JP2008281255A - Refrigerant flow rate measuring method, method of obtaining cooling/heating capacity of refrigerating device, and refrigerant flow rate measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a flow rate of a refrigerant circulated in a compression-type refrigerating cycle by an ultrasonic flowmeter, without affecting an ordinary operation. <P>SOLUTION: In a pipe 3 in which the liquefied refrigerant from a condenser 5 of an outdoor unit 1 flows, the refrigerant of a gas and liquid two phase state is cooled to a liquid phase state (flooded state) by a cooling device 41. A flow rate of the refrigerant in the liquid phase state, is measured by transducers 32, 33 of the ultrasonic flowmeter 31. As bubbles are not mixed in the liquid phase state, the measurement can be accurately performed. The refrigerant after the measurement is heated to the gas-liquid two phase state before the cooling, by a heating device 41. As the refrigerant is kept in the gas and liquid two phase state again after the measurement, the measurement of the refrigerant flow rate can be accurately performed without affecting the ordinary operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for measuring a refrigerant flow rate, a method for obtaining cooling / heating capacity of a refrigeration apparatus such as a refrigerator, and a refrigerant flow measurement apparatus, and in particular, cooling in an evaporative compression refrigeration cycle such as a multi air conditioning system for buildings. Since the capacity and heating capacity are measured, it is suitable for measuring the flow rate of the refrigerant with high accuracy without any trouble in the operation of the facility.

  Multi air conditioning systems for buildings are used in about 70% of commercial building air conditioning systems because of their low cost, design and construction, individual control, and ease of operation. Recently, the market has been expanded to large-scale buildings with the progress of large capacity and energy saving. After the revision of the so-called Energy Conservation Law, customer demand for the performance evaluation of existing facilities in an operating building has been strengthened for energy conservation measures, but it is difficult to measure the heating and cooling capacity of multi-air conditioning systems for buildings locally. The reason for this may be a measurement method from the refrigerant side using the refrigerant flow rate and refrigerant state (enthalpy) as one method of capacity measurement. This is because there is no method that can be reliably measured.

  Multi-air conditioning systems for buildings have a large number of indoor units (1 to several indoor units for each outdoor unit) and are installed in living rooms (such as guest rooms and business spaces). Because there are many, measurement with an outdoor unit is being studied.

  A compressor curve method has been proposed as one method for estimating the cooling and heating capacity by measuring with an outdoor unit. This is to estimate the refrigerant flow rate in the refrigeration cycle using the refrigerant state (refrigerant temperature and pressure) at the compressor inlet, the compressor frequency, and the operation characteristic data of the representative tester owned by the manufacturer. And it is the method of estimating an air-conditioning capability using the enthalpy in each state point in a refrigerating cycle to this refrigerant | coolant flow rate.

  However, this method is an estimation method for only a specific manufacturer's product, and further lacks in versatility because there are restrictions on new and old systems. In addition, due to individual differences in manufacturing and installation of equipment, performance measurement accuracy is also lacking.

  By the way, in the evaporative compression refrigeration cycle, the cooling capacity is obtained by multiplying the refrigerant inlet / outlet enthalpy difference, and the heating capacity is obtained by multiplying the condenser inlet / outlet enthalpy difference by the refrigerant flow rate. When actually measuring the cooling / heating capacity from the refrigerant side of the outdoor unit in the refrigeration cycle, it is necessary to measure the flow rate of the refrigerant flowing through the pipe (liquid pipe).

  In such a case, since the electromagnetic flow meter cannot be used because the refrigerant is non-conductive, a Coriolis type mass flow meter is used. However, since the mass flow meter is installed in the pipeline, the equipment must be stopped and the piping must be cut. Furthermore, since operations such as extracting and injecting refrigerant also occur, it is difficult to implement in a building in actual operation.

  In general, there is a method using an ultrasonic flowmeter to measure the flow rate from the outer surface of the pipe without cutting the pipe in the building in operation, and the cold / hot water pipe for air conditioning that has a diameter of 20A (outer diameter of about 20 mm) or more. In, a propagation time difference type ultrasonic flowmeter can be used. Also, commercially available ultrasonic flowmeters exist for thin pipes having an outer diameter of about 6 mm, such as refrigerant pipes (liquid pipes).

  And it was proposed to measure a refrigerant | coolant flow volume with an ultrasonic flowmeter, and to perform capacity | capacitance measurement with the measurement of a refrigerant | coolant state (patent document 1). However, the ultrasonic flowmeter cannot accurately measure the flow rate if bubbles are present in the pipe. This is because air bubbles flow along with the liquid in the pipe to prevent the propagation of ultrasonic waves in the pipe, and the signal reception intensity cannot be obtained, making measurement impossible. The Doppler type ultrasonic flowmeter measures the amount of change in the flow velocity from the deviation of the frequency of the reflected ultrasonic waves that bounce off the bubbles and fine particles that flow with the fluid, and is the standard for measuring the absolute value of the flow rate. Therefore, it cannot be applied as it is. That is, a reference flow meter must be provided separately.

