阅读说明：本技术 一种低温热泵喷焓控制方法 (Low-temperature heat pump spray enthalpy control method ) 是由 王鹏 凌拥军 周锦杨 朱建军 于 2021-09-27 设计创作，主要内容包括：本发明涉公开了一种低温热泵喷焓控制方法,步骤如下：步骤1)：系统制热开机,判断喷焓电子膨胀阀是否满足开启条件；步骤2)：若满足,则根据环境温度和机组进水温度确定喷焓电子膨胀阀的初开度；步骤3)：喷焓电子膨胀阀保持当前初开度一段时间后,控制端根据排气目标温度和当前排气温度控制调节喷焓电子膨胀阀的步数；步骤4)：判断是否满足关闭喷焓电子膨胀阀条件。通过控制喷焓电子膨胀阀的开度来调节压缩机运行时的喷焓流量,这样就避免了系统在启动过程中由于压缩机的排温变化范围较小,并且可以在更短的时间内使压缩机的排气温度稳定,提高了系统在低温环境下的适应性和可靠性。(The invention discloses a method for controlling the injection enthalpy of a low-temperature heat pump, which comprises the following steps: step 1): the system is heated and started, and whether the enthalpy injection electronic expansion valve meets the opening condition is judged; step 2): if so, determining the initial opening degree of the enthalpy injection electronic expansion valve according to the ambient temperature and the water inlet temperature of the unit; step 3): after the enthalpy-injection electronic expansion valve keeps the current initial opening for a period of time, the control end controls and adjusts the step number of the enthalpy-injection electronic expansion valve according to the exhaust target temperature and the current exhaust temperature; step 4): and judging whether the conditions for closing the enthalpy injection electronic expansion valve are met. The enthalpy-spraying flow during the operation of the compressor is adjusted by controlling the opening degree of the enthalpy-spraying electronic expansion valve, so that the condition that the variation range of the exhaust temperature of the compressor is smaller in the starting process of the system is avoided, the exhaust temperature of the compressor can be stabilized in a shorter time, and the adaptability and the reliability of the system in a low-temperature environment are improved.)

1. The utility model provides a low temperature heat pump spouts enthalpy control method, be applied to heating system, heating system includes the control end, user side and heating end carry out the heat exchange through the heat exchanger, heating end is including the compressor that has the jet enthalpy function, the control end is through the aperture of the electronic expansion valve of the jet enthalpy of control compressor, thereby control and spout the enthalpy flow, reach the purpose of control compressor exhaust temperature, still include the exhaust sensor who is used for detecting compressor exhaust temperature, an ambient temperature sensor for detecting ambient temperature, a water temperature sensor for detecting the unit temperature of intaking that gets into the exchanger by the user side, the utility model is characterized in that: the enthalpy injection low-temperature heat pump control method comprises the following steps:

step 1): the system is heated and started, and whether the enthalpy injection electronic expansion valve meets the opening condition is judged; the opening conditions of the enthalpy injection electronic expansion valve comprise: firstly, the temperature Ta of the environment is less than or equal to 12 ℃; the exhaust temperature Td is more than or equal to the exhaust temperature range set by the enthalpy starting; the enthalpy of spraying is started and the set exhaust temperature range is 45-50 ℃; thirdly, the exhaust temperature Td is more than 40 ℃; the enthalpy-injection electronic expansion valve can be opened when the opening condition is met;

step 2): if so, determining the initial opening degree of the enthalpy injection electronic expansion valve according to the ambient temperature and the water inlet temperature of the unit; if not, the enthalpy injection electronic expansion valve is not opened;

step 3): after the enthalpy injection electronic expansion valve keeps the current initial opening to time, the step number of the enthalpy injection electronic expansion valve is dynamically adjusted by the control end, and the step number of the enthalpy injection electronic expansion valve is determined according to the exhaust target temperature and the current exhaust temperature of the compressor, so that the stable operation of the system is ensured; the value range of to is 20 s-30 s;

step 4): judging whether the conditions for closing the enthalpy injection electronic expansion valve are met or not; if so, closing the enthalpy injection electronic expansion valve; if not, entering the step 3) and continuously adjusting the step number of the enthalpy injection electronic expansion valve. The closing condition of the enthalpy injection electronic expansion valve comprises the following conditions: firstly, closing a compressor; secondly, defrosting the compressor; ③ the ambient temperature Ta is more than 13 ℃; the enthalpy-injection electronic expansion valve can be closed when any one closing condition is met.

