DE8432762U1 - HEAT EXCHANGERS, ESPECIALLY FOR HEAT PUMPS AND REFRIGERATION SYSTEMS - Google Patents

Description

R & G SCHMÖLE METALLWERKE GMBH & CO KG, 5750 Menden

Heat exchangers, in particular for heat pumps and refrigeration systems

The invention relates to a wound heat exchanger according to the features in the preamble of claim 1.

Modern refrigeration technology requires the most powerful and compact possible Heat exchangers that work in all operating states of the heat transfer media consistently optimized heat transfer properties should have.

In already known heat exchangers of the type mentioned, so-called Coaxial condensers, the outer side of the inner tube is corresponding to the poorer heat transfer during condensation commercial refrigerant enlarged by ribbing. For example, outer-ribbed inner tubes are in one Integrated, helical circumferential ribs manufactured by the rolling process. The inner surface of these pipes through which in countercurrent the second liquid heat transfer medium, e.g. Water that is led is smooth due to the better heat transfer between the liquid and the inner wall of the pipe. Disadvantage of such Heat exchangers with finned tubes that are smooth on the inside is the greater dependence of the total heat transfer capacity on the flow rate of the liquid heat transfer medium in the Inner tube.

Proceeding from this, the invention is based on the object of providing heat exchangers of the type mentioned in such a way that an increase in heat transfer performance with acceptable material and manufacturing costs is achieved that is within the limits of an acceptable pressure loss for the liquid heat exchange medium carried in the inner tube is maintained over wide flow velocity ranges.

The object is achieved according to the invention in that the inner tube a finned tube with outer and inner helical ribs of different configuration, each molded onto the tube wall Is used; the outer ribs in a known embodiment as described in the prior art having an approximately triangular shape Have a cross-section with a low rib slope, but the additional inner ribs have an approximately trapezoidal cross-section greater slope.

Ribbed tubes with additional trapezoidal inner ribs with a large pitch are known from DE-P 24 31 162, but not theirs Use in wound heat exchangers of the type mentioned.

To achieve good heat transfer properties, it is advisable to arrange 6 to 24 trapezoidal, helically circumferential inner ribs evenly distributed over the circumference, with a rib pitch (t) of 40 to 80 mm per 36G ^J rib circumference; where preferably the rib foot width (f) 1.4 to 1.6 mm, the rib head width (k) 0.4 to 0.8 mm and the rib height (h) 0.3 to 0.7 mm, measured in a direction perpendicular to the pipe axis standing level, should be.

In a known manner, one or more of these finned tubes with spacers are introduced into a jacket tube and wound into a Coiled heat exchanger with a preferably circular or flat oval base. The ends of the jacket pipe and the Inner pipe or the inner pipes are made by fittings or special armatures connected, which ensure a uniform flow distribution of the heat exchange media.

A heat exchanger designed according to the invention with guidance of the Refrigerant in the shell space and the second heat transfer medium to this in countercurrent in the interior of the finned tubes has the advantage that in comparison to the known double tube systems in use As a refrigerant condenser, a considerable increase in performance with acceptable pressure losses is possible without the material and To increase manufacturing costs accordingly. In particular, the increase in performance at lower flow velocities of the im The interior of the finned tubes meaning flowing heat exchange medium, whereby the heat exchanger designed according to the invention is preferred for use in refrigeration systems and heat pumps that are designed for strongly changing performance areas.

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The following is a preferred embodiment of one according to the invention trained heat exchanger with reference to the associated Drawings described.

In the drawing show:

Fig. 1 shows a heat exchanger with an internally and externally ribbed Inner tube in cross section

FIG. 2 schematically shows a longitudinal section through the heat exchanger according to FIG. 1

3 shows a heat exchanger deformed to form a helix, in a side view

4 shows a heat exchanger deformed into a helix in a plan view

Fig. 5 graphical representation of the measurement results with a device according to the invention Capacitor.

The heat exchanger according to FIGS. 1 to 4 consists of a jacket tube (1), in which an inner tube (2) designed as a ribbed tube is arranged coaxially.

According to FIG. 4, fittings (3) for the inlet and outlet of a refrigerant, for example Frlgen, provided while a heat-absorbing medium, e.g. B. water, in the countercurrent principle in that led through the fittings, at the ends (4) the inner tube (2.) which is not finned on the outside, is supplied or discharged.

The helically circumferential ones formed on the outside of the inner tube (2) Ribs (5) with an approximately triangular cross-section and with a low rib slope are shown in FIGS.

In addition, the inside of the Inner tube (2) helically encircling, trapezoidal inner ribs (6) formed. In Fig. 2, for example, the course is a these inner ribs (6) shown over a rib circumference of 180 °, where the dimension t / 2 is half of the rib pitch (t) per 360 ° rib rotation.

In Fig. 1, dimension (f) denotes the width of the rib foot, dimension (k) the rib head width and the dimension (h) the rib height.

Example:

A heat exchanger deformed into a coil (number of turns: 7j5) with a jacket pipe made of copper 35 x 1> 5 mm and a Inside and outside ribbed inner tube made. The dimensions of the inner tube were:

Core tube outer diameter 16.0 mm

Inner tube diameter 14.5 mm

Rib height outside 1.5 mm

External rib division 1.0 mm

Inner rib foot width 1.5 mm

Rib head width inside 0.7 mm

Inner rib height 0.6 mm

Rib pitch 42.5 mm / rev

Number of inner ribs 10

With the flow of water in the inner tube with an inlet ^{temperature of 35 °} C. and of refrigerant R 22 with a condensation temperature of 45 ^° C. in the jacket space, those shown in FIG. 5 by curve (7) were reproduced when the heat exchanger was used as a countercurrent condenser in a heat pump Heat transfer performance measured as a function of the flow velocity of the water in the inner pipe.

The curve (8) gives the same dependency for a previously common heat exchanger of the same size, but with the inside smooth inner tube, again.

The person skilled in the art easily recognizes the through the use of the ef according to the invention Heat exchanger achieved higher performance, which - also recognizable by the different slopes of the Curves - drops less sharply at lower flow velocities.

Claims (5)

- 2 claims . ^ Coiled heat exchangers, in particular for the condensation of refrigerants in heat pumps or refrigeration systems, consisting of a jacket tube (1), of at least one finned tube (2) arranged therein with helically encircling ribs (5, 6) formed on its inside and outside. , and end fittings (3) each with an opening for a refrigerant to flow through in the space between the jacket tube (1) and inner tube (2) and each with an * 'opening for a second heat transfer medium to flow through the inner tube (2)
• ^ characterized by that the inner ribs (6) of the inner tube (7) with a rib cross-section constant trapezoidal shape and a greater slope than that of the outer ribs (5). 2. Heat exchanger according to claim 1, characterized in that the Inner rib inclination (t) of the inner tube (2) per rib circumference of 360 ° is 40 to 80 mm. 3 · Heat exchanger according to claim 1 and 2, characterized in that that 6 to 24 evenly distributed on the circumference inner ribs (6) are provided. 4. Heat exchanger according to claim 1 to 3, characterized in that that measured in a plane perpendicular to the pipe axis for the inner ribs (6) the rib foot width (f) 1.4 to 1.6 mm, the The rib head width (k) is 0.4 to 0.8 mm and the rib height (h) is 0.3 to 0.7 mm. 5. Heat exchanger according to claim 1 to 5> characterized in that that the jacket tube (1) with one or more internal finned tubes (2) in a known manner to form a wound heat exchanger is shaped with a circular or flat-oval base.