  On the other hand, when measuring the flow rate of refrigerant and liquefied gas, which is easy to vaporize and consequently gas-liquid two-phase, we also propose a technology that suppresses vaporization by cooling these refrigerant and liquefied gas before measuring the flow rate (Patent Documents 2 and 3).

JP 2006-183953 A JP-A-57-35773 Japanese Utility Model Publication No. 62-37397

  However, since Patent Document 2 relates to liquefied gas of fuel system such as LPG and LNG, and these are used as gas fuel after that, after measuring the flow rate in the liquid phase stage, it is then vaporized. There was no problem even if it was in the gas phase, so there was no provision or need for treatment after measuring the flow rate. On the other hand, also in Patent Document 2, the target refrigerant is a refrigerant for cooling an electric power cable, and after measuring by suppressing the vaporization of the flow rate of the refrigerant, the cooling capacity itself is determined no matter what the refrigerant is thereafter. It is not a problem if it is provided, and therefore there is no disclosure about the treatment after measuring the flow rate.

  With the techniques of Patent Documents 2 and 3 described above, it is not possible to measure the flow rate of refrigerant in a refrigeration apparatus having a compression refrigeration cycle. This is because if the refrigerant is cooled and then circulated in the liquid phase, the operation may be hindered or the original ability may not be exhibited. For example, if the technique disclosed in Patent Document 2 is applied to a refrigeration cycle and the refrigerant is circulated as it is after cooling, the capacity becomes excessive and normal operation is not achieved. According to the knowledge of the inventors, it is considered that an error of 20% occurs. Therefore, even if the refrigerant in such a refrigeration cycle is measured, the original capacity cannot be measured correctly. Similarly, as in the technique of Patent Document 3, even if it is bypassed after cooling and gas-liquid two-phase is made, it is difficult to reproduce the normal operation state, and not only correct measurement cannot be performed, but also the operation itself is hindered. There is a risk of it coming.

  This will be described in more detail. FIG. 13 shows a normal cycle of a vapor compression refrigeration apparatus having a condenser, an expansion valve, a compressor, and an evaporator, and a refrigerant cycle (Mollier diagram) when cooling is applied. In this figure, when the refrigerant discharged from the condenser is cooled, the refrigerant state on the expansion side changes (the enthalpy decreases). Thereby, the enthalpy difference (refrigeration effect) on the evaporation side is expanded. Therefore, the difference from the enthalpy h1 when the refrigerant is cooled is greater than the enthalpy h0 during normal operation. Moreover, since the inside of the pipe from the outdoor unit to the expansion valve of the indoor unit is in a liquid state, the pressure loss of the refrigerant liquid pipe is reduced. For these reasons, the operating state to be measured changes to the side where the device performance is improved. In addition, due to the expansion of the refrigeration effect, when the load is constant, the number of times of starting and stopping the compressor increases or the refrigerant flow rate decreases, resulting in a difference from the actual performance.

  From the above, after all, for outdoor units of multi-air conditioning systems for buildings, the liquid pipe of the outdoor unit (the piping through which the refrigerant flows after liquefaction) can be used for manufacturers, models, operating conditions, and outdoor conditions. However, since there is a fact that air bubbles are mixed, it is difficult to measure the refrigerant flow rate of the multi-air conditioning system for buildings with the above-described conventional technologies.

  The present invention has been made in view of the above points, and even if the refrigerant circulates under the vapor compression refrigeration cycle, the flow rate thereof can be measured with an ultrasonic flowmeter and is appropriate even after the measurement. The purpose is to prevent the operation of equipment using the refrigeration cycle from being hindered.

  In order to achieve the above object, the present invention is a method for measuring the flow rate of a refrigerant circulating under a vapor compression refrigeration cycle, in a gas-liquid two-phase state in a pipe through which the refrigerant after being liquefied in the refrigeration cycle flows. The refrigerant is cooled to a liquid phase state, and the flow rate of the refrigerant after being in the liquid phase state is measured by an ultrasonic flowmeter, and the refrigerant after the measurement is finished in a gas-liquid two-phase state before cooling. It is characterized by heating up to.

  According to the present invention, in the pipe through which the refrigerant after liquefaction in the refrigeration cycle flows, the refrigerant in the gas-liquid two-phase state is cooled to the liquid phase state, that is, the full liquid state in which the inside of the pipe is filled with the liquid. Since the refrigerant flow rate is measured with an ultrasonic flowmeter, the refrigerant in the full liquid state has almost no bubbles, and as shown in the experimental example described later, the refrigerant flow rate (volume flow rate) is accurately measured. ) Can be measured. Since the refrigerant after the measurement is heated to the gas-liquid two-phase state before cooling, the operation capacity of the refrigeration cycle is not affected and the operation is not hindered.

