Optimum design method of pipeline length of organic Rankine cycle heat exchanger considering flow pattern

Abstract

The invention discloses an optimum design method of the pipeline length of an organic Rankine cycle heat exchanger considering a flow pattern. When organic working media are in a single-phase flow state, an average Nu of one section is calculated to get heat exchange amount of the section, the heat exchange amount is compared with actual heat exchange amount, and a pipe length value of the section is determined. When the organic working media are in a two-phase flow state, a convective heat-transfer coefficient calculation method of a corresponding flow pattern is selected to obtain a convective heat-transfer coefficient of the section, heat exchange amount of the section is calculated according to the convective heat-transfer coefficient value and an assumed pipe length in the end, the heat exchange amount is compared with the actual heat exchange amount, the pipe length of each dividing section is determined, and the pipeline length of the heat exchanger can be obtained. Computational accuracy of the heat exchange amount is obviously improved through consideration of flow pattern changes of media in the process of two-phase evaporation and condensation, and the optimum design method can be applied to determination of pipeline lengths of organic Rankine cycle heat exchangers using various commonly-used fluids.

Description

technical field [0001] The invention relates to a method for optimizing the pipe length design of an organic Rankine cycle heat exchanger considering the flow pattern. technical background [0002] In 2011, my country's GDP was about 7.30 trillion US dollars, and the total primary energy consumption was 2.613 billion tons of oil equivalent. my country's GDP accounts for 10.47% of the world's total GDP, but the energy consumed for this accounted for 21.29% of the world's total energy consumption. Statistics show that my country's energy consumption per 10,000 yuan of GDP is 2.03 times that of the world average, 2.38 times that of the United States, 4.18 times that of Germany, and 4.40 times that of Japan. my country's industrial energy consumption accounts for more than 70% of the whole society's energy consumption, and high industrial energy consumption is the main reason for my country's high energy consumption per unit of GDP. However, 60% - 65% of industrial energy cons...

AI Technical Summary

Problems solved by technology

[0004] In the existing evaporator and condenser pipe length design methods, a certain empirical formula is basically selected for calculation, without considering the flow pattern in the two-phase evaporation and condensation process, resulting in low calculation accuracy of the heat exchanger pipe length

At the same time, the scope of application of the empirical formula is narrow, which is not conducive to the research, promotion and application of the organic Rankine cycle

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