Chiller and air conditioning system

Abstract

A chiller (200, 300) comprises compressors (4), a condenser (2), a first throttling element (71), and an evaporator (1), wherein the compressors comprise a first EVI compressor (41) and a second EVI compressor (42), which are connected in parallel. The chiller further comprises a second throttling element (72), a third throttling element, an economizer (3), a first manifold (81) and a second manifold (82), wherein the economizer comprises a first heat-exchange passage (61), a second heat-exchange passage (62) and a third heat-exchange passage (63), the second heat-exchange passage, the first heat-exchange passage is connected between the condenser and the first throttling element, the first manifold is sequentially connected to the second throttling element, the second heat-exchange passage and the first supplement port (411), and the second manifold is sequentially connected to the third throttling element, the third heat-exchange passage and the second supplement port (421). The chiller solves the problem of backflow of refrigerant between supplement ports and has a lower cost.

Description

Technical Field

[0001] The disclosure relates to the technical field of air conditioning, in particular, to a chiller and an air conditioning system.Background Art

[0002] At present, the enhanced vapor injection (EVI) technology has been widely used to solve the problem of a drastic decrease in heat supply in the low-temperature environment in winter. To increase the heat supply, multiple EVI compressors are used in parallel in some large and medium-sized chillers.

[0003] To allow for synchronous use of multiple EVI compressors in case of a large heat supply demand and use of only part of the EVI compressors in case of a low heat supply demand and to prevent an intermediate-pressure refrigerant from flowing from supplement ports of EVI compressors in an on state back to supplement ports of EVI compressors in an off state when only part of the EVI compressors is used, an electromagnetic valve is arranged on a branch between an economizer and the supplement port of each EVI compressor. The arrangement of multiple electromagnetic valves leads to a higher cost.Summary

[0004] The technical issue to be settled by the disclosure is to solve the problem of backflow of a refrigerant between supplement ports and reduce the cost for a chiller using multiple EVI compressors connected in parallel.

[0005] According to a first aspect of the invention there is provided a chiller, comprising compressors, a condenser, a first throttling element and an evaporator, wherein the compressors comprise a first EVI compressor and a second EVI compressor which are connected in parallel, the first EVI compressor is provided with a first supplement port, and the second EVI compressor is provided with a second supplement port; the chiller further comprises a second throttling element, a third throttling element, an economizer, a first manifold and a second manifold, wherein the economizer comprises a first heat-exchange passage, a second heat-exchange passage and a third heat-exchange passage, the second heat-exchange passage and the third heat-exchange passage being configured to exchange heat with the first heat-exchange passage, and the first heat-exchange passage being connected between the condenser and the first throttling element; the first manifold is connected between the first throttling element and the condenser and sequentially connected to the second throttling element, the second heat-exchange passage and the first supplement port; and the second manifold is connected between the first throttling element and the condenser and sequentially connected to the third throttling element, the third heat-exchange passage and the second supplement port.

[0006] Optionally, the first manifold and the second manifold are connected between the first throttling element and the first heat-exchange passage.

[0007] Alternatively, the first manifold and the second manifold may be connected between the condenser and the first heat-exchange passage.

[0008] Optionally, the first manifold is connected between the condenser and the first heat-exchange passage, and the second manifold is connected between the first throttling element and the first heat-exchange passage.

[0009] Optionally, no electromagnetic valve is arranged between the first supplement port and the second heat-exchange passage, and no electromagnetic valve is arranged between the second supplement port and the third heat-exchange passage.

[0010] Optionally, the economizer is a plate heat exchanger.

[0011] Optionally, one of the first EVI compressor and the second EVI compressor is started individually, or the first EVI compressor and the second EVI compressor are started synchronously.

[0012] It will be appreciated that some or all of the above optional features may be freely combined in embodiments of the invention unless explicitly stated otherwise.

[0013] According to a second aspect of the invention there is provided an air conditioning system, comprising a chiller according to the first aspect of the invention.