  This will be described with reference to FIG. 1. FIG. 1 shows a refrigerant cycle (Mollier diagram) in the case where the refrigerant is cooled and then heated to return the refrigerant state to the gas-liquid two-phase state. The refrigerant is cooled to a liquid phase state (full liquid). Then, after the flow rate is measured in the full liquid state, the refrigerant is heated to a heat amount equal to or higher than the cooled amount of heat to return the refrigerant state to the gas-liquid two-phase state. As a result, the flow rate can be measured by the ultrasonic flowmeter without greatly changing the operating state of the refrigeration cycle. If the heating amount is excessively increased with respect to the cooling heat amount, the gas phase of the liquid pipe increases and the pressure loss increases, so that the operating efficiency may be lowered (change in operating state). If the amount of heat of cooling is made too large relative to the amount of heating, the refrigerant that was originally flowing in the liquid pipe in the gas-liquid two-phase becomes a liquid phase and supercooled state, so the pressure loss of the liquid pipe is reduced and the refrigeration effect is increased. Therefore, since improvement in operating efficiency (a large change in the operating state) can be considered, it is preferable that the cooling heat amount and the heating amount of the refrigerant are equal, and at this time, it is possible to measure the driving performance with the highest accuracy.

  Note that whether or not the refrigerant in the gas-liquid two-phase state has cooled to a full liquid state that fills the inside of the pipe with the liquid may be performed as follows, for example.

First, it can be predicted from how the indicated value of the ultrasonic flowmeter fluctuates. That is, (1) In the case of the liquid phase, the fluctuation of the indicated value is small and stable, but in the case of the gas-liquid two phase, the indicated value greatly fluctuates in an early cycle or an abnormal value (for example, unthinkable Large or negative value) is output.
(2) Compare the refrigerant enthalpy calculated from the temperature of the refrigerant measured upstream of the measurement section (downstream of the part being cooled) and the pressure measured by the outdoor unit, and the saturated liquid enthalpy at the pressure measured by the outdoor unit. The refrigerant enthalpy is lower than the saturated liquid enthalpy, i.e.
Enthalpy obtained from measured values of refrigerant temperature and pressure <saturated liquid enthalpy at the measured pressure,
If the above condition is satisfied, it can be confirmed that the liquid has been formed.
(3) The temperature is basically the same even when temperature is used.
That is, the refrigerant temperature measured upstream of the measurement section (downstream of the part being cooled) is compared with the saturated liquid temperature at the pressure measured by the outdoor unit, and the refrigerant temperature is lower than the saturated liquid temperature,
If the condition of the measured temperature of the refrigerant <the temperature of the saturated liquid at the measured pressure is satisfied, it can be confirmed that the liquid has been formed.
In the above case, the pressure can be measured using maintenance tapping. The refrigerant temperature can be measured from the surface temperature of the pipe.

  Although it is conceivable that the refrigerant does not turn into a liquid phase due to mixing of moisture and impurities, such a case can be dealt with by further cooling. For example, the inventors may consider the amount of cooling heat that can be cooled to about “saturated liquid temperature −5 K” at the rated refrigerant flow rate. As will be described later, when the pipe length from the outdoor unit to the measurement section is long, from the saturated liquid temperature at the pressure obtained by subtracting the pressure loss (estimated value) of the pipe (liquid pipe) from the outdoor unit outlet pressure to the measurement section, It is considered that the amount of cooling heat may be further reduced by about 5K.

Based on the refrigerant flow rate thus measured, the cooling / heating capacity of the refrigeration apparatus using the vapor compression refrigeration cycle can be obtained. That is,
Cooling / heating capacity: A [kW]
Refrigerant flow rate: F [L / h]
Specific gravity of refrigerant: S [kg / L]
Gas refrigerant enthalpy: GP [kJ / kg]
Liquid refrigerant enthalpy: LP [kJ / kg]
Power consumption of refrigeration equipment: W [kW]
Heating amount when the refrigerant is heated: H [kW]
Heat of cooling when the refrigerant is cooled: C [kW]
In this case, the cooling / heating capacity of the refrigeration apparatus can be obtained by the following equation.
A = F * S / 3600 [sec / h] * {(GP-LP)-(HC) / (F * S / 3600 [sec / h])}

  In addition, the coefficient of performance (COP) of the said refrigeration apparatus can be calculated | required by remove | dividing the air-conditioning capacity calculated | required in this way by the power consumption of a refrigeration apparatus.

