KR102326374B1 - Power switching module having the isolated gate driver - Google Patents

Abstract

The present invention relates to a method for measuring a virtual air volume of a variable air volume terminal unit, and more particularly, a damper having a high correlation with the inlet/outlet differential pressure (damper differential pressure) among the inlet/outlet differential pressure, damper opening rate, and supply fan speed factors in the terminal unit. The present invention relates to a method for measuring a virtual air volume of a variable air volume terminal unit in which two variables, an opening rate and a supply fan speed, are replaced with input factors, and the virtual air volume formed in the form of a constant function is calculated and measured accordingly.

Description

Virtual air volume measurement method of variable air volume terminal unit {Power switching module having the isolated gate driver}

The present invention relates to a method for measuring the virtual air volume of a variable air volume terminal unit, and more particularly, to replace two variables of a damper opening rate and a supply fan speed in the terminal unit with input factors, and thus form a constant function. The present invention relates to a method for measuring a virtual air volume of a variable air volume terminal unit for calculating and measuring a virtual air volume.

In general, there are a constant air volume system (C.A.V system) and a variable air volume system (V.A.V system) as a method of maintaining the temperature of a space using air as a medium.

The constant air volume method is a method of compensating by changing the supply air temperature in response to a load change while maintaining a constant supply air flow rate, and the variable air volume method is a method of compensating by changing the supply air temperature in response to a load change and making the supply air temperature constant. way.

The application of the double variable air volume method is expanding because it is easy to save energy and control individually.

An air conditioning system using such a variable air volume method includes an exhaust duct that forms a passage through which indoor air is discharged to the outside, and an exhaust damper that adjusts the amount of exhaust discharged through the exhaust duct.

In addition, an air supply duct supplied from the air conditioner to the room, an air flow measurement device for measuring an air supply amount, and a static pressure sensor for measuring the pressure of air passing through the air supply duct are installed. An air supply fan is installed in the air supply duct to control the amount of air supplied to the room, and the flow measuring station (FMS) measures the dynamic pressure of the air supplied to the room, and the measured dynamic pressure and the area of the air volume measurement device The air supply is calculated by

Then, a variable air volume terminal unit (VAV) is installed on the air supply duct of the variable air volume air conditioning system.

The variable air volume terminal unit calculates the maximum air volume according to the indoor load in order to keep the supply air temperature constant and compensate for the load change by changing the air supply air volume, and calculates the minimum air volume at a level of 30-50% of the maximum air volume. do.

Therefore, in order to save energy, it is important to determine the minimum air volume when setting the standard of the variable air volume terminal unit.

However, in the prior art, it was difficult to set the set value of the minimum air volume low due to indoor environmental problems such as air quality and temperature stratification at a place where the variable air volume terminal unit is used.

In addition, the air volume measuring sensor used in the variable air volume terminal unit generally uses a pitot tube anemometer, but when the wind speed is low, the precision of the sensor is reduced and it is difficult to secure control stability.

Therefore, although a hot wire anemometer can be used to measure the wind speed at a low speed, since the hot wire anemometer is expensive compared to the Pitot tube anemometer, the overall cost of the air conditioning system can be increased.

Therefore, in order to effectively control the minimum air volume of the variable air volume terminal unit, there is a need to develop a low-cost and high-accuracy air volume measurement method.

On the other hand, as prior art for variable air volume type air conditioning system, the technology of variable air volume bypass type air conditioner and control method of Korean Patent Registration No. 10-1015962 and the variable air volume control device of Korean No. 10-1105730 No. 10-1105730 Techniques and techniques of variable air volume air conditioners and methods of Korean Patent Registration No. 10-483691 are known.

