Measuring system for critical heat flux density in horizontal pipe and regulation and control method

Abstract

The invention discloses a measuring system for critical heat flux density in a horizontal pipe and a regulation and control method. The measuring system comprises a refrigerant liquid storage tank, an electric fan, a heating sheet, a circulation pipeline, a ball valve switch, a frequency converter, a gear pump, a mass flow meter, a preheating section, a data acquisition module, an industrial computer, an experiment section, a T-shaped thermocouple, a communication line, a pressure sensor, a visual transparent pipe, a high-speed camera, a refrigerant inlet pipeline, a U-shaped condenser, a cooling water inlet pipeline, a cooling water outlet pipeline, a refrigerant outlet pipeline, a water tank, an electromagnetic expansion valve, a liquid nitrogen tank, a water pump and a plastic water bottle. The measuring system has the advantages of being simple in system, reliable in judgment condition and high in measuring precision when used for monitoring and measuring the critical heat flux density phenomenon in the low-heat-flux and low-mass-flow-rate horizontal pipe. The regulation and control method has the advantages of being easy and convenient to operate and good in system stability.

Description

technical field [0001] The invention belongs to the technical field of general thermal equipment, and in particular relates to a critical heat flux measurement system and control method in a horizontal tube. Background technique [0002] The heat transfer coefficient of boiling heat transfer in horizontal tubes is usually several times higher than that of single-phase heat transfer, which has energy-saving benefits and is closely related to power, aerospace, low-temperature refrigeration and other fields, but critical heat flux will appear in boiling heat transfer in horizontal tubes. The critical heat flux is a thermal parameter that must be strictly monitored on the boiling heat transfer surface. For various heat exchange equipment that operates with controlled heat flux in the process of heat transfer and conversion, once the heat flux exceeds the critical heat flux value, it will cause The heat transfer coefficient drops rapidly, and the wall temperature rises sharply, w...

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Problems solved by technology

The critical heat flux is a thermal parameter that must be strictly monitored on the boiling heat transfer surface. For various heat exchange equipment that operates with controlled heat flux in the process of heat transfer and conversion, once the heat flux exceeds the critical heat flux value, it will cause The heat transfer coefficient drops rapidly, and the wall temperature rises sharply, which may cause equipment burnout

Aiming at the problem of continuous instability of boiling heat transfer in horizontal tubes, how to reduce and suppress the degree of system instability; in view of the problem that most of the critical heat flux determination conditions in horizontal tubes are determined from qualitative concepts, that is, under the condition of controlled heat flow, the heating wall is extremely A small increase in heat flux will result in a large increase in wall temperature

How to define the quantitative determination conditions for the critical heat flux density in the horizontal tube under low heat flux and low flow rate; when the critical heat flux occurs in the system, the pressure in the experimental section will be greatly reduced and the flow rate will fluctuate. If the system pressure and flow rate fluctuations cannot be stabilized in time, it will be Cause the measured heat flux value to be inaccurate

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