Thermophysical Properties of a Cryogenic Pulsating Heat Pipe

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Lukas Feierabend M.S. Graduate StudentMechanical
Engineering
Thesis Model Development and Simulation of
Central Receiver Systems for Solar Towers
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Model Development and Simulation of Central
Receiver Systems for Solar Towers
L. Feierabend, S.A. Klein, D.T. Reindl
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• Technology Overview

Process flow diagram of the PS10 solar tower
power plant. 1

• The heliostat field, evenly distributed on the
  northern hemicycle (PS10) around the tower,
  tracks the position of the sun and reflects
  radiation onto the central receiver.

• Heat transfer fluid (HTF) (e.g. molten salt,
  steam, air) flows through tubes on the receiver
  surface and absorbs incident solar radiation.

• Thermal energy is stored in large units to
  compensate for times when there is little or no
  solar radiation and during peak loads.

• The HTF is routed into a heat exchanger to
  deliver heat for a steam cycle (Rankine, Brayton).

• This cycle converts thermal energy into
  electricity with a nominal output of 11 MW (PS10).

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Cylindrical Receiver

• Heat transfer fluid tubes are welded together to
  form a cylindrical surface area.

• Solar radiation is incident on the entire
  receiver circumference, therefore the heliostat
  field can be extended to cover the ground area
  completely around the tower. However, one has to
  consider that

• the costs for the heliostat field account for
  about a third of the total investment costs.

• Additionally, the radiation flux incident from
  the southern part of the field is low compared to
  the radiation reflected from the northern mirrors.

Cylindrical receiver on top of the Solar Two
Power Tower in Barstow, CA. 2

• The cylinder surface is completely exposed to the
  surroundings, thus the convective and radiative
  heat losses are high.

Cavity Receiver

• The receiver cavity is formed by welded tubes,
  which contain the heat transfer fluid. The
  receiver face approximates a semicircular
  cylinder shape.

• Reflected radiation enters the cavity through a
  north-facing aperture. The heliostat field is
  built exclusively within the range of possible
  incidence angles onto the receiver.

• The geometry of the cavity-type receiver reduces
  radiative and convective heat losses, although
  forced convection losses depend significantly on
  the wind direction.

PS10 cavity-type receiver . 3
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• Project Objectives

• Improvement of existing correlations for
  convective heat losses from receiver surfaces
  with numerical modeling of air flow around
  different receiver geometries.
• Development of a TRNSYS model for cavity-type
  central solar receivers for future incorporation
  into the Solar Analysis Model.

References 1 Romero, M., Buck, R. and Pacheco
J. E. (2002). An Update on Solar Central Receiver
Systems, Projects, and Technologies, Journal of
Solar Energy Engineering, Vol. 124, pg.
98-108. 2 http//renewablefeed.googlepages.com/s
olarpower 3 http//www.worldfutureenergysummit.c
om/files/geyer_michael.pdf