Solar Air HeaterSydney LynnCole Tinsley

Introduction● Solar air heating is a solar thermal

technology in which the energy from the

sun is isolated and captured by an

absorbing medium and used to heat air

● Goal: Test free vs forced internal

convection of solar air heater and heat

produced

Introduction

● Use of black paint

increased emissivity to

0.98

● Graphite increased

surface area

● Maximizing efficiency

Materials● Pyranometer

● Anemometer

● Thermometer

● Battery powered fan

● HOBO

Methods: 10 Steps1. System: Air Heater

2. Geometry: Flat Plate

3. Direction: x

4. Energy flows: Convection

5. Boundary Conditions: Convection at

surface,Constant Surface Temperature

6. Internal Conditions: no qdot

7. Constant k: yes

8. Transient

9.

Results: Free Convection

Results: Forced Convection

Data Analysis: Stella

Figure 1:Temperature Increase from Inlet to Outlet

Over Time for Forced Convection [K,s]

Figure 2:Stella for Forced Convection

Results● hfree = 5.6 W/m2*K

● hforced = 4.2 W/m2*K

○ Laminar Flow

● q” = 753.4 W/m2

● q = 758.5 W

Conclusion- Free Convection: ΔT = 31℃

- Forced Convection: ΔT = 17℃

- Free Convection: η = 58%

- Forced Convection: η = 47%

- The Solar Air Heater produced

warmer air under free

convection!

Appendix: Important Variables Surface Area of black graphite = 1.0068 m2

Cross Sectional Area of Heating Area = 0.0406

m2

Cp air = 1005 J/kg*K

ρ air = 1.225 kg/m3

Average Internal Air Velocity = 1.85 m/s

αs = 0.98

ε = 0.98

Solar Irradiance (G) = 820 W/m2

Appendix: Hand Calculations

Pt. 1

Appendix: Hand Calculations

Pt. 2

Appendix: Hand Calculations

Pt. 3

Appendix: Stella

References● “Sustainable Shed Solar Air Heater” Presentation. Entire BE 4730 Class

Prepared by: Carolyn Coffey, Ben Leppard, and Matt Rosen.

● BE 4120 Class Notes. Dr. Caye Drapcho