CN108151918B - A heat meter durability test device and its test method - Google Patents

Abstract

The invention provides a heat meter durability test device and a test method thereof. The heat meter durability test device includes a constant temperature hot water tank, a constant temperature cold water tank, a test pipeline and a flow rate composed of a flow control valve and an electromagnetic flowmeter in series Adjustment pipeline; wherein, the constant temperature hot water tank is connected to the inlet of the test pipeline through the first water outlet pipeline, and the first variable frequency water pump pumps hot water into the test pipeline; the outlet of the test pipeline passes through two paralleled The flow regulating pipelines are respectively connected with the constant temperature hot water tank to form a large circulation pipeline for the hot water test; a first thermometer and a first pressure transmitter are set at the entrance of the test pipeline, and set at the exit of the test pipeline Second thermometer, second pressure transmitter. The invention adopts independent high temperature water and low temperature water supply, and provides four circulation pipelines of large circulation and small circulation to meet the requirements of different durability tests, and the valve is automatically switched, which not only saves energy but also protects the detection instrument.

Description

A heat meter durability test device and its test method

technical field

The invention relates to a calorimeter verification device, in particular to a calorimeter durability test device and a test method thereof.

Background technique

The use of heat meters for heating household metering is an important part of heating reform. In my country, the actual use of heat meters for household metering has been in the pilot program for more than ten years, and the number of installed and used heat meters has been huge. Judging from the daily inspection statistics, the first inspection pass rate of the heat meter is relatively stable, but from the feedback information in use, the problems in the product quality of the heat meter are mainly reflected in the long-term reliability.

The durability of the heat meter directly affects the service life of the heat meter. Since there is no corresponding test standard in my country, most heat meter manufacturers mainly test the durability of the heat meter according to European standards. However, in the existing heat meter durability test device, when 4000 temperature cycle impact tests are performed, problems such as accuracy drop or even failure may occur, which affects the accuracy of the test structure.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a heat meter durability test device and a test method thereof, so as to overcome the defects of the prior art.

In order to achieve the above purpose, the present invention provides a heat meter durability test device, the heat meter durability test device includes a constant temperature hot water tank, a constant temperature cold water tank, a test pipeline, and is composed of a flow regulating valve and an electromagnetic flowmeter in series. The constant temperature hot water tank is connected to the inlet of the test pipeline through the first water outlet pipeline, and the first variable frequency water pump pumps hot water into the test pipeline; the constant temperature cold water tank passes through the second water outlet pipeline It is connected with the inlet of the test pipeline, and the second variable frequency water pump pumps cold water into the test pipeline; the outlet of the test pipeline is respectively connected with the constant temperature hot water tank and the constant temperature cold water tank through the two parallel flow regulating pipelines. To form a large circulation pipeline for hot water test and a large circulation pipeline for cold test; a first thermometer and a first pressure transmitter are set at the entrance of the test pipeline, and a second thermometer and a second thermometer are set at the outlet of the test pipeline. Pressure transmitter; the test pipe is composed of the A measured meter group and the B measured meter group connected in parallel. The constant temperature hot water tank is connected to the inlet of the A measured meter group through the third water outlet pipeline, and the third variable frequency water pump is connected. Pump hot water into the measured meter group A; the outlet of the A measured meter group is connected to the constant temperature hot water tank through a flow regulating pipeline to form a small circulation pipeline for the hot water test; the A measured meter group inlet The third thermometer and the third pressure transmitter are set at the place, and the fourth thermometer and the fourth pressure transmitter are set at the mouth of the measured meter group A; the constant temperature cold water tank is connected to the B measured meter group through the fourth outlet pipeline The inlet is connected, and the fourth variable frequency water pump pumps cold water to the B measured meter group; A fifth thermometer and a fifth pressure transmitter are arranged at the entrance of the measured meter group, and a sixth thermometer and a sixth pressure transmitter are arranged at the entrance of the B measured meter group.

As a further description of the heat meter durability test device of the present invention, preferably, the hot water branched from the first water outlet pipeline is connected to the constant temperature hot water tank from the circulation pipeline, and the constant temperature hot water tank is controlled by a flow control valve The circulating flow rate; the cold water branched from the second water outlet pipeline is connected to the constant temperature cold water tank from the circulating pipeline, and the self-circulating flow rate of the constant temperature cold water tank is controlled by the flow regulating valve.

