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 (430°F, 221°C), considerable energy could be used to maintain such temperatures during nightly shutdown 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.

1.
Bergan, N. E., 1986, “Testing of the Molten Salt Electric Experiment Solar Central Receiver in an External Configuration,” Sandia National Laboratories report SAND86-8010, Oct.
2.
Boyer, H. E., and Gail, T. L., eds., 1985, Metals Handbook Desk Edition, American Society for Metals.
3.
Burr, A. H., 1982, Mechanical Analysis and Design, Elsevier, New York.
4.
Cheung
F. B.
, and
Baker
L.
,
1976
, “
Transient Freezing of Liquids in Tube Flow
,”
Nuclear Science and Engineering
, Vol.
60
, pp.
1
9
.
5.
Goodier, J. N., 1937, “Thermal Stress,” ASME Journal of Applied Mechanics, Vol. 4.
6.
Incorpera, F. P., and De Witt, D. P., 1985, Fundamentals of Heat and Mass Transfer, 2nd ed., John Wiley and Sons, New York, pp. 181–191.
7.
Mujumdar, A. S., and Mashelkar, R. A., eds., 1984, Advances in Transport Processes, Vol. III, Wiley Eastern Limited, pp. 35–117.
8.
Young, W. C, 1989, Roark’s Formulas for Stress and Strain, 6th ed; McGraw-Hill, New York, pp. 722–724.
This content is only available via PDF.
You do not currently have access to this content.