Republic of Korea Patent No. 10-1015962 Republic of Korea Patent No. 10-1105730

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, to provide a low-cost and high-accuracy air volume sensing method for effectively controlling the minimum air volume of a variable air volume terminal unit.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

The configuration of the method for measuring the virtual air volume of the variable air volume terminal unit of the present invention for achieving the above object is to change the damper opening rate of the terminal unit at the maximum fan speed while performing on-site measurement of the variable air volume terminal unit and to change the damper differential pressure and measuring the air volume, fixing the damper opening rate of the variable air volume terminal unit to a minimum, changing the fan speed, and measuring the damper differential pressure and air volume. a second step of varying the damper opening rate at the maximum fan speed measured in step 1 and deriving a damper performance curve using the measured values of the damper differential pressure and air volume of the terminal unit; a third step of varying the damper opening rate at the maximum fan speed measured in the first step and deriving a relational expression between the damper opening rate and the differential pressure ratio using the measured values of the damper differential pressure and air volume of the terminal unit; a fourth step of varying the supply fan speed at the minimum damper opening rate measured in step 1 and deriving a relational expression between the fan speed and the damper differential pressure using the measured value of the damper differential pressure of the terminal unit; Step 5 of deriving a formula for estimating the virtual air volume of the variable air volume terminal unit using the damper performance curve derived from steps 1 to 4, the relational expression between the damper opening rate and the differential pressure ratio, and the fan speed and the damper differential pressure relationship. It is characterized in that it comprises.

According to the method for measuring the virtual air volume of the variable air volume terminal unit of the present invention according to the above configuration, the conventional variable air volume terminal unit has a disadvantage in that it is difficult to secure the stability of the control because the precision of the sensor is reduced when the wind speed is low. The variable air volume terminal unit of the present invention does not need to use a separate air volume sensor when the wind speed is low, thereby reducing the manufacturing cost of the variable air volume terminal unit and improving the accuracy of air volume measurement using the variable air volume terminal unit. It has the effect of securing the control stability of the air conditioning system.

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a graph of the air volume measurement result according to the change in the minimum air volume set value of the variable air volume terminal unit;
2 is a graph of the air flow characteristic curve diagram of the damper;
3 is a graph of the air volume of the variable air volume terminal unit and the damper differential pressure;
4 is a flowchart of a method for measuring a virtual air volume of a variable air volume terminal unit according to the present invention;
5 is a block diagram of a target air conditioning system to which the method for measuring air volume of the present invention is applied;
6 is a graph of a damper performance curve derived by the method for measuring air volume of the present invention;
7 is a graph showing the relationship between the damper opening rate and the damper differential pressure ratio derived by the method for measuring air volume of the present invention;
8 is a graph showing the relationship between the damper opening rate and the differential pressure ratio at the maximum fan speed derived by the method for measuring air volume of the present invention;
9 is a graph showing the relationship between the damper differential pressure and the fan speed according to the fan speed derived by the method for measuring the air volume of the present invention;
10 is a graph showing the uncertainty when applying the method for measuring air volume of the present invention;
11 is a graph showing a long-term test result of a virtual air volume sensor according to the method for measuring air volume of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be “connected (connected, contacted, coupled)” with another part, it is not only “directly connected” but also “indirectly connected” with another member interposed therebetween. "Including cases where In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a method for virtually measuring air volume in a variable air volume terminal unit, and the conventional variable air volume terminal unit has a disadvantage in that it is difficult to secure control stability because the precision of the sensor is reduced when the wind speed is low. The variable air volume terminal unit of the present invention does not need to use a separate air volume sensor when the wind speed is low, thereby reducing the manufacturing cost of the variable air volume terminal unit and improving the accuracy of air volume measurement. The effect of securing the control stability of the harmonic system is expressed.

To this end, the method for measuring the virtual air volume of the variable air volume terminal unit of the present invention has a high correlation with the differential pressure (damper differential pressure) between the inlet and outlet of the variable air volume terminal unit in order to more efficiently measure the air volume supplied to the inside of the variable air volume terminal unit. The need to use a separate air volume sensor is eliminated by replacing the two variables, the damper opening rate and the supply fan speed, as input factors, and thus calculating the virtual air volume in the form of a constant function.

Hereinafter, a method for measuring the virtual air volume of the variable air volume terminal unit of the present invention will be described in detail with reference to the accompanying drawings.

First, in order to implement the method for measuring the virtual air volume of the variable air volume terminal unit of the present invention, the supply air volume according to the change of the set value of the minimum air volume was analyzed in order to check the precision of the air volume sensor of the variable air volume terminal unit according to the minimum air volume operation. .

The variable air volume terminal unit used for this analysis is a terminal unit including a reheat coil, and the control air volume range is 0-1360CMH, and a terminal unit capable of air volume monitoring and control using the Building Automation System (BAS) was selected.

