阅读说明：本技术 一种基于模糊分区结霜图谱的控霜方法 (Frost control method based on fuzzy partition frosting map ) 是由 王智伟 岳泓辰 魏鹏 王笙 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种基于模糊分区结霜图谱的控霜方法,包括：对室外环境温度、相对湿度进行监测,判断空气状态点是否处在结霜区；依据结霜图谱制定的模糊控制规则,判断空气状态点在结霜区的区域,给出结霜速率；根据计算霜层厚度控制热泵机组开始除霜；根据机组实际除霜时间判断是否结束除霜；根据除霜效果,对结霜速率和蒸发器盘管表面设定温度进行自调整。本发明将结霜图谱与模糊控制相结合,提高了结霜程度判断的准确性,避免了误除霜,延长了机组的使用寿命。该方法简单实用,可行性大。(The invention discloses a frost control method based on a fuzzy partition frosting map, which comprises the following steps: monitoring the outdoor environment temperature and the relative humidity, and judging whether the air state point is in a frosting area; judging the area of the air state point in the frosting area according to a fuzzy control rule formulated by a frosting map, and giving a frosting rate; controlling a heat pump unit to start defrosting according to the calculated frost layer thickness; judging whether defrosting is finished or not according to the actual defrosting time of the unit; the rate of frost and the evaporator coil surface set temperature are self-adjusted based on the effectiveness of the defrost. The invention combines the frosting map with fuzzy control, improves the accuracy of judging the frosting degree, avoids mistaken defrosting and prolongs the service life of the unit. The method is simple and practical and has high feasibility.)

1. A frost control method based on a fuzzy partition frosting map is characterized by comprising the following steps:

step 1: for outdoor ambient temperature T_aMonitoring relative humidity RH, judging whether the air state point is in a frosting area U, if so, performing the next step, otherwise, monitoring again;

step 2: inputting the outdoor environment temperature and humidity frosting monitoring values into a fuzzy controller, judging which area of a frosting area the air state point is specifically located in according to a fuzzy control rule formulated by a frosting map, and simultaneously giving a frosting rate calculation value;

and step 3: calculating the thickness h of the frost layer under the heating working condition by using the frosting rate in the step 2_iWhen the thickness of the frost layer exceeds 1/2 of the distance d between the fins of the evaporator coil of the outdoor heat pump unit, the heat pump unit starts defrosting, and the actual defrosting time tau of the unit is carried out₂And evaporator coil surface temperature T_wMonitoring, otherwise, returning to the step 2;

and 4, step 4: when the unit actually defrosts time tau₂Not less than minimum heating time tau of unit₁After 10%, entering judgment of ending defrosting, otherwise, monitoring actual defrosting time tau of the unit again₂And evaporator coil surface temperature T_w；

And 5: surface temperature T of evaporator coil_wGreater than or equal to the set temperature T of the surface of the evaporator coil_sAnd defrosting is finished; otherwise, the actual defrosting time tau of the unit is set₂Judging; when the unit actually defrosts time tau₂Reaching the minimum heating time tau of the unit₁20%, defrosting is finished, otherwise, the actual defrosting time tau of the heat pump unit is monitored again₂And evaporator coil surface temperature T_w；

Step 6: evaluating the starting point and effect of last defrosting, calculating the frosting speed v and the set temperature T of the surface of the evaporator coil_sSelf-adjustment is performed.

2. The frost control method based on the fuzzy partition frosting map of claim 1, wherein in step 1, the air condition point in the frosting area is satisfied with both the ambient temperature being lower than 6 ℃ and the relative humidity being higher than 50%.

3. The frost control method based on the fuzzy partition frosting map of claim 1, wherein in step 1, the outdoor environment temperature T is measured_aAnd the relative humidity RH is divided into a severe frosting area PB, a heavy frosting area PS, a moderate frosting area O, a light frosting area NS and a light frosting area NB from large to small, and the frosting area U is divided into the severe frosting area PB, the heavy frosting area PS, the moderate frosting area O, the light frosting area NB and the light frosting area NS from heavy frosting to light frosting.

