Self-driven vapor-liquid separation enhanced condensation heat transfer printed circuit board type condenser

Abstract

The invention discloses a self-driven vapor-liquid separation enhanced condensation heat transfer printed circuit board type condenser which comprises a heat exchange core body, a cold and hot side working medium inlet and outlet header, a cold and hot side working medium inlet and outlet connector and a hot side working medium non-condensable gas extraction opening. And the heat exchange core body is formed by sequentially stacking a condensation plate through which a hot working medium flows and a heat exchange plate through which a cold working medium flows. The condensation plate through which the hot-side working medium flows is composed of a plurality of reinforced condensation units, and the heat exchange plate through which the cold-side working medium flows is composed of a plurality of parallel flow channels. According to the condenser, vapor-liquid separation can be achieved in time in a self-driven mode by strengthening centrifugal force induced by a condensation unit structure, condensate is gradually discharged into a specially-arranged liquid discharging channel, and therefore the problem of condensation heat transfer deterioration caused by a water logging phenomenon caused by condensation in a micro channel is effectively solved; therefore, the condensing efficiency of the condenser is remarkably improved, and the condenser is high in design flexibility and can meet industrial application scenes in a wider range.

Description

Technical Field

[0001] The present invention relates to the field of energy power and high-end electronic equipment efficient and compact heat exchange technology, and in particular to a microchannel diffusion welded plate condenser with multiple drainage holes for coordinated directional transport and step-by-step drainage to enhance condensation heat transfer. Background Art

[0002] With the transformation and upgrading of energy at home and abroad, in order to improve energy utilization, the temperature of heat sources in energy systems has generally increased, and the advantages of the Brayton cycle over the steam Rankine cycle are prominent. In applications where the ambient temperature is low, the cold end of the Brayton cycle is designed to be below the saturation temperature to improve the system cycle efficiency. Unlike the steam Rankine cycle, the Brayton cycle has the characteristics of a low pressure ratio and a higher cold end pressure. Taking the Brayton cycle of carbon dioxide as an example, the cold end pressure is around 70 bar. At this time, the condenser usually needs to use a microchannel compact heat exchanger with excellent pressure resistance and heat transfer performance. When the working fluid flows and condenses in the microchannel compact heat exchanger, as the condensation proceeds, the condensate gradually increases and completely covers the heat exchange surface of the tiny channels, resulting in flooding and deterioration of condensation heat transfer. Summary of the invention

[0003] The present invention aims to solve the problem of deteriorated condensation heat transfer in existing micro-channel condensers and propose a self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser.

[0004] The present invention provides the following technical solutions:

[0005] A self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board type condenser comprises a heat exchange core, a hot working medium side inlet header, a hot working medium side outlet header, a cold working medium side inlet header, a cold working medium side outlet header, a hot working medium side inlet pipe, a hot working medium side outlet pipe, a cold working medium side inlet pipe and a cold working medium side outlet pipe, the heat exchange core is composed of a condensation plate through which the hot side working medium flows and a heat exchange plate through which the cold side working medium flows, which are stacked in sequence and are composed of cover plates on the upper and lower bottom surfaces, the condensation plate through which the hot side working medium flows is composed of a plurality of enhanced condensation units, the enhanced condensation units are composed of a plurality of zigzag condensation flow channels with drainage holes and a drainage channel, and a plurality of zigzag condensation flow channels are arranged on each zigzag condensation flow channel. A drain hole is formed, and the drain hole is located downstream of the downward bend of the zigzag flow channel. Several zigzag condensation flow channels with drain holes are connected through the drain holes, and the last zigzag condensation flow channel with drain holes is connected to the drain channel through the drain hole; a filling block is arranged at one end of the hot working medium inlet of the drain channel; a cold working medium flow channel is arranged on the heat exchange plate through which the cold side working medium flows; the hot working medium side inlet header is connected to the inlet of the enhanced condensation unit of the condensation plate, the hot working medium side outlet header is connected to the outlet of the enhanced condensation unit of the condensation plate, the cold working medium side inlet header is connected to the inlet of the cold working medium flow channel of the heat exchange plate, and the cold working medium side outlet header is connected to the outlet of the cold working medium flow channel of the heat exchange plate.

