Dual-condition self-adaptive balancing valve and control method thereof

Abstract

The embodiment of the present invention discloses a dual-condition self-adaptive balancing valve and a control method thereof, wherein the balancing valve comprises a valve body, an electric operating mechanism, a controller, a pressure difference sensor, and a temperature sensor, wherein the pressure difference sensor and the temperature sensor are respectively used for two-pipe detection of the pressure and temperature in the supply and return water pipes of the HVAC water system branch; the controller selects to enable the cooling mode or the heating mode according to the current month and the temperature fed back by the temperature sensor. The present invention adjusts the hydraulic balance of the two-pipe HVAC system in the layer according to the temperature of the heat transfer medium, so that the two-pipe HVAC system can meet the cooling and heating needs throughout the year, avoids uneven cooling and heating on the same floor, improves the user's comfort, and reduces the energy waste caused by meeting the most unfavorable cooling (heating) conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of heating, ventilation and air conditioning, and in particular to a dual-operating-condition self-adaptive balancing valve and a control method thereof. Background Art

[0002] Compared with ordinary split air conditioners, central air conditioning systems are widely used in public buildings and high-end residential buildings because of their high energy efficiency and convenient centralized monitoring. Central air conditioning systems can be divided into two-pipe and four-pipe systems according to the form of control. In the two-pipe system, the refrigerant and heat medium pipelines use the same pipeline system when operating in winter and summer, that is, hot water and return water in winter, and chilled water (and return water) are transported by the same pipeline in summer. The switching of the cold and hot sources is carried out in the chilled water pump room and heat exchange station. The four-pipe system uses separate cold and hot water supply and return pipe systems, and conversion control valves are installed on the inlet and outlet pipes. It is mainly an air conditioning system for year-round use, that is, there are cold sources and heat sources available at any time, and the conversion valve is controlled by the temperature control valve to adjust the cold and hot water volume. The two-pipe system is the most widely used control method in HVAC because of its low investment cost and low maintenance.

[0003] HVAC systems often use a two-pipe system to meet the building's summer cooling and winter heating needs. Cold water is supplied in the water pipes in the summer, and hot water is supplied in the water pipes in the winter to meet the cooling and heating needs of the terminal air conditioning equipment. However, the cooling and heating needs of buildings show different characteristics. The area with the greatest cooling demand in the summer is in the southwest, while the area with the greatest heating demand in the winter is in the north. This creates a contradiction: when the two-pipe water system is hydraulically balanced according to the summer demand, the same setting will cause overheating in the west-south area and overcooling in the north-facing rooms in winter; if it is balanced according to the winter demand, the west-south rooms will overheat in the summer. At present, there is no good solution to this problem.

[0004] The cold and hot media of the two-pipe air-conditioning system share a set of pipe systems, but there are regional differences in cold and hot demands between layers. For example, the area with the greatest cold demand is in the southwest, while the area with the greatest heat demand in winter is in the north. After hydraulic balance is performed for a certain working condition (heating or cooling), hydraulic imbalance occurs in another working condition, resulting in the two-pipe air-conditioning system being unable to meet the air-conditioning system needs throughout the year. This is also the biggest disadvantage of the two-pipe system. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a dual-condition self-adaptive balancing valve and a control method thereof to meet the cooling and heating needs throughout the year and avoid uneven cooling and heating on the same floor.

[0006] In order to solve the above technical problems, the embodiment of the present invention proposes a dual-condition self-adaptive balancing valve, which is applied to a two-pipe HVAC system, and includes a valve body, an electric operating mechanism, a controller, a pressure difference sensor, and a temperature sensor connected to the controller. The pressure difference sensor and the temperature sensor are respectively used for two-pipe detection of the pressure and temperature in the supply and return water pipes of the HVAC water system branch;

[0007] The controller selects to enable cooling mode or heating mode according to the current month and the temperature feedback from the temperature sensor. In cooling mode, the controller selects to enable cooling mode or heating mode according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to make the two-pipe HVAC system hydraulically balanced; in the heating mode, according to the preset initial heating setting value V hot Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to achieve hydraulic balance of the two-pipe HVAC system branch.

