DESIGN AND DEVELOPMENT OF FINNED, V GROOVE SOLAR DRYER WITH BOOSTER REFLECTOR FOR APPLICATION OF DRYING

PROCESS IN CASHEW AND FOOD INDUSTRY

PROJECT REFERENCE NO.: 38S1629

COLLEGE : SHRI MADHWA VADIRAJA INSTITUTE OF TECHNOLOGY AND

MANAGEMENT, UDUPI

BRANCH : MECHANICAL ENGINEERING

GUIDE : PROF. VIVEKANAND B HUDDAR

STUDENTS : MR. VAGISH RAO T

MR. SHETTY NINAD JAYARAJ

MR. RAYAN SWAN MENENZES

MR. RITESH MARSHEL FERNANDES

Keywords Cashew Nut, Energy Conservation, Electricity & Fuel saving, Optimization.

Introduction

Drying is the process of removing moisture content in food products .It is required to preserve them and increase their storage life. Drying, using solar radiation, is one of the oldest techniques used by mankind. It involves the application of heat to vaporize moisture and some means of removing water vapor after its separation from the food products. It is thus a combined and simultaneous heat and mass transfer operation for which energy must be supplied. There are two types of solar driers namely Direct and Indirect type solar dryers .In direct solar dryers, the material to be dried, is directly exposed to the solar radiation, placed in an enclosure, with transparent cover. In indirect solar dryer, solar radiation is not directly incident on the material to be dried, air is heated in a solar collector and then ducted to the drying chamber to dry the products.

In conventional method of cashew processing hot air is being used to dry the cashew kernels using steam and other conventional fuels like coal, kerosene and electricity. High moisture content is one of the reasons for spoilage of cashew kernels during storage & preservation. A required amount of moisture content needs to be maintained for further processing. Conventional methods of drying are though popular but have problems mentioned above. Solar dryers are the solutions for these problems. It is simple equipment that uses the potential available in the sunlight to heat the air that can be used effectively for drying.

Objectives :

Drying is one of the major processes in cashew processing industries. In conventional method it is done

in drying chamber called Borma. Borma uses heat content of steam produced in the boiler for drying

process. The objectives of the project work are

• To replace steam by solar dryer in cashew processing.

• To develop an experimental set up to find the total amount of heat supplied to drying chamber

conventionally.

• To design and develop a Solar Air Dryer based on above findings.

• To conduct an experiment of drying the cashew kernels by using developed forced convection

SAD.(Solar Air Dryer)

• To determine the moisture content removed from cashews in forced convection solar dryer.

Methodology

Following methodology is adapted to achieve the said objectives

1. Survey of cashew processing industries.

Visited nearby cashew industry named “Mahesh Cashews Pvt Ltd” Nadoor, Moodubelle,

UDUPI, and studied in detail about the cashew drying process and its favourable conditions.

Drying is one of the processes where renewable energy can be applied.

2. Design and development of a suitable solar dryer.

Developed an experimental setup to calculate the heat supplied (Q) to dry the cashew kernels

using conventional energy. Based on the findings the size of the solar air dryer was calculated.

Fig 1 : Experimental setup to calculate heat supplied (Q)

3. Experimentation of solar dryer for its performance and suitability to the process

The results obtained are used to design the solar air dryer. The designed solar air dryer was developed

and tested for drying 1 kg of cashew kernels.

Figure 2 : Solar Hot air dryer

Figure 3 : Solar hot air dryer with booster reflector

Results and Discussions

Readings taken with the solar hot dryer

Date : 19th May 2015 Place : Bantakal, Udupi Latitude (Φ) : 13.36°N Climate : Cloudy Longitude : 74.78°E Slope of the dryer (ß) : 13.25° Quantity of cashew kernels : 1000 grams Drying Chamber Type : 4 trays without guiding plates Capacity of each tray : 250grams Size : 610x175x625 mm (L x B x H) External Idle running hours : 9.30 A.M to 10.00 A.M 