In addition, the set value of the minimum air volume was set to 500CMH (50% of the maximum air volume) and 250CMH (25% of the maximum air volume), and the air volume was measured at 1-minute intervals through the BAS.

1 is an air flow measurement result according to a change in a minimum air volume set value of a variable air volume terminal unit.

Referring to the drawings, when the set value of the minimum air volume of the variable air volume terminal unit is 500 CMH, the measured supply air volume is 480 ~ 524 CMH, which confirms the reliability within 5% of the set value.

In addition, after changing to 250CMH as the set value of the minimum air volume, the result of measuring the supplied air volume was 0 to 346CMH, confirming that the air volume detection accuracy of the air volume sensor was low and the stability of the air volume control was insufficient.

In addition, the variable air volume terminal unit is composed of a wind speed sensor, a damper, and a reheat coil, and a wind speed sensor is installed at the entrance of the variable air volume terminal unit to control the air volume supplied to each zone, and the air volume is checked through the wind speed sensor, Control the airflow by adjusting the damper opening rate.

At this time, the damper used in the variable air volume terminal unit has unique characteristics according to the type and size, and has a relationship between the air volume and the differential pressure according to the change in the opening rate.

The damper is used for adjusting the imbalance of the air volume, changing the air volume, and partially sealing. Classification by shape includes butterfly type, louver type (parallel type, opposed wing), split type and slide type.

The most commonly used type of damper is a louver-type damper. A louver-type damper is a damper with two or more blades. There is an opposing-wing method, but the opposing-wing method has superior airflow characteristics.

In addition, the control performance of the damper can be expressed as the ratio of the pressure loss when the damper is not installed in the duct system and the pressure loss when the damper is fully open as shown in Equation 1 below, and the air flow characteristic curve of the damper is As shown in FIG. 2 .

(Equation 1)

Referring to FIG. 2 , it can be confirmed that the air volume passing through the damper for air volume control is linearly proportional to the damper opening rate and the pressure loss, and the possibility of calculating the air volume can be confirmed based on this.

Therefore, the method for measuring the virtual air volume of the terminal unit of the variable air volume of the present invention, which will be described below, provides a virtual air volume sensing technology using the inlet/outlet differential pressure of the terminal unit, the damper opening rate, and the supply fan speed in order to secure control stability, A field application procedure was established accordingly.

In addition, the reliability of the virtual air volume sensor was evaluated by analyzing the uncertainty of the input factor and comparing it with the conventional method for measuring air volume.

Hereinafter, a method for measuring the virtual air volume of the variable air volume terminal unit according to the present invention will be described in detail.

As described above, the air conditioning system influence factors that affect the air volume of the variable air volume terminal unit include a damper opening rate, a damper differential pressure, and a supply fan speed.

The damper performance curve of the variable air volume terminal unit can be expressed as a quadratic equation between the air volume and the damper differential pressure at the maximum speed, and can be calculated through Equation (2).

At this time, in order to derive the coefficients (a1, a2, a3) of the damper performance curve, the air volume and the damper differential pressure must be measured while changing the damper opening rate at the maximum speed of the supply fan.

(Equation 2)

(여기서, P_dp,f는 공급팬 최대스피드일 때 변풍량 터미널 유닛 댐퍼 차압, a₀, a₁, a₂는 댐퍼 성능 곡선 계수, Q_f는 공급팬 최대스피드일 때 변풍량 터미널 유닛 풍량)

(Where P _dp,f is the variable air volume terminal unit damper differential pressure at the maximum supply fan speed, a ₀ , a ₁ , a ₂ are the damper performance curve coefficients, Q _f is the variable air volume terminal unit air volume at the maximum supply fan speed)

3 is a graph of the air volume of the variable air volume terminal unit and the differential pressure of the damper, and it can be seen that the damper opening rate and the speed of the supply fan change. Based on Equation 3, it can be corrected using Equation 3, and Equation 4 can be derived.

Also, by using Equation 5, the air volume of the variable air volume terminal unit may be calculated using the fan speed and the damper differential pressure as input values.