[0008] Furthermore, the branch flow setting value and the pressure difference setting value are calculated according to the following formula:

[0009]

[0010]

[0011] P set =S*Q set 2 ;

[0012] Among them, M set is the branch mass flow setpoint, Q t The design load for the area that the branch is responsible for, C p is the constant pressure specific heat capacity of water, Δt is the supply and return water temperature difference, Q set is the branch volume flow setting value, ρ is the water density, P set is the branch pressure difference setting value, and S is the branch comprehensive resistance coefficient.

[0013] Furthermore, the controller activates the heating mode only in the preset heating month, the heating mode is activated when the feedback temperature T≥30°C, and the cooling mode is activated when the feedback temperature T<30°C.

[0014] Accordingly, an embodiment of the present invention further provides a control method for a dual-condition self-adaptive balancing valve, comprising:

[0015] Step 1: Determine whether the current time is in the preset heating month. If not, select to enable the cooling mode. If yes, proceed to step 2;

[0016] Step 2: Determine whether the temperature fed back by the current temperature sensor is less than 30°C. If so, enable the cooling mode; if not, enable the heating mode.

[0017] Furthermore, in the cooling mode, according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to make the two-pipe HVAC system hydraulically balanced; in the heating mode, according to the preset initial heating setting value V hot Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to achieve hydraulic balance of the two-pipe HVAC system branch.

[0018] Furthermore, the branch flow setting value and the pressure difference setting value are calculated according to the following formula:

[0019]

[0020]

[0021] P set =S*Q set 2 ;

[0022] Among them, M set is the branch mass flow setpoint, Q t The design load for the area that the branch is responsible for, C p is the constant pressure specific heat capacity of water, Δt is the supply and return water temperature difference, Q set is the branch volume flow setting value, ρ is the water density, P set is the branch pressure difference setting value, and S is the branch comprehensive resistance coefficient.

[0023] The beneficial effects of the present invention are as follows: the present invention performs hydraulic balance adjustment on the two-pipe HVAC system within the layer according to the temperature of the heat transfer medium, so that the two-pipe HVAC system can meet the cooling and heating needs throughout the year, avoid uneven cooling and heating on the same floor, improve user comfort, and reduce energy waste caused by meeting the most unfavorable cooling (heating) conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram of the principle of a two-pipe HVAC system.

[0025] Figure 2 It is a flow chart of a control method of a dual-condition self-adaptive balancing valve according to an embodiment of the present invention.

[0026] Description of Figure Numbers

[0027] 1- water supply main pipe, 2- water collection pipe, 3- electric valve, 4- fan coil unit, 5- temperature sensor, 6- differential pressure balancing valve, 7- static balancing valve. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0029] The dual-mode self-adaptive balancing valve of the embodiment of the present invention comprises a valve body, an electric operating mechanism, a controller, a pressure difference sensor and a temperature sensor connected to the controller. The pressure difference sensor and the temperature sensor are used to detect the pressure and temperature in the supply and return pipes of the HVAC water system branch respectively.

[0030] The present invention is applied to a two-pipe HVAC system, please refer to Figure 1-2 The dual-condition self-adaptive balancing valve of the present invention adds a temperature sensor to the existing dynamic (flow or pressure difference) balancing valve (dynamic flow balancing valve is also called self-operated flow control valve, self-operated balancing valve, constant flow valve, automatic balancing valve, etc. It automatically changes the resistance coefficient according to the changes in the system working conditions. Within a certain pressure difference range, it can effectively control the flow passing through to maintain a constant value, that is, when the pressure difference before and after the valve increases, the automatic closing action of the valve can keep the flow from increasing. On the contrary, when the pressure difference decreases, the valve automatically opens and the flow remains constant. This valve can adjust the flow setting value through manual or electric actuators. This setting value is generally a volume flow rate.) products. The controller adds two settings, one is the cooling mode setting value, and the other is the heating mode setting value. When the temperature sensor senses that the water pipe of the branch supplies cold water, the cooling mode is enabled, and the balancing valve automatically operates according to the cooling valve position setting value; when it senses that the water pipe supplies hot water, the heating mode is enabled, and the balancing valve automatically operates according to the heating valve position setting value.

