JP2007198693A - Cascade type heat pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat pump system, capable of creating a heat source having a large temperature difference between an inlet and an outlet to a cooling system while further reducing power consumption, and also easily creating a heat source of a desired temperature in a wide temperature range. <P>SOLUTION: In this cascade type heat pump system comprising a plurality of independent refrigeration cycles R1 and R2 each including a compressor 9, 10, an expander 11, 12 and an evaporators 7, 8 in which each refrigeration cycle shares freezing performance, refrigerant suction pressure and refrigerant discharge pressure in each compressor 3, 4 are set stepwise, and a passage for secondary-side heat medium 1, 2 is serially connected to each evaporator 7, 8 or condenser 9, 10 to successively perform heat exchange with the secondary heat medium in the evaporator or condenser, and the temperature of the secondary heat medium is changed stepwise, whereby cold heat or hot heat of a target temperature is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the heat pump system in which a plurality of independent refrigeration cycles are arranged in parallel and the refrigeration capacity is shared by each refrigeration cycle, thereby reducing power and improving the coefficient of performance, The present invention relates to a cascade type heat pump system in which cooling or heating at a target temperature is obtained by cooling or heating in stages by an evaporator group or a condenser group of a cycle.

In a refrigeration facility such as a beer factory, various cooling loads exist, and cooling temperatures are classified into several types. In addition, each cooling load changes its size and its ratio in the total load depending on the time zone.
Conventionally, such a cooling system that covers various temperatures and various cooling loads is disclosed in, for example, Patent Document 1 (Japanese Patent No. 2545162).

  This cooling system is a cooling system by a plurality of independent refrigeration cycles having a compressor, a condenser, an expansion valve and a condenser dedicated to each refrigeration cycle, and a plurality of cooling systems provided for each evaporation temperature on the compressor suction side. By selecting the opening / closing or throttling degree of the valve provided in the line from the line for each evaporation temperature, the refrigerant is sucked in from the line for each evaporation temperature that best suits each compressor at the maximum evaporation temperature of each compressor, Thus, the power consumption of each refrigeration cycle is reduced, and the power consumption of the refrigerator is reduced by distributing the optimum load among the refrigeration cycles.

Japanese Patent No. 2545162

However, although the cooling system disclosed in Patent Document 1 can reduce the power consumption of the refrigerator, each refrigeration cycle independently selects the optimal evaporation temperature for the corresponding cooling load, so that the entire system is It is not intended to improve thermal efficiency, and it is difficult to create a cold heat source having a large difference between the inlet temperature and the outlet temperature to the cooling system.
In addition, a plurality of evaporation temperature lines for each evaporation temperature are provided on the compressor suction side, and a plurality of suction lines are provided for each compressor between the plurality of evaporation temperature lines and the plurality of compressors. It is necessary to provide an on-off valve in each of the suction lines, which causes a problem that the equipment becomes large and the cost is high.

In view of the problems of the prior art, the present invention can further reduce the power consumption, and can create a heat source having a large difference between the inlet temperature and the outlet temperature of the heat pump system, and is desired in a wide temperature range. The object is to realize a heat pump system that can easily create a heat source of temperature.
Another object of the present invention is to simplify the arrangement and construction of the equipment constituting the refrigeration cycle by modularizing it and reducing the cost.

In order to achieve such an object, the first configuration of the cascade heat pump system of the present invention includes:
In a cascade heat pump system in which a plurality of refrigeration cycles each having a compressor, a condenser, an expander and an evaporator are arranged in parallel,
The flow path of the secondary side heat medium is connected in series from one side to the final stage to the evaporator group constituting the plurality of refrigeration cycles,
Set the refrigerant suction pressure of each compressor in order from one side to the last stage,
The secondary side heat medium is configured to flow in order from the evaporator having a high evaporation pressure toward the evaporator having a low evaporation pressure in the secondary side heat medium flow path.

  In the heat pump system of the present invention, the refrigerant suction pressures of the compressors of the plurality of refrigeration cycles are set in a stepped manner from one side toward the final stage, and the refrigeration capacity is assigned to the plurality of refrigeration cycles. As a result, the compression ratio of each refrigeration cycle can be reduced as compared with the case where it is constituted by one refrigeration cycle, so that the overall power consumption of each refrigeration cycle can be reduced.

In addition, the flow path of the secondary heat medium is connected to each evaporator of a plurality of refrigeration cycles in series in the order of the evaporator set to a high evaporation pressure (ie, compressor suction pressure), and the secondary heat medium is evaporated. It is made to flow in order from an evaporator having a high pressure toward an evaporator having a low evaporation pressure, and in this group of evaporators, heat exchange is sequentially performed with the secondary side heat medium so that the temperature of the secondary side heat medium is lowered stepwise. To do.
For this reason, compared to the power consumption for taking out the secondary heat medium at the final temperature in a single refrigeration cycle, for example, when cooling by sharing about 1/2 by two units, the power consumption of the first unit with a high evaporation pressure is It is possible to operate with less power consumption than 1/2 of the total power consumption.
Moreover, it becomes possible to produce the secondary side heat medium (cold heat) of arbitrary temperature by taking out when the secondary side heat medium becomes the temperature which wants to utilize.

