WO2019025636A1

WO2019025636A1 - Heat transfer unit, heating unit and heating apparatus for recreational vehicles, and recreational vehicles

Info

Publication number: WO2019025636A1
Application number: PCT/EP2018/071300
Authority: WO
Inventors: Vito BOTTICELLA; Enrico Paci; Marco ZANI
Original assignee: Dometic Sweden AB
Current assignee: Dometic Sweden AB
Priority date: 2017-08-04
Filing date: 2018-08-06
Publication date: 2019-02-07
Anticipated expiration: 2020-02-04
Also published as: WO2019025633A1; DE112018003288T5; DE212018000249U1; WO2019025635A1; DE112018003284T5; DE212018000248U1; WO2019025634A1; CN213237518U; CN213237945U

Abstract

The present invention refers to a heat transfer unit (6A) for transferring heat from a heated gas to a liquid in particular to water, wherein the heat transfer unit in particular is for a heating apparatus (1) for a recreational vehicle. The heat transfer unit (6A) comprises a gas conduit (60A) configured to receive and transfer the heated gas and a heat transfer tank (504A) configured to contain the liquid. The gas conduit (60A) has a gas inlet (603A), a gas outlet (604A) as well as a first heat transfer zone (601A) surrounded by a corresponding chamber and a second heat transfer zone (602A) surrounded by a corresponding gas pipe. The chamber surrounding the first heat transfer zone (601A) is coupled to the gas inlet (603A), the gas pipe surrounding the second heat transfer zone (602A) is coupled to the chamber surrounding the first heat transfer zone (601A) and the gas outlet (604A) is coupled to the gas pipe surrounding the second heat transfer zone (602A). The gas conduit (60A) is geometrically shaped in such a way that due to convection, heated gas entering the gas conduit (60A) at the gas inlet (603A) at first has to flow through the first heat transfer zone (601A) and then through the second heat transfer zone (602A) before it can leave the gas conduit (60A) through the gas outlet (604A). The chamber surrounding the first heat transfer zone (601A) and the gas pipe surrounding the second heat transfer zone (602A) are provided within the heat transfer tank (504A). The chamber surrounding the first heat transfer zone (601A) is provided as triangular chamber and the gas pipe surrounding the second heat transfer zone (602A) is coupled to the triangular chamber surrounding the first heat transfer zone (601A) in the area of one of its corners. Moreover, the present invention refers to a heating unit, a heating apparatus and a recreational vehicle provided with such a heat transfer unit.

Description

Heat transfer unit, heating unit and heating apparatus

for recreational vehicles, and recreational vehicles

This invention relates to a heat transfer unit and a heating unit as well as a heating apparatus with such a heat transfer unit, and recreational vehicles equipped with one of the above devices.

A heat transfer unit for transferring heat from a heated gas to a liquid in particular water, usually comprises a gas conduit configured to receive and to transfer the heated gas for example from a burner, and a heat transfer tank configured to contain the liquid to be heated.

In known heat transfer units, often moisture from the heated gas condenses in the gas conduit and causes problems like clogging or oxidizing the walls defining the gas conduit. In addition thereto, the condensed and conglomerated water could move towards a burner and cause there malfunctions for example by extinguishing the combustion flames.

Accordingly, the scope of the present invention is to provide a heat transfer unit having high efficiency with regard to the heat transfer from the heated gas to the liquid to be heated while being quite long-lived and reliable. Moreover, the scope of the present invention is to provide corresponding heating units, heating apparatus and recreational vehicles utilizing the concept developed from this task.

These scopes are achieved by the heat transfer units according to claim 1 , a heating unit according to claim 5, a heating apparatus according to claim 8 as well as a recreational vehicle according to claim 10.

One aspect of the present invention refers to a heat transfer unit for transferring heat from a heated gas to a liquid. Such a heat transfer unit in particular is provided for a heating apparatus for a recreational vehicle. According to the present invention, the heat transfer unit comprises a gas conduit configured to receive and to transfer the heated gas and a heat transfer tank configured to contain the fluid to be heated. The gas conduit has a gas inlet, a gas outlet as well as a first heat transfer zone surrounded by a corresponding chamber and a second heat transfer zone surrounded by a corresponding gas pipe. The chamber surrounding the first heat transfer zone is coupled to the gas inlet, the gas pipe surrounding the second heat transfer zone is coupled to the chamber surrounding first heat transfer zone and the gas outlet is coupled to the gas pipe surrounding the second heat transfer zone. The gas conduit is geometrically shaped in such a way that due to convection, heated gas entering the gas conduit at the gas inlet at first has to flow through the first heat transfer zone and then through the second heat transfer zone before it can leave the gas conduit through the gas outlet. The chamber surrounding the first heat transfer zone and the gas pipe surrounding the second heat transfer zone are provided within the heat transfer tank of the heat exchanger. The chamber surrounding the first heat transfer zone is provided as triangular chamber and the gas pipe surrounding the second heat transfer zone is coupled to the triangular chamber surrounding the first heat transfer zone in the area of one of its corners

This results in a very reliable and highly effective heat transfer unit due to the fact that on the one hand, by the triangular shape of the chamber the generation of turbulences in the gas flow is suppressed and on the other hand, there are virtually no dead-rooms in which moisture can condense out of the gas and conglomerate. Thus, negative effects merging with condensed and conglomerated moisture within the heat transfer unit like oxidation effects or clogging of the flow path of the heated gas can be avoided.

