Experimental system for researching heat transfer characteristics of cold energy power generation wound tube type heat exchanger

Abstract

The invention relates to an experimental system for researching heat transfer characteristics of a cold energy power generation coiled tube heat exchanger. Comprising a working medium storage tank, a first pump with a feeding port communicated with a discharging port 1a of the working medium storage tank, a liquid nitrogen heat exchanger with a first feeding port 3a communicated with a discharging port of the first pump and a condenser with a first feeding port 4a communicated with a first discharging port 3b of the liquid nitrogen heat exchanger, and a first discharging port 4b of the condenser is communicated with a feeding port 1b of the working medium storage tank. The liquid nitrogen heat exchanger is a coiled tube type heat exchanger. By adopting the technical scheme of the invention, the method can be used for researching the phase change heat transfer process of shell pass evaporation and condensation, accurately obtaining the phase change heat transfer rule of the working medium in the coiled tube type heat exchanger, and exploring the factors of the coiled tube type heat exchanger influencing the heat transfer coefficient and the pressure drop and the distribution rule of shell pass phase change flow; the feasibility research of the coiled tube type heat exchanger in LNG cold energy power generation is realized, and the blank that the coiled tube type heat exchanger is used as a condenser in an LNG cold energy power generation device in the prior art is filled.

Description

Technical Field

[0001] The present invention relates to the technical field of coiled-tube heat exchangers for cold energy power generation, and in particular to an experimental system for studying the heat transfer characteristics of coiled-tube heat exchangers for cold energy power generation. Background Art

[0002] Liquefied natural gas (LNG) contains a large amount of cold energy. Applying it to thermal cycle power generation will help improve energy utilization in industrial production and promote energy conservation and emission reduction.

[0003] The use of Rankine cycle to achieve LNG cold energy power generation is currently the mainstream cold energy utilization method with high comprehensive benefits. The performance of the condenser (heat exchange device used for heat exchange between LNG and circulating working fluid) in the circulation system directly affects the efficiency of the entire circulation system. In view of the characteristics of low temperature, high pressure and large flow of LNG in cold energy power generation devices, the coiled tube heat exchanger is very suitable for use as a condenser in LNG cold energy power generation devices due to its wide range of applications, high compactness, and simultaneous heat exchange of multiple streams. In the condenser, the low-temperature and high-pressure LNG flows along the tube side and vaporizes, and the circulating medium used for expansion power generation flows along the shell side and condenses on the outer wall of the heat exchange tube.

[0004] Up to now, there are few research results or related reports on the use of coiled heat exchangers as condensers in LNG cold energy power generation devices, and there are no cases of them being put into use. Therefore, the heat transfer effect, influencing factors, and design and calculation methods of coiled heat exchangers under relevant working conditions need further experimental research and verification. Summary of the invention

[0005] The present invention provides an experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation, which can realize the feasibility study of the coiled heat exchanger in LNG cold energy power generation and fill the gap in the prior art of using the coiled heat exchanger as a condenser in an LNG cold energy power generation device.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] An experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation, comprising a working fluid storage tank for storing working fluid, a No. 1 pump whose feed port is connected to an outlet port 1a of the working fluid storage tank, a liquid nitrogen heat exchanger whose No. 1 feed port 3a is connected to an outlet port of the No. 1 pump, and a condenser whose No. 1 feed port 4a is connected to an outlet port 3b of the liquid nitrogen heat exchanger, wherein the No. 1 outlet port 4b of the condenser is connected to the feed port 1b of the working fluid storage tank, and the liquid nitrogen heat exchanger is a coiled heat exchanger.

[0008] The beneficial effects of the present invention are as follows: the working fluid discharged from the working fluid storage tank is pressurized by pump No. 1, first enters the liquid nitrogen heat exchanger to exchange heat with liquid nitrogen, and then enters the condenser tube after cooling down, providing cooling capacity and heating for the condensation process outside the tube, and finally returns to the working fluid storage tank. By utilizing the circulation of the working fluid, the heat exchange performance of the circulating working fluid in the liquid nitrogen heat exchanger is achieved, thereby proving the feasibility of the coiled tube heat exchanger in LNG cold energy power generation.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the No. 1 discharge port 4b of the condenser is connected to a No. 1 control valve, the feed port of the No. 1 control valve is connected to the No. 1 discharge port 4b of the condenser, and the discharge port is connected to the feed port 1b of the working fluid storage tank.