The second configuration of the cascade heat pump system of the present invention is as follows.
In a cascade heat pump system in which a plurality of refrigeration cycles each having a compressor, a condenser, an expander and an evaporator are arranged in parallel,
The flow path of the secondary side heat medium is connected in series from one side to the final stage to the condenser group constituting the plurality of refrigeration cycles,
Set the refrigerant discharge pressure of each compressor in order from the one side to the final stage,
The secondary-side heat medium is configured to flow in order from the condenser having a low condensation pressure toward the condenser having a high condensation pressure in the secondary-side heat medium flow path.

In the second configuration of the present invention, the flow path of the secondary heat medium is connected in series from one side to the final stage to the condenser group constituting the plurality of refrigeration cycles, and the secondary heat medium is condensed to the condensing pressure. From the low-condenser condenser to the high-condenser pressure condenser, and the condenser group sequentially heat-exchanges with the secondary heat medium so that the temperature of the secondary heat medium rises stepwise. .
For this reason, compared to the power consumption for taking out the secondary heat medium at the final temperature in a single refrigeration cycle, for example, if the heat is radiated (heated) by sharing about 1/2 by two units, the consumption of the first unit with a low condensing pressure The power can be operated with less power consumption than 1/2 of the total power consumption.
Moreover, it becomes possible to produce the secondary side heat medium (warm heat) of arbitrary temperature by taking out when the secondary side heat medium becomes temperature to use.

The third configuration of the present invention is as follows.
The flow path of the secondary side heat medium is connected in series from the one side to the final stage to the evaporator group and the condenser group constituting the plurality of refrigeration cycles,
Set the refrigerant suction pressure of each compressor in order from one side to the last stage,
The secondary side heat medium flows in the secondary side heat medium flow path connected to the evaporator in order from an evaporator having a high evaporation pressure to an evaporator having a low evaporation pressure, and the secondary side heat medium connected to the condenser. The secondary heat medium is configured to flow in the medium flow path in order from a condenser having a low condensation pressure to a condenser having a high condensation pressure.

In the third configuration, when the secondary heat medium flow path is connected to both the evaporator and the condenser, the evaporator has the higher inlet pressure of the compressor as the inlet, and the compressor discharges the compressor. Connect the lower pressure one after another as an inlet.
As a result, it is possible to create a secondary heat medium having a large difference between the inlet temperature and the outlet temperature to the cooling system between the inlet and the outlet of the heat pump system of the present invention. A secondary heat medium whose temperature rises or falls stepwise in a flow path connected between the evaporator or the condenser is taken out from the flow path when the target temperature is reached, thereby providing a wide temperature range. The secondary side heat medium (cold heat and warm heat) having a desired temperature can be produced and supplied to various heat loads.

Further, in the present invention, each refrigeration cycle has a low compression ratio, and the refrigerant charging amount can be reduced in each refrigeration cycle. Therefore, the compressor power is reduced as compared with the case where the compressor refrigeration cycle is performed conventionally. Therefore, the coefficient of performance COP can be improved over the conventional method.
In addition, since the refrigerant charge is reduced and the compression ratio is reduced in each refrigeration cycle, it is safer to use HC (hydrocarbon) refrigerants such as propane, propylene, isobutane, or dimethylethyl ether. Can be used highly. Further, CO ₂ , ammonia and the like can be used as other natural refrigerants, but COP can be further improved by using ammonia with good thermophysical properties.

  According to the present invention, a conventional non-azeotropic refrigerant mixture is used, and a high thermal efficiency similar to that of the Lorentz cycle, which can achieve high efficiency by matching the liquefaction or vaporization speed gradient of the mixed refrigerant with the temperature change rate, is achieved in a single natural manner. This can be achieved with a system refrigerant. And since a single refrigerant | coolant is used, there is no fault that a heat exchanger becomes large like the case where a non-azeotropic mixed refrigerant | coolant is used.

  In the present invention, a screw type, a reciprocating type, a scroll type, or the like can be used for the compressor. Further, in the present invention, it is possible to obtain the best thermal efficiency by exchanging heat by connecting the flow path of the secondary heat medium to both the evaporator group and the condenser group of the multiple refrigeration cycles. Alternatively, heat exchange may be performed in either of the condenser groups.

FIG. 1A schematically shows one form according to the first configuration of the present invention. In FIG. 1A, three refrigeration cycles R1 to R3 are provided in parallel, and each of the refrigeration cycles includes an independent compressor C, an expansion valve F, and an evaporator E. The condenser is a refrigeration cycle. The integrated condenser D is common to R1 to R3.
The suction pressure (evaporation pressure) of each compressor is set in a stepwise manner such that C1 is 0.56 MPa, C2 is 0.46 MPa, and C3 is 0.36 MPa. The flow path of the secondary heat medium B evaporates. The secondary-side heat medium B is connected in series from the evaporators E1 to E3 to the lower one from the evaporator E1 having the higher evaporation pressure.