2. The enthalpy control method for a low-temperature heat pump according to claim 1, characterized in that: in the step 2), the method for determining the initial opening of the enthalpy injection electronic expansion valve comprises the following steps: the initial opening degree is 8 xtwin-6 xTa-180; wherein Ta is the ambient temperature, and the unit inlet water temperature is Twin.

3. The enthalpy control method for a low-temperature heat pump according to claim 1, characterized in that: the opening degree of the enthalpy injection electronic expansion valve is minimum 40 and maximum 480.

4. The enthalpy control method for a low-temperature heat pump according to claim 1, characterized in that: in step 3), if the current exhaust temperature Td (n) -the exhaust temperature control target To is not more than the exhaust threshold beta; the enthalpy injection electronic expansion valve has the following adjusting steps:

(n) [ (a + B) × Δ T (n) — a × Δ T (n-1) ] + C [ < Δ T (n) -2 × Δ T (n-1) + Δt (n-2) ], (Δ u (n)) the result is rounded off by a whole number, where a is a constant and B is a constant; if I is the current exhaust temperature Td (n) -exhaust temperature control target To I > exhaust threshold β; the enthalpy injection electronic expansion valve is adjusted to have the step number of deltaS (n) ═ A deltaT (n) — A deltaT (n-1) + C [ -delta T (n) — 2 deltaT (n-1) + delta T (n-2) ], and the result of deltaS (n) is rounded off to be an integer, wherein C is a constant; where Δ t (n) is an exhaust temperature deviation, and Δ t (n) is td (n) -To; td (n-1) is an exhaust temperature before 1 detection period, Td (n-2) is an exhaust temperature before 2 detection periods, Δ T (n-1) is an exhaust temperature difference between an exhaust temperature Td (n) at the present time and an exhaust temperature Td (n-1) before 1 detection period, Δ T (n-1) ═ Td (n-1) -To, Δ T (n-2) is an exhaust temperature difference between an exhaust temperature Td (n) at the present time and an exhaust temperature Td (n-2) before 2 detection periods, and Δ T (n-2) ═ Td (n-2) -To.

5. The enthalpy control method for a low-temperature heat pump according to claim 4, characterized in that: the value range of A is 3-10; b is a constant, and the value range of B is 0.1-10; c is a constant, and the value range of C is 2-15; the value range of the exhaust threshold beta is 8-15 ℃.

6. The enthalpy control method for a low-temperature heat pump according to claim 4, characterized in that: the value range of the detection period is 40-90 s; if the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is larger, the value of the detection period is smaller; if the temperature difference between the current exhaust temperature td (n) and the exhaust temperature control target To is larger, the detection period value is larger.

Technical Field

The invention relates to the field of heating, in particular to a control method for enthalpy of low-temperature heat pump spray.

Background

The application of the low-temperature air source heat pump technology in the fields of air conditioning, heating and hot water greatly improves the life quality of human beings. At present, the application of the low-temperature air source heat pump technology in the industry mainly comprises two modes: one is spray liquid, high-temperature and high-pressure supercooled liquid is throttled and depressurized and then directly sprayed into an air suction port or a compressor medium-pressure interface, so that the heating capacity can be greatly improved, the exhaust temperature is reduced, and the running range of a unit is expanded; the other type is an economizer scheme, a plate heat exchanger or a flash evaporation cylinder is matched, a part of refrigerant is separated from a main path, and the refrigerant exchanges heat with the main path and evaporates in the economizer after throttling and then is sprayed into a compressor medium-pressure interface. Both modes may be collectively referred to as enthalpy injection. Because the low-temperature air source heat pump has a wide operation range, the enthalpy injection electronic expansion valves of part of manufacturers are unreasonably controlled, the exhaust temperature is fluctuated, and the system operation is unstable. Especially during start-up, the exhaust temperature oscillations fluctuate, which can lead to poor reliability of the overall system.

Disclosure of Invention

In order to solve the above problems, an object of the present invention is to provide a low temperature heat pump injection enthalpy control method for solving the problem of system instability due to discharge temperature at the time of compressor start-up.

