JP2004239493A - Heat pump cycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump cycle for stabilizing desired heat absorbing capability for a long period. <P>SOLUTION: An evaporator 40 is arranged between an ejector 30 and a gas-liquid separator 50. Thus, refrigerant discharged from a compressor 10 is circulated in the evaporator 40, and so the amount of the refrigerant discharged from the compressor 10 is secured even when the pumping capability of the ejector 30 is greatly changed with an individual difference (manufacturing dispersion) or a secular change of the ejector 30. The great change in the amount of the refrigerant to be circulated in the evaporator 40 is suppressed to stabilize the desired heat absorbing capability for a long period. The flow rate of the refrigerant in the evaporator 40 is increased to increase heat transmissivity between the refrigerant and the evaporator 40. The heat exchanging capability, namely, the heat absorbing capability of the evaporator 40 is improved without increasing the size of the evaporator 40, resulting in the improved operating efficiency of the heat pump cycle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ejector cycle using an ejector among heat pump cycles utilizing heat generated on a high pressure side by transferring heat on a low temperature side to a high temperature side, and is effective when applied to a heating device or a hot water supply device. .
[0002]
[Prior art]
In general, an ejector cycle is a heat pump that decompresses and expands refrigerant in an ejector, sucks vapor-phase refrigerant evaporated in an evaporator, and converts expansion energy into pressure energy to increase the suction pressure of a compressor. Cycle (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-5-149652
[Problems to be solved by the invention]
However, in the above-described general ejector cycle, the refrigerant is circulated through the evaporator by the pumping action of the ejector (see JIS Z 8126 No. 2.1.2.3, etc.), and the solid-state difference of the ejector (production variation) and Since the pumping capacity of the ejector greatly changes due to aging, the amount of refrigerant circulating in the evaporator tends to fluctuate greatly, and it is difficult to stably obtain a desired heat absorbing capacity for a long period of time.
[0005]
In view of the above points, the present invention firstly provides a new heat pump cycle different from the conventional one, and secondly, aims to stably obtain a desired heat absorbing capacity for a long period of time.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is a heat pump cycle that uses heat generated on a high pressure side by moving heat on a low temperature side to a high temperature side. A compressor (10) for compression, a radiator (20) for radiating heat of the high-pressure refrigerant discharged from the compressor (10), and a nozzle (31) for decompressing and expanding the high-pressure refrigerant flowing out of the radiator (20). A momentum transport type ejector pump (30) for transporting the refrigerant by the action of entraining a high-speed refrigerant flow injected from the nozzle (31); and an evaporator (30) for evaporating the refrigerant discharged from the ejector pump (30). 40), the refrigerant flowing out of the evaporator (40) is separated into a gas-phase refrigerant and a liquid-phase refrigerant, and a gas-liquid separator (50) having an outlet for the gas-phase refrigerant connected to the suction side of the compressor (10). ) And a gas-liquid separator (5 ) And the evaporator (40) and a coolant passage means (60) which connects the coolant inlet side, characterized in that the refrigerant flows in the refrigerant passage means at the ejector pump (30) (60).
[0007]
Thereby, the high-pressure refrigerant discharged from the compressor (10) is cooled by the radiator (20), decompressed and expanded by the nozzle (31) of the ejector pump (30), and accelerated.
[0008]
Then, the refrigerant in the gas-liquid separator (50) is sucked by the pumping action caused by the entrainment action of the accelerated high-speed refrigerant, so that the refrigerant sucked through the refrigerant passage means (60) and the nozzle (31) ) Is mixed with the refrigerant blown out from the evaporator (40) and supplied to the evaporator (40).
[0009]
At this time, since the refrigerant flowing out of the ejector pump (30) is a wet refrigerant in a gas-liquid two-phase state, the liquid-phase refrigerant is vaporized in the evaporator (40), and the pressure in the gas-liquid separator (50) is reduced. That is, the suction pressure of the compressor (10) is stabilized at a higher pressure than the ejector cycle described in Patent Document 1.
