Combined type separated heat pipe evaporative condenser
By connecting a combined separate heat pipe heat exchanger in series in a traditional pre-cooled evaporative condenser and replacing it with enhanced heat transfer tubes, the problems of easy scale buildup and insufficient heat transfer area in the condenser are solved, achieving efficient heat transfer and material saving.
Patent Information
- Application Number
- CN202520268289.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2026-01-13
- Estimated Expiration
- 2035-02-19
AI Technical Summary
Traditional evaporative condensers are prone to scale buildup, which reduces the heat transfer coefficient, results in a small heat exchange area per unit volume, and causes them to be heavy. Furthermore, pre-cooling evaporative condensers have not completely solved the problem of scale buildup on the condenser coils.
In a traditional pre-cooled evaporative condenser, a series of combined separate heat pipe heat exchangers are used, and the condenser coils are replaced with enhanced heat transfer tubes. By adopting heat pipe heat exchange technology, a large amount of heat is transferred using the heat pipe working medium under small temperature difference, thus avoiding scale formation in the cooling water.
It improves heat transfer efficiency, increases the heat transfer area for the same volume, reduces metal consumption, and lowers production and operating costs.
Smart Images
Figure CN223795525U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a condenser, and more particularly to a combined split heat pipe evaporative condenser, belonging to the technical field of refrigeration auxiliary equipment. Background Technology
[0002] Traditional evaporative condensers utilize the evaporation of sprayed water outside the condenser coils to absorb heat from the high-temperature gaseous heat source fluid inside the coils, causing the heat source fluid to gradually condense from a gaseous state to a liquid state. Cooling water is pumped to a spray device and sprayed onto the outer surface of the condenser coils to form a water film. A small portion of this cooling water film absorbs heat from the vapor of the heat source fluid inside the coils and evaporates, simultaneously exchanging heat with the rapidly flowing air outside the coils. The heat exchange process is primarily based on latent heat, with sensible heat playing a secondary role, and the heat is carried away by the air. Compared to other types of condensers, traditional evaporative condensers have a higher heat transfer coefficient and higher heat exchange efficiency, making them a highly efficient heat exchange device, and thus widely used in many industrial fields. However, traditional evaporative condensers still have some problems, the most prominent being:
[0003] 1. Scale buildup on condenser coils easily reduces the heat transfer coefficient. Traditional evaporative condensers use circulating cooling water with a high mineral content. Furthermore, the high temperature of the heat source fluid entering the condenser coils makes it easy for these minerals to adhere to the coil surface and form scale. Scale buildup reduces the heat transfer coefficient. To prevent scale formation, the circulating water must be softened, but currently, there is a lack of economical, reliable, and convenient water softening technologies. This scale problem, to some extent, restricts the widespread use of traditional evaporative condensers.
[0004] 2. Traditional evaporative condensers have a relatively small heat exchange area per unit volume, are heavy, and consume a large amount of metal. To facilitate scale removal after buildup, traditional evaporative condensers use smooth tubes for their heat exchange coils. However, because the tube walls are smooth, the cooling water tends to flow in a laminar state outside the tubes, significantly reducing the heat transfer coefficient of the condenser coil. Furthermore, for the same volume, these smooth-tube condenser coils have a small heat exchange area and poor heat exchange efficiency. To achieve condensation, the heat exchange area must be increased, resulting in the large size and weight of traditional evaporative condensers.
[0005] To address the aforementioned problems, a pre-cooled evaporative condenser has been proposed (see attached image). Figure 1This type of evaporative condenser adds a precooler to the traditional evaporative cooler, with the precooler coil made of enhanced heat transfer tubes. The heat source fluid enters the precooler coil for cooling before entering the condenser coil, lowering its temperature to below 50ºC, a temperature where scaling is less likely to occur. However, because the precooler is an air cooler, the inlet air temperature is relatively high, making it difficult to lower the heat source fluid temperature below 50ºC. The problem of scaling on the condenser coil is not completely solved. To facilitate scale removal after scaling, the condenser coil still has to be made of bare tubes. Therefore, the precooled evaporative condenser has not been widely adopted.