Preferably, the triangular chamber surrounding the first heat transfer zone has a triangular bottom surface, a triangular top surface and three in particular rectangular side surfaces connecting the triangular bottom surface to the triangular top surface at the three sides of the two triangular surfaces. A gas inlet is provided along a first side surface of the triangular chamber and the gas pipe surrounding the second heat exchange zone is coupled to the opposite end of the triangular chamber. In particular the gas pipe surrounding the second heat transfer zone is coupled to the top surface of the triangular chamber near the location, where the second side surface and the third side surface touch each other.

This results in a highly efficient shape with regard to a mostly unhindered gas flow and a huge area for the heat transfer.

Preferably, the triangular chamber surrounding the first heat transfer zone is arranged horizontal within the heat transfer tank. Alternatively, the triangular chamber is arranged ascending from the first side surface of the triangular chamber to the location, where the gas pipe surrounding the second heat transfer zone is coupled to the triangular chamber within the heat transfer tank.

This allows for improving the flow characteristics of the heat transfer unit further, as the effect of convection driving the heated gas through the gas conduit is enhanced.

Preferably, the triangular chamber surrounding the first heat transfer zone is formed of two identical components, which are fixed together mirrored against each other to form the triangular chamber.

This allows for a simple and cheap production of the triangular chamber and thus of the whole heat transfer unit. Another aspect of the present invention refers to a heating unit for heating liquid and in particular water, wherein the heating unit in particular is provided for a heating apparatus of a recreational vehicle. The heating unit according to the present invention comprises at least one of the above described heat transfer units and a burner coupled to the heat transfer unit. The burner comprises at least one burner module and a combustion chamber with an igniter. The burner module has a conduit with an inlet port for receiving a mixture of primary air and combustible gas, and an outlet port leading to the combustion chamber. The outlet port in particular is a line of nozzles and the conduit in particular is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. The combustion chamber is coupled to the gas inlet of the gas conduit of the heat transfer unit. Alternatively, the combustion chamber of the burner is provided at least partially as section of the triangular chamber surrounding the first heat transfer zone.

This concrete configuration allows transferring the advantageous effects of the above described heat transfer unit to a heating unit. Providing the outlet port as a line of nozzles improves the distribution of the mixture of primary air and combustible gas within the combustion chamber and thus the completeness of the combustion. The utilization of the Venturi effect for supplying the mixture of primary air and combustible gas to the combustion chamber allows omitting further devices fulfilling this task. This results in reduced costs for the heating unit and a decreased susceptibility to errors. Providing the combustion chamber at least partially or even providing the whole burner within the triangular chamber surrounding the first heat transfer zone allows saving installation space and thus reduces the overall size of the heating unit. In addition thereto, heat not only is transferred from the heated gas (the combustion gas) within the first heat transfer zone liquid within the heat transfer tank but also heat is transferred from the combustion flames to the walls of the triangular chamber surrounding the first heat transfer zone and thus to the liquid within the heat transfer tank.

Preferably, the burner comprises a passage configured to guide a flow of secondary air into the combustion chamber. In particular a fan configured for forcing the flow of secondary air into the combustion chamber is provided within the passage.

This allows for providing more air to the combustion zone than can be achieved via the conduit. Moreover, when providing the fan, the amount of the further provided air can be controlled and if desired, air pressure can be applied to the heated gas within the combustion chamber and the gas conduit of the heat exchanger to increase the flow rate and to set the temperature of the heated gas by controlling the amount of secondary air. This results in further possibilities to operate the heating unit according to the user's requirements.

A further aspect of the present invention refers to a heating apparatus for a recreational vehicle. The heating apparatus according to the present invention comprises at least one of the above described heating units or a heating unit having a first burner and at least one of the above described heat transfer units coupled thereto. The heating apparatus further has an inlet for supplying the first heating unit with air and an exhaust gas pipe for discharging exhaust gases form the heating apparatus.

This allows for transferring the advantageous effects of the above described heating units and/ or of the above described heat transfer units to a heating apparatus for recreational vehicles.

Preferably, the heating apparatus further comprises an additional heating unit having a burner and a heat exchanger coupled to the additional burner. The additional heating unit is connected in parallel with the already provided heating unit to the inlet and the exhaust gas pipe of the heating apparatus.

This configuration allows improving the performance capability of the overall heating apparatus and to heat various fluids mostly independently from each other with only one compact heating apparatus. In particular, when one of the provided heating units is configured to heat gases and the other heating unit is provided for heating fluids, a very versatile heating apparatus is achieved.

Preferably, the two provided heating units of the heating apparatus are arranged side by side or one above the other within the heating apparatus.

This allows for a highly symmetrical and very space-saving overall shape of the provided heating apparatus. A final aspect of the present invention refers to a recreational vehicle, wherein the recreational vehicle according to the present invention comprises at least one of the above described heating apparatus, at least one of the above described heating units and/ or at least one of the above described heat exchangers.

