CN111536689A

CN111536689A - Water heater with periodically-changed heating quantity

Info

Publication number: CN111536689A
Application number: CN201910595888.0A
Authority: CN
Inventors: 吴芷红; 麻晓飞; 陈燕慧; 高永强; 沈保山; 刘治彩; 张爱云; 王逸隆
Original assignee: Shandong Jiaotong University
Current assignee: Shandong Jiaotong University
Priority date: 2019-07-03
Filing date: 2019-07-03
Publication date: 2020-08-14
Anticipated expiration: 2039-07-03
Also published as: CN112923563A; CN112902453A; CN112923562B; CN112902453B; CN112923563B; CN111536689B; CN112923562A

Abstract

The invention provides a water heater, which comprises an electric heating device; a first electric heater and a second electric heater are respectively arranged in the first channel box and the second channel box; filling phase-change fluid in the first channel and/or the second channel; the first electric heater and the second electric heater are respectively arranged in a plurality of numbers, each electric heater is independently controlled, and the number of the first electric heater and the second electric heater which are started is periodically changed along with the change of time. The water heater is provided with the two parts of electric heaters, and the periodic frequent vibration of the elastic coil pipe can be realized by starting the two parts of the electric heaters in a number-changing manner in a period, so that good descaling and heating effects are realized.

Description

Water heater with periodically-changed heating quantity

Technical Field

The invention relates to hot water generating equipment, in particular to an intermittent vibration descaling water heater.

Background

The water heater is an essential household appliance in the family life at present. At present, an electric water heater is generally adopted and is used for heating. In applicant's prior application, a new coil type electric heating coil, such as CN106123306A, was developed and studied to vibrate the elastic tube bundle due to the expansion of the fluid therein caused by heating, thereby achieving heating and descaling effects.

However, in applications where it is found that continuous heating of the electric heater results in fluid stability of the internal electric heating means, i.e. the fluid is not flowing or is flowing very little, or the flow is stable, the vibration performance of the coil is greatly reduced, and thus the efficiency of the coil for descaling and heating is affected.

In a previous application (e.g., application No. 2019101874848), see fig. 10 and 10, of the university of Qingdao technology, intermittent heating was used to vibrate the coil, but the intermittent heating would result in failure to heat for a period of time, resulting in a decrease in heating power. Therefore, the invention is improved, adopts a more reasonable heating mode and improves the heating efficiency.

Disclosure of Invention

The invention provides an electric water heater with a novel heating device layout aiming at the defects of the water heater in the prior art. This water heater can improve heating efficiency to realize fine scale removal and heating effect.

In order to achieve the purpose, the invention adopts the following technical scheme:

a water heater comprises an electric heating device and a water tank, wherein the electric heating device is arranged in the water tank, the water tank comprises a water inlet pipe and a hot water outlet, the electric heating device comprises a first pipe box, a second pipe box and a coil pipe, the coil pipe is communicated with the first pipe box and the second pipe box to form closed circulation of heating fluid, and the electric heater is arranged in the first pipe box; the number of the coil pipes is one or more, each coil pipe comprises a plurality of arc-shaped pipe bundles, the central lines of the arc-shaped pipe bundles are arcs taking the first pipe box as a concentric circle, and the end parts of the adjacent pipe bundles are communicated, so that the end parts of the pipe bundles form free ends of the pipe bundles; a first electric heater and a second electric heater are respectively arranged in the first channel box and the second channel box; filling phase-change fluid in the first channel and/or the second channel; the first electric heater and the second electric heater are respectively arranged in a plurality of numbers, each electric heater is independently controlled, and the number of the first electric heater and the second electric heater which are started is periodically changed along with the change of time.

