Flooded evaporators for large suction volume flows

Abstract

The present invention discloses a full-liquid evaporator for large suction volume flow, wherein a gas-liquid separator is arranged inside the cylinder of the horizontal evaporator along the length direction of the cylinder, and the gas-liquid separator is supported by an angle steel baffle between two arc-shaped side walls of the cylinder; the angle steel baffles on each side include a horizontal plate and a vertical plate; the horizontal plate is connected to the arc-shaped side wall of the cylinder, and the vertical plate is spaced apart from the arc-shaped side wall of the cylinder on the side; a first baffle and a second baffle parallel to the horizontal plate are arranged below each angle steel baffle, and the first baffle and the second baffle are spaced apart and respectively fixed to the upper and lower slots on the heat exchange tube support plate on the side. It can prevent suction from carrying liquid, has a compact structure with better uniformity, and effectively prevents heat transfer deterioration and local airflow concentration.

Description

Technical Field

[0001] The invention belongs to the technical field of air conditioning and industrial refrigeration, and in particular relates to a full-liquid evaporator for large suction volume flow. Background Art

[0002] The new environmentally friendly refrigerant R1233zd (E) has zero ODP, extremely low GWP, and better thermodynamic properties, and has the prospect of being applied to high-performance central air conditioners. However, at the same cooling capacity and evaporation temperature, the suction volume flow rate in the evaporator of the R1233zd (E) unit is about 4.5 times that of the commonly used R134a system. The gas flow rate in the evaporator is extremely high, and it is very easy to carry the droplets generated by boiling into the compressor, thereby causing liquid hammer to the compressor, greatly shortening the life of the compressor. Therefore, the conventional practice is to increase the specifications of the cylinder to increase the space and reduce the flow rate, but it will increase the cost. In addition, it is also very important to balance the boiling conditions in the evaporator and avoid the local boiling causing the liquid level to rise and cause the suction to carry liquid. Therefore, it is necessary to reasonably arrange the tube bundles in the evaporator, reserve a gas escape channel, and evenly distribute the refrigerant along the length of the evaporator. Based on this, the present invention designs a full liquid evaporator suitable for the R1233zd (E) unit, which is used to avoid the phenomenon of suction carrying liquid in the evaporator and downgrade the evaporator selection specifications.

[0003] The existing Chinese authorized utility model patent CN208804910U "Multi-stage air-equalizing orifice plate structure and fully liquid evaporator to prevent air suction and liquid carrying" discloses a fully liquid evaporator to prevent air suction and liquid carrying structure, but there are the following problems: for R1233zd refrigerant, 3KPa pressure drop corresponds to 1℃ evaporation temperature, placing an air-equalizing plate (component) in the evaporator will increase the pressure drop in the evaporator and affect the performance of the unit.

[0004] The existing Chinese authorized utility model patent "A new type of high-efficiency fully liquid evaporator (publication number: CN203489538U)" discloses a new type of high-efficiency fully liquid evaporator. The triangular structure distributor adopted in this patent has a relatively high structure height. When the number of heat exchange tubes is the same, it will raise the liquid level in the evaporator and increase the risk of liquid inhalation. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a full liquid evaporator for large suction volume flow, which can prevent suction from carrying liquid, has a compact structure and better uniformity, and effectively prevents heat transfer deterioration and local concentration of airflow.

[0006] The present invention adopts the following technical solutions to solve the above technical problems:

[0007] A full-liquid evaporator for large suction volume flow, characterized in that: a gas-liquid separator is arranged inside the cylinder of the horizontal evaporator along the length direction of the cylinder, and the gas-liquid separator is supported by an angle steel baffle between the two curved side walls of the cylinder; the angle steel baffles on each side include a horizontal plate and a vertical plate; the horizontal plate is connected to the curved side wall of the cylinder, and the vertical plate is spaced apart from the curved side wall of the cylinder on that side; a first baffle and a second baffle parallel to the horizontal support end are arranged under each angle steel baffle, and the first baffle and the second baffle are spaced apart and respectively fixed to the upper and lower grooves on the heat exchange tube support plate on that side.

[0008] In the above technical solution, the angle formed by the horizontal plate and the vertical plate of the angle steel baffle can be 90° or other angles.

[0009] In the above technical solution, the angle steel baffle, the first baffle and the second baffle are all extended along the side wall in the length direction of the cylinder.

[0010] In the above technical solution, the gas-liquid separator is arranged at least below the air intake port of the evaporator cylinder.