[0006] In response to the deterioration of condensation heat transfer in the cold end condenser of the Brayton cycle, the inventor discovered that there is a regularly distributed pressure field in the curved microchannel and the phenomenon of liquid accumulation caused by centrifugal force at the bend. By cleverly designing drainage holes and dedicated drainage channels, the above-mentioned self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser was proposed. The enhanced condensation condenser can effectively alleviate the flooding phenomenon in the microchannel, avoid the deterioration of condensation heat transfer, and significantly improve the efficiency of the condenser.

[0007] The equivalent hydraulic diameter of the drainage hole is 0.5-2 mm, and the azimuth angle of the drainage hole is 130-170°.

[0008] The equivalent hydraulic diameter of the zigzag condensation flow channel and the drainage channel is 1-5 mm, the longitudinal period length of the zigzag condensation flow channel is 5-40 mm, and the bending angle of the zigzag condensation flow channel is 10-50°.

[0009] The cross-sectional shapes of the broken-line condensation flow channel and the drainage channel are semicircular.

[0010] The hot working medium side inlet header is provided with a hot side working medium non-condensable gas extraction port.

[0011] The condensation plates through which the hot side working medium flows and the heat exchange plates through which the cold side working medium flows should be placed in a manner that ensures that the direction of the lateral component of gravity along the condensation plates is consistent with the direction of the condensation flow channel in the enhanced condensation unit pointing to the drainage flow channel.

[0012] The zigzag condensation flow channel, the drainage channel and the drainage hole on the condensation plate through which the hot side working medium flows are formed by photochemical etching.

[0013] The cold side working medium flow channel of the heat exchange plate through which the cold side working medium flows includes a fin-type straight flow channel, a bent flow channel or an open hole enhanced flow channel formed by chemical etching or stamping.

[0014] The materials of the condensation plate through which the hot side working medium flows and the heat exchange plate through which the cold side working medium flows are metal materials or non-metal materials.

[0015] The condensing plates through which the hot side working medium flows and the heat exchange plates through which the cold side working medium flows are periodically stacked and then formed into a heat exchange core through a diffusion welding process.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) A self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser can effectively alleviate the problem of water flooding caused by condensation in micro-channels and the resulting deterioration of condensation heat transfer by discharging condensate into the drainage channel in a timely manner. The newly invented condenser can improve the condensation efficiency by about 10%-25% compared with the traditional condenser.

[0018] (2) A self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser can increase the volume power density by about 5%-20% compared with the traditional condenser. At the same time, the newly invented condenser is provided with a non-condensable gas exhaust port to facilitate the timely discharge of non-condensable gas in the condenser and maintain the working pressure and heat exchange efficiency of the condenser.

[0019] (3) The drainage holes in the condensing flow channel of a printed circuit board condenser with self-driven vapor-liquid separation and enhanced condensation heat transfer can enhance the uniformity of flow distribution between tiny channels, and reduce the pressure loss caused by uneven flow distribution in traditional plate condensers by about 5%-30%. At the same time, the flexible arrangement of the drainage holes greatly improves the design flexibility of the newly invented condenser, which can meet a wider range of industrial application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a printed circuit board type condenser for self-driven vapor-liquid separation and enhanced condensation heat transfer;

[0021] Figure 2 yes Figure 1 Exploded diagram of

[0022] Figure 3 A schematic diagram of the structure of a condensing plate through which a hot-side working medium flows in a printed circuit board type condenser for self-driven vapor-liquid separation and enhanced condensation heat transfer;

[0023] Figure 4 A schematic diagram of the heat exchange plate structure through which the working medium flows on the cold side of a printed circuit board type condenser for self-driven vapor-liquid separation and enhanced condensation heat transfer;

[0024] Figure 5 It is an enlarged diagram of the drainage hole structure of the condensing plate through which the hot side working medium flows in a printed circuit board type condenser with self-driven vapor-liquid separation and enhanced condensation heat transfer, and a diagram with structural parameter annotations;

[0025] Figure 6 It is a schematic diagram of the structure of the condensing plate through which the hot side working medium flows in an embodiment of a printed circuit board type condenser for self-driven vapor-liquid separation and enhanced condensation heat transfer;

[0026] Figure 7 A schematic diagram of an embodiment of a printed circuit board type condenser for self-driven vapor-liquid separation and enhanced condensation heat transfer and a performance testing platform;

[0027] Figure 8 The vapor-liquid phase distribution diagram and wall accumulation condition of the traditional printed circuit board type condenser without self-driven vapor-liquid separation;

[0028] Fig. 9The figures are the working medium flow rate and liquid discharge diagram in the flow channel of a traditional printed circuit board type condenser without self-driven vapor-liquid separation and a printed circuit board type condenser with self-driven vapor-liquid separation.

