Secondary precooling type evaporative condenser
By connecting shell and tube heat exchangers in series in traditional pre-cooled evaporative condensers and switching to enhanced heat transfer pipes, efficient condenser scale prevention and efficient heat transfer are achieved, solving the large scale and volume problems of traditional condensers, reducing production and operation costs.
Patent Information
- Application Number
- CN202510997895.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-20
- Publication Date
- 2025-09-02
AI Technical Summary
Traditional evaporation condensers are prone to scale formation, with reduced heat transfer coefficient, small heat exchange area per unit volume, huge weight, and large metal consumption. The pre-cooled evaporation condensers fail to completely solve the scale formation problem and have low heat exchange efficiency.
In a traditional pre-cooled evaporation condenser, the shell and tube heat exchanger is connected in series, and the condenser coil is changed to a strengthened heat transfer tube. A secondary cooling process is adopted to reduce the temperature of the heat source fluid to about 45°C, avoid scaling, and increase the heat transfer area under the same volume.
Effectively prevent condenser scaling, enhance heat transfer efficiency, reduce condenser volume and metal consumption, and reduce production and operation costs.
Smart Images
Figure CN120576599A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a condenser, in particular to a secondary pre-cooling evaporative condenser, and belongs to the technical field of refrigeration accessory equipment. Background Art
[0002] The traditional evaporative condenser uses the spray water outside the condensing coil to absorb the heat of the high-temperature gaseous heat source fluid inside the coil when it evaporates, so that the heat source fluid gradually cools from the gaseous state and condenses into a liquid state; the cooling water is pumped to the spray device by a water pump and sprayed on the outer surface of the condensing coil to form a water film. A small part of the cooling water film absorbs the heat of the heat source fluid vapor in the tube and evaporates. At the same time, it contacts and exchanges heat with the fast-flowing air outside the tube, completing the heat exchange process mainly with latent heat and supplemented by sensible heat, and the heat is taken away by water vapor and air. Compared with other types of condensers, the traditional evaporative condenser has a higher heat transfer coefficient and higher heat exchange efficiency. It is a device with high heat exchange efficiency and is therefore widely used in many industrial fields. However, there are still some problems with traditional evaporative condensers, the most prominent of which are: 1. Condensing coils are prone to scaling, reducing the heat transfer coefficient. Because traditional evaporative condensers use circulating cooling water, which is high in minerals, and the relatively high temperature of the heat source fluid entering the condensing coils, the minerals in the water are easily adsorbed on the surface of the condensing coils, forming scale. Scaling of the condensing coils reduces the heat transfer coefficient. To prevent scaling, the circulating water must be softened. However, there is currently a lack of economical, reliable, and easy-to-use water softening processes. This scaling problem has, to a certain extent, restricted the widespread use of traditional evaporative condensers.
[0003] 2. Traditional evaporative condensers have a relatively small heat exchange area per unit volume, are heavy, and require a high metal consumption. To facilitate handling after scaling, traditional evaporative condensers use bare tubes for their heat exchange coils. However, due to the smooth surface of bare tubes, cooling water tends to flow in a laminar manner outside the tubes, significantly reducing the heat transfer coefficient of the condenser coils. Furthermore, for a given volume, such bare tubes have a small heat exchange area and relatively low heat transfer efficiency. To achieve condensation, the heat exchange area must be increased, resulting in the bulk and weight of traditional evaporative condensers.
[0004] In order to solve the above problems, some people proposed a pre-cooling evaporative condenser, see attached Figure 1That is, a precooler is added to the traditional evaporative cooler, and the precooler coil is made of enhanced heat transfer tubes. Before the heat source fluid enters the condenser coil, it first enters the precooler coil for cooling, and the temperature is reduced to a temperature at which water is not easily scaled (below 50ºC) before entering the condensing coil for condensation. However, since the precooler is an air cooler, the inlet air temperature is relatively high, and the temperature of the heat source fluid is difficult to drop below 50ºC. The problem of easy scaling of the condensing coil has not been completely solved. In order to make it easier to deal with the scaling of the condensing coil, it is necessary to still use bare tubes to make the condensing coil, which still does not change the problems of relatively small heat exchange area per unit volume, large weight, and high metal consumption. Therefore, the precooling evaporative condenser has not been widely promoted and used.
