Method for detecting inlet water temperature sensor and outlet water temperature sensor in heat pump system

Abstract

The invention relates to the technical field of temperature sensor detection, in particular to a water inlet and outlet temperature sensor detection method in a heat pump system, which comprises the following steps: firstly, judging the running state of a compressor, and if the running state is a running mode, judging the cold and warm running mode of a unit; if the mode is the heating mode or the refrigerating mode, the difference value between the water inlet temperature and the water outlet temperature and the coil pipe temperature and the environment temperature are compared, so that whether the water inlet temperature sensor or the water outlet temperature sensor deviates or fails or not is judged; if the operation mode is the non-operation mode, the difference value between the water inlet temperature and the water outlet temperature is compared so as to judge whether the water inlet temperature sensor or the water outlet temperature sensor deviates or fails or not. According to the method for detecting the water inlet temperature sensor and the water outlet temperature sensor in the heat pump system, a more accurate and reliable sensor state judgment scheme can be provided under the condition that temperature changes are affected by various factors.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature sensor detection, and more specifically, to a method for detecting water inlet and water outlet temperature sensors in a heat pump system. Background Art

[0002] In the heat pump system, the water inlet temperature sensor and the water outlet temperature sensor are important components for controlling the operation of the system. Their data are directly used to determine the operating status of the heat pump, control the start and stop of the compressor, and perform key functions such as antifreeze protection. However, over time, the sensors may be affected by long-term use, environmental interference, or software and hardware failures, causing temperature offset, drift, or failure. These problems may cause the system to be unable to be accurately controlled, which in turn affects the normal operation of the heat pump and may even cause damage to the equipment.

[0003] Existing temperature sensor detection technology mainly focuses on the detection of short-circuit and open-circuit faults of sensors. In this type of technology, the circuit state of the sensor is usually detected to determine whether it has failed. When the sensor is short-circuited or open-circuited, the system can alarm or protect by comparing whether the voltage or current output of the temperature signal exceeds the normal range. Although this method can effectively identify extreme faults of the sensor, it cannot solve the problem of temperature offset of the sensor - that is, the temperature value output by the sensor deviates from the true value, but it is not completely invalid. The offset problem of the sensor is usually caused by aging after long-term use, environmental interference, installation errors, etc. Although these problems will not cause the sensor to fail completely, they will significantly affect the accuracy of the temperature data, thereby affecting the performance and operating efficiency of the temperature control system. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiency that the prior art cannot detect whether the water inlet temperature sensor and the water outlet temperature sensor are offset in a heat pump system, and to provide a method for detecting the water inlet and water outlet temperature sensors in a heat pump system, which can provide a more accurate and reliable sensor status judgment scheme when the temperature change is affected by multiple factors.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for detecting inlet and outlet water temperature sensors in a heat pump system is provided, comprising the following steps:

[0007] S1: Determine the operating state of the compressor. If it is in the operating mode, proceed to step S2; if it is in the non-operating mode, proceed to step S4;

[0008] S2: Determine the cooling and heating operation mode of the unit: if it is heating mode or cooling mode, proceed to step S3; if it is defrosting mode, proceed to step S7;

[0009] S3: Define temperature difference thresholds T01 and T02, and T01<T02, and compare the difference between the inlet water temperature and the outlet water temperature and the coil temperature and the ambient temperature:

[0010] ① If in heating mode, the outlet water temperature - the inlet water temperature < T01, and the coil temperature < the ambient temperature, or in cooling mode, the inlet water temperature - the outlet water temperature < T01, and the coil temperature > the ambient temperature, then proceed to step S5;

[0011] ② If |inlet water temperature - outlet water temperature|>T02, proceed to step S5;

[0012] ③ If T01<|inlet water temperature - outlet water temperature|<T02, proceed to step S6;

[0013] S4: Define the temperature difference threshold T04, and T01≤T04<T02, and compare the difference between the inlet water temperature and the outlet water temperature:

[0014] If |water inlet temperature - water outlet temperature|>T04, proceed to step S5;

[0015] If |water inlet temperature - water outlet temperature|≤T04, proceed to step S6;

[0016] S5: It is determined that the water inlet temperature sensor or the water outlet temperature sensor is offset or failed, and the process proceeds to step S7;

[0017] S6: Determine that the water inlet temperature sensor or the water outlet temperature sensor is normal, and proceed to step S7;

[0018] S7: The process ends.

