PARTICULAR HEAT EXCHANGE AREA

The subject of the invention is the shape of the heat exchange area of the heating plate of the plate heat exchanger.

Plate heat exchangers consists of heating plates laid alternately. Due to the way of their construction, one can differentiate the disassembled (screwed, gasketed) heat exchangers, not disassembled heat exchangers (soldered, welded, shell-plate), and partly disassembled heat exchangers (semi-welded gasketed). The essence of the construction of disassembled plate heat exchangers is the pressure of dis ountable heating plate package using the construction of frame and screws. Heating plates with a corrugated pattern contact each other by the tops of the notches are and guarantee tightness and creating channels, in which the working medium flows.

Gasketed heat exchangers work best in situations in which the logarithmic temperature difference is low, and thus the transferred heat load of the system is higher with increased flow rate of working media. Periodic operations related to the maintenance of plate heat exchangers include cleaning. In the case of a dismountable construction, this is done by disassembling the frame and removing dirt from the heating plates.

Brazed plate heat exchangers have heating plate packages that are permanently brazed together. They can be brazed with copper (common solution), nickel or stainless material to ensure adequate anti-corrosiveness in an aggressive work environment. In the manufacturing of semi-welded plate heat exchangers, the method of joining plates deserves particular attention. They are welded in pairs, then sealed with gaskets. One of the working media flows through the channels formed by the heating plates, then the cooling fluid or the cooled fluid flows between the pairs of such plates. In the case of a shell-plate exchanger, the plate package is located in the shell.

The entire heat exchange process in plate heat exchangers takes place on the walls of the channels formed by properly pressed and connected heating plate packages. During assembly of heating plates package, each subsequent heating plate is rotated by 180°. Such positioning and screwing, soldering, gluing or welding allows to create independent channels by means of which the heating and cooling medium will be able to participate in the heat exchange process. The shape of the heat exchange area of the heating plate of the plate heat exchanger has a strong influence on the heat exchanger work parameters. In addition to the heat exchange coefficient values, the important feature that characterizes each heat exchanger is the pressure drop. To determine the flow pressure drop, the pressure value at the exchanger input and the outlet are measured. The difference in the values obtained defines the flow pressure drop. In the case of heating plates with a corrugated pattern of high chevron angle geometry, the flow pressure drop is higher and the thermal efficiency is higher, while using lower chevron angle results in lower flow pressure drop, but also in decreased heat exchange.

Flow in plate heat exchangers can be single-pass or multi-pass. It refers to the number of passes of the working medium through the thermal length of the heating plate. In the case of multi-pass plate heat exchangers, the medium returns inside the heat exchanger, so that it flows along the thermal length of the heating plate many times.

The main advantages of plate heat exchangers include efficiency of heat exchange, compact design, small fluid volume, reliability and safety during work, flexibility of heat exchanger selection based on operating parameters, relatively low price in relation to the real efficiency of the device, relatively high turbulence of the working medium inside heat exchangers.

In order to increase the efficiency of plate heat exchangers, the heat exchange area of the heating plate is optimized. Modifications are made to its geometry, the shape of the heat exchange area is optimized and modified. The main assumptions of such steps include the optimal shape of the heat exchange area (while maintaining compact dimensions), the optimal increase in flow turbulence, minimizing the places where the flow of the working medium is laminar, maintaining or reducing pressure drops while increasing thermal efficiency and achieving local fluid turbulence that will ensure variable speed of the medium in the heat exchanger, thus ensuring a self cleaning process.

Heating plates of plate heat exchangers having on their surface corrugation pattern in the form of arms of the angle of a polygonal curve, which corrugations run parallel to each other, are known. Such heating plates have been disclosed, e.g. in the following patent documents - No. P.380994, EP 1094291 , EP 2394129 and WO 2007009615.

The purpose of the invention is to develop a surface design for heat exchange area of a plate heat exchanger which would provide increased thermal efficiency, with an optimum increase in the flow of the working medium inside the heat exchanger, would minimize the laminar flow structure of the working medium in the boundary and distribution areas.

The heat exchange area of the heating plate of the plate heat exchanger, the shape of which is corrugated, according to the invention, is characterized by the feature that the corrugations have additional local corrugations on their front and/or side surfaces forming notches and the apex line of the corrugations is discontinuous, in particular a polygonal line or a wavy line.

