WO2008038250A2

WO2008038250A2 - Air treatment unit, of dehumidification and heating energetically efficient

Info

Publication number: WO2008038250A2
Application number: PCT/IB2007/053938
Authority: WO
Inventors: Paulo Jorge MAGALHÃES PIRES
Original assignee: Universidade Do Porto
Priority date: 2006-09-27
Filing date: 2007-09-27
Publication date: 2008-04-03
Also published as: EP2066984A2; PT103572A; WO2008038250A3

Abstract

The Air Treatment Unit (ATU), of Energetically Efficient Dehumidification and Heating, is equipped with two heat exchangers (12, 19) fed by a Chiller and a boiler respectively and a thermic recuperator (13) between them. While crossing the three components, the forced air flow, actuated by ventilators (14, 21), reaches the humidity and filling temperature in the building for the internal conditions. Concerning this disposition, the ATU allows the use of the heat recuperator in heating periods of 100% of fresh air with/without air humidification (20- humidificator), dehumidification and heating of 100% fresh air or of the mixture of fresh air with addicted air, allowing the reduction of energetic consumption in air treatment. In periods of 100% of fresh air and forced ventilation cooling of the space, a 'bypass' is made for the heat recuperator. This unit assures the air quality inside buildings, avoiding, for example, problems of Legionella, chlorine concentrations on Covered Pools and of CO2 in buildings with humidity control.

Description

Description AIR TREATMENT UNIT, OF DEHUMIDIFICATION AND

HEATING ENERGETICALLY EFFICIENT

Scope of the Invention

[1] The present invention refers to an Air Treatment Unit with a heat recuperator Air- Air

(or Water- Water), with the objective to reduce power consumption in building air treatment, comprising interior humidity and temperature control, as well as to solve Interior Air Quality problems in some buildings.

[2] Presently, the air treatment units used in climate control systems of interior air have the heat recuperator for the energy exchange of fresh air at the unit's inlet for the air at the unit's outlet (to the exterior). Most buildings comprising humidity control use Heat Dehumification Pumps, but these might cause some inconvenient in terms of operation and control.

[3] The Air Treatment Units are dimensioned to the total or partial removal of the thermic charge of the space. Prior Art

[4] In a search of the prior art, the FR2742216 (BERNIER JACQUES FR) uses the heat recuperator between the evaporator and the heating pump condenser. It uses two heating pumps to solve the problem during the insufflation of 100% fresh air, but still presents with some negative operating aspects.

[5] Comparing the Heating Pump of FR2742216 with the developed unit, the present invention has multiple advantages such as:

I. Less charge lost at ventilation circuit (less power consumption) - smaller amount of heat exchangers in the developed air treatment unit, compared with the heating pump;

II. Less installed potency (smaller investment cost) - with the help of the heat exchanger it is possible to reduce installed potencies at heat exchangers of cold and hot sources;

III. Installation of the developed unit at any type of building - heating pump installation is common in buildings with a high latent charge on the inside, as the example of Covered Pools. The heating pump has a good performance merely in these cases despite not being the most convenient, in terms of power;

IV. Good operation during the insufflation of 100% Fresh Air - one of the major problems of dehumidifying heating pumps occurs during insufflation of 100% fresh air, because these don't have a good operation on relatively low external enthalpies;

V. Cooling Capacity for fresh or vitiated air - the dehumidifying heating pumps are not capable to cool the air that circulates in the air treatment unit. The system implies a subsequent heating of the air that exits the dehumidifying heating pump's evaporator; VI. Good operation of the dehumidifying heating pump, operating with the recirculated air in the installation - on Covered Pools, this feature may be harmful to the quality of interior air due to odour concentration in the air and the problem of Legionella in certain buildings. Brief Description of the Drawings

[6] Figure I shows an air treatment unit with interior humidity and temperature control of buildings such as Hospitals, Auditoriums, storage buildings for edible products, and other buildings with humidity control inside (the humidifier (20) may or not be necessary, depending on interior and exterior conditions of the building).

[7] Figure II shows an Air Treatment Unit with humidity and temperature control for a

Covered Pool's type (without humidifier).

[8] Figure III shows an operating scheme of the developed air treatment unit during the insufflation and heating of 100% fresh air without humidification, and the dehumidi- fication and heating steps of 100% fresh air. In the case of insufflation and heating of 100% fresh air, the heat exchanger of cool source (12) is inactive, while in the dehu- midification and heating of 100% fresh air this starts its working operation (ex. Covered Pools). The mixer (11) does not allow the fusion of fresh air with the vitiated air present in the installation.

