Modelling solar and thermal radiation in CSP solar receiver

Gioacchino La Rochelle · November 15, 2018, 06:47

The physic I have
I have a open solar receiver to model by mean of CFX.
Up to now all models are pure convective with free surface exchange between open cavity (at temperature of about 750 °C) and outer environment.
The cavity actually has two boundaries interested into mass tranport (inlet and outlet) with the solar spot impacting on the inlet from the open roof.

The model I need
The model need to be:
- convective to analyse the amount of energy leaving the opening because of bouyancy forces
- solar radiative because of enormous incident solar radiation. This can be now assumed as a source term acting defined on the inlet energy balance
- Thermal radiative Surface-to-Surface
The impact of solar and Thermal radiation on the fluid are on the wall-heat Exchange I suppose.

Issue
I've tried to include P1 radiation model but, the source term basically altered the true mass flow fixed on the inlet because of density contribution.
So I think to skip to Monte Carlo or Discrete transfer as suggested by:
https://www.slideshare.net/Marcushuy...0-heattransfer

Question
- Using Monte-Carlo or ray-tracer how can I ensure that the two radiative models are separated because of two different optical properties on the solar and infrared band?

Opaque · November 15, 2018, 08:52

Change the Spectral Model from Gray to Multiband.

Define the spectral band of interest. Note that spectral band must cover the thermal radiation spectrum completely for the temperature range of interest, i.e. sum of the blackbody fraction of each band == 1 (@ operating temperature)

Read the documentation about the spectral model.

Use CEL expressions to define the spectral variation you intend to use.

November 15, 2018, 06:47	Modelling solar and thermal radiation in CSP solar receiver	#1
Gioacchino La Rochelle New Member Gioacchino La Rochelle Join Date: Jul 2016 Posts: 19 Rep Power: 10	The physic I have I have a open solar receiver to model by mean of CFX. Up to now all models are pure convective with free surface exchange between open cavity (at temperature of about 750 °C) and outer environment. The cavity actually has two boundaries interested into mass tranport (inlet and outlet) with the solar spot impacting on the inlet from the open roof. The model I need The model need to be: - convective to analyse the amount of energy leaving the opening because of bouyancy forces - solar radiative because of enormous incident solar radiation. This can be now assumed as a source term acting defined on the inlet energy balance - Thermal radiative Surface-to-Surface The impact of solar and Thermal radiation on the fluid are on the wall-heat Exchange I suppose. Issue I've tried to include P1 radiation model but, the source term basically altered the true mass flow fixed on the inlet because of density contribution. So I think to skip to Monte Carlo or Discrete transfer as suggested by: https://www.slideshare.net/Marcushuy...0-heattransfer Question - Using Monte-Carlo or ray-tracer how can I ensure that the two radiative models are separated because of two different optical properties on the solar and infrared band?

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November 15, 2018, 08:52		#2
Opaque Senior Member Join Date: Jun 2009 Posts: 1,880 Rep Power: 33	Change the Spectral Model from Gray to Multiband. Define the spectral band of interest. Note that spectral band must cover the thermal radiation spectrum completely for the temperature range of interest, i.e. sum of the blackbody fraction of each band == 1 (@ operating temperature) Read the documentation about the spectral model. Use CEL expressions to define the spectral variation you intend to use.