Preferably, the first electric heater and the second electric heater are respectively set to be n, one period is T, and then in a half period of 0-T/2, when T =0, all n of the first electric heater are turned off, and all n of the second electric heater are turned on;

then every T/2n time, the first electric heater starts one electric heater until the T/2 time heater is completely started, and simultaneously the second electric heater stops one electric heater until the T/2 time heater is completely closed;

and in the half period of T/2-T, every T/2n, the second electric heater starts one electric heater until the second electric heater is completely started in the period T, and simultaneously the first electric heater stops one electric heater until the first electric heater is completely stopped in the period T.

The invention has the following advantages:

1. the water heater is provided with the two parts of electric heaters, and the two parts of electric heaters are started by changing the number of the two parts of electric heaters in a period, so that fluid can be frequently evaporated and expanded in the elastic tube bundle, and the stability of single heating is damaged because the expansion and the flowing direction of steam are continuously and periodically changed, and the vibration of the elastic tube bundle is continuously driven, so that the heating efficiency and the descaling operation can be further realized.

2. The invention designs a layout of an electric heating device with a novel structure in a water tank, which can further improve the heating efficiency.

3. The invention increases the heating power of the coil pipe periodically and continuously and reduces the heating power, so that the heated fluid can generate the volume which is continuously in a changing state after being heated, and the free end of the coil pipe is induced to generate vibration, thereby strengthening heat transfer.

4. The invention optimizes the optimal relationship of the parameters of the coil pipe through a large amount of experiments and numerical simulation, thereby realizing the optimal heating efficiency.

Description of the drawings:

fig. 1 is a top view of an electric heating apparatus of the present invention.

Fig. 2 is a front view of the electric heating apparatus.

Fig. 3 is a coordinate diagram of intermittent heating of the electric heating device.

Fig. 4 is a graph of the coordinates of the periodic increase and decrease in heating power of the electric heating device.

Fig. 5 is a schematic coordinate diagram of another embodiment of periodically increasing and decreasing heating power of an electric heating device.

Fig. 6 is a coordinate diagram of the linear change of the heating power of the electric heating device.

Fig. 7 is a schematic layout diagram of an electric heating device arranged in a circular water tank.

Fig. 8 is a schematic view of the coil configuration.

Fig. 9 is a schematic view of the structure of the water tank.

Fig. 10 is a background art drawing.

In the figure: 1. coil pipe, 2, first pipe box, 3, free end, 4, free end, 5, inlet tube, 6, hot water outlet, 7, free end, 8, second pipe box, 9, connecting point, 10, electric heating device, 11, water tank, 12 pipe bundles, 13 electric heater.

Detailed Description

A water heater comprises an electric heating device 10 and a water tank 11, wherein the electric heating device 10 is arranged in the water tank 11, and the water tank 11 comprises a water inlet pipe 5 and a hot water outlet 6.

Preferably, the water tank is of cylindrical configuration.

Fig. 1 shows a top view of an electric heating apparatus 10, as shown in fig. 1, the electric heating apparatus 10 includes a first pipe box 2, a second pipe box 8 and a coil 1, the coil 1 is communicated with the first pipe box 2 and the second pipe box 8, a fluid circulates in the first pipe box 2, the second pipe box 8 and the coil 1 in a closed manner,

electric heaters

131, 132 are disposed in the electric heating apparatus 10, and the electric heater 13 is used for heating the fluid in the electric heating apparatus 10 and then heating water in a water tank by the heated fluid.

As shown in fig. 1-2, a first electric heater 131 and a second electric heater 132 are provided in the first and

second header tanks

2 and 8, respectively; the first channel box 2 and/or the second channel box 8 are filled with phase-change fluid; the number of the coil pipes 1 is one or more, each coil pipe 1 comprises a plurality of circular arc-shaped pipe bundles 12, the central lines of the circular arc-shaped pipe bundles 12 are circular arcs taking the first pipe box 2 as a concentric circle, the end parts of the adjacent pipe bundles 12 are communicated, and fluid forms serial flow between the first pipe box 2 and the second pipe box 8, so that the end parts of the pipe bundles form free ends 3 and 4 of the pipe bundles; the fluid is phase-change fluid, vapor-liquid phase-change liquid, the first electric heater 131 and the second electric heater 132 are in data connection with a controller, and the controller controls the first electric heater 131 and the second electric heater 132 to heat periodically along with the change of time.

