Wet Bulb or Dry Bulb

To whom it may concern,

I have a question regarding the evaporative cooling system design. For the power tower and trough, SAM requests inputs to design the cooling system, one very vital input is the cooling tower approach to wet bulb. The cooling system input menu asks for the "Ambient Temp At Design" but does not specify if it is the ambient wet bulb or the ambient dry bulb. Is the program using wet bulb for evaporative cooling and dry bulb for dry cooling and just not specifying on the inputs page?

Thank you,

John

Dear John,

The Help topic for the parabolic trough (physical model) Power Cycle page has explanations of both the ambient temperature at design and approach temperature input variables that I think answer your questions:

Ambient temp at design (ºC)

The ambient temperature at which the power cycle operates at its design-point-rated cycle conversion efficiency. For the air-cooled condenser option, use a dry bulb ambient temperature value. For the evaporative condenser, use the wet bulb temperature.

Approach temperature (ºC)

For the evaporative type only. The temperature difference between the circulating water at the condenser inlet and the wet bulb ambient temperature, used with the ref. condenser water dT value to determine the condenser saturation temperature and thus the turbine back pressure.

Best regards,
Paul.