A method for controlling target exhaust temperature in heating mode

Abstract

This invention discloses a method for controlling the target exhaust temperature in heating mode. When the unit starts for heating, the startup steps include: Step 1): The electronic expansion valve is reset and opened to its initial opening degree, and the water pump is turned on simultaneously, continuously monitoring the return water temperature and the water flow switch; Step 2): After the water flow switch is continuously closed for 30 seconds, the outdoor fan is turned on; Step 3): The compressor is turned on after 10 seconds. After the compressor starts and the electronic expansion valve maintains its initial opening degree for 3 minutes, the startup control stage begins; when the startup control stage running time t≥15 minutes or Pdt-Tout n If the temperature exceeds 5°C, the system enters the operation control phase. This invention incorporates a steadily rising outlet water temperature into the target exhaust temperature calculation formula, thus preventing a sharp increase in the target exhaust temperature.

Description

Technical Field

[0001] This invention relates to a method for controlling the target exhaust temperature in a heating mode. Background Technology

[0002] In heat pump systems that use target exhaust temperature as the electronic expansion valve control method, the actual exhaust temperature is mainly related to the compressor frequency, condensing temperature, and evaporating temperature. Therefore, the control of the target exhaust temperature is based on these three parameters. The higher the compressor frequency, the higher the target exhaust temperature, and vice versa; the higher the condensing temperature, the higher the target exhaust temperature, and vice versa; the higher the evaporating temperature, the lower the target exhaust temperature, and vice versa.

[0003] In practical applications, considering cost and the reliability of the entire system, the evaporation temperature is replaced by the ambient temperature detected by the sensor during heating mode, and the condensation temperature is replaced by the temperature converted from the high-pressure side pressure detected by the pressure sensor. However, in actual experimental tests, especially when heating at low ambient temperatures, the evaporation effect is poor and the system response is slow due to the low ambient temperature on the evaporation side. If the target exhaust temperature is higher than the actual exhaust temperature, the electronic expansion valve is in the closed state to achieve the purpose of increasing the actual exhaust temperature to reach the target exhaust temperature.

[0004] When the electronic expansion valve is closed, the high-pressure side pressure rises immediately, and the target exhaust temperature increases. However, the actual exhaust temperature response is delayed, leading to the electronic expansion valve continuously closing and the high-pressure side pressure rising continuously. When the electronic expansion valve is closed to a certain extent, the high-pressure side pressure rises sharply, eventually causing the unit's high-pressure protection, or causing the compressor to reduce its frequency due to excessive high pressure, or when the actual exhaust temperature begins to respond, the electronic expansion valve is in a state of insufficient opening and cannot open wide enough, resulting in a sharp rise in the actual exhaust temperature and triggering a series of adverse situations such as exhaust high temperature protection. In addition, excessive high-pressure side pressure will also cause high power consumption and high system power consumption. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for controlling the target exhaust temperature in a heating mode. In a system that uses the target exhaust temperature as the control method, the outlet water temperature is incorporated into the calculation of the target exhaust temperature, effectively solving the problems of high-temperature exhaust protection, high-pressure protection, frequency reduction, and high system power consumption.

[0006] The technical solution adopted in this invention is:

[0007] A method for controlling the target exhaust temperature in heating mode.

[0008] When the unit starts up for heating, the startup procedure includes:

[0009] Step 1): Reset the electronic expansion valve and open it to the initial opening degree, and at the same time start the water pump, continuously monitor the return water temperature and water flow switch;

[0010] Step 2): After the water flow switch has been continuously closed for 30 seconds, turn on the outdoor fan;

[0011] Step 3): After 10 seconds, start the compressor. After the compressor starts and the electronic expansion valve maintains its initial opening for 3 minutes, it enters the start-up control stage.