This configuration allows transferring the advantageous effect of the above described heating apparatus, heating units and/ or heat transfer units to a recreational vehicle.

These and other features of the invention will become more apparent from the following detailed description of a preferred, non-limiting example embodiment of the present invention, with reference to the accompanying drawings, in which:

Fig. 1 illustrates a schematic functional scheme of an exemplary embodiment of the heating apparatus according to the present invention;

Fig. 2 illustrates a spatial view of an exemplary heating apparatus according to the embodiment of the of Fig. 1 ; Figs. 3 to 6 illustrate various cross-sectional views of the heating apparatus of Fig. 2;

Fig. 7A and 7B illustrate spatial views of heating units of the heating apparatus of

Figs. 2 to 6.

With reference to the accompanying drawings, the numeral 1 denotes a heating apparatus, according to the present invention.

According to one exemplary embodiment of the present invention, illustrated schematically in Fig. 1 and in spatial views in Figs. 2 to 6, a heating apparatus 1 comprises a combustion unit with at least one burner and a combustion chamber 2. The burner has a burner module 3. The burner module 3 includes a conduit 301 with an inlet port 302 for receiving a mixture of primary air and combustible gas. The conduit 301 further has an outlet port 303, opened to the combustion chamber 2 to generate a flame within the combustion chamber 2.

Here, the outlet port 303 of the conduit 301 is a line of nozzles 15 configured to generate the flame. The heating apparatus 1 also includes an igniter 304 (see Figs. 3 to 5 and 7A), which is positioned in the combustion chamber 2.

The conduit 301 is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. In the illustrated configuration, the heating apparatus 1 further comprises a passage 4 (see Fig. 5) configured for provide a flow of secondary into the combustion chamber 2.

The heating apparatus 1 includes a duct 5, for conveying a fluid to be heated. The fluid to be healed can for example be a gas like breathable air.

The duct 5 has an inlet 501 and an outlet 502 (see Figs. 3 to 5). Here, the duct 5 includes a fluid pump 503. The fluid pump 503 is configured to force the fluid flowing through the duct 5.

Here, the fluid pump 503 is configured to aspire the air from the recreational vehicle within which the illustrated heating apparatus can be provided, and to force it into the duct 5 from the inlet 501 to the outlet 502. In an alternative embodiment, the fluid pump 503 is configured to aspire air from an external environment and to force it entering into the duct 5. The duct 5 includes a grid, positioned in front of the fluid pump 503 to avoid a pollution of the duct 5. In the illustrated configuration, the fluid pump 503 is an air pump. However, the fluid pump 503 also can be a liquid pump. The inlet 501 of the duct 5 further includes a filter to avoid pollution of the system. When provided in a recreational vehicle, commonly the outlet 502 of the duct 5 is opened to the inner of the recreational vehicle. The heating apparatus 1 includes a heat exchanger 6.

The heat exchanger 6 in the illustrated embodiment is configured for transferring heat from heated exhaust gases flowing from the combustion chamber 2 through a gas conduit 60 of the heat exchanger to the fluid flowing in the duct 5. As best may be seen in Fig. 5, the gas conduit 60 of the heat exchanger 6 has two heat exchange zones: a first heat exchange zone 601 surrounded by a corresponding gas pipe, configured for heat exchange between the heated exhaust gases, generated in the combustion zone 2, within the first heat exchange zone 601 and the heated exhaust gases within a second heat transfer zone 602, and the second heat exchange zone 602 surrounded by a corresponding chamber, configured for heat exchange between the heated exhaust gases and the fluid to be heated flowing through the duct 5. The combustion zone 2 can be provided at least partially as section of the first heat exchange zone 601 as it is the case in the illustrated embodiment. The gas conduit 60 further has a gas inlet 603 and a gas outlet 604. The gas pipe surrounding the first heat exchange zone 601 is coupled to the gas inlet 603, the second heat exchange zone 602 is connected to the first heat exchange zone 601 and the gas outlet 604 is coupled to the chamber surrounding the second heat exchange zone 602. The gas conduit 60 is geometrically shaped in such a way that heated exhaust gas entering the gas conduit 60 at the gas inlet 603 at first has to flow through the first heat exchange zone 601 and then through the second heat exchange zone 602 before it can leave the gas conduit 60 through the gas outlet 604.

The chamber surrounding the second heat exchange zone 602 and the gas pipe surrounding the first heat exchange zone 601 are provided within the duct 5 of the heat exchanger 6.

The gas pipe surrounding the first heat exchange zone 601 is arranged within the chamber surrounding the second heat exchange zone 602 and the gas inlet 603 is provided with respect to the longitudinal axis of the heat exchanger 6 radially within the gas outlet 604. This allows an improved heat exchange and a quite compact spatial structure of heat exchanger 6.

