Coaxial air to air heat exchanger for circumferential window frame installation   

Abstract: The circumferential and coaxial heat exchanger, consisting of frame, ducts for supplied and discharged air, as well as fans, is characterized in that, it is made up of at least one internal diaphragm (1), situated coaxially with the external enclosure (2) and separating at least two tightly divided coaxial ducts (3) and (4) for the supplied and discharged air. The internal diaphragm (1), separating the air ducts (3) and (4) is made of material combining high thermal conductivity, resistance to corrosion and adequate strength parameters (preferably aluminium alloys), and the shape of its cross-section is corresponding to the to the shape of external enclosure (2).

This is the National Stage of International Application PCT/PL2010/00033, with an international filing date of Apr. 30, 2010, which claims priority to Polish patent application P.390218, filed on Jan. 18, 2010.

FIELD OF THE INVENTION

The invention relates to a circumferential and coaxial heat exchanger, in particular used for the stabilization of required temperature level in heated and/or cooled accommodations.

BACKGROUND OF THE INVENTION

In the known solutions, the necessary heat energy within the heated accommodations is provided by four basic groups of the heat sources: located in the accommodations water, gas and electric radiators, stoves and fireplaces, air conditioners with additional heating function, as well as the air heated outside of accommodation and supplied by suitable ducts; systems making up the accommodation equipment, e.g. radio and TV equipment, cookers, irons, lighting, water heaters, etc.; humans and animals present in the accommodation, solar radiation, mainly penetrating through the windows.

In the case of air-conditioned accommodations, the air is cooled (conditioned) by cooling of the air in basically two types of air-conditioners: in the recent solutions, by air conditioners, cooling the air that is present in the accommodation (practically working in closed air cycle), in the older solutions, by air-conditioners, cooling the air supplied from the outside of accommodation.

In both solutions, in order to maintain the given temperature level in accommodation, the heating and cooling equipment is using the energy from the outside of the operated system. With the growth in the temperature difference between the accommodation and surroundings, the energy consumption becomes higher, which results from the thermodynamics principle, saying about equalization of energy levels. In the case of accommodations, such a process proceeds intrinsically, by the heat energy transmission through the walls, floors, ceilings and through the windows or doors (significance of this way depends on the level of thermal insulation of these elements), the heat energy emission mainly through the transparent elements (e.g. window panels), and also to some extent in a forced way, by replacing of heated/cooled air in the accommodation, for the “fresh” air from surroundings, through open or half-open windows, all kinds of leakages (so called unsealing of windows), gravitational ventilating ducts, mechanical machinery forcing-in or pumping out air from the accommodation (e.g. air intake/exhaust systems, fans, or certain types of air-conditioners).

As the specific solution, are so called systems of supply-exhaust ventilation with heat recuperation, consisting in making use of the so called heat exchangers of air-to-air type, in the existing ventilation systems.

From the Polish Utility Model No 60658, known is a solution of heat exchanger working in the forced system of mechanical supply-exhaust ventilation, where the medium participating in the heat exchange is a warm air carried away from the accommodation, and cold air drawn-in from the outside. The flow of air carried away from the accommodation takes place through thin-walled, flexible air pipes, built-in within the heat-insulating jacket-type enclosure. Drawn-in from outside cold air is supplied to the heat exchanger through the intake air connector pipe. Exchange of heat between the two media takes place through the lateral surface of flexible air pipes, within the whole volume of heat-insulating enclosure. Heated in the heat exchanger intake air, drawn-in from the outside, is carried away by outlet air connector pipe to the ventilation system installed in the accommodations. Whilst the cooled air, supplied from the accommodation by inlet collecting pipe, after passing through the heat exchanger is carried away by outlet collecting pipe through air pipes to the outside.

Among the disadvantages of such solution one can mention: necessity of introducing of additional system within the building, which requires servicing and maintenance, significant decrease in efficiency in the case of necessity of using longer air ducts, troublesome installation of necessary air pipes in new buildings, and often a lack of possibility of their installation in the existing buildings, difficult regulation of the system, and maintaining of assigned parameters of air in the individual accommodations, troublesome operation and maintaining of the safe level of system hygiene.

Another solution of the air-to-air type heat exchanger is a system of convection ventilation in a form of recuperator, located in the window frame, or glass doors, known from the German Patent Description DE 3802583. In this solution, the ducts supplying the air are situated in parallel with regard to each other, whereas the openings for air inlet and outlet are situated side-by-side in the upper part of frame. The air flow can be additionally assisted by the fans, situated on the outside part of frame, whilst the whole heat exchanger is reinforced by a special section.