[0005] Working principle of pre-cooling evaporative condenser: The gaseous heat source fluid enters the precooler coil (b) from the heat source fluid inlet (a) of the precooler coil, exchanges heat with the air outside the precooler coil, and is discharged from the heat source fluid outlet (c) of the precooler coil after the temperature drops to a temperature close to the temperature at which water is not easily scaled, and enters the condenser coil (d), exchanges heat with the water and air outside the coil, condenses and releases heat, and then turns into liquid and is discharged from the condenser coil (d) from the heat source fluid outlet (e) of the condenser coil; the water pump (f) pumps the cooling water in the water tank (g) to the sprayer (h), and the sprayer (h) sprays the cooling water onto the condenser coil (d). After a small part of the water absorbs the heat released by the heat source fluid in the condenser coil (d), it evaporates and turns into water vapor and is extracted by the fan (i), and the unevaporated water flows back to the water tank (g); the water vapor extracted by the fan (i) and the water droplets carried in the air are intercepted by the water trap (j) and returned to the water tank (g). Summary of the Invention
[0006] To overcome the shortcomings of traditional evaporative condensers, the present invention provides a secondary pre-cooling evaporative condenser with a larger heat exchange area, higher heat exchange efficiency, and no scaling under the same volume. The objectives of the present invention are achieved through the following technical solutions: A horizontal shell and tube heat exchanger is connected in series between the precooler coil and the condenser coil of the traditional precooling evaporative condenser, and the condenser coil is replaced with an enhanced heat transfer tube, while the other structures remain unchanged. This results in a new type of evaporative condenser - the secondary precooling evaporative condenser. Its structure is shown in the attached figure. Figure 2 and attached Figure 3 .
[0007] The specific technical solution involves connecting a shell-and-tube heat exchanger in series between the precooler coil and the condenser coil of a conventional precooling evaporative condenser. The condensing coil in the conventional evaporative condenser is replaced with an enhanced heat exchange tube, while the other structural elements remain unchanged. The shell-side air inlet of the shell-and-tube heat exchanger is connected to the precooler's air outlet, while the shell-side air outlet is connected to the condenser's air inlet. The tube-side liquid inlet of the shell-and-tube heat exchanger is connected to the condenser's liquid outlet, while the tube-side air outlet is connected to the precooler's air inlet. The heat source fluid enters the precooler from the precooler air inlet and exchanges heat with the air outside the precooler tubes. After the temperature drops to approximately 60°C, it is discharged from the precooler outlet. This is the first cooling process. It then enters the shell side of the shell and tube heat exchanger from the shell side air inlet, exchanges heat with the heat sink fluid in the tube side, and after the temperature drops to approximately 45°C, it is discharged from the shell side air outlet and enters the condenser. This is the second cooling process. After entering the condenser, it exchanges heat with the cooling water and air outside the tubes, condenses into liquid, and then exits the condenser, completing the cooling and condensing process. After the condensed liquid heat source fluid is discharged from the condenser outlet, most of it enters the process system, while a small portion enters the tube side of the shell and tube heat exchanger, becoming the heat sink fluid in the shell and tube heat exchanger, exchanging heat with the heat source fluid outside the tube side. After phase conversion to gas, it is discharged from the shell and tube heat exchanger and enters the precooler from the precooler air inlet to participate in the next cooling and condensing process.
[0008] Because the heat source fluid entering the condenser is relatively low (around 45°C), not exceeding the scaling temperature of water (above 50°C), scaling of the cooling water circulating outside the condenser tubes is not a concern, allowing the condenser to maintain a high heat transfer coefficient. Therefore, the heat exchange coils in traditional evaporative condensers can be replaced with enhanced heat exchange tubes instead of plain tubes. Compared to plain tubes, enhanced heat exchange tubes of the same volume significantly increase the heat transfer area and enhance heat transfer efficiency. Consequently, for the same heat transfer capacity, the condenser coil volume can be significantly reduced, reducing metal consumption.
[0009] Since there is no scaling problem for the heat source fluid and heat sink fluid of the shell and tube heat exchanger, the heat exchange tubes of the shell and tube heat exchanger are also made of enhanced heat exchange tubes, which greatly enhances the heat transfer efficiency of the shell and tube heat exchanger and reduces the volume of the shell and tube heat exchanger.