[0011] In the above technical solution, a distributor is arranged under the heat exchange tube support plate. The distributor is a three-dimensional cavity with a long axis much larger than the vertical short axis. The top-view projection of the cavity presents a long-axis rhombus extending along the length direction. The thickness or vertical height of the cavity is much smaller than the cavity length. Side openings are arranged circumferentially on the vertical wall of the cavity; a liquid inlet is arranged at the bottom of the distributor.

[0012] In the above technical solution, the transverse cross section or projection of the distributor in the short axis direction is rectangular, rhombus, elliptical or circular.

[0013] In the above technical solution, the side openings of the distributor are rectangular or circular and are evenly distributed on the vertical wall.

[0014] In the above technical solution, the heat exchange tube array forms an air flow channel in the empty tube area on the heat exchange tube support plate.

[0015] In the above technical scheme, the heat exchange tube array reserves parallel gas channels with two ends forked and symmetrically arranged along the center line of the vertical cylinder on the heat exchange tube support plate; or the heat exchange tube array reserves a zigzag, fully empty first V-shaped channel symmetrically arranged along the center line of the vertical cylinder on the heat exchange tube support plate; or the heat exchange tube array reserves a linear second V-shaped channel symmetrically arranged along the center line of the vertical cylinder on the heat exchange tube support plate, and the second V-shaped channel is formed by combining the zigzag, fully empty first V-shaped channel and the inverted triangle pipe layout area spaced apart above to form a linear V-shaped gas channel.

[0016] Compared with the prior art, the present invention designs a staggered multi-stage structure arranged inside the evaporator cylinder, which can absorb a large amount of air without liquid, and has the following beneficial effects:

[0017] The anti-inhalation liquid structure formed by the separator + baffle combination, the reasonable layout of the separator position and thickness, and the downgraded evaporator selection specifications can avoid the risk of inhalation liquid;

[0018] A distributor with compact structure and better flow distribution uniformity is designed, which can make the boiling uniformity in the container better and prevent the local liquid level from rising too high and causing liquid to be carried by air;

[0019] Reasonable arrangement of heat exchange tubes leaves gas escape channels to prevent heat transfer deterioration and local concentration of airflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is an overall structural diagram of a flooded evaporator for large suction volume flow according to the present invention.

[0021] Figure 2 for Figure 1 Split diagram of .

[0022] Figure 3 This is a partial enlarged view of the cross section of a flooded evaporator.

[0023] Figure 4 This is the structure diagram of the distributor.

[0024] Figure 5a , 5b 5 and 5c are three structural diagrams of the maximum cross-section of the zy surface projection of the distributor.

[0025] Figure 6 It is an implementation structure of the distributor side opening.

[0026] Figure 7 Another implementation structure of the distributor side opening.

[0027] Figure 8 An implementation arrangement structure of air flow channels reserved for arraying heat exchange tubes on a support plate.

[0028] Fig. 9 A second implementation arrangement structure of the air flow channels reserved for arranging heat exchange tubes on a support plate.

[0029] Fig.10 A third implementation arrangement structure of the air flow channels reserved for arranging heat exchange tubes on a support plate.

[0030] The corresponding reference numerals in the accompanying drawings are as follows: 1: Cover B, 2: Cover A, 3: Intake pipe, 4: Gas-liquid separator, 5: Liquid inlet, 6: Distributor, 7: Support plate, 81: Angle steel baffle, 82: First baffle, 83: Second baffle, 61: Rectangular cross section, 62: Elliptical cross section, 63: Circular cross section, 64: Circular side hole, 65: Square side hole, 71: Gas channel, 72: First V-shaped channel, 73: Second V-shaped channel. DETAILED DESCRIPTION

[0031] The full liquid evaporator for large suction volume flow implemented according to the present invention has a structure as follows Figure 1-9 shown.

[0032] Figure 1-2 It is a horizontal full-liquid evaporator, with both ends closed by cover B 1 and cover A 2, and an intake pipe 3 is connected to the evaporator shell; inside the evaporator shell, a gas-liquid separator 4, a support plate 7 for supporting the heat exchange tube, and a distributor 6 for distributing the refrigerant along the length direction of the evaporator cylinder are supported from top to bottom between cover B 1 and cover A 2, and a liquid inlet 5 is connected below the distributor 6.