  By the way, in the capacity measurement in the outdoor unit, when the indoor unit functions as a cooling unit, as shown in FIG. 2, the piping 3 from the outdoor unit 1 to the indoor unit 2 and the piping returning from the indoor unit 2 to the outdoor unit 1. Due to the heat loss at 4, the difference occurs as compared with the case of measuring with the indoor unit 2 side refrigerant. However, when the pipe 3 is a liquid pipe, the influence is small because the pipe 3 is thin and has a small pipe diameter and the refrigerant temperature is relatively close to the environmental temperature. In this example, the outdoor unit 1 is provided with a condenser 5 and a compressor 6, while the indoor unit 2 functions as an evaporator. When the refrigerant enthalpy is calculated by the outdoor unit 1, the thermometer 11 and pressure gauge 12 provided at the location on the outdoor unit 1 side in the pipe 3, the thermometer 13 provided at the location on the outdoor unit 1 side in the pipe 4, pressure A total of 14 measurement results are used. Therefore, the outdoor unit 1 side refrigerant enthalpy 21 when the pipe 3 functions as a liquid pipe, the outdoor unit 1 side refrigerant enthalpy 22 when the pipe 4 functions as a gas pipe, and the refrigerant enthalpy 23 on each indoor unit 2 side, 24, there is a difference in the heat loss.

  On the other hand, when the pipe 4 is a gas pipe, on the contrary, it is thick and has a large pipe diameter and a large surface area, so that it is easily affected by heat loss. However, in general, a heat insulating material is sufficient to prevent condensation. Insulation is done. Therefore, the heat loss is extremely small compared with the cooling capacity and can be ignored. Therefore, there is no problem in the arrangement of a normal outdoor unit or indoor unit.

However, when the refrigerant pipe is extremely long or when the ambient temperature of the refrigerant pipe is expected to be high, the heat loss is calculated by multiplying the heat loss of the refrigerant pipe and heat insulating material per unit length by the pipe length, It is preferable to correct the cooling capacity. Therefore, in such a case, heat loss from the heat insulating material per unit length of the refrigerant pipe: LO [kW / m]
When the refrigerant pipe length is L [m],
It is preferable to obtain by the following formula.
A = F * S / 3600 [sec / h] * {(GP-LP)-(HC) / (F * S / 3600 [sec / h])} + L * LO

More strictly speaking, when the pipe 3 is a liquid pipe and the pipe 4 is a gas pipe, the pipe 3 is on the heat radiation side and the gas pipe 4 is on the heat receiving side. If the side that increases A is + (plus side),
L × LO = L × Lo (liquid pipe heat radiation) −L × Lo (gas pipe heat reception)
If L is common,
From L × LO = L × {Lo (liquid pipe heat dissipation) −Lo (gas pipe heat receiving)},
LO = Lo (liquid pipe heat radiation) −Lo (gas pipe heat reception).

The following can be proposed as an apparatus for carrying out the refrigerant flow rate measuring method of the present invention.
That is, an ultrasonic flowmeter that measures the flow rate of the fluid in the pipe through which the refrigerant that has been liquefied in the refrigeration cycle flows, and a pipe that is installed upstream of the position where the transducer of the ultrasonic flowmeter is attached to the pipe A refrigerant flow rate measuring device comprising: a cooling device that cools the refrigerant in the pipe; and a heating device that is installed downstream of the position where the transducer is attached to the pipe and heats the refrigerant in the pipe. is there.

  If this refrigerant | coolant flow measuring device is used, it is possible to implement suitably the measuring method of the refrigerant | coolant flow volume of this invention. In addition, since the heating device and the cooling device can be externally attached to the refrigerant pipe, the entire refrigerant flow measuring device including the ultrasonic flowmeter can be unitized. Therefore, it can be attached to existing equipment and measured, and after measurement, it can be removed and taken away. Of course, it can be used for trial operation adjustment at the time of new construction, and is versatile.

  As the heating device, for example, an electric heater, a hot water jacket that circulates hot water can be used, and as the cooling device, a cooling jacket that circulates brine can be used. It is necessary to operate the device simultaneously. In such a case, as described above, the relationship between the amount of cooling heat and the amount of heating is such that when the amount of cooling heat and the amount of heating of the refrigerant are equal, the most accurate operation performance can be measured. From the viewpoint of carrying out at the same time and equalizing the amount of heat of both, it can be proposed to use the heat absorption side of the Peltier element as the cooling device and use the heat generation side of the Peltier element as the heating device. By using the heating device and the cooling device having such a configuration, heat absorption and heat generation (heat radiation) are generated simultaneously by the application of electric power, so that there is no need to newly provide a mechanism for interlocking the cooling unit and the heating unit. Further, by adjusting the amount of heat generated by the electrical resistance in the element with, for example, an element coolant, the heating amount can be adjusted to an appropriate amount, and the amount of cooling heat and the amount of heating can be easily controlled.

  According to the present invention, it is possible to accurately measure the flow rate of the refrigerant circulating under the vapor compression refrigeration cycle with an ultrasonic flowmeter without greatly affecting the operation state.

  Hereinafter, a preferred embodiment will be described. FIG. 3 shows an outline of an air conditioner having a vapor compression refrigeration cycle which attempts to measure the flow rate of the refrigerant using the refrigerant flow rate measuring device according to the present embodiment. In this example, as in FIG. 2, during cooling operation, the refrigerant condensed and liquefied by the condenser 5 of the outdoor unit 1 is sent to the indoor unit 2 through the pipe 3 and functions as an evaporator. The refrigerant evaporated by the machine 2 is returned to the compressor 6 through the pipe 4.