This system is characterized by low output, which is due to the fact, that the length of the heat exchanging part of ducts is limited mainly to the vertical part of window or doors frame. The horizontal elements of frame are used as the location of air inlets and outlets, as well as that for the fans.

The low output of discussed system is affected by mutual location of the ducts, which is significantly reducing the surface of heat exchange. Another disadvantage is close location of the air inlet and outlet ports, resulting in a partial mixing up of the drawn-in and blown out air streams. Also the metal section, that is stiffening the window frame serves as an external enclosure of heat exchanger portion only, and is not actively involved in a desirable exchange of heat.

There are known also air-to-air heat exchangers, as described in the Patent Application EP1640552 or Utility Model Application DE 8337249, however in both solutions the air supply and outlet ducts are also situated side-by-side and in parallel with relation to each other, adhering one to another by one wall only, which also has a worsening effect on the low output of the whole system.

SUMMARY

The circumferential and coaxial heat exchanger according to the invention, consisting of frame, ducts for supplied and discharged air, as well as fans, is characterized in that, it is made up of at least one internal diaphragm, situated coaxially with the external enclosure and separating at least two tightly divided coaxial ducts for the supplied and discharged air.

It is preferable, that the internal diaphragm, separating the air ducts is made of material combining high thermal conductivity, resistance to corrosion and adequate strength parameters (preferably aluminium alloys), and the shape of its cross-section is corresponding to the to the shape of external enclosure, taking into consideration necessity of ensuring the tightness, maximization of the thermal conduction surface, as well as longitudinal and transverse rigidity of the diaphragm, as well as minimization of its thickness, taking into consideration the efficiency of thermal conduction.

In the case of employing in the heat exchanger, of more than one external diaphragm, it is preferable, that the two newly created ducts are alternately serving the air supplied to, and discharged from the accommodation.

Advantages of the heat exchanger, according to the invention include: co-axial air ducts, which ensure long air-flow path, as well as utilization of 90% of the ducts surface, serving as the active surface of heat exchanger, owing to which it is possible to obtain high thermal efficiency of the system, at the same time it is quite easy to obtain more than 1 sq. m. of active surface per 1 running meter of window frame with standard dimensions, whilst maintaining the air-flow resistance at low level. stiffening function of the diaphragm along with fins, owing to which, the use of additional reinforcing elements becomes not necessary, possibility of installation as a structural component of stationary and movable parts in the existing, as well as in planned window openings and door-ways and window walls, maintaining at the same time their basic functions, without necessity of their essential modification, simple assembly and control of working parameters, as well as maintenance taking into account the economic aspects, and at the same time maintaining high aesthetic virtues, that are accepted by the users.

Furthermore, the use of a heat exchanger, being the subject of this invention, allows also for significantly improved insulation of the accommodation from external noises, as compared with hitherto employed solutions, e.g. by elimination of used so far unsealing systems of windows for ventilation purposes, and also for reduction of energy costs and attending the system, thanks to the elimination of some structural and functional elements that have been used hitherto, such as e.g. a complex unsealing-and-half-opening furniture, necessity of window opening—the frame-casement unit, vertical and horizontal ventilation ducts in the building, or diminishing of the size of the heating-and-air-conditioning installation.

The subject of invention is explained on the embodiment, as shown on the drawing, where FIG. 1 shows vertical section of heat exchanger; FIG. 2 shows the heat exchanger section drawn along the line A-A as marked in FIG. 1; FIG. 3 shows the exchanger fragment section, drawn along the line C-C as marked in FIG. 1; FIG. 4 shows the exchanger fragment section drawn along the line Z-Z as marked in FIG. 1; FIG. 5 shows the perspective view of the exchanger fragment section, drawn along the line P-P as marked in FIG. 1; while FIG. 6 shows the transverse section of air ducts in the embodiment employing more than one internal diaphragm.

The internal diaphragm 1, situated coaxially with the external enclosure 2, is separating two tightly divided coaxial ducts 3 and 4 for the supplied and discharged air, whilst the internal diaphragm 1 is separating transverse surfaces of the internal sections of ducts 3 supplying air for the accommodation to the transverse surfaces of ducts 4 discharging air from the accommodation, in a ratio of 1:1.

Surface of the internal diaphragm 1 is smooth, or has at least one-sided longitudinal grooves or steps.

The internal diaphragm 1 is fitted with the four, integrated with its external surface longitudinal fins 5, which are serving for the stabilization of internal diaphragm 1 in the external enclosure 2, at the same time increasing rigidity of the whole heat exchanger, and also increasing the surface of heat exchange.