[0019] The present invention provides a new temperature sensor detection method. By combining the operating status of the compressor with the temperature difference, coil temperature and ambient temperature, it can more accurately determine whether the water inlet temperature sensor and the water outlet temperature sensor are offset or failed. Compared with the extreme detection means used in the prior art, which can only detect the failure of the temperature sensor and cannot detect when the offset occurs, the present invention has higher sensitivity. When the temperature sensor is detected to be offset or failed, it can be directly determined whether it is offset or failed according to the sensor status. If the sensor cannot be used directly, it is a failure; if the sensor can still be used, it means that an offset has occurred. The present invention has high detection accuracy and reliability, which is of great significance for improving the safety and stability of the compressor system. Among them, no failure judgment is performed in the defrosting state. The defrosting process is a short-term action. The system may not be in a stable state and no judgment is required.

[0020] Preferably, in step S5, when the compressor is in non-operating mode, when |inlet water temperature - outlet water temperature|>T04, the following steps are also included:

[0021] S51: Establish an exponential decay model for temperature change;

[0022] S52: Calculating the water inlet temperature range and / or the water outlet temperature range by using an exponential decay model;

[0023] S53: Determine whether the water inlet temperature is within the water inlet temperature range or the water outlet temperature is within the water outlet temperature range.

[0024] If the inlet water temperature is within the inlet water temperature range, or the outlet water temperature is not within the outlet water temperature range, it is determined that the outlet water temperature sensor is offset or failed;

[0025] If the inlet water temperature is not within the inlet water temperature range, or the outlet water temperature is within the outlet water temperature range, it is determined that the inlet water temperature sensor is offset or failed.

[0026] Preferably, the formula of the exponential decay model is as follows:

[0027] T(t)=T dyn _ env (t)+(T 0 -T dyn _ env (t))e -at1

[0028] Where: T(t) is the temperature at time t,

[0029] T 0 The initial temperature at 1 minute of shutdown, the initial temperature of water inlet or outlet,

[0030] The initial outlet water temperature is T 0出 ,

[0031] α is the attenuation coefficient, which indicates the rate of temperature change.

[0032] t1 is the time after shutdown, unit: hours or minutes,

[0033] T dyn_env (t) is the dynamic ambient temperature, which is affected by the indoor temperature and outdoor temperature;

[0034] Define Tin(t) as the inlet water temperature at time t, and the initial inlet water temperature is T 0进 ,but

[0035] Tin(t)=T dyn _ env (t)+(T 0 Enter-T dyn _ env (t))e -at1 ;

[0036] Define Tout(t) as the outlet water temperature at time t, and the initial outlet water temperature is T 0出 ,but

[0037] Tout(t)=T dyn_env (t)+(T 0出 -T dyn_env (t))e -at1 .

[0038] Preferably, the dynamic ambient temperature T dyn_env The formula for (t) is as follows:

[0039] T dyn_env (t) = T outdoor +k·(T indoor -T outdoor )

[0040] Where: T outdoor is the outdoor temperature, i.e. the ambient temperature;

[0041] T indoor is the indoor temperature;

[0042] k is a proportionality factor representing the efficiency of heat transfer between indoor and outdoor temperatures, <k<1。

[0043] Preferably, the water inlet temperature interval and / or water outlet temperature interval are calculated as follows:

[0044] Define the temperature threshold T03, then

[0045] Tin_min(t)=Tin(t)-T03

[0046] Tin_max(t)=Tin(t)+T03

[0047] Among them, Tin_min(t) is the minimum inlet water temperature, Tin_max(t) is the maximum inlet water temperature, and the inlet water temperature range is [Tin_min(t), Tin_max(t)];

[0048] Tout_min(t)=Tout(t)-T03

[0049] Tout_max(t)=Tout(t)+T03

[0050] Among them, Tout_min(t) is the minimum outlet water temperature, Tout_max(t) is the maximum outlet water temperature, and the outlet water temperature range is [Tout_min(t), Tout_max(t)].

