Name: PRACHI PAHARIYA

Id no.: 14AG63R10

Native place: KATNI (M.P.)

Email:prachipaharia28@gmail.com

Education: B.TECH(AGRICULTURAL ENGG.)

University of graduation: CAE, JAWAHARLAL NEHRU

KRISHI VISHWAVIDYALAYA, JABALPUR (M.P.)

Year of passing out: 2014

Job experience (if any): NO

Training/projects undergone: TRAINING-1. ONE MONTH FROM CENTRAL REGION FARM MACHINERY TRAINING AND TESTING INSTITUTE , BUDNI(M.P.),

2. ONE MONTH TRAINING IN FOOD PROCESSING FROM CIAE, BHOPAL (M.P.).

3. FOUR MONTH TRAINING IN REMOTE SENSING FROM IIRS, DEHRADUN(U.K.)

Project :DESIGN OF RPEC DRYER UNDER GUIDANCE OF PROF. C.M. ABROAL.

Seminar on: AERATION SYSTEM FOR STORAGE.

This seminar helps us to understand the topic deeply and way of presenting .It also improves the confidence. The teachers are very helpful and guide the student on their mistake and want to improve the student. This seminar the proper knowledge how to present.

AERATION SYSTEM FOR STORAGE

PRESENTEDBY

PRACHI PAHARIYA(14AG63R10)

FOOD PROCESS ENGINEERING

AGRICULTURAL AND FOOD ENGINEERING DEPARTMENTINDIAN INSTITUTE OF TECHNOLOGY

KHARAGPUR

CONTENT

INTRODUCTIONMOISTURE MIGRATIONPURPOSE OF AERATION SYSTEMAIR MOVEMENTWHY AERATEHOW AERATION WORKEXPERIMENTAL SETUPDESIGN CONSIDERATION BASIC COMPONENTSAERATION-DRYING OR COOLINGREFERENCES

Aeration is the process of moving air through stored grain at low flow rates to maintain its quality.

It is a well known and proven Integrated Pest Management (IPM) tool for controlling insects and other risks in stored grains. Useful storage management tool which can preserve grain from deterioration, especially where the moisture content of the grain is above its safe level.

INTRODUCTION

MOISTURE MIGRATION

PURPOSE OF AERATION SYSTEM

Aeration of stored grain has four main purposes —

Preventing mould

Inhibiting insect development

Maintaining seed viability

Reducing grain moisture

Air movement within the grain stack

Grain at the top of the stack is the hottest, as heat rises through the grain. The sun heats the silo roof and internal head space, resulting in the surface grain at the top of the silo heating up .

When grain is stored at moisture contents above 12 percent, the air in the head space heats and cools each day creating ideal conditions for condensation to form, wetting the grain at the top of the stack.

From the aeration fan outlet, air will take the easiest route to the top of the grain stack — the path of least resistance.

Poor aeration ducting can result in pockets of grain not being aerated.

The peak of grain in a silo is another common place that aeration bypasses. The path of least resistance is to the side, below the peak of the stack as it is a shorter distance from the aeration ducting.

WHY AERATE

DRY GRAIN

To remove generated heat and water from grain

It keep the grain in temperature equilibrium with the outside thereby preventing moisture migration

Important in reducing mold growth and insect activity.

Fumigant applicant

Removing or reducing odors from grains.

WET GRAIN

Removes heat by natural respiration of the grain and keep the grain near to the outside air temperature

Number of days grain can be held under various condition without excessive spoilage and deterioration

Properties of grain samplesThe grains were maintained at a moisture content of 11 -13%. Impurities were reduced to less than 2%.

The following grain properties were analysed regularly to monitor the changes happening during storage of grains in the silos.

1. 100 seeds weight (kg)2. Moisture content (d.b)3. Grain density (kg/m3)4. Bulk density (kg/m3)5. Bed porosity

EXPERIMENTAL SETUP

Other suggested chemical properties

1. Pasting properties (Farinograph and RVA)2. Cooking properties (Texture, hardness)3. Lipid content4. Protein content5. Phenols6. Flavour

CALCULATING CYCLE TIME:

Where, AT = aeration time, hours/cycleAR = airflow rate, cfm/buTW = test weight, lb/bu1 lb/bu=12.87 kg/m3

Controlled aeration at 15oC in early autumn and 7oC in late autumn for 2-cycle. Binning in summer followed by controlled aeration at 24oC (2 cycle autumn cooling cycle)

General design factors

•Location/harvest date

•Grain Type (coarse vs. small)

