Air-cooled oil-cooled dual combination condenser with high efficiency heat exchange and heat exchange control method thereof

Abstract

The application relates to a wind-cooled oil-cooled double-combination condenser with high heat exchange efficiency and a heat exchange control method thereof, which solves the defect of poor condenser heat exchange effect compared with the prior art. The bottom of the condenser body is provided with an electric heating assembly; the electric heating assembly comprises a refrigeration oil pipeline loop, the refrigeration oil pipeline loop is provided with an electric heating device, the refrigeration oil pipeline loop is arranged around the bottom of the condenser body, the inlet of the refrigeration oil pipeline loop is connected to A of a three-way joint, the outlet of the refrigeration oil pipeline loop is connected to B of the three-way joint, and an oil injection nozzle is arranged on C of the three-way joint. The application utilizes the unique structure of the condenser, combines the air flow characteristics and the U-tube inner vapor-liquid refrigerant characteristics, sets an independent refrigeration oil structure, reduces the space range, reduces the cost, increases the oil-cooled heat exchange mode in the weak heat exchange area of the air-cooled condenser, and realizes bidirectional heat exchange.

Description

Technical Field

[0001] This invention relates to the field of condenser technology, specifically to a dual-cooled (air-cooled and oil-cooled) condenser with high-efficiency heat exchange and its heat exchange control method. Background Technology

[0002] Currently, most air conditioning and refrigeration equipment on the market uses tube-fin condensers. The high-temperature and high-pressure refrigerant vapor at the compressor exhaust port enters the tube-fin condenser for condensation and liquefaction, releasing the refrigerant heat into the air to achieve the purpose of cooling.

[0003] Traditional tube-fin condensers use circular coils (with a circular radial cross-section) and fins (with circular perforations) fitted onto the coils to exchange heat between the medium inside the coils and the outside air, achieving heat dissipation. This is primarily achieved by the air carrying away heat as it passes over the fins. However, because traditional condensers use circular coils, on the air heat exchange side outside the coils, the air coming from the windward side passes through each coil, resulting in a large windward surface area and significant air resistance, requiring more power from the fan. Simultaneously, due to the large windward surface area of ​​the coils, vortices exist on the leeward side, creating dead zones where the air cannot reach. This severely affects the heat exchange effect on the air side outside the coils, resulting in low heat exchange efficiency. On the refrigerant heat exchange side inside the tube, because the refrigerant in a traditional single-inlet single-outlet condenser is undergoing a condensation phase change, the refrigerant is initially a gas when it enters the condenser. Gases have low density and high velocity, and are in a turbulent state. The heat exchange between the refrigerant and the inner wall of the heat exchange tube is strong and vigorous, resulting in a high heat transfer coefficient. After condensing through a portion of the heat exchange tube, a phase change occurs, gradually transforming the refrigerant into a liquid. The density increases, the velocity decreases, and it may even decrease to a laminar flow state. The heat exchange between the refrigerant and the heat exchange tube wall weakens, and the heat transfer coefficient gradually decreases.

[0004] In traditional single-inlet single-outlet condensers, the refrigerant undergoes a phase change inside the tubes, causing a gradual decrease in heat transfer coefficient, resulting in a low overall heat transfer coefficient. In terms of heat transfer outside the tubes, the air coming from the windward side passes through multiple rows of circular tubes, resulting in greater air resistance and requiring more power from the ventilation fan.

[0005] Therefore, traditional single-inlet, single-outlet cylindrical tube condensers suffer from high air resistance and low heat exchange efficiency. Multi-split outdoor unit condensers, employing air-cooled heat exchange, also exhibit relatively poor heat exchange performance due to the U-tube at the bottom of the finned copper tube heat exchanger being obstructed by the chassis folds and the airflow characteristics generated by the fan rotation. This results in a relatively simple and inefficient heat exchange method, reducing the overall energy efficiency of the air conditioner and hindering its overall energy efficiency improvement. Therefore, further improvements are necessary.

[0006] Furthermore, condensers, utilizing the principle of buoyancy, often employ a "bottom inlet, top outlet" design. In winter, frost can form on the condenser, especially at the bottom. Condensing units are used for refrigeration, and during this process, frost can form on the evaporator fins, affecting the unit's refrigeration efficiency. Therefore, defrosting the evaporator is necessary. Generally, condensing units use a timer to track compressor operation time. When a certain threshold is reached, the compressor cooling is disconnected, and the electric defrosting module is activated. After defrosting, the refrigerator returns to compressor cooling mode. However, existing defrosting methods cannot adjust based on the actual frost level on the evaporator fins; defrosting too early wastes energy, while defrosting too late affects refrigeration efficiency.