[0051] Preferably, the heat conduction efficiency k between indoor and outdoor temperatures is adjusted according to different scenarios: when at the end of the fan coil unit, the indoor temperature has a greater impact on the water temperature change; when at the end of the floor heating system, the indoor temperature has a smaller impact on the water temperature change; therefore, the k value in the fan coil unit end scenario is greater than the k value in the floor heating system end scenario.

[0052] Preferably, the attenuation coefficient a is adjusted according to the thermal conductivity of the heat pump system, the thermal insulation of the material, and the rate of change of the ambient temperature.

[0053] Preferably, T01 is set to the lower limit of the typical temperature difference range between the inlet water temperature and the outlet water temperature under normal operating conditions, 0°C≤T01≤2°C.

[0054] Preferably, T02 is set to the upper limit of the typical temperature difference range between the inlet water temperature and the outlet water temperature under normal operating conditions, 10°C ≤ T02 ≤ 15°C.

[0055] Preferably, T04 is the temperature after the compressor is turned off. Since there is no heat source between the inlet water and the outlet water, the inlet water temperature and the outlet water temperature are the same under normal conditions, so 1°C≤T04≤3°C.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The present invention can determine whether the temperature sensor is offset. By combining the compressor operation mode (cooling / heating) and the exponential decay model, the sensor status can be monitored in real time whether the system is running or not. Unlike the prior art that only relies on the ambient temperature difference to make judgments, the present invention effectively avoids misjudgments caused by environmental fluctuations or differences in thermal insulation effects by dynamically calculating the allowable range of temperature changes. In addition, the present invention can quickly locate the problem when a temperature sensor fails, simplify the troubleshooting process, and improve the maintenance efficiency and service life of the equipment. In summary, the present invention provides a more accurate, reliable, and comprehensive temperature sensor failure detection solution with significant technical advantages and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The present invention is a flow chart of a method for detecting water inlet and water outlet temperature sensors in a heat pump system. DETAILED DESCRIPTION

[0059] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0061] Example 1

[0062] like Figure 1 The first embodiment of the method for detecting the inlet and outlet water temperature sensors in a heat pump system of the present invention is shown, comprising the following steps:

[0063] S1: Determine the operating state of the compressor. If it is in the operating mode, proceed to step S2; if it is in the non-operating mode, proceed to step S4;

[0064] S2: Determine the cooling and heating operation mode of the unit: if it is heating mode or cooling mode, proceed to step S3; if it is defrosting mode, proceed to step S7;

[0065] S3: Define temperature difference thresholds T01 and T02, and T01<T02, and compare the difference between the inlet water temperature and the outlet water temperature and the coil temperature and the ambient temperature:

[0066] T01 is set as the lower limit of the typical temperature difference between the inlet and outlet water temperatures under normal operating conditions, 0℃≤T01≤2℃;

[0067] Setting principle of parameter T01: T01 is a small temperature difference threshold, which is used to judge whether there is an abnormal temperature difference between the inlet and outlet water temperatures. Generally speaking, T01 should be set to the lower limit of the typical temperature difference range between the inlet and outlet water temperatures under normal operating conditions. The setting principle takes three points into consideration: (1) Based on the design characteristics of the system, according to the design of the heat pump system and the common temperature change law, the value of T01 should be set to take into account the temperature difference during normal operation of the heating and cooling modes. (2) Temperature stability. Considering the thermal insulation performance of the system and the influence of the external environment, T01 should be able to effectively eliminate misjudgments caused by environmental fluctuations and temporary temperature fluctuations. (3) Empirical value reference. Usually, T01 can be set to a relatively small value, such as 0℃ to 2℃, so that when the temperature difference is less than T01, it can be judged that there may be a problem with the sensor to avoid missing smaller offsets.

