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

Abstract

The present invention discloses a self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser, which includes a heat exchange core, hot and cold side working medium inlet and outlet headers, hot and cold side working medium inlet and outlet joints, and a hot side working medium non-condensable gas extraction port. The heat exchange core is formed by stacking condensation plates through which the hot working medium flows and heat exchange plates through which the cold working medium flows. The condensation plates through which the hot side working medium flows are composed of a number of enhanced condensation units, and the heat exchange plates through which the cold side working medium flows are composed of a number of parallel flow channels. The condenser can achieve vapor-liquid separation in a self-driven manner in a timely manner through the centrifugal force induced by the enhanced condensation unit structure, and gradually discharge the condensate into a dedicated drainage channel, thereby effectively suppressing the deterioration of condensation heat transfer caused by flooding caused by condensation in the tiny channel, thereby significantly improving the condensation efficiency of the condenser. The condenser design is relatively flexible and can meet a wider range of industrial application scenarios.

Description

Technical Field

[0001] The present invention relates to the field of efficient and compact heat exchange technology for energy power and high-end electronic equipment, 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 energy transformation and upgrading at home and abroad, in order to improve energy utilization, the temperature of the heat source of the energy system has generally increased, and the advantages of the Brayton cycle over the steam Rankine cycle have become more 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 low pressure ratio and high 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 adopt 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 channel, resulting in water 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 proposes 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 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, the heat exchange core is composed of condensation plates through which the hot side working medium flows and heat exchange plates 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 plates through which the hot side working medium flows are composed of a number of enhanced condensation units, the enhanced condensation units are composed of a number of zigzag condensation flow channels with drainage holes and a drainage channel, and a number of zigzag condensation flow channels are arranged on each zigzag condensation flow channel. There is a drain hole, 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; the drain channel is provided with a filling block at one end of the hot working medium inlet; a cold-test 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 condensing unit of the condensing plate, the hot working medium side outlet header is connected to the outlet of the enhanced condensing unit of the condensing plate, the cold working medium side inlet header is connected to the inlet of the cold-test 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-test working medium flow channel of the heat exchange plate.

[0006] To address the deterioration of condensation heat transfer in the cold-end condenser of a Brayton cycle, the inventors discovered that a regularly distributed pressure field exists within the curved microchannels, as well as liquid accumulation caused by centrifugal force at the bends. Through ingeniously designed drainage holes and dedicated drainage channels, they developed the self-driven vapor-liquid separation, PCB-type condenser with enhanced condensation heat transfer. This enhanced condenser effectively alleviates flooding within the microchannels, prevents deterioration of condensation heat transfer, and significantly improves condenser efficiency.

[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 degrees.

[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 such 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 broken-line 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 channels of the heat exchange plate through which the cold side working medium flows include fin-type straight channels formed by chemical etching or stamping, bent channels or perforated enhanced channels.

[0014] The materials of the condensing 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 small channels and the resulting deterioration of condensation heat transfer by discharging condensate into the drainage channel in a timely manner. This newly invented condenser can improve the condensation efficiency by about 10%-25% compared with traditional condensers.

[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, which facilitates the timely discharge of non-condensable gas in the condenser and facilitates the maintenance of the condenser working pressure and heat exchange efficiency.

[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 the needs of a wider range of industrial application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 2 yes Figure 1 Exploded diagram;

[0022] Figure 3 A schematic diagram of the condensing plate structure through which the 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 of a self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser with a cold side working medium flowing through it;

[0024] Figure 5 This 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, as well as a diagram with structural parameters;

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

[0026] Figure 7 A schematic diagram of an embodiment of a printed circuit board 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 situation of the traditional printed circuit board condenser without self-driven vapor-liquid separation;

[0028] Figure 9The figures show the working medium flow rate and liquid discharge in the flow channels 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 the heat exchange core; 101-1 is the heat exchange core cover; 101-2 is the condensation plate; 101-3 is the heat exchange plate; 102 is the hot working medium side inlet header; 103 is the hot working medium side outlet header; 104 is the cold working medium side inlet header; 105 is the cold working medium side outlet header; 106 is the hot working medium side inlet pipe; 107 is the hot working medium side outlet pipe; 108 is the cold working medium side inlet pipe; 109 is the cold working medium side outlet pipe; 110 is the non-condensable gas extraction port; 201 is the 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 the drainage channel; 203 is the filling block at the inlet of the drainage channel; 204 is the drainage hole. DETAILED DESCRIPTION

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

[0031] A self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board 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 extraction 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 FIG. Figure 6 and Figure 4 The condensation plate 101-2 is composed of several groups of enhanced condensation units 201, each group of enhanced condensation units 201 includes several condensation channels and one 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 P is 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 sets of enhanced condensation units 201 .