Preferably, the first and

second headers

2 and 8 are provided along a height direction.

It has been found in research and practice that continuous power-stable heating of the electric heater results in a stable fluid formation of the internal electric heating means, i.e. the fluid is not flowing or has little fluidity, or the flow is stable, resulting in a greatly reduced vibrational performance of the coil 1, thereby affecting the efficiency of descaling and heating of the coil 1. There is therefore a need for an improvement to the electrical heating coil described above as follows.

Preferably, the

electric heaters

131 and 132 are alternately heated periodically with time.

As shown in fig. 3, during one period time T, the heating power of the first electric heater is P1, the heating power of the second electric heater is P2, and the change rule of P1 and P2 is as follows:

in a half period of 0-T/2, P1 ═ n, P2=0, where n is a constant value in watts (W), i.e., the first electric heater heating power is kept constant and the second electric heater does not heat;

and in the half period of T/2-T, P1=0 and P2= n. I.e. the first electric heater does not heat up, the heating power of the second electric heater is kept constant.

T is 50-80 minutes, where 2000W < n < 2500W.

Alternatively, in one period time T, the heating power of the first electric heater is P1, the heating power of the second electric heater is P2, and the change rule of P1 and P2 is as follows:

in a half period of 0-T/2, P2 ═ n, P1=0, where n is a constant value in watts (W), i.e., the first electric heater heating power is kept constant and the second electric heater does not heat;

half a period of T/2-T, P2=0, P1= n; i.e. the first electric heater does not heat up, the heating power of the second electric heater is kept constant.

Through the heating with the time variability, the fluid can be frequently evaporated and expanded in the elastic tube bundle, and the stability of single heating is damaged due to the continuous periodic change of the expansion and the flowing direction of the steam, so that the vibration of the elastic tube bundle is continuously driven, and the heating efficiency and the descaling operation can be further realized.

Compared with the prior application, the heating mode ensures that the electric heating device heats in the whole period, and the elastic tube bundle can vibrate frequently, so that the heating efficiency and the descaling operation can be further realized.

Preferably, the first electric heater 131 and the second electric heater 132 are respectively provided as a plurality of electric heaters, each of which is independently controlled, and the number of the electric heaters activated is periodically changed with time.

Preferably, the first electric heater 131 and the second electric heater 132 are respectively provided with n electric heaters, and if T is a period, n of the first electric heaters 131 are all turned off and n of the second electric heaters 132 are all turned on within a half period of 0-T/2, and T = 0;

then, the first electric heater 131 starts one electric heater every T/2n until the heaters are all started at T/2, and the second electric heater 132 turns off one electric heater until the heaters are all turned off at T/2.

In the half period of T/2-T, every T/2n, the second electric heater 132 starts one electric heater until the second heater is completely started in the period T, and simultaneously the first electric heater 131 turns off one electric heater until the first heater is completely turned off in the period T.

Preferably, the heating power of each electric heater is the same. The relationship diagram is shown in fig. 4.

Alternatively, if the period is T, then in a half period of 0-T/2, when T =0, all n of the second electric heaters 132 are turned off, and all n of the first electric heaters 131 are turned on;

then, every T/2n time, the second electric heater 132 starts one electric heater until the heaters are all started at the T/2 time, and simultaneously, the first electric heater 131 turns off one electric heater until the first heater is all turned off at the T/2 time.

In the half period of T/2-T, every T/2n, the first electric heater 131 starts one electric heater until the second heater is completely started in the period T, and the second electric heater 132 turns off one electric heater until the first heater is completely turned off in the period T.