The condensing pressure of the condenser D, the condenser temperature, and the inlet and outlet temperatures at each of the evaporators E1 to E3 are as shown in the figure, and the secondary side heat medium B having various temperatures is supplied at the outlet of each of the evaporators E1 to E3. In addition to being able to take out, it is possible to take out cold heat having a large temperature difference between the inlet of the evaporator E1 and the outlet of the evaporator E3. On the other hand, the secondary heat medium A at 37 ° C. can be taken out at the outlet of the condenser D.
Further, by integrating the condenser D, the compression differential pressures of the compressors C1, C2, and C3 are reduced, thereby reducing the power consumption of the compressor. In addition, by unitizing the compressor and evaporator of each refrigeration cycle, the time and cost required for designing, manufacturing, and construction thereof can be reduced.

  FIG. 1 (b) shows a conventional one-stage refrigeration cycle. The pressure difference can be reduced by the present invention (compressor C1) compared to the high-low pressure difference (ΔP = 1.1 MPa) of the conventional refrigeration cycle. ΔP = 0.69 MPa, ΔP = 0.79 MPa for the compressor C 2, ΔP = 0.89 MPa for the compressor C 3), and the compressor power can be reduced. As a result, the coefficient of performance COP can be improved as compared with the conventional method.

  FIG. 2 (a) schematically shows an embodiment according to the second configuration of the present invention, and FIG. 2 (b) shows a conventional method in which a one-stage refrigeration cycle d is configured. . In the form of FIG. 2A, in the three-stage refrigeration cycles R1 to R3 arranged in parallel, each of the condensers is composed of independent condensers D1 to D3, and the condensation pressure (compressor discharge pressure) of each condenser is configured. ), The condenser D1 is set to 1.18 MPa, D2 is 1.59 MPa, and D3 is set to be different from each other in a stepped manner, while the evaporator E is an integrated type common to the refrigeration cycles R1 to R3. Is.

  In such a form, the secondary side heat medium A having various temperatures can be taken out at the outlets of the condensers D1 to D3, and a large temperature difference exists between the inlet of the condenser D3 and the outlet of the condenser D1. Heat can be taken out. Further, by integrating the evaporator E, the high / low pressure difference (ΔP = 0.82 MPa) of the refrigeration cycle R3 and the high / low pressure difference (ΔP = 1.23 MPa) of the refrigeration cycle R3 can be reduced, and FIG. Compared with the high-low pressure difference (ΔP = 1.47 MPa) of the conventional one-stage refrigeration cycle R shown in (1), the compression ratio can be reduced, whereby the COP can be improved over the conventional method.

  As shown in FIG. 3, in the refrigeration cycle, when the temperature of the refrigerant decreases and the evaporation pressure decreases, the refrigerant becomes diluted in the evaporation step, and the coefficient of performance COP decreases. For example, the COP is about 5 to 6 when the refrigerant temperature is 0 ° C., but when it reaches −100 ° C., it drops to 1 or less. In the present invention, the refrigerant amount of the refrigeration cycle having a low evaporating pressure on the low temperature side can be reduced by configuring a multi-stage refrigeration cycle and setting the evaporating pressure stepwise in each refrigeration cycle. Can be suppressed.

Further, in the present invention, since the refrigeration cycle is divided into a plurality of parts, the capacity control of the compressors of the individual refrigeration cycles can be performed separately according to each heat load. It is possible to easily cope with temperature changes due to flow rate fluctuations of the secondary side heat medium. Moreover, liquids, such as water, or gas, such as air, can be used for a secondary side heat carrier.
If a plurality of compressors, condensers, and evaporators are modularized, their design and manufacture can be facilitated. If a general-purpose integrated unit is used, design, manufacture and construction can be greatly reduced.

  As an embodiment of the present invention, as shown in FIG. 1, when a condenser group is integrally formed and a variable internal volume ratio type compressor is used, the shaft power of each compressor is made uniform. If the internal volume ratio of each compressor is made to vary in the direction from one side to the final stage, the optimum compression ratio can be achieved when multiple compressors are connected to a single drive shaft of the drive motor. Accordingly, there is an advantage that the power reduction based on the motor can be performed, the load balance is kept good, and the torque fluctuation of the electric motor is reduced.

  FIG. 4 shows an example of the compression ratio and the internal volume ratio when three compressors are connected to a single drive shaft. By adopting a compressor with an internal volume ratio suitable for operating conditions, power can be reduced. Since the compression ratio differs depending on the evaporation temperature of each refrigeration cycle, a compressor with the same internal volume ratio loses due to over-compression or under-compression, and the merits of three cascades are offset. Therefore, it is important to select the optimum internal volume ratio for each compressor.

In the present invention, preferably, a low-stage compressor and a high-stage compressor integrated as a single-stage two-stage compressor may be cascaded as single-stage machines. As a result, components such as couplings and gears can be reduced, and the overall structure can be made compact.
Furthermore, two adjacent compressors face each other, a drive motor is arranged between the compressors, and these two compressors are connected to both ends of a single drive shaft of the drive motor. Then, space saving can be achieved similarly.

