Water heater with shell-and-tube structure and control method thereof

Abstract

The invention provides a water heater with a shell-and-tube structure and a control method thereof, a first end and a second end of a heat exchange tube are fixedly connected with an inlet tube plate and an outlet tube plate respectively, the first end is communicated with an inlet seal head, and the second end is not communicated with an outlet seal head; the outlet tube plate is provided with a through hole communicated with the tube shell and the outlet seal head; the steam inlet connecting pipe is arranged on one side close to the inlet sealing head; jet holes are formed in the heat exchange tubes; the steam inlet connecting pipe is provided with a steam pump, the cold water inlet pipe is provided with a cold water pump, the hot water outlet pipe is provided with a temperature sensor and a flowmeter, and the control system is in data connection with the steam pump and the cold water pump and used for controlling the frequency of the pumps according to data collected by the temperature sensor and / or data collected by the flowmeter. The novel structure and layout mode of the water heater are adopted, the water heater is of a shell-and-tube heat exchanger structure, the heat exchange area is enlarged, the mixing area is increased, and the temperature of output hot water is more uniform.

Description

Technical Field

[0001] This invention relates to a heat exchanger for direct mixing of two fluids, and more particularly to a shell-and-tube water heater for vapor-liquid mixing heat exchange. Background Technology

[0002] A water heater is a device that uses various physical principles to raise the temperature of cold water to produce hot water within a certain time. Based on different principles, they can be divided into electric water heaters, gas water heaters, solar water heaters, magnetic water heaters, air source water heaters, and central heating water heaters, etc.

[0003] In the prior art, CN106152480A discloses a gas water heater, comprising: a shell, with a cavity defined within the shell, and an inlet and an outlet; a catalytic burner, disposed within the cavity, with a premixing chamber defined within the catalytic burner, the catalytic burner having a fan interface and a gas interface communicating with the premixing chamber, a catalytic converter disposed within the catalytic burner, and a preheating section integrated on the catalytic converter; a fan, communicating with the fan interface to supply air to the premixing chamber; a gas proportional valve, the outlet of the gas proportional valve communicating with the gas interface to supply gas to the premixing chamber; and a heat exchanger, disposed within the shell and connected to the burner to absorb heat generated by the burner combustion, the heat exchanger having an inlet and an outlet, the inlet communicating with the inlet interface, and the outlet communicating with the outlet interface. The gas water heater according to embodiments of the present invention has a simple structure, reliable connections between components, safe operation, energy saving and environmental protection, and a good user experience.

[0004] CN106152539A discloses a constant temperature electric water heater, which includes an outer shell and an inner tank disposed therein. The outer shell is provided with a water inlet and a water outlet. A constant temperature device is connected to the water inlet at one end and to the water outlet at the other end. The constant temperature device has a first insulating tube, a second insulating tube, and a connecting tube and a hot water tee and a cold water tee that cooperate with each other. The constant temperature device has a constant temperature valve, which has a hot water inlet, a cold water inlet, and a drain outlet. The hot water inlet of the constant temperature valve is connected to the hot water tee, the cold water inlet of the constant temperature valve is connected to the cold water tee, and the drain outlet of the constant temperature valve is connected to the constant temperature water outlet. The cold water pipe in the first insulating tube is connected to the cold water tee through the connecting tube. A temperature regulator is provided at one end of the constant temperature valve. A sensing device and an automatic compensation device are provided between the water outlet of the outer shell and the constant temperature water outlet. The sensing device sends a signal to prompt the automatic compensation device to perform temperature compensation.

[0005] Shell-and-tube heat exchangers are widely used in industries such as chemical, petroleum, refrigeration, nuclear power, and energy. Due to the global energy crisis, the demand for heat exchangers in industrial production is increasing, and the quality requirements for heat exchangers are also becoming more stringent. In recent decades, although compact heat exchangers (plate, plate-fin, and welded plate heat exchangers, etc.), heat pipe heat exchangers, and direct contact heat exchangers have developed rapidly, shell-and-tube heat exchangers still dominate in terms of production and usage due to their high reliability and wide adaptability. According to relevant statistics, shell-and-tube heat exchangers still account for about 70% of all heat exchangers used in industrial plants.

