Falling film flow characteristics of the direct absorption receiver

Technical Report · Sat Mar 01 04:00:00 EST 1986

OSTI ID:5964891

Newell, T A; Wang, K Y; Copeland, R J

This report examines the characteristics of a thin, falling film used in a direct absorption receiver, investigates the system performance, and discusses the flow similarities between water and salt. In this receiver concentrated radiation is directly absorbed within a thin layer of molten carbonate salt flowing down a near vertical wall. System capacities of 25 to 360 MW/sub t/ were analyzed. The experiments were isothermal; therefore, heat transfer characteristics were determined from film shear stress. A 25 MW/sub t/ receiver at a high turn-down ratio (5:1) marginally violates a film breakdown criterion. At high film flow rates gas and liquid interactions can cause a droplet removal phenomenon. Neither of these should affect film flow stability. Film thickness is also important in predicting operating characteristics. A rough wall surface significantly enhances wall-to-film heat transfer, but the roughness height should not exceed what the film's thickness would be over a smooth surface. In general, a molten carbonate salt film should be stable over the anticipated range of receiver capacities and operating conditions. Only small systems at low flow conditions may be near a critical opration limit.

• Research Organization: Solar Energy Research Inst., Golden, CO (USA)
• DOE Contract Number: AC02-83CH10093
• OSTI ID: 5964891
• Report Number(s): SERI/TR-252-2641; ON: DE86004432
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140702* -- Solar Thermal Power Systems-- Central Receiver
CAVITY RECEIVERS
DIMENSIONS
ENERGY TRANSFER
EQUIPMENT
FILM FLOW
FLOW MODELS
FLOW RATE
FLUID FLOW
HEAT TRANSFER
MATHEMATICAL MODELS
MOLTEN SALTS
PERFORMANCE TESTING
ROUGHNESS
SALTS
SOLAR ABSORBERS
SOLAR EQUIPMENT
SOLAR RECEIVERS
SURFACE PROPERTIES
TESTING
THICKNESS
VERY HIGH TEMPERATURE