Hot water supply process and device

Abstract

HOT WATER SUPPLY PROCESS AND DEVICE. Process for preparing the drink by supplying hot water to the hot drink dispenser through a liquid transport circuit (2), comprising: - a heating element (8) which has a heating resistance; - a pump (14); the process is such that, after activation by a user of a control medium (7), the liquid is heated, feeding the heating resistance to a pre-defined average electrical power, the liquid is heated and, as long as the measured temperature is higher than a first predetermined temperature limit (Tl), the liquid for the drink is circulated in this heating element (8), with a constant nominal flow, between 0.5 and 1.5 cl / second, and the average electrical power of the heating resistor (12) being such that the ratio of this power expressed in watts divided by the nominal flow in centiliters is greater than 2000.

Description

1 / 25 PROCESS AND DEVICE FOR SUPPLYING HOT WATER The present invention relates generally to a process and a device for supplying hot drinking water. There are known devices that allow you to obtain very hot water in small quantities (as opposed to water heaters that provide large quantities of moderately hot water), such as one to two liters at most, such as hot beverage dispensers, coffee machines, or electric kettles. For example, a device for preparing a beverage by supplying hot water, comprising: is known from patent document GB 2 394 215 A: - a liquid transport circuit; an electronic control unit equipped with an electrical power supply and a means of controlling the device; The transport circuit comprising: - a liquid heating element, comprising a heating resistor and arranged in series with a pump adapted to ensure liquid circulation in the circuit at a determined flow rate, the pump and the heating element being electrically powered and controlled independently of each other by the control unit. This prior art device comprises a storage reservoir for liquid that is permanently heated by a heating element to a temperature between 50 and 60°C. Once the user commands a quantity of hot water, the heating element is then electrically supercharged to... The device heats the water, which has already been pre-heated, to a temperature higher than boiling point, after which the pump is activated to release the water at a temperature above 60°C. This device allows for the rapid release of hot water, but has the disadvantage of constantly consuming the energy required for preheating. In the case of electric kettles, the main drawback is the time it takes for the appliance to heat the water, giving the user the impression that the appliance is inactive. Another drawback is that the user tends to heat more water than necessary, which leads to a waste of time and energy. In the case of hot beverage dispensers or "espresso" type coffee machines, a quantity of water or a mass of aluminum is kept continuously heated, which generates unnecessary energy consumption. Furthermore, the waiting time before the hot liquid starts to be released is relatively important and usually exceeds 5 seconds, thus lengthening the time it takes to obtain the beverage. A coffee machine of the type previously described, but eliminating the need to preheat a large quantity of water, is, on the other hand, described in US patent document 6,000,317. This machine includes a filter that receives coffee and is located at the outlet of the water transport circuit. To function, the water is heated very rapidly (for example, until the percolation temperature of the coffee is reached, between 92°C and 96°C, but which can exceed 100°C due to the back pressure created by the coffee) at high pressure, and The water is sent to the filter at a flow rate that is a function of the pump, and the lower the flow rate, the greater the pressure drop due to the coffee grounds in the filter. Therefore, this machine does not allow the dispensing of hot water (temperature above 70°C, but preferably below 90°C) at a high, constant flow rate, such as greater than 0.5 cl per second. The problem presented, then, is how to supply hot water, according to a process and device that allows for the rapid release of a quantity of hot, but not boiling (70°C minimum and preferably less than 90°C) water, at least sufficient to fill a container, such as a cup (12 to 40 cl), in order to prepare a beverage, such as tea, without preheating the appliance and / or a volume of water and without the need for very strong heating. The term preheating refers to any heating operation prior to the user switching on the appliance, and a very high power should be considered to be greater than 3.5KW, without exceeding this amount, as this would present difficulties for the domestic electrical network normally designed for small household appliance use. To release very quickly, naturally, on the one hand, it is understood to begin releasing the heated liquid at the desired flow rate in at least less than 5 seconds after a command action from the user on the device, and, on the other hand, to release a liquid volume of at least 12cl at 70°C in less than 25s. It should be noted that throughout the description of the invention abbreviation "cl" designates the unit centiliter. what corresponds to 10' 2 dm 3 (ten to the power of minus 2 cubic decimeters). For this purpose, the process, according to the invention, of preparing a beverage by supplying hot water through a liquid transport circuit, comprising a heating element, having a heating resistor and a pump arranged in series with the heating element and adapted to ensure the circulation of liquid in the circuit, is such that, after activation by a user of a control means: The liquid is heated by supplying the heating element with a pre-defined average electrical power, and the temperature of the heated liquid (T) is measured. - the liquid is kept heated and, provided that the measured temperature (T) is higher than a first predetermined temperature limit (Tl), the liquid is circulated to the