JP2016109010A - Refrigeration waste heat recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration waste heat recovery system capable of achieving high efficiency by simple control while ensuring compactness by sharing a part of a Rankine cycle circuit and a refrigeration cycle circuit.SOLUTION: A refrigeration waste heat recovery system includes a Rankine cycle circuit and a refrigeration cycle circuit sharing a condensing portion composed of first and second condensers arranged in series, pressure detecting means for detecting a downstream-side fluid pressure of the condensing portion, flow channel determination means for determining an optimum flow channel in the condensing portion on the basis of the difference of a first threshold value corresponding to a pump of the Rankine cycle circuit and a second threshold value corresponding to a second evaporator of the refrigeration cycle circuit, and the detection value, and flow channel control means for controlling the flow channel to realize the optimum flow channel.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a refrigeration waste heat recovery system including a Rankine cycle and a refrigeration cycle.

  2. Description of the Related Art A vehicle equipped with a Rankine cycle circuit that converts waste heat of an engine, which is a power source, into electric energy and recovers it, and a refrigeration cycle circuit for purposes such as air conditioning, is known. For example, Patent Document 1 discloses a technology for reducing the number of parts and reducing the size of the system by sharing a part of the circulation circuit included in each of the Rankine cycle circuit and the refrigeration cycle circuit in this type of vehicle. Has been.

JP 2013-217340 A

However, in Patent Document 1, there is a problem that the cycle efficiency in the Rankine cycle circuit and the refrigeration cycle circuit is likely to be reduced by sharing a part of the circulation circuit. For example, if the Rankine cycle circuit is preferentially controlled, the efficiency of the refrigeration cycle circuit is likely to be reduced. Conversely, if the refrigeration cycle circuit is preferentially controlled, the efficiency of the Rankine cycle circuit is likely to be reduced.
In particular, when the ambient environment (for example, temperature or humidity) changes, it is required to control the Rankine cycle circuit and the refrigeration cycle circuit according to the change state. Is difficult to control.

  In view of the above circumstances, at least one embodiment of the present invention is a refrigeration capable of achieving good efficiency with simple control while ensuring compactness by sharing a part of the Rankine cycle circuit and the refrigeration cycle circuit. The purpose is to provide a waste heat recovery system.

  A refrigeration waste heat recovery system according to at least one embodiment of the present invention includes a first condenser and a condenser having a second condenser arranged in series with the first condenser, and a refrigerant flow path flowing through the condenser. A Rankine cycle circuit including a flow path switching unit to be switched, a first evaporator, a first expander, and a pump, wherein a first threshold value that is a desired fluid pressure in a downstream flow path of the condensing unit is set in advance; By connecting to the upstream inlet and downstream outlet of the condensing unit respectively, the condensing unit is shared, and the second fluid, the second expander and the compressor are provided, and the desired fluid in the downstream channel of the condensing unit A refrigeration cycle circuit in which a second threshold value that is a pressure is set in advance; pressure detecting means for detecting fluid pressure downstream of the condensing unit and upstream of the pump and the second evaporator; and the first Threshold and said first Based on the difference between the threshold value and the fluid pressure detected by the pressure detection means, the flow path determination means for determining the optimal flow path in the condensing part, and the condensing part has the optimal flow path, And a flow path control means for controlling the flow path switching unit.

  According to this configuration, the Rankine cycle circuit and the refrigeration cycle circuit partially share the flow path including the condensing part, thereby having excellent compactness and being easily mountable on a vehicle. The condensing part includes a first condenser and a second condenser arranged in series with each other, and the capacity of the condensing part is variably configured by switching control of the flow path switching part. The flow path switching unit is controlled so as to obtain an optimal flow path that is determined based on the difference between the first threshold value and the second threshold value and the fluid pressure on the upstream side of the pump and the second evaporator. Thereby, the capacity | capacitance of a condensation part can be optimized according to ambient environment (for example, temperature and humidity), and favorable efficiency is obtained.

  In particular, since the first condenser and the second condenser constituting the condenser are arranged in series with each other, the flow rates at the outlet of the first condenser and the outlet of the second condenser are the same. Therefore, the flow rate can be controlled more easily than when these condensers are arranged in parallel. As a result, the flow path switching control can be performed with a simple control logic with high accuracy in accordance with changes in the surrounding environment.

  According to at least one embodiment of the present invention, a refrigeration waste heat recovery system capable of achieving good efficiency with simple control while ensuring compactness by sharing a part of a Rankine cycle circuit and a refrigeration cycle circuit. Can be provided.

