Disclosure of Invention
An object of the present invention is to provide an exhaust gas temperature control method for controlling the exhaust gas temperature within a reasonable range without reducing the amount of heat generated by a unit.
The second objective of the present invention is to provide a controller for storing and executing the above control method.
The invention also aims to provide an air energy heat pump unit comprising the controller.
In order to achieve the purpose, the invention adopts the following technical scheme:
an exhaust temperature control method is applied to an air energy low-temperature variable-frequency heat pump unit, and the method is used for controlling the exhaust temperature of the air energy low-temperature variable-frequency heat pump unitThe control method is operated when the enhanced vapor injection compressor is in an operating state, and comprises the following steps: setting a first-stage exhaust temperature protection value T1Second stage exhaust temperature protection value T2And an exhaust temperature control exit temperature T11Wherein, T2>T1>T11(ii) a Detecting the current exhaust temperature Tpq in real time when the enhanced vapor injection compressor is in an operating state; if the current exhaust temperature Tpq exceeds the first-stage exhaust temperature protection value T1And does not exceed the secondary exhaust temperature protection value T2Then the opening of the injection enthalpy valve is increased until the current exhaust temperature Tpq is lower than the exhaust temperature control exit temperature T11(ii) a If the current exhaust temperature Tpq exceeds the secondary exhaust temperature protection value T2Then the opening degree of the injection enthalpy valve is increased and the opening degree of the throttle valve is decreased until the current exhaust temperature Tpq is lower than the exhaust temperature control exit temperature T11。
Further, the current exhaust temperature Tpq and the exhaust temperature control exit temperature T11The size of the difference is positively correlated with the opening adjustment quantity of the enthalpy injection valve.
Further, the difference between the current exhaust temperature Tpq and the exhaust temperature before adjustment is positively correlated with the opening adjustment amount of the enthalpy injection valve.
Further, the control step of adjusting the opening of the enthalpy injection valve is as follows: recording the opening of the enthalpy injection valve at the previous moment as EXV by taking the time interval S as a periodn-1Exhaust temperature of Tpqn-1Simultaneously recording the opening of the enthalpy injection valve at the current moment as EXVnExhaust temperature of Tpqn(ii) a Calculating the opening EXV = EXV of the enthalpy injection valve at the later momentn-1+KP1*(Tpqn-T11)+KD1*(Tpqn-Tpqn-1) Wherein, KP1Is the exhaust proportional coefficient of the enthalpy injection valve, KD1Is the exhaust differential coefficient of the enthalpy injection valve; adjusting the opening degree of the enthalpy injection valve according to the calculated value, and simultaneously recording the adjusted opening degree value as EXVn。
Further, the current exhaust temperature Tpq and the exhaust temperature control exit temperature T11The magnitude of the difference is inversely related to the opening adjustment amount of the throttle valve.
Further, the magnitude of the difference between the current exhaust temperature Tpq and the pre-throttle exhaust temperature is inversely related to the amount of adjustment of the opening degree of the throttle valve.
Further, the control step of adjusting the opening degree of the throttle valve is: recording the opening of the throttle valve at the previous moment as EVI by taking time interval S as a periodn-1Exhaust temperature of Tpqn-1Simultaneously recording the opening of the throttle valve at the current moment as EVInExhaust temperature of Tpqn(ii) a Calculating the throttle opening EVI = EVI at the later momentn-1-KP2*(Tpqn-T11)-KD2*(Tpqn-Tpqn-1) Wherein, KP2For throttle exhaust proportionality coefficient, KD2Is a throttle exhaust differential coefficient; adjusting the opening of the throttle valve according to the calculated value, and recording the adjusted opening value as EVIn。
A controller comprising a memory for storing a computer program and a processor for executing the computer program to implement the exhaust temperature control method described above.
The utility model provides an air energy heat pump unit, is including forming the jet enthalpy-increasing compressor, indoor heat exchanger, economizer, choke valve and the outdoor heat exchanger in the heating loop, wherein, laid on the branch pipeline of indoor heat exchanger and economizer intercommunication and spout the enthalpy valve, the economizer have with the gas vent of jet enthalpy-increasing compressor middle part induction port intercommunication, heat pump unit is still including the cross valve that is used for refrigeration and heat conversion, and the neighbour locates the exhaust temperature sensor of jet enthalpy-increasing compressor gas outlet is close to the ambient temperature sensor that outdoor heat exchanger installed, and respectively with spout the controller that enthalpy valve, choke valve, exhaust temperature sensor and ambient temperature sensor connect, the controller is foretell controller.