4. The frost control method based on the fuzzy partition frosting map of claim 3, wherein in step 2, according to fuzzy inference rules of fuzzy controller, it is determined which region of the frosting area the air state point is in the blurred map, and an initial calculated value of frosting rate v is given: the initial set value of the speed of each frosting area is the median of the interval, the frosting speed of the light frosting area NB is 0.1mm/h, the frosting speed of the light frosting area NS is 0.35mm/h, the frosting speed of the medium frosting area O is 0.7mm/h, the frosting speed of the heavy frosting area PS is 1.1mm/h, and the frosting speed of the heavy frosting area PB is 1.6 mm/h.

5. The frost control method based on the fuzzy partition frosting map according to claim 4, wherein the fuzzy inference rule is:

6. the frost control method based on the fuzzy partition frosting map according to claim 1, wherein in the step 3, the thickness of the frost layer under the heating condition is calculated as follows:

h_i＝h_i-1+vΔτ

wherein h is_iIs the thickness of the frost layer in i time intervals, i is the number of times the time interval is recorded, h_i-1The growth thickness of the frost layer in the first i-1 time intervals, Δ τ is the time interval monitored, and v is the frost formation rate.

7. The frost control method based on the fuzzy partition frosting map according to claim 1, wherein in the step 6, the method for evaluating the defrosting starting point and the defrosting effect is as follows:

instantaneous heating quantity q if the unit starts defrosting₂Greater than the instantaneous heating capacity q in the frostless process₁70% of (a), the frosting rate calculated by v is reduced by 0.02 mm/h; instantaneous heating quantity q if the unit starts defrosting₂Instantaneous heating capacity q less than or equal to frostless process₁70% of (A), the frost-formation rate, calculated v, increases by 0.02 mm/h.

8. The method as claimed in claim 1, wherein in step 6, the calculated frosting rate v and the set surface temperature of the evaporator coil are calculatedT_sSelf-adjustment is carried out by the following method:

after heat supply is recovered, if the heat pump unit heats the heat quantity q₃Instantaneous heating capacity q in frostless process or more₁And 95 percent of the total temperature, the evaporation temperature set value is reduced by 0.1 ℃; if the heating capacity q of the heat pump unit₃Less than instantaneous heating capacity q in frostless process₁95% of the evaporation temperature set point, the evaporation temperature set point is increased by 0.1 deg.c.

Technical Field

The invention relates to the field of air source heat pump frost control, in particular to a frost control method based on a fuzzy partition frosting map.

Background

The performance of the air source heat pump is greatly influenced by outdoor environment parameters, and when the surface temperature of the evaporator fin is lower than the dew point temperature of air and lower than the freezing point in winter, the surface of the evaporator can be frosted. The frosting can produce adverse effect to the operation of the air source heat pump unit, and the unit is stopped when the frosting is serious, so the defrosting must be carried out when the air source heat pump frosts. The existing typical defrosting control methods can be divided into two types, namely a time-based defrosting control method and a defrosting demand-based defrosting control method. The time-based control method is serious in 'false defrosting', and temperature or pressure parameters are usually increased and are used as defrosting criteria together with time. Temperature is not the only condition affecting frost formation and air pressure differentials are susceptible to evaporator surface conditions, both of which can lead to "false defrost". The existing control method based on the defrosting requirement generally needs to add hardware equipment on the original unit, so that the manufacturing cost is increased and the control method is not easy to realize.

Different meteorological characteristics lead to the frost degree difference, to the frost degree judge rationally can realize "defrosting as required". The frosting map is an effective tool for researching the frosting degree, and the frosting rate can be quickly obtained by acquiring the ambient temperature and humidity. The frosting map is divided into a frosting area, a dewing area and a non-frosting area, and the frosting area is divided into five areas by the frosting rate curve, namely a light frosting area, a medium frosting area, a heavy frosting area and a heavy frosting area. In practice, however, the partitions of the frosting area have uncertainty, five areas should not have definite boundaries, and the fuzzy control can solve the problem of boundary ambiguity well through fuzzification, defuzzification and self-adaptation. The fuzzy controller can be used for fuzzifying the map to fuzzify the partition boundary of the map, and meanwhile, the frosting map is used as expert experience to provide reference for formulating a fuzzy frost control rule. However, the frosting map has certain limitations in terms of the frosting distribution condition obtained by a certain unit under specific conditions, and needs to be adjusted by using a fuzzy control adaptive mechanism, so that the system continuously learns to reach a satisfactory working state, and the universality of the system is improved to adapt to different regions and units.