[0068] T02 is set as the upper limit of the typical temperature difference range between the inlet water temperature and the outlet water temperature under normal operating conditions, 10℃≤T02≤15℃;

[0069] Setting principle of parameter T02: T02 is a large temperature difference threshold used to detect whether there is an abnormal temperature difference between the inlet and outlet water temperatures. The value of T02 should be set to the upper limit of the typical temperature difference range between the inlet and outlet water temperatures under normal operating conditions. The setting principle considers three points: (1) Based on the typical operating temperature difference of the system, according to the working characteristics and design requirements of the system, T02 should be set to an upper limit that can reflect the temperature difference change under normal operating conditions of the system. For example, in heating mode, the temperature difference may be large, so a higher T02 value needs to be set. In cooling mode, the temperature difference may be small, so T02 should be appropriately reduced. (2) Consider the thermal load capacity of the equipment: The thermal load capacity and heat exchange efficiency of the equipment will also affect the inlet and outlet water temperature difference. In some high-efficiency systems, a large temperature difference may be normal, so the setting of T02 should take into account the actual thermal efficiency of the system. (3) Based on experience and test data: Experience values ​​and test data can be used as a reference for T02 setting. The common setting range is usually 10℃ to 15℃, and fine-tuning is performed according to the needs of specific equipment and environment.

[0070] ①In heating mode,

[0071] Outlet water temperature - inlet water temperature < T01,

[0072] And the coil temperature < ambient temperature, then go to step S5;

[0073] This condition applies to the case where the inlet water temperature is shifted upward or the outlet water temperature is shifted downward. If the inlet water temperature is mistakenly measured too high, or the outlet water temperature is measured too low, the system may mistakenly believe that the water temperature difference is small, resulting in reduced system efficiency. Further combined with the comparison of the coil temperature and the ambient temperature, it can be confirmed whether the heating operation is actually in progress to avoid being affected by the failure of the four-way valve switching. If the coil temperature is lower than the ambient temperature, it means that the system is heating normally, otherwise it means that the system is not heating normally;

[0074] Or in cooling mode,

[0075] Inlet water temperature - outlet water temperature < T01,

[0076] And the coil temperature>ambient temperature, then go to step S5;

[0077] This condition applies to the case where the inlet water temperature is shifted downward or the outlet water temperature is shifted upward. If the inlet water temperature is mistakenly measured too low, or the outlet water temperature is measured too high, the system may mistakenly believe that the water temperature difference is small, resulting in reduced system efficiency. Further combined with the comparison of the coil temperature and the ambient temperature, it can be confirmed whether the heating operation is actually in progress to avoid being affected by the failure of the four-way valve switching. If the coil temperature is higher than the ambient temperature, it means that the system is cooling normally, otherwise it means that the system is not cooling normally;

[0078] ② If |inlet water temperature - outlet water temperature|>T02, proceed to step S5;

[0079] In heating mode, the outlet water temperature is greater than the inlet water temperature;

[0080] |Inlet water temperature - outlet water temperature| = outlet water temperature - inlet water temperature > T02,

[0081] This condition applies when the inlet water temperature is shifted downward or the outlet water temperature is shifted upward. A large temperature difference may indicate that the outlet water temperature is incorrectly measured too high, or the inlet water temperature is incorrectly measured too low. At this point, the system needs to warn of a possible sensor failure;

[0082] In cooling mode, the inlet water temperature is greater than the outlet water temperature.

