characterising the solar resource with a temporal direct normal...

Characterising the Solar Resource with a Temporal Direct Normal Irradiance

Topograph

Preyen Perumall, Jean Pitot and Mike BrooksGroup for Solar Energy Thermodynamics (GSET)

Mechanical EngineeringUniversity of KwaZulu-Natal

2nd Annual STERG SolarPACES SymposiumStellenbosch University

July 2014

GSET © 20141

Overview:

1. Solar furnaces

2. GSET solar furnace requirements

3. Assembling solar measurement data

4. Temporal Direct Normal Irradiance Topograph (TDT)

5. Applications of the TDT

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014Group for Solar Energy Thermodynamics 2

GSET © 2014

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

• Solar furnaces concentrate solar energy to deliver high thermal fluxes onto a target area

• Harness direct normal irradiance (DNI)

• High temperature materials testing, evaluating CSP receiver technology, photochemistry experiments and solar fuels

Paul Scherrer Institute Solar Furnace

3Group for Solar Energy Thermodynamics

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

• GSET to perform CSP equipment testing

• 5-10 kW total power output requirement

• 2.5 – 3 MW/m2 peak flux

• Maintaining control over flux at the target area is a challenge

• Characterise the available solar resource for Durban

4Group for Solar Energy Thermodynamics

• Collating DNI measurements for Durban and Stellenbosch

• SAURAN data

• Visual inspection method is used to extract clear-sky days

• Interested in seasonal and daily characteristics of clear-sky days only.

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 20145Group for Solar Energy Thermodynamics

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

Durban’s TDT

Stellenbosch’s TDT

DN

I(W

/m2)

Superimposed TDT

6Group for Solar Energy Thermodynamics

Stellenbosch

Durban

• Comparing the TDT to less complex radiative model approximations of DNI

• Cross-section analyses of the TDT to setup an operational envelope

• TDT as an input to optical model of the solar furnace

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

DN

I(W

/m2)

7Group for Solar Energy Thermodynamics

Durban TDT

(Measured)

ASHRAE

Hottel

Fu Rich

Kumar

𝐷𝑁𝐼 = 𝐸0. 𝑇𝑏𝑚𝑓

Bulk atmospheric transmittance

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

Durban

8:00AM

Stell.

8:00AM

Durban

10:00AM

Stell.

10:00AM

8Group for Solar Energy Thermodynamics

January December

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

Durban

Day 20

Stell

Day 20

Durban

Day 175

Stell

Day 175

9Group for Solar Energy Thermodynamics

Future Work

• Expanding total number of clear-sky days used in generating the TDT.

• Improve the clear-sky detection method.

Conclusion

• The TDT is a time-based, empirically derived map of DNI with a high temporal resolution of 1 minute.

• Aid in the design and site suitability analyses for installation of CSP technologies.

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 201410Group for Solar Energy Thermodynamics

Characterising the Solar Resource with a Temporal Direct Normal Irradiance Topograph

GSET © 2014

Acknowledgments

• Eskom Tertiary Education Support Programme (TESP)

• Stellenbosch University – Solar Thermal Energy Research

Group (STERG)

• National Research Foundation (NRF)

11Group for Solar Energy Thermodynamics