[0029] In the figure: 101 is a heat exchange core; 101-1 is a heat exchange core cover; 101-2 is a condensation plate; 101-3 is a heat exchange plate; 102 is an inlet header on the hot working medium side; 103 is an outlet header on the hot working medium side; 104 is an inlet header on the cold working medium side; 105 is an outlet header on the cold working medium side; 106 is an inlet pipe on the hot working medium side; 107 is an outlet pipe on the hot working medium side; 108 is an inlet pipe on the cold working medium side; 109 is an outlet pipe on the cold working medium side; 110 is a non-condensable gas extraction port; 201 is an enhanced condensation unit; 201-1 is the first condensation flow channel; 201-2 is the second condensation flow channel; 201-n is the nth condensation flow channel; 202 is a drainage channel; 203 is a filling block at the inlet of the drainage channel; 204 is a drainage hole. DETAILED DESCRIPTION

[0030] In order to deepen the understanding of the present invention, the present invention is further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0031] A self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board type condenser, such as Figure 1 , Figure 2 As shown, it includes a heat exchange core 101, a hot working medium side inlet header 102, a hot working medium side outlet header 103, a cold working medium side inlet header 104, a cold working medium side outlet header 105, a hot working medium side inlet pipe 106, a hot working medium side outlet pipe 107, a cold working medium side inlet pipe 108, a cold working medium side outlet pipe 109, and a non-condensable gas exhaust port 110. The heat exchange core is connected to the header, and the joint is set on the header. The heat exchange core is stacked in sequence by 20 layers of condensation plates 101-2 through which the hot side working medium flows and 20 layers of heat exchange plates 101-3 through which the cold side working medium flows, and are diffusely welded together with the cover plates 101-1 on the upper and lower bottom surfaces. The condensation plates 101-2 and the heat exchange plates 101-3 are respectively as shown in Figure 6 and Figure 4 The condensation plate 101-2 is composed of a plurality of enhanced condensation units 201, each of which includes a plurality of condensation channels and a drainage channel. The channel structure and drainage hole structure in the enhanced condensation unit are shown in FIG. Figure 5 As shown, α is the channel bending angle, P L is the longitudinal period length of the flow channel, D is the equivalent hydraulic diameter of the drainage hole, and θ is the azimuth angle of the drainage hole. The equivalent hydraulic diameter of the condensation flow channel is 1-5mm, and the longitudinal period length of the condensation flow channel is P LThe equivalent hydraulic diameter D of the drainage hole is 0.5-2 mm, and the azimuth angle θ of the drainage hole is 130-170°.

[0032] In one embodiment, the condensation panel 101 - 2 is composed of two groups of enhanced condensation units 201 .

[0033] In one embodiment, each group of enhanced condensation units 201 includes four condensation channels and one drainage channel, and no drainage holes are arranged in the first longitudinal period along the flow inlet and outlet, and drainage holes are arranged in other periods according to the present invention.

[0034] In one embodiment, the cross-sectional shape of the condensation flow channel is a semicircle with a diameter of 2 mm, the flow channel bending angle α is 30°, and the longitudinal pitch P L The opening width D is 10 mm, the opening width D is 1.31 mm, and the opening angle θ is 158.54°. In addition, the heat exchange plate 101 - 3 is arranged with 9 parallel straight flow channels that are chemically etched, and the cross-sectional shape of the flow channel is a semicircle with a diameter of 2 mm.

[0035] The condensation plate 101-2 through which the hot side medium flows and the heat exchange plate 101-3 through which the cold side medium flows are made of 316L stainless steel, and the flow channel is formed by chemical etching process, and the condenser core is formed by diffusion welding process. The heat exchange core is connected to the header, and the joint is set on the header.

