A low-prandtl number dispenser

Abstract

The application relates to a low-Prandtl-number distributor which comprises a bottom plate, an inner baffle, a guide plate, an accelerating plate, a decelerating plate and end plates, the two end plates are arranged on the left and right, the bottom plate, the inner baffle, the guide plate, the accelerating plate and the decelerating plate are sequentially arranged from bottom to top between the two end plates, a plurality of accelerating plate holes are uniformly distributed on the accelerating plate, a plurality of decelerating plate holes are uniformly distributed on the decelerating plate, the inner baffle, the guide plate and the two end plates form a guide cavity, the guide plate, the accelerating plate and the two end plates form an accelerating cavity, the guide cavity and the accelerating cavity are communicated, the accelerating plate, the decelerating plate and one end plate form a decelerating cavity. The application creates a low-Prandtl-number gas-liquid two-phase mixture by changing the refrigerant flow velocity and macro flow state, and has the advantages of uniformly distributing the refrigerant, improving the utilization rate of heat exchange area, improving the heat transfer performance, uniformly and stably discharging the refrigerant and reducing the refrigerant erosion and wear of the heat exchange tube bundle.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a low Prandtl number distributor. Background Art

[0002] In the evaporator of refrigeration and air conditioning equipment, if there is no distributor, the distributor design concept is incorrect, or the distributor structure is unreasonable, the refrigerant will be unevenly distributed when entering the heat exchange tubes. The refrigerant is unevenly distributed outside the heat exchange tube bundle and cannot fully wet or immerse the tube bundle. The heat exchange area cannot be fully utilized, resulting in poor heat transfer efficiency, reduced evaporation temperature, and unsatisfactory refrigerant evaporation effect. The gas phase of the refrigerant entering the evaporator is largely separated from the liquid phase, resulting in insufficient convective heat transfer, large refrigerant charge volume, high refrigerant loss, and high product material cost. The local refrigerant flow rate is too high, causing erosion of the heat exchange tube bundle, which can easily cause liquid carryover at the evaporator outlet and cause local high concentration accumulation of lubricating oil entering the evaporator. Over time, it affects the service life of the heat exchange product and the safe operation of the entire unit. Therefore, solving the refrigerant distribution problem is a crucial factor in the design process of tubular heat exchangers. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned shortcomings by creating a two-phase mixture with an intermittent flow or annular flow pattern, changing the Prandtl number of a pure liquid to a Prandtl number close to that of a gas phase mixture. A low Prandtl number distributor is provided for distributing refrigerant in a shell-and-tube heat exchanger with evaporation outside the tube bundle. Its special internal structure has the advantages of uniformly distributing the refrigerant, improving the utilization rate of the heat exchange area, and rationally managing the accumulation area of ​​high-concentration oil, thereby achieving the advantages of flow enhancement, improving heat transfer performance, significantly reducing the refrigerant charge volume, and reducing the erosion and wear of the heat exchange tube bundle by the refrigerant.

[0004] The object of the present invention is achieved like this:

[0005] A low Prandtl number distributor is installed at the bottom of an evaporator and includes a bottom plate, an inner partition, a guide plate, an acceleration plate, a deceleration plate and an end plate. Between the two end plates arranged on the left and right, the bottom plate, the inner partition, the guide plate, the acceleration plate and the deceleration plate are arranged in sequence from bottom to top. A plurality of acceleration plate holes are evenly distributed on the acceleration plate, and a plurality of deceleration plate holes are evenly distributed on the deceleration plate. The inner partition, the guide plate and the two end plates form a guide cavity, the guide plate, the acceleration plate and the two end plates form an acceleration cavity, the guide cavity and the acceleration cavity are connected, and the acceleration plate, the deceleration plate and one end plate form a deceleration cavity.

[0006] Preferably, one end of the guide plate is welded to the end plate on the corresponding side, and a fluid turning gap is left between the other end and the end plate on the corresponding side, so that the acceleration chamber and the guide chamber arranged above and below are connected, and the fluid in the guide chamber turns and flows to the acceleration chamber.

[0007] Preferably, the guide cavity and the acceleration cavity are distributed at unequal intervals, and the cavity spacing between the two decreases from bottom to top.

[0008] Preferably, the inner partition, guide plate, acceleration plate and deceleration plate are all ∧-shaped and formed by integral bending, with the bending angles being consistent.