(Equation 3)

(여기서, P_dp,f는 공급팬 최대스피드일 때 변풍량 터미널 유닛 댐퍼 차압, P_dp,p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 댐퍼 차압,

는 공급팬 최대스피드,

는 공급팬 부분스피드, Q_f는 공급팬 최대스피드일 때 변풍량 터미널 유닛 풍량, Q_p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 풍량)

(Where, P _dp,f is the differential pressure of the terminal unit damper with variable air volume when the supply fan is at the maximum speed, P _dp,p is the differential pressure of the damper of the terminal unit with the variable air when the partial speed of the supply fan is used.

is the maximum feed fan speed,

is the partial speed of the supply fan, Q _f is the terminal unit air volume when the supply fan is at the maximum speed, Q _p is the air volume of the terminal unit when the supply fan is the partial speed)

(Equation 4)

(여기서, P_dp,p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 댐퍼 차압, a₀, a₁, a₂는 댐퍼 성능 곡선 계수, Q_p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 풍량,

는 공급팬 스피드 비)

(Where P _dp,p is the variable air volume terminal unit damper differential pressure at the partial speed of the supply fan, a ₀ , a ₁ , a ₂ are the damper performance curve coefficients, Q _p is the air volume of the terminal unit variable air volume at the partial speed of the supply fan,

is the supply fan speed ratio)

(Equation 5)

(여기서, P_dp,p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 댐퍼 차압, a₀, a₁, a₂는 댐퍼 성능 곡선 계수, Q_p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 풍량,

는 공급팬 스피드 비)

(Where P _dp,p is the variable air volume terminal unit damper differential pressure at the partial speed of the supply fan, a ₀ , a ₁ , a ₂ are the damper performance curve coefficients, Q _p is the air volume of the terminal unit variable air volume at the partial speed of the supply fan,

is the supply fan speed ratio)

However, it is necessary to additionally install a damper differential pressure sensor in order to measure the virtual air volume of the variable air volume terminal unit, and in a building having a plurality of terminal units, it is costly to install the damper differential pressure sensor at all points.

Therefore, in the method for measuring the virtual air volume of the variable air volume terminal unit of the present invention, the relationship between the damper opening rate and the damper differential pressure, which are one of the control factors of the variable air volume terminal unit, is analyzed, and the damper differential pressure is replaced and used as an input value.

That is, the damper differential pressure can be measured by opening the damper opening to the minimum and changing the fan speed.

In this case, the relationship between the damper opening rate and the damper differential pressure ratio can be derived as a cubic equation as shown in Equation 6 below.

In addition, the damper differential pressure ratio can be expressed as the ratio of the partial damper differential pressure to the damper maximum differential pressure value for the same fan speed, as shown in Equation (7).

(Equation 6)

(Equation 7)

(여기서, β는 변풍량 터미널 유닛 차압비, b₀, b₁, b₂는 댐퍼 개도율-차압비 관계 계수, P_dp,p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 댐퍼 차압, P_dp,max는 변풍량 터미널 유닛 최대 차압)

(Where β is the differential pressure ratio of the terminal unit of the variable air volume, b ₀ , b ₁ , and b ₂ are the damper opening degree-differential pressure ratio relation coefficients, and P _dp,p is the differential pressure of the differential pressure of the terminal unit damper at the supply fan partial speed, P _{dp ,max} is the variable air volume terminal unit maximum differential pressure)

In addition, the damper maximum differential pressure can be derived according to each fan speed change, which is expressed in Equation (8).

(Equation 8)

(여기서, P_dp,max는 변풍량 터미널 유닛 최대 차압,

는 공급팬 스피드 비, c₀, c₁, c₂, c₃은 공급팬 스피드 비- 최대차압 관계 계수)

(Where P _dp,max is the maximum differential pressure of the variable air volume terminal unit,

is the supply fan speed ratio, c ₀ , c ₁ , c ₂ , and c ₃ are the supply fan speed ratio-maximum differential pressure relation coefficient)

Therefore, by synthesizing Equation 6, Equation 7 and Equation 8, Equation 9 expressed as the damper opening rate and fan speed with respect to the measured differential pressure can be derived.

In addition, by synthesizing Equations 5 and 9, Equation 10 representing the virtual air volume sensing equation of the final variable air volume terminal unit may be derived.