[0036] The working principle and working process of the above embodiment are as follows: the hot side steam under different working conditions enters the condensation flow channel through the hot working medium side inlet pipe 106 and the hot working medium side inlet header 102 to exchange heat with the cold side working medium and condense. Under the action of the inertial force, centrifugal force and gravity of the curved flow channel, the condensate is discharged step by step to the lower flow channel through the arranged drainage holes, and finally discharged into the dedicated drainage channel. Through drainage, the thickness of the film-like condensation liquid film in the condensation flow channel is effectively reduced, the condensation deterioration problem caused by flooding is significantly alleviated, the condensation thermal resistance is reduced, and the condensation efficiency is improved. At the same time, when the condensate flows downward through the drainage hole, it will collide with the wall of the lower flow channel. The larger condensate droplets are broken into small droplets, which will increase the liquid film disturbance to a certain extent. The above two effects can improve the heat exchange efficiency of the condenser. When the non-condensable gas in the steam accumulates to a certain extent, the non-condensable gas is exhausted through the exhaust hole 110 to improve the adverse effects of the non-condensable gas on the condenser.

[0037] The above embodiments were tested for performance. Figure 7As shown, the test platform consists of two parts, left and right, with the test sample 600 of the embodiment in the middle. The right side is the hot side subsystem, the working fluid is carbon dioxide, and the right part is stabilized at 6.0 MPa by the regulator 611. The carbon dioxide is driven by the circulation pump 616 to enter the flow meter 618 and the regenerator 613 for reheating, and then enters the heater 612 to be heated to an overheated state of 28°C, and then the superheated carbon dioxide enters the embodiment sample 600 to be cooled, and the cooled carbon dioxide is then reheated by the regenerator 613 and cooled by the cooler 614 before returning to the circulation pump 616; the left side is the cold side subsystem, the working fluid is cooling water, and the left part is stabilized at 0.6 MPa by the regulator 621. The cooling water is driven by the circulation pump 625 to enter the flow meter 627 and the regenerator 623 for reheating, and then enters the heater 629 to be heated to 20°C, and then enters the embodiment sample 600 to cool the hot side carbon dioxide, and the heated cooling water is then reheated by the regenerator 623 and cooled by the cooler 624 before returning to the circulation pump 625, and the inlet and outlet temperatures and pressure drops of the embodiment sample are measured at the same time. The average equivalent convection heat transfer coefficient and the average equivalent resistance coefficient are calculated according to the following formula:

[0038]

[0039] Where U is the average equivalent convection heat transfer coefficient, Q is the heat transfer of the sample in the embodiment, ΔT ln is the average logarithmic temperature difference, λ is the average equivalent resistance coefficient, ΔP is the pressure drop on the carbon dioxide side, L is the flow channel length, D is the equivalent hydraulic diameter of the flow channel, ρ is the average equivalent density based on the homogeneous flow model, and u is the average flow velocity based on the average equivalent density.

[0040] Through the performance test, under the above temperature and pressure regulation, the mass flow rate of carbon dioxide side is 1051kg / (m 2 s), cooling water side mass flow rate 1509kg / (m 2 s), the average equivalent convection heat transfer coefficient is 7239W / (m 2 ·K), and the average equivalent resistance coefficient is 0.014. When the geometric parameters and working parameters remain unchanged, the test results of the traditional flow channel flow condensation are as follows: the average equivalent convection heat transfer coefficient is 6320W / (m 2 ·K), average equivalent resistance coefficient 0.0163. Compared with the traditional printed circuit board type condenser, the average equivalent convection heat transfer coefficient of the present invention is increased by 14.5%, and the average equivalent resistance coefficient is reduced by 14.1%.

[0041] At 6.5MPa, 1097kg / (m 2 ·s) as an example, a self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser embodiment and traditional flow channel condensation heat transfer simulation results are shown in the figure Figure 8 and Fig. 9 As shown, from Figure 8 The liquid film adhesion phenomenon of the traditional flow channel can be clearly found in Fig. 9 In the figure, we can see the process of carbon dioxide condensation liquid being discharged through the drain hole under the driving force of centrifugal force in the embodiment of the present invention. The average condensation convection heat transfer coefficient of the traditional flow channel under this condition is 6490W / (m 2 ·K), flow pressure loss coefficient 0.016; the average condensation convection heat transfer coefficient of the printed circuit board type condenser embodiment of the present invention for self-driven vapor-liquid separation and enhanced condensation heat transfer is 7508W / (m 2 ·K), the flow pressure loss coefficient is 0.0145. The calculation results show that under this working condition, the condensation efficiency of the present invention is improved by 15.7% compared with the traditional condenser, and the working fluid flow pressure loss is reduced by 9.4%. When the mass flow rate of carbon dioxide steam is increased to 1648kg / (m 2 ·s), the average condensation convection heat transfer coefficient of the traditional flow channel under this condition is 8391W / (m 2 ·K), flow pressure loss coefficient 0.011; the average condensation convection heat transfer coefficient of the printed circuit board type condenser embodiment of the present invention for self-driven vapor-liquid separation and enhanced condensation heat transfer is 10480W / (m 2 ·K), the flow pressure loss coefficient is 0.0077, and the calculation results show that under this working condition, the condensation efficiency of the present invention is improved by 24.9% compared with the traditional condenser, and the working fluid flow pressure loss is reduced by 30.1%. Due to the improvement of the heat transfer capacity of the self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser of the present invention, the required condenser core part volume is reduced under the same heat load, and the head pipe volume remains basically unchanged. At this time, the volume power density of the self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser is increased by about 20.3% compared with the traditional condenser.