[9] Figure IV shows the evolution of the air conditions in the psychometric diagram for an insufflation and heating of 100% fresh air. As previously mentioned, the heat exchanger of cool source is inactive (ex. Covered Pools).

[10] Figure V shows the evolution of air conditions in the psychometric diagram, for a de- humidification and heating of 100% fresh air (ex. Covered Pools).

[11] Figure VI shows an operating scheme of the developed air treatment unit during the dehumidification and heating of the mixture of fresh air and vitiated air comprised in the installation (ex. Covered Pools). The deflectors of the mixer (11) alter their position in order to allow the mixture of fresh air and vitiated one.

[12] Figure VII shows the evolution of air conditions in the psychometric diagram, for a dehumidifying and heating situation of the mixture of fresh air and vitiated air (ex. Covered Pools).

[13] Figure VIII shows the operating scheme of the developed air treatment unit for a cooling of 100% fresh air situation. The heat exchanger of hot source (19) is inactive and there is no mixture between fresh air and vitiated air. There is a 'bypass' to the heat recuperator, to reduce the charge loss in the ventilation circuit, decreasing power requirements.

[14] Figure IX represents in a psychometric diagram the air evolution during a cooling period of 100% fresh air (ex. Covered Pools). [15] Figure X shows the evolution of air conditions in psychometric diagram, for a situation of mechanical ventilation of 100% fresh air without thermic treatment (ex. Covered Pools).

[16] Figure XI shows the operating mode of the developed air treatment unit applied to a covered pool accordingly to internal and external conditions of acclimatized space (I- Insufflation and Heating of 100% fresh air; II- Dehumidification and Heating of 100% fresh air; III- Dehumidification and Heating of the fresh air and vitiated air mixture; IV- Mechanical Ventilation; a- internal temperature of the space; b- absolute humidity for average operating temperature of the heat exchanger of cool source; c- absolute humidity for inner conditions).

[17] The figure XII shows the operating mode of the developed air treatment unit, applied to a common building with humidity and temperature control, accordingly to internal and external conditions of the acclimatized space (I- Insufflation of 100% fresh air and heating/cooling with humidification of the air; II- Insufflation of 100% of fresh air with dehumidification and heating; III- Dehumidification and Heating of the fresh air and vitiated air mixture; a) Insufflation's Absolute Humidity; b- Enthalpy's line for interior conditions; c- Interior Conditions' point of the acclimatized space). Summary of the Invention

[18] The developed ATU comprises the heat recuperator (13) between the two heat exchangers- cold (cold water from the Chiller) and hot (hot water from the boiler) - promoting the thermic energy's exchange between the two air flows (building extraction and insufflation).

[19] The heat exchanger of cool source (12) undertakes the task to cool and dehumidify the insufflated air (fresh or vitiated air).

[20] The heat exchanger of hot source (19) allows the air heating up to the insufflation's temperature of the space to acclimatize.

[21] The mixer (11) allows the mixture of fresh with vitiated air in the installation, whenever convenient, in energetic terms or in interior air quality terms.

[22] The ventilators (14 and 21) allow the air circulation inside ventilation conducts of the building and at the developed air treatment unit, overcoming the power loss in the circuit.

[23] The heat recuperator (13) allows the thermic energy's exchange between the extract air and the insufflation's air of the building. This is placed between the exchangers of hot source (19) and cool source (12), increasing the number of hours of useful work.

[24] The acoustic attenuators (15 and 22) decrease the sent out pressure by ventilators in order to avoid its propagation along the installation.