[0012] The start-up control phase has a Δt = 2, and the start-up control phase includes the following steps:

[0013] When Tao ≤ 0℃:

[0014] If Tin n If the temperature is ≤40℃, the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0015] If Tin n For temperatures >40℃, select Tpo1 or Tpo2 based on the different condensation temperatures: if Pdt ≥ Tout n The target exhaust temperature calculation formula is executed according to Tpo2. If Pdt < Tout n Then the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0016] When Tao > 0℃, the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0017] When the startup control phase running time t≥15min or Pdt-Tout n If the temperature exceeds 5℃, the system will enter the operation control phase.

[0018] The target exhaust temperature during the operation control phase is set according to Tpo2, and Δt is adjustable. The initial value of Δt is 2, and the process includes the following steps:

[0019] After entering the operation control phase, the return water temperature during the operation control phase is recorded at 5-minute intervals.

[0020] Tin, when Tin n At ≤45℃:

[0021] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt+1 until Δt = 5 and no longer increases;

[0022] If 12.5% ​​≤ (Tin) n -Tin n-1 ) / Tin n-1If the value is less than 15%, then control Δt to maintain the current parameter.

[0023] If (Tin) n -Tin n-1 ) / Tin n-1 If ≤15%, then control Δt-1 until Δt=2 no longer decreases when Tin n When the temperature is >45℃:

[0024] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 10%, then control Δt+1 until Δt = 5 and no longer increases;

[0025] If 10% ≤ (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt to maintain the current parameter.

[0026] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is ≤12.5%, then control Δt-1 until Δt=2 no longer decreases;

[0027] The definitions are as follows: Pd is the high-pressure side pressure, Pdt is the condensation temperature converted from the high-pressure side pressure, and Tin... n Tin is the current return water temperature. n-1 Tout is the temperature of the previous return water. n The current outlet water temperature is given by Tpo1, where Tao is the ambient temperature, and Δt is the outlet water temperature correction coefficient. The target exhaust temperature is calculated using the formulas Tpo1 and Tpo2: Tpo1 = A * compressor frequency + B + C * Pdt - D * Tao + E, Tpo2 = A * compressor frequency + B + C * (Tout) * Pdt - D * Tao + E. n +Δt)-D*Tao+E, where A, B, C, D, and E are coefficients, with A in ℃ / Hz and B and E in ℃.

[0028] Preferably, A, B, C, D, and E are adjustable coefficients. Adjustable coefficient A includes A1-A5, B includes B1-B5, C includes C1-C5, D includes D1-D5, and E includes E1-E5. Their specific values ​​are adjusted according to the table below:

[0029] coefficient type Interval range Corresponding coefficient value A Compressor frequency < 45Hz A1=4% 45Hz ≤ compressor frequency < 60Hz A2=4% 60Hz ≤ compressor frequency < 75Hz A3=3% 75Hz ≤ compressor frequency < 90Hz A4=3% Compressor frequency ≥90Hz A5=3% B Compressor frequency < 45Hz B1=3 45Hz ≤ compressor frequency < 60Hz B2=3 60Hz ≤ compressor frequency < 75Hz B3=3 75Hz ≤ compressor frequency < 90Hz B4=4 Compressor frequency ≥90Hz B5=4 C Ambient temperature < -15℃ C1=115% -15℃≤Ambient temperature<-5℃ C2=115% -5℃≤Ambient temperature<5℃ C3=120% 5℃≤Ambient temperature<15℃ C4=120% Ambient temperature ≥15℃ C5=120% D Ambient temperature < -15℃ D1=15% -15℃≤Ambient temperature<-5℃ D2=15% -5℃≤Ambient temperature<5℃ D3=15% 5℃≤Ambient temperature<15℃ D4=15% Ambient temperature ≥15℃ D5=15% E Ambient temperature < -15℃ E1=25 -15℃≤Ambient temperature<-5℃ E2=22 -5℃≤Ambient temperature<5℃ E3=22 5℃≤Ambient temperature<15℃ E4=20 Ambient temperature ≥15℃ E5=20

[0030] Adjustable coefficients A and B are selected based on the current compressor frequency range (e.g., select A2 and B2 when the compressor frequency is 50Hz); adjustable coefficients C, D, and E are selected based on the current ambient temperature (Tao) range (e.g., select C3, D3, and E3 when Tao=0℃); after selecting a single coefficient value, substitute it into the target exhaust temperature calculation formula (Tpo1 or Tpo2).

