EP4644795A1

EP4644795A1 - Highly energy-efficient climate control system for buildings that includes an inlet for suction airflow from the outside and an outlet for treated supply airflow

Info

Publication number: EP4644795A1
Application number: EP24759812.1A
Authority: EP
Inventors: Rafael CRUZ MARZO
Original assignee: Zarraluqui Navarro Marta
Current assignee: Zarraluqui Navarro Marta
Priority date: 2023-02-22
Filing date: 2024-02-16
Publication date: 2025-11-05
Also published as: MX2025009880A; ES2979381A1; ES2979381B2; WO2024175816A1

Abstract

The present invention discloses an air conditioning system that incorporates a compact and autonomous unit capable of providing very high indoor air quality with significantly elevated energy efficiency. The system features a pre-cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (1) fed by water collected by a water pump (BAT1), an adiabatic exchange system (2), a water tank in the pre-cooling section (3) for unevaporated water, and a condenser coil from the direct expansion system (6); a cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (4), a direct thermodynamic exchange system (5) fed by a water pump (MED1); a cooling section water tank, and an evaporator coil from the direct expansion system (7); and a direct expansion system (8) installed in an adiabatic environment.

Description

OBJECT OF THE INVENTION

The present invention discloses an air conditioning system that incorporates a compact and autonomous unit capable of providing very high indoor air quality with significantly higher energy efficiency compared to current conventional air conditioning systems. It achieves this by lowering the dry temperature of outdoor air, ensuring complete renewal of indoor air without recirculation or depletion, providing optimal indoor relative humidity for health and comfort, and ionizing the indoor air.

BACKGROUND OF THE INVENTION

Human comfort and productivity require precise control of temperature and humidity. For centuries, fossil fuels have been used to provide heat, and in recent years, refrigeration equipment has been employed to transfer thermal energy through mechanical means involving compression and expansion of a working fluid for cooling and humidity control. It has been observed that most such refrigeration units use electricity as their main energy source. Indeed, the rapid increase in air conditioning capacity in recent years has placed nearly intolerable demands on public utility systems and similarly increased the demand for power plants and heat rejection facilities.
Air conditioning installations for modern buildings-such as large office buildings, shopping complexes, warehouses, and the like-typically comprise air handling units to which water or another heat exchange fluid is pumped. This fluid cools the air (in summer) or heats it (in winter) and is circulated to the conditioned areas. The heat exchange fluid used for cooling usually circulates through an evaporator/chiller of a refrigeration system that removes heat from the fluid. This heat is then transferred to a second heat exchange fluid circulating through the system's condenser. The second fluid may be water, another liquid, or air in evaporative or air-cooled systems. Such systems may also be designed to operate in reverse cycle mode as heat pumps. The refrigeration system must have adequate cooling/heating capacity for the installation. High-capacity installations, as used in office and apartment buildings, require high-performance refrigeration systems to handle peak loads.
To limit the space occupied in residential buildings by HVAC systems, it has become desirable to develop residential air conditioning systems that can also function as heating systems in winter, thus providing complete space conditioning in a single unit. These systems must be highly efficient to reduce energy consumption and significantly lower energy bills.
Patent application WO/2004/088219 discloses a system to improve the energy efficiency of a refrigeration cycle comprising: an auxiliary heat exchanger unit for exchanging heat between high-pressure refrigerant liquid and low-pressure refrigerant vapor; and a housing containing a pressure support valve placed at the inlet of an internal tube of the auxiliary heat exchanger unit. The pressure of the high-pressure refrigerant liquid condensed in the external heat exchanger is reduced by the pressure support valve while maintaining the condensation pressure of the external heat exchanger. This system may be used in conjunction with conventional air coolers and heat pumps.
Korean patent application KR100776371 discloses a high-efficiency refrigeration system for energy saving and a control method to operate a high-power-demand compressor at a low compression ratio by maximizing use of heat from a condenser, thereby improving compressor efficiency. A refrigerant liquid pressure control valve (101) controls a high-pressure refrigerant to the proposed refrigerant supply pressure for selecting the capacity of an expansion valve (8). A gas/liquid heat exchanger (102) eliminates flash gas generated by depressurizing the high-pressure liquid refrigerant from the pressure control valve and exchanges heat between low-temperature low-pressure refrigerant gas and refrigerant liquid.
The present invention surpasses the energy efficiency of known systems by utilizing water in combination with a direct expansion system to reduce the temperature of outdoor air with minimal electrical consumption. Simultaneously, it naturally humidifies the air due to the process. This system achieves high indoor air quality by influencing parameters such as reduction of the dry temperature of outdoor air, complete renewal of indoor air without recirculation or depletion, provision of optimal indoor relative humidity for health and comfort, ionization of indoor air, and removal of indoor pollutants by overpressure.
The invention features a direct expansion system installed in an adiabatic environment, where the evaporator and condenser coils never operate with air at outdoor temperatures, but at several degrees below due to the cooling of this air via its wet-bulb temperature depression. This significantly enhances the unit's thermodynamic performance by collecting water at progressively lower temperatures through a cascading process. As a result, it provides extremely high indoor air quality with substantially higher energy efficiency than current conventional air conditioning systems, all while ensuring complete renewal of indoor air and significantly reducing power consumption compared to existing systems.