beverage in this heating element, with a constant nominal flow rate determined (D) less than 2 cl / s, preferably between 0.5 cl / s and the average electrical power of the heating resistance being such that the ratio (R) of this power expressed in Watts divided by the constant nominal flow rate expressed in centiliters per second is greater than 2000. Preferably, this ratio (R) between this predefined average electrical power and the determined constant nominal flow rate is predefined, at a constant and predefined value between 2000 and 4000. Thanks to this process, therefore, it is possible to solve the problem presented, releasing it quickly. a specified quantity of hot liquid at over 70°C without having to resort to continuous preheating of the liquid to be released. Thanks to the above reason, the continuous heating process of the liquid to be released from the invention can be applied, powering the device with a power supply available on domestic public networks worldwide (for example, European network at 220V and 16A and American network at 110V). Thus, the average electrical power of the heating element used for the application of the process and device of the invention is chosen to be less than 3500W, this value being measurable when the element is electrically powered by a previously mentioned domestic public network. According to the invention, the pump and the heating element are controlled independently of each other by an electronic control unit equipped with an electrical power supply and a control means. The process is activated by a single initial command given by the user to the control means, and upon receiving this command, an electronic control unit generates all the actions of the process. Thus, the heating of the liquid is activated only after the user acts on the control mechanism, and then the circulation at a fixed, predetermined flow rate of heated liquid begins only after the liquid temperature has reached the first temperature limit. It is also possible to cut off the power supply to the heating element, provided that the measured temperature T The flow rate exceeds a second limit T2, maintaining liquid circulation, and the fluid circulation is cut off when the desired amount of liquid has been supplied to the user. This allows for the continuous release of heated liquid without it exceeding its vaporization temperature. The released liquid is poured into a container, preferably a cup. The invention also provides a beverage preparation device by supplying hot water, comprising a heating device, as previously defined, wherein the pump and heating element are such that the electrical ratio (R) of the average electrical power (P) of the heating resistance, expressed in Watts, divided by the nominal liquid flow rate (D), which can be ensured by the pump in the transport circuit and expressed in cl / s, is greater than 2000. This device also addresses the problem presented and allows the application of the invention process. Furthermore, it can incorporate a particular heating element, which allows for the rapid heating of a volume of liquid, thanks to a heating resistor screen-printed directly onto one face of the complementary element. The thermal power produced by the screen-printed resistor is directly transmitted through the complementary element to the liquid within the heating element, between the body and the complementary element. Advantageously, it can be done so that, in the control process, after cutting off the power to the heating element, while maintaining the circulation of the liquid, feeds itself heating element, since what If the measured temperature falls below a third lower temperature limit (below the second and above the first), the heating element's cut-off / feedback cycle restarts, as appropriate, until the desired amount of liquid has been supplied to the user. This feature allows for the continuous release of hot water at a determined flow rate, that is, at a fixed and constant flow rate, such that the desired quantity of liquid is not reached. This flow rate is preferably less than 2 cl / s, ideally between 0.5 and 1.5 cl / s. Furthermore, in order to prevent the user from being surprised by the lack of liquid release after their command (see above a wait of less than 5s), before the liquid temperature T has reached the first temperature limit Tl, the liquid is circulated to the beverage in the heating device at a minimum flow rate (Dmin) lower than the nominal flow rate D. The specific dimensioning of the pump and the heating element, according to the invention, ensures that, when these are powered, the heating power is always sufficient to allow the liquid circulating at a constant flow rate to be heated beyond the first temperature limit. Therefore, there is no need to interrupt the flow to avoid releasing a liquid (water) at a temperature lower than the temperature of the first limit. This allows you to have an uninterrupted flow and always have hot water above the second temperature limit. Thus, after heating a portion of liquid beyond the first limit temperature, it is certain that when the The transport circuit is fed with the liquid at a determined flow rate, and when the resistor is energized, the liquid exiting the device is heated until it reaches at least a certain temperature (usually above 70°C). Thanks to this feature, the device of the invention allows for the rapid dispensing of a heated liquid, this dispensing only being interrupted at the user's command via the control mechanism or according to a programmed quantity. Considering that the heating power and fixed flow rate allow reaching the predefined ratio of 2000, this eliminates the need to control the resistance proportionally. Thus, the heating element is controlled entirely or partially by the control unit, which is particularly economical compared to a proportional regulation solution. Advantageously, the device includes a temperature sensor connected to the control unit and arranged to capture a temperature on a circuit section