Investigation of cold filling receiver panels and piping in molten-nitrate-salt central-receiver solar power plants Page: 1 of 10
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
INVESTIGATION OF COLD FILLING RECEIVER PANELS AND PIPING IN
MOLTEN-NITRATE-SALT CENTRAL-RECEIVER SOLAR POWER PLANTS
James E. Pacheco, Mark E. Ralph, and James M. Chavez
Solar Thermal Technology and Test Departments
Sandia National Laboratories
Cold filling refers to flowing a fluid through piping or tubes that
are at temperatures below the fluid's freezing point. Since the
piping and areas of the receiver in a molten-nitrate salt central-
receiver solar power plant must be electrically heated to maintain
their temperatures above the nitrate salt freezing point (4304F,
221*C), considerable energy could be used to maintain such
temperatures during nightly shut down and bad weather.
Experiments and analyses have been conducted to investigate
cold filling receiver panels and piping as a way of reducing
parasitic electrical power consumption and increasing the
availability of the plant. The two major concerns with cold filling
are: 1) how far can the molten salt penetrate cold piping before
freezing closed and 2) what thermal stresses develop during the
associated thermal shock.
Cold fill experiments were conducted by flowing molten salt at
550*F (288*C) through cold panels, manifolds, and piping to
determine the feasibility of cold filling the receiver and piping.
The transient thermal responses were measured and heat transfer
coefficients were calculated from the data. Nondimensional
analysis is presented which quantifies the thermal stresses in a
pipe or tube undergoing thermal shock. In addition, penetration
distances were calculated to determine the distance salt could
flow in cold pipes prior to freezing closed.
Bi = Biot number
Cps = specific heat of solid
Cpm = specific heat of liquid
D = diameter of pipe
E = modulus of elasticity
Fo = Fourier number
h = heat transfer coefficient
hf = heat of fusion
DISTRIBUTION OF THIS DOCUMENT IS UNLIM
k = thermal conductivity of pipe (Eq. 5)
L = wall thickness
Nu = Nusselt number
Pr = Prandtl number
r = radial coordinate of pipe
ri = inner radius of pipe
r~ = outer radius of pipe
r* = nondimensional pipe radius
R = radial coordinate of inner radius of pipe
R = radial coordinate of frozen layer
Re = Reynolds number
T = temperature
Tr = freezing point
Ti= initial wall temperature
T, = inlet liquid temperature
Tw = wall temperature
T. = fluid temperature
x*= nondimensional distance from insulated surface
z = distance to freeze closed
a = thermal diffusivity (Eq. 3) or coefficient of thermal expansion
a = thermal diffusivity of liquid
a, = thermal diffusivity of solid
S = 1 - ri = nondimensional wall thickness
a = characteristic values of transient conduction equation
y = parameter measuring the relative importance of sensible to
latent heat, assumed to be 0.7 (water)
0* = nondimensional temperature
0,* = nondimensional temperature at the insulated surface
ae = circumferential stress
ar= radial stress
a,= axial stress
a = nondimensional thermal stress
v = Poisson's ratio
James E. Pacheco, et. al.
1995 ASME International Solar Energy Conference
Lahaina, Maui, HI
March 19-24, 1995
Here’s what’s next.
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Pacheco, J. E.; Ralph, M. E. & Chavez, J. M. Investigation of cold filling receiver panels and piping in molten-nitrate-salt central-receiver solar power plants, article, December 31, 1994; Albuquerque, New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1280613/m1/1/: accessed April 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.