Solar Crop Drying Topics

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Solar Crop Drying

Efficient, Simple, Cost Effective and Building Integrated

Presented by: Project funding provided by:

John Hollick, P.E. Conserval Systems Inc.

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(3)

Solar Crop Drying Topics

•

• ICATICAT •

• What is a transpired solar collector?What is a transpired solar collector? •

• How solar crop drying worksHow solar crop drying works •

• System details/designSystem details/design •

• Demonstration ProjectsDemonstration Projects •

• Environmental benefitsEnvironmental benefits •

• Economics of solar crop dryingEconomics of solar crop drying •

• IEAIEA •

• Future solar crop drying potentialFuture solar crop drying potential •

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Innovative Clean Air

Technology Program (ICAT)

“ICAT funds technically solid projects that

can demonstrate the commercial utility in

California of technical innovations that will

improve emission prevention and control.”

– California Air Resources Board

(5)

Transpired solar collector

After years of R & D, it was found that a

single, non-glazed perforated panel was

more efficient and less expensive

“The transpired solar collector is a thin

sheet of dark perforated metal. The dark

wall absorbs solar radiation and heats

fresh air drawn through its perforations by

a building's ventilation fans.”

a building's ventilation fans.” (National Renewable(National Renewable Energy Laboratory (NREL))

(6)

Panel Properties

•

• Panels can be specified as aluminum orPanels can be specified as aluminum or steel

steel

•

• Wide variety of standard colors availableWide variety of standard colors available •

• Over 240 perforations per ftOver 240 perforations per ft22

•

• CorrugatedCorrugated to increase

to increase

structural

rigidity

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Crop Drying Basics

•

• Drying requires air movement and heatDrying requires air movement and heat •

• Warm air absorbs more moisture thanWarm air absorbs more moisture than cold air

cold air

•

• Increasing air flow or heat reducesIncreasing air flow or heat reduces drying time

drying time

•

• Fossil fuels generally provide heatFossil fuels generally provide heat source

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How Solar Crop Drying Works

•

• Sun shines on the solar collectorSun shines on the solar collector •

• Air is drawn through tiny perforationsAir is drawn through tiny perforations •

• Heated air is drawn to the top of theHeated air is drawn to the top of the

system and into the dryer via the dryer

fan

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Main components of a solar crop drying system Crop Dryer

Material to be Dried

Dryer Fan/Burner Solarwall

Panel

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The Solarwall panel absorbs the sun’s energy Solarwall

Panel

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The boundary layer air is heated and drawn through tiny perforations into the air space Solarwall

Panel

Air Space

Profiled Sheet Provides Wind Boundary Layer

Perforation

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Solarwall Panel

Air Space

Profiled Sheet Provides Wind Boundary Layer

Outside Air is Heated and Passed

through Absorber

Perforation

Air Space Under Negative Pressure

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The heated air travels up to the air intake and is drawn into the dryer

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Additional heat is provided by the burner (if required) and the air passes through the material being dried Solarwall

Panel

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Heat loss through the roof is recovered when the fan is running

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Solar Drying

•

• Dries all types of produceDries all types of produce •

• Excellent for tea, coffee, fruit, spices, rubber,Excellent for tea, coffee, fruit, spices, rubber, cocoa beans, rice, timber, nuts and manure

cocoa beans, rice, timber, nuts and manure

•

• Suitable for laundry drying & otherSuitable for laundry drying & other commercial products

commercial products

•

• Works with tunnel, trough, conveyor andWorks with tunnel, trough, conveyor and other types of driers

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Typical Installation

•

• Panels are installed 6 – 12 inches from roofPanels are installed 6 – 12 inches from roof •

• Can be installed over or around existing roofCan be installed over or around existing roof openings

openings

•

• Can be installed over any non-combustible,Can be installed over any non-combustible, waterproof roof membrane

waterproof roof membrane

•

• Easy installation –Easy installation – no special skills

no special skills

or tools needed

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0 5 10 15 20 25 30 35 40 45

100 200 300 400 500 600 700 800 900 1000 Solar Radiation - Watt/m2_{of Transpired Collector}

