JPH0474628B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a heat pump device such as an air conditioner using a non-azeotropic mixed refrigerant and a variable rotation speed compressor, which has recently attracted particular attention. Conventional technology The refrigeration cycle of a heat pump device using a non-azeotropic mixed refrigerant and a variable speed compressor, which is conventionally used in air conditioners, water heaters, etc., is shown in Fig. 4, which is well known in the past. It was something like that. Fourth
In the figure, 1 is a variable rotation speed compressor, 2 is a condenser, 3 is a throttle device, and 4 is an evaporator, which are connected in order through piping. Further, in order to drive the compressor 1, an AC power source 5 and a frequency converter 6 are connected as an electric circuit. Furthermore, when operating this type of refrigeration cycle, the relationship between the frequency and voltage output from the frequency converter 6 is such that at relatively low frequencies, the frequency and voltage are proportional, as shown in Figure 3. Also, at relatively high frequencies, the relationship was such that the voltage was constant. In addition, if the boiling point of the non-comixed refrigerant is low,
Both high and low pressure and refrigerant circulation amount increase, resulting in an increase in motor load torque. Conversely, when the boiling point is high, both high and low pressure and refrigerant circulation amount decrease, reducing motor load torque. When flowing a low-temperature non-azeotropic refrigerant mixture, increase the input voltage slightly,
When operating at full frequency and flowing a non-azeotropic refrigerant mixture with a high boiling point, the input voltage is slightly lowered, and the motor is operated at full frequency to ensure optimum motor efficiency for that refrigerant. By doing,
EER (refrigeration output/
It became possible to exceed the value of electrical input (electrical input) compared to when using a single refrigerant. Problems to be Solved by the Invention On the other hand, in recent years, amidst the movement to further reduce the annual power consumption of heat pump equipment, there has been a trend towards variable speed compressors and non-azeotropic refrigerant mixtures with a certain fixed composition. Although operating a heat pump device is more effective than when using a single refrigerant, it is not possible to operate the heat pump device in such a way that it can always handle the load of the heat pump device and fully demonstrate its effectiveness in terms of annual power consumption. It's getting difficult. In other words, when operating at all frequencies using a non-azeotropic mixed refrigerant with a relatively low boiling point, the specific suction volume of the compressor decreases and the refrigerant circulation amount increases, so high capacity can be achieved, and during high frequency operation, In other words, the EER could be maintained at a very high level under heavy loads, but during low-frequency operation, that is, under low loads, even if the input voltage to the compressor was adjusted as in the past, the refrigerant's Due to the large capacity, there were problems such as difficulty in balancing the load, so it did not have much effect on EER. In addition, when operating at full frequency using a non-azeotropic mixed refrigerant with a relatively high boiling point, conversely, the suction specific volume increases and the refrigerant circulation amount decreases, making it possible to achieve low capacity and operate at low frequencies. However, during high frequency operation, that is, when the load is large, even if the input voltage to the compressor is adjusted as in the past, the EER of the refrigerant can be maintained high. Due to the small capacity, there are problems such as difficulty in balancing the load.
There was no significant effect on EER. In other words, even if a non-azeotropic refrigerant mixture with a certain boiling point is operated in a variable speed compressor and the input voltage to the variable speed compressor is adjusted as in the past, the EER will not be optimal for that refrigerant. The load range (frequency range) in which this occurs is limited, and in the case of heat pump equipment where the load changes greatly over the year, even if the load changes greatly, it is unavoidable to use non-azeotropic heat pumps with the same boiling point. Since the compressor was operated using a mixed refrigerant and adjusting the compressor input voltage to optimize EER, the effect could not be said to be very large in terms of annual power consumption. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a heat pump device that can always provide a capacity corresponding to the load regardless of any changes in the load, and can further reduce annual power consumption. Means for Solving the Problems In order to achieve the above object, the present invention uses a non-azeotropic mixed refrigerant and connects a variable speed compressor, a condenser, a first throttling device, and an evaporator with piping. a circuit, comprising means for varying the refrigerant composition in the main circuit, and a ratio between the operating frequency (F) of the variable rotation speed compressor and the motor input voltage (V) of the variable rotation speed compressor ( V/F) is set higher when the composition in the main circuit is rich in low boiling point components, and set lower when the composition is rich in high boiling point components. Effect According to the above configuration, when the load on the heat pump device increases, the refrigerant composition variable means consisting of the sub-circuit specifically, the main circuit is enriched with low boiling point components due to the refrigerant rectification action, and as a result, , high and low pressure, and the amount of refrigerant circulation increase, so the motor load torque increases. Therefore, by slightly increasing the input voltage to the motor at the same frequency, it is possible to operate the motor at its optimum efficiency. However, it is possible to drive optimally.