It is a mimetic diagram showing the composition of the frozen waste heat recovery system concerning one embodiment of the present invention. It is a flowchart which shows the control content of the refrigeration waste heat recovery system of FIG. It is a time chart of the fluid pressure in the 1st bypass line of the refrigeration waste heat recovery system of Drawing 1, and the 2nd bypass line.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
In addition, for example, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within the range where the same effect can be obtained. A shape including a chamfered portion or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a schematic diagram showing a configuration of a refrigeration waste heat recovery system 1 according to an embodiment of the present invention, FIG. 2 is a flowchart showing control contents of the refrigeration waste heat recovery system 1 of FIG. 1, and FIG. It is a time chart of the fluid pressure in the 1st bypass line 24a and the 2nd bypass line 24b of the refrigeration waste heat recovery system 1 of FIG.

  The refrigeration waste heat recovery system 1 is mounted on a vehicle (not shown) including an engine 2 as a power source. The engine 2 is an internal combustion engine that can output power by burning fossil fuels such as gasoline and light oil, and a four-cylinder engine is illustrated in FIG. The engine 2 includes a cooling water circuit 3. On the cooling water circuit 3, a circulation pump 4 for pumping the cooling water and a radiator 5 for radiating heat by exchanging heat between the cooling water and the outside air are provided. The radiator 5 is configured to be blown by a fan 6 that is driven using a part of the power of the engine 2 so that heat dissipation can be promoted.

  A bypass circuit 7 is branched from the cooling water circuit 3. The cooling water flowing through the bypass circuit 7 is cooled by heat exchange with the fluid flowing through the Rankine cycle circuit 10 in the first evaporator 11 constituting the Rankine cycle circuit 10. That is, the waste heat energy contained in the cooling water is recovered by the Rankine cycle circuit 10.

  The Rankine cycle circuit 10 includes a first evaporator 11, a first expander 12, a condensing unit 13, and a pump 14. The fluid flowing through the Rankine cycle circuit 10 is evaporated (vaporized) by the first evaporator 11 and then expanded by the first expander 12. In the first expander 12, the turbine is driven when the fluid is expanded, and the generator 16 connected to the rotating shaft 15 of the turbine is driven. The expanded fluid is condensed (liquefied) by the condensing unit 13 and then returned to the first evaporator 11 by being pumped by the pump 14.

  The generator 16 generates power according to the driving state. The electric energy obtained by the power generation is consumed by various loads or stored in a battery (not shown) via an inverter.

  The Rankine cycle circuit 10 configured as described above is designed so that the fluid pressure of each part falls within a predetermined range. In the present embodiment, in particular, the upper limit value (desired fluid pressure) of the range in which the fluid pressure in the flow path between the condensing unit 13 and the pump 14 should be set is set in advance as the first threshold value P1.

  The refrigeration cycle circuit 20 shares the Rankine cycle 10 and the condensing unit 13 by being connected to the upstream inlet and the downstream outlet of the condensing unit 13, respectively. The refrigeration cycle circuit 20 includes a second evaporator 21 and a compressor 22. The fluid condensed (liquefied) in the condensing unit 13 is evaporated in the second evaporator 21. The second evaporator 21 is configured to be able to exchange heat between the fluid flowing through the refrigeration cycle circuit 20 and the outside air, and cools the outside air by absorbing heat from the outside air when the fluid is vaporized. The fluid evaporated by the second evaporator 21 is compressed by the compressor 22 and then condensed again by the condensing unit 13.

  The refrigeration cycle circuit 20 configured as described above is designed so that the fluid pressure of each part falls within a predetermined range. In the present embodiment, in particular, the upper limit (desired fluid pressure) of the range in which the fluid pressure in the flow path between the condenser 13 and the second evaporator 21 is to be taken is set in advance as the second threshold value P2.

  The first threshold value P1 and the second threshold value P2 may be different from each other or may be the same as each other. However, in the present embodiment, the first threshold value P1 is set to be larger than the second threshold value P2. The case (ie, P1> P2) is illustrated.

  The condensing unit 13 includes a first condenser 13a and a second condenser 13b arranged in series with the first condenser 13a. In the example of FIG. 1, the first condenser 13a has a larger capacity than the second condenser 13b.

  The flow path of the refrigerant flowing through the condensing unit 13 is configured to be switched by the flow path switching unit 23. The flow path switching unit 23 includes a first bypass line 24a connected in parallel to the first condenser 13a by switching valves 25a and 25b provided on the upstream side and the downstream side of the first condenser 13a, and a second And a second bypass line 24b connected in parallel to the second condenser 13a by switching valves 25c and 25d provided on the upstream side and the downstream side of the condenser 13b, respectively.