Here, the gas pipe surrounding the first heat exchange zone 601 has smooth walls, communicating with the second heat exchange zone 602. The second heat exchange zone 602 is conformed as a channel-like chamber whose walls include a plurality of lamellas. As illustrated here, the walls preferably include some lamellas pointing into the second heat exchange zone and/ or some lamellas pointing into the duct surrounding the gas conduit 60. Both groups of lamellas are configured to optimize the heat exchange between the exhaust gases flowing through the second heat exchange zone and fluid in particular the breathable air, flowing through the duct 5. Here, the heating apparatus 1 comprises a fan 7 configured for forcing the flow of secondary air through the passage 4.

In the illustrated embodiment, the heating apparatus 1 comprises a feeding chamber 8. The feeding chamber 8 is configured to receive air from the external environment. The fan 7 is provided within the passage 4 or like illustrated here at the inlet of the feeding chamber 8 to force air from the external environment into the feeding chamber.

The feeding chamber 8 is in fluid communication with the inlet 302 of the conduit 301 to provide said primary air. The feeding chamber 8 also or alternatively can be in fluid communication with the passage 4 to provide said secondary air.

The heating apparatus 1 comprises a wall 401 having a first face 402 and a second face 403, opposite to the first face 402. The first face 402 delimits the feeding chamber 8 and the second face 403 delimits the combustion chamber 2. The wall 401 has a plurality of apertures 404 defining the passage 4. In an embodiment, the size of said apertures 404 is optimized according to the desired flow of secondary air towards the combustion chamber 2.

The heating apparatus 1 further comprises a gas injector 9. The gas injector 9 is configured for injecting the combustible gas into the inlet 302 of the conduit 301. Here, the gas injector 9 is positioned inside the feeding chamber 8.

The gas injector 9 is connected to a gas tank 901 configured to stock the combustible gas. In the illustrated embodiment, the gas tank 90 i is positioned inside the reeding chamber 8.

The wall 401 is oriented in a vertical direction V, parallel to the weight force. The conduit 301 , at least in its end, is elongated in a horizontal direction H perpendicular to the weight force.

The fan 7 is configured for forcing the flow of secondary air into the combustion chamber 2 substantially along the horizontal direction H.

As illustrated, the burner can comprise one or more parallel burner modules 31 (see Fig. 7A). Each of the further parallel burner modules 31 comprises one parallel conduit 311. Each of the parallel conduits 311 has an inlet port 312, for receiving the mixture of primary air and combustible gas, and an outlet port 313, opened to the combustion chamber 2 to generate a flame in the combustion chamber 2. Here, each of the parallel conduits 301 and 311 is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. The parallel burner modules 31 are arranged in parallel with said burner module 3. The feeding chamber 8 is in fluid communication with the inlet port 312 of the one or more parallel conduits 31 . In the illustrated embodiment, the inlet ports 312 of the one or more parallel conduits

311 are positioned inside the feeding chamber 8.

The apparatus comprises a respective parallel gas injector 91 for each of the one or more parallel burner modules 31. The parallel gas injectors 91 are configured to inject the combustible gas into the inlet ports

312 of the one or more parallel conduits 311.

Here, the parallel gas injectors 91 also are positioned inside the feeding chamber 8 and are connected to the gas tank 901.

The passage 4 is configured to provide the flow of secondary air into the combustion chamber 2 at the outlet of the one or more parallel conduits 311.

Preferably, the apparatus also includes a parallel igniter 314 for each parallel burner module 31.

Here, the flow of secondary air flows externally to the conduit 301 and to the one or more parallel conduits 311.

In the illustrated embodiment, the heating apparatus 1 comprises an additional burner with an additional combustion chamber 2A. The additional burner comprises at least one additional burner module 3A with an additional conduit 301A. The additional conduit 301A has an inlet port 302A, for receiving an additional mixture of primary air and additional combustible gas, an outlet port 303A, opened to the additional combustion chamber 2A and an igniter 304A to generate a flame in the additional combustion chamber 2A. Here, the heating apparatus 1 also comprises an additional passage 4A. The additional passage 4A is configured to provide an additional flow of secondary into the additional combustion chamber 2A.

The heating apparatus 1 further comprises an additional wall 401 A having a first face 402A and a second face 403A, opposite to the first face 402A. The first face 402A of the additional wall 401A delimits the additional feeding chamber 8A and the second face 403A of the additional wall 401 A delimits the additional combustion chamber 2A. The additional wall 401A has a plurality of apertures defining the additional passage 4A. The size of said apertures 404A in the additional wall 401 A is optimized according to the desired additional flow of secondary air towards the additional combustion chamber 2A.

The heating apparatus 1 includes an additional duct 5A, for conveying an additional fluid to be heated. The additional fluid to be heated for example can be a liquid like water. The additional duct 5A has an inlet 501 A, an outlet 502A and is at least partially configured as heat transfer tank 504A. Here, the heating apparatus 1 includes an additional fluid pump. The additional fluid pump is configured to force the additional fluid flowing through the additional duct 5A from the inlet 501 A to the outlet 502A. In the illustrated embodiment, the additional pump is a liquid pump.

The heating apparatus 1 also includes a heat transfer unit 6A configured for transferring heat from exhaust gases flowing through a gas conduit 60A of the heat transfer unit 6A to the additional fluid flowing through the additional duct 5A.

