DE3135332A1 - PIPE HEAT EXCHANGER - Google Patents

Description

The invention relates and is particularly directed to heat exchangers on coaxial tube heat exchangers, as they are generally used in heat pumps, cooling unit circuits, air conditioning systems and the like.

The US-PS 31 99 583 describes a tubular heat exchanger for cryogenic systems. Efforts to improve such heat exchangers have been made to maximize shape changes the heat exchange performance by increasing the conductivity of the Exchange surfaces, the thermal gradient and the thermal insulation suitable surfaces. An optimization of the structure in this way requires too large, unnecessary amounts of expensive metals, whereby. the construction of complex multiple lines and distribution lines and the use of inserts is required that increase the risk of corrosion and blockage.

The invention is directed to providing a compact exchanger using the smallest amounts of metal in the return line for improvements in the heat exchange ratio.

The invention creates a heat exchanger for two flowing media ' with three thermally conductive tubes of different cross-sectional areas, which are nested in one another in heat exchange, so that an inner channel and an outer channel arise which together guide the first medium and delimit a central channel for the second medium. Inlet and outlet devices are in flow connection with the inner and outer channel and an inlet and outlet in flow communication provided with the middle channel. The middle channel can be surrounded by a tube that delimits the outer channel. The heat exchanger can be elongated with two ends, with the corresponding inlets and outlets for the two media near the ends are arranged and the heat exchange takes place in a single pass. follows. The cross-sectional areas of the inner channel and the outer channel and the locations of the inlets and outlets can be chosen so that approximately there are equal throughputs irv the two channels. The pipes - can have circular cross-section and the ratio of the diameter

is generally about 1.25: 1.5: 2. Preferably they are Tubes arranged coaxially. If the tubes have a curved part along their length, then the middle and outer. Channel each have spiral spacers, although good alignment even over 90 ° bends through a sand fill can be achieved before bending, as long as the mutual layers by fixing gas inlet and outlet pipes to the outer Pipe wall are kept exactly. Copper, copper-nickel and stainless steel are the metals of choice. The ratio of the through ^ meter is not always an optimum for heat exchangers at a given flow rate and in a given area and can therefore be higher or lower in some areas, where then these ratios also give good results.

It has been found that in household and commercial systems the Heat exchanger according to the invention an improvement in coaxial tube heat exchangers and it can be expected that the same improvement will be obtained as the size of the heat exchangers increases. For example, for municipal or municipal facilities may need the ratios of the pipes undergo a corresponding change in order to change the flow conditions of the media; however, the improvement is mainly due to the heat exchange performance, which relies on the liquid and gas contacting two curved cylindrical surfaces instead of just one. It is to be expected that Flow velocities of. 1.2 to 2.4 m / sec. with heat exchangers of this type for liquids with a specific heat of the order of magnitude those of water are useful.

An embodiment of a heat exchanger according to the invention is intended to. are explained in more detail with reference to the drawing. This shows in

1 shows a schematic section through a heat exchanger; Figure 2 is a section through one end of the heat exchanger;

Figure 3 is an external view of the same end for reproduction

the coupling of hose connections; and in

Fig. 4 'is a schematic view of the insert in a

Heat pump system used as a heat source or sink for a domestic swimming pool.

According to FIGS. 1 and 2, the heat exchanger consists of an inner one round tube 2 with an outside diameter of approx. 25 mm, an outer round tube 4 with an outside diameter of approx. 50 mm and a central one 'Round tube 6 with an outside diameter of about 38 mm. All three pipes are made of stainless steel (18 swg). For a device with 1.65 kW. (2.25 hp) the heat exchanger is 270 cm (9ft) long. A gas inlet conduit and a gas outlet conduit 10 extend through the outer tube. 4 through. The middle tube 2 has at each end a widened part 12 which is seated with a sliding fit in the middle tube 6, so that . by means of an annular weld seam 14, the two tubes 2 and 6 are formed a gas-tight passage channel 16 can be combined with one another. The inner channel 18 and the outer channel 20 carry water through the heat exchanger from water inlet 21 to water outlet 22. The middle passage ■ channel 16 is the condenser of the coolant circuit of the heat pump (see. Fig. 4). The water flows through the outer and inner channels 18, 20. In order to improve the heat exchange in the inner channel 18, a stainless steel coil 26 at the inlet to the inner channel used that creates an initial vortex that sustains remain. This spiral need only extend a short distance into the canal. The water flows thus divide at the water inlet 21 and reunite at water outlet 22.

