Hello everyone,

 

I am an Engineering student currently working on a project. The project is to design and fabricate CSP (concentrated solar power) based vapor absorption refrigeration system. I hope everyone here knows about vapor absorption system and its components.

 

The problem that led me to post here is that, I am using concentrated solar power from a parabolic trough as a heat source for my generator. The generator is actually a pipe which contains the refrigerent and absorbent solution(LiBr-Water),the generator is directly exposed to the concentrated solar light. Now I am all set with other components of the system, the only problem is:

 

"I have T1 as temperature at pipe(generator) inlet and T2 as the temperature at exit and the 'Qg' is the heat transfer per second to the pipe through radiation, now how can I calculate the length of the pipe so that I get T2 as my exit temperature".

 

It is easy to find the length of the pipe for me if the heat transfer is between two fluids but here as the source is solar light, so I am confused what I should do now?

 

Thanks in advancs.

The way you put it its a simple energy balance. Troughs have an efficiency of about 70%, the maximum irradiation you can expect is 940 W/m2, but use maybe 700 W/m2 as a design point.

The problem is however much more complex. The reflected light will illuminate the receiver tube unevenly. The energy distribution on the tube depends on the troughs rim angle and the precision (shape, tracking, torsion). This will cause the receiver tube to bend and move out of focus or worse brake the glass tube. The flow of thermal fluid through the receiver must be high enough as to cool adequate the walls and prevent bowing.

In 2014 at the Solarpaces conference in Beijing Prof. M.H.Abedine-Sanigi from the Shiraz University in Iran presented a paper: "Analysis of Thermal Stress of Absorber Tube of a Parabolic Collector ....."

You can contact me at : juhaven@huiyin-group.com My company produces receivers for parabolic troughs

 

I wish you good luck

Thanks juha for the help.

But the thing is that, The average temperature of my generator would be around 102^oC and I am not using glass tube only one tube(metallic) will work out and I am going to optimize the trough for max possible performance.