In order to achieve the purpose, the invention adopts the following technical scheme: the heating system comprises a control end, a user end and a heating end, the user end and the heating end carry out heat exchange through a heat exchanger, the heating end comprises a compressor with an enhanced vapor injection function, the control end controls the opening of an electronic expansion valve for controlling the vapor injection of the compressor, thereby controlling the flow of the vapor injection, achieving the purpose of controlling the exhaust temperature of the compressor, and further comprises an exhaust sensor for detecting the exhaust temperature of the compressor, an environment temperature sensor for detecting the environment temperature, a water temperature sensor for detecting the water inlet temperature entering the exchanger from the user side, and a control method of the vapor injection comprises the following steps:

step 1): the system is heated and started, and whether the enthalpy injection electronic expansion valve meets the opening condition is judged; the opening conditions of the enthalpy injection electronic expansion valve comprise: firstly, the temperature Ta of the environment is less than or equal to 12 ℃; the exhaust temperature Td is more than or equal to the exhaust temperature range set by the enthalpy starting; the enthalpy of spraying is started to set a temperature exhaust range of 45-50 ℃; thirdly, the exhaust temperature Td is more than 40 ℃; the enthalpy-injection electronic expansion valve can be opened when the opening condition is met;

step 2): if so, determining the initial opening degree of the enthalpy injection electronic expansion valve according to the ambient temperature and the water inlet temperature of the unit; if not, the enthalpy injection electronic expansion valve is not opened;

step 3): after the enthalpy injection electronic expansion valve keeps the current initial opening to time, the step number of the enthalpy injection electronic expansion valve is dynamically adjusted by the control end, and the step number of the enthalpy injection electronic expansion valve is determined according to the exhaust target temperature and the current exhaust temperature of the compressor, so that the stable operation of the system is ensured; the value range of to is 20 s-30 s;

step 4): judging whether the conditions for closing the enthalpy injection electronic expansion valve are met or not; if so, closing the enthalpy injection electronic expansion valve; if not, entering the step 3), and continuously adjusting the step number of the enthalpy injection electronic expansion valve; the closing condition of the enthalpy injection electronic expansion valve comprises the following conditions: firstly, closing a compressor; secondly, defrosting the compressor; and the ambient temperature Ta is more than 13 ℃. The enthalpy-injection electronic expansion valve can be closed when any one closing condition is met;

preferably, in step 2), the method for determining the initial opening degree of the enthalpy injection electronic expansion valve is as follows: the initial opening degree is 8 xtwin-6 xTa-180; wherein Ta is the ambient temperature, and the unit inlet water temperature is Twin.

Preferably, the opening degree of the enthalpy injection electronic expansion valve is minimum 40 and maximum 480. Therefore, the upper limit and the lower limit of the opening of the enthalpy-spraying electronic expansion valve are set, the condition that the enthalpy-spraying electronic expansion valve is opened is met, the flow of the spraying enthalpy is guaranteed not to be too large or too small, and the effectiveness of the spraying enthalpy is guaranteed.

Preferably, in step 3), if the current exhaust temperature td (n) -the exhaust temperature control target toi ≦ the exhaust threshold β; the enthalpy injection electronic expansion valve is adjusted by the steps of delta U (n) (A + B) × delta T (n) (-A × delta T (n-1)) + C [. DELTA T (n) -2 × delta T (n-1) +. DELTA T (n-2) ], and the result of delta U (n) is rounded off by an integer. If I is the current exhaust temperature Td (n) -exhaust temperature control target To I > exhaust threshold β; the adjusting step number of the enthalpy injection electronic expansion valve is DeltaS (n) ═ A DeltaT (n) — A DeltaT (n-1) + C [. DELTA.T (n) — 2 DeltaT (n-1) + DeltaT (n-2) ], and the result of DeltaS (n) is rounded up to an integer; where Δ t (n) is an exhaust temperature deviation, and Δ t (n) is td (n) -To; td (n-1) is an exhaust temperature before 1 detection period, Td (n-2) is an exhaust temperature before 2 detection periods, Δ T (n-1) is an exhaust temperature difference between an exhaust temperature Td (n) at the present time and an exhaust temperature Td (n-1) before 1 detection period, Δ T (n-1) ═ Td (n-1) -To, Δ T (n-2) is an exhaust temperature difference between an exhaust temperature Td (n) at the present time and an exhaust temperature Td (n-2) before 2 detection periods, Δ T (n-2) ═ Td (n-2) -To, a is a constant, B is a constant, and C is a constant. In this way, in the process of the operation of the compressor, as the temperature difference between the current exhaust temperature td (n) and the exhaust temperature control target To is gradually reduced, the opening degree of the enthalpy-injection electronic expansion valve is also gradually reduced, so that the compressor is always ensured To be stably operated after being started.