FIG. 5 and FIG. 6 are diagrams for illustrating a power reduction situation when two adjacent compressors are connected to a single drive shaft as a single-unit or two-stage compressor as described above.
When two compressors are connected, the capacity ratio of 1st (first unit) and 2nd (second unit) can be considered in various combinations as shown in FIG. If 7 is shared by TE1 and 3 is shared by TE2, when considered simply, the area S = 3 × 7 = 21, which is simulated as a reduced power portion.

  As a result, as shown in FIG. 5, it can be seen that 1st: 5 is the maximum reduction area, and the capacity when two units are cascaded is 1st = 5, 2nd = 5, and 1: 1 is optimal. . Further, as can be seen from FIG. 5, it is found that the power reduction is remarkable when the capacity ratio between 1st and 2nd is from 3: 7 to 7: 3.

Further, as one embodiment of the integrated condenser, an integrated evaporative condenser in which a container main body forming a sprinkling tank is integrated, and the refrigerant pipe of the refrigeration cycle is separately disposed in the watering region of the container main body. For example, it is possible to lower the condensation temperature as compared with the case where a general cooling tower is used as the condenser, thereby improving the coefficient of performance COP of the refrigeration cycle.
In addition, by using a single condenser for each of a plurality of refrigeration cycles, when a natural refrigerant such as ammonia is used as a refrigerant, it can be structured to prevent a large amount of leakage even if ammonia leaks. Even when a flammable HC refrigerant is used, it can be easily ventilated with a single fan.

  As another embodiment of the present invention, at least one of the plurality of refrigeration cycles includes a high-source refrigeration cycle in which a high-source refrigerant on a high-temperature side flows and a low-source refrigeration cycle in which a low-source refrigerant on a low-temperature side flows. You may make it comprise the multi-component refrigeration cycle combined with the cascade condenser which absorbs latent heat of evaporation by a high original refrigerant, cools and liquefies.

  FIG. 7 is an explanatory diagram schematically showing this configuration. In FIG. 7, M1 is a multi-component refrigeration cycle in which a high-source refrigeration cycle H1 in which a high-temperature-side high-source refrigerant flows and a low-source refrigeration cycle L1 in which a low-temperature-side low-source refrigerant flows are combined in a cascade condenser G1. In the cascade condenser G1, the low-source refrigerant of the low-source refrigeration cycle L1 absorbs latent heat of evaporation by the high-source refrigerant of the high-source refrigeration cycle H1, and cools and liquefies. The multi-source refrigeration cycles M2 and M3 have the same configuration.

With this configuration, the secondary side heat medium flow path connecting the evaporators E1 to E3 can cool the secondary side heat medium at −60 ° C. to a cryogenic temperature around −100 ° C., and can produce cryogenic heat. In addition, for example, heat of 30 to 45 ° C. can be simultaneously and efficiently manufactured in the secondary heat medium flow path connecting the condensers D1 to D3. Moreover, the cold heat of -40 degreeC--30 degreeC can also be taken out from the low original refrigerant | coolant of cascade condenser G1-G3.
As described above, in the present invention, among a plurality of refrigeration cycles independently arranged in parallel, a part of them is a multi-source refrigeration cycle, and a heat source at a desired temperature can be freely taken out over a wide temperature range from a very low temperature to a high temperature. And thereby a highly efficient heat pump cycle can be realized.

  According to the first configuration of the present invention, the evaporator group constituting the plurality of refrigeration cycles is connected in series with the flow path of the secondary heat medium from one side to the final stage, and the refrigerant suction pressure of each compressor Are set to be sequentially different from the one side to the final stage, and the secondary side heat medium is made to flow in order from the evaporator having a high evaporation pressure to the evaporator having a low evaporation pressure in the secondary heat medium flow path. By configuring it, it is possible to supply cold heat of optimum temperature to various cooling loads in a wide temperature range, and it is possible to reduce the compression ratio of each compressor, so that the compressor power can be reduced, COP can be improved.

  Further, according to the second configuration of the present invention, the condenser group constituting the plurality of refrigeration cycles is connected in series with the flow path of the secondary heat medium from one side to the final stage, and the refrigerant of each compressor The discharge pressure is set to be sequentially changed from one side toward the final stage, and the secondary side heat medium is sequentially flowed from the condenser having a low condensing pressure to the condenser having a high condensing pressure in the secondary heat medium flow path. With this configuration, it is possible to supply the heat at the optimum temperature to various heating loads in a wide temperature range, and it is possible to reduce the compression ratio of each compressor, thereby reducing the compressor power. COP can be improved.

  Further, according to the third configuration of the present invention, the evaporator group and the condenser group constituting the plurality of refrigeration cycles are respectively connected in series from the one side toward the final stage, and the flow path of the secondary side heat medium is connected. The refrigerant suction pressure of each compressor is set to be sequentially changed from one side toward the final stage, and the secondary side heat medium is transferred from the evaporator having a high evaporation pressure to the secondary side heat medium flow path connected to the evaporator. While flowing sequentially toward the evaporator having a low evaporation pressure, the secondary heat medium is sequentially transferred from the condenser having a low condensation pressure to the condenser having a high condensation pressure in the secondary heat medium flow path connected to the condenser. By being configured to flow, it is possible to supply cooling and heating at the optimum temperature to various cooling loads and heating loads in a wide temperature range, and the compression ratio of each compressor can be adjusted in all of the plurality of refrigeration cycles. To reduce the compressor power, It is possible to further improve the COP me.