[0006] In existing technologies, current water heaters, such as electric and gas water heaters, heat the water directly by immersing the heat source in cold water. This results in a small heating area, limited coverage, and uneven heating. Shell-and-tube heat exchangers, on the other hand, have a long heat exchange time and a large heat exchange area. This application adopts a novel water heater structure and layout, using a shell-and-tube heat exchanger to expand the heat exchange area, increase the mixing zone, and make the output hot water temperature more uniform. Summary of the Invention

[0007] In order to overcome the defects and deficiencies in the existing technology, the present invention provides a shell-and-tube water heater with vapor-liquid mixing, which can increase the heat exchange area, increase the mixing zone, and make the two fluids mix more evenly, resulting in a more uniform output hot water temperature.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A shell-and-tube water heater includes a heat exchanger comprising a shell, heat exchange tubes, a steam inlet pipe, an inlet end cap, and an outlet end cap. The steam inlet pipe is disposed on the shell, and a cold water inlet pipe and a hot water outlet pipe are respectively disposed on the inlet end cap and the outlet end cap. An inlet tube sheet is disposed between the inlet end cap and the shell, and an outlet tube sheet is disposed between the outlet end cap and the shell. The heat exchange tubes are disposed within the shell, and a first end and a second end of the heat exchange tubes are respectively fixedly connected to the inlet tube sheet and the outlet tube sheet, wherein the first end is connected to the inlet end cap, and the second end is not connected to the outlet end cap. The outlet tube sheet has a through hole connecting the shell and the outlet end cap. The steam inlet pipe is disposed on the side near the inlet end cap. Injection holes are provided on the heat exchange tubes. A steam pump is installed on the steam inlet pipe, a cold water pump is installed on the cold water inlet pipe, and a temperature sensor and flow meter are installed on the hot water outlet pipe. The control system is connected to the steam pump and the cold water pump for controlling the pump frequency based on the data collected by the temperature sensor and / or the data collected by the flow meter.

[0009] As an improvement, if the temperature sensor readings from the control system is lower than the preset temperature, the control system will increase the frequency of the steam pump and decrease the frequency of the cold water pump, thereby enabling the output temperature to quickly reach the preset temperature.

[0010] As an improvement, if the temperature sensor readings from the control system is higher than the preset temperature, the control system will reduce the frequency of the steam pump and increase the frequency of the cold water pump, thereby enabling the output temperature to quickly reach the preset temperature.

[0011] As an improvement, when the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously.

[0012] As an improvement, when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously.

[0013] As an improvement, the heat exchange tube has a triangular cross-section, and the lines connecting adjacent vertices of the triangle form an equilateral triangle. A tube wall is formed between adjacent vertices, and the tube wall is arc-shaped, with the curvature of the arc pointing towards the inner center of the equilateral triangle. Injection holes are formed on the tube wall to spray from the inside of the heat exchange tube to the outside.

[0014] A method for controlling the constant temperature and constant flow of a water heater, characterized in that the controller controls the frequency of the steam pump and the frequency of the cold water pump based on the detected flow rate to achieve a constant flow rate, including the following steps: 1) Achieving constant flow rate: When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously. 2) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature.

[0015] As an improvement, in step 2), a coarse adjustment is first performed to adjust the temperature within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump to keep the flow rate constant and achieve the predetermined temperature.

[0016] As an improvement, the controller adjusts the frequency of the steam pump and the cold water pump based on the detected flow rate to achieve a constant flow rate, including the following steps: 1) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature. 2) Achieving constant flow rate: When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously.

[0017] As an improvement, in step 2), a coarse adjustment is first performed to adjust the flow rate within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump, so as to achieve a constant flow rate while keeping the temperature constant.

[0018] Compared with the prior art, the present invention has the following advantages: 1. This application adopts a new structure and layout for water heaters, using a shell-and-tube heat exchanger structure to expand the heat exchange area, increase the mixing zone, and make the output hot water temperature more uniform.

[0019] 2. This application adopts a method of simultaneously controlling the evaporator pump and the chilled water pump, which can quickly achieve temperature and flow control, thus realizing dual control of temperature and flow.

[0020] 3. This invention increases the heat exchange area by modifying the triangular tube into an inwardly curved arc shape. Furthermore, the inward curve allows the fluid inside the tube to flow more from the center to the apex, increasing the pressure at the corners. Compared to other shapes, this reduces dead zones and avoids uneven spraying caused by uneven fluid distribution at different locations, resulting in a more uniform overall fluid spray. This application utilizes a triangular distribution of heat exchange tubes within the water heater, combined with the corresponding triangular shape of the heat exchange tubes, ensuring that the centers of the arcs between three adjacent heat exchange tubes converge at a single point, thus improving mixing and enhancing heat exchange efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the water heater structure of the present invention; Figure 2 This is a simplified schematic diagram of the control system of the present invention; Figure 3 This is a three-dimensional schematic diagram of the triangular jet heat exchanger tube of the present invention; Figure 4 This is a schematic diagram of the heat exchange tube arrangement of the water heater of the present invention. Detailed Implementation

[0022] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0023] Unless otherwise specified, in this article, " / " represents division, and "×" and "*" represent multiplication when formulas are involved.

