UA28868U - Heat exchange element with reduced capacity of working body - Google Patents

Abstract

A heat exchange element of heat-power or cooling complexes comprises a pipe finned by roll-screw method, made of aluminum or copper. Besides that to decrease capacity of working medium and to intensify the heat exchange to each pipe one places ejector rod.

Description

Description of the invention

The useful model is related to thermal power engineering and refrigeration technology. 2 The design of the heat exchange element will be in demand at energy and refrigeration facilities, where, in addition to high heat exchange efficiency, it is necessary to minimize the volume of the device for the heat of the refrigerant or refrigerant.

The need for a small volume of the system is dictated both by economic considerations and by the requirements of ecology and explosion and fire safety.

The use of heat exchange devices, which include low-capacity elements, is characterized by a high 70 intensity of heat exchange on both sides.

The external rib surfaces work intensively due to the lack of contact and thermal resistance between the rib and the pipe, which occurs in modern embedded plate or coiled ribs.

Thanks to the well-known rolling screw manufacturing technology, the rib is an extension of the pipe wall. In addition, the cross-section of the rib has a trapezoidal shape, which ensures uniform distribution of heat along its entire height. 12 The surfaces of the ribs are oriented relative to the air flow at some angle, depending on the step between the ribs, which ensures turbulence of the air flow and intensifies heat exchange.

The high intensity of heat exchange, with a reduction of more than 1.5 times the internal volume of the element, is achieved due to the placement of the rod-extruder inside the entire length of the pipe. As a result, a kind of spiral channel is formed in the pipe between the extruder and the spiral grooves on the pipe wall, which were formed during the rolling-screw ribbing technology.

The use of the proposed heat exchange elements provides a low-cost progressive, environmentally friendly manufacturing technology, as well as a high (higher than in analogues) heat exchange intensity with a minimum capacity in the heat exchange element of the working environment. Below are analogs and a prototype, the study of the features of which makes it possible to objectively assess the perfection of the proposed device. 29 IAS.S. ZU 1467363 AI. E28E13/12, 23.03.89. Bul. Mo111. in

The task is to intensify the heat exchange of the pipe.

The pipe consists of cylindrical elements that are separated by diaphragms with holes and contain spherical elements. Each element is placed in the corresponding element. The diameter of the holes in the diaphragms of the elements is smaller than the diameter of the ball, and the diameter of the ball is smaller than the internal diameter of the element. со 30 During the movement of the heat carrier, the ball hangs in the current at some distance from the hole and the heat carrier current (Ge) deviates approaching the surface of the walls of the cylindrical element, the wall layer of the heat carrier is turbulent, improving the intensity of heat exchange by 30-3595. The method of increasing the intensity of heat exchange is clear and simple, but the implementation is quite time-consuming and requires a complex technology. with

Each element is a separate product with exact geometry and strict sequence in manufacturing. In the process of operation, due to the constant change in hydraulic resistance, the first balls at the entrance will try to cover the holes in the diaphragm of the element, and at the end of the pipe - on the contrary, due to the slight movement of the carrier, the ball will descend to the lower element. The phenomenon will be observed, especially, during the movement of the viscous coolant when the pipe is placed vertically. The authors did not specify the material and mass characteristics of balls for "use in pipes with sharp and viscous coolant. From 70 IAS. 954787 G28E13/06, P28E1/10, P2807/00, 30.08.82. Bul. Moz21 s Device for twisting the coolant in a tubular heat exchanger.

From" The task is to improve manufacturability.

The task is achieved thanks to the swirler placed in each fossil pipe in the form of a snail.

The swirlers in the pipes are smoothly connected at the tangent, and the snail-shaped ones are equipped with a common cover. 45 The air stream enters the swirler, where it slowly swirls and moves in the pipe, rotating and moving along the pipe.

Ge | Unlike the known devices for twisting the heat carrier, where there are sharp edges at the entrance and it is necessary to make covers for each snail, the proposed technology ensures a smooth entrance to the snail of each pipe tube equipped with a common cover.