•Storage structure

•Available energy

•Cooling speed vs. energy cost

DESIGN CONSIDERATIONS

• Airflow rate

• Propeller vs. centrifugal fan type

• Airflow direction (suction or pressure)

• Distribution (ducts or perforated floor)

• Control (manual or automatic)

Other factors to be considered:

Basic components of the aeration system

• Fans

• Ducts

• Floor distribution system

• Roof vents, exhaust fans

• Controls for fan regulation

• Pressure switch on fans for negative pressure systems

Axial

– Van-axial

– Tube-axial (small - 2Hp or less)

– Low cost, noisy

– 3 – 5 inches static pressure

Fans

Centrifugal

– 1460 to 3500 rpm

– Higher cost

– Quieter

– More airflow per HP above 5” static pressure

Available Aerations Systems

1. A single perforated duct.

2.A rectangular perforated area located in the middle of the floor.

3. A cross duct arrangement.

4. A V shaped duct

5. A fully perforated floor.

Vent types

1. Gooseneck vent

2. Mushroom vent

3.Roof exhauster

OPIGIMAC Temperature and Insect Monitoring, Aeration Fan Control System

Roof vents controllers• Normally closed• Designed to open under pressure of vacuum• Interlocked electrically with fans• Reduces insect infiltration Fan controllers• Temperature limit thermostats• Humidity control• NEMA 4R housing• Hour meter, selector switch• Time delay relays (TDR) for multiple fans• Off-the-shelf components Relative humidity and temperature controllers

Air distribution systems

Provide uniform airflow through the grain.

Consist of

– Transitions, manifolds, supply ducts– Perforated ducts, pads or false floors– Roof vents or exhaust fan systems

Transition/supply duct air velocities

• Maximum design air velocity

– positive pressure: 2500 fpm– negative pressure: 2000 fpm

• Preferred design air velocity

– positive pressure: 1500-2000 fpm– negative pressure: 1000-1500 fpm

Depends on the fan motor (upper limit of air flow).Negative Airflow– Pros…• Reduced condensation under steel roofs.• Cooling zone movement estimated by fan exhaust air temperatures.• Can hold covers on outdoor grain piles.– Cons…• Needs larger transition/duct cross-section areas (especially in flat storage).• Roof damage if vents freeze (use neg. pressure switch).•Top grain heat moves through all grain.

Air flow rates

Positive Airflow– Pros…• Distribution in flat storage is more uniform• Add warm grain w/o heating cool grain• Aeration zone finished when surface grain cools• Less plugging of perforated floors or ducts– Cons…• Condensation under steel roofs• Heat of compression raises air temp. 3-10° F

Air flow path ratio

A + B <= 1.5 CC: duct to grain peakA + B … longest path

Perforated floorsCereal Grains: 3/32”diameter perf.Smaller Seeds: 3/64 to 1/16”

Grain aeration systems are generally designed to carry out either a drying or cooling function — not both.

•Aeration cooling can be achieved with airflow rates of 2–3 litres per second per tonne delivered from fans driven by a 0.37 kilowatt (0.5 horsepower) electric motor.

• Aeration drying can be achieved with fans delivering 15–25L/s/t, typically powered by 7kW (10hp) electric motors.

• The risk of using high capacity fans for cooling is they increase grain moisture very quickly if run when ambient conditions are above 85 per cent relative humidity.

Cooling or drying — making a choice

There are some simple rules to follow:

• Grain that is dry enough to meet specifications for sale (12.5 per cent for wheat or 13.5 per cent for sorghum) can be cooled, without drying, to slow insect development and maintain quality during storage.

• Grain of moderate moisture (up to 15 per cent for wheat and sorghum) will require aeration drying to reduce the moisture content to maintain quality during storage.

• If aeration drying is not available immediately, moderately moist grain can be cooled for a short period to slow mould and insect development, then dried when the right equipment is available.

•High-moisture grain (for example, 16 per cent and higher for wheat and sorghum) will require immediate moisture reduction before cooling for maintenance.

Reed, C. R. 2006. Aeration. In: Managing Stored Grain to Preserve Quality and Value. AACC International, St. Paul, Newyork, Pages 141-180Navarro, S. and R. Noyes. 2002a. (Eds.) The Mechanics and Physics of Modern Grain Aeration Management. CRCPress, Boca Raton, FL 647 pp.O.H. Friesen, D.N. Huminicki.1986. Grain Aeration and Unheated Air Drying , Manitoba Agriculture , pages 3-30. Chris Warrick, Kondinin Group, July 2011. Aerating Stored Grain Cooling or Drying For Quality Control. GRDC, pages 2-20

REFERENCES

THANK YOU