The gas conduit 60A of the heat transfer unit 6A has a gas inlet 603A, a gas outlet 604A and two zones: A first heat transfer zone 601 A is configured to transfer heat from the heated exhaust gases, generated in the additional combustion chamber 2A, and fluid within the additional duct 5A, here in form of a heat transfer tank 504A, in particular water within the heat transfer tank 504A of the additional duct 5A, being surrounded by a corresponding chamber. A second heat transfer zone 602A is also configured to transfer heat from the heated exhaust gases, generated in the additional combustion chamber 2A, and fluid, in particular water within the heat transfer tank 504A of the additional duct 5A, and being surrounded by a corresponding gas pipe. The additional combustion zone 2A at least partially can be provided as section of the first heat transfer zone 601 A. The chamber surrounding the first heat transfer zone 601 A is coupled to the gas inlet 603A, the gas pipe surrounding the second heat transfer zone 602A is coupled to the chamber surrounding the first heat transfer zone 601A and the gas outlet 604A is coupled to the gas pipe surrounding the second heat transfer zone 602A.

The gas conduit 60A is geometrically shaped so that due to convection, heated gas entering the gas conduit 60A at ti^'ie gas inlet 603A at first nas to flow through the first heat transfer zone 601 A and then through the second heat transfer zone 602A before it can leave the gas conduit 60A through the gas outlet 604A. The chamber surrounding the first heat transfer zone 601A and the gas pipe surrounding the second heat transfer zone 602A are provided within the heat transfer tank 504A of the additional duct 5A.

According to the present invention, the chamber surrounding the first heat transfer zone 601A is provided as triangular chamber and the gas pipe surrounding the second heat transfer zone 602A is coupled to the triangular chamber surrounding the first heat transfer zone 601 A in the area of one of its corners.

In the illustrated embodiment, the triangular chamber surrounding the first heat transfer zone is formed of two identical components coupled to each other in a mirrored manner and forming a to surface, a bottom surface and the rectangular side surfaces, wherein the gas inlet 603A is coupled to one of the side surfaces and the gas pip surrounding the second heat transfer zone 602A is coupled to the corner of the triangular chamber being positioned opposite the location of the gas inlet 603A. Although this configuration has many advantages with regard to the achieved gas flow, also other configurations like triangular side surfaces would be possible.

The triangular chamber is oriented horizontal within the heat transfer tank 504A, but it also could be provided tilted to improve the effect of convection on the heated gas.

Here, the heating apparatus 1 comprises an additional fan 7A configured for forcing the additional flow of secondary air through the additional passage 4.

In the illustrated embodiment, the heating apparatus 1 comprises an additional feeding chamber 8A configured to receive air from the external environment. The additional fan 7A is provided within the passage 4 or like illustrated here at the inlet of the additional feeding chamber 8A to force air from the external environment into the feeding chamber 2A.

The additional feeding chamber 8A is in fluid communication with the inlet 302A of the additional conduit 301A to provide said primary air. The additional feeding chamber 8A also or alternatively can be in fluid communication with the additional passage 4A to provide said additional flow of secondary air.

The heating apparatus 1 further comprises an additional gas injector 9A. The additional gas injector 9A is configured for injecting the additional combustible gas into the inlet 302A of the additional conduit 301A. Here, the additional gas injector 9A is positioned inside the additional feeding chamber 8A.

The additional gas injector 9A is connected with an additional gas tank 901A configured to stock the additional combustible gas. In the illustrated embodiment, the additional gas tank 901 A is positioned inside the additional feeding chamber 8A.

In an embodiment, the additional wall 401A is oriented in the vertical direction V. The additional conduit 301A, at least in its end, is elongated in the horizontal direction H.

The additional fan 7A is configured for forcing the additional flow of secondary air into the additional combustion chamber 2A substantially along the horizontal direction H.

The heating apparatus 1 also comprises at least one feeding mouth 10 being in communication with the external environment. The at least one feeding mouth 10 has a main inlet 101 opened to the external environment. The at least one feeding mouth 10 also has an outlet communicating with the feeding chamber 8 through the fan 7 and/or an additional outlet communicating with the additional feeding chamber 8A through the additional fan 7A. An electric board 12 is positioned inside the at least one feeding mouth 10. The heating apparatus 1 further includes an exhaust gases pipe 11.

The combustion chamber 8 and the additional combustion chamber 8A are in fluid communication with the exhaust gases pipe 11 via the corresponding combustion chambers 2 and 2A and the gas conduits 60 and 60A of the corresponding heat exchanger 6 respectively heat transfer unit 6A. The exhaust gases pipe 11 has an end opened to the external environment.

As illustrated, the exhaust gases pipe 11 is partially surrounded by the main inlet 101 of the at least one feeding mouth 10 such that the exhaust gases flowing through the exhaust gases pipe 11 release heat to the air entering into the at least one feeding mouth 10 to increase the overall efficiency of the heating apparatusl .

The heating apparatus 1 further includes a gas valve 13 and a parallel gas valve 131 for each parallel burner module 31. The gas valve 13 is connected to the gas injector 9 and the parallel gas valves 131 are connected to the parallel gas injectors 91.

