A control method for an adaptive secondary water-exchange water tank of a heat pump system

Abstract

A control method for an adaptive secondary water exchange tank of a heat pump system, comprising a heat pump and a water exchange tank, wherein the heat pump is connected to a heat exchange coil arranged in the water exchange tank through an inlet and outlet water pipe, and the water pump is connected in series between the inlet and outlet water pipes of the heat pump, and the operation comprises the following steps: step one, power on and run, and enter step two; step two, the heat pump is operated for heating, and enter step three; step three, after the heat pump runs the platform frequency, it is unloaded to the lowest frequency F1 and enters step four; step four, the central controller of the heat pump determines whether Tout-Tint≤8℃ is established, and when it is established, enters step five, otherwise enters step fourteen, wherein Tout is the water temperature of the outlet pipe of the heat pump. The present invention combines the condensing temperature of the heat pump, the inlet and outlet water temperature difference and the water temperature rise rate in the water exchange tank to adjust the state of the heat pump, so that it can adaptively adapt to water exchange tanks of different capacities and can operate efficiently.

Description

Technical Field

[0001] The invention relates to a heat pump system, in particular to a control method for a self-adaptive secondary water-exchange water tank of the heat pump system. Background Art

[0002] In the market, when a heat pump is used in conjunction with a water exchange tank, heat exchange is generally performed between water and water, that is, the inlet and outlet water pipes of the heat pump are connected to the heat exchange coil in the water exchange tank to perform heat exchange with the water in the water exchange tank.

[0003] For example, Chinese patent document No. CN 104034031A disclosed on September 10, 2014, a heat pump water heater, comprising a compressor, a condenser and an evaporator connected in sequence; a water tank having a water outlet and a water inlet; a water pump connected between the water outlet of the water tank and the hot water outlet pipe; a first valve connected between the cold water inlet pipe and the water side inlet of the condenser; a second valve connected between the water inlet of the water tank and the network circulating water pipe; a third valve, one end of which is connected between the first valve and the water side inlet of the condenser, and the other end is connected to the hot water outlet pipe downstream of the water pump; the water side outlet of the condenser is connected to the water inlet of the water tank through a water pipe. This type of heat pump water heater can only adapt to a water tank of a single specification, while the water exchange tanks on the market have various specifications. When the volume of the water exchange tank is small, the size of the heat exchange coil is short, and the heat pump load is too large, it is easy to cause insufficient heat exchange, resulting in performance deviation of the whole machine or failure, etc.; or, when the volume of the water exchange tank is too large and the heat pump load is too small, it causes the temperature to rise too slowly, which makes users dissatisfied, so it needs to be improved. Summary of the invention

[0004] The object of the present invention is to provide a control method for an adaptive secondary water-exchange water tank of a heat pump system with a wide range of applications, so as to overcome the deficiencies in the prior art.

[0005] A control method for an adaptive secondary water exchange tank of a heat pump system designed for this purpose comprises a heat pump and a water exchange tank, wherein the heat pump is connected to a heat exchange coil arranged in the water exchange tank through an inlet and outlet water pipe, and a water pump is connected in series between the inlet and outlet water pipes of the heat pump, and the operation comprises the following steps:

[0006] Step 1: Power on and run, then go to step 2;

[0007] Step 2: Heat pump heating operation, proceed to step 3;

[0008] Step 3: After the heat pump runs at the platform frequency, it is unloaded to the lowest frequency F1 and then goes to step 4;

[0009] Step 4: The central controller of the heat pump determines whether Tout-Tint≤8°C is established. If it is established, it proceeds to step 5, otherwise it proceeds to step 14, where Tout is the water temperature of the heat pump outlet pipe and Tint is the water temperature of the heat pump inlet pipe;

[0010] Step 5: The central controller determines whether ΔTW<ΔTWset is established. If it is established, the process goes to step 6, otherwise it goes to step 10, wherein ΔTW is the actual temperature rise rate of the water temperature in the water exchange tank within the set time TM, ΔTWset is the set temperature rise rate of the water temperature in the water exchange tank within the set time TM, the value range of TM is 0 to 10 minutes, and the value range of ΔTWset is 0 to 20°C / minute;