[0083] |Inlet water temperature - outlet water temperature| = Inlet water temperature - outlet water temperature > T02,

[0084] This condition applies to situations where the inlet water temperature is shifted upward or the outlet water temperature is shifted downward. A large temperature difference may indicate that the inlet water temperature is incorrectly measured too high, or the outlet water temperature is incorrectly measured too low. At this point, the system needs to warn of a possible sensor failure;

[0085] ③ If T01<|inlet water temperature - outlet water temperature|<T02, proceed to step S6;

[0086] S4: Define the temperature difference threshold T04, and T01≤T04<T02, and compare the difference between the inlet water temperature and the outlet water temperature:

[0087] Parameter T04 setting principle: after the compressor is turned off, there is no heat source between the inlet and outlet water. Under normal conditions, the inlet and outlet water temperatures are the same. Considering the fluctuation of the temperature sensor, T04 should be set with a margin. The setting range can be referenced to 1°C to 3°C.

[0088] T04 is the temperature after the compressor is turned off. Since there is no heat source between the inlet and outlet water, the inlet and outlet water temperatures are the same under normal conditions, so 1℃≤T04≤3℃;

[0089] If |water inlet temperature - water outlet temperature|>T04, proceed to step S5;

[0090] If |water inlet temperature - water outlet temperature|≤T04, proceed to step S6;

[0091] S5: It is determined that the water inlet temperature sensor or the water outlet temperature sensor is offset or failed, and the process proceeds to step S7;

[0092] When the compressor is in non-operating mode, when |inlet water temperature - outlet water temperature|>T04, the following steps are also included:

[0093] S51: Establish an exponential decay model for temperature change;

[0094] It is assumed that the inlet or outlet water temperature will gradually approach the ambient temperature according to the exponential decay model after shutdown. The formula of the exponential decay model is as follows:

[0095] T(t)=T dyn _ env (t)+(T 0 -T dyn _ env (t))e -at1

[0096] Where: T(t) is the temperature at time t,

[0097] T 0 The initial temperature at 1 minute of shutdown, representing the initial temperature of the water inlet or outlet.

[0098] α is the attenuation coefficient, which indicates the rate of temperature change.

[0099] t1 is the time after shutdown, unit: hours or minutes,

[0100] T dyn_env (t) is the dynamic ambient temperature, which is affected by the indoor temperature and outdoor temperature;

[0101] Define Tin(t) as the inlet water temperature at time t, and the initial inlet water temperature is T 0进 ,but

[0102] Tin(t)=T dyn_env (t)+(T 0进 -T dyn_env (t))e -at1 ;

[0103] Define Tout(t) as the outlet water temperature at time t, and the initial outlet water temperature is T 0出 ,but

[0104] Tout(t)=T dyn_env (t)+(T 0出 -T dyn_env (t))e -at1 ;

[0105] Among them, the dynamic ambient temperature T dyn_env The formula for (t) is as follows:

[0106] T dyn_env (t) = T outdoor +k·(T indoor -T outdoor )

[0107] Where: T outdoor is the outdoor temperature, i.e. the ambient temperature;

[0108] T indoor is the indoor temperature;

[0109] k is a proportionality factor representing the efficiency of heat transfer between indoor and outdoor temperatures, <k<1;

[0110] The basic concept of temperature decay: The temperature decay model describes how the temperature gradually approaches the ambient temperature after the system stops. Specifically, when the heat pump system or equipment stops running, due to the difference between the ambient temperature and the internal temperature of the equipment, the temperature will gradually approach the ambient temperature over time, and this process usually shows an exponential decay characteristic.

[0111] The physical meaning of the attenuation coefficient: The attenuation coefficient a determines the rate of temperature change. In practical applications, the attenuation coefficient a depends on factors such as the thermal conductivity of the system, the thermal insulation of the material, and the rate of change of the ambient temperature. When the attenuation coefficient a is large, it means that the temperature changes faster; conversely, when the attenuation coefficient a is small, the temperature changes slower. By reasonably selecting the value of a, the temperature attenuation behavior of the device under different environmental conditions can be more accurately simulated.

[0112] Dynamic ambient temperature: In order to adapt the model to different application scenarios, we need to dynamically adjust the ambient temperature T dyn_env (t) to adapt to the change of indoor and outdoor temperature difference. For example, suppose that in some environments, the temperature decays slowly (such as when the outdoor temperature is very low), while in other environments, the decay rate is fast (such as when the outdoor temperature is high), so T dyn_env (t) will be adjusted according to different environmental conditions;

[0113] T dyn_env (t) is the dynamic ambient temperature, i.e. the final temperature during the temperature decay process.