[0010] The working principle of this secondary pre-cooling evaporative condenser is: The heat source fluid gas in a high-temperature superheated state enters the precooler (2) from the precooler air inlet (5), exchanges heat with the air outside the precooler (2) tube, releases heat and cools down to about 60°C, and then the heat source fluid is discharged from the precooler air outlet (6) of the precooler (2), completing the first cooling; then it enters the shell side of the shell and tube heat exchanger (3) from the shell side air inlet (7) of the shell and tube heat exchanger, exchanges heat with the heat sink fluid in the tube side, and is discharged from the shell side air outlet (8) of the shell and tube heat exchanger after the temperature drops to about 45°C, completing the second cooling; then it enters the condenser (4) from the condenser air inlet (9), and in the condenser (4), the heat source fluid exchanges heat with the cooling water and air outside the tube, and changes phase into a liquid at saturation temperature, and then is discharged from the condenser (4) from the condenser liquid outlet (10), completing the cooling and condensing process.
[0011] The heat sink fluid inlet (16) of the shell and tube heat exchanger is connected to the liquid outlet (10) of the condenser, and the heat sink fluid outlet (17) of the shell and tube heat exchanger is connected to the air inlet (5) of the precooler. After the heat source fluid condensed into liquid is discharged from the liquid outlet (10) of the condenser, most of it enters the process system, and a small part enters the tube side of the shell and tube heat exchanger (3), becomes the heat sink fluid of the shell and tube heat exchanger (3), and exchanges heat with the heat source fluid outside the tube side. After the phase is changed into gas, it is discharged from the shell and tube heat exchanger (3) and enters the precooler (2) from the air inlet (5) of the precooler to participate in the next cooling and condensing process.
[0012] The inlet of the water pump (11) is connected to the water tank (12). The water pump (11) draws cooling water from the water tank (12) and sends it to the sprayer (13). The sprayer (13) sprays the water onto the coil of the condenser (4). A small portion of the water absorbs the heat released by the heat source fluid and changes into water vapor and is drawn away by the fan (14). The air mixed with the water vapor passes through the precooler (2) and exchanges heat with the heat source fluid in the precooler (2) pipe and is discharged out of the precooler by the fan (14); most of the unevaporated water flows back to the water tank (12), and the water vapor and water droplets entrained in the air are intercepted by the water catcher (15) and returned to the water tank (12).
[0013] A liquid level controller (18) is provided before the heat sink fluid inlet (16) of the shell and tube heat exchanger to control the liquid level in the tube path of the shell and tube heat exchanger (3).
[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The use of a secondary cooling process greatly reduces the temperature of the heat source fluid before it enters the condenser (around 45°C), solving the problem of cooling water scaling caused by high heat exchange temperature; 2. Due to the reason in 1 above, the condenser heat exchange coil can be made of enhanced heat exchange tubes, which greatly increases the heat transfer area and enhances the heat transfer efficiency under the same volume. Therefore, under the condition of the same heat exchange capacity, the volume of the heat exchange coil can be significantly reduced, the metal consumption can be reduced, and the product production cost and product operation cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Attachment Figure 1 It is the structure diagram of pre-cooling evaporative condenser Figure 1 Among them: (a) precooler inlet, (b) condensing coil, (c) precooler outlet, (d) condenser, (e) condenser liquid outlet, (f) water pump, (g) water tank, (h) sprinkler, (i) fan, and (j) water catcher.
[0016] Attachment Figure 2 This is the main view (partial cross-section) of the secondary pre-cooling evaporative condenser structure. Attachment Figure 3 This is the side view of the secondary pre-cooling evaporative condenser structure Figure 2 、 3 Among them, (1) precooling type evaporative condenser, (2) precooler, (3) shell and tube heat exchanger, (4) condenser, (5) precooler air inlet, (6) precooler air outlet, (7) shell and tube heat exchanger shell side air inlet, (8) shell and tube heat exchanger shell side air outlet, (9) condenser air inlet, (10) condenser liquid outlet, (11) water pump, (12) water tank, (13) sprayer, (14) fan, (15) water collector, (16) shell and tube heat exchanger heat sink fluid inlet, (17) shell and tube heat exchanger heat sink fluid outlet, (18) liquid level controller.
