RU1778364C - Stand for testing refrigerant compressors - Google Patents

Abstract

The invention relates to testing means for refrigeration compressors. The purpose of the invention is to increase the reliability of the results and reduce the time and energy costs of testing. The test bench contains a compressor under test, a condenser with a refrigerant vapor cooler, a throttle valve on the liquid refrigerant line, a condenser with a heater that compensates for the heat load on the evaporator, the heater and cooler being made in the form of thermoelectric batteries powered by an independent electric source, and it also contains heat exchangers connected in series into the circulation circuit of the cooling medium, 1 ill.

Description

The invention relates to refrigeration, in particular to means for testing refrigeration compressors, and can be used to create new compressor designs and improve existing ones.

The aim of the invention is to increase the reliability of the results and reduce the time and energy costs of testing by ensuring the accuracy of maintaining thermal conditions.

The drawing shows a diagram of a bench for testing refrigeration compressors.

The test bench contains a test compressor 1 connected in series to a closed circuit through pipelines, a condenser with a refrigerant vapor cooler 2, a throttle valve 3 on the liquid refrigerant line, and a calorimeter with a heater 4 that compensates for the heat load on the evaporator. The cooler 2 is made in the form of a thermoelectric battery (TEB) 5, the cold layer 6 of which is in thermal contact with the condenser 7, and the hot layer 8 is in thermal contact with the heating heat exchanger 9.

The cooler 2 is enclosed in thermal insulation 10. Thermocouples 11 and 12 are placed on the thermopile layers 5. In addition, thermocouples 13 and 14 and pressure gauges 15 and 16, respectively, are located at the inlet and outlet of the condenser 7.

The heater 4 is made in the form of a thermoelectric battery (TEB) 17, the hot layer 18 of which is in thermal contact with the calorimeter 19, and the cold layer 20 is in thermal contact with the cooling heat exchanger 21. The heater 4 is enclosed in thermal insulation 22. On the layers of the thermopile 17, thermocouples 23 and 24 are placed. In addition, a thermocouple 25 is placed in the calorimeter 19. At the outlet of the calorimeter 19, a thermocouple 26 and a pressure gauge 27 are placed.

The cooler 2 is equipped with shut-off valves 28 and 29, and the heater 4 is equipped with shut-off valves 30 and 31.

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The heat exchangers for heating 9 and cooling 21 are successively connected to the circulation circuit of the cooling medium 32.

Before testing, the test bench is evacuated and charged with a refrigerant. The effect of heat exchange with the environment is taken into account by determining the product of the heat transfer coefficient and the surface area of the heat exchange unit (KF) with the difference between the temperatures of the refrigerant and the environment At 10.20.30 ° C. Thus, for cooler 2 - (KF) is determined as follows. A portion of the condenser 7 is filled with a liquid refrigerant. To do this, turn on compressor 1 and simultaneously supply power to TEB 5 in such a way as to ensure condensation of the refrigerant in the condenser 7. After partially filling the condenser 7, stop the compressor 1 and turn off the valves 28 and 29. Upon reaching the temperature equilibrium between the refrigerant in the condenser 7 and the environment supplies the thermopile 5 with a polarity such that heat is released on the cold spas 6 of the thermopile 5. The amount of heat generated must be such as to maintain a temperature difference between the temperature of the refrigerant (determined by the saturation pressure of pressure gauges 15 and 16) and the ambient temperature of 10.20.30 ° C in stationary mode. Using the known ratios, depending on the amount of current supplying the thermopile thermopile 5, the amount of heat released on spas is determined. Then:

(KF) KA,

where OSP is the amount of heat released at the spa x, W;

t tx.a. - tcp is the temperature difference of the refrigerant and the environment, ° C.

The determination of (KF) for heater 4 is carried out similarly to the determination of (KF) for cooler. A distinctive feature of the determination of (KF-) for a calorimeter is that in the calorimeter 19, the refrigerant is cooled in the cold junctions 18 of the thermopile 17.

At the time of testing, valves 30 and 31 are closed, compressor 1 is turned off. The calculation of the amount of heat removed is carried out according to

(KF) K Qcn (Aty1,

where OSP is the amount of heat allocated to the spa x from the refrigerant, W;

At tcp - tx.a., ° C - difference in ambient temperature and refrigerant. Stand operation in compressor calorimetry mode.

Compressor cooling capacity is determined in accordance with regulatory documents in the standard mode, depending on the respective compressor design.

0 The stand in the calorimetric mode of the compressor operates as follows.

Simultaneously with the compressor 1 on, power is supplied from stabilized DC sources (conventionally not shown in the stand diagram) to thermoelectric batteries 5 and 17. In this case, the temperature of cold junctions 6 thermoelectric 5 and 20 thermoelectric 17 decreases, and the temperature of hot junctions 8 and 18 of the corresponding thermopiles are increased.

In the condenser 7, condensation of the refrigerant occurs due to heat removal by cold junctions 6 of the thermopile 5, and

In calorimeter 5, the refrigerant is boiled by supplying heat from the hot junctions 18 of the thermopile 17.