[0007] Existing defrosting technologies often involve periodic four-way valve reversing defrosting or exhaust diversion defrosting, which, from different perspectives, reduce the heat exchange capacity and energy efficiency ratio of air conditioners, hindering their efficient operation. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of poor heat exchange performance in existing condensers by providing a combined air-cooled and oil-cooled condenser with high-efficiency heat exchange and its heat exchange control method to solve the above problems.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A dual-cooled (air-cooled and oil-cooled) condenser with high-efficiency heat exchange includes a condenser body, an electric heating assembly installed at the bottom of the condenser body, and a refrigerant oil pipeline circuit with an electric heating device installed on it. The refrigerant oil pipeline circuit is arranged around the bottom of the condenser body, with its inlet connected to port A of a tee and its outlet connected to port B of the tee. An oil inlet is installed at port C of the tee.

[0011] A sensor is installed on the top cover of the condenser body, and the refrigerant oil pipeline loop is led from the bottom of the condenser body to the top of the condenser body and arranged in a circular pattern.

[0012] A heat exchange control method for a combined air-cooled and oil-cooled condenser with high-efficiency heat exchange includes the following steps:

[0013] Detect whether the condenser is currently in heating mode; if it is in cooling mode, turn off the electric heating element.

[0014] If in heating mode, the sensor monitors whether the outdoor temperature t0 ≤ 5℃; if not, the electric heating element is turned off.

[0015] If the outdoor temperature t0≤5℃, after the condenser unit has been running in heating mode for 30 minutes, the sensor will check whether the condenser unit has been frosted after a 5-minute interval.

[0016] If the condenser unit is frosted, turn on the electric heating element and calculate the amount of oil to be injected. Then, inject oil into the electric heating element and heat it according to the calculated amount of oil.

[0017] The calculation of the oil injection volume includes the following steps:

[0018] Let the current highest outdoor temperature be tmax, the maximum heat exchange capacity of the condenser be Q, and the highest discharge temperature of the compressor be t;

[0019] The heat exchange ratio of the bottom branch of the condenser is set as Q / n, where n is the number of branches of the condenser;

[0020] Determination of the overall heat transfer coefficient: In a closed space, the overall heat transfer coefficient c of the refrigeration oil structure on the bottom branch condenser was simulated and determined;

[0021] The oil injection volume M is set to be greater than 1 / 2 of the volume V of the refrigeration oil pipeline U, i.e., M≥1 / 8πd²L, and the oil injection volume M is less than 3 / 4 of the volume V of the refrigeration oil pipeline U, i.e., M≤3 / 16πd²L, where d is the inner diameter of the U-pipe and L is the length of the long U-pipe.

[0022] The formula for calculating the oil injection quantity M of the condenser is as follows:

[0023] M = (Q / n) / [c*(tmax-t)];

[0024] If the oil volume M < 1 / 2V, then charge according to 1 / 2V to ensure the reliable operation of the electric heating device;

[0025] If the oil filling volume M > 3 / 4V, then there should be at least two refrigerant oil lines, and the filling volume of each line should not be less than 1 / 2V.

[0026] The method for determining the overall heat transfer coefficient is as follows:

[0027] Fill the bottom refrigerant oil line and the upper U-tube of the condenser body with half refrigerant oil each;

[0028] In a closed laboratory, several thermocouples are evenly arranged at the bottom of the upper U-tube. The electric heating device is turned on. Within a specified time, based on the principle that the power consumption is approximately equal to the total heat absorption, the average temperature difference before and after is measured using thermocouples. The heat transfer coefficient c1 of the refrigeration oil structure to the bottom branch condenser is calculated in this way.

[0029] Increase the refrigeration oil to 3 / 4 of the volume V of pipe U, and calculate the overall heat transfer coefficient c2 of the refrigeration oil structure to the bottom branch condenser.

[0030] The intermediate value between c1 and c2 is taken as the comprehensive heat transfer coefficient c of the refrigeration oil structure to the bottom branch condenser.

[0031] Beneficial effects

[0032] This invention discloses a dual-mode air-cooled and oil-cooled condenser with high-efficiency heat exchange and its heat exchange control method. Compared with the prior art, it utilizes the unique structure of the condenser itself, combined with the air flow characteristics and the vapor-liquid refrigerant characteristics in the U-tube, to set up an independent refrigeration oil structure. This reduces the space required, lowers costs, and improves the heat exchange efficiency per unit volume by adding oil-cooled heat exchange to the weak heat exchange area of ​​the air-cooled condenser. This achieves bidirectional heat exchange, reduces space occupation, improves overall heat exchange uniformity, and solves the problem of not knowing when defrosting and frosting will occur. It can accurately perform defrosting and frosting, effectively saves energy, and effectively improves the cooling and heating efficiency, thereby achieving the purpose of enhancing heat exchange. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the present invention;

[0034] Figure 2 This is an exploded view of the structure of the present invention;

[0035] Figure 3 This is a top view of the structure of the present invention;

[0036] Among them, 1-oil injector, 2-te-way, 3-refrigeration oil pipeline circuit, 4-condenser body, 5-electric heating device, 6-sensor. Detailed Implementation

[0037] To provide a better understanding of the structural features and effects achieved by the present invention, a detailed description is provided below, accompanied by preferred embodiments and accompanying drawings:

[0038] like Figure 1 and Figure 2 As shown, the present invention provides a dual-combination air-cooled and oil-cooled condenser with high-efficiency heat exchange, comprising a condenser body 4.

