CN107796040B - Layered water inlet control method for heat storage water tank of solar water heating system - Google Patents

Layered water inlet control method for heat storage water tank of solar water heating system Download PDF

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CN107796040B
CN107796040B CN201710052042.3A CN201710052042A CN107796040B CN 107796040 B CN107796040 B CN 107796040B CN 201710052042 A CN201710052042 A CN 201710052042A CN 107796040 B CN107796040 B CN 107796040B
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water
temperature
layer
solar
difference
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CN107796040A (en
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周晋
徐峰
杨静波
张国强
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Hunan University
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Hunan University
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24DDOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00Domestic hot-water supply systems
    • F24D17/0015Domestic hot-water supply systems using solar energy
    • F24D17/0021Domestic hot-water supply systems using solar energy with accumulation of the heated water
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00Integration of renewable energy sources in buildings
    • Y02B10/20Solar thermal
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00Integration of renewable energy sources in buildings
    • Y02B10/70Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies

Abstract

The invention discloses a layered water inlet control method for a heat storage water tank of a solar water heating system, which automatically controls the layered position of the outlet water of a heat collector entering the heat storage water tank according to the temperature difference between the outlet water of the heat collector and the layered water body of the heat storage water tank, thereby achieving the effect of improving the temperature layering effect of the heat storage water tank. The layered water inlet control method for the heat storage water tank of the solar water heating system can effectively improve the stable layering effect of the heat storage water tank, improve the quality and reliability of domestic hot water supply, improve the energy utilization efficiency of the system, and is suitable for large and medium solar water heating systems.