[0033] like Figure 3 The structure for preventing air from being sucked and liquid is mainly composed of a gas-liquid separator 4, an angle steel baffle 81, a first baffle 82 and a second baffle 83. The cross section of the angle steel baffle 81 is preferably L-shaped, and the gas-liquid separator 4 is supported and arranged between the two sides of the evaporator cylinder by the angle steel baffle 81 arranged along the length direction, and a gap is reserved between the vertical plate of the angle steel baffle 81 and the inner wall of the evaporator cylinder, and the radial horizontal plate of the angle steel baffle 81 is fixedly arranged on the inner wall of the evaporator cylinder, so that the two side ends of the gas-liquid separator 4 are supported on the radial horizontal plate without contacting the inner walls of the two sides of the evaporator cylinder. A first baffle 82 and a second baffle 83 parallel to the radial horizontal plate of the angle steel baffle 81 are respectively arranged on the inner wall of the evaporator cylinder below the angle steel baffle 81, and the first baffle 82 and the second baffle 83 are arranged at intervals up and down; two slots are correspondingly arranged on the non-heat exchange tube arrangement areas on both sides of the support plate 7 that cooperate with the inner wall of the cylinder, and the support plate 7 is respectively clamped on the first baffle 82 and the second baffle 83 through the upper and lower slots, so that the support plate 7 is supported between the inner walls on both sides of the evaporator cylinder.

[0034] The specific principle of preventing liquid carryover is as follows: the gaseous refrigerant carrying boiling splashing droplets passes through the gas-liquid separator 4, and the gas can pass through the gas-liquid separator 4 (grid type or conventional fin type) and enter the compressor through the suction pipe 3, while the large-diameter droplets hit the gas-liquid separator 4 filler and are captured. Finally, the liquid refrigerant accumulates more and more in the gas-liquid separator 4 and drips onto the heat exchange tubes of the support plate 7 by gravity to continue heat exchange and evaporation. Since there are gaps between the heat exchange tube bundle and the cylinder, the liquid can easily flow upward along the cylinder wall through these gaps, eventually causing the suction to carry liquid, so the side wall is arranged with the above-mentioned three-baffle structure, the first baffle, the second baffle and the angle steel baffle, such as Figure 3 The angle steel baffle can not only block the liquid, but also fix and position the separator.

[0035] It should be noted that the gas-liquid separator 4 can be spread over the entire length of the evaporator cylinder, and can also be shortened as the load of the unit decreases, but it must be ensured that there is a separator directly below the suction pipe 3. The installation position of the separator also has a great influence on the gas-liquid separation effect. Since the process of the airflow carrying the droplets upward is an accelerated process, placing the separator in a low-speed area is not conducive to the impact separation of the droplets. When placed in a high-speed area, it is easy to take the separated droplets away again to form secondary entrainment. The optimal installation position of the gas-liquid separator 4 should be on a plane 50-150mm above the liquid level (depending on the load of the unit). In addition, the thickness of the gas-liquid separator 4 is crucial. If the separator is too thin, the gas-liquid separation effect is poor. If the separator is too thick, the pressure drop in the evaporator will increase and the performance of the unit will be reduced. The preferred thickness range of the gas-liquid separator 4 is 25-150mm.

[0036] In order to achieve uniform distribution of the refrigerant along the length of the evaporator and ensure relatively uniform boiling in the container, a side opening distributor 6 with a gradually shrinking flow area is designed. The distributor 6 is a three-dimensional cavity with a long axis much larger than the vertical short axis. The projection of the cavity in the top view is a long axis diamond extending along the length direction. The thickness or vertical height of the cavity is much smaller than the length of the cavity. Side openings are arranged on the vertical wall of the cavity along the circumference; a liquid inlet 5 is arranged at the bottom center of the distributor 6. Figure 4-7 As shown, since the liquid inlet 5 is located at the bottom of the distributor 6, the flow rate in the distributor gradually decreases from the liquid inlet 5 to both sides. The flow channel with a gradually decreasing flow area is designed to achieve uniform pressure in the distributor, which is beneficial to the distributor along the length direction ( Figure 4 In the X direction, Figure 1 The distribution uniformity of the cylinder length direction. Figure 4 and 5a -5c, the maximum cross-sectional projection of the distributor 6 on the zy surface can be Figure 5a The rectangle 61 can also be Figure 5b oval 62, Figure 5c The vertical wall of the cavity of the distributor 6 adopts a side opening ( Figure 6 Embodiments of circular side openings 64 or Figure 7 The rectangular side openings 65) in the embodiment are arranged to further adjust the uniformity of the distribution of the refrigerant in the length direction of the cylinder by adjusting the density of the side openings. Compared with the upper openings, the side openings can effectively reduce the height of the distributor, thereby reducing the height of the container pipe layout, leaving enough space for gas-liquid separation.