[0006] Working principle of pre-cooled evaporative condenser:
[0007] The gaseous heat source fluid enters the precooler coil (b) through the heat source fluid inlet (a) of the precooler coil, exchanges heat with the air outside the precooler coil, and after the temperature drops to a level close to that of water where scaling is not likely, it is discharged from the heat source fluid outlet (c) of the precooler coil and enters the condenser coil (d), where it exchanges heat with the water and air outside the coil. After condensing and releasing heat, the phase becomes liquid and is discharged from the condenser coil (d) through the heat source fluid outlet (e). The water pump (f) pumps the cooling water in the water tank (g) to the sprayer (h), which sprays the cooling water onto the condenser coil (d). A small portion of the water absorbs the heat released by the heat source fluid in the condenser coil (d), and the evaporated phase becomes water vapor, which is then drawn away by the fan (i). The unevaporated water flows back to the water tank (g). The water vapor drawn away by the fan (i) and the water droplets carried in the air are intercepted by the water catcher (j) and return to the water tank (g). Summary of the Invention
[0008] To overcome the shortcomings of traditional evaporative condensers, this invention provides a combined split-heat pipe evaporative condenser with a larger heat exchange area, higher heat exchange efficiency, and no scaling within the same volume. The objective of this invention is achieved through the following technical solution:
[0009] A novel type of evaporative condenser—the combined heat-split heat pipe evaporative condenser—is created by connecting a combined heat-split heat pipe heat exchanger in series between the precooler coil and the condenser coil, while keeping the rest of the structure unchanged. Figure 2 and attached Figure 3 .
[0010] This paper describes a technical upgrade of a traditional evaporative condenser using heat pipe heat exchange technology and shell-and-tube heat exchanger technology. The specific technical solution involves connecting a combined, separate heat pipe heat exchanger in series between the precooler coil and the condenser coil of a traditional precooling evaporative condenser. The condenser coil in the traditional evaporative condenser is replaced with an enhanced heat exchange tube, while other structural elements remain unchanged. The combined, separate heat pipe heat exchanger is composed of two horizontal shell-and-tube heat exchangers connected in series; one serves as the evaporation section of the heat pipe heat exchanger, and the other as the condensation section. The basic working principle of the separate heat pipe heat exchanger is as follows: after evacuating the heat pipes, a certain amount of heat pipe working medium is introduced. In the evaporation section, the working medium liquid in the heat pipe boils and evaporates into a saturated gas upon heating. This saturated gas, carrying heat, rises along the riser pipe to the condensation section under a small pressure difference. In the condensation section, the saturated gas releases heat and condenses back into a liquid, returning to the evaporation section along the downcomer pipe under gravity, forming a closed loop. Heat is continuously transferred from the evaporation section to the condensation section. The heat transfer from the evaporation section to the condensation section is achieved through the vapor-liquid phase transition of the working medium. Because the heat is transferred by saturated vapor, the temperature difference between the evaporation and condensation sections is very small. This means that the heat pipe can transfer a large amount of heat even with a small temperature difference. Due to this characteristic, the temperature of the working medium gas entering the condensation section is relatively low, generally not exceeding the scaling temperature of water. There is no need to worry about scaling of the external circulating cooling water, allowing the heat exchanger to maintain a high heat transfer coefficient. Therefore, the heat exchange coils of a traditional evaporative condenser can be replaced with enhanced heat exchange tubes. Compared to bare tubes, reinforced heat exchange tubes of the same volume greatly increase the heat transfer area and enhance the heat transfer efficiency. The absorption and release of latent heat of phase change is a highly efficient heat transfer process. Therefore, under the same heat exchange capacity, the volume of the condensing coil can be significantly reduced, thus reducing metal consumption.
[0011] The shell side of the evaporator section carries the heat source fluid, and the tube side carries the heat pipe working medium fluid. The shell side of the condenser section carries the heat pipe working medium fluid, and the tube side carries the heat sink fluid. The shell side air inlet of the evaporator section is connected to the air outlet of the precooler coil, and the shell side air outlet of the evaporator section is connected to the air inlet of the condenser. The tube side air outlet of the evaporator section is connected to the shell side air inlet of the condenser section, and the tube side liquid inlet of the evaporator section is connected to the shell side liquid outlet of the condenser section. The cooling water inlet of the condenser section is connected to the water pump outlet, and the cooling water outlet is connected to the water tank.