DESCRIPTION

DESCRIPTION OF THE DRAWINGS

To complement the present description and to facilitate a better understanding of the features of the invention, according to a preferred embodiment thereof, a set of illustrative, non-limiting drawings is included:

FIG. 1 - Schematic view of the air conditioning system of the invention, showing arrows indicating suctioned outdoor air entering the system and arrows indicating supply air flow driven by the system. It shows a pre-cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (1), an adiabatic exchange system (2), and a condenser coil from the direct expansion system (6). Also shown is a cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (4), a direct thermodynamic exchange system (5), and an evaporator coil from the direct expansion system (7).
FIG. 2 - Perspective view of a preferred embodiment showing a pre-cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (1) fed by water collected by a water pump (BAT1), an adiabatic exchange system (2), a pre-cooling section water tank (3) for unevaporated water at or near outdoor wet-bulb temperature, in a first stage of the process, and fed through the same water pump (BAT1), and a condenser coil from the direct expansion system (6); a cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (4), a direct thermodynamic exchange system (5) fed by a water pump (MED1) delivering water from the pre-cooling tank (3), and an evaporator coil from the direct expansion system (7); and a direct expansion system (8) installed in an adiabatic environment, activated from the already reduced temperature range delivered by the adiabatic system (2), and from there to the temperature required to deliver air to the building interior.