[0010]
Therefore, the compression work of the compressor (10) can be reduced without lowering the temperature of the refrigerant discharged from the compressor (10), so that the operation efficiency of the heat pump cycle can be improved.
[0011]
Further, in the present invention, in addition to the refrigerant (mainstream) discharged from the compressor (10), the refrigerant (substream) sucked by the ejector pump (30) flows into the evaporator (40). In the invention described in Patent Document 1, only the refrigerant sucked by the ejector circulates in the evaporator.
[0012]
For this reason, in the present invention, since the flow rate of the refrigerant flowing in the evaporator (40), that is, the flow rate of the refrigerant in the evaporator (40) is larger than that of the invention described in Patent Document 1, the flow rate between the refrigerant and the evaporator (40) is increased. The heat transfer coefficient increases. Therefore, the heat exchange capacity, that is, the heat absorption capacity of the evaporator (40) can be improved without increasing the size of the evaporator (40), so that the operation efficiency of the heat pump cycle can be improved.
[0013]
In addition, since the refrigerant discharged from the compressor (10) circulates through the evaporator (40), the pump capacity of the ejector pump (30) is reduced due to a difference in solids (manufacturing variation) of the ejector pump (30) and aging. Even if there is a large change, the amount of refrigerant discharged from the compressor (10) can be reliably ensured.
[0014]
Therefore, the amount of the refrigerant circulating in the evaporator (40) can be prevented from greatly changing, and the desired heat absorbing ability can be stably obtained for a long period of time.
[0015]
The invention according to claim 2 is characterized in that the refrigerant passage means (60) is provided with a heating means (70) for exchanging heat with the atmosphere to heat the refrigerant.
[0016]
As a result, the gas-phase refrigerant whose volume flow rate, that is, the flow velocity increases, is sucked by the ejector pump (30), so that the refrigerant flow velocity in the evaporator (40) can be more reliably increased.
[0017]
As a result, the heat exchange capacity of the evaporator (40), that is, the heat absorption capacity can be surely improved without increasing the size of the evaporator (40), so that the operation efficiency of the heat pump cycle can be improved. .
[0018]
The invention according to claim 3 is characterized in that the refrigerant passage means (60) is connected to an outlet of the gas-liquid separator (50) for mainly discharging the liquid-phase refrigerant.
[0019]
The invention according to claim 4 is characterized in that the refrigerant passage means (60) is connected to an outlet of the gas-liquid separator (50) for mainly discharging the gas-phase refrigerant.
[0020]
Thereby, the flow velocity of the refrigerant in the evaporator (40) can be more reliably increased.
[0021]
According to a fifth aspect of the present invention, the ejector pump (30) is of a variable type that can change the throttle opening of the nozzle (31).
[0022]
Accordingly, if the throttle opening of the nozzle (31) is increased and the high-temperature refrigerant is supplied to the evaporator (40) as compared with the case where the refrigerant is evaporated by the evaporator (40), the evaporator (40) can be easily formed. ) Can be performed.
[0023]
According to a sixth aspect of the present invention, the discharge pressure of the compressor (10) is equal to or higher than the critical pressure of the refrigerant.
[0024]
According to a seventh aspect of the present invention, carbon dioxide is used as the refrigerant.
[0025]
Incidentally, reference numerals in parentheses of the above-mentioned units are examples showing the correspondence with specific units described in the embodiments described later.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
In this embodiment, a heat pump cycle according to the present invention is applied to a water heater, and FIG. 1 is a schematic diagram of a water heater (heat pump cycle).
[0027]
The compressor 10 sucks and compresses the refrigerant, and the water-refrigerant heat exchanger 20 cools the refrigerant by heating the hot water by exchanging heat between the refrigerant discharged from the compressor 10 and the hot water in a counterflow state. It is a radiator.
[0028]
The compressor 10 is driven by an electric motor (not shown). In the present embodiment, the rotation speed of the compressor 10, that is, the compressor 10 is controlled so that the discharge refrigerant temperature or discharge refrigerant pressure becomes a predetermined value. The flow rate of the refrigerant discharged from is controlled.