located between the heating element and the free end. It should be noted that "located between the heating element and the free end" means that the sensor can be positioned on the heating element and also downstream of the heating element, between that element and the free end. This temperature sensor is preferably a thermistor with a Negative Temperature Coefficient (NTC), but it can also be a thermistor with... positive temperature coefficient (CTP). Other features and advantages of the invention will become clear from the description that is, in fact, given below, by way of indication and in no way limiting, with reference to the attached drawings, in which: Figure 1 represents a perspective view, before, of a liquid heating device, according to one embodiment of the invention; Figure 2 represents a rear perspective view of the device in Figure 1; Figure 3 represents an exploded perspective view of the heating element of the invention's device; Figure 4 represents a cross-sectional view of an example of a shut-off valve of the invention's device; Figure 5 represents a schematic view of the control circuit of the device of the invention; Figure 6 represents a view of a heating cycle performed according to the process of the invention and with the device of the invention. As previously announced, the invention relates to a device for supplying hot liquid, this liquid generally being water previously placed at room temperature of approximately 20°C to 25°C (conditions for which the device is particularly well-suited). The hot liquid supply device 1 shown in figures 1 and 2 comprises a liquid transport circuit 2 and an electronic control unit, allowing it to collect commands from the user. The control unit generates information about the device's operation and commands the device. Thus, the control unit generates the application of the invention's process. Considering that the device of the invention serves to prepare beverages by supplying hot water, the parts of the transport circuit 2 that are in contact with the heated liquid, i.e., the hot water, are made of food-grade material(s), such as stainless steel, plastic (e.g., glass-filled PA). The heated water is put into circulation, according to the fact that the process of the invention is released into a container, such as a cup, and is ready to be drunk by the user. The transport circuit 2 has a liquid feed end 3 connected to a liquid reservoir 15 via a shut-off valve (described in figure 4), and another free end 4 to release the heated liquid to a user. Thanks to its reservoir, the device can operate without needing to be connected to an external water supply. A cup was depicted below the free end 4 of the transport circuit 2 to receive the heated and released liquid. The circuit also includes a liquid heating element 8 arranged in series with and downstream of a pump 14. This pump 14 is adapted to ensure the circulation of liquid in circuit 2 at a fixed flow rate determined D, that is, a constant flow rate. The positioning of pump 14 between reservoir 15 and heating element 8 This allows the pump to be fed with warm water, which increases its lifespan. On the other hand, thanks to this position, the liquid in the heating element is always under slight superpressure, since it is placed downstream of the pump. This slight superpressure allows for a momentary heating temperature close to the boiling point, without the risk of massive steam formation in the circuit. The control unit is electrically powered by a power cable not shown and connected to the sector. As visible in Figure 5, this unit contains an electronic circuit connected to a temperature sensor C located on the heating element, near the heated liquid outlet (i.e., downstream of the heating resistor 12 of the heating element 8). The heating element 8 shown in figure 3 comprises a main body 9, associated with a complementary element 10 that covers one face of the main body 9 to define a liquid circulation volume, this complementary element 10 having a heating resistance 12 screen-printed on its face opposite 13 to that in front of the main body 9. The main body 9 has a lower thermal inertia than aluminum, and the complementary element has a heating element screen-printed on its opposite face 13 to that facing the main body. Thermal inertia (Ith) refers to the ability of a body to store more or less heat, which can be expressed as the product of its mass density (ρ) and its specific heat capacity (cp). Ith = px cp According to the invention, the main body is a kind of "thermal insulator" because, during a heating phase, it consumes far fewer calories than the circulating liquid, due to its low thermal inertia. For this reason, this main body 9 is made of plastic. Advantageously, the complementary element exhibits a strong transverse thermal conductivity coefficient, for example, greater than 40. By transverse thermal conductivity coefficient (cth), we mean the ratio of the thermal conductivity coefficient (X) of the complementary heating element material divided by its thickness (e), expressed in millimeters. Cth = X / e In other words, the complementary element transmits the heat energy from the heating element to the liquid very quickly by conduction, either because the thickness of the complementary element is reduced, on the order of 3 mm for a material like aluminum with a high coefficient of conductivity, or because the thickness is very reduced, on the order of millimeters, for a material with a lower coefficient of conductivity like stainless steel. Incidentally, the fact that the heating element is of the screen-printed type, combined with its good transverse thermal conductivity coefficient, means that the complementary heating element also exhibits low thermal inertia, reducing energy losses. Now, this type of heating element 8, which has a screen-printed heating element 12, allows for a... Uniform heating over a large surface area in front of the liquid increases its overall thermal conductivity efficiency. In other words, the