

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8.1.2.1 SEGS (Solar Electric Generating Systems) at Kramer Junction CA --- Parabolic Reflectors

050201 http://www.eia.doe.gov/kids/energyfacts/sources/renewable/solar.html

8.1.2.2 Solar One Daggett (hot oil fluid) near Barstow CA

http://geoimages.berkeley.edu/GeoImages/BainCalif/CAL400/SOLARONE.HTML030127

8.1.3 French Solar Furnace Laboratory

http://geoimages.berkeley.edu/GeoImages/BainCalif/CAL400/SOLARONE.HTML

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Odellio, France capable of 33,000 °Celsius

8.1.3.1 Solar Two Power Tower Diagram

Ref.: http://www.boeing.com/assocproducts/energy/articles/Power_experience.pdf

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8.1.3.2 Cycles of Heat Engines

Carnot Engine – a theoretical or ideal maximum efficiencyengine where η = (1-Tc/Th)*100%

Otto – the conventional 4-stroke automobile engineDiesel – fuel is injected into the hot compressed air

and bursts into flame, expanding and driving the piston down

Sterling and Ericsson Cycle use external combustion or heat --- Sterling engine can run on a coffee cup heat

Brayton Cycle for turbines: separate equipment for compression, combustion, and expansion

Rankine – a turbine cycle using reheat of the steam after the first or high pressure stage

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8.1.3.2.1 Coffee Cup Sterling Engine

jlnlabs.ifrance.com/jlnlabs/images/stirlvid1.jpg

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8.1.3.3 Rankine Engines

030124Ref.: http://engphys.mcmaster.ca/~garlandw/ep716p1/chap4.pdf

8.2 Hot Water Solar Collectors

Batch tank A large water tank is directly heated by the sun Incoming cold water is warmed as the warmer

water leaves the tank for useOpen Cycle (Florida type)

The water is recirculated from a rooftop collector to a heavily insulated hot water heater

The electrical thermostat may be set at 120°F or lower and rarely heats the water except on cloudy days; electrical timer on after sunset (just in case)

Closed Cycle (for freezing areas) A heat exchanger is placed between a circulating

loop containing freezeproof liquid and the drinking water

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8.2.1 A simple batch tank water heater

Ref.: www.solarns.ca/spatial3.jpg

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Water thermosyphons from the panel to the tank

www.metaefficient.com

8.3 Solar Stoves/Ovens

Frenchman Muxiao designed a parabolic solar stove in 1860 Cooking ovens collect the sun’s rays and absorb them in a

black colored interior, producing ~180°F Auxiliary reflective panels around the opening increase the

absorption further and the oven may reach 300°F Much larger units can be used as drying kilns

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http://www.spw.org/spwzimbabweenvironmentprogrammes.htm

www.deathvalleypizza.com/ SCIPlanz.html

8.3.1 Simple but Efficient “Third World” Cook Stoves

A relatively simple clay-fired pot can serve as a stove to replace wood campfires

Wood is burned by pushing it through the hole in the side

Efficiency is improved by directing the heat to the cooking pot

A form is used so many of these can be made at once

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site:www.bramptontanzania.com clay stove

8.3.2 A Large Solar Tracker Oven at Solar Fiesta 2003

This tracker-oven was used to bake three trays of chocolate-chip cookie at a time

This really made an impression on the crowds (and me! Yum!)

Solar Fiesta is held at Albuquerque NM at the Indian Pueblo Center

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8.4.1 Air-to-Air Conditioning

Basic operation The working fluid (refrigerant) is compressed, heating it

(tire pump gets hot as you pump) The fluid passes through a condensor and rejects heat to

the surrounding air or liquid It then passes through an expansion valve and cools,

entering the evaporator to absorb heat from the air stream Temperature differential

The greater the temperature difference at the condenser, the greater the efficiency of heat transfer

Reverse cycle or heat pump If the piping is interchanged by a solenoid valve, the fluid

can absorb it from outside and expel heat in the building Reverse cycle systems have an Energy Efficiency Rating of

six or higher; resistance heating is only 1.0 (100% efficiency)

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8.4.1.1 Heat Pump Efficiencies

The current national efficiency standard for new heat pumps requires heat pumps to meet a minimum of 13 SEER and 7.7 HSPF --- ACEEE

Heating Season Performance Factor (HSPF)

http://www.fsec.ucf.edu/bldg/pubs/pf362/ for a heat pump report

www.wintonsac.com

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8.4.2 Water-to-Air Conditioning

Heat exchanger Rather than conducting/rejecting heat directly into the

air, ground water is passed through a heat exchanger to absorb the heat from the compressed refrigerant

The hot and cold fluids must flow in opposite directions in the exchanger for maximum heat transfer

Corrosion If the ground water corrodes the exchanger, replacement

costs quickly make this approach infeasible and costly Water spray evaporators

A few years ago, mail-order sales of a cheap water spray kit with a solenoid valve were popular