  The present embodiment has an ultrasonic flow meter 31 for measuring the refrigerant in the pipe 3 through which the refrigerant after liquefaction in such a refrigeration cycle flows. The ultrasonic flowmeter 31 includes transducers 32 and 33 as sensors for transmitting and receiving a pair of ultrasonic waves that are attached to two locations on the surface of the pipe 3 at different positions on the upstream side and the downstream side. The time when the ultrasonic waves are received when they are transmitted and received between the transducers 32 and 33 is measured, and the flow rate of the fluid flowing in the pipe 3 (liquefied refrigerant in this example) is obtained based on this time.

  And the cooling device 41 which cools the refrigerant | coolant in the piping 3 is provided in the surface of the piping 3 upstream of the area | region (measurement area) where these transducers 32 and 33 are attached, and the area | region (the transducers 32 and 33 are attached) A heating device 42 for heating the refrigerant in the pipe 3 is provided on the surface of the pipe 3 on the downstream side of the measurement section). The cooling device 41 and the heating device 42 are configured to be detachable from the piping using, for example, a sheet-like member wound around the piping. The cooling heat amount by the cooling device 41 is about 10% of the cooling capacity (about 1 to several kW), and the heating amount by the heating device 42 is set to be equal to or more than the cooling heat amount by the cooling device 41. This is because when the amount of heat of cooling is greater than the amount of heating, if the gas-liquid two-phase changes to the liquid phase, the pressure loss of the liquid pipe will be reduced, which will greatly change the ability to measure and the efficiency. However, when the heating amount is larger than the cooling heat amount, the gas-liquid two-phase state is not changed from the original state, so that the influence is considered to be small compared to the former.

  If the refrigerant flow rate measuring apparatus according to this embodiment is used, the refrigerant in the pipe 3 is cooled by the cooling device 41 so that the refrigerant in the gas-liquid two-phase state is brought into the liquid phase state (full liquid state). In addition, the refrigerant can be heated by the heating device 42 to return the refrigerant in the liquid phase state (full liquid state) to the gas-liquid two-phase state before cooling again. Therefore, in the region (measurement section) where the transducers 32 and 33 are attached, it is possible to measure the flow rate of the refrigerant with high accuracy by performing ultrasonic flow rate measurement on the liquid phase (full liquid state) refrigerant. In addition, after measuring the flow rate of the refrigerant in this way, the refrigerant can be heated by the heating device 42 to return the refrigerant in the liquid phase state (full liquid state) to the gas-liquid two-phase state before cooling again. Returning to the same gas-liquid two-phase state as before cooling, the operating state of the refrigeration cycle is not significantly changed. In addition, since these cooling device 41, heating device 42, and ultrasonic flow meter 31 transducers 32 and 33 are all applicable to existing piping, it is possible to actually measure the operating performance of the equipment in operation. They can be easily taken away after measurement.

  Next, examples of the heating device and the cooling device will be described. The cooling device shown in FIG. 3 is configured as a cooling jacket 51 that is detachable from the pipe 3 in which brine circulates. The brine that circulates in the cooling jacket 51 is sent from the brine cooling tank 52 to the cooling jacket 51 through the forward pipe 54 by the pump 53, and the brine that has been heated by cooling the refrigerant in the pipe 3 by the cooling jacket 51 is returned. It returns to the brine cooling tank 52 through the pipe 55. The flow rate adjustment of the brine is controlled by a flow rate adjustment valve 56 provided in the outgoing pipe 54. The outgoing pipe 54 is provided with a thermometer 57 and a flow meter 58, and the return pipe 55 is provided with a thermometer 59. By these, the amount of cooling heat is measured.

  On the other hand, the heating device is configured as a hot water jacket 61 that is detachable from the pipe 3 through which hot water circulates. Hot water circulating in the hot water jacket 61 is sent from the hot water heating tank 62 to the hot water jacket 61 through the outgoing pipe 64 by the pump 63, and the hot water cooled by heating the refrigerant in the pipe 3 by the hot water jacket 61 is returned to the return pipe. It returns to the warm water heating tank 62 through 65. The flow rate adjustment of the hot water is controlled by a flow rate adjustment valve 66 provided in the outgoing pipe 64. The outgoing pipe 64 is provided with a thermometer 67 and a flow meter 68, and the return pipe 65 is provided with a thermometer 69. By these, the heating amount is measured.

  By the way, in this invention, it is necessary to operate | move a heating apparatus and a cooling device simultaneously. Therefore, in the example shown in FIG. 4, for example, the cooling-side brine pump 53 and the heating-side hot water pump 63 need to synchronize on / off. In view of this point, in the example shown in FIG. 4, the pumps 53 and 63 are both controlled by the inverter control devices 50 and 60, and the inverter control devices 50 and 60 are controlled by the control device CR. The amount of cooling heat by the cooling jacket 51 and the amount of heating by the hot water jacket 61 are also controlled by the control device CR.