In addition, when the load decreases, the motor load torque decreases as the composition is rich in high boiling point components, so it is possible to maintain optimal operation by slightly lowering the input voltage. . Embodiment An embodiment of a heat pump device according to the present invention will be described based on FIGS. 1 and 2. Here, 7 is a variable speed compressor (hereinafter referred to as a compressor), 8 is a condenser, 9 is a first throttle device, 10 is a second throttle device, and 11 is an evaporator, which is the main circuit of the refrigeration cycle. It is composed of 7, 8, 9, and 11. 12 is a refrigerant rectification column, 13 is a top reservoir, 14
15a and 15b are electromagnetic valves, and 10, 12, 13, 14, 15 are subcircuits of composition variable means.
It is composed of a and 15b. Further, a heating source 16 is arranged in the tower bottom reservoir 14 and a cooling source 17 is arranged in the tower top reservoir 13. Also, in order to drive the compressor 7, the AC power supply 18 is connected to a frequency converter 19.
is supplied through. In the heat pump device configured as described above, the operation was as follows. The refrigerant gas discharged from the compressor 7 flows in the direction of the solid arrow, is liquefied in the condenser 8, and is split into two directions at the branch point A, one of which flows into the expansion device 9 and expands to a low pressure. The other flows into the bottom reservoir 14 where the incoming refrigerant is heated by the heating source 16 to boiling. To make the main circuit rich in high boiling point components, close the solenoid valve 15a,
By opening b, the low boiling point refrigerant gas generated in the tower bottom reservoir 14 rises due to the so-called rectification effect, and while exchanging heat and material with the descending liquid, a gas rich in extremely low boiling point components is generated. It rises, is cooled and liquefied by the cooling source 17, and accumulates in the tower top reservoir 13. On the other hand, the gas rich in low boiling point components is vaporized and the liquid rich in high boiling point components left behind flows into the second throttle device 10 through the electromagnetic valve 15b, and at the confluence point B,
It joins with the refrigerant that has exited the first throttle device 9 mentioned earlier. In this way, the main circuit has a refrigerant composition rich in high boiling point components. Conversely, in order to make the main circuit rich in low boiling point components, by opening the solenoid valve 15a and closing the solenoid valve 15b, a refrigerant rich in high boiling point components is added to the bottom reservoir 14. This is achieved by the stored refrigerant rich in low boiling point components flowing into the main circuit. In this way, the solenoid valve 15a is opened and the solenoid valve 15a is opened.
By closing b, the high boiling point refrigerant is stored in the tower bottom reservoir 14, and as a result, the main circuit becomes a refrigerant rich in low boiling point composition, and the solenoid valve 15a is closed and the solenoid valve 15b is opened. As a result, the main circuit becomes a refrigerant rich in high boiling point components. Therefore,
Even if the composition itself is not detected, the solenoid valve 15a,
The refrigerant composition in the main circuit is changed according to the opening/closing operation of the solenoid valve 15b, and the ratio (V/F) between the operating frequency (F) of the compressor 7 and the motor input voltage (V) is changed. When the load on the heat pump equipment is large, it is recommended to use a component rich in low boiling point components that can increase the capacity and operate in a high frequency range, in order to cope with the load and improve EER. , as mentioned above,
Both high and low pressures rise and the amount of refrigerant circulation increases,
The motor load torque increases. Therefore, by increasing the input voltage to the motor a little higher, it becomes possible to operate the motor at a point where the motor efficiency is optimized.