heating element 8 comprises a main body 9 that is relatively thermally insulating, and which is covered by a complementary element 10 that heats up rapidly. This complementary element 10 therefore transmits heat energy to the liquid circulating in the space separating it from the main body 9. Due to the high heat transfer coefficient by conduction of the complementary element, most of the energy dissipated by the screen-printed resistance is transmitted to the circulating liquid, rather than accumulating in the complementary heating element 10. Similarly, the main heating body 9 has low thermal inertia, so it stores a small amount of energy from the complementary heating element 10. It follows that the liquid receives the heat energy from the screen-printed resistor 12 very quickly and almost entirely, so that the heating of the liquid is almost instantaneous. Similarly, the main body practically does not participate in the heating phenomena of the liquid, so that when the device is not working, it is not necessary to supply any amount of energy to maintain a sufficient temperature. In other words, the consumption of the heating device outside of the actual heating phases is zero. In conclusion, the heating phase of heating element 8 is extremely fast, from the... The device can be used immediately, as the heating element does not require a significant amount of energy to reach operating temperature. Therefore, there is no need for a preheating phase before the control mechanism 7, which is an on / off button, is activated. In practice, the heating element 8 can have different geometries. Thus, in a first embodiment represented in figure 3, the central body is cylindrical, and receives on its outer face 11 the complementary heating element 10 which forms an annular sleeve. In another embodiment, the central body can be flattened, and then a flattened heating element can be added. To increase the effectiveness of the device, it can be foreseen, as is the case in figure 3, that the main body 9 has a groove that allows defining, with the complementary element 10, a channel for the circulation of the liquid, thus increasing the path traveled by the liquid in the middle of the heating device, and therefore its capacity to receive heat energy. For the same purpose, the screen-printed resistor 12 can be advantageously located vertically in the liquid circulation channel. In practice, when the heating element is generally cylindrical in shape, the groove is helical 21 as in figure 3, whereas when the central heating body is flattened, the groove can then be spiral in shape. The helical groove 21 is formed by a helix 24 that coils along the face 11 of the body 9. In the same spirit, the main heating element 9 is preferably hollow, so as to further limit its mass, and therefore its thermal inertia. The temperature sensor C is adjusted on the complementary element. Due to the fact that the complementary element 10 has strong transverse conductivity and the main body 9 and the complementary element 10 have weak thermal inertia, the electrical and / or electronic regulation is particularly dynamic, almost instantaneous, causing the liquid to exit at a more stable temperature with minimized energy consumption. Figure 3 illustrates one embodiment of heating element 8 in which this heating element is cylindrical. In this case, the heating element 8 comprises a central main body 9 associated with a complementary heating element 10 in the form of a cylindrical sleeve. The space defined between the outer face 11 of the central main body 9 and the inner face of the sleeve 10 forms the hollow cylindrical volume for liquid circulation. In the illustrated form, the outer face of the main body 9 has a helical groove 4 that allows the sleeve to define a fluid path around the main body. However, in other embodiments, not shown, the outer face of the main body 9 may be completely cylindrical, so as to define with the sleeve a circulation volume of constant thickness, extending along the cylinder. Other variants may be considered, without departing from the scope of the invention. In practice, the The main central body 9 is connected to a cold water supply, that is, to the water outlet of the pump. This inlet is connected to the outer face (face 11 of the main body) by a roughly radial channel 19, which opens onto the outer face 11. The main central body 9 is preferably made of plastic material, or more generally of a material that has a weak thermal inertia Ith, in any case less than that of aluminum on the order of 2.30, so as to store only a small part of the heating energy. As a material capable of being very convenient in making the main body 9, according to the invention, one can mention polyamide (Ith = 1.9), polyacetal (Ith = 2), polypropylene (Ith = 1.6), polysulfone (Ith = 1.4) or polycarbonate (Ith = 1.5), polyphenyl sulfone PPS. As illustrated in Figure 3, the main central heating body 9 has a central cavity 20, designed to further reduce its weight and therefore its thermal inertia. In this example, groove 21 has a depth of approximately 3mm and a width of approximately 8mm. This groove 21 has a helical geometry, with a pitch of approximately 9mm. In other words, the depth is less than the width, so as to "spread" the liquid against the complementary heating element 10 and thus favor the transfer of calories. Preferably, the sleeve or complementary element 10 is manufactured in such a way as to exhibit a high coefficient of transverse thermal conductivity and low inertia. thermal. The thickness of sleeve 10 is reduced to a minimum depending on the base material to decrease thermal inertia and increase conduction phenomena. Among the materials that give good results in terms of thermal properties, copper, stainless steel, aluminum, or glass can be mentioned. It is important that sleeve 10 allows the deposition of a screen-printed heating element 12. The process of making heating tracks consists of screen-printing one or more layers of insulating material, then a layer