Akki Final Rene

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NAME-AKSHAT TIWARI REG. NO-17BME0300

PERFORMANCE TEST ON SOLAR AIR DRIER

Aim To conduct the performance test of solar air dryer without fins under forced air circulation mode and plot the characteristics curves.

Apparatus required

1.Digital Thermometer 2.Digital Anemometer 3.Air Blower 4.Vegetables for drying 5.pyranometer.

About chambers of solar drier A solar air dryer is generally used for drying vegetables. It consists of two main parts namely :solar air heater drying chamber.

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Solar dryers:-

About Solar Air Heater This is used to heat the incoming air from outside. The dimensions of the solar collector is 107 x 40 x 30 cm, having a GI sheet at the bottom of collector painted completely black and used as an absorbent surface in order to exert the heat transfer area were the sides are aluminium painted in order to reflect the sun rays to the blackened surface. This is covered by 4-mm thick glass plate at the top. One end of the collector was fixed to the drying chamber while the other end is connected to an air blower for forced convection. Angle of inclination of air collector is 17o.

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Drying Chamber This is used to dry the product, which is placed in the tray. The dimensions of the drying chamber was 30 x 60 cm, having free provisions for the wooden tray to fix on the drying chamber at different height along the height of the drying chamber. The product, which is to be dried, is kept on the different trays provided on drying chamber. The hot air, which is from the solar air heater, passes through the drying chamber, this hot air is used for drying products.

Procedure 1) Cut the vegetables into small slices and weigh them (each minimum of 40 gms) and distribute equally all the four trays. 2) Place the trays into drying chamber after spreading all vegetables. 3) Switch on the air blower and kept it in a constant air flow rate. 4) Note all the temperatures from different places using digital thermometer. 5) Measure the solar flux using pyranometer. 6) Repeat the readings for a time interval of 30 min.

Formulae 1. Estimate the performance of the solar air heater: Mass flow rate of air, = A * V, kg/s

Where,

Density of air = P/RT Where,

P = Atmospheric Pressure (101.325 kN/m2 ) R = Gas constant(0.2865 kJ/kgK)

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T = Atmospheric temperature (315K)

Pyranometer reading*1000 (w/m*m) Solar flux, Ig = Sensitivity of pyranometer Where,

Pyranometer Reading

(µV)

Sensitivity of pyranometer

9.98 (µV/W/m2)

efficiency = m Cpa (T0-Ti)/Ig*Ac Where, Cpa = Specific heat of air =

1.005 kJ/kgK

Ac = Flat plate collector (top surface) area

0.5537(m2)

Where, Ac = Lc* Wc Lc = Length of top surface of collector

1.13 (m)

Wc = Width of top surface of collector

0.49 (m)

2. Estimation of the percentage of moisture content removed on wet basis (Mwet):

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M(wet)=w-d/w *100

(%)

and on dry basis, M(dry)=w-d/d*100

(%)

Where,

Observation:

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W – Weight of material when wet

------------- (kg)

d – Weight of material when dry

------------- (kg)

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Percentage of moisture content removed on wet basis

Percentage of moisture content removed on dry basis

Tray 1 %

Tray 2 %

Tray 3 Tray 4 % %

Tray 1 %

Tray 2 %

Tray 3 %

Tray 4 %

10.25

11.75

1.5

2.2

11.4

13.3

1.5

28.2

6.9

7.6

11.1

9.2

7.4

8.28

12.5

10.2

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Observation:

m

Initial mass of the vegetables in Trays (gm) S.No.

1.

T inlet Toutlet ( oC) (oC)

Time

4:20

38

43.2

Tambient (oC) 58

Tray 1 (gm)

40

Tray 2 Tray 3 (gm) (gm)

Tray 4 (gm)

40

31.1

40

Results and discussions

Percentage of moisture content removed on wet basis

m

Percentage of moisture content removed on dry basis

Tray 1 %

Tray 2 %

Tray 3 Tray 4 % %

Tray 1 %

Tray 2 %

Tray 3 %

Tray 4 %

10.25

11.75

1.5

11.4

13.3

1.5

28.2

2.2

Final Tray (gm)

35.9