Table 1: Measurement of drying air temperature, velocity, humidity and global radiation Time

in hours

Temperature - oC Velocity - m/s Voltage V in volts

TE in ºC

Humidity RH

Global radiation in W/m2 Ta

T1 T2 T3 T4 T5 T6 Inlet Outlet

10:00 30 42 37 40 41 35 38 1.3 3.0 220 32.6 62.1 623

10:30 31.5 42 37 43 42 35 39 0.7 2.4 206.5 38.9 61.8 684

11:00 33 44 38 51 47 44 39 0,7 2.1 204.8 37.4 60.1 680

11:30 33.5 47 39 50 46 45 41 0.7 2.4 205.5 37 61.4 762

12:00 33.6 47 40 53 49 48 41 0.7 2.6 204.2 35.8 59.5 738

12:30 33.6 47 40 55 53 47 45 1.3 3.2 220 34.3 57.4 726

13:00 33.3 49 40 56 52 49 46 1.3 3.3 220 36.1 55.3 749

13:30 34.3 52 41 57 54 53 49 1.3 3.2 219.6 38.1 59 713

14:00 33.7 52 42 58 54 52 50 1.1 3.3 218.5 37.3 58.9 709

14:30 33.6 51 41 57 54 53 50 1.1 3.4 217.6 37.2 60.1 649

15:00 33.6 52 41 56 54 52 50 1.3 3.5 219.3 36.4 59.6 574

15:30 33.6 49 40 54 53 52 48 1.3 3.4 220.1 36.8 61.6 493

16:00 33.2 48 40 53 52 51 48 1.3 3.1 220.7 35.8 58.4 417

Where Ta = Ambient temperature

T1 = Temperature of air in the inlet cone

T2 = Temperature of air in the outlet cone

T3= Temperature of air in the first tray

T4= Temperature of air in the second tray

T5= Temperature of air in the third tray

T6= Temperature of air in the fourth tray

TE= Exit temperature of air 

 

Table 2: Measurement of Moisture Content using Moisture Meter Sample

Number(Selected and marked)

Tray# Bottom to top

Moisture content before drying

Moisture content after drying

1 1

13.5 4.5 2 13.0 4.5 3 12.5 6.5 4 14.0 6.0 5 12.5 3.0 6

2

13.0 5.0 7 16.5 7.0 8 13.5 3.0 9 13.5 2.5 10 13.5 5.5 11

3

13.5 4.0 12 13.0 5.0 13 13.5 5.5 14 13.5 3.0 15 12.5 0.0 16

4

12.0 0.0 17 13.5 6.0 18 13.0 3.5 19 12.0 0.0 20 11.5 4.5

Figure 2 : Time V/s drying chamber outlet temperature variation

Figure 3: Variation in moisture content - before and after

0100200300400500600700800900

010203040506070

Solar R

adiatio

n W/m

2

Tempe

rature o C

Time of the day‐Hrs

Temperature Profile 

DC Temp

SHD Temp.

Solar Radiation

02468

1012141618

1 3 5 7 9 11 13 15 17 19

Moisture conten

t % 

Sample #

Moisture Content Before Drying

Moisture Content After Drying

Conclusion

The solar hot air dryer has been developed for the purpose of drying a kg of cashew kernels.

Based on the weather conditions the average temperature obtained in the dryer was 42 oC. This is just

insufficient to dry the cashew kernels. Favorable weather conditions may give the expected results. Another test is required to be conducted to come to correct conclusion.

Scope of future work

1. This design can be used for any kind of commercial crops which need drying.

2. Photovoltaic solar panel can be used to run the blower/impeller fan which makes the system to

work without electric power. .

3. Solar panel with different design can be used so that it absorbs more sunlight. For example by

using convex lens to concentrate the solar rays on the collector.

4. The wooden chamber can be modified as glass chamber/bin to achieve higher temperature.

5. Drying can be simulated using CFD (Computational Fluid Dynamics) software and the obtained

experimental results can be compared with the CFD results.