CABIN THERMAL CONTROL SYSTEM

Abstract

The present finding relates to a system for controlling a cabin at least thermally. The system (10) with energy recovery includes a first air treatment unit (20) suitable to collect external air and supplying air at least thermally controlled (air treated) in the cabin (12), a second air treatment unit (30) suitable to collect exhausted air from the cabin (12) and heat exchange means (43) configured to exchange heat between exhausted air and external cabin air supply. The system also includes air humidification means (45) suitable to humidify the exhausted air, to reduce, using evaporation enthalpy, the preset temperature of the exhausted air, and to supply the exhausted humidified air to the heat exchange means in order to optimize the recovery of energy. The finding also relates to an exhausted air treatment unit and to a method to control a cabin at least thermally.

Description

FIELD OF THE INVENTION

This invention relates broadly to a cabin thermal control system with energy recovery.

More particularly, this invention relates to thermohygrometric cabin control systems for painting cabins, surface preparation cabins, clean rooms, etc.

STATE OF THE ART

Energy recovery systems to thermally or hygrometrically control various types of cabins, such as painting cabins are known. These systems include, generally, a first air treatment unit (first ATU) to supply external air to the cabin and a second air treatment unit (second ATU) to extract exhausted air from the cabin. For example it is known that in thermohygrometric cabin control systems, which here are taken as reference for ease of description, the first ATU includes:

• • an air ventilation section in the cabin to external air into the cabin;
  • a heating section to heat air, if required;
  • a cooling section to cool air, this section may be used also to obtain the condensation and collection of water and therefore to dehumidify the air;
  • a humidification section, to humidify the air and at a predefined humidity level;
  • a post-heating section to cooperate with the humidification section to allow the inlet of
    air with a predefined temperature and humidity level into the cabin; and that the second ATU includes, for example:
  • a cabin air extraction ventilation section to extract the exhausted air from the cabin;
  • a cross-flow or rotating flow heat exchanger section to exchange heat between the exhausted air and the external air to supply to the cabin in order to obtain energy recovery from this exchange of heat.

The Requester has observed that the recovery of energy for simple cross-flow of air into and out of the cabin is extremely low and that, therefore, cabin energy recovery systems should be improved in order to obtain a significantly better recovery.

In summary the Requester has observed that solving the technical problem of energy recovery optimization in cabin systems seems to be an urgent issue.

DESCRIPTION OF THE INVENTION

This invention aims at solving the above mentioned issue with cabin energy recovery systems.

This technical problem is solved with the cabin thermal control system as claimed.

This invention relates also to a method to recover energy in a cabin thermal control system.

The claims comprise an integral part of the technical knowledge supplied here about this invention.

According to a preferred form of execution, the system to control a cabin at least thermally

includes upstream of a heat exchanger section that exchanges heat between exhausted air extracted from the cabin and external air to supply to the cabin, an air humidification unit to lower the temperature of the exhausted air and thus optimize the recovery of energy obtainable from the heat exchanger system.

According to a further characteristic of this invention, the method to control a cabin at least thermally associates the phase of collection from the cabin of exhausted air with a phase of humidification of the exhausted air in order to reduce, through evaporation enthalpy, the temperature of the exhausted air and optimize the system's energy recovery.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of this invention will become clear from the following description of a preferred production form, as a non-exhaustive example with the help of drawings, in which the elements indicated with a same or similar numerical reference indicate components with the same or similar function and structure, and in which:

FIG. 1 Represents a block chart of the system according to the invention.

DESCRIPTION OF A PREFERRED FORM OF EXECUTION

With reference to FIG. 1, a system 10 to control at least thermally a cabin 12, according to this invention, includes, upstream of the cabin, a first air treatment unit (first ATU) 20 and downstream of the cabin a second air treatment unit (second ATU) 30.

The first ATU 20, of known type, collects external air and lets air at a controlled temperature and, according to this example, humidity (treated air), into cabin 12 and includes, as an example, an air inlet ventilation section in cabin 20a, a heating section 20b, a cooling section 20c, a humidification section 20d and a post-heating section 20e, all of known type and connected between them in a known manner. According to the preferred form of execution, the first ATU 20 has an air inlet conduit 21, connected to an air outlet of the second ATU 30 and allows the collection of external air, and at least one air inlet conduit 23 connected to cabin 12 to supply treated air to cabin 12.

The second ATU 30 extracts the air from cabin 12 and treats it in order to recover, in an optimized way, energy useful to treat the air with the first ATU 20, as will be described below in detail.