  If a single-stage two-stage compression low-stage compressor and a high-stage compressor connected to a single drive source are configured to function as single-stage machines, a plurality of compressors are treated as if they were one unit. Since it can be integrated into a unitary unit structure as a compressor, it is possible to save about 10-30% of space in volume, and by designing these units into a unitary unit, designing, manufacturing and construction The time or cost required can be greatly reduced.

  In addition, when the condenser group is configured integrally and a variable internal volume ratio type compressor is used, the internal volume ratio of each compressor is changed from one side to the final stage in a direction to equalize the shaft power of each compressor. If it is configured to be different from each other, when a plurality of compressors are connected to a single drive shaft of a drive motor, power reduction based on an optimal compression ratio is possible, and a good load balance is maintained. There is an advantage that torque fluctuation of the electric motor is reduced.

In addition, if the condenser group is composed of an integral-type evaporative condenser in which the container body forming the watering tank is integrated, and the refrigerant pipe of the refrigeration cycle is separately arranged in the watering area of the container body, a general cooling can be performed. Condensation temperature can be lowered compared to the case of using a tower, thereby reducing the COP of the refrigeration cycle, and by integrating it, it can be compactly integrated, and designing and manufacturing are facilitated. .

In addition, by using an integrated evaporative condenser, ammonia, which is a natural refrigerant, is used as a refrigerant. There is an advantage that it is easy to take a leakage prevention measure.
In addition, when two compressors are connected to a single drive shaft, a large power reduction can be achieved by changing the capacity distribution to both compressors from 3: 7 to 7: 3.

  Preferably, at least one of the plurality of refrigeration cycles is divided into a high-source refrigeration cycle in which a high-temperature-side high-source refrigerant flows and a low-source refrigeration cycle in which a low-temperature-side low-source refrigerant flows. If a multi-component refrigeration cycle is combined with a cascade condenser that absorbs and cools and liquefies, it becomes possible to produce a very low temperature secondary heat medium of minus 60 ° C. to minus 100 ° C. As the side heat medium, for example, heat of 30 to 45 ° C. can be produced simultaneously and with high efficiency.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the present invention to that only, unless otherwise specified.
FIG. 8 is a block diagram showing the first embodiment of the present invention, FIG. 9 is a block diagram showing the second embodiment of the present invention, FIG. 10 is a block diagram showing the third embodiment of the present invention, and FIG. FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention.

  The first embodiment of the present invention relates to a two-stage cascade heat pump system chiller unit using a single-stage two-stage compressor driven coaxially. In FIG. 8, the compressor 3 and the compressor 4 are driven sources ( An electric motor or the like) is connected to a single drive shaft of 5 to form a coaxial integrated single-unit two-stage compressor unit 6 that operates simultaneously. The compressor 4, the condenser 10, the expansion valve 11, and the evaporator 7 constitute a single independent first refrigeration cycle R <b> 1 connected by the refrigerant circulation flow path 13, and flow through the flow path 1 by the evaporator 7. Heat is absorbed from the cooling secondary heat medium (for example, water), and the condensation heat is discharged to the heating (heat radiation) secondary heat medium flowing through the flow path 2 by the condenser 10.

At the same time, the compressor 3, the condenser 9, the expansion valve 12, and the evaporator 8 constitute a single independent second refrigeration cycle R <b> 2 connected by the refrigerant circulation flow path 14. Heat is absorbed from the cooling secondary medium (for example, water) that flows through the condenser 9, and the condensation heat is discharged to the heated secondary heat medium that flows through the flow path 2 by the condenser 9.
The cooling secondary heat medium is cooled in the first stage by the evaporator 7 and then further cooled in the second stage by the evaporator 8 in which the flow path 1 is arranged in series.

On the other hand, the heating secondary heat medium receives the first stage condensation heat by the condenser 9 in the direction opposite to the flow of the cooling secondary medium 1, and then the flow path 2 is arranged in series. The condenser 10 receives the second stage condensation heat.
Each device having the above configuration is integrally manufactured as an integrated chiller unit 15.

  According to the first embodiment having such a configuration, a single machine driven by a single drive shaft of a drive source (such as an electric motor) 5 as compared with a conventional heat pump chiller unit in which a single refrigeration cycle is constituted by a single stage compressor. By using a two-stage compressor, the separate arrangement of two compressors and drive source combinations can be combined into a single unit structure as a single compressor. Space becomes possible.

Further, by making the single-unit two-stage compressor into an integrated unit, it can be manufactured and constructed as a general-purpose integrated unit, and the time and equipment cost required for manufacturing and construction are greatly reduced.
Further, in this example, the cooling temperature difference example Δt = 10 ° C. to 30 ° C. of the cooling secondary side heat medium (water) 1 and the heating temperature difference example Δt = 10 to 10 ° C. to 30 ° C. It is possible to produce 30 ° C heat at the same time, and by making the cascade heat pump chiller of this embodiment a general-purpose machine, it can be used for air conditioning and other heating / cooling loads, especially industrial cold / hot process plus-minus temperature When producing a heat source in a wide temperature range, it is possible to improve the COP by about 20 to 50% compared to the prior art.