[0031] The dual-mode self-adjusting balancing valve of the present invention is installed at the same position as the balancing valve of the conventional two-pipe HVAC system in the art. The present invention can realize the water system balance under the dual-mode operation of cooling and heating.

[0032] The controller selects to enable cooling mode or heating mode according to the current month and the temperature feedback from the temperature sensor. The controller of the present invention is provided with two control modes. In the cooling mode, according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, adjust the valve body in real time according to the calculation results, realize dynamic flow control function, and make the two-pipe HVAC system hydraulically balanced; in heating mode, according to the preset initial heating setting value Vhot Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, adjust the valve body in real time according to the calculation results, realize the dynamic flow control function, and make the two-pipe HVAC system branch hydraulically balanced. The present invention calculates the pressure difference or flow setting value under the two working conditions according to the cooling demand under the cooling condition in summer and the heat demand under the heating condition in winter, or determines the pressure difference or flow setting value under the two working conditions by means of air conditioning system adjustment. The specific valve position of the present invention will change continuously in order to maintain the set value unchanged. For example, when the main pipe flow changes, the dynamic balancing valve on the branch pipe will automatically open and close to maintain the flow or pressure difference of the branch pipe unchanged.

[0033] V cold V hot It is determined by the horizontal balance adjustment calculation or adaptation. It is the same as the valve position setting value determination process of the existing single-condition dynamic balancing valve. Different projects have different values. For example, the pressure difference of the dynamic pressure differential balancing valve of branch pipe 1 in project A is set to P after the horizontal balance design calculation or air conditioning system adjustment. set =200Pa, V is used here cold V hot The setting value of the dual-condition self-adjusting balancing valve is because the balancing valve can be a pressure differential balancing valve or a flow balancing valve, and the setting value can be a pressure differential setting value (P set ), or it can be the flow setting value (Q set ).

[0034] As an implementation method, the branch flow setting value and the pressure difference setting value are calculated according to the following formula:

[0035]

[0036]

[0037] P set =S*Q set 2 ;

[0038] Among them, M set is the branch mass flow setting value (kg / s), Q t is the design load of the branch area (W), C p is the constant pressure specific heat capacity of water (J / kg·℃), Δt is the supply and return water temperature difference, generally 5℃(℃), Q set is the branch volume flow setting value (m3 / s), ρ is the water density (kg / m 3 ), P set is the branch pressure difference setting value (Pa), S is the branch comprehensive resistance coefficient (kg / m 7 ).

[0039] As an implementation method, a timing device is provided in the controller, and the controller enables the heating mode only in the preset heating months. The heating mode is enabled when the feedback temperature T≥30℃, and the cooling mode is enabled when the feedback temperature T<30℃. In order to avoid the malfunction of the differential pressure balancing valve caused by the water temperature in the water supply pipe exceeding 30℃ in extreme summer conditions, a timing device is provided in the controller, and the heating mode can only be used in the heating months (such as November, December, January, February, and March).

[0040] Please refer to Figure 2 The control method of the dual-condition self-adaptive balancing valve according to the embodiment of the present invention comprises:

[0041] Step 1: Determine whether the current time is in the preset heating month. If not, select to enable the cooling mode. If yes, proceed to step 2;

[0042] Step 2: Determine whether the temperature fed back by the current temperature sensor is less than 30°C. If so, enable the cooling mode; if not, enable the heating mode.