[0031] Preferably, the initial opening degree of the electronic expansion valve is adjusted according to the ambient temperature. If Tao < -15℃, the initial opening degree of the electronic expansion valve is 140 steps; if -15 ≤ Tao < 0℃, the initial opening degree of the electronic expansion valve is 180 steps; if 0 ≤ Tao < 15℃, the initial opening degree of the electronic expansion valve is 280 steps; and if Tao ≥ 15℃, the initial opening degree of the electronic expansion valve is 360 steps.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. Incorporate the steadily rising outlet water temperature into the calculation formula for the target exhaust temperature to avoid a sudden increase in the target exhaust temperature;

[0034] 2. When in the "start-up control phase", switch between the "condenser target exhaust temperature calculation formula" and the "outlet water temperature target exhaust temperature" according to different situations to ensure rapid water temperature rise, while preventing exhaust high temperature protection when starting at low ambient temperature and high water temperature.

[0035] 3. When in the "operation control phase", optimize the target exhaust temperature according to the rate of increase of the return water temperature to ensure the stability of the target exhaust temperature and the energy efficiency and performance of the system. Attached Figure Description

[0036] Figure 1 This illustrates a heat pump system that uses the target exhaust temperature as a control method. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0038] like Figure 1 For a heat pump system that uses target exhaust temperature as a control method, this invention discloses a method for controlling the target exhaust temperature in heating mode.

[0039] When the unit starts up for heating, the startup procedure includes:

[0040] Step 1): Reset the electronic expansion valve and open it to the initial opening degree, and at the same time start the water pump, continuously monitor the return water temperature and water flow switch;

[0041] Step 2): After the water flow switch has been continuously closed for 30 seconds, turn on the outdoor fan;

[0042] Step 3): After 10 seconds, start the compressor. After the compressor starts and the electronic expansion valve maintains its initial opening for 3 minutes, it enters the start-up control stage.

[0043] The start-up control phase has a Δt = 2, and the start-up control phase includes the following steps:

[0044] When Tao ≤ 0℃:

[0045] If Tin n If the temperature is ≤40℃, the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0046] If Tin n For temperatures >40℃, select Tpo1 or Tpo2 based on the different condensation temperatures: if Pdt ≥ Tout n The target exhaust temperature calculation formula is executed according to Tpo2. If Pdt < Tout n Then the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0047] When Tao > 0℃, the target exhaust temperature calculation formula shall be executed according to Tpo1;

[0048] When the startup control phase running time t≥15min or Pdt-Tout n If the temperature exceeds 5℃, the system will enter the operation control phase.

[0049] The target exhaust temperature during the operation control phase is set according to Tpo2, and Δt is adjustable. The initial value of Δt is 2, and the process includes the following steps:

[0050] After entering the operation control phase, the return water temperature during the operation control phase is recorded at 5-minute intervals.

[0051] Tin, when Tin n At ≤45℃:

[0052] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt+1 until Δt = 5 and no longer increases;

[0053] If 12.5% ​​≤ (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 15%, then control Δt to maintain the current parameter.

[0054] If (Tin) n -Tin n-1) / Tin n-1 If ≤15%, then control Δt-1 until Δt=2 no longer decreases when Tin n When the temperature is >45℃:

[0055] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 10%, then control Δt+1 until Δt = 5 and no longer increases;

[0056] If 10% ≤ (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt to maintain the current parameter.

