Ejector cooling device

Abstract

Provided is an ejector cooling device that can increase the degree of freedom in device layout by reducing the size of a condenser while ensuring a required amount of heat exchange and can also reduce costs. [Solution] An ejector cooling device having a refrigerant pump 3 that pressurizes the refrigerant, a waste heat recovery device 4 that heats the refrigerant with hot water supplied from a heat supply source and generates a driving flow, an expansion valve 5 that depressurizes the refrigerant, an evaporator 6 that cools the water to be cooled with the refrigerant depressurized by the expansion valve 5, an ejector 1 that sucks in the refrigerant evaporated by the evaporator 6 with the driving flow of refrigerant from the waste heat recovery device 4 and discharges a refrigerant mixed with the driving flow and suction flow, and a condenser 2' that cools the refrigerant discharged from the ejector 1, and an internal heat exchanger 7 is provided that exchanges heat between the refrigerant between the discharge side of the ejector 1 and the condenser 2' and the refrigerant between the suction side of the ejector 1 and the evaporator 6, and the refrigerant flowing into the condenser 2' becomes a gas-liquid two-phase refrigerant.

Description

[Technical Field]

[0001] The present invention relates to an ejector cooling device that can increase the degree of freedom in device layout by reducing the size of a condenser while ensuring a required amount of heat exchange, and can also reduce costs. [Background technology]

[0002] An ejector cooling system is a refrigeration cycle device that uses an ejector. It uses hot water, such as waste hot water from a factory, as a heat source to evaporate high-pressure refrigerant pressurized by a refrigerant pump, generating a driving flow for the ejector. The driving flow is sent to the ejector, and the action of the ejector pressurizes the suction flow from the evaporator. The pressurized refrigerant is sent to the condenser, where it is cooled and liquefied by cooling water. The liquefied refrigerant is decompressed to a low-temperature two-phase refrigerant by passing through an expansion valve and sent to the evaporator. The evaporator absorbs heat from the outside as it evaporates, enabling it to generate cold energy, such as chilled water (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-190587 Summary of the Invention [Problem to be solved by the invention]

[0004] The condenser used in the ejector cooling device exchanges heat between the gas-phase refrigerant discharged from the ejector and facility water to cool and liquefy the refrigerant, but when the facility water temperature is high, especially in summer, it is expected that the temperature difference between the refrigerant discharged from the ejector and the facility water used to condense this refrigerant will become small, and in order to ensure the necessary heat exchange capacity even in this case, it is necessary to increase the size of the condenser in advance. However, if the size of the condenser is increased, the volume occupied by the condenser in the entire device increases, reducing the degree of freedom in layout, hindering the compactness of the entire device, and further resulting in problems such as increased costs.

[0005] The present invention has been made in consideration of the above, and aims to provide an ejector cooling device that can reduce the size of the condenser while ensuring the required amount of heat exchange, thereby increasing the flexibility in the layout of the device and reducing costs. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides an ejector cooling device having a refrigerant pump that pressurizes a refrigerant, a heat recovery device that heats the refrigerant with hot water supplied from a heat supply source and generates a driving flow, an expansion valve that depressurizes the refrigerant, an evaporator that cools a medium to be cooled with the refrigerant depressurized by the expansion valve, an ejector that sucks in the refrigerant evaporated by the evaporator with the driving flow of refrigerant from the heat recovery device and discharges a refrigerant that is a mixture of the driving flow and the suction flow, and a condenser that cools the refrigerant discharged from the ejector, wherein an internal heat exchanger is provided that exchanges heat between the refrigerant between the discharge side of the ejector and the condenser and the refrigerant between the suction side of the ejector and the evaporator, and the refrigerant flowing into the condenser is converted into a gas-liquid two-phase refrigerant.

