CN107796040A - Solar water heating system heat storage water tank is layered controlling Method for inflow - Google Patents

Abstract

The invention discloses a kind of solar water heating system heat storage water tank to be layered controlling Method for inflow, according to the temperature difference between heat collector water outlet and heat storage water tank stratified water, the layered position for entering heat storage water tank to heat collector water outlet automatically controls, and has the function that to improve heat storage water tank thermal stratification effect.Solar water heating system heat storage water tank layering controlling Method for inflow proposed by the invention, it can effectively improve the stable layered effect of heat storage water tank, the delivery quality and reliability of domestic hot-water is improved, the efficiency of energy utilization of system is improved, suitable for big-and-middle-sized solar water heating system.

Description

Stratified water inlet control method for hot water storage tanks in solar water heating system

technical field

The invention relates to the control field of a solar water heating system, in particular to a method for controlling layered water intake of a hot water storage tank of a solar water heating system.

Background technique

Solar water heating system is one of the most mature and effective ways to utilize solar energy. As an important heat storage device of the solar water heating system, the hot water storage tank can effectively solve the intermittency and unreliability of solar energy itself and improve the utilization rate of solar energy. Because the density of water is inversely proportional to the temperature, the low-temperature hot water in the water tank has a high density and gathers at the bottom of the water tank, while the high-temperature hot water has a low density and floats to the top of the water tank, thus realizing the vertical stratification of water of different temperatures in the water tank Phenomenon.

When the solar system is running, the hot water generated by the collector will enter the hot water storage tank at a certain flow rate. Since there is a certain temperature difference between the incoming hot water and the hot water at the inlet when they mix, not only will there be obvious disturbances at the water inlet, but also the convection phenomenon caused by the temperature difference will also make the temperature stratification disorder, thereby increasing the thermocline layer. The thickness of the water tank seriously affects the temperature stratification phenomenon in the water tank. In addition, because the temperature of the top layer of the hot water storage tank is at a low level, it will affect the quality and reliability of the hot water supply of the system, thereby affecting the overall performance of the hot water system.

The stratification effect of the water tank can directly affect the operation effect of the entire solar water heating system. A water tank with good heat storage performance can not only meet the needs of the user's heat load, reduce the amount of auxiliary heating, but also reduce the inlet water temperature of the collector and improve Solar energy efficiency.

Contents of the invention

The technical problem to be solved by the present invention is to provide a layered water inlet control method for a hot water storage tank of a solar water heating system in view of the deficiencies in the prior art.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a method for controlling stratified water inflow to a hot water storage tank of a solar water heating system, comprising the following steps:

1) Divide the hot water storage tank into n+1 temperature layers, in which the water inlet is located on the upper n layers of the hot water storage tank, which are respectively recorded as 1, 2..., i,...n layers, and the water outlet is set at the heat storage The bottom layer of the water tank is recorded as layer 0; temperature sensors are installed in the water body of each temperature layer to continuously monitor the water temperature of each temperature layer, which are respectively recorded as T0, T1, T2..., Ti,...Tn; at the same time, the solar collectors are monitored The outlet water temperature is denoted as Tc; the 1st, 2nd..., i,...n layers of the water inlet are respectively equipped with valves V1..., Vi,...Vn; the 0th layer of the water outlet is equipped with a valve V0;

2) When the difference Tc-T0 between the measured water temperature Tc of the solar collector and the bottom temperature T0 of the hot water storage tank is greater than the minimum opening temperature difference set value SD1, Tc and the temperature layer 1 to n in the hot water storage tank The water temperatures T1 to Tn are compared respectively, and the temperature layer with the smallest absolute difference is judged, and the temperature layer with the smallest absolute difference is recorded as m;

a) If the current inlet valve switch signal B≠m, and when the continuous operation duration C of the same state is greater than the set value SD3:

①If B=-1, that is, when all the valves at the water inlet and outlet are closed, open the valve V0 of the water outlet pipeline and the valve Vm of the water inlet pipeline at the bottom of the hot water storage tank, and turn on the collector circulating water pump, so that B=m;

② If B≠-1, close the valve VB of the water inlet pipeline of the hot water storage tank, and open the valve Vm;

b) If the current inlet valve switch signal B≠m, and when the continuous operation time of the same state is C≤SD3, maintain the current switch state of all valves unchanged;

c) If the current inlet valve switch signal B=m, keep the current switch status of all valves unchanged;

3) When the difference Tc-T0 between the measured water outlet temperature Tc of the collector and the bottom temperature T0 of the hot water storage tank is less than the set value SD2 of the maximum closing temperature difference:

a) If the current valve switch signal B≠-1, then close all the valves V0 to Vn, turn off the collector circulating water pump, and make B=-1;

b) If the current valve switch signal B=-1, then continue to keep all the valves V0 to Vn closed, and continue to keep the heat collector circulating water pump closed;

4) When the difference Tc-T0 between the measured water outlet temperature Tc of the collector and the bottom temperature T0 of the hot water storage tank is between the maximum closing temperature difference SD2 and the minimum opening temperature difference SD1, the on-off state of the valve of the heat collecting system is maintained. Change, and according to the above steps 1) and 2) to judge and adjust the switching status of the valve and circulating pump.