Disclosure of Invention

In order to solve the problem of 'false defrosting' in the conventional defrosting control, a frosting map is combined with fuzzy control, a frosting rate is given by judging the frosting degree by using a fuzzy controller, and the frosting thickness is calculated, so that a defrosting starting point is reasonably selected.

The purpose of the invention is realized by the following technical scheme.

A frost control method based on a fuzzy partition frosting map comprises the following steps:

step 1: for temperature and humidity T of outdoor environment_aMonitoring relative humidity RH, judging whether the air state point is in a frosting area U, if so, performing the next step, otherwise, monitoring again;

step 2: inputting the outdoor environment temperature and humidity frosting monitoring values into a fuzzy controller, judging which area of a frosting area the air state point is specifically located in according to a fuzzy control rule formulated by a frosting map, and simultaneously giving a frosting rate calculation value;

and step 3: calculating the thickness h of the frost layer under the heating working condition by using the frosting rate in the step 2_iWhen the thickness of the frost layer exceeds 1/2 of the distance d between the fins of the evaporator coil of the outdoor heat pump unit, the heat pump unit starts defrosting, and the actual defrosting time tau of the unit is carried out₂And evaporator coil surface temperature T_wMonitoring, otherwise, returning to the step 2;

and 4, step 4: when the unit actually defrosts time tau₂Not less than minimum heating time tau of unit₁After 10%, entering judgment of ending defrosting, otherwise, monitoring actual defrosting time tau of the unit again₂And evaporator coil surface temperature T_w；

And 5: surface temperature T of evaporator coil_wGreater than or equal to the surface set temperature T of the evaporator_sAnd defrosting is finished; otherwise, the actual defrosting time tau of the unit is set₂Judging; when the unit actually defrosts time tau₂Reaching the minimum heating time tau of the unit₁20%, defrosting is finished, otherwise, the actual defrosting time tau of the heat pump unit is monitored again₂And evaporator coil surface temperature T_w；

Step 6: evaluating the defrosting starting point and the defrosting effect of the last time, and calculating the frosting rate v and the set temperature T of the surface of the evaporator coil_sSelf-adjustment is performed.

Further, in the step 1, an air state point where the ambient temperature is lower than 6 ℃ and the relative humidity is higher than 50% is in the frosting area.

Further, in the step 1, the outdoor temperature T is adjusted_aAnd the relative humidity RH is divided into a severe frosting area PB, a heavy frosting area PS, a moderate frosting area O, a light frosting area NB and a light frosting area NS from large to small, and the frosting area U is divided into the severe frosting area PB, the heavy frosting area PS, the moderate frosting area O, the light frosting area NB and the light frosting area NS from severe frosting to light frosting.

Further, in the step 2, according to fuzzy inference rules of the fuzzy controller, which area of the frosting area the air state point is in is judged in the blurred map, and an initial calculated value of the frosting rate v is given: the initial set value of the speed of each frosting area is the median of the interval, the frosting speed of the light frosting area NB is 0.1mm/h, the frosting speed of the light frosting area NS is 0.35mm/h, the frosting speed of the medium frosting area O is 0.7mm/h, the frosting speed of the heavy frosting area PS is 1.1mm/h, and the frosting speed of the heavy frosting area PB is 1.6 mm/h.

Further, in step 6, the method for evaluating the defrosting starting point and the defrosting effect is as follows:

instantaneous heating quantity q if the unit starts defrosting₂Greater than the instantaneous heating capacity q in the frostless process₁70% of the above, the calculated frosting rate v is reduced by 0.02 mm/h; instantaneous heating capacity q of the unit if defrosting is started₂Instantaneous heating capacity q less than or equal to frostless process₁70% of (A), the calculated frosting rate v increases by 0.02 mm/h.

Further, in the step 6, the calculated value of the frosting rate v and the set temperature T of the surface of the evaporator coil_sSelf-adjustment is carried out by the following method:

after the heat supply is recovered, if the unit heats the quantity q₃Instantaneous heating capacity q in frostless process or more₁And 95 percent of the total temperature, the evaporation temperature set value is reduced by 0.1 ℃; if the unit heats the quantity q₃Less than instantaneous heating capacity q in frostless process₁95% of the evaporation temperature set point, the evaporation temperature set point is increased by 0.1 deg.c.