[0009] Preferably, the bending angles of the inner partition, guide plate, acceleration plate and deceleration plate are 45°, 60°, 90° or 120°.

[0010] Preferably, the accelerator plate hole and the decelerator plate hole are staggered.

[0011] Preferably, the bottom plate, inner partition and left and right guide partitions constitute a feed cavity, the two guide partitions are arranged on the inner sides of the two end plates, the bottom of the feed cavity formed by the bottom plate is provided with a bottom plate hole, and the top of the feed cavity formed by the inner partition is provided with an inner partition with a hole section.

[0012] Preferably, pads are provided between the inner partition and the guide plate, between the guide plate and the accelerator plate, and between the accelerator plate and the decelerator plate, so as to support adjacent plates through the pads.

[0013] Preferably, the bottom plate is in an arc shape coaxial with the evaporator cylinder.

[0014] The beneficial effects of the present invention are:

[0015] The distributor enables the refrigerant to be evenly distributed within the tubes. The Bernoulli equation is used to change the refrigerant's velocity and pressure, altering its flow rate and macroscopic flow state, creating a gas-liquid two-phase mixture. This mixture has a Prandtl number much lower than that of the liquid phase (taking R134a at a saturation temperature of 5°C as an example, the Prandtl number of pure liquid is 3.77, while that of pure gas is 0.84. The gas-liquid two-phase flow created by the distributor and the equalizing tube / mixing orifice plate within the tube bundle has a Prandtl number between 1.47 and 0.88). This allows for full contact with the heat exchange tube bundle area, achieving efficient heat exchange and improving heat transfer performance. This low Prandtl number operation significantly reduces the refrigerant charge by 40-60% compared to traditional flooded evaporators while ensuring the required cooling capacity. This reduces costs, reduces refrigerant erosion damage to equipment to a certain extent, reduces wear on the heat exchange tube bundle, and extends the service life of equipment. This device has great application market prospects in the field of refrigeration and heat exchangers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a schematic diagram of the assembly structure of a low Prandtl number distributor of the present invention.

[0017] Figure 2 This is a front view of a low Prandtl number distributor of the present invention.

[0018] Figure 3 for Figure 2 AA cross-sectional view.

[0019] Figure 4 for Figure 3 BB cross-sectional view.

[0020] Figure 5 for Figure 4 A partial enlarged view of .

[0021] Among them: bottom plate 1; bottom plate hole 1.1; inner partition 2; inner partition with hole section 2.1; guide plate 3; acceleration plate 4; acceleration plate hole 4.1; deceleration plate 5; deceleration plate hole 5.1; end plate 6; guide partition 7; guide cavity 8; acceleration cavity 9; deceleration cavity 10; pad 11. DETAILED DESCRIPTION

[0022] See also Figure 1-5 The present invention relates to a low Prandtl number distributor, which is installed at the bottom of the evaporator and includes a bottom plate 1, an inner partition plate 2, a guide plate 3, an acceleration plate 4, a deceleration plate 5, an end plate 6 and a guide partition plate 7. Between the two end plates 6 arranged on the left and right, the bottom plate 1, the inner partition plate 2, the guide plate 3, the acceleration plate 4 and the deceleration plate 5 are arranged in sequence from bottom to top. A plurality of acceleration plate holes 4.1 are evenly distributed on the acceleration plate 4, and a plurality of deceleration plate holes 5.1 are evenly distributed on the deceleration plate 5. The inner partition plate 2, the guide plate 3 and the two end plates 6 form a guide cavity 8, the guide plate 3, the acceleration plate 4 and the two end plates form an acceleration cavity 9, the guide cavity 8 and the acceleration cavity 9 are connected, and the acceleration plate 4, the deceleration plate 5 and an end plate 6 form a deceleration cavity 10.

[0023] The deceleration chamber 10 is open, so that the distributor has the function of oil concentration management, such as Figure 4 and Figure 5 As shown, the deceleration chamber 10 is composed of an acceleration plate 4, a deceleration plate 5 and an end plate 6 on the right side. A gap is left between the end plate 6 on the left side and the deceleration plate 5. Through this design, a high oil concentration is accumulated on the side away from the evaporator outlet, which facilitates the recovery of refrigeration oil from the evaporator.