  In the example shown in FIG. 5, a cooling jacket 51 in which brine circulates is used on the cooling side, as in FIG. 4, but an electric heater 71 that generates heat when power is supplied is used on the heating side. That is, the electric heater 71 is configured to generate heat by the electric power supplied from the AC power source 72 through the cables 73 and 74 to superheat the refrigerant in the pipe 3. It can be freely attached to. The heating amount is measured by the wattmeter 75. The power supply amount of the AC power supply 72 and the supply start / stop are controlled by a control device 76 such as a thyristor. Even in the electric heater 71 as a heating device having such a configuration, it is necessary to synchronize the start and stop with the cooling jacket 51 as a cooling device, or to control the amount of cooling heat and the amount of heating. Thus, the inverter control device 50 and the control device 76 are controlled.

  In the example of FIGS. 4 and 5 described above, the cooling side and the heating side use different energy source system cooling devices and heating devices, but in the example shown in FIG. A Peltier element that can perform both cooling and heating simultaneously is used depending on the source system.

  The Peltier element 81 used in this example has P-type elements 82 and N-type elements 83 alternately arranged on the heat absorption side, that is, the cooling side, and the heat generation side, that is, the heating side, and connected in series by the metal plate 84. Furthermore, the P-type element 82 and the N-type element 83 on the cooling side and the heating side are connected by lead wires 85 and 86, respectively. On the heat absorption side, that is, the cooling side, a heat transfer material 87 is arranged on one side surface of the metal plate 84, and the heat transfer material 87 is detachably attached to the pipe 3 and has an outer periphery of the jacket 88 having good heat transfer properties. It has the structure attached to. On the other hand, the heat generation side, that is, the heating side is also provided with a heat transfer material 89 on one side surface of the metal plate 84, and the heat transfer material 89 is detachable from the pipe 3 and has a good heat transfer property. It has the structure attached to the outer periphery. The heat transfer material 89 can be cooled by, for example, tubes 91 and 92 for allowing the coolant to enter and exit.

  If the Peltier element 81 having such a configuration is used, a P-type element 82 and an N-type element 83 arranged on the cooling side are supplied by supplying a DC current from a DC power supply 93 via, for example, lead wires 85 and 86. Then, an endothermic effect occurs, and the P-type element 82 and the N-type element 83 arranged on the heating side generate an exothermic (heat radiating) action. Therefore, the cooling-side jacket 88 cools the refrigerant in the pipe 3, and the heating-side jacket 90 heats the refrigerant in the pipe 3.

  If the Peltier element 81 is used in this manner, cooling and heating can be performed simultaneously, and a control device that synchronizes these operations is unnecessary. For example, as shown in FIG. An open / close switch 94 may be provided in the supply circuit. Moreover, the cooling and heating by the Peltier element 81 is one energy source system, and the control of the cooling liquid supplied to the heat transfer material 89 on the heating side is sufficient for the control of the cooling heat amount and the heating amount.

  Next, according to the present invention, an example of performance measurement of a multi air conditioning system for buildings will be described. The configuration shown in FIG. 7 is the same as that shown in FIGS. 2 and 3 in the configuration of the refrigeration cycle, and the configuration of the cooling device and the configuration of the heating device are the same as those shown in FIG. The cooling jacket 51 used and the hot water jacket 61 using hot water are used, and the configuration of the peripheral devices is the same as the example shown in FIG. This is the same as the example shown in FIG.

  As shown in FIG. 7, the ultrasonic flowmeter 31 described above is used to measure the flow rate (volume flow rate) of the liquefied refrigerant flowing in the pipe 3. The enthalpy 21 of the liquefied refrigerant is based on the measurement results of the thermometer 11 and the pressure gauge 12 provided on the outdoor unit 1 side in the pipe 3, and the enthalpy 22 of the gasified refrigerant is on the outdoor unit 1 side in the pipe 4. The measurement results of the provided thermometer 13 and pressure gauge 14 are used. Further, power supplied from the AC power source 101 to the outdoor unit 1 side, that is, power consumption, is measured by a clamp-on type wattmeter 102. Further, as the temperature of the refrigerant in the liquid phase state (full liquid state) measured by the ultrasonic flow meter 31, the measurement value of the thermometer 103 attached to the measurement section in the pipe 3 is used. The temperature of the refrigerant in the liquid phase state (full liquid state) is compared with the saturated liquid temperature calculated from the measured pressure value of the refrigerant (liquid), and the full liquid state is confirmed. Used as a guide for setting the temperature input value. It may be input as a sound velocity value in the fluid calculated from the temperature. All the above measurement results are output to the data logger 104, and the obtained data is calculated and processed by the personal computer 105, for example.