Description

Layered water inlet control method for heat storage water tank of solar water heating system
Technical Field
The invention relates to the field of solar water heating system control, in particular to a layered water inlet control method for a heat storage water tank of a solar water heating system.
Background
The solar water heating system is one of the mature and effective solar energy utilization modes in the prior art. The heat storage water tank is used as an important heat storage device of the solar water heating system, so that the intermittent and unreliable solar energy can be effectively solved, and the utilization rate of the solar energy is improved. Because the density of water is inversely proportional to the temperature, the low-temperature hot water in the water tank has high density and gathers at the bottom of the water tank, and the high-temperature hot water has low density and floats to the top of the water tank, so that the vertical layering phenomenon of water with different temperatures in the water tank is realized.
When the solar system operates, hot water generated by the heat collector can enter the hot water storage tank at a certain flow rate. Because the hot water that gets into has certain difference in temperature with the hot water of entrance when mixing, not only can produce obvious disturbance at the water inlet, the convection current phenomenon that the difference in temperature arouses also can make the temperature layering take place disorderly moreover to increase the thickness on inclined temperature layer, the temperature layering phenomenon in the tight ghost sound water tank. In addition, the temperature of the top layer of the hot water storage tank is at a lower level, so that the quality and reliability of hot water supply of the hot water system are affected, and the overall performance of the hot water system is affected.
The water tank with good heat storage performance can not only meet the requirement of heat load of a user, reduce the auxiliary heating quantity, but also reduce the inlet water temperature of the heat collector and improve the utilization efficiency of solar energy.
Disclosure of Invention
The invention aims to solve the technical problem of providing a layered water inlet control method for a heat storage water tank of a solar water heating system aiming at the defects of the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a layered water inlet control method for a hot water storage tank of a solar water heating system comprises the following steps:
1) dividing the heat storage water tank into n +1 temperature layers, wherein the n layers with water inlet ends positioned at the upper part of the heat storage water tank are respectively marked as 1 layer, 2 … layer, i layer and … n layer, and the water outlet ends are arranged at the bottommost layer of the heat storage water tank and are marked as 0 layer; additionally arranging temperature sensors in the water bodies of the temperature layers, and continuously monitoring the water temperatures of the temperature layers, wherein the water temperatures are respectively marked as T0, T1, T2 …, Ti and … Tn; simultaneously monitoring the water outlet temperature of the solar thermal collector and recording as Tc; the 1 st, 2 nd 2 … th, i th and … n layers of the water inlet end are respectively provided with valves V1 …, Vi and … Vn; the water outlet end is a 0 th layer and is provided with a valve V0;
2) when the difference Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is larger than the minimum opening temperature difference set value SD1, respectively comparing Tc with the water temperatures T1-Tn of the temperature layers from 1 to n in the hot water storage tank, judging the temperature layer with the minimum absolute difference, and recording the temperature layer with the minimum absolute difference as m;
a) if the current opening state inlet valve number B is not equal to m, and when the continuous operation time length C in the same state is less than or equal to the operation state transition minimum time length set value SD 3:
①, if B is-1, namely all valves at the water inlet end and the water outlet end are closed, and the heat collection circulating water pump is also closed, opening a water outlet pipeline valve V0 and a water inlet pipeline valve Vm at the bottom layer of the heat storage water tank, opening the heat collection circulating water pump, making B m, starting timing and recording as C;
②, if B ≠ -1, keeping the current switch states of all valves unchanged;
b) if the inlet valve number B of the current opening state is not equal to m, and when the continuous operation time length C of the same state is longer than SD3, closing the valve VB, opening the valve Vm, making B equal to m, starting timing and recording as C;
c) if the number B of the inlet valve in the current opening state is m, maintaining the current opening and closing states of all the valves unchanged;
3) when the difference Tc-T0 between the measured outlet water temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is not more than the minimum opening temperature difference set value SD 1:
a) if the number B of the inlet valve in the current opening state is not equal to-1, judging whether the difference value Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the heat storage water tank is smaller than a maximum closing temperature difference set value SD2, if so, closing all the valves V0 to Vn, closing the heat collection circulating water pump, and enabling B to be equal to-1;
b) if the number B of the inlet valve in the current opening state is equal to-1, continuously keeping the closing states of all the valves V0 to Vn unchanged, and continuously keeping the heat collection circulating water pump closed;
4) when the difference Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is between the maximum closing temperature difference SD2 and the minimum opening temperature difference SD1, the switching state of a valve of the heat collecting system is kept unchanged, and the step 1) is returned; the temperature difference set value SD1 is in the range of 4.0-10.0 ℃, the range of SD2 is in the range of 1.0-5.0 ℃, SD1 is larger than SD2, and the difference between SD1 and SD2 is larger than 1.0 ℃.