Solar Radiation - BTU/ft2_{of Transpired Collector}

A

ir

Tem

p

eratur

e Rise - Deg. C

A

ir

Tem

p

eratur

e Rise - Deg. F

Air Temperature Rise vs. Solar Radiation for Various Air Flow Rates

50 100 150 200 250 300

0 0 0 10 20 30 40 50 60 70 80 A B C

.1.1 CFM/ft2_{(20 m}3_/h/m2₎

.4.0 CFM/ft2_{(73 m}3_/h/m2₎

.7.0 CFM/ft2_{(130 m}3_/h/m2₎

Temperature Rise Graph

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Demonstration Projects

With generous support from the California Air

Resources Board, five solar crop drying

systems were installed in California

•

• SunsweetSunsweet (prunes)(prunes)

•

• Carriere & Sons Carriere & Sons (walnuts)(walnuts)

•

• KeyawaKeyawa Orchards Orchards (walnuts)(walnuts)

•

• Korina Farms Korina Farms (pecans)(pecans)

•

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Sunsweet

(prunes)(prunes)

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Sunsweet

(prunes)(prunes)

(22)

Sunsweet

(prunes)(prunes)

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Gas Usage (% Difference) vs. Date

Sunsweet - 2004 Solarwall Monitoring

0 2 4 6 8 10 12 14

07-Aug 09-Aug 11-Aug 13-Aug 15-Aug 17-Aug 19-Aug 21-Aug

Date G as U sag e ( % D if fe re n ce)

Sunsweet

(prunes)(prunes)

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Sunsweet

(prunes)(prunes)

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Sunsweet

(prunes)(prunes)

185° F 185° F Maximum Air Maximum Air Temperature Temperature 100 MMBTU 100 MMBTU

(per month of use)

Projected Savings

10,000

10,000 cfmcfm

(of estimated 50,000

(of estimated 50,000 cfmcfm)) Air Volume Preheated

Air Volume Preheated

1,225 ft

1,225 ft22

SOLARWALL Size

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Carriere & Sons

(walnuts)(walnuts)

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Carriere & Sons

(walnuts)(walnuts)

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Carriere & Sons

(walnuts)(walnuts)

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Carriere & Sons

(walnuts)(walnuts)

(per month of use)

Projected Savings

17,500

17,500 cfmcfm

(of estimated 70,000

(of estimated 70,000 cfmcfm)) Air Volume Preheated

3,200 ft

3,200 ft22

SOLARWALL Size

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Keyawa

Orchards

_Orchards

(walnuts)(walnuts)

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Keyawa

Orchards

_Orchards

(walnuts)(walnuts)

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Keyawa

Orchards

_Orchards

(walnuts)(walnuts)

Air Temperature vs. Time

Keyawa Orchards - 2004 Solarwall Monitoring

50 60 70 80 90 100 110 120

9:30 10:30 11:30 12:30 13:30 14:30 15:30 16:30

Time A ir T em p er at u re ( °F )

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Keyawa

Orchards

_Orchards

(walnuts)(walnuts)

(per month of use)

Projected Savings

65,000

65,000 cfmcfm Air Volume Preheated

9,300 ft

9,300 ft22

SOLARWALL Size

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Korina Farms

(pecans)(pecans)

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Korina Farms

(pecans)(pecans)

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Korina Farms

(pecans)(pecans)

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Korina Farms

(pecans)(pecans)

Korina Farms - 2004 Solarwall Monitoring

40 50 60 70 80 90 100 0.333333 3 0.375 0.416666 7 0.458333 3 0.5 0.541666 7 0.583333 3 0.625 0.666666 7 0.708333 3 0.75 0.791666 7 Time A ir T em p er at u re ( °F )