The switching valves 25a to 25d are valve mechanisms such as three-way valves. The switching valve 25a is configured such that the fluid supplied from the upstream side is supplied to at least one of the first bypass line 24a and the first condenser 13a according to the switching state. The switching valve 25b is configured such that fluid supplied from at least one of the first bypass line 24a and the first condenser 13a flows toward the switching valve 25c according to the switching state.
The switching valve 25c is configured such that the fluid supplied from the switching valve 25b side is supplied to at least one of the second bypass line 24b and the second condenser 13b according to the switching state. The switching valve 25d is configured such that the fluid supplied from at least one of the second bypass line 24b and the second condenser 13b flows downstream according to the switching state.

  On the downstream side of the condensing unit 13 and the upstream side of the pump 14 and the second evaporator 21, pressure detection means 30 for detecting the fluid pressure flowing through the flow path is installed. The pressure detection unit 30 is, for example, a pressure sensor that can transmit a detection value as an electrical signal, but the mode is not limited as long as the fluid pressure can be detected.

In the present embodiment, the Rankine cycle circuit 10 and the refrigeration cycle circuit 20 use fluids that are common to each other. The fluid is a known refrigerant such as R134a (CH ₂ FFCCF ₂ ). Such a fluid functions as a working fluid in the Rankine cycle circuit 10 and also functions as a refrigerant in the refrigeration cycle circuit 20.

The control unit 40 is a control unit that performs control of the refrigeration waste heat recovery system 1, and is configured by, for example, an electronic calculator. The control unit 40 acquires the detection value from the pressure detection unit 30, and controls the flow path switching unit 23 by switching the switching valves 25a to 25d based on the detection value. The control unit 40 includes a storage unit 41 that stores various types of information necessary for performing control described later, a flow path determination unit (flow path determination unit) 42 that determines an optimal flow path in the condensing unit 13, and a flow path. A flow path control unit (flow path control means) 43 that controls the flow path switching unit 23 so as to realize the optimum flow path determined by the determination unit 42 is provided.
The storage unit 41 is composed of a storage medium such as a memory or a hard disk, and stores the first threshold value and the second threshold value in a readable manner.

  Then, with reference to FIG.2 and FIG.3, the control content of the refrigeration waste heat recovery system 1 by the control part 40 is demonstrated. In FIG. 3, a route selected as a flow path is indicated by a thick line, and a route not selected as a flow path is indicated by a broken line.

  The control unit 40 acquires the first threshold value P1 and the second threshold value P2 necessary for the main control from the storage unit 41 (step S1), and acquires the detection value P from the pressure detection unit 30 (step S2). The flow path determination unit 42 determines the optimal flow path of the condensing unit 13 based on the difference between the first threshold value P1 and the second threshold value P2 acquired as described above and the detected value P.

  First, the flow path determination unit 42 determines whether or not the detection value P is greater than the first threshold value P1 (step S3). When the detected value P is larger than the first threshold value P1 (step S3: YES), the flow path determination unit 42 causes the fluid to flow only in the second condenser 13b having a small capacity among the first condenser 13a and the second condenser 13b. The flow path (that is, the route passing through the first bypass line 24a and the second condenser 13b) is selected as the optimal flow path (step S4). In other words, when P> P1> P2, an amount of fluid sufficient for both the Rankine cycle circuit 10 and the refrigeration cycle circuit 20 is condensed, so that the optimum flow is set to minimize the capacity of the condensing unit 13. A path is determined (see FIG. 3A).

  When the detected value P is less than or equal to the first threshold value P1 (step S3: NO), the flow path determination unit 42 further determines whether or not the detected value P is greater than the second threshold value P2 (step S5). When the detected value P is greater than the first threshold value P2 (step S5: YES), the flow path determination unit 42 causes the fluid to flow only in the first condenser 13a having a large capacity among the first condenser 13a and the second condenser 13b. The flow path (that is, the route passing through the first condenser 13a and the second bypass line 24b) is selected as the optimal flow path (step S6). That is, when P1 ≧ P> P2, a sufficient amount of fluid is condensed for the refrigeration cycle circuit 20, but a sufficient amount of fluid is not condensed for the Rankine cycle circuit 10 side. The optimum flow path is determined so as to increase the capacity of the condensing unit 13 as compared with the case of step S4 (see FIG. 3B).

