Patent Description:
Heating plants have been long known, which comprise a thermal device having a burner connected to at least one closed loop for heating an environment by radiation.

The burner is generally adapted to generate heat by combustion of a fuel-air mixture for heating a working fluid circulated in the heating circuit. In addition, the burner is connected to a chimney which is adapted to filter and the combustion products into the atmosphere.

Nevertheless, this kind of plant has a relatively low efficiency, as the latter depends on the calorific value of the fuel-air mixture, and does not allow recovery of the sensible and latent heat of combustion products.

Some of these plants include, as is well known, one or more heat pumps instead of thermal devices with a burner for ambient heating.

Nevertheless, in this configuration the heat pumps have the drawback of having a low performance coefficient during periods of the year in which external temperatures are lower.

Furthermore, a further drawback is the thermal stratification created by heat pumps when the environments to be heated have a remarkably high ceiling, such as in industrial environments.

This drawback requires plants to be particularly complex and oversized for efficient heating of the environment even at people's level.

In an attempt to at least partially obviate this drawback, heating plants have been developed which comprise devices that are able to recover sensible and latent heat from the combustion products and reintroduce it into the environment and heat-radiating devices that afford uniform heating of the environment.

<CIT> discloses a heating plant which comprises a condenser having a chimney for recovering sensible and latent heat from the combustion products by means of a secondary fluid, and later introducing it into the environment.

In addition, the plant comprises a first heat-radiating thermal device located inside the environment and connected to a burner and a second thermal device in fluid communication with the condenser to receive the hot secondary fluid, and also placed inside the environment to heat it in combination with the first thermal device.

A first drawback of this arrangement is that this plant can only partially increase heating efficiency.

A further drawback of this arrangement is that the burner only uses non-renewable energy sources, in particular for supplying energy to the burner of the first heat-radiating thermal device.

A further drawback of this arrangement is that this plant cannot afford cooling the environment during the summer period.

<CIT> refers to a "heating plant particularly intended for utilising additional heat from ambient atmosphere, especially during the summer", see page <NUM>, lines <NUM>-<NUM>. It comprises an electric heater intended to supply the heat normally demanded during the summer season. The heating plant comprises a heating boiler, a first and a second heat exchanger, a heat pump not reversible, for heating either the exhaust gases from the heating boiler or other heating fluids.

In addition, these hybrid plants comprise a device for recovering latent heat from the combustion products of the first thermal device and means for fluid connection configured for selective connection of the first or second thermal device with the heat pump for heating, in combination with the first thermal device.

A drawback of these known arrangements is that the first and second heating devices are placed in two distinct and separate environments to be heated, thereby decreasing heating effectiveness and efficiency.

A further drawback of these arrangements is that the first thermal device and the heat recovery device are situated inside the environment to be heated, which increases the risks associated with the introduction of hazardous materials, such as gas or fuels, into the environment, and combustion products that are harmful to the user.

In the light of the prior art, the technical problem addressed by the <NUM> present invention is to provide a hybrid ambient-air conditioning plant that selectively affords efficient and uniform heating of an environment during the winter and cooling of the same environment during the summer, while also utilising renewable energy sources.

The object of the present invention is to obviate the above drawback, by providing a hybrid ambient-air conditioning plant that is highly efficient and relatively cost-effective.

A particular object of the present invention is to provide a plant as described hereinbefore that can ensure both heating and cooling of an indoor environment.

A further object of the present invention is to provide a plant as described hereinbefore that has a very high thermal efficiency.

Another object of the present invention is to provide a plant as described hereinbefore that can uniformly heat environments having high ceilings.

A further object of the present invention is to provide a plant as described hereinbefore, that can reduce the overall fossil fuel consumption, by also using renewable energy sources.

Another object of the present invention is to provide a plant as described above that is very simple to use and has low operation costs.

Yet another object of the present invention is to provide a plant as described hereinbefore that can reduce emissions of polluting gases into the atmosphere.

These and other objects, as more clearly explained hereinafter, are fulfilled by a hybrid ambient-air conditioning plant for civil or industrial use as defined in claim <NUM>.

The arrangement defined in claim <NUM> affords efficient and uniform heating of an environment during the winter and cooling of the same environment during the summer.

In a preferred embodiment, the connection means comprise a first three-way valve which is adapted to connect either the first or the second secondary circuits to the inlet of the second thermal device, and a second three-way valve configured for connecting the first or the second secondary circuits to the outlet of the second thermal device.

In addition, the heat pump is adapted to be connected in series with the condenser and the second heating device and to be put in fluid communication with the first secondary circuit.