In the invention, the volume of the heat storage water tank is more than or equal to 600L; the heat storage water tank is cylindrical, and the ratio of the height to the diameter of the cylinder ranges from 3.0 to 4.0; the number N of temperature layers of the heat storage water tank ranges from 4 to 10, and the height of each temperature layer ranges from 0.1 to 0.4 m; the range of the set value SD3 is 30-120 seconds; the temperature measuring range of the temperature sensor is-20-100 ℃, and the temperature measuring precision is +/-0.1 ℃.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the water temperature of each layer of the heat storage water tank is compared with the water temperature of the outlet of the heat collector, the water tank temperature layer with the minimum temperature difference with the outlet of the heat collector is judged, the automatic control valve at the position of the water inlet of the layer of the corresponding heat storage water tank is opened, and the previous valve is closed, so that the outlet of the heat collector is led into the heat storage water tank temperature layering water body with the minimum temperature difference with the heat storage water tank, thereby reducing the influence on the water tank temperature layering, and improving the system efficiency and the; the hot water in the heat storage water tank is maintained in a stable layered state, and the problem of efficiency reduction caused by mixing of cold water and hot water is reduced; the good temperature stratification can reduce the time for the top layer temperature of the water tank to reach the preset requirement, and improve the quality and reliability of water supply of the system; the heat pump type solar water heater is widely applicable to various solar hot water stratification heat storage water tanks, and can even be derived from heat storage water tanks without solar heat sources, such as the heat storage water tank with a heat pump as a heat source.
Drawings
Fig. 1 is a schematic diagram of a layered water inlet control method for a hot water storage tank of a solar water heating system, wherein:
1-solar heat collector 1-2-control module
1-3-solar circulating pump 1-4-automatic control valve
1-5-heat storage water tank 1-6-temperature sensor (heat collector outlet)
1-7-temperature sensor (each layer of heat storage water tank) V0-water outlet pipeline control valve at bottom layer of water tank
V1 …, Vi, … Vn-water tank layered temperature water inlet pipeline valve
Fig. 2 is a flow chart of a control method of the present invention.
Detailed Description
FIG. 1 is a technical schematic diagram of the layered water inlet of a heat collector according to temperature, wherein an automatic control valve of a heat collection side circulating pump and a water outlet of a heat storage water tank is connected with a control module 1-2, and an automatic control valve of a water inlet of the heat storage water tank is connected with the control module 1-2. In addition, temperature sensors 1-6 are installed at the outlet of the heat reservoir, temperature sensors 1-7 are installed in each layer of the heat storage water tank, and all the temperature sensors are connected with the control module 1-2 through signal lines.
Referring to fig. 2, the control method of the present invention is a flowchart, and specifically operates as follows:
(1) in the control module 1-2, the number B of an inlet valve of the heat storage water tank in an opening state is preset to be "-1" (namely, inlet and outlet valves are all closed, and a heat collection circulating pump is closed), the continuous opening time length C of the heat collection circulating water pump is set to be "0", a minimum opening temperature difference set value SD1 is read, a maximum closing temperature difference set value SD2 is read, and a minimum time length set value SD3 of the operation state transition is read. (step S1)
(2) The heat collector outlet temperature sensor 1-6 continuously transmits a temperature signal Tc to the control module 1-2, and each layered temperature sensor 1-7 of the heat storage water tank continuously transmits water temperature Ti of each layer (each layer is sequentially T0, T1 and T2 … … Tn) to the control module 1-2. (step S2)
(3) The difference between Tc and T0 is calculated and recorded as TJ. (step S3)
(4) And judging the size relationship between TJ and SD 1. (step S4)
(5) If TJ is less than SD1, it is determined whether B is equal to "-1" (step L1).
If B is not equal to "-1", the size relationship between TJ and SD2 is determined (step L2), and if TJ is smaller than SD2, the heat collecting side circulation pump 1-3 and all control valves V0 to Vn are closed (step L3), B is set to-1, the process returns to step S2, and if TJ is larger than SD2, the process returns to step S2 directly.
(6) And if the TJ is larger than or equal to SD1, sequentially calculating the absolute difference value of the temperature Ti (T1-Tn) of each layer corresponding to the water inlet of the heat collecting side of the hot water storage tank and the temperature Tc of the outlet water of the heat collector, and recording the absolute difference value as Tdi. (step S5)
(7) And comparing and obtaining the minimum value of Tdi, and recording the number of the corresponding heat storage water tank layers as m. (step S6)
(8) And judging whether B is equal to m or not. (step S7)
(9) If B is equal to m, the process returns directly to step S2.
(10) If B is not equal to m, the sizes of C and SD3 are determined. (step S8)
(11) If C is greater than SD3, control valve VB is closed, and the process proceeds to step S10. (step S9)
(12) Control valve Vm is opened, B is set equal to m, timing is started and recorded as C. (step S10)
(12) If C is less than or equal to SD3, it is determined whether B is equal to "-1". (step L4)
If B is equal to "-1", starting the heat collection circulating water pump 1-3 and the control valve V0 (step L4), and then executing step S10; if B is not equal to "-1", the process returns directly to step S2.
(13) And judging whether the system receives a shutdown signal. (step S11)
(14) If the shutdown signal is received, the circulating pump and all the control valves are closed, and the circulation is finished. (step S12)
(15) If no shutdown signal is received, the process returns to step S2.