[25] The filter on the fresh air inlet (10) has the purpose to retain the solid particles coming from the exterior air improving the air quality and reducing the chances of possible damage of the air treatment unit. In spite of this, another filter at the vitiated air inlet might be privided, removing some solid particles coming from the interior of the space to acclimatize. [26] The anti-vibrating bands or water-pouts (16 and 23) have the task not to propagate of vibrations to air conducts, lodged at the interior of the buildings, avoiding thus some undesirable noises. [27] The registers (17 and 18) are aimed to open/close the fresh air or vitiated air in the developed air treatment unit. [28] The humidificator (20) has the finality of adding water to the insufflation's air, for an increase in humidity's index. This may or not be useful, concerning the interior or exterior conditions of the space to acclimatize, and in such cases the developed ATU is set up as in Figure I. [29] Given the advantages of the developed unit for buildings with humidity control, then unit one is provided with an autonomous control in order to fit in the interior and exterior conditions of the building. This type of control allows the following operation modes:

I. Air Heatin with/without humidification - the ventilation system insufflates the necessary flow rate for the removal of the latent and sensible charge, and guarantees the interior air quality. The heat recuperator (13) will reduce the power consumption on the hot source (19) and the installed potency. Should a 100%-insufflation of fresh air occur and if the absolute humidity is inferior to insufflation values, there is a humidifier (20) that transfers water into the air. The air treatment unit is capable to regulate the absolute insufflation humidity by balancing the ventilation by balancing the ventilation flow rates, comparing the absolute humidity of the interior with the outdoor space, always guaranteeing the interior air quality by means of the mixture of fresh air and vitiated air. Figures III and IV show this operating mode.

II. Dehumidification and Heating of 100% of fresh air - procedure occurs when the absolute humidity of the exterior air is superior to the absolute humidity for air insufflation's conditions. In terms of power energy, the exterior conditions must present enthalpy values inferior to the interior air values. The heat recuperator (13) allows heat exchanges between air flows at the cold source exchanger outlet(12), and of the extract air of the building (Figure III and V).

III. Dehumidification and Heating of 100% of Recirculated Air at the installation - this operating mode occurs when the absolute humidity of exterior air is superior to the interior conditions'. In terms of energy, the exterior conditions must present enthalpy values superior to the interior values. The heat recuperator (13) allows the reduction of installed potency on heat exchangers of the hot source (19) and the cold source (12), as well as the reduction of energy consumption of these equipments. In terms of ventilation, this is the only situation in which a mixture of fresh air and recirculated air occurs in the Air Treatment Unit (ATU), requiring some care in terms of interior air quality (Figure VI and VII).

IV. Cooling of the Air with/without humidification - the ventilation system insufflates the necessary flow rate for the removal of charges (latent and sensible), guaranteeing interior air quality. This occurs when the absolute humidity of insufflation is superior to the absolute humidity of exterior air, being the humidification of the air necessary. The air treatment unit is also capable of regulating the insufflation's absolute humidity by means of balancing the ventilation flow rates, comparing the absolute humidity of the space with the exterior humidity, always guaranteeing interior air quality. In this situation, the heat recuperator (13) doesn't work, making a 'bypass' to this equipment. Figures VIII and IX present the unit's operating mode for this situation.

V. Mechanic Ventilation of the space - this situation may or not substitute operating periods in dehumidification and heating of recirculated air in the developed ATU. It can be implemented on Covered Pools in the Summer with high temperatures, transforming them into exterior pools. The advantage is that there is no energy consumption of neither on the hot source (19) nor on the cold source (12). In order to reduce ventilation requirements, there is a 'bypass' for the heat recuperator (13) decreasing the charge loss in the ventilation circuit (Figures VIII and X). Detailed Description of the Invention

[30] The developed Air Treatment Unit has the purpose to treat the building's interior air in terms of temperature and interior humidity.

[31] Buildings are liable to latent and sensible charges. The latent charges interfere on the humidity's index inside the space, while the sensible charge interferes on the temperature of the space to acclimatize. Covered pools are a good example of buildings with a high latent charge due to water evaporation. Other buildings, such as hospitals, present higher sensible charges than latent ones being the latent charges greatly due to inhabitation of the building.

[32] Buildings with humidity control present the highest power consumption.

[33] This developed air treatment unit was conceived to reduce these energy consumption due to a heat recuperator established inside the ATU.

[34] The materials that constitute the plate heat recuperator as well as the heat exchangers must present good features in terms of thermic conductivity and resistance to deterioration. The most common materials are copper and aluminium alloys, and the application of stainless steel in covered pools due to the existence of chlorine elements in the interior space. There are other types of heat recuperators that use two heat exchangers and exchange energy between the two air flows by means of an independent circuit of gas or water, these ones. [35] Nowadays it is common to install a heat recuperator at the external part of the unit, exchanging energy between the inlet fresh air and the exhaust air. However, this disposition is not the most favourable for the air treatment of a building with humidity control.

