Peltier Solar Concentrator

measlyincompetentUrban and Civil

Nov 29, 2013 (3 years and 6 months ago)

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Peltier Solar Concentrator

By: Michael Forrest

Kyle Fifield

Evan White

The Problem


To demonstrate that a thermoelectric device
can efficiently converted solar energy into
electricity.


The goal is to create a system at least as
efficient as PV panels.

The Solution


Satellite Dish Solar Concentrator


Hi
-
Z HZ
-
20 Thermoelectric Module


Aluminum Collector Plate


Time
-
Based Solar Coordinate Tracking


Battery Storage


LCD User Interface



What is a Thermoelectric Device?


In a thermoelectric device, a voltage is created
when a difference in temperature exists across
the device.


By heating one side of the device and sinking
heat from the other side, an electric voltage will
be created.


Solar Rays

Solar Concentrator

Sun

Thermoelectric Device

Collector Plate

Azimuth Rotation

Horizontal

Tilt

Dc/Dc
Step
-
up

Microcontroller


Motor Controller


Motor Controller

System Diagram

Solar Tracking Subsystem


Real
-
Time Clock (DS1307)


User interface with Buttons and LCD Screen


Microcontroller (
Coldfire
)


Motor Controller (H
-
Bridge)


DC
Motor with
Potentiometer (Azimuth)


Linear Actuator with Accelerometer (Altitude)

Solar Tracking System Diagram

H
-
Bridge
Circuit

Coldfire Microcontroller

Time of Day Sensor

Potentiometer

Accelerometer

LCD Display and
User Interface

H
-
Bridge
Circuit

Motor

Linear Actuator

Solar Tracking Positioning Equations

Altitude Angle =


Azimuth Angle =

Inputs



Date and Time



Longitude and Latitude



s

cos
Microcontroller Code

Solar Rays

Solar Concentrator

Sun

Thermoelectric Device

Collector Plate

Azimuth Rotation

Horizontal

Tilt

Microcontroller


Motor Controller


Motor Controller

System Diagram

Mechanical Azimuth Tracking


Elevation

Tracking

Linear Actuator

Solar Concentrator

Highest Sun Elevation (70⁰)

Lowest Sun Elevation (12⁰)

70⁰

12⁰

6 inch Stroke

Tracking Code

Thermoelectric Collector Plate Mount


Purpose:


Maximize Performance and Power Efficiency of HZ
-
20.


HZ
-
20 Module Around 5% Efficient.


Design Aspects:


Minimum Load of 200 psi on HZ
-
20.


Thermal Expansion of HZ
-
20.


Efficient Heat Transfer


Keeping Cold Side of HZ
-
20 Cool.

Subsystem Diagram of Thermoelectric Mount

Collector Plate

Thermoelectric Device

Heat Sink

Belleville Springs

Solar Rays

Hot Side

Cool Side

Loading on HZ
-
20 Module


Ensures Module
Remains in
Compression to
Maximize Heat Transfer.


Solution:


Belleville Springs.


Apply Large Amount of
Force in Compact Area.


Also Allows for Thermal
Expansion.

Load and Thermal Expansion Calculations

Thermoelectric Device Dimensions

Load Required: 200 psi*

𝐴 𝑒𝑎
=
2
.
8𝑖

𝑥

2
.
8𝑖
=
7
.
84
𝑖
2



𝐹 𝑐𝑒
=
200𝑖

𝑥

7
.
84
𝑖
2
=

𝐿
=



𝑇


𝑥

𝐿


Where:


𝐿

= Change in Length




= Thermal Expansion*



𝑇

= Change in Temp.


𝐿
= Initial length

Force Calculation

Thermal Expansion Calculation


𝐿
=
20𝑥
10

6


1
200°𝐶
0
.
2𝑖

*Information Given from Specification Sheets

Efficient Heat Transfer


Thermal Grease:


Ensures Efficient Heat Transfer from Mount to HZ
-
20 and
HZ
-
20 to Heat Sink.



Overhang of 0.5 Inches and 0.25 Inches of Thickness
on Mount:


Ensures Uniform Heating on HZ
-
20.