Claims (6)

1. A layered water inlet control method for a hot water storage tank of a solar water heating system is characterized by comprising the following steps:
1) dividing the heat storage water tank into n +1 temperature layers, wherein the n layers with water inlet ends positioned at the upper part of the heat storage water tank are respectively marked as 1 layer, 2 … layer, i layer and … n layer, and the water outlet ends are arranged at the bottommost layer of the heat storage water tank and are marked as 0 layer; additionally arranging temperature sensors in the water bodies of the temperature layers, and continuously monitoring the water temperatures of the temperature layers, wherein the water temperatures are respectively marked as T0, T1, T2 …, Ti and … Tn; simultaneously monitoring the water outlet temperature of the solar thermal collector and recording as Tc; the 1 st, 2 nd 2 … th, i th and … n layers of the water inlet end are respectively provided with valves V1 …, Vi and … Vn; the water outlet end is a 0 th layer and is provided with a valve V0;
2) when the difference Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is larger than the minimum opening temperature difference set value SD1, respectively comparing Tc with the water temperatures T1-Tn of the temperature layers from 1 to n in the hot water storage tank, judging the temperature layer with the minimum absolute difference, and recording the temperature layer with the minimum absolute difference as m;
a) if the current opening state inlet valve number B is not equal to m, and when the continuous operation time length C in the same state is less than or equal to the operation state transition minimum time length set value SD 3:
①, if B is-1, namely all valves at the water inlet end and the water outlet end are closed, and the heat collection circulating water pump is also closed, opening a water outlet pipeline valve V0 and a water inlet pipeline valve Vm at the bottom layer of the heat storage water tank, opening the heat collection circulating water pump, making B m, starting timing and recording as C;
②, if B ≠ -1, keeping the current switch states of all valves unchanged;
b) if the inlet valve number B of the current opening state is not equal to m, and when the continuous operation time length C of the same state is longer than SD3, closing the valve VB, opening the valve Vm, making B equal to m, starting timing and recording as C;
c) if the number B of the inlet valve in the current opening state is m, maintaining the current opening and closing states of all the valves unchanged;
3) when the difference Tc-T0 between the measured outlet water temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is not more than the minimum opening temperature difference set value SD 1:
a) if the number B of the inlet valve in the current opening state is not equal to-1, judging whether the difference value Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the heat storage water tank is smaller than a maximum closing temperature difference set value SD2, if so, closing all the valves V0 to Vn, closing the heat collection circulating water pump, and enabling B to be equal to-1;
b) if the number B of the inlet valve in the current opening state is equal to-1, continuously keeping the closing states of all the valves V0 to Vn unchanged, and continuously keeping the heat collection circulating water pump closed;
4) when the difference Tc-T0 between the measured water outlet temperature Tc of the solar heat collector and the bottom layer temperature T0 of the hot water storage tank is between the maximum closing temperature difference SD2 and the minimum opening temperature difference SD1, the switching state of a valve of the heat collecting system is kept unchanged, and the step 1) is returned; the temperature difference set value SD1 is in the range of 4.0-10.0 ℃, the range of SD2 is in the range of 1.0-5.0 ℃, SD1 is larger than SD2, and the difference between SD1 and SD2 is larger than 1.0 ℃.
2. The layered water inlet control method for the hot water storage tank of the solar water heating system according to claim 1, wherein the volume of the hot water storage tank is more than or equal to 600L.
3. The layered water inlet control method for the hot water storage tank of the solar water heating system according to claim 1, wherein the hot water storage tank is cylindrical, and the ratio of the height to the diameter of the cylindrical shape ranges from 3.0 to 4.0.
4. The layered water inlet control method for the hot water storage tank of the solar water heating system according to claim 3, wherein the number N of temperature layers of the hot water storage tank is in a range of 4-10 layers, and the height of each temperature layer is in a range of 0.1-0.4 m.
5. The layered water inlet control method for the hot water storage tank of the solar water heating system according to claim 1, wherein the set value SD3 is within a range of 30-120 seconds.
6. The layered water inlet control method for the hot water storage tank of the solar water heating system according to any one of claims 1 to 5, wherein the temperature measurement range of the temperature sensor is-20 ℃ to 100 ℃, and the temperature measurement precision is ± 0.1 ℃.
CN201710052042.3A 2017-01-20 2017-01-20 Layered water inlet control method for heat storage water tank of solar water heating system Active CN107796040B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2896145Y (en) * 2006-04-07 2007-05-02 中山市万径科技发展有限公司 Stratified-fluid solar heat-accumulated double-source heat pump central water-heating system
CN103047785A (en) * 2013-01-06 2013-04-17 芜湖贝斯特新能源开发有限公司 Stepless stratified hot water storage tank
CN103134186A (en) * 2013-03-18 2013-06-05 郏松筠 Multiple-cavity heat preservation water tank free of water mixing
JP2016223700A (en) * 2015-06-01 2016-12-28 株式会社Nttファシリティーズ Air conditioning system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2896145Y (en) * 2006-04-07 2007-05-02 中山市万径科技发展有限公司 Stratified-fluid solar heat-accumulated double-source heat pump central water-heating system
CN103047785A (en) * 2013-01-06 2013-04-17 芜湖贝斯特新能源开发有限公司 Stepless stratified hot water storage tank
CN103134186A (en) * 2013-03-18 2013-06-05 郏松筠 Multiple-cavity heat preservation water tank free of water mixing
JP2016223700A (en) * 2015-06-01 2016-12-28 株式会社Nttファシリティーズ Air conditioning system

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