The gas inlet and outlet connections are shown in more detail in FIGS. The outer tube 4 has a slot 28 with a semicircular blind end. The gas inlet line 10 meets the blind end of the slot and is held in place by the end 30 of a threaded sleeve 32 which is fixed to the outer tube 4 by a weld seam 34. The connection of the gas inlet line 10 to the outer tube 4 is .durch a fillet weld 36 sealed. The sleeve "32 takes a tube

coupling 38 on.

According to FIG. 4, a pump 40 circulates water from a swimming pool ¹ 42 through a filter 44 and the exchanger which forms part of a domestic heat pump 24. The heat pump 24 hall, a flow rate of approx. 2.1 m / sec through the exchanger upright, which is housed in a pipe loop in the heat pump housing. The heat exchanger only collects sensible heat from the pool water and in continuous operation there is an input / output ratio of. 1: 5 achievable in contrast to the best embodiments of known heat exchangers of comparable size, which only achieve 1: 3.

The relevant temperatures are as follows:

Gas inlet 82 "C Gas outlet 61 ¹¹ C Water inlet 10 ⁰ C Water outlet 60 "C

The heat exchanger according to the invention has the following advantages:

The heat exchanger only needs to be provided with minimal thermal insulation to become because the hot gas of a comparatively large volume flowing liquid is surrounded. The heat exchanger is cheap ■ in production and can be installed compactly in the existing system, with the two ends of the pipe coil connected by a pipe are, which has an outlet, so that the liquid of the heat exchanger can be emptied.

High flow velocities of the liquid can be achieved either by installing heat exchangers in parallel so that additional heat pump circuits can be included in the system, or by enlarging the pipe widths with a corresponding increase in the performance of the system.

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Claims (9)

Claims {]] Tube heat exchanger for the heat exchange between two flowing media, characterized by three tubes of thermally conductive material of different cross-sections, which are nested in one another in a heat exchange relationship to form a) an inner channel (1B) ₃ b) an outer channel (20), both for the first flowing medium c) a central channel (16) for the second medium and further characterized by d) an inlet (21) and an outlet (22) in flow communication with the inner (18) and the outer channel (20) and e) an inlet (8) and an outlet (10) in flow communication with the middle channel (16). 2. tubular heat exchanger according to claim .1 ,. characterized in that the central channel (16) is surrounded by the tube (6) which delimits the outer channel (20). 3. tubular heat exchanger according to claim 1, characterized g e k e η η • ζ β; i. c h η e t that the heat exchanger as elongated Body is designed with two ends and the inlets and outlets for the two media are arranged in the vicinity of the ends and the heat exchange done in a single pass. 4. tubular heat exchanger according to claim 3, characterized in that the cross-sectional areas of the inner channel (18) and the outer channel (20) and the locations of the inlet (21) and outlet, respectively (22) are chosen such that approximately the same flows are present in both channels (18, 20). 5. tubular heat exchanger according to claim 1, characterized in that the tubes (2, 4, 6) have a circular cross-section have and the ratio of the diameters of the order of 1.25: Ί.5: 2 lies. 6. Tube heat exchanger according to claim 1, characterized in that that the tubes (2, 4, 6) are arranged coaxially. 7. tubular heat exchanger according to claim 6, characterized in that the inner channel (18) a swirl of the through caused the channel flowing medium. 8. tubular heat exchanger according to claim 7, characterized in that g e k e η η - shows that the inner channel (18) has a spiral insert (26) has, which e-ine the medium flowing through the inner channel (18) helical direction of movement granted. 9. tubular heat exchanger according to claim 6, characterized geke η η - *. shows that the tubes (2, 4, 6) form a spiral with one another with a complete turn.