The heating apparatus 1 includes an additional gas valve connected to the additional gas injectors 9A. The heating apparatus 1 comprises a single control unit connected to the fan 7. The control unit further is connected to the additional fan 7A and to the gas injector 9. The control unit also is connected to the additional gas injectors 9A, the fluid pump 503 and the additional fluid pump 503A.

The control unit is configured for controlling and coordinating the fan 7, the gas injector 9 and the fluid pump 503 as well as the additional fan 7A, the additional gas injector 9A and the additional fluid pump 503A.

The illustrated heating apparatus 1 includes a fluid temperature sensor, for measuring a temperature of the fluid (that preferably is air). The fluid temperature sensor can be placed inside the recreational vehicle in which the heating apparatus is provided, to measure the temperature of the fluid (air) inside the recreational vehicle. Alternatively, the fluid temperature sensor can be placed outside the recreational vehicle to measure the temperature of the fluid (air) outside the recreational vehicle. The fluid temperature sensor is connected to the control unit.

Here, the heating apparatus includes an additional fluid temperature sensor, for measuring a temperature of the additional fluid (that preferably is water). The additional fluid temperature sensor is placed in a water tank containing the water that has to be fed to the heating apparatus. The additional fluid's temperature sensor also is connected to the control unit.

The control unit is connected to the gas valve 13 and to the parallel gas valves 131 as well as to the additional gas valve.

The control unit is connected to the fan 7 and is configured to control the fan 7. Here, the control unit is programmed to control the fan 7 in dependence of at least one control parameter, wherein the control parameter is representative for a thermal power provided by the burner. The control parameter may be set (directly or indirectly) by the user through an interface. The control parameter also may be derived as a function of a target temperature (which can be set by the user through the interface) and of a measured parameter, which may be representative for the temperature of the fluid (or additional fluid) to be heated (at input to the heater). As illustrated, the burner preferably includes a plurality of burner modules (for example

2, 3, 4, or more); here assuming it includes N modules; the heater is configured to turn on a subset of the plurality of burner modules, keeping the remaining ones off. In this case, the control parameter may be representative of a number (any natural number from 0 to N), corresponding to the number of burner modules to be set on, wherein the others are to be set off (or vice versa). The same features may (or may not) be provided to the additional burner.

In the illustrated embodiment, the control unit further is programmed for receiving (from the fluid temperature sensor) the temperature of the fluid, for comparing it with a target temperature of the fluid. The target temperature of the fluid can be set by a user. The control unit also is programmed for receiving (from the additional fluid temperature sensor) the temperature of the additional fluid, for comparing it with the target temperature of the additional fluid. T he target temperature of the additional fluid can be set by a user. The control unit is programmed for controlling the burner, switching on or off (selectively) one or more of the burner modules 3, if the temperature of the fluid is lower than the target temperature of the fluid. The control unit is programmed for controlling the additional burner, switching on or off (selectively) one or more of the additional burner modules 3A, if the temperature of the additional fluid is lower than the target temperature of the additional fluid.

The control unit is programmed for controlling the burner, switching off one or more of the burner modules

3, 31 if the temperature of the fluid is equal or higher than the target temperature of the fluid. In an embodiment, the control unit is programmed for controlling the additional burner, switching off one or more of the additional burner modules 3A if the temperature of the additional fluid is equal to or higher than the target temperature of the additional fluid. The heating apparatus includes a panel where the user can manually set the number of the burner modules 3, 31 that he wants to switch on or off. In addition thereto, the heating apparatus includes a panel where the user can manually set the number of the additional burner modules 3A that he wants to switch on or off.

The number of burner modules 3, 31 switched on (or off) provides a parameter representative for a thermal power provided by the burner. The difference between the target temperature of the fluid (air) and the measured temperature of the fluid (air) provides another parameter representative for a thermal power provided by the burner.

The number of additional burner modules 3A switched on (or off) provides a parameter representative for a thermal power provided by the additional burner. The difference between the target temperature of the additional fluid (water) and the measured temperature of the additional fluid (water) provides another parameter representative for a thermal power provided by the additional burner.

The control unit is configured to receive at least one parameter representative for the thermal power provided by the burner and one parameter representative for the thermal power provided by the additional burner.

The control unit is connected to the fan 7 and configured to control the fan 7 in dependence to the at least one parameter representative for a thermal power provided by the burner.

Moreover, the control unit is connected to the additional fan 7A and configured to control the additional fan 7A in dependence to the at least one parameter representative for a thermal power provided by the additional burner.

The control unit switches on the burner module 3, 31 by opening the gas valve 13 and switches off the burner module 3 by closing the gas valve 13. The control unit switches on the additional burner module 3A by opening the additional gas valve and switches off the additional burner module 3A by closing the additional gas valve.

The present invention covers a heat exchanger, a heating unit with such a heat exchanger, a heating apparatus with such a heat exchanger and/ or heating unit and a recreational vehicle comprising the heating apparatus 1 , one of the described heating units, the described heat exchanger and/ or the described heat exchanger.

The heating apparatus 1 can be fixable outside the recreational vehicle like for example on the roof of the recreational vehicle. Some further preferable features and some clarifications are given in the following.