[0011] Step 6: The central controller determines whether TK≤TKset is established. If it is established, the process goes to step 7, otherwise it goes to step 15, wherein TK is the temperature comparison difference, TK=TR-TW, TR is the condensing temperature of the heat pump, TW is the current water temperature of the heat exchange water tank, Tkset is the temperature setting difference, and the value range of Tkset is 0-100°C;

[0012] Step 7: Control the compressor of the heat pump through the central controller to increase the frequency by one gear at every TM*4 intervals. When it is triggered for the first time, the frequency is increased immediately, and the process goes to step 8;

[0013] Step 8: When the central controller determines that any one of Tout-Tint>8℃, ΔTW≥ΔTWset or TK>Tkset is established, go to step 3; otherwise, go to step 16;

[0014] Step nine, continue running and go to step ten;

[0015] Step 10, judging whether TK>Tkset is established through the central controller, if it is established, proceeding to step 11, otherwise proceeding to step 9;

[0016] Step 11, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*3 intervals, and reduce the frequency immediately when it is triggered for the first time, and enter step 13;

[0017] Step 12, continue running and enter step 11;

[0018] Step 13: When the central controller determines that either ΔTW≥ΔTWset or TK≤Tkset is satisfied, proceed to step 3; otherwise, proceed to step 12;

[0019] Step 14: the central controller controls the water pump to output fully, and then proceeds to step 17;

[0020] Step 15, continue running and enter step 6;

[0021] Step 16, continue running and enter step 7;

[0022] Step 17, judging by the central controller whether Tout-Tint>8℃ is established, if it is established, proceeding to step 18, otherwise proceeding to step 4;

[0023] Step 18, judging through the central controller whether TK>TKset+10°C is established, if it is established, proceeding to step 19, otherwise proceeding to step 22;

[0024] Step 19, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at each TM interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 20;

[0025] Step 20, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 21;

[0026] Step 21, continue running and enter step 19;

[0027] Step 22, judging by the central controller whether ΔTW≥ΔTWset and TK>TKset are established, if it is established, proceeding to step 23, otherwise proceeding to step 26;

[0028] Step 23, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*2 interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 24;

[0029] Step 24: When the central controller determines that any one of Tout-Tint≤8°C, ΔTW<ΔTWset or TK≤Tkset is established, proceed to step 3; otherwise, proceed to step 25;

[0030] Step 25, continue running and enter step 23;

[0031] Step 26, controlling the compressor of the heat pump to maintain the current operating frequency through the central controller, and proceeding to step 27;

[0032] Step 27, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 28;

[0033] Step 28, continue running and enter step 26.

[0034] The present invention adjusts the state of the heat pump by combining the condensing temperature of the heat pump, the inlet and outlet water temperature difference and the water temperature rise rate in the heat exchange water tank, so that it can adaptively adapt to heat exchange water tanks of different capacities and operate efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of an embodiment of the present invention.

[0036] Figure 2 This is one of the operation flow charts of the present invention.

[0037] Figure 3 This is the second operation flow chart of the present invention.

[0038] In the figure, 1 is a heat pump, 2 is a heat exchange water tank, and 3 is a heat exchange coil. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] See also Figure 1-Figure 3 A control method for an adaptive secondary water exchange tank of a heat pump system includes a heat pump 1 and a water exchange tank 2. The heat pump 1 is connected to a heat exchange coil 3 arranged in the water exchange tank 2 through an inlet and outlet water pipe. A water pump 4 is connected in series between the inlet and outlet water pipes of the heat pump 1. The operation includes the following steps:

[0041] Step 1: Power on and run, then go to step 2;

[0042] Step 2: Heat pump heating operation, proceed to step 3;

[0043] Step 3: After the heat pump runs at the platform frequency, it is unloaded to the lowest frequency F1 and goes to step 4.

[0044] In this embodiment, step three is a conventional step for heating operation, and frequency F1 is the lowest frequency when the compressor is running stably during heating, which is usually preset by the manufacturer.