of conductive paste, following a particular path, a layer to form contact cables, and finally one or more layers of insulating material. The available power can be in the order of 2000W to 3000W. This electrical resistance 12 therefore forms a belt which, in the illustrated form, is adjusted in the form of offset transverse circles along the same longitudinal line: the entire inner surface of the sleeve forms a heating plate against which the grooves force the liquid to pour. If desired, the screen-printed resistance can be helical, and be located vertically within the channels defined by the groove 21 of the main heating body 9. In this case, the heating efficiency and its speed are improved. Thus, for a stainless steel sleeve / complement 10 having an outer diameter of approximately 4.5 mm, the thickness of the sleeve 10 can advantageously be between 0.5 and 1 mm, preferably between 0.8 and 1 mm. Its transverse thermal conductivity coefficient cth is then of approximately 60. The advantage of stainless steel is its corrosion resistance and its High-temperature maintenance facilitates the creation of flat heating elements. The use of a complementary aluminum sleeve / element 10 is considerable, but with heating elements on polyimide support and pastes at lower cooking temperatures. For example, for an aluminum sleeve with a thickness of approximately 3 millimeters, allowing for screen-printed heating elements, its thermal conductivity coefficient cth is approximately 70. In practice, the circulation of water in the routing along the outer face 11 of the main body 9 is done by means of the pump, but this circulation could also be done, without a pump, by gravity; however, the pump has the advantage of providing a constant flow rate. Usefully, a temperature sensor C is used, such that a resistor CTN is brought against the complementary heating element and is connected to the electronic control unit 5 in Figure 5. When first starting up with a cold heating device, the regulation controls a rapid preheating, on the order of 2 to 3 seconds, before the start of water circulation. This particularly rapid preheating, almost imperceptible to the user, is due to the very low overall thermal inertia of the device and its efficiency in transferring heat primarily to the water contained in the circuit. In practice, measurements taken with this type of heating device (equipped with a 2600W electric heating element) allow for heating approximately 21 liters of water. a temperature between 70 and 80°C in just 25 seconds. The preheating phase, which is only optional, is particularly short, since the flow can begin no later than approximately 3 seconds after the heating device is switched on. It stands out from the preceding that the heating element 8 of the device, according to the invention, presents multiple advantages, and notably that of having a particularly low thermal inertia. It follows, therefore, that the water circulating in the device heats up almost instantaneously when the heating element 12 is placed under tension. When resistor 12 is de-energized, the heating element cools down rapidly, thanks to its low thermal inertia. This protects the surrounding environment from overheating and also facilitates the regulation of the output temperature. The presence of the screen-printed heating element also ensures a distribution of heating power over a larger surface area compared to existing solutions, in order to optimize heat transfer. Figure 4 represents an example of a shut-off valve 16 installed on a lower part of the reservoir. This valve 16 is mounted slidingly on the lower part of the reservoir, so that in one position it blocks the passage of fluid 17 and in another position it conceals that same passage. The connection between the reservoir and the liquid supply end is made by fitting two male / female pipes together. The valve comprises a conical sealing section and a stem 22 that rests against a complementary part of the feed end when the reservoir is connected to the feed end. When the reservoir 15 is connected to the feed end 3, the valve stem 22 rests against the feed end 3, thus forcing the valve to move from its closed position to its open position. Conversely, when the reservoir is separated from the feed end 3, the valve rotates to its closed position, either by gravity and / or under the pressure of a spring acting on the valve, or by the pressure of the liquid in the reservoir. Thus, the shut-off valve 16 automatically opens the fluid passage 17 from the reservoir 15 to the pump 14 when the reservoir 15 is connected to the feed end 3 and automatically shuts off this passage 17 when the reservoir 15 is disconnected from the feed end 3. Eventually, a filter 18 may be placed at the inlet of the feed end in order to prevent polluting particles from entering the liquid transport circuit 2. Figure 5 represents a connection diagram of the device of the invention. The electronic and / or electrical control unit 5 comprises a control means 7 which is a start-up button possibly coupled with a means of pre-selecting the volume of liquid to be dispensed. In the event that the device of the invention comprises a means In addition to pre-selecting the volume of liquid to be dispensed, this is preferably a manually adjustable time command generated by the control unit 5. Indeed, considering that the flow rate released by the device's pump is a fixed (constant) flow rate, then the volume of liquid actually dispensed depends solely and directly on the operating time of the pump at that fixed flow rate. For example, by setting the timer to 7 seconds, the pump will then be powered for 7 seconds, allowing it to release approximately 7 liter of hot water at a constant flow rate. The control unit is also connected to a temperature sensor C and has two switches that act respectively on the power supply of the heating element 12 and the pump 14. In this way, pump 14 and heating element 8 are electrically powered and controlled independently of each other by control