  Next, the cooling / heating capacity exhibited by the outdoor unit 1 and the indoor unit 2 using such a configuration will be described. FIG. 8 is a Mollier diagram showing an outline during cooling. First, the refrigerant (gas) measurement and the refrigerant state at the refrigerant (liquid) measurement point are measured. The refrigerant enthalpy difference is obtained by subtracting the cooling calorie difference. If the volume flow rate measured by the ultrasonic flowmeter 31 is multiplied by the refrigerant flow rate (mass flow rate) obtained by multiplying the specific gravity of the refrigerant, the cooling capacity can be calculated. Further, by dividing this by power consumption, a coefficient of performance (COP) during cooling can be calculated.

  FIG. 9 is a Mollier diagram showing an outline during heating. The refrigerant state at the refrigerant (gas) measurement point and the refrigerant (liquid) measurement point is measured, and the heating amount of the refrigerant and the heat amount of cooling are calculated based on the difference. Subtract the difference to find the refrigerant enthalpy difference. If the volume flow rate measured by the ultrasonic flow meter 31 is multiplied by the refrigerant flow rate (mass flow rate) obtained by multiplying the specific gravity of the refrigerant, the heating capacity can be calculated. Moreover, the coefficient of performance (COP) at the time of heating can be calculated by dividing this by power consumption.

Explaining the above with a formula,
Cooling / heating capacity: A [kW]
Refrigerant flow rate: F [L / h]
Specific gravity of refrigerant: S [kg / L]
Gas refrigerant enthalpy: GP [kJ / kg]
Liquid refrigerant enthalpy: LP [kJ / kg]
Heating amount when the refrigerant is heated: H [kW]
Heat of cooling when the refrigerant is cooled: C [kW]
When
A = F * S / 3600 [sec / h] * {(GP-LP)-(HC) / (F * S / 3600 [sec / h])}
In addition, GP-LP becomes a freezing effect as an outdoor unit.

About coefficient of performance (COP)
Outdoor unit power consumption: W [kW]
COP = A / W.

  Next, description will be made on the result of the refrigerant flow measurement test using the ultrasonic flowmeter actually performed by the inventors. FIG. 10 shows an outline of the test method. The pipe 3 through which the liquefied refrigerant from the outdoor unit 1 flows is cooled by the cooling device 41, and the refrigerant in the pipe 3 is liquid-phased to be fully filled. State. A plate heat exchanger was used as the cooling device 41. The transducers 32 and 33 of the mass flow meter 111 and the ultrasonic flow meter 31 were installed on the downstream side of the cooling device 41. The refrigerant state was measured based on these measurement results by installing a pressure gauge 112 and a thin film platinum surface thermometer 113 on the downstream side of the cooling device 41. And the measured value of the refrigerant | coolant flow rate in a full liquid state and the state which is not full liquid was compared.

  FIG. 11 shows the test results. FIG. 11 shows an enthalpy a calculated from the measured values of the refrigerant pressure and the refrigerant temperature, and a saturated liquid enthalpy b calculated from the measured values of the refrigerant pressure. When the enthalpy a is smaller than the saturated liquid enthalpy b, the refrigerant is in a liquid state. The line c in the figure shows the refrigerant state with 1 when the refrigerant is full and 0 when the refrigerant is not full.

  First, cooling was performed by the cooling device 41 to make it full, and then the cooling device 41 was stopped and measurement was performed in a state where the cooling was not performed (not full). The results are shown in FIG. X indicates a measurement value obtained by the mass flow meter 111, and Y indicates a measurement value obtained by the ultrasonic flow meter. As can be seen from this figure, when the liquid is full, the measured values of the mass flow meter 111 and the ultrasonic flow meter 31 are in good agreement. However, when the second half of the measurement is not full, the indicated value of the ultrasonic flowmeter 31 is not obtained. In a state where the liquid is not full, the instruction of the mass flow meter 111 fluctuates, and although the degree of the mass flow meter varies depending on the manufacturer, it can be confirmed that the measurement accuracy is lowered. From the above, it was confirmed that the refrigerant flow rate was accurately measured by the ultrasonic flow meter 31 in a state in which the refrigerant in the pipe 3 was made into a liquid phase by cooling and filled.

  As described above, the contents of the present invention have been mainly explained by taking the refrigeration cycle in the outdoor unit and the indoor unit of the multi-air conditioning system for buildings as an example, but according to the present invention, by performing the refrigerant pipe surface temperature and pressure measurement together, In addition to multi-air conditioning systems for buildings, it is possible to measure refrigerant cycle capability and COP performance in packaged air conditioners (air cooling, water cooling) and condensing units.

  INDUSTRIAL APPLICABILITY The present invention is useful for measuring the capacity and coefficient of performance of refrigerant cycles of multi-air conditioning systems for buildings and packaged air conditioners, and is particularly useful for existing facilities.