[0029]
Incidentally, in the present embodiment, carbon dioxide is used as the refrigerant, but it goes without saying that Freon (R404a or R410a) may be used as the refrigerant.
[0030]
When chlorofluorocarbon is used as the refrigerant, the enthalpy is reduced by condensing the refrigerant in the water-refrigerant heat exchanger 20, but when carbon dioxide is used as the refrigerant, the pressure of the high-pressure side refrigerant increases. And the enthalpy decreases because the refrigerant temperature decreases from the refrigerant inlet side to the refrigerant outlet side without condensing the refrigerant in the water-refrigerant heat exchanger 20.
[0031]
The ejector 30 is an ejector type pump that decompresses the high-pressure refrigerant flowing out of the water-refrigerant heat exchanger 20 and converts expansion energy into pressure energy to generate a pump action.
[0032]
Specifically, as shown in FIG. 2, a nozzle 31 for decompressing and expanding the high-pressure refrigerant flowing out of the water-refrigerant heat exchanger 20, while sucking the refrigerant by the entrainment of the high-speed refrigerant flow injected from the nozzle 31, From a mixing unit 32 that mixes the refrigerant flow injected from the nozzle 31 with the refrigerant flow, and a diffuser 33 that converts the velocity energy into pressure energy while increasing the pressure of the refrigerant while mixing the refrigerant injected from the nozzle 31 and the sucked refrigerant. It becomes.
[0033]
Incidentally, in the present embodiment, in order to accelerate the speed of the refrigerant ejected from the nozzle 31 to the speed of sound or more, a Laval nozzle having a throat portion having the smallest passage area in the middle of the passage (see Fluid Engineering (Tokyo University Press)). Although adopted, the present invention is not limited to this, and for example, a tapered nozzle may be used.
[0034]
In addition, in the mixing unit 32, mixing is performed so that the sum of the momentum of the refrigerant flow injected from the nozzle 31 and the momentum of the refrigerant flow sucked from the evaporator 40 to the ejector 30 is preserved. Also, the static pressure of the refrigerant increases.
[0035]
On the other hand, in the diffuser 33, the dynamic pressure of the refrigerant is converted into static pressure by gradually increasing the cross-sectional area of the passage, so in the ejector 30, the refrigerant pressure is increased by both the mixing unit 32 and the diffuser 33. . Therefore, the mixing section 32 and the diffuser 33 are collectively called a boosting section.
[0036]
In FIG. 1, the evaporator 40 is a low-pressure side heat exchanger that recovers heat from the outdoor air by exchanging heat between the refrigerant discharged from the ejector 30 and the outdoor air to evaporate the liquid-phase refrigerant, The gas-liquid separator 50 is a gas-liquid separation unit that stores the refrigerant by flowing the refrigerant flowing out of the evaporator 40 and separating the flowed refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant. The gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the suction side of the compressor 10.
[0037]
The refrigerant injection circuit 60 is a sub-refrigerant circuit that serves as a refrigerant passage unit that connects the gas-liquid separator 50 and the refrigerant inlet side of the evaporator 40, and a part of the refrigerant in the gas-liquid separator 50 It is supplied to the evaporator 40 via the refrigerant injection circuit 60 by a pump action.
[0038]
Next, the operation and effect of the present embodiment will be described.
[0039]
The high-pressure refrigerant discharged from the compressor 10 is cooled by the water-refrigerant heat exchanger 20, isentropically decompressed and expanded by the nozzle 31 of the ejector 30, and flows into the mixing section 32 at a speed higher than the speed of sound.
[0040]
Since the refrigerant in the gas-liquid separator 50 is sucked into the mixing unit 32 by the pumping action accompanying the entrainment of the high-speed refrigerant flowing into the mixing unit 32, the refrigerant drawn through the refrigerant injection circuit 60 While being mixed in the mixing unit 32 with the refrigerant blown out from the nozzle 31, the dynamic pressure thereof is converted to a static pressure by the diffuser 33 and supplied to the evaporator 40.
