Anti-heat source fluctuation heat exchange system based on active flow regulation and control method thereof

Abstract

An anti-heat source fluctuation heat exchange system based on active flow control and its controlling method are provided. In operation, the heat source is delivered to both the tube side and the shell side of two sub-heat exchangers through two distinct processes, where it exchanges heat with the working fluid. An electronic control unit monitors the heat source flow fluctuations in the main circuit using flow sensors. Based on this data, the control unit adjusts the position of an electronic control three-way valve and continuously monitors the heat source flow rate in the sub-circuit in real time. This allows precise control of the flow distribution ratio of the heat source across the sub-circuits, ensuring that the heat exchange system maintains the required heat transfer to the working fluid despite fluctuations in the heat source flow. The system demonstrates a high level of adaptability to fluctuations in heat source.

1 . An anti-heat source fluctuation heat exchange system based on active flow control, comprising: a heat source circuit, a working fluid circuit, a control circuit, a first sub heat exchanger, a second sub heat exchanger, and an electronic control unit,
 wherein the heat source circuit comprises a main heat source circuit, a first sub heat source circuit, and a second sub heat source circuit; the first sub heat source circuit is connected to the first sub heat exchanger, and the second sub heat source circuit is connected to the second sub heat exchanger; the main heat source circuit is equipped with a first heat source flow sensor and a first heat source temperature sensor, the first sub heat source circuit is equipped with a second heat source flow sensor and a second heat source temperature sensor, and the second sub heat source circuit is equipped with a third heat source flow sensor and a third heat source temperature sensor; the working fluid circuit comprises a main working fluid circuit, a first sub working fluid circuit, a second sub working fluid circuit, a working fluid collection circuit; the first sub working fluid circuit is connected to the first sub heat exchanger, and the second sub working fluid circuit is connected to the second sub heat exchanger; the main working fluid circuit is equipped with a first working fluid flow sensor and a first working fluid temperature sensor, the first sub working fluid circuit is equipped with a second working fluid flow sensor, and the second sub working fluid circuit is equipped with a third working fluid flow sensor; the main heat source circuit, the first sub heat source circuit, and the second sub heat source circuit are connected through a heat source electronic control three-way valve, and the main working fluid circuit, the first sub working fluid circuit, and the second sub working fluid circuit are connected through a working fluid electronic control three-way valve; the electronic control unit is respectively connected to the heat source electronic control three-way valve, the second heat source flow sensor, and the third heat source flow sensor; the first sub heat exchanger is the same as the second sub heat exchanger, but heat exchange coefficients of heat source fluid in the first sub heat exchanger and the second sub heat exchanger are different; the first sub heat exchanger and the second sub heat exchanger are a combination of shell-and-tube exchangers; the heat source is located on a shell side of the first sub heat exchanger and flows around working fluid in the outer tube side, while the heat source is located on a tube side of the second sub heat exchanger and flows around the working fluid in the shell side.   
     
     
         2 . A control method for an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 1 , comprising:
 S1, during an operation of the system, the heat source is introduced into the first sub heat source circuit and the second sub heat source circuit through the main heat source circuit; the first heat source flow sensor and the first heat source temperature sensor respectively measure the flow and temperature of the main heat source circuit; the second heat source flow sensor and the second heat source temperature sensor respectively measure the flow and temperature of the first sub heat source circuit; and the third heat source flow sensor and the third heat source temperature sensor respectively measure the flow and temperature of the second sub heat source circuit;   S2, the electronic control unit operates the heat source electronic control three-way valve based on the flow signal provided by the first heat source flow sensor, the electronic control unit monitors and adjusts a flow rate of the first sub heat source circuit in real time based on the flow signal from the second heat source flow sensor, and the electronic control unit monitors and adjusts a flow rate of the second sub heat source circuit in real time based on the flow signal collected by the third heat source flow sensor, so that the heat source from the main heat source circuit to be controllably distributed between the first sub heat source circuit and the second sub heat source circuit in any flow ratio;   S3, the working fluid is introduced into the first sub working fluid circuit and the second sub working fluid circuit through the main working fluid circuit, the first working fluid flow sensor and the first working fluid temperature sensor respectively measure the flow and temperature of the main working fluid circuit, the second working fluid flow sensor collects a flow signal of the first sub working fluid circuit, and the third working fluid flow sensor collects a flow signal of the second sub working fluid circuit;   S4, when there is a fluctuation in the heat source, the electronic control unit adjusts the heat source electronic control three-way valve based on the flow signal provided by the first heat source flow sensor, the electronic control unit monitors and regulates the flow rate mh,1 of the first sub heat source circuit in real time based on the flow signal received from the second heat source flow sensor, the electronic control unit monitors and regulates the flow rate mh,2 of the second sub heat source circuit in real time based on the flow signal from the third heat source flow sensor, the system calculates a constant total heat exchange quality Qz and a total flow rate mh,z required by the working fluid, and specific values of the flow ratio mh,1/mh,2 of the heat source fluid are determined and controlled in real-time by the following equation system:   
       