In a further embodiment, the connection means comprise one or more valves located in the first secondary circuit and configured to selectively connect the condenser and the heat pump when the latter is in the ambient heating mode.

Furthermore, the plant may comprise a heat accumulator in fluid communication with the first and the second secondary circuits and fluidically connected to the second thermal device for conveying the fluid accumulated, heated or cooled by the heat pump or heated by the condenser, toward the second thermal device.

Also, in another embodiment, the connection means comprise, for each secondary circuit, at least two two-way valves for selectively connecting the condenser and the heat pump with the accumulator.

Preferably, the heat pump is an air-to-water, water-to-water, air-to-air or water-to-air heat pump.

Advantageous embodiments of the invention are obtained in accordance with the dependent claims.

Further features and advantages of the invention will be more apparent from the detailed description of a preferred, non-exclusive embodiment of an improved hybrid ambient air-conditioning plant, which is described as a nonlimiting example with the help of the annexed drawings, in which:.

Particularly referring to the figures, there is shown a hybrid plant, generally designated by numeral <NUM>, for ambient-air conditioning of an indoor environment, i.e. a medium-to-large civil environmentAor a high-volume industrial environment.

In a preferred embodiment of the invention, the plant <NUM> comprises at least one first thermal device <NUM> comprising a burner <NUM> for burning a fuel-air mixture, e.g. with methane, butane, propane or gasoil as fuels.

Namely, the burner <NUM> comprises a combustion chamber <NUM> with an inlet for the mixture and a discharge opening <NUM> for the products E generated by combustion of the mixture.

The combustion products E may have a predetermined combustion temperature, according to the type of mixture that is used in the burner <NUM>.

Advantageously, the burner <NUM> may comprise one or more control devices, not shown, which may be operated by an operator to adjust the operating combustion conditions in the chamber <NUM>.

Furthermore, the plant <NUM> comprises a closed circuit <NUM> containing a first working fluid F1 heated by the burner <NUM>, which is composed of a first pipe <NUM> with a delivery branch <NUM>' and a return branch <NUM>".

The closed circuit <NUM> may be of radiant type, mounted to the ceiling of the environment A to heat it by radiation.

Furthermore, in an alternative configuration of the invention, not shown, the closed circuit <NUM> may comprise a plurality of inlet ports arranged along the entire pipe <NUM> which may comprise respective fans adapted to act, when needed, as destratification fans, and a fan gate or a similar element.

In a first configuration of the invention, the first working fluid F1 in the closed circuit <NUM> may be composed of combustion products E such as exhaust air and gases.

For example, the first working fluid F1 may be overheated and circulated under negative pressure in the closed circuit <NUM> directly connected to the burner <NUM> and can generate variable surface radiation temperatures, as needed. Namely, the surface temperatures may range from <NUM> cc to <NUM> cc.

Alternatively, the first thermal device <NUM> may comprise a steam generator, not shown, operably associated with the burner <NUM> and fluidically connected to the closed circuit <NUM>.

In this arrangement, the first working fluid F1 may consist of the steam produced by the steam generator and the circuit <NUM> may be composed of a ceiling-, wall- or floor-mounted pipe <NUM> located in the environment A.

Furthermore, the plant <NUM> comprises a chimney <NUM> for ejecting the combustion products E of the burner <NUM>, in fluid communication with the discharge opening <NUM> of the combustion chamber <NUM>.

In addition, the chimney <NUM> comprises a condenser <NUM> for at least partial recovery of sensible and latent heat developed from evaporation of the combustion products E, which has a heat-exchange chamber <NUM>.

The chimney <NUM> and the condenser <NUM> may be placed at the first thermal device <NUM> or at any point of the circuit <NUM> according to the optimization requirements associated with the extent, the geometry, the presence of junctions and the sealing conditions of the circuit <NUM>.

As shown in the figures, the first thermal device <NUM> and the condenser <NUM> are placed outside the indoor environment A to be air-conditioned to avoid the risk of introducing fluid fuels and combustion products into the environment, which might be highly dangerous and hazardous for users.

The plant <NUM> comprises at least one second thermal device <NUM>. In particular, the second thermal device <NUM> is adapted to ensure air conditioning of the environment A by convection or radiation and may comprise a box-like body <NUM> with an air-conditioning circuit <NUM> therein and means, not shown, for forced convection of outside air or water.

In certain preferred, non-exclusive embodiments of the invention, the second thermal device <NUM> may comprise one or more fan heaters, or one or more induction devices for channeled air distribution or alternatively one or more radiant strip heaters.