[0043] As an implementation method, in the cooling mode, according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to make the two-pipe HVAC system hydraulically balanced; in the heating mode, according to the preset initial heating setting value V hot Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to achieve hydraulic balance of the two-pipe HVAC system branch.

[0044] As an implementation method, the branch flow setting value and the pressure difference setting value are calculated according to the following formula:

[0045]

[0046]

[0047] P set =S*Q set 2 ;

[0048] Among them, M set is the branch mass flow setpoint, Q t The design load for the area that the branch is responsible for, C p is the constant pressure specific heat capacity of water, Δt is the supply and return water temperature difference, Q set is the branch volume flow setting value, ρ is the water density, P set is the branch pressure difference setting value, and S is the branch comprehensive resistance coefficient.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-mode self-adaptive balancing valve, used in a two-pipe HVAC system, comprising a valve body, an electric operating mechanism, a controller, and a pressure differential sensor, characterized in that: It also includes a temperature sensor connected to the controller, a pressure difference sensor and a temperature sensor for respectively detecting the pressure and temperature in the supply and return water pipes of the HVAC water system branch with two pipes; The controller selects to enable cooling mode or heating mode according to the current month and the temperature feedback from the temperature sensor. In cooling mode, the controller selects to enable cooling mode or heating mode according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to make the hydraulic balance of the two-pipe HVAC system; in the heating mode, according to the preset initial heating setting value V hot Adjust the opening, calculate the branch flow set value and pressure difference set value in real time, and adjust the valve body in real time according to the calculation results to achieve hydraulic balance of the two-pipe HVAC system branch; Calculate the branch flow setting value and pressure difference setting value according to the following formula: ； ； ； in, is the branch mass flow setting value, its unit is kg / s; The design load for the area covered by the branch, in W; is the specific heat capacity of water at constant pressure, with the unit being J / kg▪℃; is the supply and return water temperature difference, the unit is ℃; is the branch volume flow setting value, its unit is m³ / s; is the density of water, its unit is kg / m³; It is the branch pressure difference setting value, and its unit is Pa; is the comprehensive resistance coefficient of the branch, its unit is kg / m 7 .

2. The dual-mode self-adaptive balancing valve according to claim 1, characterized in that: The controller only enables the heating mode in the preset heating months. When the feedback temperature T≥30℃, the heating mode is enabled, and when the feedback temperature T<30℃, the cooling mode is enabled.

3. A control method for a dual-mode self-adaptive balancing valve according to any one of claims 1 to 2, characterized in that: include: Step 1: Determine whether the current time is in the preset heating month. If not, select to enable cooling mode. If yes, proceed to step 2. Step 2: Determine whether the temperature fed back by the current temperature sensor is less than 30°C. If so, enable the cooling mode; if not, enable the heating mode; In cooling mode, according to the preset initial cooling valve position setting value V cold Adjust the opening, calculate the branch flow setting value and pressure difference setting value in real time, and adjust the valve body in real time according to the calculation results to make the hydraulic balance of the two-pipe HVAC system; in the heating mode, according to the preset initial heating setting value V hot Adjust the opening, calculate the branch flow set value and pressure difference set value in real time, and adjust the valve body in real time according to the calculation results to achieve hydraulic balance of the two-pipe HVAC system branch; Calculate the branch flow setting value and pressure difference setting value according to the following formula: ； ； ； in, is the branch mass flow setting value, its unit is kg / s; The design load for the area covered by the branch, in W; is the specific heat capacity of water at constant pressure, with the unit being J / kg▪℃; is the supply and return water temperature difference, the unit is ℃; is the branch volume flow setting value, its unit is m³ / s; is the density of water, its unit is kg / m³; It is the branch pressure difference setting value, and its unit is Pa; is the comprehensive resistance coefficient of the branch, its unit is kg / m 7 .

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