         
           
             
               
                 
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         in the formula, m h,i , m c,i  are respectively the mass flow rates at the inlets of the sub heat source circuits and the sub working fluid circuits, kg/s; Q is the heat exchange capacity, J; U i  is the heat exchange coefficient, W/(m 2 K); ε i  is the heat exchange efficiency; T h,in  and T c,in  are respectively the inlet temperature and the outlet temperature of the heat source, K; A is the heat exchange area, m 2 ; c p,h  and c p,c  are the constant pressure specific heat of the heat source and the constant pressure specific heat of the working fluid, KJ/(kg·K); D h,i  and D c,i  are the density of the heat source and the density of the working fluid, respectively, kg/m 3 ; μ h  and μ c  are the dynamic viscosity of the heat source and the dynamic viscosity of the working fluid, Pa·s; and pr h  and pr c  are the Prandtl number of the heat source and the Prandtl number of the working fluid. 
       
     
     
         3 . The control method for a heat exchange system with an anti-heat source fluctuation heat exchange system according to  claim 2 , wherein in S3, the working fluid is introduced into the working fluid collection circuit after completing heat exchange with the heat source in both the first and second sub-heat exchangers, maintaining the constant total heat exchange quality from the heat source to the working fluid at a constant value, effectively mitigating the negative impact of heat source fluctuations on the heat exchange. 
     
     
         4 . The control method for an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 2 , wherein the working fluid in S3 is introduced into the first and second sub heat exchangers at the same inlet flow ratio, thereby achieving anti-heat source fluctuation without the need to adjust the working fluid flow ratio. 
     
     
         5 . The control method for an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 2 , wherein the working fluid in S3 is introduced into the first and second sub heat exchangers at different flow ratios to achieve stable heat exchange output over a broader range of heat source fluctuations. 
     
     
         6 . The control method for a heat exchange system with an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 2 , wherein the flow areas and the flow resistances of the heat source in the two sub heat exchangers are different; when the heat source is stable, the inlet flow distribution ratio of the sub heat exchanger with a larger heat source flow area is increased to allow more heat source to exchange heat with the working fluid, effectively reducing the flow resistance on the heat source side while maintaining constant heat exchange. 
     
     
         7 . The control method for an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 2 , wherein the heat source is located in the shell side of the first sub heat exchanger and undergoes countercurrent heat exchange with the working fluid in the tube side, and the heat source is located in the tube side of the second sub heat exchanger and undergoes countercurrent heat exchange with the working fluid in the shell side. 
     
     
         8 . The control method for an anti-heat source fluctuation heat exchange system based on active flow control according to  claim 2 , wherein when there is heat source fluctuation, the inlet flow distribution ratio of the heat source between the first sub heat source circuit and the second sub heat source circuit is adjusted to maintain a constant total heat exchange quality from the heat source to the working fluid unchanged; when the heat source is stable, the inlet flow distribution ratio of the heat source in the first sub heat source circuit and the second sub heat source circuit is adjusted to effectively reduce the flow resistance of the heat source, while maintaining constant heat exchange.