The invention has the beneficial effects that:

compared with the prior art, the frosting map is combined with the fuzzy control, the map is used as a basis for formulating the control rule, the control rule is more reasonable, meanwhile, the fuzzy control fuzzifies the subareas of different frosting areas of the map, the accuracy of judging the frosting degree is improved, and more accurate control is realized. The frosting degree is judged by the fuzzy controller, different frosting rate calculation values are given according to different frosting degrees, the frosting thickness is accurately calculated, the 'wrong defrosting' is avoided, and meanwhile, a self-adjusting mechanism is used for adjusting the rate value, so that the frosting map is adaptive to an application area. The 'wrong defrosting' is reduced, the energy consumption of the unit is reduced, and the service life is prolonged. The defrosting on demand is realized on the premise of not increasing the complexity of the system, hardware equipment is not required to be added, only a soft method is loaded in the original control method, and the method is simple, practical and high in feasibility.

Drawings

Fig. 1 is a flowchart of a defrost control method.

Detailed Description

The detailed description is given to the specific implementation of the regional frosting map-based frost control method provided by the invention, but the detailed description is not taken as a basis for limiting the invention.

Referring to the attached figure 1, the invention relates to a frost control method based on a fuzzy partition frosting map, which comprises the following steps:

step 1: for outdoor ambient temperature T_aAnd monitoring the relative humidity RH, judging whether the air state point is in a frosting area U, if so, carrying out the next step, otherwise, monitoring again.

Wherein the outdoor ambient temperature T is measured_aAnd the relative humidity RH is divided into a severe frosting area PB, a heavy frosting area PS, a moderate frosting area O, a light frosting area NB and a light frosting area NS from large to small, and the frosting area U is divided into the severe frosting area PB, the heavy frosting area PS, the moderate frosting area O, the light frosting area NB and the light frosting area NS from severe frosting to light frosting. The air condition point in the frosting zone is such that both the ambient temperature is below 6 ℃ and the relative humidity is above 50%.

Step 2: the outdoor environment temperature and humidity frosting monitoring value is input into a fuzzy controller, a fuzzy control rule formulated by a frosting map is used for judging which area of a frosting area the air state point is specifically located in, and a frosting rate calculation value is given at the same time.

And judging which area of the frosting area the air state point is in the blurred map according to the fuzzy inference rule of the fuzzy controller. The fuzzy inference rule table is shown in table 1.

TABLE 1 fuzzy inference rule Table

The fuzzy inference rule is as follows:

(1) temperature T_aIn the severe frosting zone PB:

the relative humidity RH is located in the severe frosting area PB, the heavy frosting area PS, and the moderate frosting area O, and then the frosting area U where the air state point is located is determined as the severe frosting area PB;

the relative humidity RH is located in the lighter frosting area NS, and then the frosting area U where the air state point is located is determined as a severe frosting area O;

the relative humidity RH is in the light frosting area NB, and then the frosting area U where the air state point is located is determined as the light frosting area NB.

(2) Temperature T_aIn the severe frosting area PS:

the relative humidity RH is located in the severe frosting area PB, and then the frosting area U where the air state point is located is determined as the severe frosting area PB;

the relative humidity RH is located in the heavy frosting area PS, and then the frosting area U where the air state point is located is determined as the heavy frosting area PS;

the relative humidity RH is located in the moderate frosting area O, and then the frosting area U where the air state point is located is determined as the moderate frosting area O;

the relative humidity RH is located in the light frosting area NS, and then the frosting area U where the air state point is located is determined as the light frosting area NS;

the relative humidity RH is located in the light frosting area NB, and then the frosting area U where the air state point is located is judged as the light frosting area NB;

(3) temperature T_aIn the moderate frosting zone O:

the relative humidity RH is located in the severe frosting area PB and the heavy frosting area PS, and then the frosting area U where the air state point is located is determined as the heavy frosting area PS;

the relative humidity RH is located in the moderate frosting area O, and then the frosting area U where the air state point is located is determined as the moderate frosting area O;

the relative humidity RH is located in the lighter frosting area NS and the light frosting area NB, and then the frosting area U where the air state point is located is determined as the light frosting area NB;

