Fluid heater and domestic surface cleaning apparatus

Abstract

A fluid heater includes a heater body for heating an internal fluid, the heater body including a fluid inlet and a fluid outlet, and a flow path extending along an interior of the heater body between the fluid inlet and the fluid outlet; a pumping component for causing the internal fluid to flow substantially from the fluid inlet to the fluid outlet; an anisotropic valve in fluid communication with the flow path for causing the internal fluid within the heater body to exit the heater body; the anisotropic valve oriented in a direction generally along the flow path and splitting the internal fluid into a first fluid and a second fluid such that the first fluid and the second fluid have different flow rates. A household surface cleaning apparatus is also provided.

Description

Technical Field

[0001] This disclosure relates to a fluid heater and a household surface cleaning device. Background Technology

[0002] This disclosure relates to the field of household surface cleaning equipment, and particularly to fluid heating technology in devices for cleaning floors, carpets, or other surfaces. Household surface cleaning equipment, such as hot water floor scrubbers, typically utilizes cleaning liquids (such as water or detergent mixtures) to aid in the removal of stains and particulate matter. These devices heat the liquid in the water path via an internal heating element, and then spray the heated liquid from the outlet to achieve efficient surface cleaning. The heating element plays a crucial role in the cleaning process, its function being to heat the room-temperature liquid to a suitable temperature to enhance cleaning effectiveness. In traditional hot water floor scrubber designs, the heating element typically includes a heating element and a fluid channel, through which heat is transferred to the liquid flowing through the channel. The heating efficiency of the cleaning liquid directly affects the cleaning effect, especially when dealing with stubborn stains, where high-temperature liquids can significantly improve the efficiency of stain decomposition and removal. Utility Model Content

[0003] This disclosure relates to a fluid heater and a household surface cleaning device. The fluid heater includes a heating element, a pumping component, and an anisotropic valve. The heating element is configured to heat an internal fluid and has a fluid inlet and a fluid outlet, as well as a flow channel extending internally between the fluid inlet and the fluid outlet. The pumping component is configured to allow the internal fluid to flow substantially from the fluid inlet to the fluid outlet. The anisotropic valve is in fluid communication with the flow channel and is oriented in a generally directional direction of the flow channel to allow fluid within the heating element to flow out of the heating element, while simultaneously splitting the fluid into a first fluid and a second fluid, such that the first and second fluids have different flow rates.

[0004] In some implementations, the anisotropic valve includes a main flow channel and branch flow channels connected in parallel with the main flow channel. A first fluid flows through the main flow channel, and a second fluid flows through the branch flow channel. The first fluid impedance of the main flow channel is less than the second fluid impedance of the branch flow channel, ensuring a velocity difference. The extension direction of the main flow channel forms an angle greater than 0° and less than 90° with the longitudinal axis of the fluid inlet or outlet, and the extension length of the branch flow channel is greater than or equal to the length of the main flow channel. The anisotropic valve can be designed as a Tesla valve, with at least one or more arranged in series along the flow channel direction to optimize fluid diversion. Attached Figure Description

[0005] The accompanying drawings illustrate exemplary examples of this disclosure and, together with its description, serve to explain the principles of this disclosure. These drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this specification.

[0006] Figure 1This is a perspective view of a fluid heater for a household surface cleaning device, according to an example of this disclosure.

[0007] Figure 2 This is a cross-sectional view of a fluid heater for a household surface cleaning device, according to an example of this disclosure.

[0008] Figure 3 This is a schematic diagram of a household surface cleaning device according to an example of this disclosure. Detailed Implementation

[0009] The present disclosure will now be described in further detail with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the accompanying drawings.

[0010] It should be noted that, where there is no conflict, the examples and features in this disclosure can be combined with each other. The technical solutions of this disclosure will now be described in detail with reference to the accompanying drawings and examples.

[0011] Unless otherwise stated, the exemplary examples / exemplaries shown are to be understood as providing exemplary features of various details that provide some ways in which the technical concepts of this disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of the various examples / exemplaries may be additionally combined, separated, interchanged and / or rearranged without departing from the technical concepts of this disclosure.