[0024] The feed chamber is composed of the bottom plate 1, inner baffle 2, and left and right guide baffles 7. The two guide baffles 7 are located inside the two end plates 6. The bottom of the feed chamber formed by the bottom plate 1 is provided with a bottom plate hole 1.1 for connecting to the refrigerant inlet pipe. The top of the feed chamber formed by the inner baffle 2 is provided with an inner baffle perforated section 2.1. Due to the extremely high flow rate and impact pressure of the newly entered refrigerant, the refrigerant entering the feed chamber from the refrigerant inlet pipe is constrained by the left and right guide baffles 7 to pass through the inner baffle perforated section 2.1. Applying the principle of Bernoulli's equation: The speed of fluid passing through the aperture is inversely proportional to the size of the aperture. The increase in the pressure of the fluid at this point decreased, the height Decreased, by reducing the pressure and height, the erosion and deformation of the guide plate 7 in the acceleration chamber, prolong the service life of the distributor.

[0025] The guide plate 3 is welded to the corresponding side end plate 6 at one end, and the other end is left with a fluid turning gap from the corresponding side end plate 6, so that the guide cavity 8 and the acceleration cavity 9 arranged above and below are communicated, the fluid in the guide cavity turns to the acceleration cavity, and the guide cavity 8 and the acceleration cavity 9 are distributed with unequal spacing, the cavity spacing decreases from bottom to top, and the change from 18.5mm to 15.7mm makes the refrigerant flow rate larger, increases the engineering turbulence effect, and realizes the complete mixing of gas-liquid two-phase medium. By reasonably calculating and setting the plate gap (cavity spacing) of the guide cavity and the acceleration cavity, the guide cavity realizes intermittent flow or annular flow, realizes uniform distribution of fluid to each acceleration plate hole, makes the acceleration cavity maintain a certain pressure drop (should not be less than 100KPA), and makes the fluid uniformly and rapidly sprayed from the acceleration plate hole. According to the Reynolds number formula ,( Fluid density, V average flow rate, D hole diameter, Fluid dynamic viscosity) Reynolds number is related to macro flow rate, fluid geometry and fluid properties, this cavity increases the turbulent flow of two-phase body, achieves the purpose of making the refrigerant more uniformly mixed, and forms a low-density two-phase mixture, whose Prandtl number is much lower than that of liquid phase.

[0026] The surface of each plate of the distributor needs to be smooth and deburred, the bottom plate 1 is arc-shaped coaxial with the evaporator cylinder body, and can be completely attached to the bottom of the evaporator cylinder body. The inner partition plate 2, the guide plate 3, the acceleration plate 4 and the deceleration plate 5 are all in the shape of ∧, and the whole distributor is in the shape of triangle, which has the characteristics of stability. The inner partition plate 2, the guide plate 3, the acceleration plate 4 and the deceleration plate 5 are all integrally bent and formed, and the bending angles are consistent. The bending angles can be 45°, 60°, 90° or 120°.

[0027] The bottom plate hole 1.1, the acceleration plate hole 4.1 and the deceleration plate hole 5.1 can be circular, square, rhombic, hexagonal or elliptical in shape according to the use conditions and process processing form needs, and the corresponding hole diameters meet . Among them, the acceleration plate hole 4.1 and the deceleration plate hole 5.1 are arranged in a staggered manner, that is, the projections of the acceleration plate hole 4.1 and the deceleration plate hole 5.1 on the bottom plate 1 do not overlap, which prevents the refrigerant from directly running away from the deceleration plate hole 5.1 after being accelerated by the acceleration cavity 9 and the acceleration plate 4. The deceleration plate hole 5.1 increases the resistance and reduces the jetting force.

[0028] The deceleration plate 5 is tightly fitted with the heat exchange tube bundle support plate in the evaporator cylinder. The refrigerant entering the distributor from the bottom plate hole 1.1 is evenly distributed by the distributor and then contacts the heat exchange tube bundle in the evaporator cylinder with sufficient area for efficient heat exchange.

[0029] Pads 11 are provided between the inner partition 2 and the guide plate 3, between the guide plate 3 and the accelerator plate 4, and between the accelerator plate 4 and the decelerator plate 5. The pads support adjacent plates so that each chamber has sufficient rigidity.