By adopting the technical scheme, the invention at least has the following beneficial effects: the exhaust temperature control method is particularly suitable for the conditions that the outdoor environment temperature is lower than minus 25 ℃, the compression ratio of the unit is high, and the operation is unstable, and the exhaust temperature is controlled by setting a secondary exhaust temperature control step under the condition of not reducing the heating capacity of the unitThe control is in a reasonable range to ensure the stable and efficient operation of the unit; specifically, when the exhaust temperature exceeds a first-stage exhaust temperature protection value T1And does not exceed the secondary exhaust temperature protection value T2When the method is used, the adjustment and increase control of the injection enthalpy valve is carried out, and the exhaust temperature can be effectively controlled or reduced by increasing the injection enthalpy quantity; if the opening degree of the injection enthalpy valve is adjusted, the exhaust temperature continuously rises and exceeds a secondary exhaust temperature protection value T2And the flow of the enthalpy injection valve is increased under the condition of the same opening degree by adjusting and reducing the opening degree of the throttle valve, the enthalpy injection quantity entering the compressor is sufficient, the exhaust temperature is effectively controlled, the unit operates stably and reliably, and the energy efficiency ratio is improved.
Detailed Description
In order to make the technical features, objects and effects of the present invention more clearly understood, a detailed description of embodiments of the present invention will be given below with reference to the accompanying drawings.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that a typical air-energy heat pump unit includes a compressor, an indoor heat exchanger 9, a throttle valve 7, and an outdoor heat exchanger 4, which are connected in sequence through a refrigerant pipe, and a four-way valve 3 is included if cooling and heating conversion is required, and the four-way valve 3 is an electromagnetic valve.
Referring to fig. 1, the air energy low-temperature variable-frequency heat pump unit adopted by the invention is particularly suitable for northern areas with low outdoor environment temperature, when the outdoor environment temperature is reduced to below-25 ℃, the evaporation temperature is usually below-30 ℃, so when hot water with the temperature of above 50 ℃ is required to be prepared, the compression ratio of the system is high, the exhaust temperature is extremely high, and the reliability of the system operation is influenced. Therefore, the compressor of the heat pump unit is an enhanced vapor injection compressor 1, and further comprises an economizer 6 and a controller, wherein the economizer 6 is connected in series with a refrigerant pipeline between an indoor heat exchanger 9 and a throttle valve 7, an enthalpy injection valve 8 is arranged on a branch pipeline for communicating the economizer 6 with the indoor heat exchanger 9, and the economizer 6 is provided with an exhaust port communicated with a middle air suction port of the enhanced vapor injection compressor 1. The enthalpy injection valve 8 and the throttle valve 7 are electronic expansion valves, but may be other components as needed. The indoor heat exchanger 9 is preferably a plate heat exchanger, and the outdoor heat exchanger 4 is preferably a fin heat exchanger.
In order to dynamically acquire parameter values of each component of the unit, various sensing elements need to be arranged. For example, the temperature sensor for detecting temperature or the pressure sensor for detecting pressure, the present invention includes a discharge temperature sensor 2 adjacent to the outlet of the enhanced vapor injection compressor 1 and an ambient temperature sensor 5 installed near the outdoor heat exchanger 4.
The controller of the invention is respectively connected with the enthalpy injection valve 8, the throttle valve 7, the exhaust temperature sensor 2 and the ambient temperature sensor 5. Comprising a memory for storing a computer program and a processor for executing the computer program to implement the exhaust gas temperature control method described below.
Referring to fig. 2, the method for controlling the exhaust temperature according to the present invention specifically includes the following steps based on the operation state of the enhanced vapor injection compressor 1:
s1: detecting the current exhaust temperature Tpq in real time, and recording the exhaust temperature Tpq at the previous moment by taking the time interval S as a periodn-1The opening degree of the enthalpy injection valve 8 is EXVn-1And the opening of the throttle valve 7 is EVIn-1(ii) a Simultaneously recording the exhaust temperature at the current moment as TpqnThe opening degree of the enthalpy injection valve 8 is EXVnAnd the opening of the throttle valve 7 is EVIn。
S2: and judging whether the unit meets the enthalpy injection exhaust control conditions or not, and if so, entering enthalpy injection exhaust control.
Specifically, the conditions for satisfying the enthalpy injection exhaust gas control include:
one of the conditions is that the current exhaust temperature Tpq exceeds a primary exhaust temperature guard value T1;
the second condition is that the current exhaust temperature Tpq is not lower than the exhaust temperature control exit temperature T11;
Wherein, one of the conditions is an entering condition of the enthalpy injection exhaust gas control, and the other of the conditions is a step of continuously operating the enthalpy injection exhaust gas control when the unit operates in the enthalpy injection exhaust gas control and the condition is satisfied.