[0012] In traditional hot water floor scrubbers, increasing the temperature of the sprayed hot water to enhance cleaning effectiveness faces several technical challenges. A major problem is that existing heating devices have limitations in heating efficiency and temperature uniformity, resulting in insufficient hot water temperature to meet the requirements of efficient cleaning. Specifically, in conventional designs, the liquid flow path within the heating element is short, the heating time is limited, and heat transfer is insufficient, leading to a lower output liquid temperature. Furthermore, the fluid flow within the channel is often monolithic, lacking an effective heat distribution mechanism, resulting in uneven heating of the liquid, with some areas being excessively hot while others are insufficiently hot. This unevenness not only reduces cleaning effectiveness but may also increase energy consumption and equipment operating costs. Existing technologies address these problems by increasing heating element power, improving water circuit insulation, extending heating time, or modifying the heating element structure. However, these methods still have limitations; for example, power increases are limited by energy consumption and equipment size, improvements in insulation performance are limited, and extending heating time may reduce cleaning efficiency. Therefore, the technical problem to be solved is to develop a fluid heater that can significantly improve liquid temperature and heating uniformity within a limited space while maintaining high operational efficiency.

[0013] This disclosure provides a fluid heater for household surface cleaning equipment, which enhances heating performance through an innovative fluid diversion design. The fluid heater includes a heating element, a pumping component, and an anisotropic valve. The heating element is configured to heat an internal fluid and has a fluid inlet and a fluid outlet, as well as an internal flow channel connecting the two. The anisotropic valve is in fluid communication with the flow channel and is arranged along the flow channel direction, diverting the fluid into a first fluid and a second fluid, and enhancing heat transfer efficiency through different flow velocities. This solution utilizes the diversion mechanism of the anisotropic valve to extend the fluid residence time within the heating element and optimize temperature distribution, thereby improving the temperature and uniformity of the output liquid to meet high-efficiency cleaning requirements.

[0014] The fluid heater disclosed herein significantly improves the heating performance and cleaning efficiency of a hot water floor scrubber through a flow-diverting mechanism using an anisotropic valve. Compared to existing technologies that rely on increasing power, improving insulation, or extending heating time, this disclosure incorporates a Tesla-valve-like water path within the heating body, causing the fluid to repeatedly divert and merge as it flows from the inlet to the outlet. This design effectively increases heating time within a smaller area by extending the water path, while simultaneously increasing the heated area through flow diversion, resulting in a more uniform liquid temperature and a significantly higher output hot water temperature, thereby enhancing the cleaning effect.

[0015] Other aspects of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of the disclosure. An embodiment of this disclosure will now be described in detail with reference to the accompanying drawings.

[0016] The embodiments described herein and the configurations shown in the accompanying drawings are merely exemplary embodiments of this disclosure. Modifications may be made in various ways to replace the embodiments and drawings herein at the time of filing this application.

[0017] Furthermore, the same reference numerals or markings shown in the accompanying drawings indicate elements or components that perform essentially the same function.

[0018] Similarly, the terminology used herein is for describing embodiments and is not intended to limit and / or constrain this disclosure. Unless the context clearly indicates otherwise, the singular forms “an,” “a,” and “the” also include the plural forms. In this document, terms such as “comprising,” “having,” etc., are used to specify the presence of a feature, quantity, step, operation, element, component, or combination thereof, but do not exclude the presence or addition of one or more other features, elements, steps, operations, components, or combinations thereof.

[0019] It is understood that although this document may use terms such as “first,” “second,” “third,” etc., to describe various elements, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and a second element may be referred to as a first element. The term “and / or” includes a combination of multiple related items or any one of multiple related items.

[0020] In the following detailed description, terms such as "front side", "rear side", "left side", and "right side" may be defined by the accompanying drawings, but the shape and position of the parts are not limited by these terms.

[0021] like Figure 1 As shown, the fluid heater 100 may include a heating element base 110 and an anisotropic valve 120. The heating element base 110 may have a channel 111, wherein the channel 111 may have two ends (i.e., a first end 1111 and a second end 1112). The heating element base 110 may have a fluid inlet 112 and a fluid outlet 113. The heating element base 110 may include two symmetrically arranged parts that can be combined to form the channel 111. The first end 1111 of the channel 111 may be near the fluid inlet 112, and the second end 1112 may be near the fluid outlet 113. It is conceivable that the assembled fluid heater 100 forms a closed channel 111 with two openings at the fluid inlet 112 and the fluid outlet 113.

