design of a food dehydrator

Doruk Angun Süleyman Anıl UğurMelis Kirevetözen

Design of an Apple Dehydrator

Contents Introductıon

Instruments

Design

Cost Analysis

Patent Search

Results

Conclusion

1.INTRODUCTION

2.INSTRUMENTS

1. AC Square Equipment Fan

2. AC Mini Heater

3. Trays (x5)

4. Cold Rolled Steel Sheet Housing

5. Thermostat

1.1.AC Square Equipment Fan Product Code: 1976K43 (mcmaster.com)

Airflow: 94cfm

Diameter: 119mm

AC: 120 volt

Frame: Aluminum

Blade: Steel

1.2. AC Mini Heater Sold on: Ebay.com

Diameter: 120 mm

Power: 600 Watt

AC: 220 Volt

1.3.Tray Manufacturer: Aeomash

Tray Size: 50*50 cm

Number of trays used: 5

Material Type: Stainless Steel

1.4.Cold Rolled Carbon Steel Sheet Housing Thickness: 0.30 mm- 2 mm

Yield Strength: 228 MPa

Tensile Strength: 331 MPa

1.5.Thermostat

Thermostat is a device that maintains the temperature in a system near a desired temperature. This device, switches the heater on and off in order to maintain the temperature.

It is desired that, the system should never exceed 40 °C, in order to prevent the apple to burn. To do that, “Luxell mini oven thermostat” is used.

DESIGN

1. Design Criteria

2. Technical Drawings

1.Design CriteriaFor this design, our aim was to build a food

dryer which has the properties as, low cost, having a small size in order to be used in a kitchen of a home, efficient (consumes less electric), and which requires less time to dry the apples.

Properties of the apple and trays, required to calculate the values in the system are given below;

Dimensions of an apple: one slice of an apple which has a half circular shape with 0.07 m diameter and 0.005 m thickness.

Number of slices in a tray: 45

Dimensions of trays: 0.05*0.05 m

Number of trays used: 5

Total number of slices: 45*5=225

Total apple mass: 9.375 apple*(229gr/apple)=2.147 kg apple

Initial water mass: One apple contains %83.93 of water which is equal to 2.147kg*(83.93)%100=1.801 kg

Total dry weight: 2.147-1.801=0.346kg

Final water mass: The apple water content is desired to %4 of the total mass X/X+0.346=0.04 x=0.01433 kg of water

Water mass desired to be evaporated: 1801 -14.34=1786.66 g

2. Technical Drawings

Cost Analysis In this project, it was aimed to build low cost

food dryer. In order to do this, low cost instruments with high quality are used.

Appropriate material for the trays with holes is found on the “alibaba.com”, which has 50 cm width and has a price of 6 US $/meter. Since 5 trays are needed and tray size is desired as 50-50 cm, its cost is calculated as 15 US $.

For the housing of the system, light material, with a high strength and a low cost is desired. Aluminum was the first idea, however due to its higher cost Cold Rolled Steel Sheet is preferred. Prices are asked from the “Gebze Makina A.Ş.”, prices in the below are given by the company;

Since, the low cost was our design criteria cold rolled steel sheet metal is chosen. According to our calculations it is found out that 15.111 kg of material is needed. So, the housing price of the system is calculated as

Aluminum sheet metal 12 TL/KG

Stainless steel sheet metal 16 TL/KG

Cold rolled steel sheet metal 5 TL/KG

INSTRUMENTS PRICES

Fan 26,94 US $

Heater 16.97 US $

Trays 15 US $

Housing 32.57 US $

Thermostat 4.31 US $

TOTAL COST 95,79 US $

PatentA patent is a right granted to the owner of an

invention that prevents others from making, using, importing or selling the invention without his permission.

Patents are a form of intellectual property

Technical drawn of our design front inside

Technical drawing of the Mike Moles patent

Mike Moles’ systemA dehydrator for improving energy efficiency and reducing

the cost and air pollution associated with drying food products, such as grapes into raisins.

The improved dehydrator utilizes the same basic structure as prior art dehydrators, which have multiple drying tunnels that each define a drying chamber in which the products are dried and a burn chamber in which a heat source heats air that is circulated to the drying chamber by a circulating fan.

The differences between Mike Moles’ system and our systemMike Moles’ system was designed for the

industry, so a lot of food was dried in this system, but our system was designed for the home and this system has dehydrated less food.

Our design has one fan and one heater and one shield .However ,Mike Moles’ system has two fan and one heater so, the Mike Moles’ design more complicated from our system.

In our system there is a one inlet which becomes the coming from the inlet and coming from the trays and there is one outlet but the Mike Moles’ design has the two different inlet source and reheated air coming from the trays.

The cost of the our system is cheaper than the Mike Moles’ system.

Energy consumption of our system is very little according to Mike Moles’ design.

RESULTS

RESULTS w1=w2 ;

w2 is assumed as 0,03 and iterations are done

Water mass balance:

m*w2+mv=m*w3

mo*wamb+m-mo*w3=m*w1

combined ;

mo*wamb+mv=mo*w3

RESULTS Energy balance

m*h1+P=m*h2

m*h2+mv*hf=m*h3

m0*hamb+m-mo*h3=m*h1

combined;

mo*hamb+P+mv*hf=mo*h3

RESULTS

Table 1. Choosing the right output mass flow rate

RESULTS

Table 2.Temperature and humidity data in the 1-2-3 regions for various flow rates

RESULTS

RESULTS

CONCLUSION

In this project, we have improved our skills about;

drawing a device in CAD software,

writing codes on MATLAB,

searching a patent

finding the right material for the design.

Thank you for listening