[0042] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to allow relevant persons familiar with this technology to have a deep understanding of the implementation process. However, the above content does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser, comprising a heat exchange core, a hot working medium side inlet header, a hot working medium side outlet header, a cold working medium side inlet header, a cold working medium side outlet header, a hot working medium side inlet pipe, a hot working medium side outlet pipe, a cold working medium side inlet pipe and a cold working medium side outlet pipe, characterized in that: The heat exchange core is composed of a condensation plate through which the hot side working medium flows and a heat exchange plate through which the cold side working medium flows, which are stacked in sequence and are composed of cover plates on the upper and lower bottom surfaces. The condensation plate through which the hot side working medium flows is composed of a plurality of enhanced condensation units, and the enhanced condensation units are composed of a plurality of zigzag condensation channels with drainage holes and a drainage channel. A plurality of drainage holes are arranged on each zigzag condensation channel, and the drainage holes are located downstream of the downward bend of the zigzag channel. A plurality of zigzag condensation channels with drainage holes are connected through the drainage holes. Finally, A zigzag condensation flow channel with a drainage hole is connected to the drainage channel through the drainage hole; a filling block is arranged at one end of the hot working medium inlet of the drainage channel; a cold working medium flow channel is provided on the heat exchange plate through which the cold side working medium flows; the hot working medium side inlet header is connected to the inlet of the enhanced condensation unit of the condensation plate, the hot working medium side outlet header is connected to the outlet of the enhanced condensation unit of the condensation plate, the cold working medium side inlet header is connected to the inlet of the cold working medium flow channel of the heat exchange plate, and the cold working medium side outlet header is connected to the outlet of the cold working medium flow channel of the heat exchange plate.

2. A self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The equivalent hydraulic diameter of the drainage hole is 0.5-2 mm, and the azimuth angle of the drainage hole is 130-170°.

3. A self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 2, characterized in that: The equivalent hydraulic diameter of the zigzag condensation flow channel and the drainage channel is 1-5 mm, the longitudinal period length of the zigzag condensation flow channel is 5-40 mm, and the bending angle of the zigzag condensation flow channel is 10-50°.

4. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The cross-sectional shapes of the broken-line condensation flow channel and the drainage channel are semicircular.

5. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The hot working medium side inlet header is provided with a hot side working medium non-condensable gas extraction port.

6. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The condensation plates through which the hot side working medium flows and the heat exchange plates through which the cold side working medium flows should be placed in a manner that ensures that the direction of the lateral component of gravity along the condensation plates is consistent with the direction of the condensation flow channel in the enhanced condensation unit pointing to the drainage flow channel.

7. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The zigzag condensation flow channel, the drainage channel and the drainage hole on the condensation plate through which the hot side working medium flows are formed by photochemical etching.

8. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The cold side working medium flow channel of the heat exchange plate through which the cold side working medium flows includes a fin-type straight flow channel, a bent flow channel or an open hole enhanced flow channel formed by chemical etching or stamping.

9. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The materials of the condensation plate through which the hot side working medium flows and the heat exchange plate through which the cold side working medium flows are metal materials or non-metal materials.

10. The self-driven vapor-liquid separation and condensation heat transfer enhanced printed circuit board condenser according to claim 1, characterized in that: The condensing plates through which the hot side working medium flows and the heat exchange plates through which the cold side working medium flows are periodically stacked and then formed into a heat exchange core through a diffusion welding process.

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