[0022] Specifically, combined Figure 1 and 2 As shown, the fluid heater 100 is a fluid heater for a household surface cleaning device 200. Its heating element base 110 is configured to heat an internal fluid. A fluid inlet 112 and a fluid outlet 113 serve as the inlet for the fluid to be heated and the outlet for the heated fluid, respectively. A channel 111 forms a flow path extending along the interior of the heating element between the fluid inlet 112 and the fluid outlet 113. The means for pumping the fluid is configured to allow the internal fluid to flow substantially from the fluid inlet 112 to the fluid outlet 113.

[0023] like Figure 2As shown, the anisotropic valve 120 is in fluid communication with the channel 111 and is oriented in a general flow direction. It is used to allow the internal fluid within the heating element to flow out of the heating element, while simultaneously diverting the internal fluid to the main channel 1113 and the branch channel 1114. Along the fluid flow direction, the branch channel 1114 has a greater curvature than the main channel 1113, resulting in a lower fluid resistance in the main channel 1113 than in the branch channel 1114. Consequently, after the fluid is diverted, the flow velocities of the first fluid F1 in the main channel 1113 and the second fluid F2 in the branch channel 1114 are different. Specifically, the flow velocity of the first fluid F1 is greater than that of the second fluid F2. Thus, after the heating element starts heating, the fluid in the branch channel 1114 is heated for a relatively longer period, resulting in a higher temperature for the second fluid F2 than for the first fluid F1. After the first fluid F1 and the second fluid F2 converge, the fluid heat reaches equilibrium. Therefore, by adding a branch channel 1114, a better heating effect can be achieved with the same power and time, and the temperature can be kept even, avoiding insufficient heating.

[0024] like Figure 1 As shown, the heating element substrate can be composed of heating element substrate 1101 and heating element substrate 1102. When heating element substrate 1101 is mounted on heating element substrate 1102, the edges of heating element substrate 1101 and heating element substrate 1102 can be continuous, so that the assembled fluid heater 100 forms a uniform shape. The assembled fluid heater 100 can be of any shape, such as rectangular. In some embodiments, heating element substrate 110 can be detachable. The heating element substrate 1101 and heating element substrate 1102 of the fluid heater 100 can be made of any suitable material, such as ceramic.

[0025] The anisotropic valve 120 may have a positive flow direction. The device for pumping fluid may be used to guide fluid from the fluid inlet 112 to the fluid outlet 113 and may be configured on the heating element base 110.

[0026] In some examples, the fluid heater 100 may not be limited to a single channel 111. In some embodiments, the fluid heater 100 has multiple channels 111, each channel 111 having one end merged at a fluid inlet 112 and the other end merged at a fluid outlet 113. It is conceivable that in other embodiments, the heating element substrate 110 may have multiple fluid inlets 112 and / or fluid outlets 113, which are aligned with the respective ends of the channels 111.

[0027] The path of channel 111 can be of any shape (e.g., straight, zigzag, or serpentine). In some examples, such as... Figure 1As shown, channel 111 is zigzag-shaped relative to its two ends to increase the flow path length between the two ends for more thorough heating of the fluid. Channel 111 can have any length, depth, and width. The length, depth, and width can be on the order of micrometers to millimeters. In some embodiments, the depth and / or width of channel 111 can be substantially constant. Alternatively, the depth and / or width of channel 111 can vary. The depth and / or outer width of anisotropic valve 120 can be complementary to the depth and / or width of channel 111, such that anisotropic valve 120 fits tightly to channel 111. Anisotropic valve 120 can have any inner width. The inner width W3 can be on the order of micrometers to meters. In some embodiments, the inner width of anisotropic valve 120 can vary. It is conceivable that the inner width of anisotropic valve 120 can be adjusted according to the fluid passing through anisotropic valve 120 to optimize the velocity difference between the first fluid F1 and the second fluid F2.

[0028] like Figure 1 As shown, the cross-sectional shape of channel 111 can be circular. In some embodiments, channel 111 can have any cross-sectional shape. Along the general flow direction, one, two, or more anisotropic valves 120 can be provided, with multiple anisotropic valves 120 arranged in series to enhance fluid diversion and heating effects.