[0011] The beneficial effect of adopting the above further solution is: the flow rate of the working fluid introduced from the condenser to the working fluid storage tank can be controlled by the No. 1 control valve to ensure sufficient heat exchange.

[0012] Furthermore, the discharge port of the No. 1 pump is connected to a No. 1 bypass valve, the feed port of the No. 1 bypass valve is connected to the discharge port of the No. 1 pump, and the discharge port is connected to the feed port of the No. 1 pump.

[0013] The beneficial effect of adopting the above further scheme is: when bypass valve No. 1 is opened, the fluid output by pump No. 1 will not continue to flow to the subsequent part of the system, but will directly flow back to the feed port of pump No. 1 through bypass valve No. 1, forming a cycle; in some cases, such as when the system pressure is too high or emergency shutdown is required, opening bypass valve No. 1 can quickly reduce the system pressure and protect other equipment and pipelines in the system from damage; and the outlet flow of pump No. 1 can be controlled by adjusting the opening of bypass valve No. 1.

[0014] Furthermore, the discharge port 1a of the working fluid storage tank is also connected to pump No. 2, the feed port of pump No. 2 is connected to the discharge port 1a of the working fluid storage tank, the discharge port is connected to the vaporizer, the No. 1 feed port 6a of the vaporizer is connected to the discharge port of pump No. 2, the No. 1 discharge port 6b is connected to the No. 2 feed port 4c of the condenser, and the No. 2 discharge port 4d of the condenser is connected to the feed port 1b of the working fluid storage tank.

[0015] The beneficial effect of adopting the above further scheme is that the working fluid discharged from the working fluid storage tank is pressurized by the No. 2 pump, enters the vaporizer to exchange heat with the circulating water to increase the temperature, and is completely vaporized, and then enters the condenser to exchange heat with the working fluid at the outlet of the liquid nitrogen heat exchanger, is condensed into liquid, and is returned to the working fluid storage tank together with the working fluid after the heat exchange.

[0016] Furthermore, the No. 2 outlet port 4d of the condenser is connected to a No. 2 control valve, the feed port of the No. 2 control valve is connected to the No. 2 outlet port 4d of the condenser, and the outlet port is connected to the feed port of the working fluid storage tank.

[0017] The beneficial effect of adopting the above further solution is: the flow rate of the working fluid introduced from the condenser to the working fluid storage tank can be controlled by the No. 2 control valve to ensure sufficient heat exchange.

[0018] Furthermore, the discharge port of the No. 2 pump is connected to a No. 2 bypass valve, the feed port of the No. 2 bypass valve is connected to the discharge port of the No. 2 pump, and the discharge port is connected to the feed port of the No. 2 pump.

[0019] The beneficial effect of adopting the above further scheme is: when the No. 2 bypass valve is opened, the fluid output by the No. 2 pump will not continue to flow to the subsequent part of the system, but will directly flow back to the feed port of the No. 2 pump through the No. 2 bypass valve, forming a cycle; in some cases, such as when the system pressure is too high or an emergency shutdown is required, opening the No. 2 bypass valve can quickly reduce the system pressure and protect other equipment and pipelines in the system from damage; and the outlet flow of the No. 2 pump can be controlled by adjusting the opening of the No. 2 bypass valve.

[0020] Furthermore, the No. 2 discharge port 6d of the gasifier is connected to a heating water tank, the feed port of the heating water tank is connected to the No. 2 discharge port 6d of the gasifier, and the discharge port is connected to the No. 2 feed port 6c of the gasifier.

[0021] The beneficial effect of adopting the above further scheme is that the gasifier and the heating water tank form a circulating water branch, which can provide a heat source for the gasifier, and the circulating water circulates between the gasifier and the heating water tank.