  For example, FIG. 12 shows a case where the conventional system in the case of heating and cooling the secondary side heat medium (water) at a temperature difference of 20 ° C. with a single-stage refrigerator and the COP in the cooling of the present invention are compared. In the figure, (a) shows a conventional one-stage heating / cooling system, and (b) shows a two-stage cascade heating / cooling according to the first embodiment of the present invention. As shown in FIG. 12, the COP of the present invention is improved, and can be reduced by 23% compared to the conventional method in terms of power.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is an embodiment relating to a two-stage cascade heat pump chiller unit in which two single-stage compressors are connected and driven by a drive machine (electric motor) having both drive shaft ends. In FIG. Reference numeral 3 'and compressor 4' each denote a single single-stage compressor, and a tandem drive type compressor unit 6 'that is connected to both shaft ends of a single shaft end drive unit 5' and is operated simultaneously. Form.
Since the structure of other parts is the same as that of the first embodiment, the same parts are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  According to the second embodiment having such a configuration, as in the first embodiment, the conventional arrangement in which the compressor and the drive source are separately arranged in two units has a compressor at both shaft ends of one drive source 5 ′. By connecting 3 ′ and the compressor 4 ′, a space saving of about 10 to 30% in volume can be achieved. The other two compressors are produced and constructed as a general-purpose integrated unit, and the same operational effects as the first embodiment are achieved, such as reduction in construction cost and improvement of COP.

  When comparing the single-unit two-stage compressor unit 6 of the first embodiment with the tandem drive type compressor unit 6 ′ of the second embodiment, when the compressor unit 6 of the first embodiment is a complete direct coupling type, the coupling The tandem drive type compressor unit 6 ′ according to the second embodiment, on the other hand, requires only one sealing device and a bearing, etc., and the above-mentioned components are separately required for the two compressors. The compressor unit 6 reduces both occupied space, weight and cost.

  Next, a third embodiment of the present invention will be described with reference to FIG. The present embodiment relates to a cascade type heat pump chiller unit incorporating an integrated condenser. In FIG. 10, the compressor 25, the drive source 28, the condensation heat exchanger 22, the expansion valve 37, and the evaporator 31 are refrigerant circulation. Connected by the flow path 34 to form a single independent first refrigeration cycle R1, and the evaporator 31 is connected to the secondary heat medium flow path 21 to absorb heat from the cooling secondary heat medium and condense. Heat is dissipated by the heat exchanger 22.

The compressor 26, the drive source 29, the condensing heat exchanger 23, the expansion valve 38, and the evaporator 32 are connected by a refrigerant circulation channel 35 to constitute a single independent second refrigeration cycle R <b> 2. The cooling secondary side heat medium flow path 21 is connected to 32 and absorbs heat from the secondary side heat medium, and is radiated by the condensation heat exchanger 23.
Further, the compressor 27, the drive source 30, the condensing heat exchanger 24, the expansion valve 39, and the evaporator 33 are connected by a refrigerant circulation flow path 36 to constitute a single independent third refrigeration cycle R3 and evaporate. The cooling secondary side heat medium flow path 21 is connected to the vessel 33 to absorb heat from the secondary side heat medium and radiate heat by the condensation heat exchanger 24. A cooling secondary side heat medium flow path 21 is connected in series to the evaporators 31 to 33 of each refrigeration cycle, and the secondary side heat medium flows from the evaporator 31 having a high evaporation pressure (compressor suction pressure) to the low side. It is configured to flow.

The condensing heat exchanger 22, the condensing heat exchanger 23, and the condensing heat exchanger 24 are an integrated evaporative condenser that includes a watering pump 45, a watering pipe 41, an air inlet 42, an exhaust fan 43, and cooling water 44. 25 is disposed inside.
The cooling secondary heat medium (water) 21 is cooled by the evaporator 30 in the first stage, then cooled in the second stage by the evaporator 32 arranged in series, and further cooled by the evaporator 33 arranged in series. Stage cooling is performed. The integrated chiller unit 46 composed of the above devices is manufactured and constructed integrally.

  In the third embodiment, since the condensers are integrally formed, the discharge pressures of the compressors 25 to 27 are the same. By setting the suction pressures of these compressors in a stepped manner, the compressors of the compressors are compressed. The ratio can be smaller than when operating with a single refrigeration cycle. Since the compression ratios of the compressors 25 to 27 are different from each other in this way, the internal volume ratios of the compressors are made different to make the shaft power of these compressors uniform. Thereby, the load balance of these compressors can be kept good. Further, when these compressors are connected to a single drive shaft of a drive motor, there is an advantage that torque fluctuation of the motor is reduced.

  According to the third embodiment having such a configuration, when the cooling water of the refrigeration cycle is conventionally cooled from 37 ° C. to 32 ° C. by a general cooling tower, the condensation temperature of the refrigeration cycle is estimated to be about 40 ° C. to 42 ° C. However, when an evaporative condenser is used, the temperature is generally set to 35 ° C. In this embodiment, since the evaporating condenser 41 is incorporated, the condensing temperature is lowered. COP is improved by about 10%.