[0029] The fluid heater 100 can have any suitable means for pumping fluid from the fluid inlet 112 to the fluid outlet 113 (e.g., a peristaltic pump, etc.). The means can be configured at the fluid inlet 112 of the heating element base 110 to pump ambient temperature fluid into the fluid inlet 112. In some examples, the fluid heater 100 can be configured to be connected to a peristaltic pump. The peristaltic pump can be connected to the fluid inlet 112 of the heating element base 110 such that the peristaltic pump pushes fluid into the fluid heater 100, through the channel 111 and the anisotropic valve 120, and then out from the fluid outlet 113. In some embodiments, the peristaltic pump can be connected to the fluid outlet 113 and achieve the same effect. The peristaltic pump can be battery powered or powered via an AC / DC adapter. The peristaltic pump, as a pumping component, ensures the basic flow of internal fluid from the fluid inlet 112 to the fluid outlet 113.

[0030] The anisotropic valve 120 may be similar to the Tesla valve found in the prior art. Figure 2An example cell of an anisotropic valve 120 is shown. The angle α and size of the fins 121 within the anisotropic valve 120 affect the forward and reverse flow directions. For example, the cross-section changes depending on the angle, and more turbulence may be generated at higher angles. The anisotropic valve 120 can allow fluid to flow in one direction, such as the forward flow direction from fluid inlet 112 to fluid outlet 113, and accelerate the fluid flow; while simultaneously inhibiting flow in the opposite direction, such as the reverse flow direction from fluid outlet 113 to fluid inlet 112. Figure 1 and Figure 2 As shown, multiple anisotropic valves 120 arranged in series can be positioned within the channel 111 such that the fluid flow direction is from the fluid inlet 112 to the fluid outlet 113. In such an embodiment, the means for pumping the fluid provides a driving force for the fluid in the positive flow direction and guides the fluid through the anisotropic valves 120, which are oriented in a generally flow-channel direction, into the positive flow direction. The anisotropic valves 120 can be positioned within the channel 111 such that the positive flow direction is from the fluid inlet 112 to the fluid outlet 113. It is conceivable that the orientation of the anisotropic valves 120 within the channel 111 can affect the flow time of the fluid within the heating element, thereby ensuring that the flowing fluid is sufficiently heated within the channel 111. Specifically, the anisotropic valve 120 includes a main flow channel 1113 and a branch flow channel 1114 connected in parallel with the main flow channel 1113. A first fluid F1 flows through the main flow channel 1113, and a second fluid F2 flows through the branch flow channel 1114. The impedance of the first fluid F1 in the main flow channel 1113 is less than the impedance of the second fluid F2 in the branch flow channel 1114, resulting in a higher flow velocity of the first fluid F1 than that of the second fluid F2. At the fin tip 123, the fluid is split into the fluid in the main flow channel 1113 and the fluid in the branch flow channel 1114; and the fluids in the main flow channel 1113 and the branch flow channel 1114 are mixed again at the fin tip 122 along the fluid flow direction. When multiple anisotropic valves 120 are connected in series, the repeated splitting and merging of the fluid as it flows from the fluid inlet 112 to the fluid outlet 113 ensures uniform fluid temperature. This extends the heating time within a smaller area by lengthening the water path. Furthermore, the extension length of the branch channel 1114 is greater than or equal to the extension length of the main channel 1113, thereby improving fluid heating efficiency and effectiveness. In one example, the extension direction of the main channel 1113 forms an angle greater than 0° and less than 90° with the longitudinal axis of the fluid inlet 112, and also forms an angle greater than 0° and less than 90° with the longitudinal axis of the fluid outlet 113, ensuring smooth flow branching. The anisotropic valve 120 can be positioned within the channel 111 to allow at least a portion of the fluid to flow unidirectionally from the fluid inlet 112 to the fluid outlet 113. In some embodiments, all fluid entering the device 100 flows out of the device 100 through the anisotropic valve 120. The anisotropic valve 120 can operate with low fluid flow rates.