(Equation 9)

(여기서, α는 변풍량 터미널 유닛 댐퍼 개도율, β는 변풍량 터미널 유닛 차압비, b₀, b₁, b₂는 댐퍼 개도율-차압비 관계 계수, c₀, c₁, c₂, c₃는 공급팬 스피드 비- 최대차압 관계 계수, P_dp,p는 공급팬 부분스피드일 때 변풍량 터미널 유닛 댐퍼 차압, P_dp,max는 변풍량 터미널 유닛 최대 차압)

(where α is the variable air volume terminal unit damper opening rate, β is the variable air volume terminal unit differential pressure ratio, b ₀ , b ₁ , b ₂ is the damper opening degree-differential pressure ratio relationship coefficient, c ₀ , c ₁ , c ₂ , c ₃ is the supply fan speed ratio-maximum differential pressure relation coefficient, P _dp,p is the variable air volume terminal unit damper differential pressure at partial supply fan speed, P _dp,max is the variable air volume terminal unit maximum differential pressure)

(Equation 10)

(여기서, Q_p=공급팬 부분스피드일 때 변풍량 터미널 유닛 풍량, a₀, a₁, a₂는 댐퍼 성능 곡선 계수, b₀, b₁, b_2, b₃는 댐퍼 개도율-차압비 관계 계수, c₀, c₁, c₂, c₃는 공급팬 스피드 비- 최대차압 관계 계수, α는 변풍량 터미널 유닛 댐퍼 개도율, Q_p는 댐퍼 개도율이 p일 때의 풍량,

는 공급팬 스피드 비)

(Where, Q _p = variable air volume at partial speed of supply fan terminal unit air volume, a ₀ , a ₁ , a ₂ are damper performance curve coefficients, b ₀ , b ₁ , b _{2 ,} b ₃ are damper opening degree-differential pressure ratio relationship coefficient, c ₀ , c ₁ , c ₂ , c ₃ are the supply fan speed ratio-maximum differential pressure relation coefficient, α is the variable air volume terminal unit damper opening rate, Q _p is the air volume when the damper opening rate is p,

is the supply fan speed ratio)

Next, according to the virtual air volume sensing value calculated as described above, a hot wire anemometer, a differential pressure sensor, and a BAS system capable of controlling and measuring the damper opening rate and fan speed are prepared and the air volume is measured according to the following procedure. 4 is a flowchart illustrating steps 1 to 5 of the method for measuring air volume of the present invention, which will be described below.

Step 1: Conduct the field measurements at VAV terminal unit (see Fig. 4)

Conduct on-site measurement of the variable air volume terminal unit, but measure it twice.

In the first measurement, at the maximum fan speed, change the damper opening rate of the terminal unit and measure the damper differential pressure and air volume (or wind speed).

In the second measurement, after setting the damper opening rate of the terminal unit to the minimum, change the fan speed and measure the damper differential pressure and air volume (or wind speed).

Step 2: Create damper performance curve (see Figure 4)

At the maximum fan speed measured in the first measurement in step 1, the damper opening rate is changed and the damper performance curve is derived using the measured values of the damper differential pressure and air volume of the terminal unit.

Step 3: Derivation damper position and differential pressure relation formula (see Fig. 4)

At the maximum fan speed measured in the first measurement in step 1, the damper opening rate is changed and the relationship between the damper opening rate and the differential pressure ratio is derived using the measured values of the damper differential pressure and air volume of the terminal unit.

Step 4: Derivation fan speed ratio and maximum differential pressure relationship formula (see Figure 4)

At the minimum damper opening rate measured in the second measurement in step 1 above, the supply fan speed is varied and the measured value of the damper differential pressure of the terminal unit is used to derive a relational expression between the fan speed and the damper differential pressure.

Step 5: Generate virtual air flow sensor at VAV terminal unit (see Fig. 4)

Using the damper performance curve derived from steps 1 to 4, the relationship between the damper opening rate and the differential pressure ratio, and the fan speed and the differential pressure on the damper, a formula for calculating the virtual air volume of the variable air volume terminal unit is derived. Specifically, the virtual air volume of the variable air volume terminal unit is derived using Equations 3 through 10 described above.

Meanwhile, the virtual air volume of the variable air volume terminal unit is calculated through various input variables. However, errors in all input variables may occur in the measuring sensor, and errors in all input variables may affect the calculated flow rate.