[0039] An electric heating assembly is installed at the bottom of the condenser body 4. This assembly includes a refrigerant oil piping circuit 3 (a separate circuit that does not interfere with the refrigerant circuit). An electric heating device 5 is installed on the refrigerant oil piping circuit 3. The electric heating device 5 is activated as needed. When the condenser body 4 requires oil cooling circulation, the electric heating device 5 is not activated. When the condenser body 4 is defrosting (heat exchange), the electric heating device 5 can be activated. The electric heating device 5 is a conventional heating device, located anywhere on the refrigerant oil piping circuit 3. It forms an oil circuit for heat conduction through the loop transmission of refrigerant oil within the refrigerant oil piping circuit 3. The refrigerant oil piping circuit 3 is arranged around the bottom of the condenser body 4, typically in the lowest row, but not limited to the lowest row. The number of rows is not limited to two; multiple rows are also possible. The inlet of the refrigerant oil pipeline circuit 3 is connected to port A of the tee 2, and the outlet of the refrigerant oil pipeline circuit 3 is connected to port B of the tee 2. Ports A and B together form a circulation channel. An oil inlet 1 is installed on port C of the tee 2. The oil inlet 1 can be connected to an external pipe fitting or to an external source of refrigerant oil. In practical applications, the oil inlet 1 can utilize traditional technology to connect an external oil pump to achieve cooling oil circulation, or the condenser can be simply modified so that the condenser body 4 provides the power for the oil pump.

[0040] like Figure 3 As shown, a sensor 6 is installed on the top cover of the condenser body 4. The refrigerant oil pipeline circuit 3 is led from the bottom of the condenser body 4 to the top of the condenser body 4 and arranged in a three-dimensional arrangement around the condenser body 4.

[0041] Here, a heat exchange control method for a combined air-cooled and oil-cooled condenser with high-efficiency heat exchange is also provided, including the following steps:

[0042] The first step is to check if the condenser is currently in heating mode. If it is in cooling mode, the electric heating element will be turned off.

[0043] The second step is to monitor whether the outdoor temperature t0 is ≤ 5℃ using sensor 6; if not, the electric heating component will be turned off.

[0044] The third step is to check whether the condenser unit has frosted after the outdoor temperature t0 ≤ 5℃, and the condenser unit has been running in heating mode for 30 minutes, and then after a 5-minute interval, use sensor 6 to check whether the condenser unit has been frosted.

[0045] Fourth step: If the condenser unit is frosted, turn on the electric heating component and calculate the amount of oil to be injected. Then, inject oil into the electric heating component and heat it according to the calculated amount of oil.

[0046] The calculation of the oil injection volume includes the following steps:

[0047] (1) Let the current outdoor maximum temperature be tmax, the maximum heat exchange of the condenser be Q, and the maximum discharge temperature of the compressor be t.

[0048] (2) Set the heat exchange ratio of the bottom branch of the condenser to Q / n, where n is the number of branches of the condenser.

[0049] (3) Determination of the overall heat transfer coefficient: In a closed space, the overall heat transfer coefficient c of the refrigeration oil structure to the bottom branch condenser was simulated and determined.

[0050] The method for determining the overall heat transfer coefficient is as follows:

[0051] A1) First, based on the condenser body 4, fill half of the refrigeration oil pipeline at its bottom and half of the U-tube above it with refrigeration oil.

[0052] A2) In a closed laboratory, several thermocouples are evenly arranged at the bottom of the upper U-tube. The electric heating device 5 is turned on. Within a specified time, the average temperature difference before and after is measured using thermocouples based on the power consumption being approximately equal to the total heat absorbed. The heat transfer coefficient c1 of the refrigeration oil structure to the bottom branch condenser is then calculated.

[0053] A3) Increase the refrigeration oil to 3 / 4 of the volume V of pipe U, and calculate the overall heat transfer coefficient c2 of the refrigeration oil structure to the bottom branch condenser.

[0054] A4) Take the midpoint between c1 and c2 as the comprehensive heat transfer coefficient c of the refrigeration oil structure to the bottom branch condenser. It can be seen that the comprehensive heat transfer coefficient c is affected by different U-tube sizes, fin thicknesses, fin spacings, condenser shapes, etc.