[0024] This invention discloses a shell-and-tube type water heater. For example... Figure 1 As shown, the water heater includes a shell 2, a heat exchange tube 1, a steam inlet pipe 3, an inlet end cap 4, and an outlet end cap 5. The steam inlet pipe 3 is installed on the shell 2. A water inlet pipe 6 and a hot water outlet pipe 7 are respectively installed on the inlet end cap 4 and the outlet end cap 5. An inlet tube plate 8 is installed between the inlet end cap 4 and the shell 2, and an outlet tube plate 9 is installed between the outlet end cap 5 and the shell 2. The heat exchange tube 1 is installed in the shell 2. The first end 14 and the second end 15 of the heat exchange tube are fixedly connected to the inlet tube plate 8 and the outlet tube plate 9, respectively. The first end is connected to the inlet end cap 4, and the second end is not connected to the outlet end cap 5. The outlet tube plate is provided with a through hole 10 connecting the shell and the outlet end cap, and a jet hole 13 is provided on the heat exchange tube.

[0025] The cold water enters the heat exchange tube 1 through the cold water inlet pipe 6 and the end cap 4, and then exits through the jet hole 13 of the heat exchange tube 1. Because the second end of the heat exchange tube 1 is a closed structure, the cold water cannot directly enter the outlet end cap 5 through the second end, and therefore must flow out through the jet hole 13. Steam flows in through the steam inlet pipe 3, and then mixes and exchanges heat directly with the cold water flowing out through the jet hole 13 inside the tube shell 2. The hot water after heat exchange enters the outlet end cap through the through hole of the outlet tube plate, and then flows out from the hot water outlet pipe.

[0026] This application adopts a novel structure and layout for water heaters, using a shell-and-tube heat exchanger to expand the heat exchange area, increase the mixing zone, and make the output hot water temperature more uniform.

[0027] like Figure 1 As shown, a steam pump 22 is installed on the steam inlet pipe, a cold water pump 21 is installed on the cold water inlet pipe, and a temperature sensor and / or flow meter 23 is installed on the hot water outlet pipe. The control system 24 is connected to the steam pump, cold water pump, temperature sensor, and flow meter for data transmission, and is used to control the pump frequency based on the data collected by the temperature sensor and / or the data collected by the flow meter. This application adopts a method of simultaneously controlling the evaporation pump and the cold water pump, which can quickly achieve temperature and flow control, realizing dual control of temperature and flow.

[0028] As an improvement, if the temperature sensor reading is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the chilled water pump, thus quickly bringing the output temperature to the preset temperature. Conversely, if the temperature sensor reading is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the chilled water pump, again quickly bringing the output temperature to the preset temperature. Through the dual control of the chilled water pump and the steam pump, with one frequency increasing and the other decreasing, a constant temperature can be quickly achieved.

[0029] As an improvement, when the controller detects that the flow rate from the flow meter is lower than the preset flow rate, the controller simultaneously increases the frequency of both the steam pump and the chilled water pump. Conversely, when the controller detects that the flow rate from the flow meter is higher than the preset flow rate, the control system simultaneously decreases the frequency of both the steam pump and the chilled water pump. Through the dual control of the chilled water pump and the steam pump, with one frequency increasing and the other decreasing, a constant flow rate can be quickly achieved.

[0030] The above-described method for controlling the constant temperature and flow of a water heater is characterized in that the controller controls the frequency of the steam pump and the frequency of the cold water pump based on the detected flow rate to achieve a constant flow rate, comprising the following steps: 1) Achieving constant flow rate: When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously. 2) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature.

[0031] In the above setup, by simultaneously controlling the frequency changes of the two pumps, a constant flow rate is achieved first, followed by a constant temperature, thus achieving a dual stability of both flow rate and temperature.

[0032] As an improvement, in step 2), a coarse adjustment is first performed to adjust the temperature within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump to keep the flow rate constant and achieve the predetermined temperature.

[0033] In the above settings, the effect of stabilizing both flow rate and temperature can be quickly achieved by adjusting the line coarsely and then finely.

[0034] As an improvement, the controller adjusts the frequency of the steam pump and the cold water pump based on the detected flow rate to achieve a constant flow rate, including the following steps: 1) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature. 2) Achieving constant flow rate: When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously.