It should be noted that in the description of system 10 according to this invention, the configured sections are particularly taken into account to obtain the cooling of the external air inlet into the cabin, as the invention has been developed to optimize the recovery of energy in said conditions, i.e., when the temperature of the air supplied from the outside is higher than the temperature of the air expected in the cabin and therefore the temperature of the air supplied to the cabin must be reduced significantly to preset values.

The second ATU 30, according to the preferred form of execution, includes:

• • a section or extracted air treatment means 41, of known type, to extract air from cabin 12 through an air extraction conduit 31 and filter it; this section may include on the outlet, an air recirculation conduit 33, per se known, connected to conduit 21, if air recirculation is present;
  • a heat exchanger section or heat exchange means 43, e.g., across-flow or rotating section, of known type, e.g., a NOVAIR-CLINT model section RF14/3730/S/AL; the heat exchanger section 43 is connected to the first ATU 20 through a conduit 21 and includes an external air inlet conduit 37 connected to an external air intake 47a, with interposed, preferably, a filtering section 47, an outlet conduit 39 suitable to discharge exhausted air outside with interposed, preferably, an emission system or treatment section 49, of known type, suitable to filter/eliminate polluting substances present in the exhausted air;

Further, the second ATU 30, according to one of the characteristics of this invention, includes the following:

• • a section or humidification means 45, having an exhausted air inlet conduit 34 connected to the section of extracted air treatment 41 and a humidified exhausted air outlet conduit 35 connected to the heat exchanger section 43.

The humidification section 45, e.g., a NOVAIR-CLINT ADIABATIC SECTION 200 mm model section is suited to humidify the exhausted air out of the cabin, thanks to simple water evaporation and using evaporation enthalpy, and is suited to noticeably lower, as will become clear later,

the temperature of the exhausted air extracted from cabin 12 before being supplied to the second heat exchanger section 43.

It should be noted that in this description, as can be easily understood by a technician of the field, the term conduit is used in a broad sense to indicate one or more conduits or tubes suited to transport fluids, e.g., air.

It should also be added that in this description two air treatment units (ATU) have been defined, for ease of description, but that, as can be easily understood by a technician of the field, the sections described may be independent sections connected between them to execute the system without requiring inclusion in corresponding air treatment units.

The system 10 described so far works as follows.

The air from the environment is pre-filtered into filter section 47 to then go through heat exchanger section 43, crossing the exhausted air extracted from the cabin.

Once the air has passed through the heat exchanger section 43, it is extracted from the first ATU 20 in which its thermohygrometric control occurs.

The air is supplied to cabin 12 to maintain preset thermohygrometric conditions in the cabin.

The extracted air treatment section 41 extracts “exhausted” air from cabin 12 to supply to humidification section 45 and/or partially recirculate it in the first ATU 20 through conduit 33.

The recirculation depends on possible air pollution occurred during manufacturing processes within cabin 12 and, according to execution variations of this invention, may not be present.

The air not recirculated is treated by humidification section 45, cooled further and with a higher specific heat (SH), due to water evaporation, is sent to the heat exchanger section 43 to then be discharged into the environment or sent to an exhausted air treatment system 49 through conduit 39.

The results of energy recovery are reported below following trial tests conducted with the system according to the invention, from which it can be inferred that the presence of humidification section 45 enables the highest energy recovery for system 10.

A cabin that operates for 16 hours daily with the following should be taken as reference:

• • 85,000 m3/h air capacity (at 25° C. internal cabin conditions);
  • a cabin environment temperature of 25° C.;
  • a cabin environment relative humidity (RH) of 50+5% RH.

Summer conditions with a temperature of 35° C. and 50% RH should be assumed.

System without Humidification Section

The cross-flow heat exchanger section has:

• • cabin extraction airflow 77,872 Nm3/h corresponding to 85,000 m3/h at 25° C.
  • Temperature 25° C.;
  • Relative humidity 50±5%;
  • Cabin inlet airflow 77,872 Nm3/h, corresponding to 87,850 m3/h at 35° C.;
  • Temperature 25° C.;
  • Relative humidity 50±5%;

Considering an average of 60% efficiency for the heat exchanger, energy recovery is approximately 147,393 kCal/h, with a thermal differential of approximately 6° C. That is, the inlet air is cooled by 6° C., then an inlet air cooling is obtained from 35° C. to 29° C.

System with Humidification Section

If there is a humidification section, the exhausted extraction air is humidified before going through the cross-flow exchanger.

In the assumed conditions, the humidification section may cool the air from 25° C. with RH=50%, to approximately 21° C. with RH=70%.