[0031] like Figure 3 As shown, the fluid heater 100 can be configured onto the fluid distribution system of a household surface cleaning device 200 to form a complete household surface cleaning device 200. The household surface cleaning device 200 includes an agitator 210, a suction nozzle (not shown), and a liquid dispenser 220. The agitator 210 is used to scrub the surface to be cleaned in conjunction with a cleaning medium; the suction nozzle is adjacent to the agitator 210 and in fluid communication with a recovery storage unit (not shown) for removing contaminated liquid from the agitator 210 and the surface to be cleaned; the liquid dispenser 220 is used to provide cleaning liquid to the agitator 210 or the surface to be cleaned in its vicinity. In some examples, the fluid distribution system may have an inlet and an outlet. When the fluid heater 100 is placed within the fluid distribution system, the inlet and outlet of the fluid distribution system are located near the outlet of the cleaning liquid storage unit (not shown) and the fluid inlet 112 of the heating element base 110, respectively. It is understood that when fluid enters the device 100 through the inlet of the fluid distribution system, at least a portion of the fluid enters the fluid inlet 112 of the heating element base 110 and enters the channel 111. Similarly, when fluid flows out from the fluid outlet 113 of the heating element base 110, at least a portion of the fluid flows out from the outlet of the fluid distribution system. The fluid distribution system can have any number of inlets and outlets. The number of inlets and outlets of the fluid distribution system can correspond to the number of fluid inlets 112 and fluid outlets 113 of the heating element base 110. The fluid heater is located between the liquid distributor 220 and the agitator 210, and can be selectively activated to supply heated liquid to the agitator 210 when the surface household surface cleaning device 200 is in operation.

[0032] The fluid distribution system is used to store cleaning liquid and is capable of distributing the stored cleaning liquid to the agitator 210. For example, the fluid distribution system includes a cleaning liquid storage section, a cleaning liquid storage section, and a distribution channel. The distribution channel is connected to the cleaning liquid storage section and the fluid inlet 112 to provide the cleaning liquid in the cleaning liquid storage section to the fluid inlet 112, and after being heated by the fluid heater 100, it is distributed to the agitator 210.

[0033] In this disclosure, the cleaning liquid storage section is formed in the shape of a box to store cleaning liquid. In one embodiment, the cleaning liquid may be purified water or a mixture of water and cleaning agent. A pump device (i.e., a device for pumping fluid) is provided on the distribution channel so that the cleaning liquid in the cleaning liquid storage section is pressurized and supplied to the fluid heater 100, heated, and then output through the outlet of the fluid distribution system, and evenly distributed on the outer peripheral surface of the stirring member 210.

[0034] The fluid heater 100 configured into the fluid distribution system can be detachable and replaceable. It is conceivable that the assembled fluid distribution system and fluid heater 100 can be lightweight and portable, with good interchangeability.

[0035] An exemplary embodiment relates to a method of using a fluid heater 100. Embodiments of the fluid heater 100 may include a heating element base 110, an anisotropic valve 120, and means for pumping fluid. The heating element base 110 may have a channel 111 having two ends. The heating element base 110 may have a fluid inlet 112 and a fluid outlet 113. The heating element base 110 may be mounted on the heating element base 110, with the fluid inlet 112 near the first end 1111 and the fluid outlet 113 near the second end 1112. The anisotropic valve 120 may be positioned within the channel 111, oriented in a generally flow direction, diverting internal fluid to a first fluid F1 and a second fluid F2, achieving different flow velocities through the main channel 1113 and the branch channel 1114. The anisotropic valve 120 may have a forward flow direction and a reverse flow direction. A device for pumping fluid is used to guide fluid from a fluid inlet 112 to a fluid outlet 113 and may be configured onto a heating element base 110. The method may involve activating the device for pumping fluid. Activation of the device for pumping fluid may include, but is not limited to, turning on a peristaltic pump. For example, in some embodiments, the device for pumping fluid is a peristaltic pump configured at the fluid outlet 113 of the heating element base 110, activating the peristaltic pump to draw fluid into the fluid inlet 112 of the device 100, through channel 111 and anisotropic valve 120, and then out of the fluid outlet 113 of the device 100. The method may involve allowing fluid to enter the fluid inlet 112 of the device 100 and through channel 111. It is understood that the fluid is a cleaning liquid supplied by the liquid supply tank of the surface household surface cleaning device 200, which is then distributed to the agitator 210 after being shunted and heated by the anisotropic valve 120.

[0036] The above description of the examples in this disclosure is for illustrative purposes only and is not intended to be exhaustive or to limit the disclosure to its precise form. Those skilled in the art will understand that many modifications and variations are possible based on the above disclosure.