[0014] Under the precondition of avoiding backflow of a refrigerant between supplement ports, the chiller provided by the invention reduces an extra cost caused by the use of electromagnetic valves, avoids the throttling effect of the electromagnetic valves, and improves the control accuracy, as compared with a chiller using two electromagnetic valves and two expansion valves (including an expansion valve used as a main throttling element in a main passage) in the prior art.Descriptions of the Drawings

[0015] FIG. 1 is a schematic diagram of a chiller in the prior art. FIG. 2 is a system diagram of a chiller. FIG. 3 is a system diagram of a chiller. List of Reference Numerals:

[0016] 100, 200, 300, chiller; 1, evaporator; 2, condenser; 3, economizer; 31, economizer main passage inlet; 32, economizer main passage outlet; 4, EVI compressor; 40, supplement port; 41, first EVI compressor; 411, first supplement port; 42, second EVI compressor; 421, second supplement port; 43, compressor exhaust port; 44, compressor suction port; 51, first electromagnetic valve; 52, second electromagnetic valve; 61, first heat-exchange passage; 62, second heat-exchange passage; 63, third heat-exchange passage; 71, first throttling element; 72, second throttling element; 73, third throttling element; 74, manifold; 81, first manifold; 82, second manifold.Detailed Description

[0017] Embodiments of the invention are described below in conjunction with the accompanying drawings. It will be understood that the embodiments in the following description are merely illustrative ones and that other embodiments which are not described in detail may fall within the scope of the appended claims. It will further be understood that the scope of protection is defined by the appended claims.<Prior art>

[0018] First, a more detailed description of the prior art is given below with reference to the accompanying drawing. FIG. 1 illustrates a chiller 200 provided with multiple EVI compressors 4 connected in parallel in the prior art.

[0019] Referring to FIG. 1, a supplement port 40 of each EVI compressor 4 in the chiller 100 in the prior art is connected to an electromagnetic valve (a first electromagnetic valve 51 or a second electromagnetic valve 52). Specifically, the chiller 100 comprises a first EVI compressor 41, a second EVI compressor 42, a condenser 2, an economizer 3, a first throttling element 71 and an evaporator 1, and supplement ports 40 of the first EVI compressor 41 and the second EVI compressor 42 are respectively connected to the first electromagnetic valve 51 and the second electromagnetic valve 52.

[0020] The economizer 3 comprises a first heat-exchange passage 61 and a second heat-exchange passage 62, the first throttling element 71 is arranged in a line between the evaporator 1 and the first heat-exchange passage 61, a manifold 74 is connected between the first heat-exchange passage 61 and the first throttling element 71, the manifold 74 is connected to the second heat-exchange passage 62, a second throttling element 72 is arranged in the manifold 74, and the first throttling element 71 and the second throttling element 72 are expansion valves.

[0021] In a case where multiple EVI compressors 4 operate synchronously, the quantity of a refrigerant in two branches is controlled by the first electromagnetic valve 51 and the second electromagnetic valve 52 respectively. When one EVI compressor 4 is stopped, the first electromagnetic valve 51 or the second electromagnetic valve 52 corresponding to the EVI compressor 4 can be turned off to prevent mixing or backflow of the intermediate-pressure refrigerant between the supplement ports 40. However, due to the use of too many electromagnetic valves (the first electromagnetic valve 51 and the second electromagnetic valve 52), the cost is increased. In addition, the electromagnetic valves have a throttling effect, a low control accuracy and other problems.<First Embodiment>

[0022] This embodiment provides a chiller 200. As shown in FIG. 2, the chiller 200 comprises two EVI compressors 4 (a first EVI compressor 41 and a second EVI compressor 42), which are connected in parallel, a condenser 2, an economizer 3, a first throttling element 71 and an evaporator 1. In this embodiment, the number of EVI compressors 4 connected in parallel is two. In other embodiments, the number of EVI compressors 4 connected in parallel may be three or more. The number of EVI compressors 4 is not limited.