Preferably, the burner (the burner module 3) is an atmospheric burner; this means that the burner, per se, does not require a pre-mixing unit, for providing the mixture of air and gas to be fed to the burner itself.

Preferably, the burner (the burner module 3) is a "bladed" or "ramp-type" burner, which is a low-cost commercial component.

Preferably, the gas injector 9 is positioned in the immediate vicinity of the inlet port 302 of the conduit (preferably less than 60 millimeters, more preferably less than 20 millimeters from the inlet of the conduit). The conduit 301 , at the inlet port 302 thereof, preferably has a stretch oriented (extended) along a first axis. In an embodiment, the gas injector 9 is oriented along that first axis, substantially aligned with the stretch of the burner positioned proximate to the inlet port 302 of the conduit 301.

At the inlet port 302 of the conduit 301 , (primary) air is sucked naturally, together with the gas provided by the injector 9; hence, the mixture of air and gas is provided naturally at the inlet port 302 of the conduit 301 , by Venturi effect.

Preferably, the nozzles (apertures 404) provided at the outlet port 303 of the conduit 301 are oriented in respective second axes. In an embodiment, the second axes of the nozzles are parallel to each other. In another embodiment, the second axes of the nozzles are transversal (perpendicular) to the first axis. In one embodiment, the second axes are oriented in a same plane which includes the first axis.

The primary air is necessary to have combustion in a flammability range, the secondary air is adduced to the flames to optimize the combustion efficiency, to reduce the harmful emissions and to control the temperature of the combustion chamber.

Preferably, the fluid to be heated is breathable air. For breathable air, it is intended the air that people in the recreational vehicle are going to breath. Moreover, the fluid to be heated is water. For water, it is intended the water that people in the recreational vehicle are going to use for sanitary purposes, for cleaning or for cooking.

The suction of primary air preferably is naturally provided by the Venturi effect, while the aspiration of secondary air is forced by the fan. This combination of natural and forced aspiration improves the efficiency and the flexibility of the heating apparatus. Preferably, transversally to the feeding direction, the feeding chamber has a section (size) which is significantly larger (for example at least 3 times, preferably at least 5 times, for example approximately ten times) than the section of the conduit inlet port (for primary air and gas). In one preferably embodiment, the feeding direction is transversal to the first axis (along which the inlet of the conduit extends).

Preferably, the number of the burner modules 3, 31 is greater than the number of the additional burner modules 3 A.

In a preferred embodiment, in which the fluid is breathable air and the additional fluid is water, the number of burner modules 3, 31 (dedicated to the heating of the air) is three and the number of additional burner modules 3A (dedicated to the heating of the water) is one. This embodiment reflects the average request for warm air and warm water in a recreational vehicle.

The structure of the heating apparatus 1 , with two distinct combustion chambers 2 and 2A and two distinct heat exchangers 6 respectively heat transfer units 6A, the one dedicated to the water, and the other dedicated to the air, gives to the apparatus a high flexibility and a good efficiency. Actually, it is possible to heat air but not water, and to heat water but not air.

Preferably, the heating apparatus 1 is fixable on the roof of the recreational vehicle. This placement outside the recreational vehicle is possible because of the high efficiency of the apparatus 1 and because of the main horizontal size of the apparatus 1 , thanks to the fan configured for flowing secondary air along the horizontal direction. This placement outside the recreational vehicle allows to have more available place inside the recreational vehicle.

Preferably, the heating apparatus 1 includes an automatic frost valve. The automatic frost valve is connected to a water circuit, that also includes the additional duct. The automatic frost valve is configured for automatically opening when the recreational vehicle is parked in response to a cold temperature detection, allowing the water to flow away. This feature avoids the freezing damaging the water circuit.

The automatic frost valve is configured for automatically setting back to close when the water circuit is empty. This feature avoids someone having to close the valve. REFERENCE SIGNS : heating apparatus

: combustion chamber

A: additional combustion chamber

: burner module

01 : conduit

02: inlet port

03: outlet port

04: igniter

1 : parallel burner module

1 1 : parallel conduit

12: inlet port

13: outlet port

14: igniter

A: additional bumer module

01 A: additional conduit

02A: inlet port

03A: outlet port

04A: igniter

: passage

01 : wall

02: first face

03: second face

04: aperture

A: additional passage

01 A: additional wall

02A: first face

03A: second face

: duct

01 : inlet

02: outlet

03: fluid pump

A: additional duct

01 A: inlet

02A: outlet

03A: additional fluid pump 504A: heat transfer tank

6: heat exchanger

60: gas conduit

601 : first heat exchange zone

602: second heat exchange zone

603: gas inlet

604: gas outlet

6A: heat transfer zone

60A: gas conduit

601 A: first heat exchange zone

602A: second heat exchange zone

603A: gas inlet

604A: gas outlet

7: fan

7A: additional fan

8: feeding chamber

8A: additional feeding chamber

9: gas injector

901 : gas tank

9A: additional gas injector

901 A: additional gas tank

91 : parallel gas injector

10: feeding mouth

11 : exhaust gases pipe

101 : main inlet

12: electric board

13: gas valve

131 : parallel gas valve

H: horizontal direction

V: vertical direction

Claims

Heat transfer unit (6A) for a heating apparatus (1 ) for a recreational vehicle for transferring heat from a heated gas to a liquid, in particular to water, comprising:

a gas conduit (60A) configured to receive and transfer the heated gas; and

a heat transfer tank (504A) configured to contain the liquid,

wherein the gas conduit (60A) has a gas inlet (603A), a gas outlet (604A) as well as a first heat transfer zone (601 A) surrounded by a corresponding chamber and a second heat transfer zone (602A) surrounded by a corresponding gas pipe, wherein the chamber surrounding the first heat transfer zone (601 A) is coupled to the gas inlet (603A), the gas pipe surrounding the second heat transfer zone (602A) is coupled to the chamber surrounding the first heat transfer zone (601 A) and the gas outlet (604A) is coupled to the gas pipe surrounding the second heat transfer zone (602A), wherein the gas conduit (60A) is geometrically shaped in such a way that due to convection, heated gas entering the gas conduit (60A) at the gas inlet (603A) at first has to flow through the first heat transfer zone (601 A) and then through the second heat transfer zone (602A) before it can leave the gas conduit (60A) through the gas outlet (604A),

wherein the chamber surrounding the first heat transfer zone (601 A) and the gas pipe surrounding the second heat transfer zone (602A) are provided within the heat transfer tank (504A),

characterized in that

the chamber surrounding the first heat transfer zone (601 A) is provided as triangular chamber and the gas pipe surrounding the second heat transfer zone (602A) is coupled to the triangular chamber surrounding the first heat transfer zone (601 A) in the area of one of the corners of the triangular chamber.

Heat transfer unit (6A) according to claim 1 ,

wherein the triangular chamber surrounding the first heat transfer zone (601 A) has a triangular bottom surface, a triangular top surface and three in particular rectangular side surfaces connecting the triangular bottom surface to the triangular top surface at the three sides of the two triangular surfaces,

wherein a gas inlet (603A) is provided along a first side surface of the triangular chamber, and wherein the gas pipe surrounding the second heat transfer zone (602A) is coupled to the opposite end of the triangular chamber, and in particular to the top surface of the triangular chamber near the location, where the second side surface and the third side surface touch each other.

Heat transfer unit (6A) according to claim 2,

wherein the triangular chamber surrounding the first heat transfer zone (601 A) is arranged horizontal within the heat transfer tank, or wherein the triangular chamber is arranged ascending from the first side surface of the triangular chamber to the location, where the gas pipe surrounding the second heat transfer zone (602A) is coupled to the triangular chamber within the heat transfer tank (504A).

Heat transfer unit (6A) according to any one of the preceding claims,

wherein the triangular chamber surrounding the first heat transfer zone (601 A) is formed of two identical components, which are fixed together mirrored against each other to form the triangular chamber.

Heating unit for heating liquid for a heating apparatus (1 ) of a recreational vehicle, the heating unit comprising:

a heat transfer unit (6A) according to any one of the preceding claims; and

a burner coupled to the heat transfer unit (6A),

wherein the burner comprises at least one burner module (3A) and a combustion chamber (2A) with an igniter (304A),

wherein the burner module (3A) has a conduit (301A) with an inlet port (302A) for receiving a mixture of primary air and combustible gas, and an outlet port (303A) leading to the combustion chamber (2A), wherein the outlet port (303A) in particular is a line of nozzles, and the conduit (301 A) in particular is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect,

wherein the combustion chamber (2A) is coupled to the gas inlet (603A) of the gas conduit (60A) of the heat transfer unit (6A) or wherein the combustion chamber (2A) of the burner is provided at least partially as section of the triangular chamber surrounding the first heat transfer zone (601 A).

Heating unit according to claim 5,

wherein the burner comprises a passage (4A) configured to guide a flow of secondary air into the combustion chamber (2A), and

wherein in particular a fan (7A) configured for forcing the flow of secondary air into the combustion chamber (2A) is provided near or within the passage (4A).

Heating apparatus (1 ) for a recreational vehicle, comprising:

a first heating unit according to any one of claims 5 and 6, or

a first heating unit having a first burner and a thereto coupled heat transfer unit (6A) according to any one of the preceding claims 1 to 4;

a main inlet (101 ) for supplying the first heating unit with air; and

an exhaust gases pipe (11 ) for discharging exhaust gases form the heating apparatus (1).

8. Heating apparatus (1 ) according to claim 7, further comprising:

an additional heating unit having a burner and a heat exchanger (6), coupled to the additional burner,

wherein the additional heating unit is connected in parallel with the first heating unit to the main inlet (101) and the exhaust gases pipe (11 ) of the heating apparatus (1).

9. Heating apparatus (1 ) according to any one of the preceding claims 7 and 8,

wherein the first heating unit and the second heating unit are arranged side by side or one above the other within the heating apparatus (1 ).

10. Recreational vehicle comprising

a heating apparatus (1 ) according to any one of the preceding claims 7 to 9,

a heating unit according to any of the preceding claims 5 and 6, and/ or

a heat transfer unit (6A) according to any of the preceding claims 1 to 4.