Device for Improving the Efficiency of Rankine Cycle of Non-azeotropic Working Fluid Using Secondary Flow Mechanism

Abstract

The invention discloses a device capable of adopting a secondary flow mechanism and improving the non-azeotropic working medium Rankine cycle efficiency. The device comprises a steam generator, an expansion mechanism, an electric generator, a condenser, a liquid accumulator, a working medium pump, a preheater and a control mechanism. The device solves the heat transfer deterioration problem generated in the evaporation heat transfer process of non-azeotropic mixed working media, and heating of high-pressure side working medium fluid is divided into two steps carried out by the preheater and an evaporator, and a plate type heat exchanger with the small resistance loss and high heat exchange coefficients is adopted by the preheater and is used for removing supercooling of the working media. The optimized-design secondary flow mechanism is adopted by the evaporator, the disturbance and mixing action is introduced, the heat transfer mass transfer resistance added by the non-azeotropic working media is overcome, and the cycle efficiency is improved. The device is widely applied to efficient utilization of medium and low temperature heat energy, the medium and low temperature heat energy can be efficiently converted into mechanical energy and electric energy, and waste heat utilization of renewable energy sources is promoted.

Description

technical field [0001] The invention relates to the field of high-efficiency utilization of medium and low temperature heat energy, in particular to a device for improving the efficiency of a non-azeotropic working medium Rankine cycle by adopting a secondary flow mechanism. Background technique [0002] With the increasing shortage of renewable energy, the development and utilization of new energy is becoming increasingly important. The organic Rankine cycle power generation that uses medium and low temperature solar energy, geothermal energy, biomass energy and waste heat in industrial production as driving heat energy is the solution to this problem. One of the effective ways to solve a problem. But at present, the actual power generation efficiency of the organic Rankine cycle system studied at home and abroad is not very high, and its energy loss mainly comes from the expander and heat exchanger. For a certain fixed expander, its irreversible loss depends not only on i...

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Problems solved by technology

On the other hand, due to the increase of the proportion of high boiling point components on the surface of the liquid film, the temperature of the gas-liquid interface increases, and there is a temperature difference between the surface of the liquid film and the gas layer, so that part of the incoming heat will be consumed in the gas layer Sensible heat for additional heat transfer resistance

Therefore, the heat transfer of non-azeotropic mixtures will deteriorate due to the increase of mass transfer and heat transfer resistance in the process of evaporation and heat transfer.

Similarly, in the condenser, when the mixed working fluid releases heat at the wall surface, the high boiling point working medium tends to condense first, and forms a liquid boundary layer film, which hinders the condensation of low boiling point gases, resulting in the increase of mass and heat transfer resistance at the interface. heat transfer deterioration

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