[0017] The following is combined with Figure 2 , Attachment Figure 3 Explain the structure of the secondary pre-cooling evaporative condenser: The structure of the secondary pre-cooling evaporative condenser is the same as that of the conventional pre-cooling evaporative condenser. The fan (14) of the secondary pre-cooling evaporative condenser is arranged at the top, and the pre-cooler (2), the water trap (15), the sprayer (13), the condenser (4), and the water tank (12) are arranged downward in sequence from the fan (14); a shell and tube heat exchanger (3) is connected in series between the pre-cooler air outlet (6) and the condenser air inlet (9), and the shell and tube heat exchanger (3) is arranged between the condenser air inlet (9) and the condenser liquid outlet (1) of the pre-cooling evaporative condenser (1). 0) end, is set below a height of 1.5 meters below the condenser liquid outlet (10); a water pump (11) is set next to the water tank (12), the water inlet of the water pump (11) is connected to the water tank (12), and the water outlet is connected to the sprinkler (13); the shell and tube heat exchanger heat sink fluid inlet (16) is connected to the condenser liquid outlet (10), and the shell and tube heat exchanger heat sink fluid outlet (17) is connected to the precooler air inlet (5); a liquid level controller (18) is set in front of the shell and tube heat exchanger heat sink fluid inlet (16). DETAILED DESCRIPTION
[0018] The following is combined with Figure 2 , Attachment Figure 3 The present invention is described in detail with reference to the following embodiments: This embodiment uses the secondary pre-cooling evaporative condenser used in the ammonia refrigeration system as an example to describe the working process. Its design working conditions are: Calculated outdoor dry bulb temperature for summer ventilation: 34°C; The average outdoor wet-bulb temperature in summer is not guaranteed for 50 hours per year: 27°C; Calculated relative humidity for outdoor ventilation in summer: 64%; Refrigeration system condensing temperature: 35°C; Heat source fluid (refrigeration system refrigerant): ammonia; Heat sink fluid: ammonia.
[0019] The high-temperature superheated ammonia vapor from the refrigeration system enters the precooler (2) from the precooler air inlet (5), exchanges heat with the air outside the precooler (2) tube, releases heat and the temperature decreases. When the temperature drops to about 60°C, the refrigerant ammonia vapor is discharged from the precooler air outlet (6) of the precooler (2), and then enters the shell side of the shell and tube heat exchanger (3) from the shell side air inlet (7) of the shell and tube heat exchanger, exchanges heat with the ammonia liquid in the tube side. After the temperature drops to about 45°C, it is discharged from the shell side air outlet (8) of the shell and tube heat exchanger and enters the condenser (4) from the condenser air inlet (9). In the condenser (4), the refrigerant ammonia vapor exchanges heat with the cooling water and air outside the tube, and becomes a saturated liquid at the condensation temperature (35°C). Most of the ammonia liquid is discharged from the condenser (4) through the condenser liquid outlet (10), completing a condensation process, and then enters the refrigeration system. A small amount of ammonia liquid enters the tube side of the shell and tube heat exchanger (3) through the shell and tube heat exchanger heat sink fluid inlet (16), exchanges heat with the heat source fluid ammonia outside the tube side, and after phase conversion into gas, it is discharged from the shell and tube heat exchanger (3) and enters the precooler (2) through the precooler air inlet (5) to participate in the next condensation process. The liquid level controller (18) ensures that the ammonia liquid level in the tube side of the shell and tube heat exchanger (3) is stable at the required position.
[0020] The water pump (11) draws cooling water from the water tank (12) and sends it to the sprayer (13). The sprayer (13) sprays the water onto the coils of the condenser (4). A small amount of water absorbs the heat released by the heat source fluid and then changes into water vapor, which is then drawn away by the fan (14). The air mixed with the water vapor passes through the precooler (2) and exchanges heat with the refrigerant ammonia vapor in the precooler tube before being discharged from the device. Most of the unevaporated water flows back to the water tank (12). The water vapor and water droplets carried in the air are intercepted by the water trap (15) and returned to the water tank (12).
[0021] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features therein according to the disclosed technical content without creative labor, and these substitutions and modifications are all within the protection scope of the present invention.
Claims
1. A secondary pre-cooling evaporative condenser, mainly comprising a pre-cooling evaporative condenser (1) and a shell and tube heat exchanger (3), characterized in that: The shell-side air inlet (7) of the shell-and-tube heat exchanger is connected to the air outlet (6) of the precooler, the shell-side air outlet (8) of the shell-and-tube heat exchanger is connected to the air inlet (9) of the condenser, the heat sink fluid inlet (16) of the shell-and-tube heat exchanger is connected to the liquid outlet (10) of the condenser, the heat sink fluid outlet (17) of the shell-and-tube heat exchanger is connected to the air inlet (5) of the precooler, and a liquid level controller (18) is provided in front of the heat sink fluid inlet (16) of the shell-and-tube heat exchanger.