[0022] Furthermore, the discharge port of the heating water tank is connected to a water pump, the feed port of the water pump is connected to the discharge port of the heating water tank, and the discharge port is connected to the No. 2 feed port 6c of the gasifier.

[0023] The beneficial effect of adopting the above further solution is: to achieve the circulation of water through the water pump and to control the circulating water flow rate through the water pump.

[0024] Furthermore, the experimental system also includes a liquid nitrogen storage tank for storing liquid nitrogen, the discharge port of the liquid nitrogen storage tank is connected to the second feed port 3c of the liquid nitrogen heat exchanger, and the second discharge port 3d of the liquid nitrogen heat exchanger is used to discharge nitrogen.

[0025] The beneficial effect of adopting the above further scheme is that the liquid nitrogen storage tank and the liquid nitrogen heat exchanger form a cooling branch to cool the working medium to the temperature required for the test. After the liquid nitrogen is discharged from the liquid nitrogen storage tank, it is gasified into nitrogen in the liquid nitrogen heat exchanger and directly discharged outdoors.

[0026] Furthermore, the exhaust port 1c of the working fluid storage tank is connected to a safety valve, and the feed port of the safety valve is connected to the exhaust port 1c of the safety valve.

[0027] The beneficial effect of adopting the above further scheme is: when the working fluid is discharged from the working fluid storage tank and the tank is cleaned, the flow rate is controlled by the safety valve; when the pressure in the working fluid storage tank is too high or the working fluid needs to be discharged urgently to prevent system damage, the safety valve can be used as an emergency discharge device to quickly release the pressure or fluid, thereby protecting the safety of the entire system and regulating the system pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A structural roadmap of an experimental system for studying the heat transfer characteristics of a coiled-tube heat exchanger for cold energy power generation according to the present invention;

[0029] Figure 2 A cold circuit diagram of an experimental system for studying the heat transfer characteristics of a cold energy power generation coiled tube heat exchanger of the present invention;

[0030] Figure 3 A gas path diagram for studying the heat transfer characteristics of the cold energy power generation coiled tube heat exchanger of the present invention;

[0031] Figure 4 A circulating water branch route map for studying the heat transfer characteristics of the cold energy power generation coiled tube heat exchanger of the present invention;

[0032] Figure 5 A liquid nitrogen cooling branch route map for studying the heat transfer characteristics of the cold energy power generation coiled tube heat exchanger of the present invention;

[0033] Figure 6 This is a graph showing the variation of the shell side heat transfer coefficient and the friction pressure drop per unit length at different mass flow rates.

[0034] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0035] 1. Working fluid storage tank; 11. Safety valve; 2. Pump No. 1; 21. Bypass valve No. 1; 22. Flow meter No. 1; 3. Liquid nitrogen heat exchanger; 4. Condenser; 41. Control valve No. 1; 42. Control valve No. 2; 5. Pump No. 2; 51. Bypass valve No. 2; 52. Flow meter No. 2; 6. Vaporizer; 7. Heating water tank; 71. Water pump; 8. Liquid nitrogen storage tank. DETAILED DESCRIPTION

[0036] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0037] Example 1

[0038] like Figure 1 and Figure 2An experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation includes a working fluid storage tank 1 for storing working fluid, a No. 1 pump 2 whose feed port is connected to the discharge port 1a of the working fluid storage tank 1, a liquid nitrogen heat exchanger 3 whose No. 1 feed port 3a is connected to the discharge port of the No. 1 pump 2, and a condenser 4 whose No. 1 feed port 4a is connected to the No. 1 discharge port 3b of the liquid nitrogen heat exchanger 3, and the No. 1 discharge port 4b of the condenser 4 is connected to the feed port 1b of the working fluid storage tank 1, and the liquid nitrogen heat exchanger 3 is a coiled heat exchanger.

[0039] The beneficial effects of this embodiment are as follows: the working fluid discharged from the working fluid storage tank 1 is pressurized by the No. 1 pump 2, first enters the liquid nitrogen heat exchanger 3 to exchange heat with liquid nitrogen, and then enters the condenser 4 tube pass after cooling down to provide cooling capacity and increase the temperature for the condensation process outside the tube, and finally returns to the working fluid storage tank 1. By utilizing the circulation of the working fluid, the heat exchange performance of the circulating working fluid in the liquid nitrogen heat exchanger 3 is achieved, thereby proving the feasibility of the coiled-tube heat exchanger in LNG cold energy power generation and filling the gap in the prior art of the coiled-tube heat exchanger used as a condenser in an LNG cold energy power generation device.

[0040] The working fluid stored in the working fluid storage tank 1 may be an organic working fluid, such as Freon, propane, etc. The first pump 2 may be a gear pump.

[0041] In the embodiment of the present invention, the working fluid storage tank 1, the first pump 2, the liquid nitrogen heat exchanger 3 and the condenser 4 form a cold circuit to achieve heat exchange through the transmission of the working fluid. The working fluid enters the liquid nitrogen heat exchanger 3 to exchange heat with liquid nitrogen. After the working fluid cools down, it enters the condenser 4 tube pass to provide coldness for the condensation process outside the tube and increase the temperature, and finally returns to the working fluid storage tank 1. During the test, the data changes of the liquid nitrogen heat exchanger 3 are recorded at all times.

[0042] Through this cold circuit, the feasibility and key influencing factors of the application of coiled heat exchanger in LNG cold energy power generation process are explored; the heat transfer pressure drop and other characteristics of the working fluid in the shell-side phase change heat transfer of the coiled heat exchanger are studied; the correctness of the numerical simulation method is verified, and a certain reference is provided for the design and manufacturing method of the coiled heat exchanger under this working condition, so as to further promote the application of coiled heat exchanger in cold energy power generation.

[0043] Based on the above embodiment, a first flow meter 22 is provided on the pipeline connecting the discharge port of the first pump 2 to the first feed port 3a of the liquid nitrogen heat exchanger 3 to constantly monitor the flow rate of the working fluid derived from the discharge port of the first pump 2. In the figure, the first flow meter 22 is represented by FI.

[0044] In addition, a temperature transmitter TI and a pressure transmitter PI (not marked in the figure) are provided on the pipeline where the No. 1 flow meter 22 is provided, on the pipeline where the No. 1 outlet port 3b of the liquid nitrogen heat exchanger 3 is connected to the No. 1 feed port 4a of the condenser 4, and on the pipeline where the No. 1 outlet port 4b of the condenser 4 is connected to the feed port 1b of the working fluid storage tank 1, so that the working fluid transmission temperature can be monitored by the temperature transmitter TI, and the working fluid transmission pipeline pressure can be monitored by the pressure transmitter PI.

[0045] In this embodiment, the liquid nitrogen heat exchanger 3 and the condenser 4 are both well-known equipment to those skilled in the art, and are both coil-wound heat exchangers that can be purchased and installed from the market.

[0046] Example 2

[0047] like Figure 1 and Figure 2 On the basis of Example 1, the No. 1 discharge port 4b of the condenser 4 is connected to the No. 1 control valve 41, the feed port of the No. 1 control valve 41 is connected to the No. 1 discharge port 4b of the condenser 4, and the discharge port is connected to the feed port 1b of the working fluid storage tank 1.

[0048] The beneficial effect of adopting the preferred solution in the above embodiment is that the flow rate of the working fluid introduced from the condenser 4 into the working fluid storage tank 1 can be controlled by the No. 1 control valve 41 to ensure sufficient heat exchange.

[0049] It should be noted that the temperature transmitter TI and the pressure transmitter PI arranged on the pipeline connecting the No. 1 outlet port 4b of the condenser 4 to the feed port 1b of the working fluid storage tank 1 are arranged in front of the feed port of the No. 1 control valve 41 to perform preliminary monitoring of the transmission temperature and pipeline pressure of the working fluid entering the No. 1 control valve 41, respectively.

[0050] Example 3

[0051] like Figure 1 and Figure 2 On the basis of Examples 1 and 2, the discharge port of pump No. 1 2 is connected to bypass valve No. 1 21 , the feed port of bypass valve No. 1 21 is connected to the discharge port of pump No. 1 2 , and the discharge port is connected to the feed port of pump No. 1 2 .

[0052] The beneficial effect of adopting the preferred scheme in the above embodiment is that when bypass valve No. 1 21 is opened, the fluid output by pump No. 1 2 will not continue to flow to the subsequent part of the system, but will directly flow back to the feed port of pump No. 1 2 through bypass valve No. 1 21 to form a cycle; in some cases, such as when the system pressure is too high or an emergency shutdown is required, opening bypass valve No. 1 21 can quickly reduce the system pressure and protect other equipment and pipelines in the system from damage; and the outlet flow of pump No. 1 2 can be controlled by adjusting the opening of bypass valve No. 1 21.

[0053] It should be noted that the pipeline with the No. 1 bypass valve 21 and the pipeline provided with the No. 1 flow meter 22, the temperature transmitter TI and the pressure transmitter PI are two branches and do not affect each other.

[0054] Example 4

[0055] like Figure 1 and Figure 3 On the basis of Examples 1-3, the discharge port 1a of the working fluid storage tank 1 is also connected to the No. 2 pump 5, the feed port of the No. 2 pump 5 is connected to the discharge port 1a of the working fluid storage tank 1, the discharge port is connected to the vaporizer 6, the No. 1 feed port 6a of the vaporizer 6 is connected to the discharge port of the No. 2 pump 5, the No. 1 discharge port 6b is connected to the No. 2 feed port 4c of the condenser 4, and the No. 2 discharge port 4d of the condenser 4 is connected to the feed port 1b of the working fluid storage tank 1.

[0056] The beneficial effect of adopting the preferred scheme in the above embodiment is that the working fluid discharged from the working fluid storage tank 1 is pressurized by the No. 2 pump 5, enters the vaporizer 6 to exchange heat with the circulating water for temperature increase, and is completely vaporized, and then enters the condenser 4 to exchange heat with the working fluid at the outlet of the liquid nitrogen heat exchanger 3, is condensed into a liquid state, and is returned to the working fluid storage tank 1 together with the working fluid after the heat exchange.

[0057] In this embodiment, the working fluid storage tank 1, the second pump 5, the vaporizer 6 and the condenser 4 constitute a gas circuit to achieve heat exchange through the transmission of the working fluid. The working fluid enters the vaporizer 6 to exchange heat with the circulating water to increase its temperature, and is completely vaporized, and then enters the condenser 4 to exchange heat with the working fluid at the outlet of the liquid nitrogen heat exchanger 3.

[0058] In this embodiment, the vaporizer 6 is a device well known to those skilled in the art, and is a coiled-tube heat exchanger that can be purchased and installed from the market.

[0059] Among them, the second pump 5 can be a gear pump.

[0060] In the embodiment of the present invention, a second flow meter 52 is provided on the pipeline connecting the discharge port of the second pump 5 to the first feed port 6a of the gasifier 6 to constantly monitor the flow rate of the working medium derived from the discharge port of the second pump 5. In the figure, the second flow meter 52 is also indicated as FI.

[0061] In addition, a temperature transmitter TI and a pressure transmitter PI (not marked in the figure) are provided on the pipeline where the No. 2 flow meter 52 is provided, on the pipeline connecting the No. 1 outlet port 6b of the vaporizer 6 to the No. 2 feed port 4c of the condenser 4, and on the pipeline connecting the No. 2 outlet port 4d of the condenser 4 to the feed port 1b of the working fluid storage tank 1, so as to monitor the working fluid transmission temperature through the temperature transmitter TI and monitor the working fluid transmission pipeline pressure through the pressure transmitter PI.

[0062] It should be noted that the No. 1 discharge port 4b and the No. 2 discharge port 4d of the condenser 4 are respectively connected to a three-way valve (not shown in the figure) through a branch, and the outlet of the three-way valve is simultaneously connected to the feed port 1b of the working fluid storage tank 1. In addition, a temperature transmitter TI and a pressure transmitter PI are respectively provided on the two branches, so as to monitor the temperature and pressure of the working fluids discharged from the No. 1 discharge port 4b and the No. 2 discharge port 4d of the condenser 4 respectively.

[0063] Based on the above embodiment, a temperature transmitter TI and a pressure transmitter PI are also provided on the pipeline connecting the outlet of the three-way valve to the feed port 1b of the working fluid storage tank 1. The temperature transmitter TI and the pressure transmitter PI form a main valve to monitor the temperature and pressure of the working fluid entering the working fluid storage tank 1 at the same time.

[0064] Example 5

[0065] like Figure 1 and Figure 3 On the basis of Examples 1-4, the No. 2 outlet port 4d of the condenser 4 is connected to the No. 2 control valve 42, the feed port of the No. 2 control valve 42 is connected to the No. 2 outlet port 4d of the condenser 4, and the outlet port is connected to the feed port of the working fluid storage tank 1.

[0066] The beneficial effect of adopting the preferred solution in the above embodiment is that the flow rate of the working fluid introduced into the working fluid storage tank 1 from the condenser 4 can be controlled by the second control valve 42 to ensure sufficient heat exchange.

[0067] It should be noted that the No. 2 control valve 42 is arranged on the branch pipeline connecting the No. 2 outlet 4d of the condenser 4 to the three-way valve to accurately control the flow rate of the working fluid discharged from the No. 2 outlet 4d of the condenser 4.

[0068] Example 6

[0069] like Figure 1 and Figure 2 On the basis of Examples 1-5, the discharge port of the No. 2 pump 5 is connected to the No. 2 bypass valve 51, the feed port of the No. 2 bypass valve 51 is connected to the discharge port of the No. 2 pump 5, and the discharge port is connected to the feed port of the No. 2 pump 5.

[0070] The beneficial effect of adopting the preferred scheme in the above embodiment is that when the No. 2 bypass valve 51 is opened, the fluid output by the No. 2 pump 5 will not continue to flow to the subsequent part of the system, but will directly flow back to the feed port of the No. 2 pump 5 through the No. 2 bypass valve 51 to form a cycle; in some cases, such as when the system pressure is too high or an emergency shutdown is required, opening the No. 2 bypass valve 51 can quickly reduce the system pressure and protect other equipment and pipelines in the system from damage; and the outlet flow of the No. 2 pump 5 can be controlled by adjusting the opening of the No. 2 bypass valve 51.

[0071] It should be noted that the pipeline with the second bypass valve 51 and the pipeline provided with the second flow meter 52, the temperature transmitter TI and the pressure transmitter PI are two branches and do not affect each other.

[0072] Example 7

[0073] like Figure 1 and Figure 4 On the basis of Examples 1-6, the No. 2 discharge port 6d of the gasifier 6 is connected to the heating water tank 7, the feed port of the heating water tank 7 is connected to the No. 2 discharge port 6d of the gasifier 6, and the discharge port is connected to the No. 2 feed port 6c of the gasifier 6.

[0074] The beneficial effect of adopting the preferred solution in the above embodiment is that the gasifier 6 and the heating water tank 7 form a circulating water branch, which can provide a heat source for the gasifier 6, and the circulating water circulates between the gasifier 6 and the heating water tank 7.

[0075] Based on the above embodiment, a temperature transmitter TI is provided on the pipeline connecting the No. 2 discharge port 6d of the gasifier 6 to the heating water tank 7, and on the pipeline connecting the No. 2 feed port 6c of the heating water tank 7 to the gasifier 6, so that the temperature of the circulating water discharged from the gasifier 6 and introduced into the gasifier 6 can be monitored respectively by the two temperature transmitters TI.

[0076] Example 8

[0077] like Figure 1 and Figure 4 On the basis of Examples 1-7, the discharge port of the heating water tank 7 is connected to a water pump 71, the feed port of the water pump 71 is connected to the discharge port of the heating water tank 7, and the discharge port is connected to the No. 2 feed port 6c of the gasifier 6.

[0078] The beneficial effect of adopting the preferred solution in the above embodiment is that the circulation of water can be achieved through the water pump 71, and the circulating water flow rate can be controlled by the water pump 71.

[0079] In this embodiment, the vaporizer 6, the heating water tank 7 and the water pump 71 form a circulating water branch.

[0080] It should be noted that the temperature transmitter TI close to the No. 2 feed port 6 c of the gasifier 6 is located on the pipeline where the discharge port of the water pump 71 is connected to the No. 2 feed port 6 c of the gasifier 6 .

[0081] Example 9

[0082] like Figure 1 and Figure 5 On the basis of Examples 1-8, the experimental system further includes a liquid nitrogen storage tank 8 for storing liquid nitrogen, the discharge port of the liquid nitrogen storage tank 8 is connected to the No. 2 feed port 3c of the liquid nitrogen heat exchanger 3, and the No. 2 discharge port 3d of the liquid nitrogen heat exchanger 3 is used to discharge nitrogen.

[0083] The beneficial effect of adopting the preferred scheme in the above embodiment is that the liquid nitrogen storage tank 8 and the liquid nitrogen heat exchanger 3 form a liquid nitrogen cooling branch to cool the working medium to the temperature required for the test. After the liquid nitrogen is discharged from the liquid nitrogen storage tank 8, it is gasified into nitrogen in the liquid nitrogen heat exchanger 3 and directly discharged to the outside.

[0084] It should be noted that a temperature transmitter TI, a pressure transmitter PI and a flow transmitter FI are provided on the pipeline connecting the outlet of the liquid nitrogen storage tank 8 to the No. 2 feed port 3c of the liquid nitrogen heat exchanger 3, so as to monitor the temperature, delivery pressure and flow rate of the liquid nitrogen entering the liquid nitrogen heat exchanger 3 respectively through the temperature transmitter TI, the pressure transmitter PI and the flow transmitter FI.

[0085] Example 10

[0086] like Figure 1 On the basis of Example 1-9, the exhaust port 1c of the working fluid storage tank 1 is connected to the safety valve 11, and the feed port of the safety valve 11 is connected to the exhaust port 1c of the safety valve 11.

[0087] The beneficial effect of adopting the preferred scheme in the above embodiment is that when the working fluid is discharged from the working fluid storage tank 1 and the tank cleaning operation is performed, the flow rate is controlled by the safety valve 11; when the pressure in the working fluid storage tank 1 is too high or the working fluid needs to be discharged urgently to prevent system damage, the safety valve 11 can be used as an emergency discharge device to quickly release the pressure or fluid, thereby protecting the safety of the entire system and regulating the system pressure.

[0088] On the basis of the above-mentioned embodiments, the experimental system for studying the heat transfer characteristics of the cold energy power generation coiled tube heat exchanger described in the present invention also includes an electronic control instrument and a PLC acquisition system to monitor and automatically record more accurate test data, and to obtain timely feedback and influence of the adjustment parameters on the test. The test process can more intuitively reflect which parameter has a greater impact.

[0089] In order to study the influence of mass flow rate on the coiled heat exchanger in the LNG cold energy power generation process, the main focus is on its influence on the heat transfer effect on the shell side of the condenser. The mass flow rate on the shell side, that is, the mass flow rate of condenser 4c-4d, is changed. The speed of pump 5 is changed to adjust different mass flow rates. During the experiment, other variables are kept the same. Here, the pressure is selected as 1.35Mpa. The same experimental method is used to measure different mass flow rates. The experimental data are analyzed and calculated to obtain the heat transfer coefficient and unit length friction pressure drop on the shell side of the condenser. As shown in Table 1 below.

[0090] Table 1 Data of heat transfer coefficient and friction pressure drop per unit length on the shell side at different mass flow rates

[0091]

[0092]

[0093] At the same time, by Figure 6 It can be seen that with the increase of mass flow rate, the heat transfer coefficient on the shell side increases basically linearly. This is because the increase in mass flow rate greatly increases the degree of turbulence, making the heat exchange more sufficient and enhancing the convective heat transfer; but the friction pressure drop per unit length on the shell side also increases. The mass flow rate increases, while the cooling capacity on the tube side remains unchanged, so the condensation phase change process gradually slows down, and the mixing and surging phenomenon between the gas-liquid two-phase flow decreases, but this also increases the pressure drop, so the rate of increase slows down, but as the mass flow rate continues to increase, the influence of flow velocity occupies the main factor, which increases the friction pressure drop.

[0094] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0095] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0096] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0097] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0098] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0099] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An experimental system for studying the heat transfer characteristics of a coiled tube heat exchanger for cold energy power generation, characterized in that: The invention comprises a working fluid storage tank (1) for storing working fluid, a No. 1 pump (2) whose feed port is connected to a discharge port 1a of the working fluid storage tank (1), a liquid nitrogen heat exchanger (3) whose No. 1 feed port 3a is connected to a discharge port of the No. 1 pump (2), and a condenser (4) whose No. 1 feed port 4a is connected to a No. 1 discharge port 3b of the liquid nitrogen heat exchanger (3), wherein the No. 1 discharge port 4b of the condenser (4) is connected to the feed port 1b of the working fluid storage tank (1), and the liquid nitrogen heat exchanger (3) is a coiled heat exchanger.

2. According to claim 1, an experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation, characterized in that: The No. 1 discharge port 4b of the condenser (4) is connected to the No. 1 control valve (41), the feed port of the No. 1 control valve (41) is connected to the No. 1 discharge port 4b of the condenser (4), and the discharge port is connected to the feed port 1b of the working fluid storage tank (1).

3. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 1 is characterized in that: The discharge port of the No. 1 pump (2) is connected to the No. 1 bypass valve (21), the feed port of the No. 1 bypass valve (21) is connected to the discharge port of the No. 1 pump (2), and the discharge port is connected to the feed port of the No. 1 pump (2).

4. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 1 is characterized in that: The discharge port 1a of the working fluid storage tank (1) is also connected to the No. 2 pump (5), the feed port of the No. 2 pump (5) is connected to the discharge port 1a of the working fluid storage tank (1), the discharge port is connected to the vaporizer (6), the No. 1 feed port 6a of the vaporizer (6) is connected to the discharge port of the No. 2 pump (5), the No. 1 discharge port 6b is connected to the No. 2 feed port 4c of the condenser (4), and the No. 2 discharge port 4d of the condenser (4) is connected to the feed port 1b of the working fluid storage tank (1).

5. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 4 is characterized in that: The No. 2 outlet port 4d of the condenser (4) is connected to a No. 2 control valve (42), the feed port of the No. 2 control valve (42) is connected to the No. 2 outlet port 4d of the condenser (4), and the outlet port is connected to the feed port of the working fluid storage tank (1).

6. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 4 is characterized in that: The discharge port of the No. 2 pump (5) is connected to the No. 2 bypass valve (51), the feed port of the No. 2 bypass valve (51) is connected to the discharge port of the No. 2 pump (5), and the discharge port is connected to the feed port of the No. 2 pump (5).

7. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 4 is characterized in that: The No. 2 discharge port 6d of the gasifier (6) is connected to a heating water tank (7), the feed port of the heating water tank (7) is connected to the No. 2 discharge port 6d of the gasifier (6), and the discharge port is connected to the No. 2 feed port 6c of the gasifier (6).

8. The experimental system for studying the heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to claim 7, characterized in that: The discharge port of the heating water tank (7) is connected to a water pump (71), the feed port of the water pump (71) is connected to the discharge port of the heating water tank (7), and the discharge port is connected to the No. 2 feed port 6c of the gasifier (6).

9. An experimental system for studying heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to any one of claims 1 to 8, characterized in that: The experimental system further comprises a liquid nitrogen storage tank (8) for storing liquid nitrogen, the discharge port of the liquid nitrogen storage tank (8) being connected to the second feed port 3c of the liquid nitrogen heat exchanger (3), and the second discharge port 3d of the liquid nitrogen heat exchanger (3) being used for discharging nitrogen.

10. An experimental system for studying heat transfer characteristics of a coiled heat exchanger for cold energy power generation according to any one of claims 1 to 8, characterized in that: The exhaust port 1c of the working fluid storage tank (1) is connected to a safety valve (11), and the feed port of the safety valve (11) is connected to the exhaust port 1c of the safety valve (11).

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