The condenser <NUM> comprises a first secondary circuit <NUM> containing a first secondary fluid F2 and operably connected to the second thermal device <NUM> for at least partially returning the recovered heat to the environment A by means of the first secondary fluid F2.

As shown in <FIG>, the first secondary circuit <NUM> may comprise a second pipe <NUM> placed inside the heat-exchange chamber <NUM> of the condenser <NUM> such that the combustion products E generated by the burner <NUM> will flow over its outer surface.

In order to maximise the heat-exchange area of the first secondary circuit <NUM> with the combustion products E, the second pipe <NUM> in the heat exchange chamber <NUM> may comprise one or more coils and the first secondary fluid F2 may consist of a liquid, e.g. water and/or glycol, or a gas, such as air.

Furthermore, a plurality of baffles <NUM>' may be installed in the heat-exchange chamber <NUM> for increasing the turbulence of the combustion products E and further improve the efficiency of the plant <NUM>.

In a first embodiment as shown in <FIG>, the first secondary circuit <NUM> may comprise a secondary delivery branch <NUM>' for directly connecting the outlet 15B of the second pipe <NUM> to the inlet 11A of the second thermal device <NUM> and a secondary return branch <NUM>' for directly connecting the outlet 11b of the second thermal device <NUM> to the inlet 15a of the second pipe <NUM>.

Conveniently, the second thermal device <NUM> may be fluidically connected to the inlet 15a of the second pipe <NUM> with suitable pumping means <NUM> interposed therebetween, for pumping the first secondary fluid F2, which are located in the secondary return branch <NUM>".

Alternatively and equivalently, the pumping means <NUM> may be placed on the delivery branch <NUM>'.

These pumping means <NUM> may include either a pump or a similar device if the first secondary fluid F2 is a liquid, or a compressor or a similar device if the first secondary fluid F2 is a gas.

As shown in the figures, the plant <NUM> comprises a heat pump <NUM> having a second secondary circuit <NUM> containing a second secondary fluid F3, and operably connected to the second thermal device <NUM>.

Advantageously, the heat pump <NUM> may be positioned either outside or inside the environment A to be air-conditioned, without departure from the scope of the present invention.

In a peculiar aspect of the invention, the closed circuit <NUM> and the second thermal device <NUM> are placed in the same environment A to be air conditioned and the heat pump <NUM> is adapted to selectively operate in heating or cooling mode.

Furthermore, the plant <NUM> comprises fluid connection means <NUM> for selectively connecting the second thermal device <NUM> with the first secondary circuit <NUM> and with the heat pump <NUM> for ambient heating in combination with the first thermal device <NUM>.

The fluid connection means <NUM> are also configured to selectively connect the second thermal device <NUM> with the heat pump <NUM> for cooling the environment A.

As shown in the figures, the closed circuit <NUM> is fluidically independent from the first secondary circuit <NUM> and the second secondary circuit <NUM>.

Thus, the second thermal device <NUM> in the environment A will heat the environment either in cooperation with the first thermal device <NUM> or independently, or cooling it.

Accordingly, the second device <NUM> connected to the heat pump <NUM> in heating mode may operate in combination with the first thermal device <NUM> for the plant <NUM> to heat the environment A with increased efficiency as compared with the operation of the first thermal device <NUM> alone.

Furthermore, if the environment A has a very high ceiling, like in industrial environments, this configuration prevents the creation of temperature stratifications thereby affording uniform and comfortable heating at people's level.

Alternatively, in the cooling mode, the heat pump <NUM> may operate to allow the plant <NUM>, particularly the second thermal device <NUM>, to independently cool the environment.

As is known per se, the heat pump <NUM> may be electrically or gas operated and may be configured to transfer thermal energy to the second secondary circuit <NUM> from a source external to the environment to be air conditioned. Thus, the heat pump <NUM> may be an air-to-water, water-to-water, air-to-air or water-to-air heat pump.

In addition, the heat pump <NUM> may be supplied with the power produced by renewable energy sources, such as solar, photovoltaic and geothermal power plants, produced in situ or distributed by the national supply mains.

In the first embodiment as schematically shown in <FIG>, it may be appreciated that the first secondary circuit <NUM> is fluidically independent from the second secondary circuit <NUM> such that any failure in the operation of the heat pump <NUM> operating in heating mode will not impede the operation of the plant <NUM>.

The connection means <NUM> may comprise a first three-way valve <NUM> which is adapted to connect the first <NUM> and the second <NUM> secondary circuits to the inlet 11A of the second thermal device <NUM>, and a second three-way valve <NUM> configured for selective connection of the first <NUM> and of the second <NUM> secondary circuits to the outlet 11B of the second thermal device <NUM>.