Gee! 20 Regarding the heat transfer intensity of the swirling air flow in the pipe, a doubt arises because due to the friction of the air flow against the walls of the pipe, the swirling current immediately breaks up and continues to move along the pipe in a chaotic, disorganized flow, which, by the way, creates favorable conditions for the turbulence of the boundary layer of the heat carrier.

The effect of the swirling current is manifested at a short distance from the exit of the auger, and then the air will move along the entire section of the pipe, depending on its diameter and length, chaotically, so the improved technology of coupling the auger with the pipe is not justified. with IAS With 1546826 AI, E28E19/00, 28.02.90. Bul. As).

Device for intensification of heat exchange.

The task is to intensify heat exchange and increase the operational reliability of the device.

The device consists of a system of plates hinged on rods, which are also mounted on 60 endless tape stretched on rollers.

The plates are L-shaped and attached to the rods at the bending point with the possibility of 909 rotation.

The device is equipped with a drive for rotation in a plane perpendicular to the heat exchange surface at 1802, which provides a change in the direction of movement of the tape with plates attached to it. The coolant enters through the inlet pipe and drives the plates, which occupy a vertical position in the upper part of the belt, where 69 plates free the heat exchange surface from contamination. The lower part of the belt with plates moves in the opposite direction. Here, the plates do not touch the heat exchange surface, but provide turbulation of the coolant. To clean the lower half of the surface, with the help of the drive, the direction of movement of the tape changes and the plates take a vertical position, similar to the previous one.

For reliable contact of the plates with the surface, they are made empty with spring-loaded inserts.

The design of the device is very complex, material-intensive and unreliable in operation, because the device is equipped with moving elements, complex detachable nodes that require constant supervision and adjustment.

In addition, the authors of the development do not provide an explanation regarding the configuration of the device: rectangular or round in cross-section. Based on the drawing, the configuration is rectangular, which does not allow the use of a 7/0 rotary mechanism. If round, then each plate must consist of two parts to pass each through the tension rods without the end band. The distance between the two halves of the plate should be greater than the diameter of the rod, and as a result, there will be strips in the upper and lower parts of the surface that are not freed from dirt, but on the contrary, layers of dirt will accumulate in these areas.

The efficiency of heat exchange is questionable, because only half/5 of the surface constantly participates in heat exchange, and the part where the plates "work" to clean the surface does not participate in heat exchange.

It is unlikely that the plates with the tape will move at all due to the difference in hydraulic resistance, for this it is necessary to organize a directed flow of the coolant only on the vertical plates, otherwise the resistance in the total volume of the pipe cavity will equalize and everything will stop.

IAS 5 1702152 AI, E28E13/18,13/14, 30.12.91. Bul. Mo48)

Heat exchange surface.

The task is to increase the heat transfer properties of the heat exchange surface.

A porous coating in the form of a wire spiral is applied to the metal fin heat exchange surface. The turns of the spiral on some part of the perimeter are deformed and bent inward by the convexity of the spiral. In addition, the bulges are placed with an angular displacement along the spiral. When the viscous coolant flows around the turns of the spiral, it twists and the heat exchange with the pipe wall intensifies, and when it flows around the inwardly bent parts of the spiral perimeter, the heat exchange intensifies between the inner and wall layers of the coolant flow. t

Thickening of the cross-section of the pipe not only along its perimeter, but also in the central part of the flow, leads to a significant increase in the hydraulic resistance to the movement of a viscous liquid. During the movement of the liquid, which washes a significant number of elements of the spiral, each of them forms a shadow zone, where the laminar boundary layer of the so-so liquid practically does not move, and the more such leaks, the more stagnant local zones that impair heat transfer. co

An increase in heat transfer in this situation can be achieved by increasing the speed of movement, as a result of which turbulent zones will appear, but this way is associated with large energy costs.

IAS 861922 P28E13/00, 09.07.81. Bul. Mo33) co

Turbulizer. with

The task is to intensify heat exchange.