As a further description of the heat meter durability test device of the present invention, preferably, the constant temperature hot water tank is provided with a hot water supply pipeline, a heater is arranged on the hot water supply pipeline, and the supplementary hot water is controlled by a second on-off valve; The constant temperature cold water tank is provided with a cold water supply pipeline, and the hot water supply pipeline is controlled by a second switch valve to supply cold water.

As a further description of the heat meter durability test device of the present invention, preferably, a seventh thermometer and a first liquid level gauge are arranged in the constant temperature hot water tank, and the seventh thermometer measures the temperature of the hot water in the constant temperature hot water tank, and the heating The device heats the supplemented hot water to the required temperature according to the temperature value of the seventh thermometer, the first liquid level meter measures the change of the hot water level in the constant temperature hot water tank, and the second switch valve is based on the hot water volume of the first liquid level meter. Supplement hot water; an eighth thermometer and a second liquid level gauge are set in the constant temperature cold water tank, the second liquid level gauge measures the change of the cold water level in the constant temperature hot water tank, and the second switch valve is based on the cold water volume of the second second liquid level gauge. Replenish cold water.

As a further description of the heat meter durability test device of the present invention, preferably, the length of the straight pipe section at the front end of each of the measured meters in the A measured meter group and the B measured meter group is 10 times the diameter of the measured meters , the length of the straight pipe section at the rear end is 5 times the diameter of the measured meter.

As a further description of the heat meter durability test device of the present invention, preferably, the constant temperature hot water tank adopts a sealed water tank, and the first water outlet pipeline, the third water outlet pipeline and the test pipeline are laid with thermal insulation layers to prevent heat transfer. Evaporation of the medium and loss of medium temperature.

The present invention also provides a test method utilizing the heat meter durability test device, the method comprising the following steps:

Step 1) 2400 hours durability test

Turn off the second variable frequency water pump, the third variable frequency water pump and the fourth variable frequency water pump, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines, start the first variable frequency water pump and heat the constant temperature hot water tank. The water is circulated and pumped into the test pipeline for a 2400-hour durability test, and the hot water temperature is 80-85°C; or

Step 2) 1000 hours additional durability test

Turn off the second variable frequency water pump, the third variable frequency water pump and the fourth variable frequency water pump, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines to the maximum flow _qs , start the first variable frequency water pump and heat the constant temperature The hot water in the water tank is circulated and pumped into the test pipeline, and the durability test is carried out at a hot water temperature of 80-85 °C for the first 500 hours; the durability test is carried out by adding 90-95 °C hot water to the constant temperature hot water tank for the next 500 hours. ;or

Step 3) 4000 times temperature cycle impact test

Turn off the third variable frequency water pump and the fourth variable frequency water pump, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines as the common flow q _p , and alternately start the first variable frequency water pump and the second variable frequency water pump to make The hot water pumping test pipeline in the constant temperature hot water tank and the cold water pumping test pipeline in the constant temperature cold water tank are alternately carried out, and during the circulation process of one water tank, the other water tank is self-circulating at the same flow rate, and the hot water temperature It is 80～85℃, and the cold water temperature is 15～20℃.

As a further description of the test method of the present invention, preferably, the flow regulating valves in the two parallel flow regulating pipelines are switched to avoid the flow shock caused by the valves being fully opened and fully closed.

As a further description of the test method of the present invention, preferably, in the 2400-hour durability test in step 1), the flow rate starts from 1.5 q _i , and the flow rate is evenly increased to q _p in 15 minutes, and after running for 8 hours at q _p , using 15min to increase the flow evenly to q _s , after running for 1h at q _s , reduce the flow to q _p evenly in 15min, after running 8h under q _p , use 15min to reduce the flow to 1.5qi evenly, at 1.5qi It runs for 6h and completes a cycle of 24h flow change.

The invention adopts separate high-temperature water and low-temperature water supply, and provides four circulation pipelines of large circulation and small circulation to meet the requirements of different durability tests, and can realize the basic durability test of 2400 hours and the additional 500 hours specified in European standards. Durability test, 4000 temperature cycle shock test and 4000 flow shock test.

Description of drawings

FIG. 1 is a schematic structural diagram of the heat meter durability test device of the present invention.

Detailed ways

In order to be able to further understand the structure, features and other purposes of the present invention, the following detailed description is now given in conjunction with the attached preferred embodiments and accompanying drawings. The embodiments described in the drawings are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. this invention.