Preferably, the

electric heaters

131 and 132 are provided in a plurality of stages along the height direction, each stage is independently controlled, and as time varies, all the stages of the first electric heater 131 are all turned off and all the stages of the second electric heater 132 are all turned on at T =0 in a half cycle of 0-T/2;

then the first electric heaters 131 are sequentially started from the lower end in the height direction until all the segments are started, and simultaneously the second electric heaters 132 are sequentially stopped from the upper end in the height direction until all the segments are stopped;

in a half period of T/2-T, the first electric heater 131 is sequentially turned off from the upper end, the second electric heater 132 is sequentially turned on from the lower end, and until the period is completed, all the segments of the first electric heater 131 are all turned off, and all the segments of the second electric heater 132 are all turned on.

That is, if the first electric heater 131 and the second electric heater 132 are n segments, all the segments of the first electric heater 131 are turned off and all the segments of the second electric heater 132 are turned on when T =0 in one period T;

then every T/2n time, starting one section from the lower end of the first electric heater 131 until all sections are started at the T/2 time, and simultaneously starting one section from the upper end of the second electric heater 132 until all sections are closed at the T/2 time;

then every T/2n time, the first electric heater is started from the upper end, and is closed for one section every T/2n time until all sections of the first electric heater are closed at T time, and simultaneously, the second electric heater is started from the lower end, and is opened for one section every T/2n time until all sections of the second electric heater are opened at T time.

Alternatively, in a half cycle of 0-T/2, when T =0, all segments of the first electric heater 131 are all turned on, and all segments of the second electric heater 132 are all turned off; then the first electric heaters 131 are sequentially turned off from the upper end in the height direction until all the segments are turned off, and simultaneously the second electric heaters 132 are sequentially turned on from the lower end in the height direction until all the segments are turned on;

in a half period of T/2-T, the second electric heaters 132 are sequentially turned off from the upper end, the first electric heaters 131 are sequentially turned on from the lower end, until the period is finished, all the segments of the second electric heaters 132 are all turned off, and all the segments of the first second electric heaters 131 are all turned on.

That is, if the first electric heater 131 and the second electric heater 132 are n segments, all the segments of the second electric heater 132 are turned off and all the segments of the first electric heater 131 are turned on when T =0 in one period T;

then every T/2n time, the second electric heater 132 starts to start one section from the lower end until all sections are started at T/2 time, and simultaneously the first electric heater 131 starts to stop one section from the upper end until all sections are stopped at T/2 time;

then every T/2n time, the second electric heater is started from the upper end, and is closed for one section every T/2n time until all sections of the second electric heater are closed at T time, and simultaneously, the first electric heater is started from the lower end, and is opened for one section every T/2n time until all sections of the first electric heater are opened at T time.

Preferably, the heating power is the same for each section. The relationship diagram is shown in fig. 4.

The electric heater is started from the lower part upwards gradually, so that the fluid at the lower part is fully heated, a good natural convection is formed, the flow of the fluid is further promoted, and the elastic vibration effect is increased. Through the change of the heating power with time variability, the fluid can be frequently evaporated, expanded and contracted in the elastic tube bundle, so that the vibration of the elastic tube bundle is continuously driven, and the heating efficiency and the descaling operation can be further realized.

Preferably, the first electric heater 131 is provided in plurality, each electric heater 131 has different power, and may be combined with one or more other electric heaters to form different heating power, and the second electric heater 132 is provided in plurality, and each electric heater 132 has different power.

In the period T, T =0, all of the plurality of first electric heaters 131 are turned off, all of the plurality of second electric heaters 132 are turned on,

as an option, in a half period of 0-T/2, according to a time sequence, starting a single first electric heater, independently starting the single first electric heater according to a sequence that heating power is sequentially increased, then starting two first electric heaters, independently starting the two first electric heaters according to a sequence that the heating power is sequentially increased, then gradually increasing the starting number of the first electric heaters, and if the number is n, independently starting the n first electric heaters according to a sequence that the heating power is sequentially increased; until all the first electric heaters are started, ensuring that the heating power of the first electric heaters is increased in sequence; simultaneously, the single second electric heater is closed, the single second electric heater is independently closed according to the sequence that the heating power is sequentially increased, then the two second electric heaters are closed, the two second electric heaters are independently closed according to the sequence that the heating power is sequentially increased, then the number of the closed second electric heaters is gradually increased, and if the number is n, the n second electric heaters are independently closed according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the second electric heaters is reduced in sequence until all the second electric heaters are turned off finally.