In the heat exchange pipe, the turbulator is made in the form of a wire spiral. The coils of the spiral on some part of the perimeter are deformed and bent inwards by the convexity of the spiral, in addition, the convexities are placed with an angular displacement along the spiral. When flowing around the turns of the spiral, the viscous coolant is twisted and the heat exchange with the pipe wall intensifies, and when it flows around the inwardly bent parts of the perimeter of the spiral, the heat exchange with c intensifies between the inner and wall layers of the coolant flow. . Scattering of the cross-section of the pipe not only along its perimeter, but also in the central part of the flow, and? leads to a significant increase in the hydraulic resistance to the movement of a viscous liquid. During the movement of the liquid, which washes a significant number of elements of the spiral, each of them forms a shadow zone, where the laminar boundary layer of the liquid practically does not move, and the more such leaks, the more stagnant local zones, worsening

GI heat transfer.

Intensification of heat transfer in this situation can be achieved by increasing the speed of movement, as a result of which turbulent zones will be formed, but this way is associated with high energy consumption. o (Patent OA 26078 SI, P28R1/26, 30.04.99. Bul. Mo2

Heat exchanger.

Me. The task is to increase the efficiency of the heat exchanger by making it from relatively inexpensive components instead of pipes.

The heat exchanger contains a package of plates - outer ribs with rows of holes cut off along the perimeter, which enter the cavity of the adjacent plate with cut-off holes, as a result, internal passages are formed. Ribs made of corrugated tape are placed in the cavities of the internal passages.

The ribs are made in the form of discrete inserts and placed in the passages at a certain distance between them. c Inseparable connections of plates and tapes are formed by their compatible heat treatment to the melting temperature of copper.

Heat exchangers made of copper or aluminum contain external ribs - plates and internal ones made of tapes or corrugations, which form through straight or helical channels in the number of 7 to 37 pieces.

The technological process of manufacturing a heat exchanger is carried out in the following sequence: first, tapes with corrugations are collected into a set, which is then introduced into a set of plates connected by holes with flanges, after which heat treatment is carried out.

A significant difference of the useful model is that, in addition to the highly developed outer surface in the form of b5 flat plates, the presence of ribs in its internal passages over the entire cross-sectional area significantly increases the internal surface of the heat exchanger, through channels made of corrugated tapes, which are oriented along a helical line, significantly increase efficiency of the heat exchanger due to the turbulence of the passing heat carrier.

The use of low-value metal waste instead of pipes for the manufacture of heat exchange surfaces of the proposed technology is very attractive.

But the manufacturing technology itself and, especially, the connection of heat exchanger elements requires high-precision equipment, special stamping devices and high-temperature large-sized furnaces.

The reliability of the sealing of welded elements for heat exchangers of refrigerating plants, where there is a sharp fluctuation of temperatures from low negative to 1002C and above, as well as the high penetrating 7/0 property of precious freons, which leak through microscopic leaks, is a concern.

Analyzing the design features, manufacturing technology and operating conditions of the analogs in question, it turned out that a significant number of heat exchange elements and devices are complex and time-consuming to manufacture, and technological processes have a negative impact on the environment.

The high material consumption of individual devices does not justify the costs of their creation due to the low 7/5 efficiency that is expected.

Processes with heat treatment of heat exchange element assemblies, in addition to high specific energy consumption, create an increased level of danger in the technological process and worsen the environmental situation in production.

Attempts in some cases to increase the intensity of heat exchange inside the pipe elements by cluttering the live section with spiral turbulators or ribbon channels lead to significant specific energy consumption, and during long-term operation due to contamination, heat exchange is inevitably impaired.

It turns out to be the closest to the declared and what is used as a prototype.

Utility Model Patent OA 17579 Byul. Mo10, 16.10.2006br. E28E13/12; E2803/041|.

The heat exchange element of low-capacity highly efficient devices.

The task is to create a device that, at a high intensity of heat transfer, significantly reduces the volume of c) heat exchange devices for the refrigerant or coolant.