As shown in FIG. 1, FIG. 1 is a schematic diagram of the structure of the heat meter durability test device of the present invention; the heat meter durability test device includes a constant temperature hot water tank 1, a constant temperature cold water tank 2, a test pipeline 3 and a flow regulating A flow regulation pipeline composed of a valve and an electromagnetic flowmeter in series; wherein, the constant temperature hot water tank 1 is connected to the inlet of the test pipeline 3 through the first water outlet pipeline 11, and is pumped into the test pipeline 3 by the first variable frequency water pump 13 Hot water; the constant temperature cold water tank 2 is connected to the inlet of the test pipeline 3 through the second water outlet pipeline 21, and the cold water is pumped into the test pipeline 3 by the second variable frequency water pump 23; the outlet of the test pipeline 3 is connected by two parallel The flow regulating pipeline is respectively connected with the constant temperature hot water tank 1 and the constant temperature cold water tank 2 to form a large circulation pipeline for hot water test and a large circulation pipeline for cold test; a first thermometer 31 is set at the entrance of the test pipeline 3 , a first pressure transmitter 32, a second thermometer 33 and a second pressure transmitter 34 are set at the outlet of the test pipeline 3.

The test pipeline 3 is composed of the A tested meter group 35 and the B tested meter group 36 connected in parallel. Preferably, the installation of the tested meter meets its requirements for the front and rear straight pipe sections and the direction of the pipeline, and the A tested meter group 35 The length of the straight pipe section at the front end of each meter under test in the group 36 of meters under test and B is 10 times the diameter of the meter under test, and the length of the straight pipe section at the rear end is 5 times the diameter of the meter under test.

The constant temperature hot water tank 1 is communicated with the inlet of the measured meter group A 35 through the third water outlet pipeline 12, and the third variable frequency water pump 14 pumps hot water to the A measured meter group 35; the outlet of the A measured meter group 35 Connected with the constant temperature hot water tank 1 through one of the flow regulation pipelines to form a small circulation pipeline for the hot water test; A third thermometer 351 and a third pressure transmitter 352 are arranged at the entrance of the measured meter group 35, A A fourth thermometer 353 and a fourth pressure transmitter 354 are arranged at the mouth of the measured meter group 35 .

The constant temperature cold water tank 2 is communicated with the inlet of the B measured meter group 36 through the fourth water outlet pipeline 22, and the fourth variable frequency water pump 24 pumps cold water to the B measured meter group 36; the outlet of the B measured meter group 36 passes through a The flow regulating pipeline is communicated with the constant temperature cold water tank 2 to form a small circulation pipeline for the cold water test; a fifth thermometer 361 and a fifth pressure transmitter 362 are provided at the entrance of the B measured meter group 36, and the B measured meter group A sixth thermometer 363 and a sixth pressure transmitter 364 are provided at the entrance of 36 .

The electromagnetic flowmeter used to measure the indication value of the instantaneous flow, its measurement range covers the nominal maximum flow to the minimum flow of the device, the accuracy level is not lower than 0.5, and the electromagnetic flowmeter and flow control valve are installed in the test pipeline The downstream of the test pipeline 3, that is, the outlet of the test pipeline 3 and the outlet of the A measured meter group 35 and the B measured meter group 36, are provided with flow regulating pipelines.

The thermometer used to measure the water temperature of the pipeline has a measurement range of (0~100) °C, an accuracy of 0.5 °C, and a display resolution of 0.1 °C. The temperature is set at the inlet and outlet of the test pipeline 3 and in the water tank The collection points, and the inlets and outlets of the branch test pipeline A to be measured meter group 35 and B to be measured meter group 36 are also set in the same way.

The pressure transmitter used to measure the pressure of the test pipeline has a measurement range of (0 to 1) MPa and an accuracy level of 0.5. Pressure collection points are set at the inlet and outlet of the test pipeline 3 respectively. The pressure measurement points are set at the front and back of the meter, the pressure can be adjusted and ensure that the pressure in front of and behind the meter under test is not more than 1.0MPa, not less than 0.1MPa, and the branch test pipeline A is measured in groups 35 and B. The inlet and outlet of the meter group 36 are also provided in the same manner.