[0114] By (T 0 -T dyn_env (t)), we represent the initial difference between the system temperature and the ambient temperature. This means that at time t = 0, the system temperature deviates from the ambient temperature by an initial difference (i.e., T0).

[0115] e -at1 The part represents the rate of temperature change, and the amount of change decreases as time goes by. When t1→∞, the exponential term approaches zero, and the system temperature eventually approaches the ambient temperature;

[0116] k parameter setting principle: We can adjust parameters according to different scenarios;

[0117] The heat pump system includes core components such as compressor, expansion valve, and heat exchanger. Among them, the heat exchanger has different classifications according to the different heat sources. In the air source heat pump system, the indoor unit releases heat to the room through fan coil or floor heating system. When the end of the heat pump system uses fan coil or floor heating system, the value of k will be different accordingly.

[0118] S52: Calculating the water inlet temperature range and / or the water outlet temperature range by using an exponential decay model;

[0119] The system calculates the expected temperatures Tin(t) and Tout(t) of the inlet and outlet water at time t, and further defines an allowable temperature range, i.e., the upper and lower limits of the temperature, as the intervals within which the inlet and outlet water temperatures should fall:

[0120] Define the temperature threshold T03, then

[0121] Tin_min(t)=Tin(t)-T03

[0122] Tin_max(t)=Tin(t)+T03

[0123] Among them, Tin_min(t) is the minimum value of the inlet water temperature, Tin_max(t) is the maximum value of the inlet water temperature, and the inlet water temperature range is [Tin_min(t), Tin_max(t)];

[0124] Tout_min(t) = Tout(t) - T03

[0125] Tout_max(t) = Tout(t) + T03

[0126] Among them, Tout_min(t) is the minimum value of the outlet water temperature, Tout_max(t) is the maximum value of the outlet water temperature, and the outlet water temperature range is [Tout_min(t), Tout_max(t)];

[0127] S53: Determine whether the inlet water temperature is within the inlet water temperature range or whether the outlet water temperature is within the outlet water temperature range.

[0128] When the compressor has been turned off for 1 minute, first compare the difference between the inlet water temperature and the outlet water temperature. If the difference is too large, it is determined that the inlet water temperature sensor or the outlet water temperature sensor may be offset or failed; further judge the temperature change range of the inlet water temperature and the outlet water temperature to determine which temperature sensor may be offset or failed:

[0129] If the inlet water temperature is within the inlet water temperature range, or the outlet water temperature is not within the outlet water temperature range, it is determined that the outlet water temperature sensor is offset or failed;

[0130] If the inlet water temperature is not within the inlet water temperature range, or the outlet water temperature is within the outlet water temperature range, it is determined that the inlet water temperature sensor is offset or failed;

[0131] S6: Determine that the inlet water temperature sensor or the outlet water temperature sensor is normal, and enter step S7;

[0132] S7: The process ends.

[0133] The failure judgment is not carried out in the defrosting state. The defrosting process is a short-time action, and the system may not be in a stable state, so there is no need to judge.

[0134] Specific examples are as follows:

[0135] Example ①:

[0136] When the compressor is in a non-operating state, at this time, define the temperature difference threshold T04 as 1.5 °C, the inlet water temperature is 9 °C, the outlet water temperature is 8 °C, |inlet water temperature - outlet water temperature| = 1 °C < T04, then it is determined that the inlet water temperature sensor or the outlet water temperature sensor is normal.