unit 5. A generator G (symbolizing the electrical power supply to the sector) provides electrical energy to the heating element 12 and the pump 14 to which it is connected. The device's control process is triggered by a single initial command issued by the user on the device's control medium 7. Upon receiving this command, the electronic control unit generates the set of process actions. The operation of this circuit and the management of heating and flow by the electronic control unit are described in Figure 6. Figure 6 represents a heating cycle. carried out according to the invention process with device of the invention. The x-axis represents the time scale in seconds. The left-hand y-axis, numbered from 0 to 120°C, corresponds to the temperature curve in degrees Celsius indicated by the CTN over time. This curve is actually the representative curve of the temperature of the liquid that passed through heating element 8 as a function of time. Curve D corresponds to the instantaneous liquid flow rate generated by the pump as a function of time. The numerical value The curve corresponding to D is indicated on the ordinate axis by a numbered line from 0 to 1.2 cl / s. In this example of operation, the fixed flow rate of the operating pump is regulated in 1 / 2 cc per second. The third curve, denoted with P, is the curve of Electrical power supply to heating element 12 as a function of time. For this curve, no unit of electrical power is determined. However, points on this curve located opposite 0 on the left ordinate axis indicate that the resistor is not powered. Conversely, The points on this curve located opposite the 78 on the left y-axis indicate that the resistor is supplied with an electrical power of approximately 2600W. The measured differences begin at time 0. In the first phase, which lasts from 0 to 4 seconds, the measured temperature of the liquid is 25°C, which is the ambient temperature of the liquid being heated. At time 4s, the user commands, by acting on the control medium 7, the activation of the device. (This instant is symbolized by the reference "ON") and sets a time command "Tpmin" of 21s, which corresponds to 21cl of heated liquid. During this 4s time, the heating element 12 is then powered with 2600W and the liquid temperature determined by the "CTN (T)" curve rises rapidly above 25°C. From time 4s to time 7s, that is, in 3s, the temperature of the liquid rose from 25 to 55°C. The first temperature limit TI being set at 55°C, the electronic control unit that receives the temperature information then commands the pump to start up at its nominal flow rate of lcl per second for a duration equal to the time command "Tpmin" selected by the user. The liquid then circulates in the transport circuit for 21s, that is, from time 7s to time 28s. It should be noted that the time "Tpmin" intervenes in the control process of the invention to define the start-up time based on the pump after the passage of the first limit TI. Despite the pump being put into operation, the liquid temperature continues to rise and reaches the second limit T2, set at 95°C, at time 10s. This temperature increase while the pump is running is linked to the fact that the ratio R of the heating power expressed in Watts divided by the fixed flow rate of liquid generated by the pump is greater than 2000. From the detection of the second limit T2, which is regulated at 95°C, the electronic control unit 5 cuts off the power supply for heating element 12. From time 10s, when this time cut occurs, the temperature continues to increase until it reaches a peak of 105°C at time lis. Beyond this time 13s, the liquid temperature decreases and reaches approximately 89°C, which is the third limit T3, at time 13s. This limit T3 is preferably calculated by subtracting a temperature delta value from the second limit T2. Thus, the third limit T3 is always slightly lower than the second limit T2, and in the case of the illustrated example, this temperature delta is 1°C. This delta can be between 1°C and 10°C. The temperature delta is chosen as low as possible because the smaller this delta, the smaller the variation in the water temperature at the outlet of the heating device will be. Ideally, the water temperature at the outlet of the device should tend towards a constant. Starting from T3, the control unit then feeds back power to the electrical resistance 12, as visible on the heating power curve P, which goes from 0 to 2600W in 13s. The liquid's temperature continues to decrease due to thermal inertia, then rises rapidly after having a minimum temperature of 62°C, tending towards a temperature close to 90°C. Then, the end of the heating cycle, according to the invention process, is interrupted at time 28s where the control unit simultaneously cuts off the power supply to the heating element and the pump. Alternatively, the heating cycle could have to be prolonged without stopping the pump, exactly continuing to measure the evolution of the liquid temperature and supplying power to the heating element when the temperature decreases below T3, and cutting off this power supply when the liquid temperature increases above T2. One possible option for the device control process could be to circulate the liquid in this heating device 1, at a minimum flow rate Dmin lower than the nominal flow rate D, before the liquid temperature T has reached the first temperature limit Tl. This feature allows dispensing a small amount of liquid that is not yet sufficiently hot (below Tl), provided the user gives the impression that the device is instantly available. In all cases, the liquid temperature will exceed the Tl limit within 3 seconds, according to the user's command. According to the invention options, the following are chosen: - the first temperature limit Tl between 50 and 70°C and, preferably, at 55°C; - the second temperature limit T2 between 80 and 100°C, preferably at 90°C; - the third temperature limit T3 is lower than T2 by a temperature delta value between 1 and 10°C, and preferably 1°C.