Preferably, the value range of A is 3-10; b is a constant, and the value range of B is 0.1-10; c is a constant, and the value range of C is 2-15.

Preferably, the value range of the exhaust threshold beta is 8-15 ℃. As such, the compressor tends to or is in a steady state within this temperature range.

Preferably, the detection period ranges from 40s to 90 s; if the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is larger, the value of the detection period is smaller; if the temperature difference between the current exhaust temperature td (n) and the exhaust temperature control target To is larger, the detection period value is larger. Therefore, under the condition that the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is large, the enthalpy injection electronic expansion valve performs high-frequency adjustment, and under the condition that the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is small, the enthalpy injection electronic expansion valve performs low-frequency adjustment, so that the system can be stably started To reach the set target.

Compared with the traditional technical scheme, the technical scheme of the invention adjusts the enthalpy-injection flow rate when the compressor operates by controlling the opening of the enthalpy-injection electronic expansion valve, so that the problem that the exhaust temperature of the compressor is stable in a shorter time due to a smaller exhaust temperature change range of the compressor in the starting process of the system is avoided, the adaptability and the reliability of the system in a low-temperature environment are improved, and the probability of faults of the system, such as poor heating effect, halt and the like, is reduced.

Drawings

FIG. 1 is a schematic flow chart of a method for controlling enthalpy of injection of a low-temperature heat pump according to an embodiment of the present invention;

fig. 2 is a comparison diagram of peaks of the embodiment of the present invention with and without the technical solution of the present invention.

Reference numerals: 1. the variation curve of the exhaust temperature of the compressor when the technical scheme is not executed; 2. the variation curve 2 of the discharge temperature of the compressor when implementing the technical scheme.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Examples

Fig. 1 shows a method for controlling enthalpy injection of a low-temperature heat pump, which is applied to a heating system, wherein the heating system comprises a control end, a user end, a heating end and a heat exchanger. The heating end comprises a compressor with an enhanced vapor injection function, and the control end controls the flow of the vapor injection by controlling the opening of an electronic expansion valve for vapor injection of the compressor, so as to achieve the purpose of controlling the exhaust temperature of the compressor; the user side exchanges heat with the heating end through the heat exchanger. The system also comprises an exhaust sensor for detecting the exhaust temperature of the compressor, an ambient temperature sensor for detecting the ambient temperature, and a water temperature sensor for detecting the water inlet temperature of the unit entering the exchanger from the user side.

The control method of the low-temperature heat pump spray enthalpy comprises the following steps:

step 1): the system is heated and started, and whether the enthalpy injection electronic expansion valve meets the opening regulation or not is judged;

step 2): if so, determining the initial opening degree of the enthalpy injection electronic expansion valve according to the environment temperature and the unit water inlet temperature, and entering the step 3); if not, the electronic expansion valve is not opened;

step 3): after the enthalpy injection electronic expansion valve keeps the current initial opening to time, the step number of the enthalpy injection electronic expansion valve is dynamically adjusted by the control end, and the step number of the enthalpy injection electronic expansion valve is determined according to the exhaust target temperature and the current exhaust temperature of the compressor, so that the stable operation of the system is ensured; the value range of to is 20 s-30 s;

step 4): judging whether the conditions for closing the enthalpy injection electronic expansion valve are met or not; if so, closing the enthalpy injection electronic expansion valve; if not, entering the step 3) and continuously adjusting the step number of the enthalpy injection electronic expansion valve.

In this embodiment, in step 1), the opening condition of the enthalpy injection electronic expansion valve includes: firstly, the temperature Ta of the environment is less than or equal to 12 ℃; secondly, the exhaust temperature Td is more than or equal to the enthalpy of injection, and the set exhaust temperature is started (the value range is 45-50 ℃); thirdly, the exhaust temperature Td is more than 40 ℃; and the enthalpy injection electronic expansion valve can be opened by meeting the conditions.

In this embodiment, in the step 2), the method for determining the initial opening of the enthalpy-injection electronic expansion valve includes: the initial opening degree is 8 xtwin-6 xTa-180; wherein Ta is the environment temperature, and the unit water inlet temperature is Twin; the opening degree of the enthalpy injection electronic expansion valve is minimum 40 and maximum 480; and if the calculation result is less than 40, taking 40, and if the calculation result is more than 480, taking the value as 480. So for guarantee the unit when guaranteeing steady operation accelerate the heating efficiency of unit.