[0045] Step 4: The central controller of the heat pump determines whether Tout-Tint≤8°C is established. If it is established, it proceeds to step 5, otherwise it proceeds to step 14, where Tout is the water temperature of the heat pump outlet pipe and Tint is the water temperature of the heat pump inlet pipe;

[0046] Step five, determine through the central controller whether ΔTW<ΔTWset is established. If it is established, go to step six, otherwise go to step ten, where ΔTW is the actual heating rate of the water temperature in the heat exchange water tank within the set time TM, ΔTWset is the set heating rate of the water temperature in the heat exchange water tank within the set time TM, the value range of TM is 0 to 10 minutes, and the value range of ΔTWset is 0 to 20℃ / minute.

[0047] In this embodiment, when ΔTW<ΔTWset holds, it is determined that the current hot water demand of the water exchange tank is not met, and the next step of determination is required.

[0048] Step six, determine whether TK≤TKset is established through the central controller. When it is established, go to step seven, otherwise go to step fifteen, where TK is the temperature comparison difference, TK=TR-TW, TR is the condensing temperature of the heat pump, TW is the current water temperature of the water exchange water tank, Tkset is the temperature setting difference, and the value range of Tkset is 0~100℃.

[0049] In this embodiment, the condensing temperature of the heat pump is calculated by converting the detection value of the heat pump pressure sensor.

[0050] Step 7: Control the compressor of the heat pump through the central controller to increase the frequency by one gear at every TM*4 intervals. When it is triggered for the first time, the frequency is increased immediately, and the process goes to step 8;

[0051] Step 8: When the central controller determines that any one of Tout-Tint>8℃, ΔTW≥ΔTWset or TK>Tkset is established, go to step 3; otherwise, go to step 16;

[0052] Step nine, continue running and go to step ten;

[0053] Step 10, judging whether TK>Tkset is established through the central controller, if it is established, proceeding to step 11, otherwise proceeding to step 9;

[0054] Step 11, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*3 intervals, and reduce the frequency immediately when it is triggered for the first time, and enter step 13;

[0055] Step 12, continue running and enter step 11;

[0056] Step 13: When the central controller determines that either ΔTW≥ΔTWset or TK≤Tkset is satisfied, proceed to step 3; otherwise, proceed to step 12;

[0057] Step 14: the central controller controls the water pump to output fully, and then proceeds to step 17;

[0058] Step 15, continue running and enter step 6;

[0059] Step 16, continue running and enter step 7;

[0060] Step 17, judging by the central controller whether Tout-Tint>8℃ is established, if it is established, proceeding to step 18, otherwise proceeding to step 4;

[0061] Step 18, judging through the central controller whether TK>TKset+10°C is established, if it is established, proceeding to step 19, otherwise proceeding to step 22;

[0062] Step 19, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at each TM interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 20;

[0063] Step 20, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 21;

[0064] Step 21, continue running and enter step 19;

[0065] Step 22: The central controller determines whether ΔTW≥ΔTWset and TK>TKset are established. If so, proceed to step 23; otherwise, proceed to step 26.

[0066] In this embodiment, when ΔTW≥ΔTWset and TK>TKset is established, it is judged that the current operating frequency of the heat pump compressor is too high, or the water tank volume is too small, and the operating frequency of the compressor needs to be reduced to ensure that the heat pump system can operate efficiently.

[0067] Step 23, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*2 interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 24;

[0068] Step 24: When the central controller determines that any one of Tout-Tint≤8°C, ΔTW<ΔTWset or TK≤Tkset is established, proceed to step 3; otherwise, proceed to step 25;

[0069] Step 25, continue running and enter step 23;

[0070] Step 26, controlling the compressor of the heat pump to maintain the current operating frequency through the central controller, and proceeding to step 27;

[0071] Step 27, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 28;

[0072] Step 28, continue running and enter step 26.

[0073] Application Examples

[0074] When the heat pump receives a start-up command, after the heat pump starts and runs at the preset platform frequency, the heat pump is unloaded to the preset minimum operating frequency F1 for operation, and the water pump is adjusted similar to a fixed flow rate according to the target flow rate.