In the next half period of T/2-T, firstly, closing a single first electric heater, independently closing the single first electric heater according to the sequence that the heating power is sequentially increased, then closing two first electric heaters, independently closing the two first electric heaters according to the sequence that the heating power is sequentially increased, then gradually increasing the number of the closed first electric heaters, and if the number is n, independently closing the n first electric heaters according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the first electric heaters is reduced in sequence until all the first electric heaters are turned off finally. Meanwhile, according to the time sequence, firstly, a single second electric heater is started, the single second electric heater is independently started according to the sequence that the heating power is sequentially increased, then two second electric heaters are started, the two second electric heaters are independently started according to the sequence that the heating power is sequentially increased, then the starting number of the second electric heaters is gradually increased, and if the number is n, the n second electric heaters are independently started according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the second electric heaters is increased in sequence until all the second electric heaters are started finally.

For example, the number of the first electric heaters is three, namely a first electric heater D1, a first electric heater D2 and a first electric heater D3, and the heating power is P1, P2 and P3, wherein P1< P2< P3, P1+ P2> P3; that is, the sum of D1 and D2 is larger than D3, D1, D2, D3, D1 plus D2, D1 plus D3, D2 plus D3, then D1+ D2+ D3 are sequentially started in time sequence in the first half period, and the closing sequence in the second half period is D1, D2, D3, D1 plus D2, D1 plus D3, D2 plus D3.

The number of the second electric heaters is three, namely a second electric heater M1, a second electric heater M2 and a second electric heater M3, and the heating power is P1, P2 and P3, wherein P1< P2< P3, P1+ P2> P3; that is, the sum of M1 and M2 is greater than M3, M1, M2, M3, M1 plus M2, M1 plus M3, M2 plus M3, then M1+ M2+ M3 are sequentially closed in time sequence in the first half period, and the opening sequence in the second half period is M1, M2, M3, M1 plus M2, M1 plus M3, M2 plus M3.

Alternatively, in the period T, T =0, all of the plurality of second electric heaters 132 are turned off, all of the plurality of first electric heaters 131 are turned on,

in a half period of 0-T/2, according to time sequence, firstly starting a single second electric heater, independently starting the single second electric heater according to the sequence that the heating power is sequentially increased, then starting two second electric heaters, independently starting the two second electric heaters according to the sequence that the heating power is sequentially increased, then gradually increasing the starting number of the second electric heaters, and if the number is n, independently starting the n second electric heaters according to the sequence that the heating power is sequentially increased; until all the second electric heaters are started, the heating power of the first electric heaters is ensured to be increased in sequence; simultaneously, the single first electric heater is closed, the single first electric heater is independently closed according to the sequence that the heating power is sequentially increased, then the two first electric heaters are closed, the two first electric heaters are independently closed according to the sequence that the heating power is sequentially increased, then the number of the closed first electric heaters is gradually increased, and if the number is n, the n first electric heaters are independently closed according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the second electric heaters is reduced in sequence until all the second electric heaters are turned off finally.