  When the detected value P is equal to or less than the first threshold value P2 (step S5: NO), the flow path determination unit 42 is a flow path in which fluid flows through both the first condenser 13a and the second condenser 13b (that is, the first and first flow paths). 2) is selected as the optimum flow path (step S7). That is, when P1> P2 ≧ P, it is assumed that a sufficient amount of fluid for both the Rankine cycle circuit 10 and the refrigeration cycle circuit 20 is not condensed, and the capacity of the condensing unit 13 is larger than that in step S6. The optimum flow path is determined so as to further increase (see FIG. 3C).

  Thus, when the optimum flow path is determined in steps S4, S6, and S7, the flow path control means 43 sets the flow path switching units 13c1 and 13c2 so that the condensing unit 13 has the determined optimal flow path. Control (S8). Thereby, the capacity | capacitance of the condensation part 13 is optimized and the efficiency improvement of a refrigeration waste heat recovery system is achieved.

  In the present embodiment, the first condenser 13a has a larger capacity than the second condenser 13b as shown in FIG. 1, but the first condenser 13a and the second condenser 13b are configured to have the same capacity. May be. In this case, since the capacities of the case where only the first condenser 13a is operated and the case where only the second condenser 13b are operated are equal, the capacity of the condenser 13 is variable in two stages (the above-described implementation). In the embodiment, the capacity of the case where only the first condenser 13a is operated is different from the case where only the second condenser 13b is operated, which is advantageous in that the capacity of the condenser 13 is variable in three stages. ).

  As described above, according to the present embodiment, the Rankine cycle circuit 10 and the refrigeration cycle circuit 20 partially share the flow path including the condensing unit 13, thereby having excellent compactness. Can be easily mounted. The condensing unit 13 includes a first condenser 13 a and a second condenser 13 b arranged in series with each other, and the capacity of the condensing unit 13 is configured to be variable by switching control of the flow path switching unit 23. The flow path switching unit 23 switches so as to obtain an optimal flow path determined based on the difference between the first threshold value P1 and the second threshold value P2 and the fluid pressure on the upstream side of the pump 14 and the second evaporator 21. Be controlled. Thereby, the capacity | capacitance of the condensation part 13 can be optimized according to surrounding environment (for example, temperature and humidity), and favorable efficiency is obtained.

  In particular, since the first condenser 13a and the second condenser 13b constituting the condenser 13 are arranged in series with each other, the flow rates at the outlet of the first condenser 13a and the outlet of the second condenser 13b are the same. become. Therefore, it is easier to control the flow rate than when these condensers 13a and 13b are arranged in parallel. As a result, the flow path switching control can be performed with a simple control logic with high accuracy in accordance with changes in the surrounding environment.

  As a result, it is possible to provide the refrigeration waste heat recovery system 1 that can achieve good efficiency with simple control while ensuring compactness by sharing a part of the Rankine cycle circuit 10 and the refrigeration cycle circuit 20.

  The present disclosure can be used for a refrigeration waste heat recovery system including a Rankine cycle and a refrigeration cycle.

DESCRIPTION OF SYMBOLS 1 Refrigeration waste heat recovery system 2 Engine 3 Cooling water circuit 4 Circulation pump 5 Radiator 6 Fan 7 Bypass circuit 10 Rankine cycle circuit 11 1st evaporator 12 1st expander 13 Condensing part 14 Pump 15 Rotating shaft 16 Generator 20 Refrigeration cycle Circuit 21 Second evaporator 22 Compressor 23 Channel switching unit 24a First bypass line 24b Second bypass line 25 Switching valve 30 Pressure detection unit 40 Control unit 41 Storage unit 42 Channel determination unit 43 Channel control unit

Claims (1)

A condenser having a first condenser and a second condenser arranged in series with the first condenser, a flow path switching section for switching a flow path of the refrigerant flowing through the condenser, a first evaporator, a first expander, In addition, a Rankine cycle circuit including a pump and having a first threshold value that is a desired fluid pressure in the downstream-side flow path of the condensing unit,
The condenser is shared by being connected to the upstream inlet and the downstream outlet of the condenser, respectively, and includes a second evaporator, a second expander, and a compressor, and a desired flow path in the downstream flow path of the condenser A refrigeration cycle circuit in which a second threshold value which is a fluid pressure is preset;
Pressure detecting means for detecting fluid pressure downstream of the condensing unit and upstream of the pump and the second evaporator;
A flow path determination unit that determines an optimal flow path in the condensing unit based on a difference between the first threshold value and the second threshold value and a fluid pressure detected by the pressure detection unit;
A refrigeration waste heat recovery system comprising flow path control means for controlling the flow path switching section so that the condensing section has the optimum flow path.

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