[0055] (4) Set the oil injection volume M to be greater than 1 / 2 of the volume V of the U pipe of the refrigeration oil pipeline, i.e., M≥1 / 8πd²L, and the oil injection volume M is less than 3 / 4 of the volume V of the U pipe of the refrigeration oil pipeline, i.e., M≤3 / 16πd²L, to ensure a certain safe space for thermal expansion and contraction, where d is the inner diameter of the U pipe and L is the length of the long U pipe.

[0056] (5) Calculate the oil injection quantity M of the condenser. The calculation formula is as follows:

[0057] M = (Q / n) / [c*(tmax-t)];

[0058] If the oil volume M < 1 / 2V, then fill it with 1 / 2V to ensure the reliable operation of the electric heating device 5;

[0059] If the oil filling volume M > 3 / 4V, then there should be at least two refrigerant oil lines, and the filling volume of each line should not be less than 1 / 2V.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A heat exchange control method for a combined air-cooled and oil-cooled condenser with high-efficiency heat exchange, wherein the combined air-cooled and oil-cooled condenser includes a condenser body (4), an electric heating assembly is installed at the bottom of the condenser body (4); the electric heating assembly includes a refrigerant oil pipeline circuit (3), an electric heating device (5) is installed on the refrigerant oil pipeline circuit (3), the refrigerant oil pipeline circuit (3) is arranged around the bottom of the condenser body (4), the inlet of the refrigerant oil pipeline circuit (3) is connected to port A of a tee (2), the outlet of the refrigerant oil pipeline circuit (3) is connected to port B of the tee (2), and an oil inlet (1) is installed on port C of the tee (2); a sensor (6) is installed on the top cover of the condenser body (4), and the refrigerant oil pipeline circuit (3) is led from the bottom of the condenser body (4) to the top of the condenser body (4) and arranged around it; characterized in that, The heat exchange control method includes the following steps: 11) Check if the condenser is currently in heating mode. If it is in cooling mode, turn off the electric heating element. 12) If it is in heating mode, the sensor (6) will monitor and determine whether the outdoor temperature t0 ≤ 5℃; if not, the electric heating component will be turned off. 13) If the outdoor temperature t0≤5℃, after the condenser unit has been running in heating mode for 30 minutes, the sensor (6) is used to check whether the condenser unit has been frosted after a 5-minute interval. 14) If the condenser unit is frosted, turn on the electric heating element and calculate the amount of oil to be injected. Then, inject oil into the electric heating element according to the calculated amount of oil. The calculation of the oil injection volume includes the following steps: 141) Let the current highest outdoor temperature be tmax, the maximum heat exchange capacity of the condenser be Q, and the highest discharge temperature of the compressor be t; 142) Set the heat exchange ratio of the bottom branch of the condenser to Q / n, where n is the number of branches of the condenser; 143) Determination of the overall heat transfer coefficient: In a closed space, the overall heat transfer coefficient c of the refrigeration oil structure on the bottom branch condenser is simulated and determined; 144) Set the oil injection volume M to be greater than 1 / 2 of the volume V of the refrigeration oil pipeline U, i.e., M≥1 / 8πd²L, and the oil injection volume M to be less than 3 / 4 of the volume V of the refrigeration oil pipeline U, i.e., M≤3 / 16πd²L, where d is the inner diameter of the U pipe and L is the length of the long U pipe. 145) Calculate the oil injection quantity M of the condenser. The calculation formula is as follows: M = (Q / n) / [c*(tmax-t)]; If the oil volume M < 1 / 2V, then charge according to 1 / 2V to ensure the reliable operation of the electric heating device (5); If the oil filling volume M > 3 / 4V, then there should be at least two refrigerant oil lines, and the filling volume of each line should not be less than 1 / 2V.

2. The heat exchange control method for a combined air-cooled and oil-cooled condenser with high-efficiency heat exchange according to claim 1, characterized in that, The method for determining the overall heat transfer coefficient is as follows: 21) Based on the condenser body (4), fill half of the refrigeration oil into the bottom refrigeration oil pipeline and the U-tube above it; 22) In a closed laboratory, several thermocouples are evenly arranged at the bottom of the upper U-tube. The electric heating device (5) is turned on. Within a specified time, based on the principle that the power consumption is approximately equal to the total heat absorption, the average temperature difference before and after is measured using thermocouples. The heat transfer coefficient c1 of the refrigeration oil structure to the bottom branch condenser is calculated in this way. 23) Increase the amount of refrigeration oil to 3 / 4 of the volume V of pipe U, and calculate the overall heat transfer coefficient c2 of the refrigeration oil structure to the bottom branch condenser; 24) Take the value between c1 and c2 as the comprehensive heat transfer coefficient c of the refrigeration oil structure to the bottom branch condenser.

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