[0030] Working principle:

[0031] The refrigerant enters the distributor through bottom plate hole 1.1, is constrained by left and right guide baffles 7, passes through inner baffle perforated section 2.1, and sequentially enters guide chamber 8 and acceleration chamber 9. After being accelerated by the guides and increased turbulence, it passes through acceleration plate hole 4.1 of acceleration plate 4, achieving uniform mixing of gas and liquid at the same speed. This creates a low-Prandtl number medium with a Prandtl number far lower than that of the liquid phase and as close to that of the gas phase as possible. This significantly improves heat transfer performance and increases heat exchange efficiency while maintaining the same amount of heat exchange. The refrigerant then flows through deceleration chamber 10 and exits steadily through deceleration plate hole 5.1. The refrigerant initially passes through acceleration chamber 9 and acceleration plate 4 at a very high velocity. Direct flow into the evaporator barrel for heat exchange with the heat exchange tubes can easily cause erosion of the heat exchange tube bundle due to excessive flow. Furthermore, excessive refrigerant flow can lead to inadequate heat exchange and waste. The use of deceleration chamber 10 and deceleration plate 5 in the low-Prandtl number distributor ensures uniform and stable refrigerant outflow, improving product heat exchange performance and achieving efficient refrigerant utilization.

[0032] The use of the distributor allows the refrigerant to be evenly distributed in the tube, using the principle of Bernoulli equation This causes the refrigerant to change in velocity and pressure, altering its flow rate and macroscopic flow state, creating a gas-liquid two-phase mixture with a Prandtl number much lower than the liquid phase, allowing for full contact with the heat exchange tube bundle area, achieving efficient heat exchange and improving heat transfer performance. In engineering applications, we prefer fluids with low Prandtl numbers, characterized by low viscosity, low specific heat capacity, and high thermal conductivity. The special structure of the distributor ensures that the refrigerant has low Prandtl numbers and is evenly distributed, improving heat transfer performance.

[0033] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A low Prandtl number distributor, which is installed at the bottom of the evaporator, characterized in that: It includes a bottom plate, an inner partition, a guide plate, an acceleration plate, a deceleration plate and an end plate. Between the two end plates arranged on the left and right, there are arranged a bottom plate, an inner partition, a guide plate, an acceleration plate and a deceleration plate from bottom to top. There are several acceleration plate holes evenly distributed on the acceleration plate, and there are several deceleration plate holes evenly distributed on the deceleration plate. The inner partition, the guide plate and the two end plates form a guide cavity, the guide plate, the acceleration plate and the two end plates form an acceleration cavity, the guide cavity and the acceleration cavity are connected, and the acceleration plate, the deceleration plate and one end plate form a deceleration cavity.

2. A low Prandtl number distributor according to claim 1, characterized in that: One end of the guide plate is welded to the end plate on the corresponding side, and a fluid turning gap is left between the other end and the end plate on the corresponding side, so that the acceleration chamber and the guide chamber arranged above and below are connected, and the fluid in the guide chamber turns and flows to the acceleration chamber.

3. A low Prandtl number distributor according to claim 1 or 2, characterized in that: The guide cavity and the acceleration cavity are distributed at unequal intervals, and the intervals between the two cavities decrease from bottom to top.

4. The low Prandtl number distributor according to claim 1, characterized in that: The inner partition, guide plate, acceleration plate and deceleration plate are all in a ∧ shape and are formed by integral bending, with the bending angles being consistent.

5. The low Prandtl number distributor according to claim 4, characterized in that: The bending angles of the inner partition, guide plate, acceleration plate and deceleration plate are 45°, 60°, 90° or 120°.

6. The low Prandtl number distributor according to claim 1, characterized in that: The accelerator plate hole and the decelerator plate hole are staggered.

7. The low Prandtl number distributor according to claim 1, characterized in that: The bottom plate, inner baffle and left and right guide baffles form a feed cavity. The two guide baffles are arranged on the inner sides of the two end plates. The bottom of the feed cavity formed by the bottom plate is provided with a bottom plate hole, and the top of the feed cavity formed by the inner baffle is provided with an inner baffle with a hole section.

8. The low Prandtl number distributor according to claim 1, characterized in that: Pads are provided between the inner partition and the guide plate, between the guide plate and the acceleration plate, and between the acceleration plate and the deceleration plate, and the adjacent plates are supported by the pads.

9. The low Prandtl number distributor according to claim 1, characterized in that: The bottom plate is in an arc shape coaxial with the evaporator cylinder.

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