[0023] Each EVI compressor 4 is provided with a compressor exhaust port 43 and a compressor suction port 44, wherein the compressor exhaust port 43 is connected to the condenser 2, and the compressor suction port 44 is connected to the evaporator 1. In some embodiments, the compressor exhaust ports 43 of the EVI compressors 4 are connected and then connected to the condenser 2, or the compressor exhaust ports 43 of the EVI compressors 4 are connected to the condenser 2 by means of a refrigerant mixing and distribution pipe system. The connection between the EVI compressors 4, the evaporator 1 and the condenser 2 is not shown in the drawings below.

[0024] The economizer 3 is arranged between the condenser 2 and the first throttling element 71. The economizer 3 is provided with a first heat-exchange passage 61, a second heat-exchange passage 62 and a third heat-exchange passage 63, wherein the first heat-exchange passage 61 is connected to a main passage of a refrigerant flow circuit, that is, the first heat-exchange passage 61 is connected between the condenser 2 and the first throttling element 71. Two ends of the first heat-exchange passage 61 correspond to an economizer main passage inlet 31 and an economizer main passage outlet 32, respectively. Referring to FIG. 2, the economizer main passage inlet 31 is connected to a refrigerant outlet of the condenser 2, and the economizer main passage outlet 32 is connected to a refrigerant inlet of the evaporator 1 by means of the first throttling element71.

[0025] The second heat-exchange passage 62 and the third heat-exchange passage 63 are coupled to the first heat-exchange passage 61, and a refrigerant, the temperature of which is deceased by throttling expansion of a second throttling element 72, in the second heat-exchange passage 62 and / or a refrigerant, the temperature of which is decreased by throttling expansion of a third throttling element 73, in the third heat-exchange passage 63 exchanges heat with a refrigerant with a relatively high temperature in the first heat-exchange passage 61.

[0026] In this embodiment, the chiller 200 comprises two manifolds (a first manifold 81 and a second manifold 82) connected to an outlet side of the first heat-exchange passage 61 of the economizer 3. Wherein, the first manifold 81 is sequentially connected to the second throttling element 72, the second heat-exchange passage 62 and a first supplement port 411, and the second manifold 82 is sequentially connected to the third throttling element 73, the third heat-exchange passage 63 and a second supplement port 421. Because two independent branches are used to supplement gas to the first EVI compressor 41 and the second EVI compressor 42 respectively, the first manifold 81 and the second manifold 82 branch from the inlet side or an outlet side of the first heat-exchange passage 61, and the second throttling element 71 (or the third throttling element 73) and the economizer 3 are arranged between the branch point (a joint between the first manifold 81 or second manifold 82 and the main passage) and the corresponding supplement port, such that when one EVI compressor 4 is stopped, the second throttling element 72 or the third throttling element 73 corresponding to the EVI compressor 4 can be turned off to prevent mixing of the intermediate-pressure refrigerant between multiple supplement ports.

[0027] In this embodiment, the first throttling element 71, the second throttling element 72 and the third throttling element 73 are all expansion valves. Compared with the chiller using two electromagnetic valves and two expansion valves (including an expansion valve used as a main throttling element in a main passage) in the prior art shown in FIG. 1, the chiller 200 provided by this embodiment can reduce an extra cost caused by the use of electromagnetic valves, can effectively avoid the throttling effect, and can separately and accurately control the corresponding EVI compressor 4 by means of the second throttling element 72 or the third throttling element 73 to improve the control accuracy.

[0028] The capacity of the first EVI compressor 41 may be the same as or different from the capacity of the second EVI compressor 42. In this embodiment, an opening of the first throttling element 72 and an opening of the third throttling element 73 can be separately and accurately controlled to ensure that the refrigerant entering the supplement ports of the compressors is intermediate-temperature and intermediate-pressure steam and has a suitable flow rate and velocity. By controlling the openings of the throttling elements connected to the supplement ports of the compressors, particularly by separately controlling the compressors according to different conditions of the compressors, the control accuracy and system stability can be improved, thus effectively satisfying the control requirements of multiple EVI compressors 4 under different condition.