The heat exchange element includes heat exchange pipes, extrusion rods, spiral tapes and fixing spring clamps and spring clamps. with

The volume of the device, which includes a heat exchange element, is reduced due to placing in each pipe along its entire length a squeezer, concentrically located in the tape, which with its wool touches the inner walls of the pipe and the squeezer without tension. co

The material of the extruder is heat-resistant and inert to the working environment (graphite, its compositions, ceramics and polymer materials with closed pores, as well as metal hermetic thin-walled cylindrical sections). co

Spiral tape is made from any metal strip up to 1mm thick. The step between turns of the spiral Ha is 4-6 pipe diameters or the angle between the axis of the extruder and the vector of flow movement 7" "225-352, which ensures the movement of the flow along the spiral, and not along the trajectory of the screw, where "72455.

Fastening the ends of the tapes to graphite plastic or polymer extruders is carried out with spring clamps, and to metal ones - by soldering or welding.

The ratio of the diameter of the squeezer to the inner diameter of the pipe is within 0.6-0.8 (where 0.6 is for freons and the heat of the refrigerant and 0.8 for ammonia and carbon dioxide). and The presence of the squeezer and spiral tapes ensures a 1.5...2 times reduction of the internal volume, and "" also significantly increases the intensity of heat transfer.

This is achieved due to the organization of the flow in a spiral ring shape due to the intensive turbulization of the thin ring spiral flow, which washes the walls of the pipe, reducing the thermal resistance of the laminar co-wall layer. At the same time, the entire liquid volume of the annular flow takes part in the heat exchange. Despite the significant reduction in the capacity of the system, due to the placement of squeezers in the pipes, the presence of which in combination with spiral belts contributes to the intensification of heat exchange, all efforts for the perfection (ee) of the device are directed to solving only the internal problem. But there are many air-cooling devices at power engineering and refrigeration facilities, the Achilles' heel of which is inadequate heat exchange conditions from the outer surface. c Unfortunately, this issue was not paid attention to in the work.

The spiral channel formed between the smooth walls of the pipe and the spiral tapes fixed to the extrusion provides for the movement of a compact spiral current, which, under appropriate thermal loads, can lead to pulsations or noticeable hydraulic shocks, as a result of which the geometry of the tapes may be deformed and the system's operating cycle may be disturbed. c In the work, it is noted that the tapes are attached to the squeezer only at two ends, and the rest of the body of the spiral lies without tension on the squeezer. As a result, during the operation of the system, the environment during movement can cause resonant oscillations of the turns of the tape, which after some time can destroy the rods or 60 depressurize the thin-walled metal extrusion cylinders. And the technology of manufacturing spiral tapes, attaching them to squeezers and installing them in the pipes of the heat exchanger requires considerable time and manual effort.

The technical problem, the solution of which is aimed at the useful model, is that, in comparison with known devices and their manufacturing technologies, the proposed device, with a minimum system capacity for heat 65 coolant or refrigerant, would ensure the maximum efficiency of heat exchange, both internal and external surfaces

The solution to the problem is achieved by using and retrofitting the heat exchange surface of the element, manufactured according to advanced technology (rolled-screw method) with minimal specific energy consumption and high environmental cleanliness.

The heat exchange element, which is included in the cooling batteries of refrigerating chambers, air coolers of freezer chambers, heaters, air conditioners and air cooling condensers, consists of a finned tube, manufactured by the rolling-screw method, inside which a rod-extruder is mounted along its entire length. The material of the rod can be ceramics, polymer materials, graphite layer compositions, resistant to low (near minus 302) and high (near 120 2C) negative 7/0 temperatures, as well as to freon media, lubricants, and aqueous solutions of ethylene glycol or glycerin.

In contrast to known technological processes for the manufacture of heat exchange elements with developed external and internal surfaces, the proposed element has the following advantages.

Any surfaces with flat wound, planted or welded fins on pipes are characterized by low efficiency due to the formation of an air gap between the fin and the pipe, which creates a basic 7/5 thermal resistance. After chemical treatment, the device is immersed in molten metal (zinc or tin) to eliminate contact and thermal resistance. This procedure is expensive, time-consuming and environmentally harmful. It is also known that flat attachment ribs are easily covered by air and have low heat transfer, so corrugations, holes, protrusions, etc. are made on each rib.