In this embodiment, in the step 3), the adjustment step number of the enthalpy injection electronic expansion valve is determined as follows: Δ t (n) is an exhaust temperature deviation, Δ t (n) is td (n) -To, td (n) is an exhaust temperature at the present time, and To is an exhaust temperature control target; td (n-1) is the exhaust temperature before 1 detection period, and the exhaust temperature difference between the exhaust temperature Td (n) at the current moment and the exhaust temperature Td (n-1) before 1 detection period is delta T (n-1) -Td (n-1) -To; td (n-2) is the exhaust temperature before 2 detection periods, and the exhaust temperature difference between the exhaust temperature Td (n) at the current moment and the exhaust temperature Td (n-2) before 2 detection periods is as follows: Δ T (n-2) ═ Td (n-2) -To. The value range of the detection period is 40-90 s, and the larger the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is, the smaller the value of the detection period is; the larger the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is, the smaller the temperature difference is, and the larger the detection period value is; like this, because among the prior art, can realize spouting fast regulation and the regulation slowly of enthalpy electronic expansion valve, guarantee the stable output of compressor in the operation process, avoid in low temperature environment because the too big compression and the unstability that leads to of the difference in temperature between exhaust temperature and the ambient temperature, improve the life of compressor, reduce the compressor energy consumption. In this embodiment, if the current exhaust temperature Td (n) -the exhaust temperature control target To is not greater than the exhaust threshold β (in the range of 8-15 ℃); the enthalpy injection electronic expansion valve is adjusted by the steps of delta U (n) (A + B) × delta T (n) (-A × delta T (n-1)) + C [. DELTA T (n) -2 × delta T (n-1) +. DELTA T (n-2) ], and the result of delta U (n) is rounded off by an integer. If the current exhaust temperature Td (n) -the exhaust temperature control target To > the exhaust threshold beta (range is 8-15 ℃); the enthalpy injection electronic expansion valve is adjusted to the step number of deltaS (n) ═ A deltaT (n) — A deltaT (n-1) + C [ -delta T (n) — 2 deltaT (n-1) + delta T (n-2) ], and the result of deltaS (n) is rounded to an integer. Wherein A is a constant, and the value range of A is 3-10; b is a constant, and the value range of B is 0.1-10; c is a constant, and the value range of C is 2-15. The adjusting steps of the enthalpy injection electronic expansion valve are only related to three temperatures of the current exhaust temperature Td (n), the exhaust temperature T (n-1) of the exhaust temperature before 1 detection period and the exhaust temperature Td (n-2) of the exhaust temperature before 2 detection periods. Thus, under the condition that the detection periods are the same, if the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is larger, the number of steps regulated by the enthalpy injection electronic expansion valve is larger; if the temperature difference between the current exhaust temperature Td (n) and the exhaust temperature control target To is smaller, the step number regulated by the enthalpy injection electronic expansion valve is smaller; so set up, can control the step number that the enthalpy-injection electronic expansion valve was adjusted within reasonable scope, guarantee the steady operation of compressor, guarantee the stable promotion of temperature.

In this embodiment, in the step 4), the closing condition of the enthalpy injection electronic expansion valve includes: firstly, closing a compressor; secondly, defrosting the compressor; ③ the ambient temperature Ta is more than 13 ℃; and the enthalpy injection electronic expansion valve can be closed when any one closing condition is met. Therefore, after the exhaust temperature Td and the ambient temperature Ta reach the target values, the enthalpy injection electronic expansion valve is closed, so that the energy consumption is reduced, and the purposes of energy conservation and emission reduction are achieved.

As shown in fig. 2, the operation time is shown in the horizontal direction in fig. 2, and the exhaust temperature, exhaust pressure, exhaust humidity, or the like may be shown in the vertical direction; in the curves in fig. 2, taking the variation curve 1 of the discharge temperature of the compressor when the technical scheme is not executed and the variation curve 2 of the discharge temperature of the compressor when the technical scheme is executed as an example, comparing the variation curve 1 of the discharge temperature of the compressor when the technical scheme is not executed with the variation curve 2 of the discharge temperature of the compressor when the technical scheme is executed, it can be seen that the discharge temperature of the compressor can quickly reach a stable state after the technical scheme is executed, so that it can be proved that the traditional technical scheme is distinguished, the scheme can make the compressor quickly stable, make the unit quickly warm up, and increase the reliability and the adaptability of the system.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.