[0012] In the evaporation section, the heat pipe's working medium evaporates and absorbs heat, which is latent heat transfer with a high heat transfer coefficient. Outside the tube, the heat source fluid is cooled by gas, which is sensible heat transfer with a low heat transfer coefficient. Therefore, enhanced heat transfer measures are taken outside the heat exchange tubes in the evaporation section. In the condensation section, the heat pipe's working medium condenses and releases heat outside the tube, which is latent heat transfer with a high heat transfer coefficient. Inside the tube, cooling water absorbs and cools, which is sensible heat transfer with a relatively low heat transfer coefficient. Therefore, forced heat transfer measures are adopted inside the heat exchange tubes in the condensation section, or bare tubes can be used.
[0013] The working principle of this combined heat pipe evaporative condenser is as follows:
[0014] The high-temperature superheated gas of the heat source fluid enters the precooler (16) through the precooler inlet (17) and exchanges heat with the air outside the tubes of the precooler (16). After releasing heat and cooling down, the heat source fluid exits the precooler (16) through the precooler outlet (9) and then enters the shell side of the shell-and-tube heat exchanger A (2) through the shell-side inlet (8) of the shell side of the shell-and-tube heat exchanger A. It exchanges heat with the heat pipe working medium in the tube side. After the temperature drops below 50ºC, it exits through the shell-and-tube heat exchanger A through the shell-side outlet (10) and enters the condenser (18) through the condenser inlet (11). In the condenser (18), the heat source fluid exchanges heat with the cooling water and air outside the tubes and becomes a liquid at saturation temperature. It is then discharged from the condenser coil (18) through the condenser outlet (19) to complete the condensation process. In the tube side of the shell-and-tube heat exchanger A (2), the working medium of the liquid heat pipe exchanges heat with the heat source fluid outside the tube. After boiling and evaporating into gas, it is discharged from the outlet (4) of the tube side of the shell-and-tube heat exchanger A and enters the shell side of the shell-and-tube heat exchanger B (3) through the inlet (5) of the shell side of the shell-and-tube heat exchanger B. In the shell side of the shell-and-tube heat exchanger B (3), the working medium of the gas heat pipe exchanges heat with the heat sink fluid in the tube side. After releasing latent heat and turning into liquid, it is discharged from the outlet (6) of the shell side of the shell-and-tube heat exchanger B and returns to the tube side of the shell-and-tube heat exchanger A (2) through the inlet (7) of the tube side of the shell-and-tube heat exchanger A, completing one cycle.
[0015] The water pump (13) draws cooling water from the water tank (15) and sends it to the sprayer (20). The sprayer (20) sprays the water onto the coil of the condenser (18). A small portion of the water absorbs the heat released by the heat source fluid and turns into water vapor, which is then drawn away by the fan (21). The air, mixed with water vapor, flows through the precooler (16) and exchanges heat with the heat source fluid in the precooler tubes before being discharged outside the condenser. Most of the unevaporated water flows back to the water tank, and the water vapor and water droplets carried in the air are intercepted by the water catcher (22) and return to the water tank.
[0016] The cooling water inlet (12) of the shell-and-tube heat exchanger B is connected to the outlet pipe of the water pump (13). The cooling water enters the tube side of the shell-and-tube heat exchanger B (3) through the cooling water inlet (12) of the shell-and-tube heat exchanger B, and after exchanging heat with the heat pipe working medium outside the tube side, it returns to the water tank (15) from the cooling water outlet (14) of the shell-and-tube heat exchanger B.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0018] 1. Due to the adoption of heat pipe heat exchange technology, the temperature of the heat source fluid entering the condenser is greatly reduced, solving the problem of scaling of cooling water caused by high heat exchange temperature;
[0019] 2. Due to the reasons mentioned in point 1 above, the condenser heat exchange coil can be made of reinforced heat exchange tubes, which greatly increases the heat transfer area and enhances the heat transfer efficiency under the same volume. Therefore, under the same heat exchange capacity, the volume of the heat exchange coil can be significantly reduced, metal consumption can be reduced, and product production and operating costs can be lowered. Attached Figure Description
[0020] Appendix Figure 1 This is a structural diagram of a pre-cooled evaporative condenser.