On the other hand, when the load on the heat pump equipment is small, it is better to operate the heat pump in a low-frequency region with a high-boiling-point component with low capacity, and in terms of load response and EER. , as mentioned above,
As both high and low pressures decrease and the amount of refrigerant circulating decreases,
Motor load torque decreases. Therefore, by lowering the input voltage to the motor slightly, it becomes possible to operate the motor at a point where the motor efficiency is optimized. Specifically, as shown in Figure 2, if you take the operating frequency horizontally and the motor input voltage vertically, the best method is to operate with the main circuit composition and voltage versus frequency as shown by the solid line in the diagram. . In other words, the composition of the refrigerant flowing in the main circuit is varied according to the load of the heat pump device, in other words, the operating frequency (F), and the ratio between the operating frequency (F) of the compressor 7 and the motor input voltage (V) is changed. By setting (V/F) higher when the composition in the main circuit is rich in low-boiling point components and lower when it is rich in high-boiling point components, the optimal refrigerant composition corresponding to the load at that time can be set. and motor input voltage, and the EER is always optimal. In addition, in order to experimentally verify the present invention, we used R22, a low boiling point component, and R12, a high boiling point component, as a non-azeotropic mixed refrigerant, and used one air-cooled refrigeration cycle (air conditioner) to vary the composition. Operate without adding a bypass circuit. In this case, the refrigerant is
Mixed refrigerant A, which is a mixture of 20% R22 and 80% refrigerant R12, and 60% refrigerant R22 and refrigerant R12
and mixed refrigerant B, which was a mixture of 40% of each, were separately sealed. That is, the table shows the results of checking the composition change (from A to B) of the main circuit that occurs when the main circuit is operated with the addition of a bypass circuit that changes the composition by sealing different mixed refrigerants. As is clear from the table, at low load (30Hz operation), when operating with mixed refrigerant A, the voltage is 51V and the EER reaches the maximum value of 3.95 at that frequency and composition, and when mixed refrigerant B
When operated at a voltage of 58V, the EER reached the maximum value of 3.84 at that frequency and composition. In other words, the value of the ratio (V/F) between the operating frequency (F) of the compressor 7 and the motor input voltage (V) is higher when mixed refrigerant B is rich in low boiling point composition than when mixed refrigerant A is used. This shows that by setting EER to a high value, EER will also reach its maximum value at that time. Similarly, at high load (75Hz operation)
For this case, when a bypass circuit that changes the composition is added and the system is operated, the EER is maximized by setting the V/F value higher than when the fuel is rich in high-boiling point compositions. here,
Since the comparison was made using an experiment with a constant frequency, there will be some differences in performance, but similar results were obtained even when the performance was combined, and this experiment verified the effectiveness of the present invention. did it.

[Table] Effects of the Invention As described above, the present invention uses a non-azeotropic mixed refrigerant to vary the refrigerant composition flowing in the main circuit according to the load, and adjusts the operating frequency of the variable rotation speed compressor at that time. By varying the input voltage accordingly, it is effective to always keep the EER at the optimum level. Furthermore, since it is possible to maintain high motor efficiency, effects such as reduction in heat generation and vibration of the motor, which contribute to improvement in reliability, are also significant.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of a heat pump device according to an embodiment of the present invention, and Fig. 2 is a diagram showing the input voltage to the variable rotation speed compressor of the heat pump device according to an embodiment of the present invention. A characteristic diagram showing the flowing refrigerant composition; Figure 3 is a characteristic diagram showing the input voltage to a conventional variable speed compressor with respect to frequency and refrigerant composition in the heat pump device; FIG. 2 is a principle diagram of a heat pump device using a non-azeotropic mixed refrigerant and a variable rotation speed compressor. 7... variable speed compressor, 8... condenser, 9
...First squeezing device, 10...Second squeezing device, 11
...Evaporator, 12...Refrigerant rectification column, 13...Tower top reservoir, 14...Tower bottom reservoir, 15...Solenoid valve,
16... Heating source, 17... Cooler, 18... AC power supply, 19... Frequency converter.

Claims (1)

[Claims] 1. Using a non-azeotropic mixed refrigerant, a variable rotation speed compressor, a condenser, a first throttling device, and an evaporator are connected via piping to form a main circuit, and the refrigerant composition in the main circuit is The ratio (V/F) between the operating frequency (F) of the variable rotation speed compressor and the motor input voltage (V) of the variable rotation speed compressor is controlled by the composition in the main circuit. The heat pump device is set at a higher temperature when it is rich in low boiling point components, and at a lower temperature when it is rich in high boiling point components. 2. The means for varying the refrigerant composition consists of a circuit that connects the refrigerant rectification column, the top reservoir, the second throttling device, and the solenoid valve with piping and bypasses the condenser outlet and evaporator inlet of the main circuit. Claim 1
Heat pump device as described in Section 1.