Claims

CLAIMS 1. Process for preparing a beverage by supplying hot water through a liquid transport circuit (2), comprising: a heating element (8) which has a heating resistance (12); a pump (14) arranged in series with the heating element (8) and adapted to ensure the circulation of liquid in the circuit (2), the process being such that, after activation by a user of a command means (7): - the liquid is heated by supplying the heating element with a predefined average electrical power, and the temperature of the heated liquid (T) is measured; - the liquid remains heated; and, - provided that the measured temperature (T) is higher than a first predetermined temperature limit (Tl), the liquid for the beverage is circulated in this heating element (8), with a determined constant nominal flow rate (D), characterized by the fact that this determined constant nominal flow rate (D) is less than 2 cl / second, the average electrical power of the heating resistance (12) being such that the ratio (R) of this power expressed in watts divided by the constant nominal flow rate expressed in centiliters per second is greater than 2000.

2. Process according to claim 1, characterized by the fact of this flow nominal constant determined be understood between 0.5 and 1.5 cl / second. Process, according with any of Claims 1 or 2, characterized by the fact that the ratio (R) between this predefined average electrical power and the determined constant nominal flow rate is predefined, at a constant and predefined value between 2000 and 4000.

4. A process, according to any one of claims 1, 2 or 3, characterized by the fact that the power supply to the heating element is cut off as soon as the measured temperature (T) is above a second limit (T2), while maintaining the circulation of the liquid, and the circulation of the fluid is cut off when the desired quantity of liquid has been supplied to the user.

5. Process, according to claim 4, characterized in that, after the power supply to the heating element (12) has been cut off, while maintaining the circulation of the liquid, the heating element (12) is re-supplied, provided that the measured temperature (T) is below a third temperature limit (T3) lower than the second (T2) and higher than the first (T1), and the cycle of cutting off / re-supplying the heating element is restarted, as the case may be, until the desired quantity of liquid has been supplied to the user.

6. Process, according to any one of claims 1, 2, 3, 4 or 5, characterized in that, before the liquid temperature (T) has reached the first temperature limit (Tl), the liquid is circulated to the beverage in this heating device (1), at a minimum low flow rate (Dmin) lower than the nominal flow rate (D).

7. Process, according to any of the claims 1, 2, 3, 4, 5 or 6, characterized in that the first temperature limit (Tl) is between 50 and 70 °C and is preferably 55 °C.