[0007] In the present invention, the condenser has a size that eliminates a heat exchange volume corresponding to the refrigerant in the gas phase region. [Effects of the Invention]

[0008] According to the present invention, it is possible to increase the degree of freedom in the layout of the device by reducing the size of the condenser while ensuring the required amount of heat exchange, and also to reduce costs. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a circuit diagram showing the configuration of a conventional ejector cooling device. [Figure 2] FIG. 2 is a circuit diagram showing the configuration of the ejector cooling device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating the difference in heat exchange amount depending on the phase state of the refrigerant in the condenser. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] <Overall structure> First, a conventional ejector cooling device, which is the premise of the ejector cooling device according to the embodiment of the present invention, will be described. Fig. 1 is a circuit diagram showing the configuration of a conventional ejector cooling device. The ejector cooling device illustrated here recovers waste heat from hot water such as factory wastewater or used cooling water as a heat source, and generates cooling water by cooling a medium to be cooled, for example, the cooled water.

[0012] The ejector cooling device shown in Fig. 1 has an ejector 1, a condenser 2, a refrigerant tank 8, a refrigerant pump 3, and an exhaust heat recovery device 4, which are connected in sequence on a circulation path L1. The ejector cooling device also has a branch path L2. The branch path L2 branches off from a portion upstream of the refrigerant pump 3 at a branch point LS between the condenser 2 and the exhaust heat recovery device 4 on the circulation path L1, and supplies a portion of the refrigerant circulating through the circulation path L1 to the ejector 1 as a suction fluid. Note that the temperature ranges of the refrigerant and water shown in Fig. 1 are merely examples.

[0013] The refrigerant pump 3 circulates and supplies the refrigerant through the circulation path L1. More specifically, the refrigerant pump 3 is, for example, a liquid-phase variable displacement pump, which pressurizes the refrigerant and supplies it to the ejector 1. The exhaust heat recovery device 4 performs heat exchange to heat the refrigerant with supplied hot water, evaporates the refrigerant supplied from the refrigerant pump 3, and supplies it to the ejector 1 as a driving flow.

[0014] The condenser 2 exchanges heat between the refrigerant discharged from the ejector 1 and facility water supplied from the outside, condensing the refrigerant. The facility water supplied from the outside is heated by heat exchange with the refrigerant in the condenser 2, then sent to a cooling device (such as a cooling tower) installed outside the device, cooled by the cooling device, and sent again as facility water to the condenser 2. The refrigerant condensed by the condenser 2 is stored in the subsequent refrigerant tank 8, and the stored refrigerant is then sucked by the refrigerant pump 3 and supplied to the branch path L2 side.

[0015] Branch path L2 is provided with an expansion valve 5 and an evaporator 6. The expansion valve 5 expands and reduces the pressure of the refrigerant that has passed through the condenser 2' and is branched and supplied via branch point LS. The evaporator 6 evaporates the refrigerant by exchanging heat between the liquid-phase refrigerant that has passed through the expansion valve 5 and the cooled water that is supplied to the evaporator 6, thereby generating a suction flow to the ejector 1 and producing cold water that cools the supplied cooled water.

[0016] Fig. 2 is a circuit diagram showing the configuration of an ejector cooling device according to this embodiment. As shown in Fig. 2, this embodiment is provided with an internal heat exchanger 7 that exchanges heat between the refrigerant between the discharge side of the ejector 1 and the condenser 2 and the refrigerant between the suction side of the ejector 1 and the evaporator 6. In this embodiment, the condenser 2 shown in Fig. 1 is replaced with a condenser 2', and the condenser 2' is sized such that the heat exchange volume corresponding to the gas phase region 2a of the condenser 2 is deleted.

[0017] Fig. 3 is a diagram illustrating the difference in heat exchange amount depending on the phase state of the refrigerant in the condensers 2 and 2'. The horizontal axis in Fig. 3 indicates the dimensionless heat exchanger position (normalized position), for example, the distance from the refrigerant outlet side to the refrigerant inlet side, which is the height from the vertical lower end of the condenser 2 as shown in Fig. 2.

[0018] As shown in Figure 3(a), in a conventional condenser 2' including a gas phase region 2a, the refrigerant condenses through phase transitions from the gas phase to a gas-liquid two-phase state and then to a liquid phase from the refrigerant inlet. In the gas phase region 2a and the liquid phase region 2c, the refrigerant temperature drops, but as shown in Figure 3(b), the amount of heat exchange between the refrigerant and facility water is small when the refrigerant is in the gas-liquid two-phase region 2b, and most of the heat exchange in the condenser occurs when the refrigerant is in the gas-liquid two-phase state.