A completely different picture is formed when using a heat exchange element from a pipe obtained by the rolling-screw method. In addition to the fast, highly efficient, environmentally friendly process of finning the pipe in the specified way, due to the deformation of the metal of the thick-walled pipe, the outer rib is a continuation of the wall.

That is, there is no contact resistance between the rib and the pipe. In comparison with lamellar ribs of the same thickness, the rib after rolling has a trapezoidal shape in section, which provides minimum thermal resistance along the height of the rib. The formation of the outer rib is accompanied by the formation of spiral grooves inside the pipe

The step between them is equal to the step between the outer ribs.

The spiral shape of the outer rib ensures the orientation of its surface at a certain angle to the air flow, c) the boundary laminar layer is turbulent. Known plate fins require separate turbulators.

Internal spiral grooves are also natural turbulizers when the medium moves. Even without any additional equipment, the indicated surface has the highest indicators of heat exchange efficiency, both externally and internally. with

By combining the high heat exchange efficiency of the element with its smaller capacity for refrigerant or coolant, we will obtain a heat exchange element that will have no analogues in terms of its efficiency. X,

The novelty of the useful model lies in the fact that an extruding rod is placed inside the pipe along its entire length, which, in addition to reducing the internal volume, creates turbulent flows during the movement of the medium. Turbulization occurs as a result of the movement in the spiral channel of the flow, which is formed between the squeezer and the co

Grooves in the pipe walls formed during rolling. with

Fig. 1 shows a heat exchange element with a pusher rod placed inside.

The diameter of the rod is 0.6 of the inner diameter of the pipe. The heat exchange element consists of a ribbed tube 1, made by the rolling-screw method, spiral ribs 2, spiral grooves 3, fasteners 4, and an extruding rod 5. The fasteners are tightly fitted to the rod, and their legs are oriented relative to the axis of the pipe under

Angle 3-52, which ensures flow turbulence. The distance between the fasteners is 10...15 inner diameters of the pipe, and the length of the legs is equal to the diameter of the fastener. The legs of the retainer in the pipe touch its walls without tension. The squeezer is fixed at both ends of the pipe with spring clamps 6. "» Fig. 2-4 shows the heat exchange apparatus, which includes the proposed elements. Fig. 2 shows the variants of refrigerating chamber batteries, air coolers, calorifiers and air cooling condensers. Fig. 3 heat exchanger device for any coolant and coolant vapor that condenses. Fig. 4 - air cooling condenser, calorifier.

Operation of the device.

Each of the above modifications of the devices (Fig. 2-4) has operational features. (oo) For example, during the boiling of freon in the battery or air cooler (Fig. 1, 2) with the lower supply of the liquid, the high intensity of heat exchange will be in the lower pipes due to the high speed of the vapor-liquid mixture b or wet steam formed during the boiling of the liquid. When the refrigerant is supplied from above, the liquid fills the spiral channels incompletely, therefore, almost along the path of the liquid, the vapor-liquid mixture will move quickly, of course, with a reduced intensity of heat transfer. During the movement of the coolant (Fig. 2, 3) due to the turbulence of the flow in the spiral slit channel with the participation of the guide legs of the retainers, the intensity of heat transfer will be observed along the entire path of its movement.

Phenomena observed in air cooling condensers and heaters (Fig. 3, 4). It is known that when superheated steam enters the intertube space of a shell-and-tube condenser, it does not cool down and condense for a long time due to its low speed, thereby increasing the pressure in the device. Better conditions when supplying steam to the pipes of evaporative and irrigation condensers, here, due to the limited space, the speed of steam is high 60 and the effect of cooling and condensation increases.

