A hot air machine control method for improving heating capacity under easy frosting conditions

Abstract

The application discloses a hot air machine control method for improving heating capacity under easy frosting conditions, when the hot air machine starts to heat, an electronic expansion valve is controlled according to an outdoor environment temperature Tao to open to a target step number at an initial opening degree, and whether it is an easy frosting condition is determined in a t1-t3 period after starting, if it is the easy frosting condition, the electronic expansion valve is controlled according to an easy frosting opening degree of the easy frosting condition, and if it is not the easy frosting condition, the electronic expansion valve is controlled according to a non-easy frosting opening degree. The application can solve the problem of poor heating effect when the unit is easy to frost under high outdoor humidity, under the premise of ensuring the reliability of the compressor, the appropriate exhaust gas superheat degree is controlled to be lower than the normal target exhaust gas superheat degree, thereby solving the problems of fast frosting of the outdoor unit and poor heating effect, and when the unit is not easy to frost under low outdoor humidity, the electronic expansion valve is controlled according to the normal gas return superheat degree, thereby ensuring the reliability of the compressor and the capacity of the unit.

Description

Technical Field

[0001] This invention relates to a control method for hot air blowers that improves heating capacity under conditions prone to frosting. Background Technology

[0002] Compared to traditional water-cooled heat pumps, air source heat pumps are widely used in the northern market due to their simple installation. Since the northern region has low temperatures and high heating requirements, they generally use flash tanks with gas-injection enthalpy-increasing compressors to increase the heating capacity at low temperatures and meet the heating requirements in winter.

[0003] Under normal circumstances, when the outdoor temperature is between 7 and -7℃, the outdoor air humidity may be relatively high. When the temperature of the outdoor unit's evaporator is lower than the air dew point temperature, the outdoor unit will frost. Currently, the control of the electronic expansion valve is only to ensure the reliability of the compressor and does not fully consider the heating effect. At this time, the electronic expansion valve will close slightly. After the electronic expansion valve closes slightly, the temperature of the outdoor unit's heat exchanger becomes lower, and the frost on the outdoor unit's evaporator will accelerate. As the frost accelerates, the heating capacity will further decrease. The electronic expansion valve will continue to close slightly, and frost will form again, resulting in even less heating capacity. This leads to poor heating performance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a hot air blower control method for improving heating capacity under conditions prone to frosting, effectively solving the problems mentioned in the background art.

[0005] The technical solution adopted in this invention is:

[0006] A method for controlling a hot air blower to improve its heating capacity under conditions prone to frosting is provided. When the hot air blower starts to heat, the electronic expansion valve is controlled to open to the target number of steps according to the outdoor ambient temperature Tao. During the time period t1-t3 after startup, it is determined whether the operating condition is prone to frosting. If it is prone to frosting, the electronic expansion valve is controlled to the frosting opening degree. If it is not prone to frosting, the electronic expansion valve is controlled to the non-frosting opening degree.

[0007] Preferably, the determination of whether a condition is prone to frosting includes the following steps:

[0008] Step 1) Collect outdoor ambient temperature Tao, condenser temperature Tdef, indoor coil temperature Te, and indoor temperature Tai. Set △T1 = Te - Tai, △T2 = Tao - Tdef, define △T1 at t1 as the current maximum value △T1max, and △T2 at t1 as the current minimum value △T2min, and store them in the controller.

[0009] Step 2) Update ΔT1max and ΔT2min in the controller during the time period t1-t2, where t1<t2<t3: When ΔT1>ΔT1max is detected, the current ΔT1 is re-stored in the controller to update the ΔT1max value; when ΔT1≤ΔT1max is detected, the previously stored ΔTmax value in the controller remains unchanged; when ΔT2<ΔT2min is detected, the current ΔT2 is re-stored in the controller to update the ΔT2min value; when ΔT2≥ΔT2min is detected, the previously stored ΔT2min value in the controller remains unchanged.

[0010] Step 3) During the time period t2-t3, the following judgment is made: when △T1max-△T1>a or △T2-△T2min>b, the current working condition is determined to be a condition prone to frosting; otherwise, it is a condition not prone to frosting.

[0011] Preferably, in step 1), when collecting outdoor ambient temperature Tao, condenser temperature Tdef, inner coil temperature Te, and indoor temperature Tai, the collection method is as follows: collect once per second, take the average value after 30 seconds, and complete the data statistics every 30 seconds.

[0012] Preferably, t1 is 5 minutes, t2 is 10 minutes, t3 is 30 minutes, a is 0.2℃, and b is 0.3℃.