S3: the enthalpy injection exhaust control steps are as follows:
calculating the opening EXV = EXV of the enthalpy injection valve 8 at the later momentn-1+KP1*(Tpqn-T11)+KD1*(Tpqn-Tpqn-1) Wherein, KP1Is the exhaust proportional coefficient of the enthalpy injection valve, KD1Is the exhaust differential coefficient of the enthalpy injection valve;
adjusting the opening degree of the enthalpy injection valve 8 according to the calculated value, and simultaneously recording the adjusted opening degree value as EXVn。
In the calculation formula of the opening degree of the injection enthalpy valve 8 at the latter time of the present invention, the exhaust temperature Tpq is calculated from the current timenControlling the exit temperature T with the exhaust temperature11The difference value is multiplied by an enthalpy injection valve exhaust proportional coefficient KP1Calculating the number of the opening degrees required to be adjusted and increased, and achieving the purpose that the opening degree is adjusted and increased when the distance between the exhaust temperature and the exhaust temperature control exit temperature is larger; further, by comparing the current exhaust temperature Tpq with the pre-regulation exhaust temperatureThe difference is multiplied by an exhaust differential coefficient KD of the enthalpy injection valve1And calculating the opening degree required to be adjusted and increased, and achieving the purpose that the opening degree is increased when the exhaust temperature changes, so that the change condition of the exhaust temperature after the opening degree of the enthalpy injection valve is adjusted at the previous moment can be fully considered, the opening degree of the enthalpy injection valve can be adjusted more truly and accurately, and the exhaust temperature is ensured to be controlled.
S4: when the condition Tpq < T is satisfied11And when the enthalpy injection exhaust control is not performed, the enthalpy injection exhaust control is stopped.
S5: judging whether the condition Tpq > T is satisfied2And if the requirements are met, the throttle exhaust control is started.
Wherein the parameter value T2The protection value of the secondary exhaust temperature is preset by a user according to the actual environment temperature.
It should be noted that the preset temperature parameter value T1,T2And T11The relation between is T2>T1>T11And synchronously executing the enthalpy injection exhaust control step when the unit enters the throttling exhaust control.
S6: the throttling exhaust control steps are as follows:
the opening degree EVI = EVI of the throttle valve 7 at the latter time is calculatedn-1-KP2*(Tpqn-T11)-KD2*(Tpqn-Tpqn-1) Wherein, KP2For throttle exhaust proportionality coefficient, KD2Is a throttle exhaust differential coefficient;
adjusting the opening of the throttle valve 7 based on the calculated value, and recording the adjusted opening as EVIn。
In the calculation formula of the opening degree of the throttle valve 7 at the later time of the present invention, the exhaust temperature Tpq is calculated from the current timenControlling the exit temperature T with the exhaust temperature11Is multiplied by a throttle exhaust proportionality coefficient KP2Calculating the opening number required to be adjusted and reduced, and achieving the purpose that the opening adjustment and reduction are larger when the distance between the exhaust temperature and the exhaust temperature control exit temperature is larger; further, the difference between the current exhaust temperature Tpq and the pre-regulation exhaust temperature is multiplied by a throttle exhaust differential coefficient KD2Meter for measuringThe opening number required to be adjusted is calculated, and the purpose that the opening number is adjusted to be larger when the exhaust temperature changes is larger is achieved, so that the change condition of the exhaust temperature after the opening of the throttle valve is adjusted at the previous moment can be fully considered, the opening of the throttle valve can be adjusted more truly and accurately, and the exhaust temperature is ensured to be controlled.
S7: when the condition Tpq < T is satisfied11And when the throttle exhaust control is exited.
The following are described: the exhaust temperature control exit temperature in the opening formula of the enthalpy injection valve 8 is the same as that in the opening formula of the throttle valve 7, so that the control targets of the exhaust temperature in the process of executing the control steps by the enthalpy injection valve 8 and the throttle valve 7 are consistent, the exhaust temperature is prevented from being reduced to a safe range due to the conflict of the exhaust temperature targets, the regulation and control result is influenced, and the operation reliability of a unit is further influenced.
It should be noted that the proportionality coefficient KP1、KD1、KP2And KD2And specific numerical values can be determined through experiments according to the difference of the system, so that the exhaust control is ensured to be rapid, timely and stable.