Preferably, the hot water branched from the first water outlet pipeline 11 is connected to the thermostatic hot water tank 1 from the circulation pipeline 15, and the self-circulation flow rate of the thermostatic hot water tank 1 is controlled by a flow regulating valve; the second water outlet pipeline 21 is divided into The self-circulation pipeline 25 of the dissipated cold water is connected to the constant temperature cold water tank 2, and the self-circulation flow rate of the constant temperature cold water tank 2 is controlled by a flow regulating valve. For 4000 temperature shock tests, two sets of water pumps and water tank self-circulation pipelines are equipped. When one set of water pumps leads the water in the low temperature (or high temperature) water tank into the test pipeline, the other set of pumps makes the high temperature (or low temperature) water tank enter the test pipeline. The water is in a self-circulating state, the purpose is to avoid sudden changes in flow rate when the two stages are switched, so that the switching process is more stable and the stability of the equipment operation is enhanced. It ensures the stability of flow and pressure when switching between high and low temperature for 4000 times of temperature shock test. The invention adopts separate high-temperature water and low-temperature water supply, one water pump works (hot or cold water), and the other water pump runs on standby at the same flow rate through the bypass pipeline. Undisturbed switching of hot and cold water, with 2400 hours and 4000 temperature shock and flow shock tests in line with European standards.

The constant temperature hot water tank 1 is provided with a hot water supply pipeline 16, and a heater 17 is arranged on the hot water supply pipeline 16 to control the supply of hot water through a second on-off valve 18; the constant temperature cold water tank 2 is provided with a cold water supply pipeline 26, and the heat supply The water replenishment pipeline 26 controls the replenishment of cold water through the second switch valve 27 . A seventh thermometer 161 and a first liquid level gauge 162 are arranged in the constant temperature hot water tank 1 , the seventh thermometer 161 measures the temperature of the hot water in the constant temperature hot water tank 1 , and the heater 17 supplements the heat according to the temperature value of the seventh thermometer 161 . When the water is heated to the required temperature, the first liquid level gauge 162 measures the change of the hot water level in the constant temperature hot water tank 1, and the second switch valve 18 supplements the hot water according to the hot water amount of the first liquid level gauge 162; the constant temperature cold water tank 2 An eighth thermometer 261 and a second liquid level meter 262 are arranged inside, the second liquid level meter 262 measures the change of the cold water level in the constant temperature hot water tank 1, and the second on-off valve 27 is supplemented according to the amount of cold water of the second liquid level meter 262 cold water. Due to the long duration of a durability test, such as 100 days for a 2400-hour durability test, the evaporation of the liquid may occur during the operation of the system, resulting in the reduction of the liquid. In order to ensure the long-term operation of the system, the system is equipped with an automatic water replenishing device , The automatic water replenishment device uses external water source to replenish water. During the replenishment process, the system liquid temperature meets the requirements of (15 ~ 20) ℃, (80 ~ 85) ℃, (90 ~ 95) ℃. In addition, the constant temperature hot water tank 1 adopts a sealed water tank, and the first water outlet pipeline 11, the third water outlet pipeline 12 and the test pipeline 3 are laid with insulation layers to prevent the evaporation of the heat-carrying medium and the loss of the medium temperature.

The present invention also provides a test method utilizing the heat meter durability test device, the method comprising the following steps:

Step 1) 2400 hours durability test

Turn off the second variable frequency water pump 23, the third variable frequency water pump 14 and the fourth variable frequency water pump 24, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines, start the first variable frequency water pump 13 and heat the constant temperature hot water. The hot water in the box 1 is circulated and pumped into the test pipeline 3 for a 2400-hour durability test, and the hot water temperature is 80-85 °C;

The 2400-hour durability test starts from the flow rate of 1.5q _i , and increases the flow rate to q _p in 15 minutes. After 8 hours of operation at q _p , the flow rate is increased to q _s in 15 minutes. After 1 hour of operation under q _s , the The flow rate is evenly reduced to q _p in 15min. After running at q _p for 8h, the flow rate is reduced to 1.5qi in 15min. After running at 1.5qi for 6h, a cycle of 24h flow rate change is completed. When the device is at a stable flow point, the allowable deviation of the usual flow q _p and 1.5 times the minimum flow q _i is ±5%; the allowable deviation of the maximum flow q _s is -5%.

Step 2) 1000 hours additional durability test

Turn off the second variable frequency water pump 23, the third variable frequency water pump 14 and the fourth variable frequency water pump 24, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines to the maximum flow _qs , and start the first variable frequency water pump 13 The hot water in the constant temperature hot water tank 1 is circulated and pumped into the test pipeline 3, and the durability test is carried out at a hot water temperature of 80 to 85 °C for the first 500 hours; after 500 hours, 90 to 95 ℃ hot water for durability test.