[0021] Figure 1 (a) Precooler inlet, (b) Condensing coil, (c) Precooler outlet, (d) Condenser, (e) Condenser outlet, (f) Water pump, (g) Water tank, (h) Sprayer, (i) Fan, (j) Water trap.
[0022] Appendix Figure 2 This is the main view of the combined split heat pipe evaporative condenser structure.
[0023] Appendix Figure 3 This is a side view of a combined split heat pipe evaporative condenser structure.
[0024] Figure 2 , 3 In the middle, (1) pre-cooled evaporative condenser, (2) shell and tube heat exchanger A, (3) shell and tube heat exchanger B, (4) tube side outlet of shell and tube heat exchanger A, (5) shell side inlet of shell and tube heat exchanger B, (6) shell side liquid outlet of shell and tube heat exchanger B, (7) tube side liquid inlet of shell and tube heat exchanger A, (8) shell side inlet of shell and tube heat exchanger A, (9) pre-cooler outlet, (10) shell side outlet of shell and tube heat exchanger A Air inlet, (11) Condenser air inlet, (12) Shell-and-tube heat exchanger B cooling water inlet, (13) Water pump, (14) Shell-and-tube heat exchanger B cooling water outlet, (15) Water tank, (16) Precooler, (17) Precooler air inlet, (18) Condenser, (19) Condenser liquid outlet, (20) Sprayer, (21) Fan, (22) Water trap, (23) Combined split heat pipe heat exchanger.
[0025] The following is in conjunction with the appendix Figure 2 Appendix Figure 3 Explain the structure of the combined split heat pipe evaporative condenser:
[0026] Similar to the structure of a traditional precooled evaporative condenser, the fan (21) of the combined split heat pipe evaporative condenser is located at the top of the condenser. From the fan (21), the precooler (16), water trap (22), sprayer (20), condenser (18), and water tank (15) are arranged in sequence downwards. A combined split heat pipe heat exchanger (23) is connected in series between the air outlet (9) of the precooler (16) and the air inlet (11) of the condenser (18). A water pump (13) is located next to the water tank (15). The water inlet of the water pump (13) is connected to the water tank (15), and the water outlet is connected to the sprayer (20). The combined split heat pipe heat exchanger (23) is composed of two shell and tube heat exchangers: the shell and tube heat exchanger A (2) serves as the heat pipe evaporation section, and the shell and tube heat exchanger B (3) serves as the heat pipe condensation section. The shell-side air inlet (8) of the shell-and-tube heat exchanger A is connected to the precooler outlet (9) of the precooler (16), and the shell-side air outlet (10) of the shell-and-tube heat exchanger A is connected to the air inlet (11) of the condenser (18); the tube-side air outlet (4) of the shell-and-tube heat exchanger A is connected to the shell-side air inlet (5) of the shell-and-tube heat exchanger B, and the shell-side liquid outlet (6) of the shell-and-tube heat exchanger B is connected to the tube-side liquid inlet (7) of the shell-and-tube heat exchanger A; the cooling water inlet (12) of the shell-and-tube heat exchanger B is connected to the outlet pipe of the water pump (13), and the cooling water outlet (14) of the shell-and-tube heat exchanger B is connected to the water tank (15). Detailed Implementation
[0027] The following is in conjunction with the appendix Figure 2 Appendix Figure 3 The present invention is described in the following embodiments:
[0028] This embodiment uses a combined split-type heat pipe evaporator-condenser used in an ammonia refrigeration system as an example to describe the working process. Its design conditions are as follows:
[0029] Summer outdoor calculated dry-bulb temperature for ventilation: 34ºC;
[0030] The average annual outdoor wet-bulb temperature during summer is not guaranteed to be 27ºC (less than 50 hours).