[0033] In one embodiment, each group of enhanced condensing units 201 includes four condensing channels and one drainage channel. 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-section of the condensation channel is a semicircle with a diameter of 2 mm, the channel bending angle α is 30°, and the longitudinal pitch P is L The opening width D is 10 mm, the opening angle θ is 158.54°. In addition, the heat exchange plate 101-3 is provided with 9 parallel straight flow channels formed by chemical etching, and the cross-sectional shape of the flow channel is a semicircle with a diameter of 2 mm.

[0035] The condenser plates 101-2, through which the hot-side working medium flows, and the heat exchange plates 101-3, through which the cold-side working medium flows, are both made of 316L stainless steel. The flow channels are shaped through a chemical etching process, and the condenser core is formed through a diffusion welding process. The heat exchange core is connected to the header, and the connector is installed on the header.

[0036] The working principle and workflow of the above embodiment are as follows: hot-side steam under different working conditions enters the condensation channel through the hot medium side inlet pipe 106 and the hot medium side inlet header 102, exchanges heat with the cold medium, and condenses. Under the action of the inertial force, centrifugal force, and gravity of the curved channel, the condensate is discharged step by step to the lower channel through the arranged drainage holes, and finally discharged into the dedicated drainage channel. By draining the liquid, the thickness of the film-like condensation liquid film in the condensation 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 thereby improved. At the same time, when the condensate flows downward through the drainage holes, it will collide with the wall of the lower channel. The breakage of larger condensate droplets into small droplets will increase the liquid film disturbance to a certain extent. Both of the above 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, the left and the 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 a superheated state of 28°C. The superheated carbon dioxide then enters the embodiment sample 600 to be cooled. 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. 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. Then it enters the embodiment sample 600 to cool the hot side carbon dioxide. The heated cooling water is then reheated by the regenerator 623 and cooled by the cooler 624 before returning to the circulation pump 625. At the same time, the inlet and outlet temperatures and pressure drops of the embodiment sample are measured. 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, 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 an average equivalent resistance coefficient of 0.014. When the geometric parameters and operating parameters remain unchanged, the traditional flow channel flow condensation test results show that the average equivalent convection heat transfer coefficient is 6320W / (m 2 Compared with the traditional printed circuit board 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] 1097kg / (m2 at 6.5MPa) 2 Taking the condensation of carbon dioxide vapor in the presence of s) as an example, the simulation results of a printed circuit board condenser embodiment with self-driven vapor-liquid separation and enhanced condensation heat transfer are shown in the figure below. Figure 8 and Figure 9 As shown, from Figure 8 The liquid film adhesion phenomenon of the traditional flow channel can be clearly found in the Figure 9 In the embodiment of the present invention, the process of carbon dioxide condensation liquid being discharged through the drain hole under the driving force of centrifugal force can be seen. Under this working condition, the average condensation convection heat transfer coefficient of the traditional flow channel 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 medium 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), and the flow pressure loss coefficient is 0.0077. Calculation results show that under these operating conditions, the present invention improves condensation efficiency by 24.9% and reduces working fluid flow pressure loss by 30.1% compared to conventional condensers. Due to the improved 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 volume is reduced under the same heat load, while the head and pipe volume remains essentially unchanged. In this case, the volumetric power density of the self-driven vapor-liquid separation and enhanced condensation heat transfer printed circuit board condenser is increased by approximately 20.3% compared to conventional condensers.

[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 deeper understanding of the implementation process. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A self-driven printed circuit board condenser with vapor-liquid separation and enhanced condensation heat transfer, 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. The enhanced condensation units are composed of a plurality of zigzag condensation flow channels with drainage holes and a drainage channel. A plurality of drainage holes are arranged on each zigzag condensation flow channel, and the drainage holes are located downstream of the downward bend of the zigzag flow channel. A plurality of zigzag condensation flow 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 condensing unit of the condensing plate, the hot working medium side outlet header is connected to the outlet of the enhanced condensing unit of the condensing 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. The 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. The 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 degrees.

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 broken-line 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.

7. 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 formed by chemical etching or stamping, a bent flow channel or an open hole enhanced flow channel.

8. 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 condensing 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.

9. 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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