[0075] When the heat pump runs stably at the lowest operating frequency F1 for 5 minutes, it enters different adjustments according to the inlet and outlet water temperature difference of the water exchange water tank connected to the heat pump.

[0076] At this time, the preset TM is 5 minutes, ΔTWset is 0.5°C / minute, and Tkset is 5°C.

[0077] 1. When the heat pump central controller collects and determines that Tout-Tint≤8℃, the central controller detects the actual heating rate ΔTW of the water tank temperature every 5 minutes.

[0078] When the central controller determines that ΔTW<ΔTWset=0.5℃ / minute, it is considered that the current heating demand of the heat pump is insufficient. When the central controller further determines that TK≤Tkset=5℃, it is considered that the heat exchange between the heat pump and the water exchange tank is good. Since TM*4=5min*4=20min, the central controller controls the compressor of the heat pump to increase the frequency by one level every 20 minutes, and increases the frequency immediately when it is triggered for the first time.

[0079] Next, continue to run until the central controller determines that ΔTW≥ΔTWset=0.5℃ / minute, or Tout-Tint>8℃ or TK>Tkset=5℃, exits the current frequency increase logic, and then the heat pump is unloaded to the lowest operating frequency F1 for operation, that is, returns to step three.

[0080] When the central controller determines that ΔTW≥ΔTWset=0.5℃ / minute, the current heating demand of the heat pump is considered to be met, and it is necessary to further determine whether the heat pump is in the best operating state. When the central controller determines that TK>Tkset=5℃, it indicates that the heat exchange between the current heat exchange water tank and the heat pump is not in the best state, and it is judged that the current heating capacity of the heat pump is excessive. The heat pump needs to be reduced by one gear every 15 minutes, and the frequency should be reduced immediately when it is triggered for the first time. TM*3=5 minutes*3=15 minutes.

[0081] Next, the operation continues until the central controller determines that TK≤Tkset=5°C or ΔTWset<ΔTW is established, then the current frequency reduction logic is exited and the process returns to step three.

[0082] 2. When the heat pump central controller collects and determines that Tout-Tint>8℃, the central controller controls the water pump to run at 100% full output. Then, the central controller detects the actual heating rate ΔTW of the water temperature in the heat exchange water tank every 5 minutes.

[0083] When the central controller determines that TK>Tkset+10℃=5℃+10℃=15℃, it is judged that the current heat exchange between the water exchange tank and the heat pump is seriously poor. If the current operation is continued, the heat pump may fail.

[0084] Therefore, the central controller reduces the operating frequency of the heat pump compressor by one level every 5 minutes, and reduces the frequency immediately when it is triggered for the first time until TK≤Tkset=5℃ is established, exits the current frequency reduction logic, and returns to step three.

[0085] When the central controller determines that TK>Tkset+10℃=5℃+10℃=15℃ is not established, and ΔTW≥ΔTWset=0.5℃ / minute and TK>Tkset=5℃ are satisfied at the same time, it is considered that the current heating capacity of the heat pump is excessive, and the compressor operating frequency of the heat pump is reduced by one gear every 10 minutes, and the frequency is reduced immediately when it is triggered for the first time, until any one of ΔTW<ΔTWset=0.5℃ / minute, or TK≤Tkset=5℃, or Tout-Tint≤8℃ is satisfied, the current frequency reduction logic is exited and the process returns to step 3. Among them, TM*2=5min*2=10min.

[0086] When the central controller determines that ΔTW≥ΔTWset=0.5℃ / minute and TK>5℃ are not true, it indicates that the current heating demand of the heat pump is insufficient and the condensing temperature of the heat pump is 5℃ higher than the water temperature in the water exchange tank, which means that the heat exchange between the water exchange tank and the heat pump is not good. At this time, for the safety of the heat pump system, the compressor of the heat pump is kept running at the current frequency until TK≤5℃, then the logic is exited and returned to step three.