The first three-way valve <NUM> is connected to the delivery branch <NUM>' of the first secondary circuit <NUM> and to a delivery branch <NUM>' of the second secondary circuit <NUM>, whereas the second three-way valve <NUM> is connected to the return branch <NUM>" of the first secondary circuit <NUM> and to a return branch <NUM>" of the second secondary circuit <NUM>.

In this embodiment, when the plant <NUM> operates in heating mode, the means for connection <NUM> will be configured to mix and adjust the flow of the first secondary fluid F2 with the second secondary fluid F3 to improve the operating efficiency of operation of the second thermal device <NUM>.

Alternatively, in the cooling mode the connection means <NUM> will be configured to stop the flow the first secondary fluid F2 and connect the second secondary circuit <NUM> to the inlet 11A and outlet 11B of the second thermal device <NUM>.

In a second exemplary embodiment, not falling under the scope of the claims as schematically shown in <FIG>, the heat pump <NUM> may be connected in series with the condenser <NUM> and the second heating device <NUM> and be interposed therebetween and may be in fluid communication with the first secondary circuit <NUM>.

Namely, the delivery branch <NUM>' of the first secondary circuit <NUM> will be adapted to directly connect the outlet 15B of the second pipe <NUM> to a first inlet 17a of the heat pump <NUM> and the return branch <NUM>" of the first secondary circuit <NUM> will be adapted to directly connect a first outlet 17b of the heat pump <NUM> to the inlet 15A of the second pipe <NUM>.

In addition, the delivery branch <NUM>' of the second secondary circuit <NUM> will be adapted to connect the inlet 11A of the second thermal device <NUM> to a second outlet 17c of the heat pump <NUM>, whereas the return branch <NUM>" of the second secondary circuit <NUM> will be adapted to connect the outlet 11B of the second thermal device <NUM> to a second inlet 17D of the heat pump <NUM>.

Conveniently, the connection means <NUM> may comprise one or more valves <NUM> located in the first secondary circuit <NUM> and configured to selectively connect the condenser <NUM> and the heat pump <NUM> when the latter is in the ambient heating mode.

The exemplary embodiment of <FIG> shows a first secondary circuit <NUM> comprising a pair of valves <NUM> located at the delivery branch <NUM> and the return branch <NUM>" respectively.

In the cooling mode, the heat pump <NUM> may be connected to a high temperature source of thermal energy and the connection means <NUM> will be closed.

Moreover, in this exemplary embodiment, not falling under the scope of the claims the pumping means <NUM> may comprise a first pump <NUM> located in the return branch <NUM>" of the first secondary circuit <NUM> and a second pump <NUM>" located in the return branch <NUM>" of the second secondary circuit <NUM>.

Alternatively, the first <NUM>' and second <NUM>" pumps may be placed in the delivery branches <NUM>', <NUM>' of the first <NUM> and the second <NUM> secondary circuits respectively, as described for the first embodiment.

In a third embodiment, as schematically shown in <FIG>, the plant <NUM> may comprise a heat accumulator <NUM> in fluid communication with the first <NUM> and the second <NUM> secondary circuits and connected to the second thermal device <NUM> for conveying the accumulated fluid F4, heated or cooled by the heat pump <NUM> or heated by the condenser <NUM>, toward the second thermal device <NUM>.

Namely, the delivery branch <NUM>' of the first secondary circuit <NUM> will be adapted to directly connect the outlet 15B of the second pipe <NUM> to a first inlet 23A of the accumulator <NUM> and the return branch <NUM>" of the first secondary circuit <NUM> will be adapted to directly connect a first outlet 23B of the accumulator <NUM> to the inlet 15A of the second pipe <NUM>.

The delivery branch <NUM>' of the second secondary circuit <NUM> will be adapted to connect the outlet 17C of the heat pump <NUM> to a second inlet 23C of the accumulator <NUM>, whereas the return branch <NUM>" of the second secondary circuit <NUM> will be adapted to connect a second outlet 23D of the accumulator <NUM> to an inlet 17D of the heat pump <NUM>.

Furthermore, a third outlet 23e of the accumulator <NUM> may be connected to the inlet 11A of the second thermal device <NUM> via a delivery branch <NUM>' of a third secondary circuit <NUM> whereas the outlet 11b of second thermal device <NUM> may be connected to a third inlet 23F of the accumulator <NUM> via a return branch <NUM>" of the third secondary circuit <NUM>.