[0013] Preferably, the frosting-prone opening control includes the following steps:

[0014] Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te;

[0015] Step 2) Define Tdsh1 as the target exhaust superheat for easy frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat for easy frosting Tdsh1: If Tdsh-Tdsh1>0, control the electronic expansion valve to open by a larger number of steps; if Tdsh-Tdsh1<0, control the electronic expansion valve to close by a smaller number of steps; if Tdsh-Tdsh1=0, control the electronic valve to keep its opening unchanged.

[0016] Preferably, the anti-frost opening control includes the following steps:

[0017] Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te;

[0018] Step 2) Define Tdsh2 as the target exhaust superheat that is not prone to frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat Tdsh2 that is not prone to frosting: if Tdsh-Tdsh2>0, control the electronic expansion valve to open more steps; if Tdsh-Tdsh2<0, control the electronic expansion valve to close less steps; if Tdsh-Tdsh2=0, control the electronic valve to keep its opening unchanged.

[0019] This invention can solve the problem of poor heating performance when the unit is prone to frosting in high outdoor humidity. Under the premise of ensuring the reliability of the compressor, it controls the appropriate exhaust superheat to be lower than the normal target exhaust superheat, thereby solving the problem of rapid frosting and poor heating performance of the outdoor unit. When the outdoor humidity is low and the unit is not prone to frosting, the electronic expansion valve controls the return gas superheat according to the normal return gas superheat, which ensures both the reliability of the compressor and the capacity of the unit. Detailed Implementation

[0020] The present invention will be further described in detail below through specific embodiments.

[0021] A method for controlling a hot air blower to improve its heating capacity under conditions prone to frosting is provided. When the hot air blower starts to heat, the electronic expansion valve is controlled to open to the target number of steps according to the outdoor ambient temperature. Within 5-30 minutes after startup, it is determined whether the operating condition is prone to frosting. If it is, the electronic expansion valve is controlled to open at the frosting opening degree. If it is not, the electronic expansion valve is controlled to open at the non-frosting opening degree.

[0022] The determination of whether a condition is prone to frosting includes the following steps:

[0023] Step 1) Collect outdoor ambient temperature Tao, condenser temperature Tdef, indoor coil temperature Te, and indoor temperature Tai. The collection method is as follows: collect once per second, take the average value after 30 seconds, and complete the data statistics every 30 seconds. Set △T1 = Te - Tai, △T2 = Tao - Tdef, define △T1 at 5 minutes as the current maximum value △T1max, and △T2 at 5 minutes as the current minimum value △T2min, and store them in the controller.

[0024] Step 2) Update △T1max and △T2min in the controller within 5-10 minutes: When △T1>△T1max is detected, the current △T1 is re-stored in the controller to update the △T1max value; when △T1≤△T1max is detected, the previously stored △Tmax value in the controller remains unchanged; when △T2<△T2min is detected, the current △T2 is re-stored in the controller to update the △T2min value; when △T2≥△T2min is detected, the previously stored △T2min value in the controller remains unchanged.

[0025] Step 3) Within 10-30 minutes, make the following judgment: when △T1max-△T1>0.2℃ or △T2-△T2min>0.3℃, the current working condition is determined to be a condition prone to frosting; otherwise, it is a condition not prone to frosting.

[0026] The aforementioned frosting-prone opening control includes the following steps:

[0027] Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te;

[0028] Step 2) Define Tdsh1 as the target exhaust superheat for easy frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat Tdsh1 for easy frosting: If Tdsh-Tdsh1>0, control the electronic expansion valve to open by more steps; if Tdsh-Tdsh1<0, control the electronic expansion valve to close by more steps; if Tdsh-Tdsh1=0, control the electronic valve to keep its opening unchanged. The adjustment steps of the electronic expansion valve = k(Tdsh-Tdsh1), where k is the proportional adjustment coefficient, which is preset in the system.

[0029] The aforementioned anti-frost opening control includes the following steps:

[0030] Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te;

[0031] Step 2) Define Tdsh2 as the target exhaust superheat that is not prone to frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat Tdsh2: If Tdsh-Tdsh2>0, control the electronic expansion valve to open by a larger step; if Tdsh-Tdsh2<0, control the electronic expansion valve to close by a smaller step; if Tdsh-Tdsh2=0, control the electronic valve to keep its opening unchanged. The adjustment step of the electronic expansion valve = k(Tdsh-Tdsh2), where k is the proportional adjustment coefficient, which is preset in the system.