Common sensor errors include precision and bias errors. Therefore, the error of the input variable affecting the calculated virtual air flow can be estimated using the Taylor series method, and the uncertainty can be calculated using the following Equation 11. In addition, error types and information of input variables are described in Table 1, and further, parameters used in the equations of the present invention are defined.

(Equation 11)

(여기서, u_Q는 가상 풍량 센서 불확도, α는 변풍량 터미널 유닛 댐퍼 개도율,

는 공급팬 스피드 비, Q는 변풍량 터미널 유닛 풍량, P_dp는 변풍량 터미널 유닛 댐퍼 차압, a_curve, b_curve, c_curve는 성능 곡선 계수)

(where u _Q is the virtual air volume sensor uncertainty, α is the variable air volume terminal unit damper opening rate,

is the supply fan speed ratio, Q is the variable air volume terminal unit air volume, P _dp is the variable air volume terminal unit damper differential pressure, a _curve , b _curve , c _curve is the performance curve coefficient)

<Table 1>

In addition, in order to compare and verify the performance of the virtual air volume sensor with the existing air volume measurement sensor, the relative error is checked using Equation 12 below.

(Equation 12)

(여기서, e는 상대오차, Q_virtual은 가상 풍량, Q_meas는 센서 측정 풍량)

(here, e is relative error, Q _virtual is virtual air volume, Q _meas is sensor measured air volume)

Hereinafter, an embodiment in which the virtual air volume measurement method of the variable air volume terminal unit of the present invention as described above is applied to an actual system will be described.

First, as the test-bed for the verification experiment of the variable air volume terminal unit virtual air volume sensor, a university laboratory where air conditioning experiments are possible was selected. The target air conditioning system (hereinafter, abbreviated as 'target air conditioning system') for the verification experiment supplies heating and cooling to a space of 80 m2, and the configuration diagram of the air conditioning system is as shown in FIG. 5 .

The target air conditioning system consists of a variable air volume terminal unit, an air conditioner, an air-cooled heat pump, and a pump.

In addition, the variable air volume terminal unit used in the target air conditioning system is a type in which a reheat coil is installed, and the design air volume is 1360CMH and the reheat coil heating capacity is 4000kcal.

In addition, the target air conditioning system is equipped with a hot and cold water coil, supply and return fan, and variable air volume control is possible.

In addition, an air-cooled heat pump is used, which supplies cold water to the air conditioner cold water coil, and supplies hot water to the air conditioner hot water coil and the terminal unit reheat coil. The cold and hot water pump can control the flow rate.

In addition, the entire system is monitored and automatically controlled through BAS. In the present invention, as the target air conditioning system, a hot wire anemometer, a differential pressure sensor, a damper actuator, and a supply fan VFD (Variable Frequency Drive, variable frequency drive) were used. Table 2 below shows the specifications of the target air conditioning system used for verification.

<Table 2>

Next, the air volume is virtually measured using the target air conditioning system, but the above-described steps 1 to 5 are sequentially performed.

Step 1: Conduct field measurements to collect damper performance data.

First, at the maximum fan speed, change the damper opening rate of the terminal unit and measure the damper differential pressure and air flow (or wind speed). The measurement results are shown in Table 3.

<Table 3>

Second, after setting the damper opening rate of the terminal unit to the minimum, changing the fan speed and measuring the damper differential pressure and air volume are shown in Table 4.

<Table 4>

Step 2:

At the maximum fan speed of step 1, the damper performance curve is derived using Table 3, which describes the damper differential pressure and air volume of the terminal unit measured while changing the damper opening rate. The derived damper performance curve is as shown in FIG. 6 .

In addition, the derived damper performance curve can be expressed as a quadratic curve, and is calculated by the following calculation using Equation 2 above.

(Calculated using Equation 2)

Step 3:

At the maximum fan speed of step 1, a relational expression between the damper opening rate and the differential pressure ratio is derived using the measured damper differential pressure and air volume of the terminal unit while changing the damper opening rate.

7 is a result of analyzing the relationship between the damper opening rate and the damper differential pressure ratio, and it can be confirmed that a similar tendency is exhibited even in the change of the fan speed, and the correlation coefficient R2 is 0.9964, confirming that the relationship is high.