[36] In this manner, the energetically efficient air treatment, dehumidification and heating unit reduces significatively the power consumption by altering the localization of the heat recuperator, and by suitable control that alters its operating mode concerning the interior and exterior of the acclimatized space.

[37] The control of the air treatment unit is an important factor in the decrease of power consumption, and so being it should be endowed with temperature and humidity sensors, and a CO₂ sensor at the building's extract air conduct so as to regulate the fresh air flow rate according to the occupation of the space.

[38] By means of the interior and exterior condition's temperature reading, it will be possible to know the necessary flow rate for the removal of the sensible charge according to insufflation's temperature or vice- versa, that is to say, to know the insufflation's temperature for certain ventilation caudal.

[39] By means of the reading of the humidity in interior and exterior conditions, it will be possible to know the recirculated air's flow rate at the air treatment unit so as to remove the latent charge of the space according to the operating mode of the unit.

[40] By means of the CO₂ index reading, it will be possible to regulate register of fresh air inside the mixer so as to increase the fresh air's flow rate to insufflate inside the building, so that by one's turn it could dilute the concentrations of this element generated by the occupation of the building.

[41] When this unit is installed at covered pools it needs a reading sensor for chlorine concentrations, at the extract conduct of interior air, which will proceed with the register of fresh air.

[42] The ventilation's flow rate is determined by the unit's operating mode, and by the temperature's lecture and humidity's index of interior and exterior conditions of the building.

[43] Concerning the operating mode, the developed air treatment unit, by reading the exterior temperature, will draw a comparison with interior temperature and with the absolute humidity of insufflation air. It is necessary to pay attention to the operating temperatures of the 'Chiller', because it is the limit of dew's temperature for the minimum absolute humidity of insufflation conditions.

[44] In case of exterior conditions being with a dry temperature's bulb inferior to the interior temperature, and a specific humidity inferior to the specific humidity for medium temperature (of dew) of Chiller's operation (operating mode I of an ATU for a covered pool), the air treatment unit will insufflate 100% of fresh air and will bring into action the hot source (piece 19 of figure I). The heat recuperator (piece 13 of figure I) will reduce the heating necessities through the thermic energy's exchange between the extract air and the insufflation air at the entry of the hot source, decreasing the installed potency at the heat exchanger. In case of absolute humidity of exterior conditions being inferior to the insufflation conditions, it will be necessary the installation of a humidificator (piece 20 of figure I). The system's control may be capable of mixing the fresh air with the recirculated air in order to reach the absolute insufflation humidity. Briefly, the heat recuperator will spare energy since the point c=d=e till point f of figure IV, that would be necessary to spend by the heat exchanger of hot source.

[45] If exterior conditions present a dry temperature's bulb inferior to the interior temperature, and a specific humidity superior to the specific humidity for medium temperature (of dew) of Chiller's working, and inferior to the absolute humidity for the interior conditions, being at zone II of figure VI (operating procedure of the ATU for a covered pool), the air treatment unit will dehumidificate and heat 100% of fresh air and will bring into action the hot and cold sources (pieces 19 and 12 respectively, of figure I). The exterior air, presenting an absolute humidity superior to insufflation conditions, will bring into action the cold source dehumidificationing the fresh air. This fresh air, when enters into the heat recuperator (piece 13 of figure I), will exchange thermic energy with the extract air that will cross immediately at the hot source's exchanger. In terms of reducing energy, the heat recuperator helps at the decreasing of heating's energy since point e till point f of figure V.

[46] Supposing, that the exterior point has a dry bulb's temperature inferior to the interior temperature, and with a specific humidity superior to the interior conditions being at zone III of figure XI (way of working III of the ATU for a covered pool). In this manner, the air treatment unit will mix the fresh air with the recirculated air at piece II of figure I (the flow rate to insufflate fresh air will be determined by the CO₂ concentration index reading, and by the concentration index of any polluter therein generated: for example - chlorine concentrations in covered pools). After being mixed (point d of figure VII), this will cross the cold source (piece 12 of figure 1). In this case, the heat recuperator is reducing the cooling necessities, because instead of cooling the air since point c till point e of figure VII (dehumidification and heating of 100% of fresh air) or since the point of the mixture of fresh air with the extract air till the point of figure VII (dehumidification and heating of the mixture of fresh air with recirculated one), this heat recuperator will cool since point d to point e of figure VII. In spite of all this being described in terms of cooling, the same may occur in case of heating because it's possible to reduce power necessities from point e to point f of figure VII. [47] In case of the exterior point being with a dry bulb's temperature superior to the interior conditions, and being at zone IV of figure XI, the developed air treatment unit will bring into action only the ventilators (14 and 21). Thus, the covered pool will be transformed into an exterior pool, not being necessary the air treatment for exterior temperatures superiors to interior temperature. The temperature and interior humidity is not controlled anymore.