[0031] Summer outdoor relative humidity (calculated): 64%;
[0032] Refrigeration system condensing temperature: 35ºC;
[0033] Refrigeration system refrigerant (heat source fluid): ammonia;
[0034] The heat pipe's working medium is ammonia.
[0035] High-temperature superheated ammonia gas from the refrigeration system enters the precooler (16) through the precooler inlet (17) and exchanges heat with the air outside the tubes of the precooler (16), releasing heat and lowering the temperature. When the temperature drops to 60ºC, the refrigerant ammonia vapor is discharged from the precooler (16) through the precooler outlet (9), and then enters the shell side of the shell-side heat exchanger A (2) through the shell-side inlet (8) of the shell side of the shell-side heat exchanger A, where it exchanges heat with the heat pipe working medium liquid ammonia in the tube side, and the temperature drops to below 50ºC. Then it is discharged from the shell-side outlet (10) of the shell side of the shell-side heat exchanger A and enters the condenser (18) through the condenser inlet (11). In the condenser (18), the refrigerant ammonia vapor exchanges heat with the cooling water and air outside the tubes, becoming a saturated liquid at the condensation temperature, and is discharged from the condenser (18) through the condenser outlet (19), completing the condensation process, and then enters the refrigeration system.
[0036] In the tube side of the shell-and-tube heat exchanger A (2), the heat pipe working medium liquid ammonia exchanges heat with the refrigerant hot ammonia vapor outside the tube. After boiling and evaporating into gas, it is discharged from the tube side outlet (4) of the shell-and-tube heat exchanger A and enters the shell side of the shell-and-tube heat exchanger B (3) through the shell side gas inlet (5). In the shell side of the shell-and-tube heat exchanger B (3), the heat pipe working medium ammonia vapor exchanges heat with the cooling water in the tube side. After releasing the latent heat and changing into a liquid at 40ºC, it is discharged from the shell side outlet (6) of the shell side of the shell-and-tube heat exchanger B and returns to the tube side of the shell-and-tube heat exchanger A (2) through the tube side inlet (7), completing one cycle.
[0037] The cooling water inlet (12) of the shell-and-tube heat exchanger B is connected to the outlet pipe of the water pump (13). The cooling water enters the tube side of the shell-and-tube heat exchanger B (3) through the cooling water inlet (12) of the shell-and-tube heat exchanger B, and after exchanging heat with the heat pipe working medium ammonia gas outside the tube side, it returns to the water tank (15) from the cooling water outlet (14) of the shell-and-tube heat exchanger B.
[0038] The water pump (13) draws cooling water from the water tank (15) and sends it to the sprayer (20). The sprayer (20) sprays the water onto the coil of the condenser (18). A small portion of the water absorbs the heat released by the heat source fluid and turns into water vapor, which is then drawn away by the fan (21). The air, mixed with water vapor, flows through the precooler (16) and exchanges heat with the refrigerant ammonia vapor in the precooler tube before being discharged outside the condenser. Most of the unevaporated water flows back to the water tank, and the water vapor and water droplets carried in the air are intercepted by the water catcher (22) and return to the water tank.
[0039] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed in this utility model, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.
Claims
1. A combined separate heat pipe evaporative condenser, mainly comprising a pre-cooling type evaporative condenser (1), a tube heat exchanger A (2), and a tube heat exchanger B (3), characterized in that: The shell side outlet (6) of the shell side of the shell-and-tube heat exchanger B is connected with the tube side inlet (7) of the tube side of the shell-and-tube heat exchanger A, the shell side inlet (8) of the shell side of the shell-and-tube heat exchanger A is connected with the gas outlet (9) of the pre-cooler, the shell side outlet (10) of the shell side of the shell-and-tube heat exchanger A is connected with the gas inlet (11) of the condenser, the cooling water inlet (12) of the shell-and-tube heat exchanger B is connected with the water outlet pipe of the water pump (13), and the cooling water outlet (14) of the shell-and-tube heat exchanger B is connected with the water tank (15).