[0057] If (Tin) n -Tin n-1 ) / Tin n-1 If the value is ≤12.5%, then control Δt-1 until Δt=2 no longer decreases;

[0058] The definitions are as follows: Pd is the high-pressure side pressure, Pdt is the condensation temperature converted from the high-pressure side pressure, and Tin... n Tin is the current return water temperature. n-1 Tout is the temperature of the previous return water. n The current outlet water temperature is given by Tpo1, where Tao is the ambient temperature, and Δt is the outlet water temperature correction coefficient. The target exhaust temperature is calculated using the formulas Tpo1 and Tpo2: Tpo1 = A * compressor frequency + B + C * Pdt - D * Tao + E, Tpo2 = A * compressor frequency + B + C * (Tout) * Pdt - D * Tao + E. n +Δt)-D*Tao+E, where A, B, C, D, and E are adjustable coefficients. The unit of A is ℃ / Hz, and the units of B and E are ℃. The adjustable coefficients A include A1-A5, B includes B1-B5, C includes C1-C5, D includes D1-D5, and E includes E1-E5. Their specific values ​​are adjusted according to the table below:

[0059] coefficient type Interval range Corresponding coefficient value A Compressor frequency < 45Hz A1=4% 45Hz ≤ compressor frequency < 60Hz A2=4% 60Hz ≤ compressor frequency < 75Hz A3=3% 75Hz ≤ compressor frequency < 90Hz A4=3% Compressor frequency ≥90Hz A5=3% B Compressor frequency < 45Hz B1=3 45Hz ≤ compressor frequency < 60Hz B2=3 60Hz ≤ compressor frequency < 75Hz B3=3 75Hz ≤ compressor frequency < 90Hz B4=4 Compressor frequency ≥90Hz B5=4 C Ambient temperature < -15℃ C1=115% -15℃≤Ambient temperature<-5℃ C2=115% -5℃≤Ambient temperature<5℃ C3=120% 5℃≤Ambient temperature<15℃ C4=120% Ambient temperature ≥15℃ C5=120% D Ambient temperature < -15℃ D1=15% -15℃≤Ambient temperature<-5℃ D2=15% -5℃≤Ambient temperature<5℃ D3=15% 5℃≤Ambient temperature<15℃ D4=15% Ambient temperature ≥15℃ D5=15% E Ambient temperature < -15℃ E1=25 -15℃≤Ambient temperature<-5℃ E2=22 -5℃≤Ambient temperature<5℃ E3=22 5℃≤Ambient temperature<15℃ E4=20 Ambient temperature ≥15℃ E5=20

[0060] Adjustable coefficients A and B are selected according to the current compressor frequency range (e.g., when the compressor frequency is 50Hz, select A2 and B2); adjustable coefficients C, D, and E are selected according to the current ambient temperature (Tao) range (e.g., when Tao=0℃, select C3, D3, and E3); after selecting a single coefficient value, it is substituted into the target exhaust temperature calculation formula (Tpo1 or Tpo2) of claim 1.

[0061] Tin n ≤45℃ and Tinn >45℃, all conditions have an adjustable parameter Δt, but Tin n At temperatures above 45℃, the condensing temperature is high, resulting in poor heating performance. Considering system energy conservation, the adjustable parameters for each condition should, in principle, be higher than Tin. n The temperature should be kept low, ≤45℃.

[0062] The initial opening degree of the electronic expansion valve is adjusted according to the ambient temperature. If Tao < -15℃, the initial opening degree of the electronic expansion valve is 140 steps; if -15 ≤ Tao < 0℃, the initial opening degree of the electronic expansion valve is 180 steps; if 0 ≤ Tao < 15℃, the initial opening degree of the electronic expansion valve is 280 steps; and if Tao ≥ 15℃, the initial opening degree of the electronic expansion valve is 360 steps.