Water was directly sprayed on the condenser fins when the compressor was running; cooled great and corroded away the fins; see corrosion above

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8.5 Boiler Systems

Superheat tubes carry steam to increase its temperature and energy

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http://www.affordable-energy.org/

http://www.lanl.gov/projects/cctc/factsheets/eerco/images/eerco_schematic_small.jpg

8.5.1.1 Engines

Early Cooper engine weighs 130 tonsStephenson County Antique Engine Club,

Freeport, IL, USA. http://www.steamengine.com.au/steam/engines/cooper/index.html

The Florida Flywheelers Club near Ft. Meade (7000 Avon Park Cutoff Rd) has three shows a year; ~2/21-2/24/2010 is one

http://www.ytmag.com/cgi-bin/showgd.cgi

http://www.floridaflywheelers.org/

8.5.1.1.1 Engines

The Florida Flywheelers Club near Ft. Meade (7000 Avon Park Cutoff Rd) has three shows a year; 2/25-2/28/2009 is one

http://www.ytmag.com/cgi-bin/showgd.cgi http://www.floridaflywheelers.org/

http://www.steamengine.com.au/steam/engines/cooper/index.html

8.5.1.2 Other Steam Uses

Indiana University plays this steam calliope at various events!

Shouldn’t Florida Tech have one, too? Or maybe a bandorgan to be different

This is direct from steam to sound

The range is typically about three miles on a quiet day

The original “Boom Car”

caliope8[1].mp3

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8.5.2 Pressurized Fluidized Bed Combustion

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TVA

8.5.3 Heat Recovery Steam Generators (HRSG)

Hot turbine exhaust gases pass through the HRSG where water or steam is heated.

Steam heated above boiling is termed “superheated” and contains more energy Acts like gas instead of

vapor above critical point

This model contains several sections operating at various temperatures and flow rates

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Ref. Babcock-Hitachi HRSG

http://www.bhk.co.jp/english/product/prd_main.htm

8.5.4 Flue Gas Scrubbers (FGS)

This is really an anti-pollution control, but it’s so large that it should be seen to be appreciated

The gas is sprayed with limestone slurry to remove ~90% of the sulfur dioxide & HCl

050201 http://www.tri-mer.com/RGBS/vertical_tower_packed_bed_scrubbers.jpg

8.6.1 Conventional Steam Turbines

These turbines contain many blades having a radius inversely proportional to the pressure

As the pressure falls, the radius must increase to get the same torque per section

Multiple sections are used to allow steam at different temperatures and pressures to all contribute to turning the shaft

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8.6.1 Turbine Types

Types: Conventional steam boiler turbines Aeroderivative (designed from aircraft engines)

Runs on natural gas, kerosene, or oil Microturbines (for stand-alone power

generation) Runs on natural gas Gives off heat for building These may be the basis of a distributed power

network FSEC has installed one at Cocoa FL for

evaluation Now removed, I believe

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8.6.2 Aeroderivative Turbines

Jet engine designs modified to drive a pump shaft were developed and used for the Alyeska Pipeline from Prudhoe Bay to Valdez, Alaska (3 on line and 1 spare)

Later design variants were produced to turn generators(GE shown below)

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http://www.undergroundinfo.com/PGJ/pgj_archive/Oct2000/oct-8.pdf

8.6.3.1 Combined Heat and Power (CHP)

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This Hitachi Waste Heat Recovery Boiler has two separate loops for generating steam and reheating steam

The steam may also be used for industrial processes

                                             

8.6.3.2 Combined Heat, Power, and Chemicals

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Syngas conversion can produce chemicals and other fuels. Hydrogen production is also possible.

                                             

8.6.3.2 Cogeneration: Steam & Hot Water Distribution

Cogeneration systems are designed to wring more energy from the fuel source

The Carnot principle limits the work produced by an engine, but the rejected waste heat may be used elsewhere in a second cycle

Water jackets or additional piping can capture this heat for other uses

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8.6.4 Microturbines

Microturbines (Capstone) have efficiencies of ~80%

Heated water can power an absorption chillerMerritt Square Mall originally had a combined heat

and power unit (~1966; since removed)FSEC (Florida Solar Energy Center) is installing/has

installed a microturbine

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http://www.microturbine.com/pdfs/Harbec%208.5x11.pdf

8.7 Thermoelectric Conversion

Heat is converted to electricity by the Seebeck Effect Electricity can be converted to heat by resistance Electricity can be converted to cooling by the Peltier Effect

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http://www.thermotek.co.kr/technology/img/seebeck.gifhttp://www.chipcenter.com/circuitcellar/december99/cimages1299/c129r22g10.gif

www.profisica.cl

8.7.1 Conventional Thermopiles

Thermopiles are made of dissimilar metals and generate low voltage, high-current, direct current

Voltage step-up (boost) convertors produce a more usable voltage at a lesser current

030124 http://www.realgoods.com/

Warm up your holidays without

wasting energy. Our Woodstove Ecofan

increases your stove's efficiency

without drawing any electricity. The

hotter your stove gets, the faster the fan blades twirl to

provide ultimate comfort on chilly

days.