Step 3) 4000 times temperature cycle impact test

Turn off the third variable frequency water pump 14 and the fourth variable frequency water pump 24, preset the opening of the flow regulating valve in the two parallel flow regulating pipelines to the usual flow _qp , and alternately start the first variable frequency water pump 13 and the second variable frequency water pump 23, so that the hot water in the constant temperature hot water tank 1 is pumped into the test pipeline 3 and the cold water pump in the constant temperature cold water tank 2 is injected into the test pipeline 3 alternately, and during the circulation process of one water tank, the other water tank is in the same way. The flow rate is self-circulating, the temperature of hot water is 80-85°C, and the temperature of cold water is 15-20°C. Each stage is 2.5 minutes and 5 minutes is 1 cycle.

In order to ensure that the difference between the actual flow value and the theoretical flow value during the 15-minute flow switching process is not greater than 10%, the electromagnetic flowmeter, flow regulating valve, and variable frequency pump form a complete closed-loop system, and cooperate with the system pressure control to ensure the smooth switching process. Due to the wide flow range, two electromagnetic flow control valves are selected in the design, that is, the flow control valves in the two parallel flow control pipelines are switched. The flow shock caused by the full opening and closing adopts the method of preset valve opening to realize the non-disturbance switching.

It should be stated that the above content of the invention and the specific embodiments are intended to prove the practical application of the technical solutions provided by the present invention, and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make various modifications, equivalent replacements or improvements within the spirit and principle of the present invention. The protection scope of the present invention is based on the appended claims.

Claims (8)