According to the exhaust temperature control method, the secondary exhaust temperature control step is arranged, so that the exhaust temperature is controlled within a reasonable range under the condition that the heating capacity of the unit is not reduced, and the unit can be ensured to operate stably and efficiently; specifically, when the exhaust temperature exceeds a first-stage exhaust temperature protection value T1And does not exceed the secondary exhaust temperature protection value T2When the method is used, the adjustment and increase control of the injection enthalpy valve is carried out, and the exhaust temperature can be effectively controlled or reduced by increasing the injection enthalpy quantity; if the opening degree of the injection enthalpy valve is adjusted, the exhaust temperature continuously rises and exceeds a secondary exhaust temperature protection value T2And meanwhile, the adjustment and reduction control of the throttle valve is synchronously carried out, because the total flow of the unit is constant, the flow of the enthalpy injection valve 8 is increased under the condition of the same opening degree by adjusting and reducing the opening degree of the throttle valve 7, the enthalpy injection quantity entering the compressor is sufficient, the exhaust temperature is effectively controlled, the unit operates stably and reliably, and the energy efficiency ratio is improved.
The exhaust temperature control method of the present invention will be described in detail below with reference to specific examples:
s00: in thatBefore the heat pump unit is started, relevant parameters are set: t is1=100℃、T11=95℃、T2=105℃、KP1=KP2=2、KD1=KD2=1、S=10S。
S10: when the enhanced vapor injection compressor 1 is in operation, the current time Tpq is detected by the unitn=99℃、EXVn=180、EVIn= 240; the related data stored at the previous moment is Tpqn-1=98℃、EXVn=170、EVIn=250;TpqnNon-compliance TpqnNot less than 100 ℃ or TpqnNot less than 105 deg.c, so that enthalpy injection exhaust control and throttle exhaust control are not introduced.
S20: after the interval time of 10S, the unit detects Tpqn=103℃、EXVn=180、EVIn= 240; the related data stored at the previous moment is Tpqn-1=99℃、EXVn-1=180、EVIn-1=240。
S30:TpqnSatisfy TpqnThe temperature (103 ℃) is not less than 100 ℃, the unit enters into enthalpy injection exhaust control, and the opening degree of the enthalpy injection valve at the later moment is calculated according to the following formula:
EXV=EXVn-1+KP1*(Tpqn-T11)+KD1*(Tpqn-Tpqn-1)
=180+2*(103-95)+1*(103-99)
=200;
the enthalpy injection valve is adjusted in opening degree according to 200 steps, and the opening degree after being adjusted in place is recorded as EXVnI.e. EXVn=200。
S40:TpqnUnsatisfied with Tpqn(103 ℃) is equal to or more than 105 ℃, so that the throttling exhaust control is not carried out.
S50 after interval time 10S, the unit detects Tpqn=106℃、EXVn=200、EVIn=240, relevant data saved at previous moment is Tpqn-1=103℃、EXVn-1=200、EVIn-1=240。
S60:TpqnSatisfy Tpqn(106 ℃) is not less than 100 ℃, and the unit enters into enthalpy injection exhaust control:
the opening of the enthalpy injection valve 8 is calculated according to the following formula:
EXV=EXVn-1+KP1*(Tpqn-T11)+KD1*(Tpqn-Tpqn-1)
=200+2*(106-95)+1*(106-103)
=225;
the enthalpy injection valve 8 is adjusted in opening degree according to 225 steps, and the opening degree after being adjusted in place is recorded as EXVnI.e. EXVn=225。
S70:TpqnSatisfy Tpqn(106 ℃) is equal to or more than 105 ℃, so the throttling exhaust control is performed:
the opening degree of the throttle valve 7 is calculated according to the following formula:
EVI=EVIn-1-KP2*(Tpqn-T11)-KD2*(Tpqn-Tpqn-1)
=240-2*(106-95)-1*(106-103)
=215;
the throttle valve 7 is adjusted in opening degree according to step 215, and the opening degree after being adjusted in place is recorded as EVInI.e. EVIn=215。
S80: after the interval time of 10S, the unit detects Tpqn=94℃、EXVn=225、EVIn=215, the relevant data saved at the previous moment is Tpqn-1=106℃、EXVn-1=200、EVIn-1=240。
S90: at the moment, the condition Tpq (94 ℃) is less than or equal to T11(95 ℃), and enthalpy injection exhaust control and throttle exhaust control are quitted.
In the description of the present invention, "controller", "processor", and the like may include hardware, software, or a combination of both. A module may comprise hardware circuitry, various suitable sensors, communication ports, memory, may comprise software components such as program code, or may be a combination of software and hardware. The processor may be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and/or signal processing functionality. The processor may be implemented in software, hardware, or a combination thereof. The physical device to which the controller corresponds may be the processor itself, or a part of software, a part of hardware, or a part of a combination of software and hardware in the processor.
It should be noted that although the control method has been described above with reference to specific sequences of steps, those skilled in the art will appreciate that the various steps are not necessarily performed in such a sequence, and may be performed simultaneously (in parallel) or in other sequences to achieve the effects of the present invention, and that such variations are within the scope of the present invention.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.