[0032] Such as figure 1 As shown, this embodiment includes the following steps:
[0033] Step 1. Arrange measuring points in the running air conditioning system, and record the measuring point parameters in real time.
[0034] Such as figure 2 As shown, the arrangement of measuring points refers to the arrangement of compressor discharge temperature measuring points and compressor discharge pressure measuring points between the compressor and condenser of the air conditioning system, and the compressor discharge temperature parameter T 0 And the exhaust pressure parameter p 0; Arrange the temperature measurement point of the liquid pipe at the outlet of the condenser liquid pipe to obtain the liquid pipe temperature parameter T 2; Arrange the compressor suction temperature measuring point and compressor suction pressure measuring point between the evaporator and the compressor, and obtain the suction temperature parameter T of the compressor respectively 1 And the suction pressure parameter p 1; Arrange the return air temperature measurement points of the evaporator fan on the return air side of the evaporator fan to obtain the return air temperature parameter T r.
[0035] An expansion valve is arranged between the condenser and the evaporator.
[0036] The evaporator and condenser are respectively provided with an evaporator fan power meter and a condenser fan power meter to record the evaporator fan power W e And condenser fan power W c.
[0037] Step 2. Perform compressor flow fitting calculation through the compressor flow fitting calculation module according to the parameters obtained in step 1, to obtain the refrigerant flow of the air conditioning system.
[0038] The described compressor flow fitting calculation refers to: using the compressor theoretical calculation formula fitted by the compressor performance parameters, the compressor flow rate at any frequency is converted into a polynomial form about the inlet and outlet pressure and other parameters with the theoretical model. , A series of data points are obtained through the 10-coefficient model provided by the compressor manufacturer, and the coefficients in the polynomial can be fitted to calculate the refrigerant flow rate.
[0039] The compressor is an inverter compressor.
[0040] The refrigerant flow rate m is: Where: C 0 ~C 3 Is the coefficient to be fitted, Is the cylinder volume, v i Is the inspiratory specific volume, f x Is the compressor frequency, p i Is the suction pressure of the compressor.
[0041] The compressor inlet pressure p i , Compressor outlet pressure p o , Cylinder volume Inspiratory specific volume v i And frequency f x A known.
[0042] According to the 10 coefficient formula obtained from the standard test experiment of the compressor, a series of flow data at different evaporating temperature, condensing temperature and frequency can be obtained. According to the above formula, the least square method can be fitted to obtain C 0 ~C 3.
[0043] Step 3. Combining the theory of refrigeration cycle, the cooling capacity of the air conditioning system, the heat exchange of the condenser, the compressor power and the EER (energy efficiency ratio) are calculated through the two-unit calculation module.
[0044] The refrigeration cycle theory refers to the calculation of the heat exchange on the refrigerant side of the air conditioning system (that is, the theoretical refrigeration capacity) according to the refrigerant flow rate and the enthalpy value at the inlet and outlet of the evaporator, and the heat exchange of the condenser is calculated in the same way. In this case, heat loss needs to be considered before calculating the actual cooling capacity; due to the energy conservation of the air conditioning system, the actual power of the compressor can be calculated according to the actual cooling capacity, condenser heat exchange and heat loss to obtain the real-time EER of the air conditioning system.
[0045] This embodiment is a special case, that is, the compressor is arranged near the evaporator, and the compressor will dissipate part of the cold energy on the air side of the evaporator.
[0046] The said refrigerant side heat exchange Q eva For: Q eva =m×(h 1 -h 4 ), where: h 1 Is the enthalpy value of the evaporator outlet, h 4 Is the enthalpy value of the evaporator inlet.
[0047] Such as image 3 As shown, point A is the evaporator outlet, point B is the condenser inlet, point C is the condenser outlet, point D is the evaporator inlet, and the corresponding enthalpy values are respectively h 1 , H 2 , H 3 And h 4.
