The method for determining the parameters of the compression refrigerating machine

 

(57) Abstract:

The invention relates to refrigeration, and in particular to household refrigerators compression-type. The method for determining the parameters of the compression refrigerating machine is done by using the criteria of similarity of operation of separate subsystems refrigeration equipment, measurement diagnostic parameters without using special stands and means of measurement. The use of the invention will improve the accuracy of the information, and to broaden the search parameters of the refrigeration machines of the compression type when determining their actual values, as well as to unify the tools. 1 C.p. f-crystals.

The invention relates to refrigeration, and in particular to household refrigerators compression-type.

Known methods of testing household refrigeration compression type used at the stages of its manufacture, as a final operation after the repair, the process control of technical condition during operation [GOST 17008-85]. [1].

The main disadvantage of the used methods is the lack of depth diagnostics, which allows the individual elements. The presence and nature of the existing defects in HM without its disassembly and subsequent defecation assemblies, and components to identify possible only with a certain probability.

The closest in technical essence is a method for determining the cooling capacity of the compressor compression household HMM [GOST 17008-85] , which consists in measuring the working parameter (cooling capacity) by using the calorimetric stand. At the stand of the register values of the parameters: the pressure of the refrigerant, the atmospheric pressure, the temperature of the refrigerant and water temperatures, water flow rate.

These values are then substituted in the calculation of the dependence that the calculated weight of the compressor on the heat balance calorimeter, the weight capacity of the compressor according to energy balance of the condenser, the actual weight of the compressor. The value of the enthalpy of the refrigerant, a member of the calculated dependences determine thermal charts i=lgP.

The disadvantages of this method are

- the need to measure parameters, implement the method of the special stand;

- the need for special diagramlite the discrepancy between the actual values of the parameters of their normative values and quantify this reason (for example, the amount of wear in the cylinder-piston group-motor-compressor).

The aim of the present invention is to improve the accuracy, informativeness, and the expansion of the unknown parameters HMMM compression type when determining their actual values, as well as the unification of the ways and means.

The invention consists in that when determining the parameters of the HMM, we present a set of subsystems that uses expressions in the form of criteria of similarity of function, composed of measured, a priori known and unknown parameters

< / BR>
wherei- the similarity criterion;

Yi- search option;

Xj- measured parameters;

Ztowell - known options;

that is, the exponents of the parameters.

First, substituting in criteria expression regulatory corresponding to the operational state of the system-analog measured values (temperature, pressure halon), search (for example capacity, the gap in the cylinder-piston group, etc.,) and a priori known parameters (heat capacity, density, halon, etc) HMM, I hope the normative values of criteria of similarity:i- Crete is the palm) HMM. Normative values of criteria of similarity constant values, P= idem, after substitution in criteria expression measured and a priori known parameters, calculate the values of desired parameters.

The criteria expression when this is compiled from the subsystem parameters (input, output, internal, structural, and so on) with a mutual physical or functional relationship that distinguishes the proposed method from the known. Through the use of multiple links, that is, the principle of the system approach increases the accuracy and objectivity in the determination of the desired parameters regardless of the purpose of their definition.

Example: to Determine the cooling capacity of the CHILLER type "Nord-214-1" after its repair. Based on the proposed method, the problem is solved as follows.

1. Refrigerating machine Nord-214-1" appears in the form of a complex system with subsystems: compressor, condenser, evaporator", "capillary tube", "filter drainage Chuck" and so on

2. For each of the subsystems define the set of output, input, internal parameters; set the functional dependence of the output characteristics, such as holodoproizvoditelnost bullet dimensions, criteria based, reflecting the similarity of the operation of subsystems HMM.

4. Choose the similarity criteria of one of the subsystems HMM, on measured parameter, for example the subsystem "evaporator" cooling capacity. In this case, this criterion is

(1)

where tu= t-t - the temperature difference between the air in the evaporator;

tn, tto- air temperature, respectively at the beginning and at the end of the transition process in the initial period of operation of the CHILLER (from launch to the first actuation of thermostat);

Cu= Cn-Cto- the difference between heat capacities of the air in the evaporator;

CnCto- heat capacity of air at the beginning and at the end of the transition process;

Vand- the total volume of the evaporator;

andis the coefficient of thermal diffusivity of the wall of the evaporator;

Q - cooling capacity compressor CHILLER;

the time of the transition process in the initial period of operation of the CHILLER;

and- coefficient of thermal conductivity of the wall of the evaporator.

The normative value of the similarity criterionQcalculate the target values included in the expression (1) options (as is done, for example, when standard factory tests). For the CHILLER compressor is equal toQ= 0,710-3.

5. Refrigerating machine (Nord-214-1") equip (according to GOST 16317-E) sensors, in this case, the temperature sensor in the evaporator.

6. Include HMMM.

7. In the process, HMM produce registration parameter values.

In this case, obtained the following values of parameters:

tn= K, tto= K, tand= 44K; = 4424 S.

8. Take known values

- the total volume of the evaporator;

coefficients of thermal diffusivity and thermal conductivity of the wall of the evaporator.

Values of heat capacities of air is determined by the "thermodynamic tables for dry air".

In this case, these parameters are the following:

Cn= 393 j/(m3K);

Cto= 187 j/(m3K);

Cand= 206 j/(m3K);

Vand= 0.20 m3;

and= 0.25 m2;

and= 169 W/(MK).

9. Substituting from expression (1), the equation for

(2)

the values of the parameters specified in PP 7, 8 andQ,determine the actual value of the cooling capacity. In this case, a value of Qd= 178,38 watts.

10. Compare the actual value of the cold is the line. In this case, the degree of mismatch is equal to

< / BR>
what is acceptable according to GOST 17008-85.

Therefore, repair HMM done.

The example clearly illustrates the essence of the proposed method and the possibility of the use in the diagnosis of technical condition of the CHILLER. When this criterion is to be evaluated appropriate goal parameters (gap in cylinder-piston group-motor-compressor and other)

Literature

1. Compressors hladikova sealed. General specifications GOST 17008-85. Standards publishing house, 1989

1. The method for determining the parameters of the refrigeration machine, for example, compression-type, which consists in the fact that they measure the diagnostic parameters: air temperature in the evaporator, the pressure of the refrigerant, and the values of the desired parameters of the refrigeration machine determined indirectly by subtracting the results of direct measurements of these and other a priori known parameters calculated according to, characterized in that to increase the accuracy, informativeness and enlargement of unknown parameters when determining their actual values, as well as the unification of item refrigerating machine, composed of measured, a priori known and unknown parameters:

< / BR>
wherei- the similarity criterion;

Yi- search option;

Xj- measured parameters;

Zkwell - known options;

that is, the exponents of the parameters,

calculated values of similarity criteria for normative values of all parameters included in criteria expression that is registered under the specified mode of operation of the refrigeration machine measured parameters, such as temperature, pressure of the refrigerant, and, substituting in the expression of the normative values of criteria of similarity, measured and known a priori parameter values, calculate the values of desired parameters of the refrigeration machine.

2. The method according to p. 1, characterized in that to control the technical condition of the refrigeration machine as normative values of the parameters take the values corresponding to the operational state, and the calculated values of desired parameters is compared with preset and make a conclusion about the actual technical condition of the refrigeration machine.

 

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