It is a Mollier diagram showing the principle of the present invention. It is explanatory drawing which shows piping heat loss. It is explanatory drawing which shows the outline | summary and principle of the refrigerant | coolant flow rate measuring apparatus concerning embodiment. It is explanatory drawing which showed typically an example of the cooling device and heating device which can be used for embodiment. It is explanatory drawing which showed typically the other example of the cooling device and heating device which can be used for embodiment. It is explanatory drawing which showed typically the example which used the Peltier element for the cooling device and heating device which can be used for embodiment. It is explanatory drawing which showed typically the example of the apparatus structure which performs the performance measurement of a refrigerating cycle. It is the Mollier diagram which shows the outline | summary at the time of performing the performance measurement at the time of air_conditioning | cooling using the apparatus structure of FIG. It is the Mollier diagram which shows the outline | summary at the time of performing the performance measurement at the time of heating using the apparatus structure of FIG. It is explanatory drawing which shows the outline | summary of an apparatus structure at the time of measuring the refrigerant | coolant in piping with an ultrasonic flowmeter and a mass flowmeter. It is the graph which showed the comparison with the enthalpy calculated from the measured value of the refrigerant | coolant pressure and the refrigerant temperature using the apparatus structure of FIG. 10, and the saturated liquid enthalpy calculated from the measured value of the refrigerant pressure. It is a graph which shows the result of having measured the refrigerant | coolant in piping using an ultrasonic flowmeter and a mass flowmeter using the apparatus structure of FIG. It is a Mollier diagram by a prior art.

Explanation of symbols

1 Outdoor unit 2 Indoor unit 3 Piping (liquid pipe)
4 Piping (gas pipe)
DESCRIPTION OF SYMBOLS 5 Condenser 6 Compressor 11, 13 Thermometer 12, 14 Pressure gauge 31 Ultrasonic flow meter 32, 33 Transducer 41 Cooling device 42 Heating device 51 Cooling jacket 61 Hot water jacket

Claims (6)

A method for measuring the flow rate of refrigerant circulating under a vapor compression refrigeration cycle,
In the pipe through which the refrigerant after being liquefied in the refrigeration cycle flows, the refrigerant in the gas-liquid two-phase state is cooled to the liquid phase state,
Measure the flow rate of the refrigerant after being in the liquid phase state with an ultrasonic flow meter,
The refrigerant flow rate measuring method, wherein the refrigerant after the measurement is heated to a gas-liquid two-phase state before cooling. The refrigerant according to claim 1, wherein a relationship between a heating amount at the time of heating and a cooling heat amount at the time of cooling is a heating amount at the time of heating ≧ a cooling heat amount at the time of cooling. How to measure the flow rate. A method for determining the cooling / heating capacity of a refrigeration apparatus using the vapor compression refrigeration cycle based on the refrigerant flow rate obtained by using the refrigerant flow rate measurement method according to claim 1,
Cooling / heating capacity: A [kW]
Refrigerant flow rate: F [L / h]
Specific gravity of refrigerant: S [kg / L]
Gas refrigerant enthalpy: GP [kJ / kg]
Liquid refrigerant enthalpy: LP [kJ / kg]
Heating amount when the refrigerant is heated: H [kW]
Heat of cooling when the refrigerant is cooled: C [kW]
When
A method for obtaining a cooling / heating capacity of a refrigeration apparatus, characterized by obtaining the following equation.
A = F * S / 3600 [sec / h] * {(GP-LP)-(HC) / (F * S / 3600 [sec / h])} A method for determining the cooling / heating capacity of a refrigeration apparatus using the vapor compression refrigeration cycle based on the refrigerant flow rate obtained by using the refrigerant flow rate measurement method according to claim 1,
Cooling / heating capacity: A [kW]
Refrigerant flow rate: F [L / h]
Specific gravity of refrigerant: S [kg / L]
Gas refrigerant enthalpy: GP [kJ / kg]
Liquid refrigerant enthalpy: LP [kJ / kg]
Heating amount when the refrigerant is heated: H [kW]
Heat of cooling when the refrigerant is cooled: C [kW]
Heat loss from the heat insulating material per unit length of the pipe: LO [kW / m]
Pipe length of the pipe: L [m],
When
A method for obtaining a cooling / heating capacity of a refrigeration apparatus, characterized by obtaining the following equation.
A = F * S / 3600 [sec / h] * {(GP-LP)-(HC) / (F * S / 3600 [sec / h])} + L * LO An apparatus for measuring the flow rate of refrigerant circulating under a vapor compression refrigeration cycle,
An ultrasonic flowmeter that measures the flow rate of the fluid in the pipe through which the refrigerant after being liquefied in the refrigeration cycle flows;
A cooling device that is installed upstream of the position where the transducer of the ultrasonic flowmeter is attached to the pipe, and cools the refrigerant in the pipe;
A heating device installed on the downstream side of the position where the transducer is attached to the pipe, and heating the refrigerant in the pipe;
A refrigerant flow rate measuring device comprising: The refrigerant flow rate according to claim 5, wherein the cooling device is a cooling device using a heat absorption side of a Peltier element, and the heating device is a heating device using a heat generation side of the Peltier element. Measuring device.

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