Advantageously, the connection means <NUM> may comprise, for each secondary circuit <NUM>, <NUM>, at least two two-way valves <NUM>, <NUM> for selectively connecting the condenser <NUM> or the heat pump <NUM> with the accumulator <NUM>.

Alternatively, the heat pump <NUM> connected to the accumulator <NUM>, by operation of the fluid connection means <NUM> can afford cooling of the environment. In the cooling mode the two-way valves <NUM> are closed, whereas the two-way valves <NUM> are open.

In this embodiment the pumping means <NUM> may comprise a first pump <NUM> located in the return branch <NUM>" of the first secondary circuit <NUM> and a second pump <NUM>" located in the return branch <NUM>" of the third secondary circuit <NUM>.

Alternatively, the first <NUM>' and second <NUM>" pumps may be placed in the delivery branches <NUM>', <NUM>' of the first <NUM> and the third <NUM> secondary circuits respectively.

Advantageously, and independently of the embodiments as described above, a casing, not shown, may be provided for enclosing two or more of the components of the plant <NUM>, such as the first thermal device <NUM>, the condenser <NUM>, the heat pump <NUM>, the accumulator <NUM> and the second heating device <NUM>.

As is known per se, a control unit <NUM> may be provided, which is connected to the control devices of the burner <NUM>, the heat pump <NUM>, the pumping means <NUM> and the connection means <NUM>, to adjust the mixture percentages of the first <NUM> and second <NUM> secondary circuits as well as the temperature of the environment A.

Alternatively, the control unit <NUM> may be also connected to the accumulator <NUM>, in the case of the embodiment as shown in <FIG>.

The control unit <NUM> may be operably connected to a plurality of temperature sensors, not shown, for measuring the outside temperature, the temperature of the environment A and/or the temperature of the first F1 and/or of the first F2 and the second F3 secondary fluids and/or the accumulated fluid F4, in the case of the embodiment with the accumulator <NUM>.

Thus, the control unit <NUM> may control the overall operation of the plant <NUM> according to the temperature measurements made at various points thereof and may calculate the total efficiency of the plant <NUM> according to energy consumption and the use of renewable energy sources.

Moreover, the control unit <NUM> may stop fluid supply to the first <NUM> and/or of the second <NUM> secondary circuits in case of failure of the condenser <NUM> and the heat pump <NUM> respectively.

It will be appreciated from the foregoing that that ambient-air conditioning plant fulfils the intended objects and particularly affords efficient and uniform heating of an environment during the winter and cooling of the same environment during the summer.

Claim 1:
A hybrid plant (<NUM>) for ambient-air conditioning of an indoor environment (A) for civil or industrial use, which plant (<NUM>) comprises:
- at least one first thermal device (<NUM>) comprising a burner (<NUM>) which is adapted to heat a first working fluid (F1) contained in a closed circuit (<NUM>);
- a chimney (<NUM>) for ejecting the combustion products (E) of said burner (<NUM>);
- at least one second thermal device (<NUM>);
- at least one heat pump (<NUM>) having a second secondary circuit (<NUM>) containing a second secondary fluid (F3), and operably connected to said second thermal device (<NUM>);
wherein said chimney (<NUM>) comprises a condenser (<NUM>) for at least partial recovery of sensible and latent heat of evaporation of the combustion products (E);
wherein said condenser (<NUM>) comprises a first secondary circuit (<NUM>) containing a first secondary fluid (F2) and operably connected to said second thermal device (<NUM>) for at least partially returning the recovered heat to the environment (A) by means of the first secondary fluid (F2);
wherein said closed circuit (<NUM>) and said second thermal device (<NUM>) are placed in the same environment (A) to be air-conditioned, said heat pump (<NUM>) being adapted to selectively operate in heating or cooling mode, fluid connection means (<NUM>) being provided, for selectively connecting said second thermal device (<NUM>) with said first secondary circuit (<NUM>) and/or with said heat pump (<NUM>), and the condenser (<NUM>) for heating the environment (A) in combination with said first thermal device (<NUM>), or disconnecting it for allowing the heating of the environment (A) by means of the first thermal device (<NUM>) only, said fluid connection means (<NUM>) being further configured to selectively connect said second thermal device (<NUM>) with said heat pump (<NUM>) via the circuit (<NUM>) and disconnecting it from the condenser (<NUM>) either for cooling the environment (A) or heating it by means of the heating pump (<NUM>) only, said closed circuit (<NUM>) being fluidically independent from said first (<NUM>) and secondary (<NUM>) circuits.