[0035] In the above setup, by simultaneously controlling the frequency changes of the two pumps, a constant temperature is achieved first, followed by a constant flow rate, thus achieving a dual stability of both flow rate and temperature.

[0036] As an improvement, in step 2), a coarse adjustment is first performed to adjust the flow rate within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump, so as to achieve a constant flow rate while keeping the temperature constant.

[0037] In the above settings, the effect of stabilizing both flow rate and temperature can be quickly achieved by coarse adjustment followed by fine adjustment.

[0038] like Figure 3 As shown, the heat exchange tube has a triangular cross-section, and the lines connecting adjacent vertices 11 form an equilateral triangle, with the tube wall 12 formed between adjacent vertices. Figure 1 As shown, the tube wall 12 is arc-shaped, with the curvature of the arc pointing inwards towards the inside of the equilateral triangle. Injection holes 13 are formed on the tube wall 12 to spray from the inside of the heat exchange tube outwards. As an improvement, the three arcs of the heat exchange tube have the same diameter and the same curvature. This arrangement ensures uniform circumferential spray volume.

[0039] This invention increases the heat exchange area by modifying the triangular tube into an inwardly curved arc shape. Moreover, because of the inwardly curved arc, the fluid inside the tube flows more from the center to the apex of the tube, thereby increasing the pressure at the corner. Compared with other shapes, this reduces the flow dead zone and avoids uneven spraying caused by uneven fluid distribution at different locations, thus making the overall sprayed fluid uniform.

[0040] As an improvement, the extension line of the spray direction of the spray orifice is oriented towards the center of the equilateral triangle. This arrangement ensures more uniform spraying from the center of the spray tube outwards, including better heat exchange with the fluid outside the tube.

[0041] As an improvement, the heat exchange tubes 1 are arranged in a triangular pattern, with the centers of the arcs between three adjacent heat exchange tubes converging at a single point. This application, through the triangular distribution of the heat exchange tubes within the water heater, combined with the corresponding triangular shape of the heat exchange tubes and the convergence of the centers of the arcs between three adjacent heat exchange tubes, achieves better mixing and improves heat exchange efficiency. The triangular tubes and triangular arrangement of this invention are mutually complementary and inseparable; their combined effect optimizes the mixing and heat exchange performance.

[0042] As an improvement, shell-and-tube water heaters are horizontally arranged, with varying nozzle densities on different heat exchange tubes. The nozzle density increases from bottom to top. Because steam has a low density, it tends to accumulate at the top as it flows. Therefore, increasing the nozzle density on the upper heat exchange tubes increases the amount of steam injected into the upper part of the water, allowing more fluid to mix and exchange heat with the upper steam. This optimizes the overall heat exchange effect and improves mixing heat exchange efficiency.

[0043] As an improvement, the distribution density of the injection holes in different heat exchange tubes increases progressively from bottom to top. This arrangement further optimizes the overall heat exchange effect and improves the efficiency of mixed heat exchange.

[0044] As an improvement, multiple baffles are installed inside the shell, including a lower baffle located at the bottom of the shell and an upper baffle located at the top of the shell, with the lower and upper baffles spaced apart. By installing baffles, the liquid flows in a tortuous manner, improving the heat exchange effect.

[0045] As an improvement, the spacing between adjacent baffles gradually increases from the shell-side inlet to the outlet. This is because the flow rate of the fluid in the shell-side continuously increases from the inlet to the outlet as mixing and heat transfer proceed. If the spacing remains constant, the flow velocity would increase, causing scouring of the shell-side outlet and increasing flow resistance. By increasing the spacing, the flow velocity remains relatively stable, thus ensuring a relatively balanced resistance throughout the flow process and preventing a decline in heat transfer efficiency due to increased downstream resistance.

[0046] As an improvement, the spacing between adjacent baffles gradually increases from the shell-side inlet to the outlet. This increasing spacing further balances the resistance throughout the flow process.

[0047] As an improvement, the heat exchange tubes are configured in multiple segments along the direction from the shell-side inlet to the outlet, with each segment having a different arc radius.

[0048] As an improvement, the curvature of the arc gradually decreases along the direction from the shell-side inlet to the outlet. By reducing the curvature, the flow area inside the heat exchange tube becomes larger, thereby gradually reducing the flow resistance towards the outlet. This results in more fluid flowing towards the outlet from inside the tube, leading to a more balanced amount of fluid ejected along the entire heat exchange tube direction, thus promoting heat transfer.