[0037] Since the gas evaporated from the heat exchange tube has a large volume flow rate and high flow rate, in order to prevent the boiling liquid level from being raised and the local airflow concentration from causing serious splashing of droplets, it is necessary to reasonably arrange the heat exchange tubes on the support plate 7, evenly distribute the gas in the pool boiling, and reserve a gas channel. In addition, the effective and rapid escape of the airflow can also prevent excessive gas in the pool boiling from adhering to the surface of the heat exchange tube and being unable to escape, causing deterioration of heat transfer. Figure 8-10 As shown, there are three typical implementation arrangements of the air flow channels. Figure 8 In the heat exchange tube array, a gas channel 71 with two ends bifurcated and parallel to each other and symmetrically along the center line of the vertical cylinder is reserved on the support plate 7; Fig. 9 The middle heat exchange tube array reserves a sawtooth-shaped full-air first V-shaped channel 72 on the support plate 7, which is symmetrical along the center line of the vertical cylinder; Fig.10 In the heat exchange tube array, a linear second V-shaped channel 73 symmetrical along the vertical center line of the cylinder is reserved on the support plate 7. The second V-shaped channel 73 is formed into a linear V shape by a serrated full-air first V-shaped channel 72 and an inverted triangular pipe arrangement spaced apart above.

[0038] The refrigerant enters the distributor 6 from the bottom of the horizontal full-liquid evaporator through the liquid inlet 5. The distributor 6 can realize uniform distribution of the refrigerant along the length direction, which is beneficial to relatively uniform boiling in the container. After entering the evaporator, the refrigerant exchanges heat with the heat exchange tube, boils and evaporates into gaseous refrigerant, and the gaseous refrigerant carries the boiling splashed liquid droplets and moves rapidly toward the air intake port 3 through the air flow channel, and realizes gas-liquid separation through the gas-liquid separator 4, finally ensuring that the gaseous refrigerant does not carry liquid droplets and safely enters the compressor from the air intake port 3.

Claims

1. A flooded evaporator for large suction volume flow, characterized in that: A gas-liquid separator is arranged inside the cylinder of the horizontal evaporator along the length direction of the cylinder, and the gas-liquid separator is supported by an angle steel baffle between the two arc-shaped side walls of the cylinder; the angle steel baffles on each side include a horizontal plate and a vertical plate; the horizontal plate is connected to the arc-shaped side wall of the cylinder, and the vertical plate is spaced apart from the arc-shaped side wall of the cylinder on the side where it is located; a first baffle and a second baffle parallel to the horizontal plate are arranged below each angle steel baffle, the first baffle and the second baffle are spaced apart on both sides, and heat exchange tube support plates are respectively arranged on each side, and upper and lower grooves are arranged on each heat exchange tube support plate, and the first baffle and the second baffle are respectively fixed to the upper and lower grooves on the heat exchange tube support plates on both sides; a distributor is arranged below the heat exchange tube support plate; the distributor is a three-dimensional cavity with a long axis much larger than a vertical short axis, and the top view projection of the cavity presents a long axis rhombus extending in the length direction, the thickness or vertical height of the cavity is much smaller than the length of the cavity, and side openings are arranged circumferentially on the vertical wall of the cavity; A liquid inlet is arranged at the bottom of the distributor.

2. The flooded evaporator for large suction volume flow according to claim 1, characterized in that: The cross section of the angle steel baffle is L-shaped, and the first baffle and the second baffle are both extended along the side wall in the length direction of the cylinder.

3. The flooded evaporator for large suction volume flow according to claim 1, characterized in that: The gas-liquid separator is arranged at least below the air intake port of the evaporator cylinder.

4. The flooded evaporator for large suction volume flow according to claim 1, characterized in that: The transverse cross section or projection of the distributor in the short axis direction is rectangular, rhombus, elliptical or circular.

5. The flooded evaporator for large suction volume flow according to claim 1, characterized in that: The side openings of the distributor are rectangular or circular and are evenly distributed on the vertical wall.

6. The flooded evaporator for large suction volume flow according to claim 1, characterized in that: The heat exchange tube array forms an air flow channel in the empty tube area on the heat exchange tube support plate.

7. The flooded evaporator for large suction volume flow according to claim 6, characterized in that: The heat exchange tube array reserves parallel gas channels with two ends forked and symmetrically arranged along the center line of the vertical cylinder on the heat exchange tube support plate; or the heat exchange tube array reserves a symmetrical zigzag full-empty first V-shaped channel on the heat exchange tube support plate along the center line of the vertical cylinder; or the heat exchange tube array reserves a linear second V-shaped channel on the heat exchange tube support plate along the center line of the vertical cylinder, and the second V-shaped channel is formed by combining the zigzag full-empty first V-shaped channel and the inverted triangle pipe layout area spaced apart above to form a linear V-shaped gas channel.

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