[0137] Example ②:

[0138] When the compressor is not in operation, the temperature difference threshold T04 is defined as 1.5°C, the inlet water temperature is 10°C, the outlet water temperature is 8°C, and |inlet water temperature - outlet water temperature| = 2°C > T04. It is determined that the inlet water temperature sensor or the outlet water temperature sensor is offset or failed. Next, it is determined which temperature sensor has a problem:

[0139] Exponential decay model based on temperature change:

[0140] T(t)=T dyn_env (t)+(T 0 -T dyn_env (t))e -at1

[0141] Among them, T outdoor -20℃, T indoor is 20℃, k is 0.3, then

[0142] T dyn_env (t) = T outdoor +k·(T indoor -T outdoor )=-8℃

[0143] T 0进 is 35℃, a is 0.2, t1 is 5, T03 is 2, then the calculated Tin(t) is 7.82,

[0144] Tin_min(t)=Tin(t)-T03=5.82

[0145] Tin_max(t)=Tin(t)+T03=9.82

[0146] The inlet water temperature range is [5.82, 9.82], and the inlet water temperature of 10°C is not within the inlet water temperature range, so it is judged that the inlet water temperature sensor is offset.

[0147] Example 2

[0148] The following is a second embodiment of a method for detecting the inlet and outlet water temperature sensors in a heat pump system of the present invention. This embodiment is similar to the first embodiment, except that when at the end of the fan coil, the end of the fan coil is usually greatly affected by the indoor temperature because the efficiency of heat dissipation through the fan is high and the indoor temperature fluctuates rapidly. In this case, the dynamic ambient temperature T dyn_env (t) The effect of indoor temperature on water temperature should be considered, and a higher k value should be set so that k is close to 1, indicating that the indoor temperature has a greater impact on the change of water temperature.

[0149] Example 3

[0150] The following is a third embodiment of a method for detecting the inlet and outlet water temperature sensors in a heat pump system of the present invention. This embodiment is similar to the first embodiment, except that when at the end of the floor heating system, since the end of the floor heating system is usually relatively stable, its water temperature is more significantly affected by the indoor temperature. However, since the floor heating pipes are usually buried in the floor, the insulation effect is better, so the ambient temperature changes slowly, and the decay process may be even slower. Therefore, in the temperature decay model at the end of the floor heating system, the dynamic ambient temperature T dyn_env (t) should be set to a lower k value so that the k value is close to 0, indicating that the indoor temperature has less influence on the water temperature change.

[0151] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for detecting inlet and outlet water temperature sensors in a heat pump system, characterized in that: The following steps are involved: S1: Determine the operating state of the compressor. If it is in the operating mode, proceed to step S2; If it is in non-operating mode, proceed to step S4; S2: Determine the cooling and heating operation mode of the unit: if it is heating mode or cooling mode, proceed to step S3; if it is defrosting mode, proceed to step S7; S3: Define temperature difference thresholds T01 and T02, and T01<T02, and compare the difference between the inlet water temperature and the outlet water temperature and the coil temperature and the ambient temperature: ① If in heating mode, the outlet water temperature - the inlet water temperature < T01, and the coil temperature < the ambient temperature, or in cooling mode, the inlet water temperature - the outlet water temperature < T01, and the coil temperature > the ambient temperature, then proceed to step S5; ② If |inlet water temperature - outlet water temperature|>T02, proceed to step S5; ③ If T01<|inlet water temperature - outlet water temperature|<T02, proceed to step S6; S4: Define the temperature difference threshold T04, and T01≤T04<T02, and compare the difference between the inlet water temperature and the outlet water temperature: If |water inlet temperature - water outlet temperature|>T04, proceed to step S5; If |water inlet temperature - water outlet temperature|≤T04, proceed to step S6; S5: It is determined that the water inlet temperature sensor or the water outlet temperature sensor is offset or failed, and the process proceeds to step S7; S6: Determine that the water inlet temperature sensor or the water outlet temperature sensor is normal, and proceed to step S7; S7: The process ends.

2. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 1, characterized in that: In step S5, when the compressor is in non-operating mode, when |inlet water temperature - outlet water temperature|>T04, the following steps are also included: S51: Establish an exponential decay model for temperature change; S52: Calculating the water inlet temperature range and / or the water outlet temperature range by using an exponential decay model; S53: Determine whether the water inlet temperature is within the water inlet temperature range or the water outlet temperature is within the water outlet temperature range. If the inlet water temperature is within the inlet water temperature range, or the outlet water temperature is not within the outlet water temperature range, it is determined that the outlet water temperature sensor is offset or failed; If the inlet water temperature is not within the inlet water temperature range, or the outlet water temperature is within the outlet water temperature range, it is determined that the inlet water temperature sensor is offset or failed.

3. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 2, characterized in that: The formula of the exponential decay model is as follows: T(t)=T dyn _ env (t)+(T0-T dyn _ env (t))e -at1 Where: T(t) is the temperature at time t, T0 is the initial temperature at 1 minute of shutdown, the initial temperature of water inlet or outlet. α is the attenuation coefficient, which indicates the rate of temperature change. t1 is the time after shutdown, unit: hours or minutes, T dyn_env (t) is the dynamic ambient temperature, which is affected by the indoor temperature and outdoor temperature; Define Tin(t) as the inlet water temperature at time t, and the initial inlet water temperature is T 0进 ,but Tin(t) = T dyn _ env (t)+(T0 in - T dyn _ env (t))e -at1 ; Define Tout(t) as the outlet water temperature at time t, and the initial outlet water temperature is T 0出 ,but Tout(t) = T dyn _ env (t) + (T0 out - T dyn _ env (t))e -at1 。 4. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 3, characterized in that: Dynamic ambient temperature T dyn_env The formula for (t) is as follows: T dyn_env (t)=T outdoor +k·(T indoor -T outdoor ) Where: T outdoor is the outdoor temperature, i.e. the ambient temperature; T indoor is the indoor temperature; k is a proportionality factor representing the efficiency of heat transfer between indoor and outdoor temperatures, <k<1。 5. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 4, characterized in that: The calculation of the inlet water temperature range and / or the outlet water temperature range is as follows: Define the temperature threshold T03, then Tin_min(t)=Tin(t)-T03 Tin_max(t)=Tin(t)+T03 Among them, Tin_min(t) is the minimum inlet water temperature, Tin_max(t) is the maximum inlet water temperature, and the inlet water temperature range is [Tin_min(t), Tin_max(t)]; Tout_min(t)=Tout(t)-T03 Tout_max(t)=Tout(t)+T03 Among them, Tout_min(t) is the minimum outlet water temperature, Tout_max(t) is the maximum outlet water temperature, and the outlet water temperature range is [Tout_min(t), Tout_max(t)].

6. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 4, characterized in that: The parameters of the heat conduction efficiency k between indoor and outdoor temperatures are adjusted according to different scenarios: when at the end of the fan coil unit, the indoor temperature has a greater impact on the water temperature change; when at the end of the floor heating system, the indoor temperature has a smaller impact on the water temperature change; therefore, the k value in the fan coil unit end scenario is greater than the k value in the floor heating system end scenario.

7. The method for detecting the inlet and outlet water temperature sensors in a heat pump system according to claim 3, characterized in that: The attenuation coefficient a is adjusted according to the heat conduction properties of the heat pump system, the thermal insulation properties of the material and the rate of change of the ambient temperature.

8. The method for detecting water inlet and water outlet temperature sensors in a heat pump system according to claim 1, characterized in that: T01 is set as the lower limit of the typical temperature difference range between the inlet water temperature and the outlet water temperature under normal operating conditions, 0℃≤T01≤2℃.

9. The method for detecting water inlet and outlet temperature sensors in a heat pump system according to claim 1, characterized in that: T02 is set as the upper limit of the typical temperature difference range between the inlet water temperature and the outlet water temperature under normal operating conditions, 10℃≤T02≤15℃.

10. The method for detecting water inlet and water outlet temperature sensors in a heat pump system according to claim 1, characterized in that: T04 is the temperature after the compressor is turned off. Since there is no heat source between the inlet water and the outlet water, the inlet water temperature and the outlet water temperature are the same under normal conditions, so 1℃≤T04≤3℃.

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