(4) temperature T_aIn the less frosted zone NS:

the relative humidity RH is located in the severe frosting area PB and the heavy frosting area PS, and then the frosting area U where the air state point is located is determined as the moderate frosting area O;

the relative humidity RH is located in the moderate frosting area O, and then the frosting area U where the air state point is located is judged as a lighter frosting area NS;

the relative humidity RH is located in the lighter frosting area NS and the light frosting area NB, and then the frosting area U where the air state point is located is determined as the light frosting area NB;

(5) temperature T_aIn the mild frosting zone NB:

the relative humidity RH is located in the severe frosting area PB and the heavy frosting area PS, and then the frosting area U where the air state point is located is determined as the light frosting area NS;

the relative humidity RH is located in the moderate frosting area O, the light frosting area NS, and the light frosting area NB, and then the frosting area U where the air condition point is located is determined as the light frosting area NB.

According to fuzzy inference rules of a fuzzy controller, judging which region of the frosting area the air state point is in the blurred map, and giving an initial calculated value of the frosting rate v: the initial set value of the speed of each frosting area is the median of the interval, the frosting speed of the light frosting area NB is 0.1mm/h, the frosting speed of the light frosting area NS is 0.35mm/h, the frosting speed of the medium frosting area O is 0.7mm/h, the frosting speed of the heavy frosting area PS is 1.1mm/h, and the frosting speed of the heavy frosting area PB is 1.6 mm/h.

And step 3: calculation of frosting Rate Using step 2Thickness h of frost layer under heating working condition_iWhen the thickness of the frost layer exceeds 1/2 of the distance d between the fins of the evaporator coil of the outdoor heat pump unit, the heat pump unit starts defrosting, and the actual defrosting time tau of the unit is carried out₂And evaporator coil surface temperature T_wAnd monitoring, otherwise, returning to the step 2.

Calculating the thickness of the frost layer under the heating working condition:

h_i＝h_i-1+vΔτ

wherein h is_iIs the thickness of the frost layer in i time intervals, i is the number of times the time interval is recorded, h_i-1The growth thickness of the frost layer in the first i-1 time intervals, Δ τ is the time interval monitored, and v is the frost formation rate.

And 4, step 4: when the unit actually defrosts time tau₂Not less than minimum heating time tau of unit₁After 10%, entering judgment of ending defrosting, otherwise, monitoring actual defrosting time tau of the unit again₂And evaporator coil surface temperature T_w。

And 5: surface temperature T of evaporator coil_wGreater than or equal to the set temperature T of the surface of the evaporator coil_sDefrosting and frosting; otherwise, the actual defrosting time tau of the unit is set₂Judging; when the unit actually defrosts time tau₂Reaching the minimum heating time tau of the unit₁20%, defrosting is finished, otherwise, the actual defrosting time tau of the heat pump unit is monitored again₂And evaporator coil surface temperature T_w。

Step 6: evaluating the starting point and effect of last defrosting, calculating the frosting speed v and the set temperature T of the surface of the evaporator coil_sSelf-adjustment is performed.

The method for evaluating the defrosting starting point and the defrosting effect comprises the following steps:

instantaneous heating quantity q if the unit starts defrosting₂Greater than the instantaneous heating capacity q in the frostless process₁70% of (a), the frosting rate calculated by v is reduced by 0.02 mm/h; instantaneous heating quantity q if the unit starts defrosting₂Instantaneous heating capacity q less than or equal to frostless process₁70% of (A), the frost-formation rate, calculated v, increases by 0.02 mm/h.

Calculated value of frost formation rate v and set temperature T of evaporator coil surface_sSelf-adjustment is carried out by the following method:

after heat supply is recovered, if the heat pump unit heats the heat quantity q₃Instantaneous heating capacity q in frostless process or more₁And 95 percent of the total temperature, the evaporation temperature set value is reduced by 0.1 ℃; if the heating capacity q of the heat pump unit₃Less than instantaneous heating capacity q in frostless process₁95% of the evaporation temperature set point, the evaporation temperature set point is increased by 0.1 deg.c.

The following different examples are given to further illustrate the invention.