[0041]
At this time, since the refrigerant flowing out of the ejector 30 is a wet refrigerant in a gas-liquid two-phase state, the liquid-phase refrigerant absorbs heat from the outside air and evaporates in the evaporator 40, and the pressure in the gas-liquid separator 50, that is, compression. The suction pressure of the machine 10 is stabilized at a higher pressure than the ejector cycle described in Patent Document 1.
[0042]
Therefore, the compression work of the compressor 10 can be reduced without lowering the temperature of the refrigerant discharged from the compressor 10, that is, the supply water temperature, so that the operation efficiency of the heat pump cycle (water heater) can be improved. it can.
[0043]
Further, in the present embodiment, in addition to the refrigerant (main stream) discharged from the compressor 10, the refrigerant (sub-stream) sucked by the ejector 30 flows into the evaporator 40, as described in Patent Document 1. According to the invention, only the refrigerant sucked by the ejector circulates in the evaporator.
[0044]
For this reason, in the present embodiment, since the flow rate of the refrigerant flowing in the evaporator 40, that is, the flow velocity of the refrigerant in the evaporator 40, is greater than that of the invention described in Patent Document 1, the heat transfer coefficient between the refrigerant and the evaporator 40 is increased. I do. Therefore, the heat exchange capacity, that is, the heat absorption capacity of the evaporator 40 can be improved without increasing the size of the evaporator 40, so that the operation efficiency of the heat pump cycle (water heater) can be improved.
[0045]
In addition, since the refrigerant discharged from the compressor 10 circulates through the evaporator 40, even if the pump capacity of the ejector 30 greatly changes due to individual differences (manufacturing variation) of the ejector 30 or aging, the compressor 10 does not. The discharged refrigerant amount can be reliably ensured. Therefore, since the amount of the refrigerant circulating in the evaporator 40 can be prevented from greatly changing, the desired heat absorbing ability can be stably obtained for a long period of time.
[0046]
By the way, in the present embodiment, since the refrigerant injection circuit 60 is connected to the outlet provided mainly below the gas-liquid separator 50 for allowing the liquid-phase refrigerant to flow out, the liquid-phase refrigerant is supplied as a sub-flow. However, in order to further increase the flow rate of the refrigerant in the evaporator 40, it is desirable to connect the refrigerant injection circuit 60 to an outlet provided mainly above the gas-liquid separator 50 and mainly for discharging the gas-phase refrigerant. .
[0047]
Needless to say, the refrigerant in the gas-liquid two-phase state may be supplied to the refrigerant injection circuit 60.
[0048]
(2nd Embodiment)
In this embodiment, as shown in FIG. 3, a second evaporator 70 serving as a heating unit for heating a refrigerant by exchanging heat with an atmosphere is provided in the refrigerant injection circuit 60.
[0049]
As a result, the gas-phase refrigerant whose volume flow rate, that is, the flow velocity increases, is sucked into the ejector 30, so that the refrigerant flow velocity in the evaporator 40 can be more reliably increased. As a result, the heat exchange capacity of the evaporator 40, that is, the heat absorption capacity can be surely improved without increasing the size of the evaporator 40, so that the operation efficiency of the heat pump cycle (water heater) can be improved. .
[0050]
In the present embodiment, the second evaporator 70, that is, a dedicated heat exchanger is provided in the refrigerant injection circuit 60, but fins are provided in the refrigerant injection circuit 60 or the refrigerant injection circuit 60 is meandered. The refrigerant injection circuit 60 itself may be made to function as a heating unit for exchanging heat with the atmosphere to heat the refrigerant.
[0051]
(Third embodiment)
In the present embodiment, as the ejector 30, a variable ejector capable of changing the throttle opening of the nozzle 31 is employed.
[0052]
The degree of opening of the throttle of the nozzle 31 is controlled so that the degree of superheat of the refrigerant at the outlet of the evaporator 40 becomes a predetermined value, or based on the temperature of the refrigerant at the outlet of the water-refrigerant heat exchanger 20, that is, the temperature of the high-pressure refrigerant. For example, control may be performed such that the target high-pressure side pressure is determined.