[0063] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A method for controlling the target exhaust temperature in a heating mode, characterized in that, When the unit starts for heating, the startup steps include: Step 1): The electronic expansion valve resets and opens to its initial opening degree, and the water pump is turned on simultaneously, continuously monitoring the return water temperature and the flow switch; Step 2): After the flow switch is continuously closed for 30 seconds, the outdoor fan is turned on; Step 3): The compressor is turned on after 10 seconds. After the compressor starts and the electronic expansion valve maintains its initial opening degree for 3 minutes, the startup control stage begins; the startup control stage has Δt = 2, and the startup control stage includes the following steps: When Tao ≤ 0℃: If Tin n If the temperature is ≤40℃, the target exhaust temperature calculation formula shall be executed according to Tpo1; If Tin n For temperatures >40℃, select Tpo1 or Tpo2 based on the different condensation temperatures: if Pdt ≥ Tout n The target exhaust temperature calculation formula is executed according to Tpo2. If Pdt < Tout n Then the target exhaust temperature calculation formula shall be executed according to Tpo1; When Tao > 0℃, the target exhaust temperature calculation formula shall be executed according to Tpo1; When the startup control phase running time t≥15min or Pdt-Tout n If the temperature exceeds 5℃, the system will enter the operation control phase. The target exhaust temperature during the operation control phase is set according to Tpo2, and Δt is adjustable. The initial value of Δt is 2, and the process includes the following steps: After entering the operation control phase, the return water temperature during the operation control phase is recorded at 5-minute intervals. Tin, when Tin n At ≤45℃: If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt+1 until Δt = 5 and no longer increases; If 12.5% ​​≤ (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 15%, then control Δt to maintain the current parameter. If (Tin) n -Tin n-1 ) / Tin n-1 If ≤15%, then control Δt-1 until Δt=2 no longer decreases when Tin n When the temperature is >45℃: If (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 10%, then control Δt+1 until Δt = 5 and no longer increases; If 10% ≤ (Tin) n -Tin n-1 ) / Tin n-1 If the value is less than 12.5%, then control Δt to maintain the current parameter. If (Tin) n -Tin n-1 ) / Tin n-1 If the value is ≤12.5%, then control Δt-1 until Δt=2 no longer decreases; The definitions are as follows: Pd is the high-pressure side pressure, Pdt is the condensation temperature converted from the high-pressure side pressure, and Tin... n Tin is the current return water temperature. n-1 Tout is the temperature of the previous return water. n The current outlet water temperature is given by Tpo1, where Tao is the ambient temperature, and Δt is the outlet water temperature correction factor. The target exhaust temperature is calculated using the formulas Tpo1 and Tpo2: Tpo1 = A * compressor frequency + B + C * Pdt - D * Tao + E, Tpo2 = A * compressor frequency + B + C * (Tout) * Pdt - D * Tao + E. n +Δt)-D*Tao+E, where A, B, C, D, and E are coefficients, with A in ℃ / Hz and B and E in ℃.

2. The method for controlling the target exhaust temperature in heating mode according to claim 1, characterized in that, A, B, C, D, and E are adjustable coefficients. Adjustable coefficient A includes A1-A5, B includes B1-B5, C includes C1-C5, D includes D1-D5, and E includes E1-E5. Their specific values ​​are adjusted according to the table below: Adjustable coefficients A and B are selected according to the current compressor frequency range (e.g., when the compressor frequency is 50Hz, select A2 and B2); adjustable coefficients C, D, and E are selected according to the current ambient temperature (Tao) range (e.g., when Tao=0℃, select C3, D3, and E3); after selecting a single coefficient value, it is substituted into the target exhaust temperature calculation formula (Tpo1 or Tpo2) of claim 1.

3. The method for controlling the target exhaust temperature in heating mode according to claim 1, characterized in that, The initial opening degree of the electronic expansion valve is adjusted according to the ambient temperature. If Tao < -15℃, the initial opening degree of the electronic expansion valve is 140 steps; if -15 ≤ Tao < 0℃, the initial opening degree of the electronic expansion valve is 180 steps; if 0 ≤ Tao < 15℃, the initial opening degree of the electronic expansion valve is 280 steps; and if Tao ≥ 15℃, the initial opening degree of the electronic expansion valve is 360 steps.

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