Accordingly, in order to derive the relational expression between the damper opening rate and the differential pressure ratio, the relational expression was derived using the data measured at the maximum fan speed, as shown in FIG. 8 .

In addition, the damper opening ratio and the differential pressure ratio can be expressed by a cubic equation, and are calculated as follows by Equation 6 described above.

(Calculated using Equation 6)

Step 4:

A relational expression between the fan speed and the damper pressure is derived using the damper differential pressure of the terminal unit as shown in Table 4 measured while changing the fan speed at the minimum damper opening rate in step 1 above.

In this case, the maximum differential pressure according to each fan speed is required to convert the differential pressure ratio in the formula derived in step 3, and for this, a relational expression between the damper differential pressure and the fan speed is derived as shown in FIG. 9 . The relational expression can be expressed as a cubic equation, and is calculated as follows by Equation 8 described above.

(Calculated using Equation 8)

Step 5:

Using the damper performance curve derived from steps 1 to 4, the relationship between the damper opening rate and the differential pressure ratio, and the fan speed and the differential pressure on the damper, a formula for calculating the virtual air volume of the variable air volume terminal unit is derived. Specifically, a formula for calculating the virtual air volume of the variable air volume terminal unit is derived using Equations 3 through 10 described above.

Accordingly, it is possible to derive the virtual V amount calculation equation of the variable air volume terminal unit through steps 1 to 5 as described above, thereby eliminating the need to use a separate air volume sensor. It has the effect of reducing manufacturing cost and improving the accuracy of air flow measurement to secure control stability of the air conditioning system using the variable air volume terminal unit.

Next, the virtual air volume sensor of the variable air volume terminal unit of the present invention calculated as described above was verified.

First, to verify the virtual air volume sensor, data were collected by changing the fan speed and damper opening rate. In addition, fan speed, damper opening rate, and damper differential pressure data were collected through BAS, and the supply air volume was measured using a hot wire anemometer.

In addition, the virtual air volume measurement procedure was applied and the air volume was calculated using Equations 3 and 10, and the uncertainty of the calculated air volume was verified using Equations 11 and 12.

Therefore, the results measured and calculated by the verification method are as shown in Table 5 and FIG. 10 below.

At this time, it can be seen that the uncertainty of the virtual air volume is within ±8.8%, and the uncertainty of the virtual air volume increases as the fan speed and the damper opening rate are lower. And, as a result of comparing the measured air volume and the relative error, the maximum was 5.6%.

<Table 5>

11 shows long-term experimental results of the virtual air volume sensor.

Referring to the drawings, the virtual air volume was continuously measured at 1-minute intervals for 10 hours, and the frequency of the supply fan was operated at 19~21Hz during the experiment period, and the damper opening rate was operated at 59~68.2%. In addition, the damper differential pressure was operated at 88~105Pa.

At this time, the virtual air volume showed a relative error of up to 9.4% with the air volume measured with the hot wire anemometer. It was confirmed that the virtual air volume by the virtual air volume measurement method of the variable air volume terminal unit of the present invention can be effectively applied to the air conditioning system.

Meanwhile, the present invention described above may be embodied in the aspect of a computer-readable recording medium in which a computer program for performing a method for measuring a virtual air volume of a variable air volume terminal unit is recorded.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Claims (10)

A method for measuring a virtual air volume of a variable air volume terminal unit, the method comprising:
Conduct on-site measurement of the variable air volume terminal unit, but at the maximum fan speed, change the damper opening rate of the terminal unit and measure the damper differential pressure and air volume. Step 1 of measuring the damper differential pressure and air volume;
a second step of varying the damper opening rate at the maximum fan speed measured in step 1 and deriving a damper performance curve using the measured values of the damper differential pressure and air volume of the terminal unit;
a third step of varying the damper opening rate at the maximum fan speed measured in the first step and deriving a relational expression between the damper opening rate and the differential pressure ratio using the measured values of the damper differential pressure and air volume of the terminal unit;
a fourth step of varying the supply fan speed at the minimum damper opening rate measured in step 1 and deriving a relational expression between the fan speed and the damper differential pressure using the measured value of the damper differential pressure of the terminal unit; and
Step 5 of deriving a formula for calculating the virtual air volume of the variable air volume terminal unit using the damper performance curve derived from steps 1 to 4, the relational expression between the damper opening rate and the differential pressure ratio, and the fan speed and the damper differential pressure relationship;
A virtual air volume measurement method of the variable air volume terminal unit, characterized in that it comprises a.
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equations 3 and 4 below.
(Equation 3)