[0087] In this embodiment, if the process proceeds from step 4 to step 5 and step 6, and then gets stuck at step 6 and cannot proceed to step 7, if the current actual operating time reaches 0.5 to 3 hours, an alarm should be given to indicate that the heating capacity of the heat pump does not meet the standard and the heat pump needs to be replaced.

[0088] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0089] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A control method for an adaptive secondary water exchange tank of a heat pump system, comprising a heat pump (1) and a water exchange tank (2), characterized in that The heat pump (1) is connected to the heat exchange coil (3) arranged in the water exchange water tank (2) through the inlet and outlet water pipes, and the water pump (4) is connected in series between the inlet and outlet water pipes of the heat pump (1). The operation includes the following steps: Step 1: Power on and run, then go to step 2; Step 2: Heat pump heating operation, proceed to step 3; Step 3: After the heat pump runs at the platform frequency, it is unloaded to the lowest frequency F1 and then goes to step 4; Step 4: The central controller of the heat pump determines whether Tout-Tint≤8°C is established. If it is established, it proceeds to step 5, otherwise it proceeds to step 14, where Tout is the water temperature of the heat pump outlet pipe and Tint is the water temperature of the heat pump inlet pipe; Step 5: The central controller determines whether ΔTW<ΔTWset is established. If it is established, the process goes to step 6, otherwise it goes to step 10, wherein ΔTW is the actual temperature rise rate of the water temperature in the water exchange tank within the set time TM, ΔTWset is the set temperature rise rate of the water temperature in the water exchange tank within the set time TM, the value range of TM is 0 to 10 minutes, and the value range of ΔTWset is 0 to 20°C / minute; Step 6: The central controller determines whether TK≤TKset is established. If it is established, the process goes to step 7, otherwise it goes to step 15, wherein TK is the temperature comparison difference, TK=TR-TW, TR is the condensing temperature of the heat pump, TW is the current water temperature of the heat exchange water tank, Tkset is the temperature setting difference, and the value range of Tkset is 0-100°C; Step 7: Control the compressor of the heat pump through the central controller to increase the frequency by one gear at every TM*4 intervals. When it is triggered for the first time, the frequency is increased immediately, and the process goes to step 8; Step 8: When the central controller determines that any one of Tout-Tint>8℃, ΔTW≥ΔTWset or TK>Tkset is established, go to step 3; otherwise, go to step 16; Step nine, continue running and go to step ten; Step 10, judging whether TK>Tkset is established through the central controller, if it is established, proceeding to step 11, otherwise proceeding to step 9; Step 11, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*3 intervals, and reduce the frequency immediately when it is triggered for the first time, and enter step 13; Step 12, continue running and enter step 11; Step 13: When the central controller determines that either ΔTW≥ΔTWset or TK≤Tkset is satisfied, proceed to step 3; otherwise, proceed to step 12; Step 14: the central controller controls the water pump to output fully, and then proceeds to step 17; Step 15, continue running and enter step 6; Step 16, continue running and enter step 7; Step 17, judging by the central controller whether Tout-Tint>8℃ is established, if it is established, proceeding to step 18, otherwise proceeding to step 4; Step 18, judging through the central controller whether TK>TKset+10°C is established, if it is established, proceeding to step 19, otherwise proceeding to step 22; Step 19, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at each TM interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 20; Step 20, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 21; Step 21, continue running and enter step 19; Step 22, judging by the central controller whether ΔTW≥ΔTWset and TK>TKset are established, if it is established, proceeding to step 23, otherwise proceeding to step 26; Step 23, control the compressor of the heat pump through the central controller to reduce the frequency by one gear at every TM*2 interval, and reduce the frequency immediately when it is triggered for the first time, and enter step 24; Step 24: When the central controller determines that any one of Tout-Tint≤8°C, ΔTW<ΔTWset or TK≤Tkset is established, proceed to step 3; otherwise, proceed to step 25; Step 25, continue running and enter step 23; Step 26, controlling the compressor of the heat pump to maintain the current operating frequency through the central controller, and proceeding to step 27; Step 27, judging whether TK≤Tkset is established by the central controller, if it is established, proceeding to step 3, otherwise proceeding to step 28; Step 28, continue running and enter step 26.

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