(38)

Korina Farms

(pecans)(pecans)

(per month of use)

Projected Savings

37,000

37,000 cfmcfm Air Volume Preheated

5,200 ft

5,200 ft22

SOLARWALL Size

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Sonoma County Herb

Exchange

(various herbs)(various herbs)

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Sonoma County Herb

Exchange

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Sonoma County Herb

Exchange

Sonoma County Herb Exchange - 2005 Solarwall Monitoring

50 60 70 80 90 100 110 120

8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00

Time A ir T e m p er at u re ( °F )

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Sonoma County Herb

Exchange

none none Maximum Air Maximum Air Temperature Temperature 3 MMBTU 3 MMBTU

(per month of use)

Projected Savings

350

350 cfmcfm Air Volume Preheated

105 ft

105 ft22

SOLARWALL Size

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ICAT Summary

3 MMBTU 3 MMBTU 163 MMBTU 163 MMBTU 572 MMBTU 572 MMBTU 172 MMBTU 172 MMBTU 100 MMBTU 100 MMBTU Projected Projected Savings Savings (per month) (per month) 12 12 2 2 2 2 2 2 1 1 Months of Months of

Use per Year

Herbs Herbs Pecans Pecans Walnuts Walnuts Walnuts Walnuts Prunes Prunes 350

350 cfmcfm 37,000

37,000 cfmcfm 65,000

65,000 cfmcfm 17,500

17,500 cfmcfm 10,000

10,000 cfmcfm Air Volume

Air Volume

Preheated

105 ft

105 ft22

5,200 ft

5,200 ft22

9,300 ft

9,300 ft22

3,200 ft

3,200 ft22

1,225 ft

1,225 ft22

SOLARWALL SOLARWALL Size Size Sonoma Sonoma Korina Korina Keyawa Keyawa Carriere Carriere Sunsweet Sunsweet

Total Projected Savings (per month): 1,010 MMBTU

Total Cumulative Savings (per year): 1,950 MMBTU

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Solar Air Heating: The

Right

Choice for Agriculture

•

• Fuel is renewable and non-pollutingFuel is renewable and non-polluting •

• Maintenance-freeMaintenance-free •

• Lifetime of free heatingLifetime of free heating •

• Cost effectiveCost effective •

• Government incentives availableGovernment incentives available •

• Socially responsibleSocially responsible •

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International Energy Agency

IEA Task 29 states – “One of the most

promising applications for active solar

heating worldwide is the drying of agricultural

products.”

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International Energy Agency

•

• Lack of awarenessLack of awareness •

• Lack of good technical informationLack of good technical information •

• Lack of good practical experienceLack of good practical experience 3 Key Barriers:

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Café Duran – Panama

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Coopeldos

– Costa Rica

_{– Costa Rica}

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Coopeldos

– Costa Rica

_{– Costa Rica}

(50)

Drying Coir Pith – India

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Drying Coir Pith – India

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Marionbarie

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Fruit Drying – China

(54)

Chicken Barns – Quebec

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Manure Drying – Quebec

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Kreher’s

– Buffalo, NY

_{– Buffalo, NY}

(57)

NASA – Edwards, CA

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Summary

•

• Five solar dryers successfully installedFive solar dryers successfully installed •

• High value crops provided initial marketHigh value crops provided initial market •

• Significant day time solar energySignificant day time solar energy savings realized

savings realized

•

• USDA and other agricultural agenciesUSDA and other agricultural agencies need to disseminate solar drying

need to disseminate solar drying

information

•

• ICAT demonstration assistance vital toICAT demonstration assistance vital to the success of this project

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For more information on solar air

heating, please contact:

Conserval Engineering, Inc

www.solarwall.com

Email: jhollick@solarwall.com

The California Air Resources Board

www.arb.ca.gov

Email: schurch@arb.ca.gov

International Energy Agency (task 29)

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Please email your questions and

comments to: