Single-tube test device and method for performance test of condensation-boiling double-phase-change evaporator

Abstract

The invention relates to the technical field of heat exchangers, and particularly discloses a single-tube testing device and method for performance testing of a condensation boiling double-phase-change evaporator, and the device comprises a testing body, a measuring loop connected with the testing body, a condensation loop connected with the testing body, and a cooling loop connected with the condensation loop and the measuring loop. The test body comprises a sleeve, a measuring tube and a condensing and evaporating tube which are arranged in the sleeve and have axes parallel to the sleeve, and sealing covers which are arranged at two ends of the sleeve and are used for sealing the sleeve; two ends of the measuring tube are connected with the measuring loop; the two ends of the condensation evaporation pipe are connected with the condensation loop. According to the invention, the heat transfer performance test and research of the double-phase-change evaporator under high-temperature and high-pressure conditions can be realized, and the evaporation capacity of the evaporator under different dryness degrees under the combination of different in-tube condensation and out-tube boiling pressures can be obtained.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically, to a single-tube test apparatus and method for testing the performance of a condensing-boiling two-phase change evaporator. Background Technology

[0002] Existing technologies for testing evaporator performance mainly focus on single-sided phase change (where the medium inside the tube does not change phase during external boiling) or external boiling and internal condensation under atmospheric pressure. Current research generally analyzes boiling and condensation as independent processes, with a serious lack of research and understanding on the heat coupling and mutual influence between the two processes on the same heat transfer element. In particular, there is a lack of systematic experimental data and heat transfer mechanism research on the small temperature difference two-phase change heat transfer characteristics under high pressure. Although a lot of results have been achieved under atmospheric pressure conditions, they are significantly out of touch with the high-pressure conditions in engineering practice and cannot guide engineering design. For example, evaporators in fields such as food, chemical, chemical, papermaking, seawater desalination, environmental protection, waste heat utilization, and nuclear energy all operate under high-pressure conditions.

[0003] Pressure, as a key parameter, systematically alters the thermophysical properties of the working fluid, thus profoundly affecting the entire boiling heat transfer process. For example, under normal pressure, the boiling of water on a smooth metal surface has a distinct initial superheat threshold of approximately 4-5°C. Below this threshold, it is difficult to form stable vaporization nuclei, and boiling cannot be sustained. Theoretically, increased pressure leads to a decrease in surface tension, resulting in smaller and easier-to-generate bubbles. The latent heat of vaporization decreases, reducing the heat required to generate a unit mass of steam, meaning a greater steam production rate under the same heat flux, or the ability to initiate boiling at a smaller temperature difference. However, how the combined effects of these property changes specifically affect heat transfer characteristics currently lacks a clear mechanistic explanation and experimental verification, leading to significant uncertainties in existing models when predicting the performance of boiling under high pressure and small temperature differences.

[0004] Existing technologies lack experimental devices for testing the performance of high-temperature and high-pressure evaporators with double-sided phase change inside and outside the tubes. At the same time, there is a lack of testing and research on the heat transfer performance of double-phase change evaporators under high-temperature and high-pressure conditions. It is also impossible to measure the heat transfer of condensation inside the tubes and the amount of boiling evaporation outside the tubes due to the double-sided phase change condensation-boiling heat transfer. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a single-tube test device and method for performance testing of a condensing-boiling two-phase change evaporator, enabling the testing and research of the heat transfer performance of the two-phase change evaporator under high temperature and high pressure conditions, and obtaining the evaporation rate of the evaporator at different dryness fractions under different combinations of condensation pressure inside the tube and boiling pressure outside the tube; The solution adopted by this invention to solve the technical problem is: A single-tube test device for performance testing of a condensing-boiling two-phase change evaporator includes a test body, a measurement circuit connected to the test body, a condensation circuit connected to the test body, and a cooling circuit connected to the condensation circuit and the measurement circuit respectively. The test body includes a sleeve, a measuring tube and a condenser-evaporator tube disposed inside the sleeve and with their axes parallel to the sleeve, and a cap disposed at both ends of the sleeve and sealing the sleeve; the two ends of the measuring tube are connected to the measuring circuit; the two ends of the condenser-evaporator tube are connected to the condensation circuit.

[0006] In some possible implementations, the measurement circuit includes a constant flow pump, a water tank, and a heat exchanger connected in sequence; the heat exchanger is connected to the outlet of the measuring tube, and the constant flow pump is connected to the inlet of the measuring tube. The heat exchanger is connected to the cooling circuit.

[0007] In some possible implementations, the condensation circuit includes a heater, a plunger pump, a second water tank, and a second heat exchanger connected in sequence; the second heat exchanger is connected to the outlet of the condenser-evaporator tube, and the heater is connected to the inlet of the condenser-evaporator tube.

[0008] In some possible implementations, the cooling circuit includes a chiller connected to heat exchanger one and heat exchanger two, respectively.

[0009] In some possible implementations, the measurement circuit further includes a mass flow meter and a temperature sensor 1 disposed between the constant flow pump and the measuring tube, a temperature sensor 2 disposed between the outlet of the measuring tube and the heat exchanger 1, a pressure sensor 1 for testing the inlet and outlet pressure of the measuring tube, a back pressure valve 1 disposed between the heat exchanger 1 and the water tank 1, and a regulating valve 1 disposed between the constant flow pump and the water tank 1.

[0010] In some possible implementations, the condensation circuit further includes a pressure sensor 2 for testing the pressure at the inlet and outlet of the condenser evaporator tube, a regulating valve 2 and a mass flow meter 2 disposed between the heater and the plunger pump, a filter 1 disposed between the plunger pump and the water tank 2, a filter 2 and a back pressure valve 2 disposed between the water tank 2 and the heat exchanger 2, and a temperature sensor 3 disposed at the inlet and outlet of the condenser evaporator tube.

[0011] In some possible implementations, a temperature sensor four for measuring the temperature inside the sleeve and a pressure sensor three for measuring the pressure inside the sleeve are provided on the sleeve.

[0012] A single-tube test method for performance testing of a condensing-boiling two-phase change evaporator, based on the single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator described above; specifically: After adjusting the single-tube test apparatus to normal operation, the following steps were performed in sequence: calibrating the heat loss of the sleeve, adjusting and controlling the boiling pressure inside the sleeve, and measuring the evaporation rate of the condenser evaporator.

[0013] In some possible implementations, the calibration of the heat loss of the sleeve specifically refers to: the control measurement circuit is not connected to the measurement tube, steam is input into the condenser-evaporator tube, and the temperature of the liquid in the sleeve will rise along the water saturation curve until the temperature of the liquid is the same as the temperature of the steam in the condenser-evaporator tube; when the equilibrium is complete, the enthalpy difference between the inlet and outlet of the condenser-evaporator tube is the heat loss of the sleeve.

[0014] In some possible implementations, the adjustment and control of the boiling pressure inside the sleeve specifically refers to: By controlling the flow rate of room temperature water entering the measuring tube, the pressure inside the sleeve is controlled to reach the test conditions, thereby achieving the adjustment and control of the boiling pressure inside the sleeve.

[0015] In some possible implementations, the measurement of the evaporation rate of the condenser-evaporator tube specifically refers to the following: when the pressure inside the condenser-evaporator tube and the boiling pressure inside the sleeve both reach a stable state, the heat carried away by the measuring tube plus the heat dissipation loss of the sleeve equals the heat released by the condenser-evaporator tube. Based on the heat transfer and the temperature and pressure values ​​inside the sleeve, the mass flow rate of the evaporation outside the condenser-evaporator tube can be obtained.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention employs three independently operating circulation systems to complete heat exchange; the test body of the condensation-evaporation test device has a compact structure, with the measuring tube and the condensation-evaporation tube placed in the same circular sleeve; the measurement progress is high and the error is small, providing support for the study of the heat transfer performance of two-phase change evaporators under high temperature and high pressure conditions.

[0017] This invention can effectively solve the technical problem of testing the performance of two-phase change heat transfer under high temperature and high pressure boiling and condensation, shorten the product development cycle by more than 50%, reduce trial and error costs, and promote the progress of two-phase change heat transfer technology. The single-tube test apparatus in this invention is based on fundamental physical laws and is applicable not only to two-phase change evaporators but also to the performance studies of other heat exchangers, demonstrating good versatility. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the single-tube testing device in this invention; The components include: 1. Sleeve; 11. Temperature sensor four; 12. Pressure sensor three; 2. Measuring tube; 3. Condensation and evaporation tube; 4. Measurement circuit; 41. Constant flow pump; 42. Water tank 1; 43. Heat exchanger 1; 44. Mass flow meter 1; 45. Temperature sensor 1; 46. Temperature sensor 2; 47. Pressure sensor 1; 5. Condensation circuit; 51. Heater; 52. Plunger pump; 53. Water tank II; 54. Heat exchanger II; 55. Pressure sensor II; 56. Control valve II; 57. Mass flow meter II; 58. Back pressure valve II; 59. Temperature sensor III; 6. Cooling circuit. Detailed Implementation

[0019] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] The present invention will now be described in detail.

[0021] It should be noted that the condensation-boiling dual phase change specifically refers to the simultaneous occurrence of condensation inside the condensation-evaporation tube 3 and boiling outside the condensation-evaporation tube 3, that is, the phase change occurs simultaneously inside and outside the tube.

[0022] Example 1: like Figure 1 As shown, a single-tube test device for testing the performance of a condensing-boiling two-phase change evaporator includes a test body, a measurement circuit 4 connected to the test body, a condensation circuit 5 connected to the test body, and a cooling circuit 6 connected to the condensation circuit 5 and the measurement circuit 4 respectively. The test body includes a sleeve 1, a measuring tube 2 and a condenser-evaporator tube 3 disposed inside the sleeve 1 and with their axes parallel to the sleeve 1, and a cap disposed at both ends of the sleeve 1 and sealing the sleeve 1; the inlet of the measuring tube 2 is connected to the measuring circuit 4 to form a circuit; the inlet and outlet of the condenser-evaporator tube 3 are connected to the condensation circuit 5 to form a circuit. The inside of the sleeve 1 is sealed to form a natural circulation loop; that is, the condenser evaporator 3 and the measuring tube 2 are sealed and connected by the sleeve 1. After the steam is generated, it flows upward and condenses into liquid on the outside of the measuring tube 2 before flowing downward, forming a natural circulation loop inside the sleeve 1 to complete heat transfer and measurement. Furthermore, in the test body, the measuring tube 2 is a group and the condenser-evaporator tube 3 is a group; the sleeve 1, the condenser-evaporator tube 3, and the measuring tube 2 are all made of stainless steel, such as 304 stainless steel; the condenser-evaporator tube 3 is preferably a high-throughput tube.

[0023] The condensation circuit 5, the measuring circuit 4, and the natural circulation circuit formed in the sleeve 1 are all independently operating circulation circuits. The condensation circuit 5 and the measuring circuit 4 are open circuits, while the natural circulation circuit is a closed circuit. The working fluids of the three circuits (condensation circuit 5, measuring circuit 4, and natural circulation circuit) are independent of each other. There is only heat exchange and no mass exchange between the three circuits (condensation circuit 5, measuring circuit 4, and natural circulation circuit).

[0024] It should be noted that during the experiment, the measuring tube 2 will be positioned above the condenser-evaporator tube 3; the condensation circuit 5 completes the condensation process within the condenser-evaporator tube 3; it heats room temperature water to a given temperature, providing the condenser-evaporator tube 3 with saturated two-phase water vapor of the gas-liquid two-phase phase that meets the experimental requirements in terms of temperature, pressure, and dryness. The condenser-evaporator tube 3 releases heat, and the saturated two-phase water vapor flows along the condenser-evaporator tube 3, reducing the outlet dryness or turning into condensate. The high-temperature steam at the outlet of the condenser-evaporator tube 3 is cooled by the cooling circuit 6 and then flows back to its water tank; when the entire device is stable and the measuring circuit 4 is not working, the heat loss of the sleeve 1 can be calibrated; specifically, as the heat of the steam at the inlet of the condenser tube is continuously input, the temperature of the original liquid in the sleeve 1 will rise along the water saturation curve until it is almost the same as the temperature of the fluid in the condenser tube. When the temperature of the liquid in the sleeve 1 is completely balanced with that of the fluid in the condenser-evaporator tube 3, the enthalpy difference between the inlet and outlet of the condenser-evaporator tube 3 is the heat loss of the sleeve 1.

[0025] Specifically, the working fluid used in the test is deionized water. The condensation circuit 5 includes a heater 51, a plunger pump 52, a second water tank 53, and a second heat exchanger 54 connected in sequence. The plunger pump 52 is a high-pressure plunger pump. The second heat exchanger 54 is connected to the outlet of the condensation evaporation tube 3, and the heater 51 is connected to the inlet of the condensation evaporation tube 3, thereby forming a circulation circuit. The heater 51 is used to heat the room temperature water into saturated water vapor of the required gas-liquid two-phase phase, which is then transported into the condensation evaporation tube 3.

[0026] The measuring circuit 4 is mainly used for measuring the heat transfer of condensation and evaporation. After room temperature water enters the measuring tube 2, it flows along the axial direction of the measuring tube 2. After absorbing the heat in the sleeve 1, the temperature rises, but it still remains liquid. It flows out from the outlet of the measuring tube 2 and enters the cooling circuit 6. After being cooled, it flows back to its water tank (water tank 42) to obtain the temperature and pressure of the inlet and outlet of the measuring tube 2. Specifically, the measurement circuit 4 includes a constant flow pump 41, a water tank 42, and a heat exchanger 43 connected in sequence; the heat exchanger is connected to the outlet of the measurement tube 2, and the constant flow pump 41 is connected to the inlet of the measurement tube 2; the heat exchanger 43 is connected to the cooling circuit 6.

[0027] After the measurement circuit 4 is opened, room temperature water enters the measurement tube 2 and flows, carrying away the heat from the sleeve 1. When the heat carried away by the sleeve 1 is greater than the heat released by the condenser evaporator 3, the pressure and temperature inside the sleeve 1 gradually decrease; when the heat carried away by the sleeve 1 is less than the heat released by the condenser evaporator 3, the pressure and temperature inside the sleeve 1 gradually increase. By precisely controlling the inlet flow rate of the measurement tube 2 with an adjustment accuracy of 1 mL / min, the pressure inside the sleeve 1 can be precisely controlled to reach the test target.

[0028] In some possible implementations, the cooling circuit 6 is used to exchange heat with the working fluid in the measuring circuit 4 and the condensing circuit 5 respectively, so as to realize the recycling of the working fluid; the cooling circuit 6 includes a chiller connected to heat exchanger 43 and heat exchanger 54 respectively.

[0029] Specifically, heat exchanger 43 and heat exchanger 54 can be serpentine tube heat exchangers or plate heat exchangers; heat exchanger 43 is mainly used for heat exchange of the fluid in measuring tube 2; heat exchanger 54 is mainly used for heat exchange of the working fluid in condenser-evaporator tube 3; the chiller is used for heat exchange of heat exchanger 43 and heat exchanger 54, and it is connected in parallel with heat exchanger 43 and heat exchanger 54.

[0030] In some possible implementations, the measurement circuit 4 further includes a mass flow meter 44 and a temperature sensor 45 disposed between the constant flow pump 41 and the measuring tube 2, a second temperature sensor 46 disposed between the outlet of the measuring tube 2 and the heat exchanger 43, a pressure sensor 47 for testing the inlet and outlet pressure of the measuring tube 2, a back pressure valve 48 disposed between the heat exchanger 43 and the water tank 42, and a regulating valve 49 disposed between the constant flow pump 41 and the water tank 42.

[0031] Specifically, mass flow meter 44 is used to monitor the flow rate of the fluid entering the measurement circuit 4, temperature sensor 45 is used to monitor the temperature of the fluid entering the measurement tube 2, temperature sensor 46 is used to monitor the temperature of the fluid flowing out of the outlet of the measurement tube 2, back pressure valve 48 is used to regulate the pressure of the fluid returning to the water tank 42, and regulating valve 49 is used to regulate the flow rate of room temperature water entering the measurement tube 2.

[0032] In some possible implementations, the condensation circuit 5 further includes a pressure sensor 55 for testing the pressure at the inlet and outlet of the condenser evaporator 3, a regulating valve 56 and a mass flow meter 57 disposed between the heater 51 and the plunger pump 52, a filter 1 disposed between the plunger pump 52 and the water tank 53, a filter 2 and a back pressure valve 58 disposed between the water tank 53 and the heat exchanger 54, and a temperature sensor 59 disposed at the inlet and outlet of the condenser evaporator 3. Mass flow meter 57 is used to monitor the flow rate of the fluid delivered to heater 51 by plunger pump 52; regulating valve 56 is used to regulate the flow rate; back pressure valve 58 is used to regulate the pressure of the fluid returning to water tank 53; temperature sensor 59 is used to test the temperature at the inlet and outlet of condenser evaporator 3 respectively.

[0033] A temperature sensor 11 for measuring the temperature inside the sleeve 1 and a pressure sensor 12 for measuring the pressure inside the sleeve 1 are provided on the sleeve 1.

[0034] In this invention, a forced circulation system is formed by the condensation circuit 5 connected to the condenser evaporator 3 to complete the generation, condensation and cooling of steam; The present invention forms a forced circulation system by connecting the measuring tube 2 and the measuring circuit 4, thereby completing the heat absorption and cooling of the working fluid in the measuring tube 2; The present invention achieves both heat and mass transfer through the natural circulation system formed inside the sleeve 1. The liquid condensed outside the measuring tube 2 falls back into the saturated liquid by gravity, and the steam generated by the boiling of the saturated liquid rises to the top of the sleeve 1 by buoyancy and comes into contact with the outside of the measuring tube 2, thereby completing the cooling of the saturated steam and the boiling and evaporation of the saturated liquid.

[0035] This invention integrates the condenser-evaporator tube 3 and the measuring tube 2 into a single sleeve 1 and seals them together. The structure is compact and has low heat loss, thus enabling the measurement of small evaporation amounts under low dryness and low heat transfer temperature differences. It can also achieve evaporation amount measurement across the entire dryness range and provide support for the bubble point test measurement of boiling evaporation. The measuring tube 2 and the condenser-evaporator tube 3 are placed in the same circular sleeve 1, which greatly reduces heat loss and thus lowers the measurement limit for small evaporation amounts.

[0036] The single-tube test apparatus for the performance testing of the condensing boiling two-phase change evaporator described above was used for testing. Specifically, the test method involves, after adjusting the single-tube test apparatus to normal operation, sequentially calibrating the heat loss of sleeve 1, adjusting and controlling the boiling pressure inside sleeve 1, and measuring the evaporation rate of the condensing evaporator tube 3. The specific steps include: Step S1: Check the sealing and integrity of the test body; Step S2: Check whether the water levels in the condensation circuit 5, the measuring circuit 4, and the water chiller meet the test safety requirements; Step S3: Close the measurement circuit 4, start the water chiller, and open the condensation circuit 5. When the flow rate at the inlet of the condensation circuit 5 reaches the required flow rate for the test, adjust the back pressure valve 58 to reach the test pressure. Step S4: Check if the entire test system is working properly; after confirming that it is working properly, calibrate the heat loss of sleeve 1. Step S5: After the heat loss of sleeve 1 is calibrated, turn on heater 51 to gradually heat the deionized water entering the condenser evaporator 3 until the pressure and inlet dryness of the condenser evaporator 3 meet the test requirements. Step S6: Wait for the temperature and pressure inside the sleeve 1 to gradually increase. When it approaches the pressure value required by the test conditions, open the measurement circuit 4 and adjust the flow rate of room temperature water entering the measurement circuit 4 through the regulating valve 49 so that the pressure inside the sleeve 1 reaches the target value. Step S7: Adjust the pressure in the condensation circuit 5 by using back pressure valve 2 58 and adjust the flow rate of the working fluid in the measurement circuit 4 by using regulating valve 1 49 to stabilize it at the required pressure value under the test conditions. Step S8: Collect test data under stable operating conditions for 5 minutes, and calculate the evaporation rate of the condenser-evaporator tube 3 based on the test data; the test data includes the temperature and pressure inside the sleeve 1, the pressure and temperature at the inlet and outlet of the measuring tube 2, and the temperature and pressure at the inlet and outlet of the condenser-evaporator tube 3. Step S9: Adjust the pressure of condensing circuit 5 and the flow rate of measuring circuit 4, and repeat steps S7-S8 to complete the next test condition; Step S10: After completing the test, gradually reduce the heating power; Step S11: When the temperature inside the sleeve 1 is below 70°C, the pressure of the measuring circuit 4 and the condensation circuit 5 is reduced first through back pressure valve 48 and back pressure valve 58, and then the flow rate is gradually reduced until it is closed through regulating valve 49 and regulating valve 56. Step S12: Turn off the water chiller and check if the power supply to the remaining equipment is turned off; check if the main test unit is normal.

[0037] Specifically, the method for calibrating the heat loss of sleeve 1 refers to the following: the control measurement circuit 4 is not connected to the measurement tube 2, and saturated steam heated by heater 51 is input into the condenser evaporator tube 3. The liquid in sleeve 1 will increase in temperature along the saturation curve of water until the temperature of the liquid is almost the same as the temperature of the steam in the condenser evaporator tube 3. When the equilibrium is reached, the enthalpy difference between the inlet and outlet of the condenser evaporator tube 3 is the heat loss of sleeve 1.

[0038] Specifically, the method for adjusting and controlling the boiling pressure inside sleeve 1 refers to: Open the measurement circuit 4 and inject room temperature water into the measurement tube 2. The room temperature water in the measurement tube 2 will carry away the heat in the sleeve 1. When the heat carried away by the sleeve 1 is greater than the heat released by the condenser evaporator 3, the pressure and temperature in the sleeve 1 will gradually decrease. When the heat carried away by the sleeve 1 is less than the heat released by the condenser evaporator 3, the pressure and temperature in the sleeve 1 will gradually increase. Control the inlet flow rate of the measurement tube 2 by adjusting valve 49 to control the pressure in the sleeve 1 to meet the test conditions, thereby realizing the adjustment and control of the boiling pressure in the sleeve 1.

[0039] Specifically, the method for measuring the evaporation rate of the condenser-evaporator tube 3 refers to the following: when the pressure inside the condenser-evaporator tube 3 and the boiling pressure inside the sleeve 1 both reach a stable state, the heat carried away by the measuring tube 2 plus the heat dissipation loss of the sleeve 1 equals the heat released by the condenser-evaporator tube 3. Based on the heat transfer and the temperature and pressure values ​​inside the sleeve 1, the mass flow rate of the evaporation outside the condenser-evaporator tube 3 can be obtained.

[0040] Example 2: This embodiment is based on a single-tube test device for performance testing of a condensing-boiling two-phase change evaporator. Under the conditions that the condensing pressure inside the condensing-evaporating tube 3 is 6.0-6.4 MPa and the boiling pressure outside the condensing-evaporating tube 3 is 5.0-5.6 MPa, the evaporation capacity test in the single-tube two-sided phase change evaporator was carried out, and the evaporation capacity measurement results in the full dryness range were obtained. When calibrating the heat loss of sleeve 1, when the flow rate is not flowing through the measuring tube 2, as the heat of the steam at the inlet of the condenser-evaporator tube 3 is continuously input, the original liquid in sleeve 1 will increase in temperature along the water saturation curve until it is almost the same as the temperature of the fluid in the condenser-evaporator tube 3. When it is in complete equilibrium, the enthalpy difference between the inlet and outlet of the condenser-evaporator tube 3 is the heat loss of sleeve 1.

[0041] When precisely adjusting and controlling the boiling pressure inside sleeve 1, the flow rate of measuring tube 2 is turned on. The water inlet of measuring tube 2 is at room temperature, and measuring tube 2 carries away the heat inside sleeve 1. When the heat carried away by sleeve 1 is greater than the heat released by condenser evaporator 3, the pressure and temperature inside sleeve 1 gradually decrease. When the heat carried away by sleeve 1 is less than the heat released by condenser evaporator 3, the pressure and temperature inside sleeve 1 gradually increase. By precisely controlling the inlet flow rate of measuring tube 2 with an adjustment accuracy of 1 mL / min, the pressure inside sleeve 1 can be precisely controlled to reach the test target.

[0042] When measuring the evaporation rate of the condenser evaporator 3, in order to facilitate the measurement of the enthalpy change of the water in the measuring tube 2 after heat absorption, it is necessary to ensure that the liquid in the measuring tube 2 does not boil. Therefore, it is necessary to control the pressure of the measuring circuit 4 to be higher than 8.5 MPa, which is much higher than the corresponding saturation pressure at the test temperature. Specifically, the highest temperature and pressure in the sleeve 1 is 5.6 MPa, corresponding to a saturation temperature of 271.1℃. When the test system is stable, that is, when the pressure inside the condenser-evaporator tube 3 and the boiling pressure inside the sleeve 1 both reach a stable state, the heat carried away by the measuring tube 2 plus the heat loss of the sleeve 1 equals the heat released by the condenser-evaporator tube 3. Based on the heat transfer and the temperature and pressure values ​​inside the sleeve 1, the mass flow rate of the evaporation outside the tube can be obtained.

[0043] The results show that: (1) Under the measurement conditions, the evaporation rate of condensation evaporation ranges from 1.0 to 8.0 g / s; the evaporation rate is the mass flow rate. (2) As the dryness increases, the evaporation rate tends to increase gradually; (3) The greater the pressure difference between condensation in the condenser-evaporator tube 3 and boiling in the sleeve 1, that is, the greater the heat transfer temperature difference, the greater the evaporation rate.

[0044] Therefore, it can be seen that the present invention can realize the measurement of evaporation of a high-temperature and high-pressure condensation and evaporation double-sided phase change single tube evaporator across the entire dryness range.

[0045] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator, characterized in that, It includes a test body, a measurement circuit connected to the test body, a condensation circuit connected to the test body, and a cooling circuit connected to both the condensation circuit and the measurement circuit. The test body includes a sleeve, a measuring tube and a condenser-evaporator tube arranged inside the sleeve with their axes parallel to the sleeve, and caps arranged at both ends of the sleeve to seal the sleeve. The two ends of the measuring tube are connected to the measuring circuit; The two ends of the condenser-evaporator tube are connected to the condensation circuit.