In this case, in the cross-flow exchanger, the following operating conditions occur:

• • Cabin extraction airflow 77,872 Nm3/h corresponding to 85,000 m3/h at 25° C.;
  • Temperature 21° C.;
  • Relative humidity approximately 70%;
  • Cabin inlet airflow 77,872 Nm3/h
    corresponding to 87,850 m3/h at 35° C.;
  • Temperature 25° C.;
  • Relative humidity 50±5%;

Considering an average of 60% efficiency for the heat exchanger, energy recovery is approximately 206,350 kCal/h with a thermal differential of approximately 8.4° C. The inlet air is cooled by 8.4° C., so it would then cool from 35° C. to 26.6° C.

The increase in energy recovery is significant and corresponds to approximately 40% in these operating conditions.

Therefore, while the annual energy recovery with cross-flow only in the example is approximately:

• Hourly recovery=171.3 kW;
• Daily recovery=2,740.8 kW.

If the system and the humidification section according to the invention are used, the recovery in electric kW (kW) of approximately 913.6 kW corresponding to an energy recovery with cross-flow and humidification as follows:

• Hourly recovery=239.8 kW;
• Daily recovery 3,836.8 kW;
• Yearly electrical kW recovery of 1278.9 kW.

Therefore, it becomes evident from the example that the introduction of a section of humidification in the treatment of exhausted air increases considerably, at the same conditions, the volume of thermal recovery.

The system, as described, applies to thermally or thermohygrometrically control painting cabins, surface preparation cabins, clean rooms and special cabins, and aims at improving energy recovery by humidifying the extraction air before treating it with a heat exchanger, e.g., a cross-flow or rotating type.

Obvious changes or variants may be made to the above description, in sizes, shapes, materials, components and connections, as in the details of the illustrated execution and of the operating method without departing from the spirit of the invention, as noted in the following claims.

Claims

1. System to control a cabin, at least thermally including

a first air treatment unit (20) suitable to collect external air, treat external air and supply to the cabin (12) at least thermally controlled;

a second air treatment unit (30) suitable to extract from the cabin exhausted air at a set temperature;

heat exchange means (43) configured to exchange heat between the exhausted air and external air as it is collected; characterized by whether second air treatment unit (30) includes

air humidification means (45) suitable to humidify exhausted air, to reduce, using evaporation enthalpy, the temperature of said exhausted air and supply to exhausted air humidified in said heat exchange means.

2. System according to claim 1 characterized by whether said heat exchange means (43) are included in said second air treatment unit (30).

3. System according to claim 1 characterized by whether said second air treatment unit (30) includes further

extraction air treatment means (41) suitable to extract the exhausted air, filter it and supply it to said air humidification means.

4. System according to claim 1 characterized by whether said first air treatment unit (20) includes

at least a cooling section (20c) suitable to cool the air coming from said heat exchange means.

5. System according the claim 4 characterized by whether said first air treatment unit (20) includes at least a section included in the group of

a ventilation section (20a);

an air heating section (20b);

a humidification section (20d);

an air post-heating section (20e);

6. System according to claim 1 characterized by the fact that it includes an external air filtering section (47) suitable to filter the external air to supply to the cabin (12) through the first air treatment unit and/or an exhausted air filtering section (49) suitable to filter the humidified exhausted air employed by said heat exchange means (43) and to discharge the humidified exhausted air outside the cabin.

7. Exhausted air treatment unit for a system to control at least thermally a cabin, including

air treatment means (41) which may be connected to the cabin and are suitable to extract exhausted air at a preset temperature;

heat exchange means (43) configured to exchange heat between exhausted air and external air; characterized by

air humidification means (45) suitable to humidify said exhausted air, to reduce, using evaporation enthalpy, the temperature of said exhausted air and supply to the humidified exhausted air into said heat exchange means (43).

8. Exhausted air treatment unit, according to claim 7, characterized by whether said heat exchange means (43) are of the cross-flow or rotating type.

9. Method to control at least thermally a cabin, including the following phases: characterized by the fact that the exhausted air collection phase includes the phase of

collect external air;

treat at least thermally said external air and supply, following treatment, air at least thermally controlled to the cabin;

collect from the cabin exhausted air at a preset temperature;

perform a heat exchange between the exhausted air and the external air;

humidification of the exhausted air so as to reduce, using evaporation enthalpy, the preset temperature of said exhausted air.

10. Method according to claim 9 characterized by the fact that the exhausted air collection phase further includes the phase of

filtering said exhausted air.

11. Method according to claim 9 characterized by the fact that said phase of treating at least thermally said external air includes the phase of

cooling the air before supplying it to said cabin.

12. Method according to claim 9 characterized by the fact that it also includes at least one of the phases of

filtering the external air to supply to the cabin; and/or

filtering the humidified exhausted air and discharging it outside the cabin.