  In addition, by taking advantage of the energy saving effect of the evaporative condenser 40 and by increasing the cooling temperature difference of the cooling secondary side heat medium 21, cascade operation is performed in series with a plurality of refrigeration cycles R1, R2, and R3. The energy saving effect of the cooling performance is synergistic, and it is possible to improve the COP (coefficient of performance) by about 10 to 20% as compared with a heat pump chiller using a water-cooled condenser conventionally used alone.

  Furthermore, as a third embodiment of the present invention, FIG. 13 shows an example in which the COP of the conventional method is compared with the case where the temperature difference Δt = 20 ° C. or more of the inlet and outlet of the secondary side cooling medium. In FIG. 13, (a) shows a conventional cooling method, and (b) shows a three-stage cascade cooling method according to the third embodiment of the present invention. As shown in (b), the COP is significantly improved in the present invention, and is reduced by 37% in terms of electric power.

In addition, since the integrated evaporator 40 is used, even when toxic ammonia is used as a refrigerant, the leak point can be limited to only the exhaust fan 43, and even if an ammonia leak occurs. Leakage of ammonia outside the machine can be easily prevented.
Moreover, manufacturing, construction, etc. can be significantly reduced by using an integrated unit structure as a general-purpose unit in the present embodiment.

  Next, a fourth embodiment of the present invention will be described with reference to FIG. This embodiment relates to a cascade heat pump chiller unit in which a plurality of binary refrigeration cycles are arranged in series. In FIG. 11, a low-source compressor 56, a drive source 57, a cascade condenser 59, an expansion valve 60, and an evaporator 58 are The low secondary side single refrigeration cycle is configured, the cooling secondary heat medium passage 51 is connected to the evaporator 58, absorbs heat from the cooling secondary heat medium, and the cascade condenser 59 reduces the low original side refrigeration. The heat of condensation in the cycle is discharged.

  Further, the high-source compressor 62, the drive source 63, the condenser 64, the expansion valve 65, and the cascade condenser 59 form a single high-side refrigeration cycle, and the cascade condenser 59 generates the condensation heat of the low-source side refrigeration cycle. The heating (heat radiation) secondary side heat medium flow path 52 is connected to the condenser 64, and the condensation heat of the high-source side refrigeration cycle is discharged to the heating (heat radiation) secondary side heat medium flow path. The combination of the low element side and the high element side constitutes a single first binary refrigeration cycle 53.

  On the other hand, the low-source compressor 67, the drive source 68, the cascade condenser 70, the expansion valve 71, and the evaporator 69 constitute a low-source-side single refrigeration cycle. Are connected to absorb the heat from the cooling secondary medium, and the low-side condensation heat is discharged by the cascade condenser 70. Further, the high-source compressor 73, the drive source 74, the condenser 75, the expansion valve 76, and the cascade condenser 70 form a high-source-side single refrigeration cycle, and the cascade condenser 70 condenses heat of the low-source-side refrigeration cycle. Is connected to the heating (heat radiation) secondary side heat medium flow path 52 by the condenser 75, and the condensation heat of the high-side refrigeration cycle is discharged to the heating (heat radiation) secondary side heat medium. The combination of the low element side and the high element side constitutes a single second binary refrigeration cycle 54.

The cooling secondary heat medium 51 is cooled in the first stage by the evaporator 58 of the first binary refrigeration cycle 53, and then in two stages by the evaporator 69 of the second binary refrigeration cycle 54 arranged in series. The eyes are cooled. The heated secondary heat medium 52 is heated by the condenser 64 of the first binary refrigeration cycle 53 and then heated by the condenser 75 of the second binary refrigeration cycle 54 arranged in series after the first stage heating. Stage heating is performed. The fourth embodiment having such a configuration is manufactured and constructed as an integrated unit structure 77.
In addition, in FIG. 7, the temperature value of the secondary side heat medium or refrigerant | coolant in each site | part is shown as an example.

  According to the fourth embodiment, in the cooling secondary heat medium flow channel 51, an extremely low temperature secondary heat medium having an outlet temperature of −80 to −100 ° C. is produced from the secondary heat medium having an inlet temperature of −60 ° C. At the same time, in the heating secondary heat medium flow path 52, a high temperature secondary heat medium having an outlet temperature of 45 ° C. can be produced from the secondary heat medium having an inlet temperature of 20 ° C.

As described above, a plurality of binary refrigeration cycles are cascaded in series, so that the COP (coefficient of performance) can be improved by several percent compared to the case where a conventional single binary refrigeration cycle system is applied.
In addition, the cascade condensers 59 and 70 can produce -20 [deg.] C. and -40 [deg.] C. cooling sources, respectively, and thus can supply the cooling sources to various cooling loads.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to obtain a cold source and a thermal source with a large temperature difference at the inlet and outlet of the system, it is possible to supply a variety of cooling loads or heating loads in a wide temperature range. In addition, the power of the heat pump system can be reduced, and the coefficient of performance COP can be significantly improved.