In the next half period of T/2-T, firstly, the single second electric heater is closed, the single second electric heater is independently closed according to the sequence that the heating power is sequentially increased, then the two second electric heaters are closed, the two second electric heaters are independently closed according to the sequence that the heating power is sequentially increased, then the number of the closed second electric heaters is gradually increased, and if the number is n, the n second electric heaters are independently closed according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the second electric heater is reduced in sequence until all the electric heaters are turned off finally. Meanwhile, according to the time sequence, firstly, a single first electric heater is started, the single first electric heater is independently started according to the sequence that the heating power is sequentially increased, then two first electric heaters are started, the two first electric heaters are independently started according to the sequence that the heating power is sequentially increased, then the starting number of the first electric heaters is gradually increased, and if the number is n, the n first electric heaters are independently started according to the sequence that the heating power is sequentially increased; and ensuring that the heating power of the first electric heaters is increased in sequence until all the first electric heaters are started finally.

For example, the number of the second electric heaters is three, namely a second electric heater D1, a second electric heater D2 and a second electric heater D3, and the heating powers are P1, P2 and P3, wherein P1< P2< P3, P1+ P2> P3; that is, the sum of D1 and D2 is larger than D3, D1, D2, D3, D1 plus D2, D1 plus D3, D2 plus D3, then D1+ D2+ D3 are sequentially started in time sequence in the first half period, and the closing sequence in the second half period is D1, D2, D3, D1 plus D2, D1 plus D3, D2 plus D3.

The number of the first electric heaters is three, namely a first electric heater M1, a first electric heater M2 and a first electric heater M3, and the heating power is P1, P2 and P3, wherein P1< P2< P3, P1+ P2> P3; that is, the sum of M1 and M2 is greater than M3, M1, M2, M3, M1 plus M2, M1 plus M3, M2 plus M3, then M1+ M2+ M3 are sequentially closed in time sequence in the first half period, and the opening sequence in the second half period is M1, M2, M3, M1 plus M2, M1 plus M3, M2 plus M3.

The heating power is gradually increased and decreased through the electric heater, the flowing of the fluid is further promoted, and the elastic vibration effect is increased. Through the change of the heating power with time variability, the fluid can be frequently evaporated, expanded and contracted in the elastic tube bundle, so that the vibration of the elastic tube bundle is continuously driven, and the heating efficiency and the descaling operation can be further realized.

Preferably, the heating power of the electric heating device is linearly increased in the first half period, and the heating power of the electric heating device is linearly decreased in the second half period, see fig. 6.

The linear variation of the heating power is achieved by a variation of the input current or voltage.

By arranging the plurality of electric heaters, the starting of the electric heaters with gradually increased quantity is realized, and the linear change is realized.

Preferably, the period is 50 to 300 minutes, preferably 50 to 80 minutes; the average heating power of the electric heating device is 2000-4000W.

Preferably, the pipe diameter of the first pipe box 2 is equal to that of the second pipe box 8. The pipe diameters of the first pipe box and the second pipe box are equal, so that the fluid can be ensured to be subjected to phase change in the first box body and keep the same transmission speed as the second pipe box.

Preferably, the connection position 9 of the coil pipe at the first header is lower than the connection position of the second header and the coil pipe. This ensures that steam can rapidly enter the second header upwards.

Preferably, the bottom parts of the first channel box and the second channel box are provided with return pipes, so that the fluid condensed in the first channel box and the second channel box can quickly flow.

Preferably, the first and second headers are arranged in a height direction, the coil pipe is provided in plural numbers in the height direction of the first header, and a pipe diameter of the coil pipe is gradually reduced from top to bottom.

Preferably, the pipe diameter of the coil pipe is gradually decreased and gradually increased along the direction from the top to the bottom of the first pipe box.

The pipe diameter range through the coil pipe increases, can guarantee that more steam passes through upper portion and gets into first, two boxes, guarantees that the distribution of steam is even in all coil pipes, further reinforces the heat transfer effect for the whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.

Preferably, the plurality of coils are arranged along the height direction of the first tube box, and the distance between the adjacent coils is increased from the top to the bottom.

Preferably, the distance between the coils increases along the height direction of the first header.