[0029] Referring to FIG. 2, when a system operates, the refrigerant flowing out of the outlet of the condenser 2 is divided by means of the first manifold 81 and the second manifold 82 before flowing into an inlet end of the first throttling element 71. After being divided, the refrigerant is expanded respectively by the second throttling element 72 and the third throttling element 73 to release heat, and the cooled refrigerant can cool the refrigerant in the first heat-exchange passage 61 of the main passage, such that the refrigerant in the first heat-exchange passage 61 can be cooled to an appropriate temperature before entering the first throttling element 71. The temperature of the refrigerant entering the supplement ports can be accurately controlled.

[0030] In this embodiment, after the refrigerant flows through the condenser 2, part of the refrigerant flows through the first heat-exchange passage 61 in the economizer 3, is then expanded by the first throttling element 71 to release heat, then absorbs heat in the evaporator 1, then returns into the EVI compressors 4, and finally enters the two compressors via the compressor suction ports to be compressed preliminarily. The other part of the refrigerant is divided in front of the first throttling element 71 into two paths, which respectively enter the first manifold 81 and the second manifold 82; the two paths of refrigerant are expanded respectively by the second throttling element 72 and the third throttling element 73 to release heat, then respectively pass through the second heat-exchange passage 62 and the third heat-exchange passage 63 to exchange heat with the refrigerant in the first heat-exchange passage 61, then enter the first supplement port 411 of the first EVI compressor 41 and the second supplement port 421 of the second EVI compressor 42 respectively, and are compressed again after being mixed with the intermediate-temperature and intermediate-pressure refrigerant that is compressed preliminarily and enters the compressors via the compressor suction ports 44, such that a high-temperature and high-pressure refrigerant is obtained and finally flows out via the exhaust outlets 43 of the compressors.

[0031] In this embodiment, the refrigerant is divided into two paths, which are expanded to release heat and then respectively enter the second heat-exchange passage 62 and the third heat-exchange passage 63, and the flow direction of the refrigerant in the second heat-exchange passage 62 and the third heat-exchange passage 63 is opposite to the flow direction of the refrigerant in the first heat-exchange passage 61, such that the heat-exchange effect is improved. In some embodiments, the flow direction of the refrigerant in the second heat-exchange passage 62 and the third heat-exchange passage 63 may be the same as the flow direction of the refrigerant in the first heat-exchange passage 61. The disclosure has no limitations in this aspect.<Embodiment 2>

[0032] This embodiment provides a chiller 300 provided with a first manifold 81 and a second manifold 82, which are connected between the condenser 2 and the heat-exchange passage 61.

[0033] The structure of the economizer 3 is the same as the structure of the economizer 3 in the first embodiment and will not be repeated here. Referring to FIG. 3, the refrigerant flowing out of condenser 2 is divided at the branch point, wherein one part of the refrigerant directly flows to the first heat-exchange passage 61 via the economizer main passage inlet 31 of the economizer 3; the other part of the refrigerant is divided into two paths, which respectively enter the first manifold 81 and the second manifold 82, are expanded respectively by the second throttling element 72 and the third throttling element 73 to release heat, and then respectively flow into the second heat-exchange passage 62 and the third heat-exchange passage 63 to further cool the refrigerant in the first heat-exchange passage 61, then flow out of the economizer 3, and finally flow to the first supplement port 411 and the second supplement port 422 of the EVI compressors 4 respectively.

[0034] In this embodiment, the flow direction of the refrigerant in the second heat-exchange passage 62 and the third heat-exchange passage 63 is the same as the flow direction of the refrigerant in the first heat-exchange passage 61. In some embodiment, the flow direction of the refrigerant in the second heat-exchange passage 62 and the third heat-exchange passage 63 may be opposite to the flow direction of the refrigerant in the first heat-exchange passage 61.

[0035] In this scheme, the branch point is arranged on the inlet side of the economizer (between the economizer main passage inlet 31 and the condenser 2). The refrigerant flowing out of the outlet of the condenser 2 is directly divided at the branch point rather than flowing into the first heat-exchange passage 61; the refrigerant is then expanded to release heat and then cools the refrigerant in the first heat-exchange passage 61; and finally, the refrigerant flows to the supplement ports of the compressors. By dividing the refrigerant before heat exchange, a temperature difference between heat-exchange lines can be increased, thus improving the cooling efficiency of the refrigerant in the first heat-exchange passage 61.