FIG. 1A is a schematic diagram showing an embodiment according to the first configuration of the present invention, and FIG. 1B is a schematic diagram showing a conventional refrigeration cycle. FIG. 2A is a schematic diagram showing an embodiment according to the second configuration of the present invention, and FIG. 2B is a schematic diagram showing a conventional refrigeration cycle. It is a diagram which shows the relationship between refrigerant | coolant temperature and COP. It is a table | surface which shows the example of a compression ratio at the time of connecting three compressors to a single drive shaft, and an internal volume ratio. It is a diagram which shows the power reduction condition at the time of connecting two adjacent compressors to a single drive shaft. It is a PT diagram showing a power reduction situation when two adjacent compressors are connected to a single drive shaft. It is a schematic diagram which shows one form concerning the 3rd structure of this invention. It is a block diagram which shows 1st Example of this invention. It is a block diagram which shows 2nd Example of this invention. It is a block diagram which shows 3rd Example of this invention. It is a block diagram which shows 4th Example of this invention. It is explanatory drawing which shows the COP improvement rate by 1st Example of this invention. It is explanatory drawing which shows the COP improvement rate by 3rd Example of this invention.

Explanation of symbols

1,21,51 Secondary heat medium flow path 2,52 Heating (heat radiation) secondary heat medium flow path 3,3 ', 4,4', 25,26,27 Compressor 5,28,29,30 , 57, 63, 68, 74 Compressor drive source 6 Single-unit two-stage compressor unit 6 'Tandem drive type compressor unit 7, 8, 32, 32, 58, 69 Evaporator 9, 10, 64, 75 Condenser 11 , 12, 37, 38, 39, 60, 65, 71, 76 Expansion valve 15, 46, 77 Integrated chiller unit 40 Evaporative condenser 53 First two-way refrigeration cycle 54 Second two-way refrigeration cycle 59, 70 Cascade Condensers 56, 67 Low original compressor 62, 73 High original compressor R1 First refrigeration cycle R2 Second refrigeration cycle R3 Third refrigeration cycle

Claims (9)

In a cascade heat pump system in which a plurality of refrigeration cycles each having a compressor, a condenser, an expander and an evaporator are arranged in parallel,
The flow path of the secondary side heat medium is connected in series from one side to the final stage to the evaporator group constituting the plurality of refrigeration cycles,
Set the refrigerant suction pressure of each compressor in order from one side to the last stage,
A cascade-type heat pump system, wherein the secondary heat medium is caused to flow through the secondary heat medium flow path in order from an evaporator having a high evaporation pressure toward an evaporator having a low evaporation pressure. In a cascade heat pump system in which a plurality of refrigeration cycles each having a compressor, a condenser, an expander and an evaporator are arranged in parallel,
The flow path of the secondary side heat medium is connected in series from one side to the final stage to the condenser group constituting the plurality of refrigeration cycles,
Set the refrigerant discharge pressure of each compressor in order from the one side to the final stage,
A cascade-type heat pump system, wherein the secondary heat medium flows in the secondary heat medium flow path in order from a condenser having a low condensation pressure to a condenser having a high condensation pressure. In a cascade heat pump system in which a plurality of refrigeration cycles each having a compressor, a condenser, an expander and an evaporator are arranged in parallel,
The flow path of the secondary side heat medium is connected in series from one side to the final stage to the evaporator group and the condenser group constituting the plurality of refrigeration cycles,
Set the refrigerant suction pressure of each compressor in order from one side to the last stage,
The secondary side heat medium flows in the secondary side heat medium flow path connected to the evaporator in order from an evaporator having a high evaporation pressure to an evaporator having a low evaporation pressure, and the secondary side heat medium connected to the condenser. A cascade type heat pump system configured to flow a secondary heat medium in a medium flow path in order from a condenser having a low condensation pressure to a condenser having a high condensation pressure.   In the internal volume ratio variable type compressor, the condenser group is integrally formed, and the internal volume ratio of each compressor is made different from one side toward the final stage in a direction to make the shaft power of each compressor uniform. The cascade heat pump system according to claim 1, wherein the cascade heat pump system is configured as described above.   The condenser group is constituted by an integral-type evaporative condenser in which a container main body forming a sprinkling tank is integrated, and refrigerant pipes of the refrigeration cycle are separately arranged in the water sprinkling region of the container main body. Item 5. The cascade heat pump system according to Item 1 or 4. The single-stage two-stage compression low-stage compressor and the high-stage compressor connected to a single drive source each function as a single-stage machine. Cascade type heat pump system.   Two adjacent compressors arranged in parallel face each other, a drive motor is arranged between the compressors, and the two compressors are connected to a single drive shaft of the drive motor. The cascade heat pump system according to any one of claims 1 to 3, wherein   The cascade type heat pump system according to claim 1, wherein a single natural refrigerant is used for the plurality of refrigeration cycles.   At least one of the plurality of refrigeration cycles includes a high-source refrigeration cycle in which high-temperature side high-source refrigerant flows and a low-source refrigeration cycle in which low-temperature side low-source refrigerant flows. The cascade heat pump system according to claim 1, wherein the cascade heat pump system is configured by a multi-source refrigeration cycle combined with a cascade condenser that cools and liquefies.

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