Solar power plant: steam quality questions

In summary, an engineer is working on the design of a solar power plant that will use "solar troughs" to generate steam for a turbine. The challenge is determining the length of pipe needed for the water to reach the desired temperature. The engineer is seeking suggestions and calculations for the heat transfer rate and energy required for vaporization.
  • #1
CUaero12
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0
Hey guys, I'm an engineer working on the design of a small start up solar power plant. The solar power plant will operate using "solar troughs" instead of the traditional photovoltaic cells. In these systems water is the working fluid and sunlight is focused from a solar reflector onto a pipe containing the water. Here is an image of a typical solar trough:

[PLAIN]http://www.renewableenergyaccess.com/assets/images/story/2004/3/26/SEGS_NREL.jpg

The water is pumped through a large field of these parabolic solar troughs until it is superheated steam that is suitable to run through a turbine.

Right now I'm working on the basic heat transfer problem regarding the solar collector field and have run into a bit of a roadblock.

The water will be entering the field at 110 degrees Fahrenheit and needs to exit the field at 550 degrees Fahrenheit. I'm trying to compute how long the pipe in the field needs to be to achieve this temperature. I've got most of it down except the transitional part between liquid and steam. When the water starts to boil, the temperature will remain constant until all of the fluid is vaporized. During this time the quality of the steam will change and the volume of the fluid will be composed of liquid and vapor. I'm trying to iterate through and see how much length of field it will take before the water is completely vaporized (the quality is 100%) but am having trouble figuring out how to compute this. I want to iterate through using a while loop (while the quality of the fluid is less than 100%, keep adding one meter length of pipe to the field until this is achieved) but am stuck on figuring out exactly how.

Does anyone have any ideas or insight into the problem? Let me know if more information about the problem is needed, I can provide more details and numbers if necessary (the mass flow rate through the field is known as well as the heat of vaporization, etc.)
 
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  • #2
Have you been able to figure out your heat transfer rate per unit length: Q / L ? If not, I can make some suggestions.

If so, the energy required to vaporize the water is: Qvap = mdot * hfg

where,

Qvap = heat required for vaporization
mdot = mass flow rate of water / steam
hfg = latent heat of vaporization (look up in steam tables)

Qvap = heat required for vaporization

and you can solve for length of pipe to transfer Qvap.
 

Related to Solar power plant: steam quality questions

1. What is the purpose of measuring steam quality in a solar power plant?

Steam quality is an important factor in the efficiency of a solar power plant. It refers to the amount of water vapor present in the steam used to drive the turbines. Measuring steam quality helps to ensure that the plant is operating at its optimal efficiency, and also helps to prevent damage to equipment due to excessive moisture in the steam.

2. How is steam quality measured in a solar power plant?

Steam quality is typically measured using a device called a steam quality meter, which uses a combination of pressure and temperature sensors to determine the percentage of water vapor in the steam. This information is then used to adjust the plant's operations and maintain the desired steam quality.

3. What is the ideal steam quality for a solar power plant?

The ideal steam quality for a solar power plant is around 90%. This means that 90% of the steam produced by the plant is water vapor and the remaining 10% is liquid water. This balance ensures efficient energy production while also preventing damage to equipment due to excessive moisture.

4. How does steam quality impact the overall efficiency of a solar power plant?

Steam quality has a direct impact on the overall efficiency of a solar power plant. Higher steam quality means that more energy is being produced with the same amount of steam, resulting in higher efficiency. On the other hand, lower steam quality can lead to reduced efficiency and potentially costly damage to equipment.

5. How is steam quality maintained in a solar power plant?

Steam quality can be maintained in a solar power plant through regular monitoring and adjustments to the plant's operations. This may involve adjusting the temperature and pressure of the steam, as well as making sure that the water used in the steam production process is properly treated to prevent impurities that can affect steam quality.

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