[0049] As an improvement, the rate of decrease in the curvature of the arc in different sections gradually increases along the direction from the shell-side inlet to the outlet. By varying the rate of decrease in the curvature, the amount of fluid injected along the entire heat exchange tube direction is further made relatively uniform, thereby further promoting heat transfer.

[0050] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A shell-and-tube water heater, wherein the heat exchanger includes a shell, heat exchange tubes, a steam inlet pipe, an inlet end cap, and an outlet end cap. The steam inlet pipe is disposed on the shell, and a cold water inlet pipe and a hot water outlet pipe are respectively disposed on the inlet end cap and the outlet end cap. An inlet tube sheet is disposed between the inlet end cap and the shell, and an outlet tube sheet is disposed between the outlet end cap and the shell. The heat exchange tubes are disposed in the shell, and a first end and a second end of the heat exchange tubes are respectively fixedly connected to the inlet tube sheet and the outlet tube sheet, wherein the first end is connected to the inlet end cap, and the second end is not connected to the outlet end cap. The outlet tube sheet has a through hole connecting the shell and the outlet end cap. The steam inlet pipe is disposed on the side near the inlet end cap. The heat exchange tubes have injection holes. A steam pump is installed on the steam inlet pipe, a cold water pump is installed on the cold water inlet pipe, and a temperature sensor and flow meter are installed on the hot water outlet pipe. The control system is connected to the steam pump and the cold water pump for controlling the pump frequency based on the data collected by the temperature sensor and / or the data collected by the flow meter.

2. The water heater as described in claim 1, characterized in that, If the temperature sensor readings collected by the control system is lower than the preset temperature, the control system will increase the frequency of the steam pump and decrease the frequency of the cold water pump, thereby enabling the output temperature to quickly reach the preset temperature.

3. The water heater as described in claim 1, characterized in that, If the temperature sensor readings from the control system is higher than the preset temperature, the control system will reduce the frequency of the steam pump and increase the frequency of the cold water pump, thereby enabling the output temperature to quickly reach the preset temperature.

4. The water heater as described in claim 1, characterized in that, When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller simultaneously increases the frequency of the steam pump and the frequency of the cold water pump.

5. The water heater as described in claim 1, characterized in that, When the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously.

6. The water heater as described in claim 1, characterized in that, The heat exchange tube has a triangular cross-section. The lines connecting adjacent vertices of the triangle form an equilateral triangle, and the tube wall is formed between adjacent vertices. The tube wall is arc-shaped, and the curvature of the arc is towards the inner center of the equilateral triangle. The tube wall has injection holes that spray from the inside of the heat exchange tube to the outside.

7. The constant temperature and constant current control method for a water heater as described in claim 1, characterized in that, The controller adjusts the frequency of the steam pump and the chilled water pump based on the detected flow rate to achieve a constant flow rate, including the following steps: 1) Achieving constant flow rate: When the controller detects that the flow rate of the flow meter is lower than the preset flow rate, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow rate of the flow meter is higher than the preset flow rate, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously. 2) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature.

8. The constant temperature and constant current control method for a water heater as described in claim 7, characterized in that, In step 2), a coarse adjustment is first performed to bring the temperature within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump while keeping the flow rate constant to achieve the predetermined temperature.

9. The constant temperature and constant current control method for a water heater as described in claim 1, characterized in that, The controller adjusts the frequency of the steam pump and the chilled water pump based on the detected flow rate to achieve a constant flow rate, including the following steps: 1) Achieving constant temperature: After the flow rate is constant, the controller adjusts the temperature to be constant. If the temperature sensor collected by the control system is lower than the preset temperature, the control system increases the frequency of the steam pump and decreases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature; if the temperature sensor collected by the control system is higher than the preset temperature, the control system decreases the frequency of the steam pump and increases the frequency of the cold water pump, so that the output temperature quickly reaches the preset temperature. 2) Achieving constant flow: When the controller detects that the flow meter flow is lower than the preset flow, the controller controls the frequency of the steam pump and the frequency of the cold water pump to increase simultaneously; when the controller detects that the flow meter flow is higher than the preset flow, the control system controls the frequency of the steam pump and the frequency of the cold water pump to decrease simultaneously.

10. The constant temperature and constant current control method for a water heater as described in claim 9, characterized in that, In step 2), a coarse adjustment is first performed to adjust the flow rate within the range, and then a fine adjustment is performed by increasing the frequency of the steam pump and decreasing the frequency of the cold water pump, so as to achieve a constant flow rate while keeping the temperature constant.

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