Thermal Resistance Diagram

T
Bar

T
H

T
C

T
HS

T
A

∆T

Thermal Resistance
of

Thermal Adhesive

Thermal Resistance of

Thermoelectric Junction

Thermal Resistance

of

Heat
Sink

Temperature of Bar

Temperature
of Hot Side

Temperature of Cold Side

Temperature of Heat Sink

Temperature of Ambient

Energy Gain

B

A

Area
Eclipes

=
π
AB

Area of Dish = 0.303077m²

Area of FP = 0.003488m²

Energy Gain = Area of Dish / Area of Focal Point


Energy Gain =
87


Efficiency Strategies


85% Reflectivity

Dish Covered with Reflective Tape


Aluminum Collector Plate Painted Black

Absorbs 90% of light

Efficiency Diagram

Reflective Tape 85%
Efficient

Sun

90% Absorption
Efficiency

5% Heat to
Electricity Efficiency

Wasted
Heat

Step
-
up Dc/Dc


Converter

95% Efficient

12v Lead


Acid

92% Storage
Efficiency

Total Efficiency =
3.34%

Sunlight to Usable Energy

Power Diagram

1000W/m
²

303.1W

Sun

Concentrator

Collector

232W

8 mins to heat up

Thermoelectric Device

220W

Heat Sink

3V, 6.67A, 20W

Dc/Dc
Step
-
up

12V, 1.6A, 19W

Dc/Dc Step
-
up Convertor

1.8V to 5.5V

User Interface

Displays:


Time of Day


Date


Azimuth Angle


Altitude Angle


Pushbuttons:


Up/Down
Selection Arrows


Menu Option


Enter Button

Areas of Responsibility

Evan


Kyle


Mike

Solid Modeling / Thermoelectric Device Mounting / Altitude
Tracking Mechanical

Energy & Power Calculations/ Thermal Design/


Dc
-
Dc Step
-
Up Circuit/ Azimuth Tracking Mechanical / Base Design

Solar Tracking Programming/ Real Time Clock Programming/ Angle
Calculations/ LCD User Interface Programming and Design

Project Management




Budget


Item

Part Number

Store

Length/Package Quanity

Order Quanity

Price

Cold Draw 1" x 1.5" x 12"

8910K838

McMaster Carr

12"

1

$24.28

Steel Hex Head Cap Screw 3/4"
-
10 Thread 3
-

1/2" Length

91247A849

McMaster Carr

5

1

$10.45

Hex Nut 3/4"
-
10 Thread 1
-
1/4"W, 27/64"H

91015A036

McMaster Carr

5

1

$5.17

Plain Steel Type A SAE Flat Washer 3/4" Screw Size

91083A036

McMaster Carr

21

1

$3.00

Steel Flange
-
Mounted Ball Bearings

7208K51

McMaster Carr

1

1

$23.34

Setscrew Shaft Collars 3/8" Bore

9414T8

McMaster Carr

1

2

$0.72

Black
-
Oxide Coated Steel Shaft 3/8" OD

1886K12

McMaster Carr

18"

1

$11.40

Steel Timing Belt Pulley Pitch Diameter 0.637", 0.2 Pitch

6495K711

McMaster Carr

1

1

$10.54

Steel Timing Belt Pulley Pitch Diameter 3.80", 0.2 Pitch

6495K732

McMaster Carr

1

1

$38.85

Timing Belt 0.2 Pitch, 27.0" Outer Circle

1679K143

McMaster Carr

1

1

$9.82

Compact DC Gearmotor 12 VDC, 0.6 rpm

6409K11

McMaster Carr

1

1

$44.96

Setscrew Shaft Collars 3/16" Bore

9414T5

McMaster Carr

1

1

$0.62

Aluminum Metric T
-
Slotted Mounting Bracket, 40mm

5537T244

McMaster Carr

1

2

$13.46

Set
-
Screw Shaft Coupling 5/16" Bore

2424K12

McMaster Carr

1

1

$7.63

Nylon Flat Belt Idler Pulley 3/8" Bore

6235K64

McMaster Carr

1

1

$12.48

5/16" Drive Shaft

1327K72

McMaster Carr

6"

1

$6.50

TOTAL

$237.40

Questions?