[0032] When the hot air blower is started, the initial opening of the electronic expansion valve shall be performed according to the following table:

[0033] Outdoor ambient temperature Tao Electronic expansion valve steps pls Tao≥7℃ 180 2≤Tao<7℃ 165 -3≤Tao<2℃ 150 -7≤Tao<-3℃ 135 Tao < -7℃ 120

[0034] The target exhaust superheat Tdsh1 for easy frosting is determined according to the inner coil temperature Te and condenser temperature Tdef in the table below, with intermediate data linearly fitted:

[0035]

[0036] The target exhaust superheat Tdsh2, which is less prone to frosting, is determined according to the inner coil temperature Te and condenser temperature Tdef in the table below, with intermediate data subjected to linear fitting:

[0037]

[0038] Taking a 40-type hot air blower with outdoor operating conditions of 20 / 15°C and indoor operating conditions of 2 / 1°C as an example, the data comparison before and after the optimization of the electronic expansion valve control is as follows:

[0039] Before electronic expansion valve control optimization:

[0040]

[0041] After optimization of electronic expansion valve control:

[0042]

[0043] The test data shows that the optimized heating capacity increased by 733W and the energy efficiency increased by 0.68.

[0044] 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 a hot air blower to improve its heating capacity under conditions prone to frosting, characterized in that, When the hot air blower starts to heat, the electronic expansion valve is controlled to open to the target number of steps according to the outdoor ambient temperature Tao. During the time period t1-t3 after startup, it is determined whether the operating condition is prone to frosting. If it is, the electronic expansion valve is controlled according to the frosting condition opening degree; otherwise, it is controlled according to the non-frosting condition opening degree. The determination of whether the operating condition is prone to frosting includes the following steps: Step 1) Collect outdoor ambient temperature Tao, condenser temperature Tdef, indoor coil temperature Te, and indoor temperature Tai. Set △T1 = Te - Tai, △T2 = Tao - Tdef, define △T1 at t1 as the current maximum value △T1max, and △T2 at t1 as the current minimum value △T2min, and store them in the controller. Step 2) Update △T1max and △T2min in the controller during the time period t1-t2, where t1<t2<t3: When △T1>△T1max is detected, the current △T1 is re-stored in the controller to update the △T1max value; when △T1≤△T1max is detected, the △Tmax value stored in the controller remains unchanged. When △T2<△T2min is detected, the current △T2 is re-stored in the controller to update the △T2min value; when △T2≥△T2min is detected, the △T2min value stored in the controller remains unchanged. Step 3) Make the following judgment during the time period t2-t3: When △T1max-△T1>a or △T2-△T2min>b, the current operating condition is determined to be an easy-to-frost operating condition; otherwise, it is an easy-to-frost operating condition.

2. The method for controlling a hot air blower to improve heating capacity under conditions prone to frosting, as described in claim 1, is characterized in that... In step 1), when collecting outdoor ambient temperature Tao, condenser temperature Tdef, inner coil temperature Te, and indoor temperature Tai, the collection method is as follows: collect once per second, take the average value after 30 seconds, and complete the data statistics every 30 seconds.

3. The method for controlling a hot air blower to improve heating capacity under conditions prone to frosting, as described in claim 1, is characterized in that... The values ​​t1, t2, t3, t3, a, and b are given. t1 is 5 minutes, t2 is 10 minutes, t3 is 30 minutes, a is 0.2℃, and b is 0.3℃.

4. The method for controlling a hot air blower to improve heating capacity under conditions prone to frosting, as described in claim 1, is characterized in that... The aforementioned frosting-prone opening control includes the following steps: Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te; Step 2) Define Tdsh1 as the target exhaust superheat for easy frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat for easy frosting Tdsh1: If Tdsh-Tdsh1>0, control the electronic expansion valve to open by a larger number of steps; if Tdsh-Tdsh1<0, control the electronic expansion valve to close by a smaller number of steps; if Tdsh-Tdsh1=0, control the electronic valve to keep its opening unchanged.

5. A method for controlling a hot air blower to improve heating capacity under conditions prone to frosting, as described in claim 1, characterized in that, The aforementioned anti-frost opening control includes the following steps: Step 1) Collect the internal coil temperature Te and the compressor discharge temperature Tda. The current discharge superheat Tdsh = Tda - Te; Step 2) Define Tdsh2 as the target exhaust superheat that is not prone to frosting. Compare the current exhaust superheat Tdsh with the target exhaust superheat Tdsh2 that is not prone to frosting: if Tdsh-Tdsh2>0, control the electronic expansion valve to open more steps; if Tdsh-Tdsh2<0, control the electronic expansion valve to close less steps; if Tdsh-Tdsh2=0, control the electronic valve to keep its opening unchanged.

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