The additional local corrugations are characterized by the following parameters:

- the opening angle between the axis along which the top of the apex line of the corrugation is drawn and the axis parallel to the top of the apex line of the corrugation has a value from 90° to 179°;

- one of the acute angles of the triangle formed by the points of intersection of the top of the apex line of the corrugation with the axis along which the top of the apex line of the corrugation is drawn and the point furthest from the axis along which the apex line of the corrugation is drawn, and at the same time lying on the apex line of the corrugation has a value from 1 ° to 89°;

- the number of points furthest from the axis along which the apex line of the corrugation is drawn, and at the same time lying on the apex line of the corrugation is at least 2 for every 200 mm of the length of the axis along which the apex line of the corrugation is drawn;

- the distance between the points farthest from each other, and at the same time lying on opposite sides of the axis along which the apex line of the corrugation is drawn has a value in the range from 1 to 2000% of the value of the base of the isosceles triangle, whose sides form, in section (1 -1 ), the lines along which the lateral surface of the corrugation is drawn; - the angle of inclination of the lateral corrugation surface has a value from 1 ° to 89°;

- the radius of rounding the top of the corrugation has a value from 0.1 mm to 1000 mm.

The apex line of the corrugations is preferably in the form of a wavy line, the angle between the axis along which the apex line of the corrugation is drawn and the straight line intersecting the point furthest from the axis along which the apex line of the corrugation is drawn, and at the same time lying on the apex line, and the point of intersection of this line with the axis along which the apex line of the corrugation is drawn, is the opening angle.

The apex line of the corrugations is preferably in the form of a polygonal curve, the angle between the axis along which the apex line of the corrugation is drawn and the axis parallel to the apex line of the corrugation, is the opening angle.

Applying additional local corrugations for standard corrugations and/or forming the apex line of corrugation in the shape of a polygonal curve and/or a wavy line is intended to create local fluid turbulence, break the boundary layer of the fluid, local increase in fluid velocity. The above phenomena locally intensify the heat exchange, which in turn leads to an increase in thermal performance of the heat exchanger containing a package of heating plates with such a shape of the heat exchange area by at least 10%. A heat exchanger equipped with heating plates according to the invention is also less susceptible to surface contamination, which increases the intervals between its cleaning. The use of additional corrugations also affects the increase in pressure and cyclic loading resistance by increasing the stiffness of the heating plates and by compensating local stresses created during the work of the heat exchanger. The result is increased heat exchanger life.

The object of the invention is illustrated in the drawing, in which fig. 1 shows a heating plate of a plate heat exchanger in a front view with detail referring to the corrugations system and marking the zones through which the operating medium flows, fig. 2 - corrugation arrangement with reference to the face of the plate, fig. 3 and fig. 4 - corrugation arrangement with respect to the side surface of the heating plate corrugations, and fig. 5 - a view of an exemplary heat exchanger using heating plates having a heat exchange area shaped according to the invention. The heating plate (1) has areas on its surface through which the working medium flows: the port area (2), the working medium distribution area (3) and the effective heat exchange area (4). The effective heat exchange area (4) has a surface, the shape of which is corrugated (fig. 2) and is characterized by the feature that the corrugations have additional local corrugations (4S, 4F) on their side surface, and the apex line (4L) of the corrugations is shaped in the form of a polygonal curve. The additional corrugations have the following parameters: the opening angle (4a) between the axis along which the top of the apex line (4L) of the corrugation is drawn and the axis parallel to the top of the apex line (4L) of the corrugation has a value of 150°; one of the acute angles (4y) of the triangle formed by the points of intersection of the top of the apex line (4L) of the corrugation with the axis along which the top of the apex line (4L) of the corrugation is drawn and the point (4a) furthest from the axis along which the apex line (4L) of the corrugation is drawn, and at the same time lying on the apex line (4L) of the corrugation has a value of 30°; the number of points (4a) furthest from the axis along which the apex line of the corrugation (4L) is drawn, and at the same time lying on the apex line (4L) of the corrugation is 50 for every 200 mm of the length of the axis along which the apex line (4L) of the corrugation is drawn; the distance (4b) between the points (4a) farthest from each other, and at the same time lying on opposite sides of the axis along which the apex line (4L) of the corrugation is drawn has a value of 3mm; the angle of inclination (4o) of the lateral corrugation surface has a value of 60°; the radius of rounding (4d) the top of the corrugation has a value of 5 mm.

The heating plate (1 ) is part of a alternately laid heating plates package (6) being part of a plate heat exchanger (5). In addition, the heat exchanger (5) may have cover plates (7) and nozzles (8) used for mounting and connecting heat exchanger (5) elements. The elements of the heat exchanger (5), in particular the heating plates (1 ), are made of stainless steel, but can also be made of titanium, its alloys or of various metals and/or metal alloys and/or non-metals and/or plastics and or composite materials. Connecting the components of the heat exchanger (5) is done through the soldering process, but it can also be done by welding or gluing, or by screwing. This provides a wide range of applications in the industry, including energy, pharmaceutical, food, petrochemical, chemical, mining, at pool installations, HVAC, HVACR and sewage treatment plants.