Situated in the section of external enclosure 2, holes 6, 7. 8, 9, which are ending with the relevant air ducts, and are supplying and discharging the air to/from heat exchanger, are arranged in relation to the accommodation, on the external (from the side of accommodation) as well as on the external (outside of accommodation) side of heat exchanger, whilst the holes 6 and 9 are situated on the internal side of heat exchanger, on the other hand, the holes 7 and 8 are arranged on the external side of exchanger.

In each duct 3 and 4, which is used for the supplied and discharged air in each direction of air flow, there is a fan 10, used for forcing the air circulation in this duct.

Surface of the internal diaphragm 1 can be smooth, or when it is justified, is fitted with one-sided or two-sided longitudinal grooves or steps. Such solution allows also for maintaining the rigidity of internal diaphragm 1, which is essential, considering its function of stiffening the exchanger rigidity, and at the same time reducing its thickness (weight), and increasing the thermal conduction surface, which allows to increase the heat exchanger thermal efficiency.

In the preferable embodiment, the internal diaphragm 1, creates the separation of transverse surfaces of the internal sections of ducts 3 supplying air to the accommodation, to the transverse surfaces of ducts 4 discharging air from the accommodation, in a ratio of 1:1. The tolerance of this ratio can amount up to ±30%, taking into account the specific condition of employing the exchanger, e.g. differential pressure between the accommodation and surroundings, occurring winds, and other methods of air exchange, as employed in the accommodation serviced.

The section of external enclosure 2 profiles can be of any geometrical shape, advantageously corresponding to the standard contours of shapes used in a typical—window and door sections (e.g. rectangle, square, hexagon, circle, oval), taking into consideration the possibility of window panels door leaves fixing and/or replacement, as well as necessary window furniture. This can be made of any material, ensuring proper mechanical properties (rigidity), resistance to the weather conditions (heat, light, humidity), and appropriate level of thermal insulation (thermal conductivity and leak-tightness). Preferable is the use of wood and its derivatives, plastics, composite materials, metals and their appropriate combinations.

Control of air-flow in the ducts 3 and 4, is in principle effected by the control of the appropriate fans 10: done manually by the user, or on the basis of automatic readings of the relevant sensors (temperature, air velocity, humidity, chemical analysis of the air, mechanical impurities), by means of switches controlled by the programmable microprocessor with possibility of setting by the user of his preferences for each heat exchanger and/or a group of heat exchangers, for each window opening/door-way, and/or for the whole accommodation, and/or for the whole building.

There is possibility of the following embodiments of air-flow control in the ducts 3 and 4, to be effected by means of fan 10: switch on/off the fan 10 for each air duct 3 and 4, switch on/off the fan 10 for each air duct 3 and 4, with the possibility of selecting a direction of air flow in the ducts, switch on/off the fan 10 for each air duct 3 and 4, with the possibility of adjusting the intensity of air flow in the ducts, switch on/off the fan 10 for each air duct 3 and 4, with the possibility of adjusting the intensity, and selection of a direction of air flow in the ducts.

In the case of employing more than one internal diaphragm 1, shown in the embodiment presented in FIG. 6 as diaphragms 1a, 1b, and 1c, created this way air ducts are serving alternately the air supplied to, and air discharged from the accommodation, where the ducts 3a and 3b serve for supplied air, whereas the ducts 4a and 4b serve for discharged air.

Solution according to the invention, obviously is not restricted to the described above embodiments only, but can be modified quite freely within the scope of patent claims.

Depending on the local conditions, in which the heat exchanger is used, fans can be adopted for operation in one direction only (higher fan efficiency at lower flexibility in controlling the heat exchanger), or else in two directions (lower fan efficiency and higher flexibility in controlling the heat exchanger).

Arrangement of two holes should take into consideration the specific conditions of heat exchanger operation, such as e.g. distribution of temperature within the accommodation and outside, at the same time it should ensure to the highest extent, the counter-current flow of supplied and discharged air to and from the accommodation, considering the possibility of taking advantage of higher efficiency offered by counter-current heat exchangers, and also should minimize the possibility of mixing up of the supplied and discharged air to/from the accommodation.

In the case of modular employment of more than one heat exchanger, operating in the in-series arrangement, the relevant holes should be located on the walls of exchanger, by which the mutually cooperating exchangers adhere one to another.

For the window opening or door-way in the wall of accommodation, the heat exchanger can be used in various combinations in every segment, and can be located in both external part (window/door frame), as well as in the internal part (movable door leaf/casement). In the case of using the heat exchangers in the external and internal part, each heat exchanger can operate independently, or by appropriate connection of air ducts, the heat exchangers can also operate as one exchanger with lengthened path of heat exchange.

Any combination of segments, resulting from operating needs of the accommodation, can be applied for each window opening/door-way.

The heat exchanger can be easily supplemented by filters regulating the chemical constitution of air, eliminating the allergenic or mechanical impurities.