8.7.2 Radioisotope Thermal Generators (RTG)

RTGs (like SNAP-27) create electricity from the heat of radioactive decay of plutonium 238, having a half-life of 87 years

A thermopile converts heat to electricity with dissimilar metals or semiconductors

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Left: Extracting nuclear fuel from its transport container for insertion into the Radioisotope Thermal Generator (RTG). The RTG is at the astronaut's foot.

http://www.lpi.usra.edu/expmoon/Apollo16/A16_science.html

8.7.3 Magnetohydrodynamics

A conductive plasma of hot gas is sent through a magnetic field

The moving plasma acts like a moving wire, and electricity can be generated across plates on either side of the stream

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http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/imgmag/mhd.gif

8.8 A Shell Oil reminder

030128http://www.starrotor.com

8 Conclusion

Thermal energy conversion remains the predominant use of fuel

Since the fuels are still perceived as cheap, there isn’t much public clamor to change to renewables

Pollution effects are diffuse and overlooked by most people

As the price of conventional fuels increase and renewables decrease, a shift will occur

There must be a long period of overlap of the two technologies to permit development of renewable resources before conventional fuels become difficult to obtain at a reasonable price

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Olin Engineering Complex 4.7 kW Solar PV Roof Array

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Questions?

References: Books

Brower, Michael. Cool Energy. Cambridge MA: The MIT Press, 1992. 0-262-02349-0, TJ807.9.U6B76, 333.79’4’0973.

Duffie, John and William A. Beckman. Solar Engineering of Thermal Processes. NY: John Wiley & Sons, Inc., 920 pp., 1991

Patel, Mukund R. Wind and Solar Power Systems. Boca Raton: CRC Press, 1999, 351 pp. ISBN 0-8493-1605-7, TK1541.P38 1999, 621.31’2136

Sørensen, Bent. Renewable Energy, Second Edition. San Diego: Academic Press, 2000, 911 pp. ISBN 0-12-656152-4.

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References: Websites, etc.

_____________________________________________________________mailto:energyresources@egroups.com www.dieoff.org. Site devoted to the decline of energy and effects upon populationwww.ferc.gov/ Federal Energy Regulatory Commissionwww.google.com/search?q=%22renewable+energy+course%22solstice.crest.org/dataweb.usbr.gov/html/powerplant_selection.html

http://www.alyeska-pipe.com/PipelineFacts/pipelineconstruction.htmlhttp://www.rustyiron.com/engines/stable/ericsson.html hobbyist sitehttp://www.energy.rochester.edu/us/comdhlst.htm cogenerationhttp://www.realgoods.com/ renewable energy consumer productshttp://www.constellation.com/images/generation/plant_oleander.jpg Merchant Plant site:www.bramptontanzania.com clay stove for Africa to replace wood campfireshttp://www.tri-mer.com/RGBS/vertical_tower_packed_bed_scrubbers.jpg FGShttp://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/imgmag/mhd.gif magnetohydrodynamicshttp://www.starrotor.com/indexflash.htm A Brayton cycle engine animated GIFhttp://images.google.com/imgres?imgurl=http://www.sheclabs.com/SolarConcentrator/images/trailer_small.jpg&imgrefurl=http://www.sheclabs.com/SolarConcentrator/SolarConcentrator.htm&h=284&w=213&sz=71&tbnid=FPnEjeS6K4oJ:&tbnh=109&tbnw=82&start=6&prev=/images%3Fq%3Dsolar%2Bconcentrator%26hl%3Den%26lr%3D%26safe%3Dactive%26rls%3DGGLD,GGLD:2004-07,GGLD:enhttp://www.photobiology.com/photoiupac2000/bircan/Index.htmhttp://www.aceee.org/consumerguide/hp.pdfhttp://www.alyeska-pipe.com/default.asp

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Slide stockpile follows!

Older slides follow this one. Look at these if you have interest or time. It’s difficult to decide what to leave out of the lecture to save time!

8.6.2.1 Oleander Power Plant, Cocoa FL

Owned by Southern Power Co.$206M, 680 MWe, selling contracts to Seminole

Electric Cooperative, Inc. and FPL4.2M lb pollutants per yearUses 73M gallons deionized water per yearWater spray cools inlet air to get more powerBurns NG at least 2/3 of the time; low sulfur #2

diesel oil at other times (primarily for backup)Connected to the Florida Gas Transmission LineClose to natural gas pipelineTurbines produce power within 30 minutes of

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8.6.2.1.1 Plant is compactly placed

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Located northeast of I-95 and FL 520

Four turbines with space for one more

Oil is used as backup to natural gas from a major pipeline

http://www.constellation.com/images/generation/plant_oleander.jpg

Had siting controversy with local public