[0036] The branch point is located in front of economizer 3 in the first embodiment and is located behind economizer 3 in the second embodiment. In other embodiments, one branch point may be arranged in front of the economizer 3, and the other branch point may be arranged behind the economizer 3, that is, the first manifold 81 may be connected between the condenser 2 and the first heat-exchange passage 61, and the second manifold 82 may be connected between the first throttling element 71 and the first heat-exchange passage 61.

[0037] In this embodiment, the economizer 3 may be a plate heat exchanger.

[0038] In the above embodiments, one of the first EVI compressor 41 and the second EVI compressor 42 is started individually, or the first EVI compressor 41 and the second EVI compressor 42 are started synchronously. Referring to FIGS. 2 and 3, in the embodiments of the invention, the branch points are located on a side, away from the supplement ports, of the economizer, so when one of the first EVI compressor 41 and the second EVI compressor 42 is started individually or the first EVI compressor 41 and the second EVI compressor 42 are both started, mixing or backflow of the refrigerant can be prevented by turning off the second throttling element 72 or the third throttling element 73.

[0039] In this way, the temperature and flow rate of the intermediate-pressure refrigerant flowing into the first supplement port 411 and the second supplement port 421 can be separately and accurately controlled; when only part of the EVI compressors 4 operate, backflow or mixing of the intermediate-pressure refrigerant between the supplement ports will not occur. Under the precondition of avoiding backflow or mixing of the intermediate-pressure refrigerant between the supplement ports, the chillers 200 and 300 in the above embodiments use fewer electromagnetic valves, thus reducing the cost and avoiding the throttling effect and low control accuracy caused by the electromagnetic valves.

[0040] The above embodiments are merely illustrative, and are not used to limit the invention. The skilled person will understand that various modifications may be made to the described embodiments without departing from the scope of the invention, which is defined by the appended claims.

Claims

1. A chiller (200, 300), comprising compressors (4), a condenser (2), a first throttling element (71) and an evaporator (1), the compressors comprising a first EVI compressor (41) and a second EVI compressor (42) which are connected in parallel, the first EVI compressor (41) being provided with a first supplement port (411), and the second EVI compressor (42) being provided with a second supplement port (421), wherein the chiller further comprises: a second throttling element (72); a third throttling element (73); an economizer (3), comprising a first heat-exchange passage (61), a second heat-exchange passage (62) and a third heat-exchange passage (63), the second heat-exchange passage (62) and the third heat-exchange passage (63) configured to exchange heat with the first heat-exchange passage (61), and the first heat-exchange passage (61) being connected between the condenser (2) and the first throttling element (71); a first manifold (81), connected between the first throttling element (71) and the condenser (2) and sequentially connected to the second throttling element (72), the second heat-exchange passage (62) and the first supplement port (411); and a second manifold (82), connected between the first throttling element (71) and the condenser (2) and sequentially connected to the third throttling element (73), the third heat-exchange passage (63) and the second supplement port (421).

2. The chiller (200) according to Claim 1, wherein the first manifold (81) and the second manifold (82) are connected between the first throttling element (71) and the first heat-exchange passage (61).

3. The chiller (300) according to Claim 1, wherein the first manifold (81) and the second manifold (82) are connected between the condenser (2) and the first heat-exchange passage (61).

4. The chiller (200, 300) according to any preceding claim, wherein no electromagnetic valve is arranged between the first supplement port (411) and the second heat-exchange passage (62), and no electromagnetic valve is arranged between the second supplement port (421) and the third heat-exchange passage (63).

5. The chiller (200, 300) according to any preceding claim, wherein the economizer (3) is a plate heat exchanger.

6. The chiller (200, 300) according to any preceding claim, wherein one of the first EVI compressor (41) and the second EVI compressor (42) are started individually, or the first EVI compressor (41) and the second EVI compressor (42) are started synchronously.

7. An air conditioning system, comprising the chiller (200, 300) according to any one of Claims 1-6.

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