(Where, P _dp,f is the differential pressure of the terminal unit damper with variable air volume when the supply fan is at the maximum speed, P _dp,p is the differential pressure of the damper of the terminal unit with the variable air when the partial speed of the supply fan is used.

is the maximum feed fan speed,

is the partial speed of the supply fan, Q _f is the terminal unit air volume when the supply fan is at the maximum speed, Q _p is the air volume of the terminal unit when the supply fan is the partial speed)

(Equation 4)

(Where P _dp,p is the variable air volume terminal unit damper differential pressure at the partial speed of the supply fan, a ₀ , a ₁ , a ₂ are the damper performance curve coefficients, Q _p is the air volume of the terminal unit variable air volume at the partial speed of the supply fan,

is the supply fan speed ratio)
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equation 5 below.
(Equation 5)

(Where P _dp,p is the variable air volume terminal unit damper differential pressure at the partial speed of the supply fan, a ₀ , a ₁ , a ₂ are the damper performance curve coefficients, Q _p is the air volume of the terminal unit variable air volume at the partial speed of the supply fan,

is the supply fan speed ratio)
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equations 6 and 7 below.
(Equation 6)

(Equation 7)

(Where β is the differential pressure ratio of the terminal unit of the variable air volume, b ₀ , b ₁ , and b ₂ are the damper opening degree-differential pressure ratio relation coefficients, and P _dp,p is the differential pressure of the differential pressure of the terminal unit damper at the supply fan partial speed, P _{dp ,max} is the variable air volume terminal unit maximum differential pressure)
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equation 8 below.
(Equation 8)

(Where P _dp,max is the maximum differential pressure of the variable air volume terminal unit,

is the supply fan speed ratio, c ₀ , c ₁ , c ₂ , and c ₃ are the supply fan speed ratio-maximum differential pressure relation coefficient)
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equation 9 below.
(Equation 9)

(where α is the variable air volume terminal unit damper opening rate, β is the variable air volume terminal unit differential pressure ratio, b ₀ , b ₁ , b ₂ is the damper opening degree-differential pressure ratio relationship coefficient, c ₀ , c ₁ , c ₂ , c ₃ is the supply fan speed ratio-maximum differential pressure relation coefficient, P _dp,p is the variable air volume terminal unit damper differential pressure at partial supply fan speed, P _dp,max is the variable air volume terminal unit maximum differential pressure)
The method of claim 1, wherein the virtual air volume in step 5 is derived using Equation 10 below.
(Equation 10)

(Where, Q _p = variable air volume at partial speed of supply fan terminal unit air volume, a ₀ , a ₁ , a ₂ are damper performance curve coefficients, b ₀ , b ₁ , b _{2 ,} b ₃ are damper opening degree-differential pressure ratio relationship coefficient, c ₀ , c ₁ , c ₂ , c ₃ are the supply fan speed ratio-maximum differential pressure relation coefficient, α is the variable air volume terminal unit damper opening rate, Q _p is the air volume when the damper opening rate is p,

is the supply fan speed ratio)
The method of claim 1, wherein the uncertainty in deriving the equation for calculating the virtual air volume in step 5 is calculated using Equation 11 below.
(Equation 11)

(where u _Q is the virtual air volume sensor uncertainty, α is the variable air volume terminal unit damper opening rate,

is the supply fan speed ratio, Q is the variable air volume terminal unit air volume, P _dp is the variable air volume terminal unit damper differential pressure, a _curve , b _curve , c _curve is the performance curve coefficient)
The method according to claim 1, wherein the relative error in deriving the formula for calculating the virtual air volume in step 5 is calculated using Equation 12 below.
(Equation 12)

(here, e is relative error, Q _virtual is virtual air volume, Q _meas is sensor measured air volume)
10. A computer-readable recording medium storing a computer program for performing the method for measuring the virtual air volume of the variable air volume terminal unit according to any one of claims 1 to 9.

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