[48] For situations in which exterior absolute humidity is inferior to the insufflation humidity, and the exterior temperature is superior to interior one (operating mode IV of the ATU for a covered pool), the developed air treatment unit will insufflate 100% of fresh air bringing into action the heat exchanger of cold source. The exterior air, crossing through the cold source (12) cools (sensible cooling), and immediately does the bypass to the heat recuperator as it is presented in figure IX.

[49] The previous operating procedures are destined for applications at covered pools.

Moreover, this unit can also be installed in other buildings with humidity and interior temperature control. For such it is necessary to alter the control of the unit as it is presented at figure XII (I- Insufflation of 100% fresh air, with Heating or Cooling, and humidification of exterior's air till the reachment of insufflation conditions; II- Insufflation of 100% fresh air, with Dehumidification and Heating; III- Dehumidification and Heating of the mixture of fresh air and vitiated air from the installation; a) Absolute Humidity of insufflation air; b) Enthalpy line for interior conditions of the building; c) Interior conditions' point of acclimatized space).

Claims

[1] Air Treatment Unit energetically efficient of dehumidification and heating and use thereof, comprising:

- an inlet for exterior air with a registry section (17) followed by an air filter (10), a mixer (11) and an exchanger of cold source (12);

- a return inlet for the building's interior air with an anti- vibrating band or flow rate (16) followed by an acoustic attenuator (15), and a ventilator (14);

- an outlet for insufflation air to the building's interior with anti-vibrating band or sleeve (23) followed by an acoustic attenuator (22), a ventilator (21), a humidifier (20) and an exchanger of hot source (19);

- an outlet for exhaust air with a registry section (18);

- a heat recuperator that promotes the exchange of thermic energy between the extract air and the insufflation's one, which receives the air from the inlet for interior air and from the return inlet for interior air, providing air to insufflation's air exit and to exhaustion's air exit;

- a heat recuperator (13) that is contained between two exchangers of hot source (19) and cold source (12), the heat recuperator and heat exchangers are structured by allows of copper, aluminium and inox steel.

[2] Air Treatment Unit according to claim I, characterized in that it operates as a conventional heating unit with heat recuperation or air cooling which circulates in the interior.

[3] Air Treatment Unit according to claims 1 and 2, characterized in that the heat exchanger of cold source (12) is connected to a Chiller dimensioned for the maximum charge of the building or with a reservoir of cold water storage, which hot exchanger of cold source (12) is responsible for dehumidification or cooling of the air that circulates at the installation.

[4] Air Treatment Unit according to claims 1 to 3, characterized in that the heat exchanger of hot source (19) is connected to a boiler dimensioned for the maximum charge of the building or a reservoir of hot water storage.

[5] Air Treatment Unit according to claims 1 to 4, comprising a control system capable to sustain the following operating procedures to the developed air treatment unit, in a space to acclimatize with humidity control:- Heating of 100% fresh air with or without humidification; dehumidification and heating of 100% fresh air; dehumidification and heating of the mixture of fresh air and vitiated air coming from the installation; cooling of 100% fresh air with or without humidification- and for spaces to acclimatize without humidity control:- Heating of the mixture of fresh air and vitiated air, and mechanic ventilation without thermic treatment of the air, concerning the interior and exterior conditions of the space. [6] Air Treatment Unit according to claims 1 to 5, comprising a rotative heat recuperator (13) or plate heat recuperator, for the exchange of thermic energy between the two air flows.