[0053]
Incidentally, the target high-pressure side pressure is a high-pressure side pressure at which the coefficient of performance of the heat pump cycle becomes a predetermined value or more using the temperature of the high-pressure refrigerant as a parameter.
[0054]
Further, during the defrosting operation for removing frost generated on the surface of the evaporator 40, the supply of hot water to the water-refrigerant heat exchanger 20 is stopped to stop heat radiation in the water-refrigerant heat exchanger 20, and The evaporator 40 is heated from the inside by increasing the throttle opening of the nozzle 31 and supplying a high-temperature refrigerant to the evaporator 40 as compared with the case where the refrigerant is evaporated by the evaporator 40.
[0055]
Accordingly, the defrosting operation can be easily performed without providing a bypass refrigerant circuit, a solenoid valve, or the like dedicated to the defrosting operation, so that the defrosting operation can be performed while suppressing an increase in the manufacturing cost of the heat pump cycle. A heat pump cycle that can be obtained can be obtained.
[0056]
(Other embodiments)
In the above embodiment, the present invention is applied to the hot water supply device, but the present invention is not limited to this, and can be applied to, for example, a heating device.
[0057]
Further, an internal heat exchanger for exchanging heat between the refrigerant sucked by the compressor 10 and the refrigerant depressurized by the ejector 30, or an external heat exchanger for exchanging heat between the refrigerant sucked by the compressor 10 and the atmosphere. May be provided.
[0058]
In the above-described embodiment, the compressor 10 is driven by the electric motor. However, the present invention is not limited to this. For example, the compressor 10 may be driven by an internal combustion engine.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a water heater according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram of an ejector according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of a water heater according to a second embodiment of the present invention.
[Explanation of symbols]
10 ... Compressor, 20 ... Water refrigerant heat exchanger, 30 ... Ejector,
40: evaporator, 50: gas-liquid separator, 60: refrigerant injection circuit (sub circuit).

Claims (7)

A heat pump cycle that transfers the heat on the low temperature side to the high temperature side and uses the heat generated on the high pressure side,
A compressor (10) for sucking and compressing the refrigerant;
A radiator (20) for radiating heat of the high-pressure refrigerant discharged from the compressor (10);
A momentum transport type ejector pump having a nozzle (31) for decompressing and expanding the high-pressure refrigerant flowing out of the radiator (20), and transporting the refrigerant by an entrainment action of a high-speed refrigerant flow injected from the nozzle (31). (30)
An evaporator (40) for evaporating a refrigerant discharged from the ejector pump (30),
The refrigerant flowing out of the evaporator (40) is separated into a gas-phase refrigerant and a liquid-phase refrigerant, and a gas-liquid separator (50) having a gas-phase refrigerant outlet connected to the suction side of the compressor (10). ,
A refrigerant passage means (60) for connecting the gas-liquid separator (50) to a refrigerant inlet side of the evaporator (40);
A heat pump cycle, wherein a refrigerant flows through the refrigerant passage means (60) by the ejector pump (30). The heat pump cycle according to claim 1, wherein the refrigerant passage means (60) is provided with a heating means (70) for exchanging heat with an atmosphere to heat the refrigerant. The heat pump cycle according to claim 1, wherein the refrigerant passage means (60) is connected to an outlet of the gas-liquid separator (50) through which liquid refrigerant mainly flows out. The heat pump cycle according to claim 1, wherein the refrigerant passage means (60) is connected to an outlet of the gas-liquid separator (50) through which a gas-phase refrigerant mainly flows out. The heat pump cycle according to any one of claims 1 to 4, wherein the ejector pump (30) is a variable type capable of changing a throttle opening of the nozzle (31). The heat pump cycle according to any one of claims 1 to 5, wherein a discharge pressure of the compressor (10) is equal to or higher than a critical pressure of the refrigerant. The heat pump cycle according to any one of claims 1 to 6, wherein carbon dioxide is used as the refrigerant.

Images