The interval range through the coil pipe increases, can guarantee that more steam passes through upper portion and gets into first, two boxes, guarantees that the distribution of steam is even in all coil pipes, further strengthens heat transfer effect for the whole vibration effect is even, and the heat transfer effect increases, further improves heat transfer effect and scale removal effect. Experiments show that better heat exchange effect and descaling effect can be achieved by adopting the structural design.

Preferably, as shown in fig. 7, the water tank is a water tank having a circular cross section, and a plurality of electric heating devices are disposed in the water tank.

Preferably, as shown in fig. 7, a plurality of electric heaters are disposed in the water tank, one of which is disposed at the center of the water tank to become a central electric heater, and the others are distributed around the center of the water tank to become peripheral electric heaters. Through such structural design, can be so that the interior fluid of water tank fully reaches the vibration purpose, improve the heat transfer effect.

Preferably, the heating power of the single peripheral electric heating means is smaller than the heating power of the central electric heating means. Through the design, the center reaches higher vibration frequency to form a central vibration source, so that the periphery is influenced, and better heat transfer enhancement and descaling effects are achieved.

Preferably, on the same horizontal heat exchange section, the fluid needs to achieve uniform vibration, and uneven heat exchange distribution is avoided. It is therefore necessary to distribute the amount of heating power among the different electric heating devices reasonably. Experiments show that the heating power ratio of the central electric heating device to the peripheral tube bundle electric heating device is related to two key factors, wherein one of the two key factors is the distance between the peripheral electric heating device and the center of the water tank (namely the distance between the circle center of the peripheral electric heating device and the circle center of the central electric heating device) and the diameter of the water tank. Therefore, the invention optimizes the optimal proportional distribution of the pulsating flow according to a large number of numerical simulations and experiments.

Preferably, the radius of the inner wall of the water tank is B, the center of the central electric heating device is arranged at the center of the circular cross section of the water tank, the distance from the center of the peripheral electric heating device to the center of the circular cross section of the water tank is S, the centers of adjacent peripheral electric heating devices are respectively connected with the center of the circular cross section, the included angle formed by the two connecting lines is a, the heating power of the peripheral electric heating device is W2, and the heating power of a single central electric heating device is W1, so that the following requirements are met:

W1/W2= a-B Ln (B/S); ln is a logarithmic function;

a, b are coefficients, where 1.855< a <1.865,0.600< b < 0.610;

1.25<B/S<2.1；

1.4<W1/W2<1.8。

wherein 35 ° < a <80 °.

Preferably, the number of the four-side distribution is 4-5.

Preferably, R is 1600-2400 mm, preferably 2000 mm; l is 1200-2000 mm, preferably 1700 mm; the diameter of the heat exchange tube is 12-20 mm, preferably 16 mm; the outermost diameter of the pulsating coil is 300-. The diameter of the riser is 100-116 mm, preferably 108 mm, the height of the riser is 1.8-2.2 m, preferably 2 m, and the spacing between adjacent pulse tubes is 65-100 mm. Preferably around 80 mm.

The total heating power is preferably 4000-10000W, more preferably 5500W.

Further preferably, a =0.18606 and b = 0.6041.

Preferably, the box body has a circular cross section, and is provided with a plurality of electric heating devices, wherein one electric heating device is arranged at the center of the circular cross section and the other electric heating devices are distributed around the center of the circular cross section.

The coils 1 are in one or more groups, each group of coils 1 comprises a plurality of circular arc-shaped tube bundles 12, the central lines of the circular arc-shaped tube bundles 12 are circular arcs of concentric circles, and the ends of the adjacent tube bundles 12 are communicated, so that the ends of the coils 1 form tube bundle free ends 3, 4, such as the free ends 3, 4 in fig. 2.

Preferably, the heating fluid is a vapor-liquid phase-change fluid.

Preferably, the first header 2, the second header 8, and the coil 1 are all of a circular tube structure.

Preferably, the tube bundle of the coil 1 is an elastic tube bundle.

The heat exchange coefficient can be further improved by arranging the tube bundle of the coil 1 with an elastic tube bundle.