[0019] Therefore, if the gas phase region 2a and the liquid phase region 2c are eliminated, the size of the condenser 2 can be reduced, but the liquid phase region 2c, including the refrigerant tank 8, is a necessary region for avoiding cavitation at the suction port of the refrigerant pump 3 and cannot be eliminated. On the other hand, as shown in Figure 2, the gas phase region 2a can be eliminated by assigning its function to the internal heat exchanger 7. Conventional condensers 2 are enlarged on the assumption that the temperature difference between the refrigerant discharged from the ejector 1 and the facility water used to condense this refrigerant will be small when the facility water temperature is high, especially in summer. However, the size of the condenser 2 can be reduced by eliminating the gas phase region 2a.

[0020] Meanwhile, the gas-phase refrigerant discharged from the ejector 1 undergoes the same heat exchange as in the gas-phase region 2a in the internal heat exchanger 7 and flows into the condenser 2. The refrigerant temperature of the gas-phase refrigerant that has undergone heat exchange in the internal heat exchanger 7 is lowered, and the refrigerant becomes a two-phase gas-liquid state near the refrigerant inlet of the condenser 2'. Specifically, as shown in FIG. 1, the temperature of the refrigerant discharged from the ejector 1 is lowered, for example, from 35 to 55°C to 25 to 40°C, and the refrigerant flows into the condenser 2' in a two-phase gas-liquid state. Here, by using a refrigerant that is lower in temperature and more stable than the facility water that flows from the evaporator 6 into the ejector 1 as the medium that exchanges heat with the gas-phase refrigerant in the internal heat exchanger 7, the heat exchange volume of the internal heat exchanger 7 corresponding to the gas-phase region 2a of the condenser 2 can be reduced.

[0021] As a result, the size of the condenser 2 can be reduced because the heat exchange volume corresponding to the gas phase region 2a can be reduced. Here, since the internal heat exchanger 7 is newly installed, the number of parts in the device increases, but by reducing the size of the condenser 2', the volume occupied by the condenser 2' is reduced, and the degree of freedom in the device layout can be increased. Furthermore, since the cost of a heat exchanger increases as it becomes larger, costs can be reduced by reducing the size of the condenser 2'. Here, although costs increase as the internal heat exchanger 7 is increased, the cost increase of the internal heat exchanger 7 can be smaller than the cost reduction of the condenser 2', which has been made smaller by reducing the gas phase region 2a, resulting in cost reduction. Note that the volume of the gas phase region 2a may be a partial region that is in a gas phase state.

[0022] Note that the configurations illustrated in the above embodiments are merely functional schematics and are not necessarily physically configured as shown. In other words, the distribution and integration of each device and component is not limited to that illustrated, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various usage situations, etc. [Explanation of symbols]

[0023] 1 Ejector 2,2´ Condenser 2a Gas phase region 2b Gas-liquid two-phase region 2c liquid phase region 3 Refrigerant pump 4. Waste heat recovery device 5 Expansion valve 6. Evaporator 7 Internal heat exchanger 8 Refrigerant tank L1 Circulation Route L2 branching pathway LS Junction

Claims

1. An ejector cooling device comprising: a refrigerant pump that pressurizes a refrigerant; a waste heat recovery device that heats the refrigerant with hot water supplied from a heat supply source to generate a driving flow; an expansion valve that decompresses the refrigerant; an evaporator that cools a medium to be cooled with the refrigerant decompressed by the expansion valve; an ejector that draws in the refrigerant evaporated by the evaporator with the driving flow of the refrigerant from the waste heat recovery device and discharges a refrigerant that is a mixture of the driving flow and the suction flow; and a condenser that cools the refrigerant discharged from the ejector, an internal heat exchanger that exchanges heat between a refrigerant between the discharge side of the ejector and the condenser and a refrigerant between the suction side of the ejector and the evaporator, and converts the refrigerant flowing into the condenser into a gas-liquid two-phase refrigerant.

2. 2. The ejector cooling device according to claim 1, wherein the condenser is sized so as to eliminate a heat exchange volume corresponding to the refrigerant in the gas phase region.

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