[0037] Certain portions of this description use notation to represent algorithms and information operations to illustrate examples of this disclosure. These algorithmic descriptions and representations are commonly used by those skilled in the art of data processing to effectively communicate the substance of their work to others skilled in the art. While these operations are described functionally, computationally, or logically, they are understood to be implemented through computer programs or equivalent circuits, microcode, or similar programs. Furthermore, it is sometimes convenient to arrange these operations as modules without loss of generality. The operations and their associated modules may be embodied in software, firmware, hardware, or any combination thereof.

[0038] Any step, operation, or process described in this disclosure may be performed or implemented by one or more hardware or software modules, alone or in combination with other devices. In one example, the software module is implemented by a computer program product including a computer-readable medium containing computer program code executable by a computer processor to perform any or all of the described steps, operations, or processes.

[0039] Embodiments of this disclosure may also relate to means for performing the operations described herein. Such means may be specifically constructed for the desired purpose, and / or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. This computer program may be stored in a non-transitory, tangible, computer-readable storage medium, or any type of medium suitable for storing electronic instructions, which may be connected to a computer system bus. Furthermore, any computing system mentioned in the specification may include a single processor or may employ a multi-processor architecture to enhance computing power.

[0040] Embodiments of this disclosure may also relate to products generated by the computational processes described herein. Such products may include information generated by the computational processes, wherein the information is stored on a non-transitory, tangible, computer-readable storage medium, and may include any example of the computer program products or other combinations of data described herein.

[0041] Finally, the language used in this specification has been chosen primarily for readability and instructional purposes and may not have been chosen to define or limit the subject matter of this disclosure. Therefore, the scope of this disclosure should not be limited to this detailed description, but rather to any claims made on this basis. Thus, the illustrative disclosure of this specification is intended to illustrate, and not limit, the scope of this disclosure.

Claims

1. A fluid heater for use in household surface cleaning equipment, characterized in that, include A heating element for heating an internal fluid, the heating element including a fluid inlet and a fluid outlet, and a flow channel extending inside the heating element between the fluid inlet and the fluid outlet; Pumping components are used to make internal fluid flow substantially from the fluid inlet to the fluid outlet; An anisotropic valve, in fluid communication with the flow channel, is used to allow internal fluid within the heating body to flow out of the heating body; the anisotropic valve is oriented in approximately the direction of the flow channel and diverts the internal fluid to a first fluid and a second fluid, such that the flow rates of the first fluid and the second fluid are different.

2. The fluid heater according to claim 1, characterized in that, The anisotropic valve includes a main flow channel and a branch flow channel connected in parallel with the main flow channel. The first fluid flows through the main flow channel, and the second fluid flows through the branch flow channel.

3. The fluid heater according to claim 1, characterized in that, The anisotropic valve includes a first fluid resistance along the main flow path and a second fluid resistance along the branch flow path, wherein the first fluid resistance is less than the second fluid resistance.

4. The fluid heater according to claim 1, characterized in that, At least one anisotropic valve is provided along the general flow path direction.

5. The fluid heater according to claim 1, characterized in that, Along the general flow path, multiple anisotropic valves are provided, and the multiple anisotropic valves are connected in series.

6. The fluid heater according to claim 2, characterized in that, The fluid inlet includes a longitudinal axis, and the extension direction of the main flow channel forms an angle greater than 0° and less than 90° with the longitudinal axis.

7. The fluid heater according to claim 2, characterized in that, The fluid outlet includes a longitudinal axis, and the extension direction of the main channel forms an angle greater than 0° and less than 90° with the longitudinal axis.

8. The fluid heater according to claim 2, characterized in that, The extension length of the tributary is greater than or equal to the extension length of the main channel.

9. The fluid heater according to claim 1, characterized in that, The anisotropic valve includes a Tesla valve.

10. A household surface cleaning device, characterized in that, include: A stirring element, used in conjunction with a cleaning medium to scrub the surface to be cleaned; A suction nozzle is provided, wherein the agitator is adjacent to the suction nozzle, the suction nozzle is in fluid communication with the recovery storage section, and is used to remove contaminated liquid from the agitator and the surface to be cleaned; A liquid dispenser for supplying cleaning liquid to a stirring element or a surface to be cleaned in the vicinity of the stirring element; as well as The fluid heater as claimed in any one of claims 1-9, wherein the fluid heater is located between the liquid distributor and the agitator, and the fluid heater may be selectively activated to provide heated liquid to the agitator when the surface cleaning device is in operation.

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