[0048] According to the physical property calculation formula, the temperature and pressure of a point can be used to calculate the enthalpy value of that point. And the pressure p at point A and point B 1 , P 2 And temperature T 1 , T 2 Known, the enthalpy h of point A and point B can be obtained 1 , H 2; Temperature T at point C 3 It is known that the pressure at point C is the same as that at point B, and the enthalpy value of point D is h 4 Same as point C.
[0049] The amount of heat exchange on the refrigerant side obtained from the above equation is the theoretical cooling capacity, and the heat loss caused by the heat exchange between the compressor next to the evaporator and the surrounding air needs to be considered. Therefore, the theoretical cooling capacity is corrected to obtain the actual cooling capacity.
[0050] The actual cooling capacity is: Q real =Q eva -Q loss , Where: Q loss Is the heat loss (dissipated amount).
[0051] Said heat loss Q loss for: Among them: h is the heat transfer coefficient, d is the outer diameter of the compressor, L is the length of the compressor, R is the fan opening (%), R bass Is the reference opening of the fan during the test, T r Is the return air temperature of the evaporator.
[0052] The heat transfer coefficient h is usually 50.
[0053] The fan opening R is directly read out by the fan meter.
[0054] The said condenser heat exchange Q cond For: Q cond =m×(h 2 (p 2 ,T 2 )-h 3 (p 2 ,T 3 )).
[0055] The actual power of the compressor can be analyzed and calculated by the energy conservation of the air conditioning system.
[0056] The actual power of the compressor is: W real =W ceff +Q loss , Where: W real Is the actual compressor power, W ceff Is the theoretical power of the compressor, W ceff =Q cond -Q eva.
[0057] The energy efficiency ratio is:
[0058] Step 4. Based on the fan performance curve and the fan resistance-heat exchanger characteristic equation, the air volume of the indoor and outdoor units is calculated through the fan calculation module to realize the online detection of the air conditioning system performance.
[0059] The calculation based on the fan performance curve and the fan resistance-heat exchanger characteristic equation means: According to the fan performance curve relationship (Pq-Power) provided by the fan manufacturer, the pressure drop and air volume of the fan at a given power can be obtained The first relationship; combining the air-side resistance characteristic equation of the heat exchanger (condenser and evaporator) and the relationship between air volume and wind speed, the second relationship between the pressure drop on the air side of the heat exchanger and the air volume can be obtained; two Relations are solved simultaneously to obtain the air volume and pressure drop at a given fan power.
[0060] The fan performance curve is: ΔP=f(q,P), where: ΔP is the pressure drop, q is the air volume, and P is the fan power.
[0061] The derivation process of the second relationship is as follows: the air-side pressure drop of the indoor and outdoor units of the air conditioning system has a quadratic relationship with the wind speed, and there is a linear relationship between the wind speed and the air volume, namely: Among them: g is the acceleration due to gravity, A is the area of the windward side of the heat exchanger, L and d are the inherent (known) parameters of the heat exchanger. Substituting the test operating point data of the heat exchanger and the relationship between wind speed and air volume, we can get: ΔP=kq 2 , Where: k is the resistance characteristic coefficient of the heat exchanger, that is, the product of all constant terms.
[0062] The air volume q and pressure drop ΔP under a given fan power are: When the fan power P is known, the simultaneous equation is a two-dimensional quadratic equation, which can be solved to obtain the only real root of pressure drop and air volume.
[0063] There is a linear relationship between the fan power P and the fan opening R, namely: P=aR+b, where a and b are coefficients to be fitted.
[0064] The relationship between the fan opening R and the pressure drop ΔP is: ΔP=f(R).
[0065] The relationship between the fan opening R and the air volume q is: q=f(R).
[0066] The above specific implementations can be locally adjusted by those skilled in the art in different ways without departing from the principle and purpose of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific implementations. All implementation schemes within the scope are bound by the present invention.