1. A heat meter durability test device, characterized in that the heat meter durability test device comprises a constant temperature hot water tank (1), a constant temperature cold water tank (2), a test pipeline (3) and a flow regulating valve. A flow regulating pipeline formed in series with an electromagnetic flowmeter; among them, The constant temperature hot water tank (1) is communicated with the inlet of the test pipeline (3) through the first water outlet pipeline (11), and the first variable frequency water pump (13) pumps hot water into the test pipeline (3); constant temperature cold water The box (2) is communicated with the inlet of the test pipe (3) through the second water outlet pipe (21), and the second variable frequency water pump (23) pumps cold water into the test pipe (3); the test pipe (3) The outlet of the water heater is respectively connected with the constant temperature hot water tank (1) and the constant temperature cold water tank (2) through the two parallel flow regulating pipelines, so as to form a large circulation pipeline for the hot water test and a large circulation pipeline for the cold water test; A first thermometer (31) and a first pressure transmitter (32) are arranged at the inlet of the pipeline (3), and a second thermometer (33) and a second pressure transmitter are arranged at the outlet of the test pipeline (3). (34); The test pipeline (3) is composed of the A measured meter group (35) and the B measured meter group (36) connected in parallel. The constant temperature hot water tank (1) is connected to the A measured meter through the third water outlet pipeline (12). The inlet of the group (35) is communicated, and the third variable frequency water pump (14) pumps hot water to the A measured meter group (35); the outlet of the A measured meter group (35) is connected to the flow regulating pipeline The constant temperature hot water tank (1) is connected to form a small circulation pipeline for the hot water test; a third thermometer (351) and a third pressure transmitter (352) are arranged at the entrance of the measured meter group (35) of A, and the A fourth thermometer (353) and a fourth pressure transmitter (354) are arranged at the outlet of the meter group (35); The constant temperature cold water tank (2) is communicated with the inlet of the B measured meter group (36) through the fourth water outlet pipeline (22), and the fourth variable frequency water pump (24) pumps cold water to the B measured meter group (36); The outlet of the B-measured meter group (36) is communicated with the constant temperature cold water tank (2) through a flow regulating pipeline to form a small circulation pipeline for the cold water test; the inlet of the B-measured meter group (36) is provided with a fifth A thermometer (361), a fifth pressure transmitter (362), a sixth thermometer (363) and a sixth pressure transmitter (364) are arranged at the outlet of the B measured meter group (36); The first water outlet pipeline (11) branches out from the hot water self-circulation pipeline (15) and is connected to the constant temperature hot water tank (1), and the self-circulation flow rate of the constant temperature hot water tank (1) is controlled by a flow regulating valve; The cold water self-circulation pipeline (25) branches from the water pipeline (21) and is connected to the constant temperature cold water tank (2), and the self-circulation flow rate of the constant temperature cold water tank (2) is controlled by a flow regulating valve. 2. The heat meter durability test device according to claim 1, wherein the constant temperature hot water tank (1) is provided with a hot water supply pipeline (16), and a heater is provided on the hot water supply pipeline (16). (17) and control the supplementary hot water through the second switch valve (18); the constant temperature cold water tank (2) is provided with a cold water supply pipeline (26), and the hot water supply pipeline (26) is controlled by the second switch valve (27) Replenish cold water. 3. The heat meter durability test device according to claim 2, characterized in that, a seventh thermometer (161) and a first liquid level meter (162) are arranged in the constant temperature hot water tank (1), and the seventh thermometer (161) ) measure the temperature of the hot water in the constant temperature hot water tank (1), the heater (17) heats the supplemented hot water to the required temperature according to the temperature value of the seventh thermometer (161), and the first liquid level gauge (162) measures the constant temperature The liquid level of the hot water in the hot water tank (1) changes, and the second on-off valve (18) supplements the hot water according to the amount of hot water from the first liquid level gauge (162); the constant temperature cold water tank (2) is provided with an eighth thermometer ( 261) and the second liquid level gauge (262), the second liquid level gauge (262) measures the change of the cold water level in the constant temperature hot water tank (1), and the second on-off valve (27) according to the second liquid level gauge ( 262) to supplement the cold water. 4. The heat meter durability test device according to claim 1, characterized in that, the length of the straight pipe section at the front end of each measured meter in the A measured meter group (35) and the B measured meter group (36) is 10 times the diameter of the gauge to be tested, and the length of the straight pipe section at the rear end is 5 times the diameter of the gauge to be tested. 5. The heat meter durability test device according to claim 1, characterized in that the constant temperature hot water tank (1) adopts a sealed water tank, the first water outlet pipeline (11), the third water outlet pipeline (12) and the test The pipeline (3) is laid with an insulating layer to prevent the heat-carrying medium from evaporating and the temperature of the medium from being lost. 6. A test method utilizing the heat meter durability test device as described in any one of claims 1-5, wherein the method comprises the steps: Step 1) 2400 hours durability test Turn off the second variable frequency water pump (23), the third variable frequency water pump (14) and the fourth variable frequency water pump (24), preset the opening of the flow regulating valve in the two parallel flow regulating pipelines, and start the first variable frequency water pump (13) The hot water in the constant temperature hot water tank (1) is circulated and pumped into the test pipeline (3) for a 2400-hour durability test, and the hot water temperature is 80-85°C; or Step 2) 1000 hours additional durability test Turn off the second variable frequency water pump (23), the third variable frequency water pump (14) and the fourth variable frequency water pump (24), and preset the opening degree of the flow regulating valve in the two parallel flow regulating pipelines to be the maximum flow _qs , Start the first variable frequency water pump (13) and circulate the hot water in the constant temperature hot water tank (1) into the test pipeline (3), and conduct a durability test at a hot water temperature of 80-85°C for the first 500 hours; Supplement 90-95°C hot water to the constant temperature hot water tank (1) every hour for durability test; or Step 3) 4000 times temperature cycle impact test Turn off the third variable frequency water pump (14) and the fourth variable frequency water pump (24), preset the opening degree of the flow regulating valve in the two parallel flow regulating pipelines to the usual flow _qp , and alternately start the first variable frequency water pump (13) ), the second variable frequency water pump (23), so that the hot water in the constant temperature hot water tank (1) is fed into the test pipeline (3) alternately with the cold water pump in the constant temperature cold water tank (2) into the test pipeline (3). , and during the circulation process of one water tank, the other water tank performs self-circulation at the same flow rate, the temperature of hot water is 80-85 ℃, and the temperature of cold water is 15-20 ℃. 7 . The test method according to claim 6 , wherein the flow regulating valves in the two parallel flow regulating pipelines are switched to avoid the flow shock caused by the valves being fully opened and fully closed. 8 . 8. test method as claimed in claim 6, it is characterised in that the 2400 hour durability test in step 1) is that the flow starts from 1.5q _i , and the flow is evenly increased to q _p with 15min, and runs 8h under q _p After running at _{q s} for 1 hour, the flow rate was evenly increased to q _s in 15 minutes, and the flow rate was reduced to q _p in 15 minutes. Run under qi for 6h, and complete a cycle of 24h flow changes.

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