The proposed device is the most perfect and effective, in which when steam enters the slit channel formed between the squeezer, the spiral grooves and the guide legs of the retainers, it immediately acquires a high speed, and the steam flow acquires spiral rotations, as a result of which the steam quickly cools and condenses The presence of spiral grooves provides "unloading" of the main surface from the layer 65 of condensate, which forms thermal resistance. Here, all the condensate immediately fills the spiral grooves and is diverted to the receiver, thereby ensuring a high intensity of heat transfer during film condensation.

The use of a heat exchange element in the operating mode of the heater (heating of air with superheated steam or coolant without phase transformations) creates favorable conditions for the intensity of heat transfer due to the presence of grooves in the walls of the pipe, which, together with the squeezer, form a spiral channel that turbulates the flow.

Information confirming the feasibility of the proposed device.

The authors of the work conducted tests of aluminum evaporators and air cooling condensers, in which the heat exchange surface is made by the rolling-screw method. Condensers were researched in the laboratory of the Odesa Kholodmash plant, and evaporators manufactured at the Odesa Prodmash plant at the mechanical plant in Balashikha, Kursk region. (Russia), were tested in industrial conditions in the meat processing plants of Tiraspol (Moldova), Kalinkovichi (Belarus) and Nizhny Novgorod (Russia). In the tests, high results were obtained in the aspects of thermal energy and operation. The speed of meat freezing is almost doubled compared to traditional batteries with coiled steel ribs, and the rib surface was freed from the "snow coat" in no more than 15...20 minutes against 1...2 hours spent on getting rid of the same fur coat made of coiled steel ribbing.

Due to the possible destruction of aluminum elements by ammonia, the air coolers were made in a bimetallic version, an aluminum fin cover was put on the steel pipes by screw-rolling, and the freon air cooling condensers were made of aluminum grade 01 - without a steel pipe on a special mandrel.

Equipping elements made of aluminum pipes made by rolling-screw method with extruders is not 2o There is no doubt. Depending on the length and diameter of the pipes of the heat exchanger, squeezer rods with a diameter of 0.6 times the diameter of the pipe are selected.

Fasteners must be firmly fixed on the rods, with the legs deviated by 3-52 relative to the axis of the rod. At both ends of the pipe, the rods are fixed with spring clamps.

In the preparation of the tube of the device, the extruded ones are inserted and the device is assembled with the help of collectors or coils by soldering or welding. After assembly, the device is subject to a mandatory leak test. WITH

Claims (5)

The formula of the invention is 1. A heat exchange element of heat power or refrigeration complexes, which includes a pipe ribbed by the rolling-screw method, made of aluminum or copper, which is distinguished by the fact that in order to reduce the capacity of the working medium and intensify the heat exchange, a rod is placed in each pipe - squeezer co 2. Heat exchange element according to claim 1, which differs in that, for effective operation, the rod-extruder is axisymmetrically placed in the pipe freely on the legs of the retainer, located at an angle of 1202, and the retainers with З5 tightly sit on the extruder at a distance of 15-20 pipe diameters, itself the squeezer rod is fixed on two ends of the pipe with spring clamps. C. The heat exchange element according to claims 1, 2, which differs in that inside the pipe, the intensification of heat exchange is achieved due to the turbulence of the medium in the spiral channel between the walls of the extruder and the grooves in the walls of the pipe, formed in the process of rolling-screw technology. " 4. The heat exchange element according to claim 3, which differs in that the additional turbulence of the flow is carried out with the legs of the retainer, which are deviated relative to the axis of the rod by 3-52, and their length in the direction of movement is equal to the diameter of the extruder. and" 5. Heat exchange element according to claim 1, which differs in that, for reliability and durability, the material of the squeezer must be heat-resistant (ceramics, graphite and its compositions, polymer materials) and inert to Freons, their lubricants and aqueous solutions of ethylene glycol or glycerin. who would The heat exchange element according to claim 1, which differs in that to intensify the heat exchange from the side of the external fins, it is necessary to reduce the fin coefficient, that is, to increase the pitch between the fins, where the extremum of turbulence corresponds to the largest pitch, which forms the maximum angle between the flow vector and the surfaces of the fins. b 50 IR e) c 60 b5