The temperature of the cold junctions 6 of the thermopile 5 is maintained at a temperature level sufficient to ensure complete condensation of the refrigerant vapor. The condensed refrigerant through the control valve 3 enters the heat exchanger 19. In the control valve 5, the refrigerant pressure drops to a predetermined boiling pressure.

The temperature of the hot junctions 18 of the thermoelectric battery 17 is set so as to ensure full boiling

0 liquid preset superheat of refrigerant vapor before suction into compressor 1.

Heat removal from hot junctions 8 of thermopile 5 is carried out in a heat exchanger

5 9 through a cooling medium such as water or air. In the cooling heat exchanger 21, heat is supplied from the environment (air, water).

Upon the onset of the stationary thermal regime under the conditions of constant pressure of condensation and boiling, the compressor refrigerating capacity is determined. The value required for the calculation of cooling capacity,

5 is the flow rate of a refrigerant.

The flow rate of the refrigerant in the bench is determined in two independent ways:

on the thermal balance of the condenser; on the thermal balance of the calorimeter.

Determination of refrigerant consumption by the heat balance of the condenser.

The flow rate of the refrigerant is determined from the ratio:

Ge QK (lA-iB) 1, where QK is the amount of condensation heat. Tue

1d - enthalpy of the refrigerant at the inlet to the condenser, kJ / kg;

in - enthalpy of the refrigerant at the outlet of the condenser, kJ / kg,

QK Osp + OKD.

where OSP is the amount of heat determined in accordance with the current supplying the thermoelectric battery 5, W;

OKD - heat loss from a condensing refrigerant, W.

The enthalpies of the refrigerant at the inlet and outlet of the condenser are determined by temperature and pressure using thermocouples 13 and 14, as well as manometers 15 and 16. The current supplying the thermopile 5 is measured using an ammeter (not shown conventionally in the diagram).

An alternative method for determining the amount of heat removed from a condensing refrigerant is by using the Seebeck effect. The thermoelectric battery 5, which has reached the stationary thermal mode, is instantly, during the measurement, switched to the thermoelectric power generation mode by switching off the current supplying the thermopile 5. At the same time as measuring the thermopower, the temperature of the cold and hot junctions of the thermopile is measured 5. The amount of heat removed from the condensing refrigerant proportional to the value of the obtained thermopower.

The flow rate of the refrigerant according to this method is determined by the above method.

Thus, the flow rate of the refrigerant according to the heat balance of the condenser can be determined by two methods, which will improve the accuracy of the determined value.

The flow rate of the refrigerant from the heat balance of the calorimeter is determined in the same way as for a condenser.

Next, the calculation of the compressor cooling capacity is carried out according to known methods.

The work of the stand in the gas ring mode.

Compressor testing according to this test bench design can also take place in the gas ring mode. In this case, the thermopile 5 will only cool the flow of gaseous refrigerant in the condenser 7. Condensation of the refrigerant

will not be. The throttled refrigerant will be heated in the heat exchanger 19 of the fuel cell 17. The maintenance of the compressor test mode in the gas ring 5 is provided by the current supplying the fuel cells 5 and 17.

When tested in the calorimetric modes of the compressor and the gas ring, heat is removed from hot junctions 8 of thermoelectric cooler 5 and

0 cold junctions 20 TEB 17 is carried out into the environment, respectively, in heat exchangers 9 and 21. In this case, the cooling medium passing through the heat exchanger 21 and cooled therein is fed to the inlet

5 heat exchanger 9.

The stand operates in the mode of creating dynamic loads on the compressor movement mechanism.

To reduce test time,

0 i.e. in order to intensify the processes causing an increase in the wear rates of parts and components of the compressor, the compressors are tested in start-stop cycles. At the same time, the duration of the operation of the friction during transient lubrication, i.e. in conditions of boundary and semi-dry friction. Boundary and especially semi-dry friction is accompanied by an increase in the mating temperature and its

0 increased wear. Boundary friction takes place at the start-stop moments of a refrigeration compressor, i.e. during periods of unstable operation of their interfaces, as well as during a sharp change in the forces acting in them.

Unstable operation of the interfaces is also characteristic in the case of a quick transition from one compressor test mode to another. Such a transition reaches 0 s by changing the magnitude of the current supplying the thermopile elements 5 and 17 according to a certain program.

Claims (1)

Claim 5 Test bench for refrigeration compressors comprising a test compressor in series with a circuit, a condenser with a refrigerant vapor cooler, a throttle valve on line 0 of the liquid refrigerant and a calorimeter with a heater that compensates for the heat load on the evaporator, and that in order to increase the reliability of the obtained results and reduce the time and energy costs for testing by ensuring the accuracy of maintaining thermal conditions, the cooler and heater l are made in the form of thermoelectric batteries supplied by independent electric power sources, the cold junction of the cooler and the hot junction are heated by flow heat exchangers the watermelons are installed in thermal contact with and cooling, sequentially turning on cooling, sequentially connected by a condenser and calorimeter corresponding to the cooling circuit, and their opposite junctions supply the medium.  flow heat exchangers and cooling, sequentially included in the circulation circuit of the cooling medium. 28 Z 11 7 6 U / J