Preferably, the concentric circles are circles centered on the center of the first header 2. I.e. the tube bundle 12 of the coil 1 is arranged around the centre line of the first tube box 2.

As shown in fig. 4, the tube bundle 12 is not a complete circle, but rather leaves a mouth, thereby forming the free end of the tube bundle. The angle of the arc of the mouth part is 65-85 degrees, namely the sum of included angles b and c in figure 5 is 65-85 degrees.

Preferably, the ends of the tube bundle on the same side are aligned in the same plane, with the extension of the ends (or the plane in which the ends lie) passing through the median line of the first tube box 2.

Further preferably, the electric heater 13 is an electric heating rod.

Preferably, the first end of the inner tube bundle of the coil 1 is connected to the first tube box 2, the second end is connected to one end of the adjacent outer tube bundle, one end of the outermost tube bundle of the coil 1 is connected to the second tube box 8, and the ends of the adjacent tube bundles are connected to form a serial structure.

The plane in which the first end is located forms an angle c of 40-50 degrees with the plane in which the centre lines of the first and

second headers

2, 8 are located.

The plane of the second end forms an angle b of 25-35 degrees with the plane of the centre lines of the first and

second headers

2, 8.

Through the design of the preferable included angle, the vibration of the free end is optimal, and therefore the heating efficiency is optimal.

As shown in fig. 8, there are 4 tube bundles of coil 1, with tube bundles A, B, C, D in communication. Of course, the number is not limited to four, and a plurality of the connecting structures are provided as required, and the specific connecting structure is the same as that in fig. 8.

The number of the coil pipes 1 is multiple, and the plurality of coil pipes 1 are respectively and independently connected with the first pipe box 2 and the second pipe box 8, that is, the plurality of coil pipes 1 are in a parallel structure.

Although the present invention has been described with reference to the preferred embodiments, it is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A water heater comprises an electric heating device and a water tank, wherein the electric heating device is arranged in the water tank, the water tank comprises a water inlet pipe and a hot water outlet, the electric heating device comprises a first pipe box, a second pipe box and a coil pipe, the coil pipe is communicated with the first pipe box and the second pipe box to form closed circulation of heating fluid, and the electric heater is arranged in the first pipe box; the number of the coil pipes is one or more, each coil pipe comprises a plurality of arc-shaped pipe bundles, the central lines of the arc-shaped pipe bundles are arcs taking the first pipe box as a concentric circle, and the end parts of the adjacent pipe bundles are communicated, so that the end parts of the pipe bundles form free ends of the pipe bundles; a first electric heater and a second electric heater are respectively arranged in the first channel box and the second channel box; filling phase-change fluid in the first channel and/or the second channel; the electric heating device is characterized in that the first electric heater and the second electric heater are respectively provided with a plurality of electric heaters, each electric heater is independently controlled, and the starting number of the first electric heater and the second electric heater is periodically changed along with the change of time.

2. The water heater as claimed in claim 1, wherein the first electric heater and the second electric heater are respectively set to be n, one period is T, and then within a half period of 0-T/2, when T =0, n of the first electric heaters are all turned off, and n of the second electric heaters are all turned on;

3. A water heater comprises an electric heating device and a water tank, wherein the electric heating device is arranged in the water tank, the water tank comprises a water inlet pipe and a hot water outlet, the electric heating device comprises a first pipe box, a second pipe box and a coil pipe, the coil pipe is communicated with the first pipe box and the second pipe box to form closed circulation of heating fluid, and the electric heater is arranged in the first pipe box; the number of the coil pipes is one or more, each coil pipe comprises a plurality of arc-shaped pipe bundles, the central lines of the arc-shaped pipe bundles are arcs taking the first pipe box as a concentric circle, and the end parts of the adjacent pipe bundles are communicated, so that the end parts of the pipe bundles form free ends of the pipe bundles; a first electric heater and a second electric heater are respectively arranged in the first channel box and the second channel box.