8. Process, according to any one of claims 4, 5, 6 or 7, characterized in that the second temperature limit (T2) is between 80 and 100 °C and is preferably 90 °C.

9. Process according to any one of claims 7 or 8, combined with claims 5 and 6, characterized in that the third temperature limit T3 is lower than the second limit (T2) by a delta value between 1 and 10 °C and, preferably, by 1 °C.

10. Process according to any one of claims 1, 2, 3, 4, 5, 6, 7, 8 or 9, characterized in that the pump (14) and the heating element (8) are controlled independently of each other by an electronic control unit (5) equipped with an electrical power supply and a control means (7), the process being activated by a single initial command exercised by the user on the control means (7), and to Upon receiving this command, the electronic control unit generates the set of actions for the process.

11. Process, according to any of claims 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, characterized by the fact that the average electrical power of heating element (12) must be less than 3500 Watts.

12. Device (1) for preparing a beverage by supplying hot water, comprising: a liquid transport circuit (2); an electronic control unit (5) equipped with an electrical power supply and a means of controlling the device (7); the transport circuit (2) comprising: a liquid heating element (8), comprising a heating resistor (12), the heating element being arranged in series with a pump (14) adapted to ensure the circulation of liquid in the circuit (2) with a determined flow rate (D), the pump (14) and the heating element (8) being electrically powered and controlled independently of each other by the control unit (5); characterized by the fact that the pump and the heating element are such that the ratio (R) of the average electrical power (P) of the heating resistance (12), expressed in Watts, divided by the nominal liquid flow rate (D) that can be ensured by the pump (14) of the transport circuit (2) and expressed in centiliters per second, is greater than 2000.

13. Device (1), according to claim 12, characterized in that the heating element (8) and the pump are dimensioned in such a way that the ratio (R) is between 2000 and 4000.

14. Device (1), according to any one of claims 12 or 13, characterized in that the heating element comprises a main body (9), associated with a complementary element (10) that covers one face of the main body (9), to define a liquid circulation volume, this complementary element (10) having a screen-printed heating resistance (12). on its opposite face (13) to that in front of the main body (9).

15. Device (1), according to any one of claims 12, 13 or 14, characterized in that the heating element (12) is controlled wholly or not at all by the control unit (5).

16. Device (1), according to any one of claims 12, 13, 14 or 15, characterized in that it comprises a temperature sensor (C) connected to the control unit (5) and arranged to capture a temperature (T) on a circuit part located between the heating element (8) and a free end (4) of the liquid transport circuit (2).

17. Device (1), according to claim 16, characterized in that the temperature sensor (C) is a thermistor with a Negative Temperature Coefficient (CTN).

18. Device (1), according to any one of claims 12, 13, 14, 15 or 16, characterized in that the transport circuit (2) comprises a liquid reservoir (15) connected in series with the pump. (14) through one end of the circuit (3) and supplying the circuit (2) with liquid to be heated.

19. Device (1), according to claim 18, characterized in that this reservoir (15) is removable and equipped with a shut-off valve (16) that automatically opens a fluid passage (17) from the reservoir. (15) towards the pump (14), when the reservoir (15) is connected to the feed end (3) and automatically blocking this passage (17), when the reservoir (15) for disconnected from the power supply end (3).

20. Device (1), according to any one of claims 12, 13, 14, 15, 16, 17, 18 or 19, characterized in that the main body has a thermal inertia lower than that of aluminum.

21. Device (1), according to any one of claims 14, 15, 16, 17, 18, 19 or 20, characterized in that the complementary element (10) is made of metallic material that has a transverse thermal conductivity coefficient (Cth) greater than 40.

22. Device (1), according to any one of claims 12, 13, 14, 15, 16, 17, 18, 19, 20 or 21 combined with claim 14, characterized in that the main body (9) has a groove that allows defining with the complementary element (10) a channel (4) for the circulation of the liquid.

23. Device (1), according to claim 22, characterized in that the main body (1) is flattened and the groove is spiral-shaped.

24. Device (1), according to any one of claims 12, 13, 14, 15, 16, 17, 18, 19, 20 or 21, combined with claim 14, characterized in that the main body (9) is cylindrical and receives on its outer face the complementary element (10) in the form of a sleeve.

25. Device according to any one of claims 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24, characterized in that the average electrical power of the heating element (12) is less than 3500 Watts.