[7] Air Treatment Unit according to claims 1 to 6, comprising ventilators for the circulation of the necessary flow rate for the removal of the building's thermic energy, overcoming the charge loss at the ventilation circuit. [8] Air Treatment Unit according to claims 1 to 7, comprising a mixer (11) for the mixture of fresh air and vitiated air. [9] Air treatment unit according to claims 1 to 8, comprising air filters to retain solid particles coming from the interior and exterior environments. [10] Air Treatment Unit according to claims 1 to 9, comprising acoustic attenuators, to avoid the propagation of sound pressure due to ventilators' working. [11] Air Treatment Unit according to claims 1 to 10, comprising anti-vibrating bands to avoid the propagation of vibrations to the interior conducts of the building. [12] Air Treatment Unit according to claim 5 (on covered pools), comprising an air treatment controller that includes: temperature sensors to know the necessary flow rate for the removal of the sensible charge according to insufflation temperature or to know the insufflation temperature for certain ventilation flow rate; humidity sensors to know the recirculated air flow rate at the air treatment unit so as to remove the latent charge of the space according to the operating mode of the unit; a CO₂ sensor, at the extract air conduct of the building, to regulate the fresh air flow rate according to the inhabitance of the building; a reading sensor, of the chlorine concentrations at the extract conduct for the interior air, to act as a register of fresh air. [13] Air Treatment Unit according to claim 5, characterized in that it is capable to sustain the following operating modes (covered polls), when the exterior air has a dry bulb's temperature inferior to the absolute humidity for the Chiller's operation mode (temperature of dew - operation mode I of the ATU); the air treatment unit insufflates 100% fresh air and activates the hot source

(19); the heat recuperator (13) reduces the heat necessities through the exchange of thermic energy between extract air and the insufflation air at the inlet of hot source; if the absolute humidity of exterior air is inferior to the one of the in- sufflation air, the humidifier (20) is activated; the mixture of fresh air and recirculated air, to obtain absolute humidity of insufflation. [14] Air treatment unit according to claim 5, characterized in that it is capable to provide the following operating mode (on Covered Pools), when exterior air has a dry bulb's temperature inferior to the interior temperature, and the exterior Specific Humidity is between the absolute humidity, for the Chiller's operating mode, and inferior to absolute humidity for interior conditions (operating mode II): the Air Treatment Unit dehumidificates and heats 100% fresh air and activates the hot and cold sources (19) and (12); if the exterior air presents an absolute humidity superior to the insufflation conditions, the cold source is activated thus dehumidifying the fresh air that enters into the heat recuperator (13); the heat recuperator (13) exchanges thermic energy with extract air, which soon after passes through the hot source's exchanger. [15] Air Treatment Unit according to claim 5, characterized in that it is capable to improve the following operating mode (for Covered Pools), when exterior air has a dry bulb's temperature inferior to the interior temperature, and the Specific Humidity is superior to the absolute humidity for interior conditions (way of working III): the Air Treatment Unit dehumidifies and heats the recirculated air when absolute humidity of exterior air is superior to the interior air; the fresh air is mixed with recirculated air in piece 11 and after being mixed passes through the cold source (12); it proceeds to the heat recuperator which decreases the cooling potencies of hot and cold sources. [16] Air Treatment Unit according to claim 5, characterized in that it is capable to improve the following operating mode (for Covered Pools), when exterior air has a dry bulb's temperature superior to the interior temperature: the developed Air Treatment Unit activates the ventilators (14) and (21); for air conditions with exterior temperatures superior to the interior temperature, and when exterior absolute humidity is superior to the insufflation humidity, the temperature and interior humidity stop being controlled; for air conditions with exterior temperatures superior to the interior temperature, and the exterior absolute humidity being inferior to the insufflation humifity, the developed air treatment unit will insufflate 100% fresh air activating the heat exchanger of cold source wherein exterior air passes through the cold source (12), cools (sensible cooling), and soon after makes a bypass to the heat recuperator.

[17] Air Treatment Unit according to claim 5, characterized in that it is capable to improve the following operating modes, for any type of building with humidity and temperature control inside it, wherein when the exterior air is: below line (a) of absolute humidity of insufflation air, the unit improves mode r - Insufflation of 100% Fresh Air, with Heating or Cooling and Hu- midification of exterior air till insufflation conditions are obtained; above line (a) of absolute humidity of insufflation air and below line (b) of enthalpy for interior conditions of the building (that contains point (c) of interior conditions of the acclimatized space), the unit improves mode IF - Insufflation of 100% Fresh Air, with dehumidification and Heating; above line (a) of absolute humidity of insufflation air and above line (b) of enthalpy for interior conditions of the building (that contains point (c) of interior conditions of the acclimatized space), the unit improves mode IH' - Dehumidification and Heating of the mixture of fresh air and vitiated air coming from the installation.