In the present invention, the volume of the hot water storage tank is ≥600L; the hot water storage tank is cylindrical, and the ratio of the height to diameter of the cylindrical shape ranges from 3.0 to 4.0; the temperature layer of the hot water storage tank The range of number N is 4~10 layers, and the height range of each temperature layer is 0.1~0.4m; the range of temperature difference SD1 is 4.0~10.0°C, the range of SD2 is 1.0~5.0°C, and SD1 is greater than SD2, The difference between SD1 and SD2 is greater than 1.0°C; the set value SD3 ranges from 30 to 120 seconds; the temperature measurement range of the temperature sensor is -20°C to 100°C, and the temperature measurement accuracy is ±0.1°C.

Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention judges the temperature layer of the water tank with the smallest water temperature difference from the collector outlet by comparing the water temperature of each layer of the hot water storage tank with the water temperature at the outlet of the heat collector, and opens the corresponding The automatic control valve at the water inlet of this layer of the hot water storage tank closes the previous valve, and the outlet water of the collector is introduced into the temperature stratified water body of the hot water storage tank with the smallest temperature difference, thereby reducing the temperature stratification of the water tank Improve the system efficiency and the reliability of hot water supply; maintain the hot water in the hot water storage tank in a relatively stable stratified state, reduce the efficiency reduction caused by the mixing of cold and hot water; good temperature stratification It can reduce the time for the temperature of the top layer of the water tank to reach the predetermined requirement, and improve the quality and reliability of the system water supply; it is widely applicable to various solar hot water layered hot water storage tanks, and can even be derived into non-solar heat source hot water storage tanks. For example, a heat storage tank with a heat pump as a heat source.

Description of drawings

Fig. 1 is the schematic diagram of the layered water inlet control method of the hot water storage tank of the solar water heating system in the present invention, wherein:

1-1——Solar collector 1-2——Control module

1-3——solar circulation pump 1-4——automatic control valve

1-5——Hot water storage tank 1-6——Temperature sensor (collector outlet)

1-7——Temperature sensor (each layer of the hot water storage tank) V0——Control valve of the water outlet pipeline at the bottom of the water tank

V1..., Vi,...Vn——Valves of the water inlet pipeline for each stratified temperature of the water tank

Fig. 2 is a flow chart of the control method of the present invention.

Detailed ways

Figure 1 is the technical schematic diagram of the water from the collector entering the water tank in layers according to temperature. The control valve is connected with the control module 1-2. In addition, a temperature sensor 1-6 is installed at the outlet of the heat storage tank, and a temperature sensor 1-7 is installed in each layer of the hot water storage tank, and all temperature sensors are connected to the control module 1-2 through signal lines.

With reference to Fig. 2, control method flowchart of the present invention, concrete operation is as follows:

(1) In the control module 1-2, the inlet and outlet switch signal B of the hot water storage tank is preset to be "-1" (that is, all the inlet and outlet valves are closed, and the heat collection circulation pump is closed), and the heat collection circulation water pump is continuously turned on for a length of C If it is "0", read the minimum open temperature difference set value SD1, read the maximum close temperature difference set value SD2, and read the minimum operating state transition time set value SD3. (step S1)

(2) The temperature sensor 1-6 at the outlet of the heat collector continuously transmits the temperature signal Tc to the control module 1-2, and the temperature sensors 1-7 of each layer of the hot water storage tank continuously report the water temperature Ti of each layer (each layer is T0, T1, T2...Tn) are sent to the control module 1-2. (step S2)

(3) Calculate the difference between Tc and T0, denoted as TJ. (step S3)

(4) Determine the size relationship between TJ and SD1. (step S4)

(5) If TJ is smaller than SD1, it is judged whether B is equal to "-1" (step L1).

If B is not equal to "-1", then judge the size relationship between TJ and SD2 (step L2), if TJ is less than SD2, then close the collector side circulation pump 1-3 and all control valves V0 to Vn (step L3), return In step S2, if TJ is greater than SD2, it is equal to "-1", and directly returns to step S2.

(6) If TJ is greater than or equal to SD1, calculate the absolute difference between the temperature Ti (T1 to Tn) of each layer corresponding to the water inlet on the collector side of the hot water storage tank and the water temperature Tc at the outlet of the collector, and denote it as Tdi. (step S5)

(7) Compare and obtain the minimum value of Tdi, and record the corresponding number of layers of the hot water storage tank as m. (step S6)

(8) Judge whether B is equal to m. (step S7)

(9) If B is equal to m, directly return to step S2.