2. The single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator according to claim 1, characterized in that, The measurement circuit includes a constant flow pump, a water tank, and a heat exchanger connected in sequence; the heat exchanger is connected to the outlet of the measuring tube, and the constant flow pump is connected to the inlet of the measuring tube. The heat exchanger is connected to the cooling circuit.

3. The single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator according to claim 2, characterized in that, The condensation circuit includes a heater, a plunger pump, a second water tank, and a second heat exchanger connected in sequence; the second heat exchanger is connected to the outlet of the condenser-evaporator tube, and the heater is connected to the inlet of the condenser-evaporator tube.

4. The single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator according to claim 3, characterized in that, The cooling circuit includes chillers connected to heat exchanger one and heat exchanger two, respectively.

5. The single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator according to claim 2, characterized in that, The measurement circuit also includes a mass flow meter and a temperature sensor 1 installed between the constant flow pump and the measuring tube, a temperature sensor 2 installed between the outlet of the measuring tube and the heat exchanger 1, a pressure sensor 1 used to test the pressure at the inlet and outlet of the measuring tube, and a back pressure valve 1 installed between the heat exchanger 1 and the water tank 1. The condensation circuit also includes a pressure sensor 2 for testing the pressure at the inlet and outlet of the condenser evaporator tube, a regulating valve 2 and a mass flow meter 2 located between the heater and the plunger pump, a filter 1 located between the plunger pump and the water tank 2, a filter 2 and a back pressure valve 2 located between the water tank 2 and the heat exchanger 2, and a temperature sensor 3 located at the inlet and outlet of the condenser evaporator tube.

6. The single-tube test apparatus for performance testing of a condensing-boiling two-phase change evaporator according to claim 1, characterized in that, A temperature sensor four for measuring the temperature inside the sleeve and a pressure sensor three for measuring the pressure inside the sleeve are provided on the sleeve.

7. A single-tube test method for performance testing of a condensing-boiling two-phase change evaporator, characterized in that, The single-tube test device for performance testing of a condensing-boiling two-phase change evaporator according to any one of claims 1-6; specifically, after adjusting the single-tube test device to normal operation, the following steps are performed in sequence: calibrating the heat loss of the sleeve, adjusting and controlling the boiling pressure inside the sleeve, and measuring the evaporation rate of the condensing-boiling tube.

8. The single-tube test method for performance testing of a condensing-boiling two-phase change evaporator according to claim 7, characterized in that, The aforementioned sleeve heat dissipation loss calibration specifically refers to: when the control measurement circuit is not connected to the measurement tube, steam is input into the condenser-evaporator tube, and the liquid in the sleeve will increase in temperature along the water saturation curve until the temperature of the liquid is the same as the temperature of the steam in the condenser-evaporator tube; when they are in perfect equilibrium, the enthalpy difference between the inlet and outlet of the condenser-evaporator tube is the heat dissipation loss of the sleeve.

9. A single-tube test method for performance testing of a condensing-boiling two-phase change evaporator according to claim 7, characterized in that, The adjustment and control of the boiling pressure inside the sleeve specifically refers to: By controlling the flow rate of room temperature water entering the measuring tube, the pressure inside the sleeve is controlled to meet the test conditions, thereby achieving the adjustment and control of the boiling pressure inside the sleeve.

10. A single-tube test method for performance testing of a condensing-boiling two-phase change evaporator according to claim 7, characterized in that, The measurement of the evaporation rate of the condenser-evaporator tube specifically refers to the following: when the pressure inside the condenser-evaporator tube and the boiling pressure inside the sleeve both reach a stable state, the heat carried away by the measuring tube plus the heat loss from the sleeve equals the heat released by the condenser-evaporator tube. Based on the heat transfer and the temperature and pressure values ​​inside the sleeve, the mass flow rate of the evaporation outside the condenser-evaporator tube can be obtained.

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