(10) If B is not equal to m, judge the size of C and SD3. (step S8)

(11) If C is greater than SD3, close the control valve VB and proceed to step S10. (step S9)

(12) Open the control valve Vm, set B equal to m, start timing and record it as C. (step S10)

(12) If C is less than or equal to SD3, then judge whether B is equal to "-1". (step L4)

If B is equal to "-1", then turn on the heat collecting circulating water pump 1-3 and control valve V0 (step L4), and then execute step S10; if B is not equal to "-1", then directly return to step S2.

(13) Determine whether the system receives a power-on signal. (step S11)

(14) If a shutdown signal is received, the circulation pump and all control valves are closed to end the cycle. (step S12)

(15) If the shutdown signal is not received, then directly return to step S2.

Claims (7)

1. a kind of solar water heating system heat storage water tank is layered controlling Method for inflow, it is characterised in that comprises the following steps：

1) heat storage water tank being divided into n+1 temperature layer, wherein water inlet end is located at the n-layer on heat storage water tank top, be designated as 1 respectively, 2 ..., i ... n-layer, water side are arranged at the heat storage water tank bottom, are denoted as 0 layer；Reload temperature senses in each temperature layer water body Device, the water temperature of each temperature layer of continuous monitoring, be designated as T0, T1, T2 respectively ..., Ti ... Tn；Monitor going out for solar thermal collector simultaneously Coolant-temperature gage, it is denoted as Tc；Water inlet end the 1st, 2 ..., i ... n-layer be respectively equipped with valve V1 ..., Vi ... Vn；Water side is the 0th layer and set There is valve V0；

2) when the solar thermal collector leaving water temperature Tc measured and heat storage water tank near-bottom temperature T0 difference Tc-T0 open more than minimum When opening temperature difference setting value SD1, by Tc with heat storage water tank 1 to the water temperature T 1 of n temperature layers to Tn respectively compared with, and judge exhausted To the temperature layer that difference is minimum, the minimum temperature layer of the absolute difference is designated as m；

If a) current entry valve switch signal B ≠ m, and when same state continuous running time C is more than setting value SD3：

1. when if B=-1, i.e. water inlet end, all valves in water side are turned off, then heat storage water tank bottom outlet pipeline valve is opened Door V0 and inlet pipeline valve Vm, opens thermal-arrest water circulating pump, makes B=m；

2. if B ≠ -1, closes heat storage water tank inlet pipeline valve VB, valve Vm is opened；

If b) current entry valve switch signal B ≠ m, and as same state continuous running time C≤SD3, would remain all The current switch states of valve are constant；

If c) during current entry valve switch signal B=m, maintain the valvular current switch states of institute constant；

3) when the heat collector leaving water temperature Tc measured and heat storage water tank near-bottom temperature T0 difference Tc-T0 is less than the maximum closing temperature difference During setting value SD2：

If a) during current valve switching signal B ≠ -1, closing all valve V0 to Vn, thermal-arrest water circulating pump is closed, and make B =-1；

If b) during current valve switching signal B=-1, continuing to keep all valve V0 to Vn closed mode constant, continue Keep the closing of thermal-arrest water circulating pump；

4) when the heat collector leaving water temperature Tc measured and heat storage water tank near-bottom temperature T0 difference Tc-T0 closes the temperature difference between maximum When between SD2 and minimum unlatching temperature difference SD1, maintain the on off state of collecting system valve constant, and according to above-mentioned steps 1) and 2) on off state of adjustment valve and circulating pump is judged.

2. solar water heating system heat storage water tank according to claim 1 is layered controlling Method for inflow, it is characterised in that institute State heat storage water tank volume >=600L.

3. solar water heating system heat storage water tank according to claim 1 is layered controlling Method for inflow, it is characterised in that institute Heat storage water tank is stated as cylinder, the ratio range of the cylindrical height and diameter is 3.0~4.0.

4. solar water heating system heat storage water tank according to claim 3 is layered controlling Method for inflow, it is characterised in that institute The scope for stating the temperature number of plies N of heat storage water tank is 4~10 layers, and the altitude range of each temperature layer is 0.1~0.4m.

5. solar water heating system heat storage water tank according to claim 1 is layered controlling Method for inflow, it is characterised in that temperature Poor setting value SD1 scope is 4.0~10.0 DEG C, and SD2 scope is 1.0~5.0 DEG C, and SD1 is more than SD2, SD1 and SD2 Difference is more than 1.0 DEG C.

6. solar water heating system heat storage water tank according to claim 1 is layered controlling Method for inflow, it is characterised in that sets Definite value SD3 scope is 30~120 seconds.

7. the solar water heating system heat storage water tank layering controlling Method for inflow according to one of claim 1~6, its feature It is, the temperature-measuring range of the temperature sensor is -20 DEG C~100 DEG C, and temperature measurement accuracy is ± 0.1 DEG C.