PREFERRED EMBODIMENT OF THE INVENTION

The present invention discloses a direct expansion system composed of a unit installed in an adiabatic environment, where the evaporator coil and the condenser coil never suction air under outdoor temperature conditions, but do so at several degrees below as the outdoor air is cooled as many degrees as possible by the depression of its wet-bulb temperature. The technology used by the device is based on a "cascade" process of water and air cooling inside it, which takes place between a Pre-Cooling Section and a Cooling Section. The water temperature is progressively lowered to the different wet-bulb temperatures at which the air is suctioned in successive stages and processes, descending below the wet-bulb temperature of the air in each process. The air temperature is progressively lowered, assisted by the cooled water, either with or without enthalpy variation.
The system unit features a sophisticated sensorized control system that, depending on outdoor air conditions, the building's interior temperature, and the primary supply air temperature of the unit, operates in four levels of air cooling to achieve maximum energy efficiency: Ventilation, Indirect Cooling, Indirect/Direct, and Hybridization. In this case, the unit uses the direct expansion system operating as a heat pump, reversing the cycle as needed to provide hot or cold air. When supplying hot air, the Cooling Section recirculates part of the indoor air, and the Pre-Cooling Section recirculates the renewal indoor air, expelling it outside after recovering its energy in the corresponding direct expansion coil.
The high energy efficiency air conditioning system for buildings includes an inlet for suctioned outdoor air and an outlet for treated supply air. The system of the present invention comprises: a Pre-Cooling Section intended to cool water without mechanical compression to the different wet-bulb temperatures of the intake air. It also cools the condenser coil of the direct expansion system using the cold air resulting from the water cooling process. This Pre-Cooling Section includes a water-air thermodynamic exchange coil (1) fed by water collected by a pump (BAT1), an adiabatic exchange system (2), a water tank (3) for unevaporated water near the outdoor wet-bulb temperature, fed through said pump (BAT1), and a condenser coil of the direct expansion system (6).
The system also includes a Cooling Section intended to treat the primary air introduced into the building in successive stages of the air cooling process. It also serves to cool the water collected in tank (3) of the Pre-Cooling Section by a specific device, enhancing the thermodynamic performance of the unit by collecting progressively cooler water from each coil in a "cascade" process, which is then delivered by the pump in the Pre-Cooling Section to the water-air exchange coils (4), (1). The cold airflow from both Sections can be combined for indoor climate control under certain circumstances, often doubling the cooling capacity of the unit. The Cooling Section also includes a water-air thermodynamic exchange coil (4), a direct thermodynamic exchange system (5) fed by a water pump (MED1) drawing water from the pre-cooling tank (3), and an evaporator coil from the direct expansion system (7). This Section also pre-cools outdoor air before it reaches the evaporator coil, using a water pump that supplies the adiabatic exchange medium in this section.
The invention also features a Direct Expansion System (8) installed in an adiabatic environment and activated from the already reduced temperature level reached by the adiabatic system (2), and from there to the temperature required to deliver air to the interior of the building. The Direct Expansion System (8) only operates when the temperature demand inside the building is such that the outdoor air's wet-bulb temperature depression does not suffice, and it does so only from the already reduced temperature level, not from the outdoor dry air temperature, to the required supply temperature.
The air cooling process, as previously described, uses water cooled to various wet-bulb temperatures through the cascading process designed by the invention.
In a first stage of the process, the Direct Expansion System (8) does not operate, and outdoor air is suctioned by the Pre-Cooling Section after being filtered. It passes through a water-air thermodynamic exchange coil (1), fed by water collected by pump (BAT1) from the strategically placed water tank (3). Thus, the filtered outdoor air passes through this water-air exchange coil (1) and is pre-cooled with enthalpy variation approaching the outdoor wet-bulb temperature. Once the outdoor air is pre-cooled without using refrigerant gases and with reduced dry and wet temperatures, it passes through a thermodynamic exchange system (2), this time adiabatic, and is further cooled without enthalpy variation, while being ionized and humidified. Water that has not evaporated and is close to the outdoor wet-bulb temperature is collected in tank (3) and, through pump (BAT1), fed to both water-air exchange coils (1), (4) and the adiabatic thermodynamic exchange medium (2) in the Pre-Cooling Section.
Therefore, pump (BAT1) delivers water cooled to the outdoor wet-bulb temperature to the water-air thermodynamic exchange coil (4) in the Cooling Section. Outdoor air, previously filtered, passes through coil (4) where it is cooled with enthalpy variation. It then passes through a direct thermodynamic exchange medium (5), fed by pump (MED1) drawing from tank (3), where it is further cooled without enthalpy variation. At this point, the air's dry and wet temperatures have been reduced below those of the outdoor air without using a direct expansion system.
Water not evaporated in exchange system (5), now at a temperature lower than that of the outdoor humid air, is collected in tank (3), from which it is drawn by pump (BAT1) to feed the hydraulic circuit: first both water-air exchange coils (1), (4) in the Pre-Cooling and Cooling Sections independently and simultaneously, and later, once warmed, to the adiabatic exchange medium in the Pre-Cooling Section.
This process is repeated continuously in a cascading fashion until the supply air temperature in the Cooling Section reaches or even falls below the wet-bulb temperature of the air as treated by indirect coil (4).
Once this occurs and air is delivered by the Cooling Section at the wet-bulb temperature from coil (4), a second stage begins with the operation of the direct expansion system in the unit:
Outdoor air is again suctioned by the Pre-Cooling Section after filtering and passes through the water-air thermodynamic exchange coil (1) as described in the first stage. This coil is now fed with water from tank (3) at a temperature significantly lower than the outdoor wet-bulb temperature. The filtered air passes through coil (1), where it is again pre-cooled with enthalpy variation, this time close to the wet-bulb temperature of the final supply air from the Cooling Section. Water that may condense in coil (1) is collected in tank (3), further cooling it.
Air from the described process then passes again through thermodynamic exchange system (2), further reducing its dry temperature. The resulting water is once again collected in tank (3). Air in these conditions now passes through the condenser coil of the direct expansion system (6), which is operational. Since this air is already well below outdoor air temperature, the system achieves significant energy savings in the cooling process of the unit's supply air, aided by the direct expansion system (6) with minimal electricity consumption. This working air is exhausted outside, hot and highly humid. Additionally, indoor air may be returned to the intake of this Pre-Cooling Section, greatly enhancing the energy efficiency of the unit by operating in recovery mode while still ensuring complete air renewal.
Outdoor air is driven to the Cooling Section intake and treated by water-air coil (4), now operating at an even lower temperature, cooling it again. Water that condenses in coil (4) is collected in tank (3) from which pump (BAT1) draws.
Under these new conditions, the air now passes through the evaporator coil of the direct expansion system (7), which is operational, cooling it with enthalpy variation and suctioning it at temperatures significantly below those of the outdoor air, thus saving electricity and increasing the unit's energy efficiency. Condensate from this coil is again collected in tank (3), further cooling it for reuse by pump (BAT1).
The air leaving evaporator coil (7) then passes through the adiabatic cooling medium (5), fed by pump (MED1), lowering its temperature once more. Unevaporated water, now at the air's wet temperature at that stage, is again collected in the Pre-Cooling Section's lower tank and sent to both water-air exchange coils (1), (4), and then to the adiabatic thermodynamic exchange system (2), repeating the entire process to continue reducing the supply air temperature into the building.
The unit configuration can be adapted, such as by adjusting the pump intake positions in the lower tank in both sections, or even by eliminating coil (1) to reduce the unit's cost while still maintaining high energy efficiency. The direct expansion system can also be eliminated, leaving the unit to operate solely under process A while still achieving very high energy efficiency.

Claims

High energy efficiency air conditioning system for buildings, including an inlet for suctioned outdoor air flow and an outlet for treated supply air flow, characterized in that it comprises:
a pre-cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (1) fed by water collected by a water pump (BAT1), an adiabatic exchange system (2), a water tank (3) for unevaporated water at a temperature close to the outdoor wet-bulb temperature, fed through said water pump (BAT1), and a condenser coil of the direct expansion system (6);

a cooling section that suctions outdoor air and includes a water-air thermodynamic exchange coil (4), a direct thermodynamic exchange system (5) fed by a water pump (MED1) delivering water from the pre-cooling tank (3), and an evaporator coil of the direct expansion system (7); and

a direct expansion system (8) installed in an adiabatic environment, activated from the already reduced temperature level reached by the adiabatic system (2), and from there to the temperature required to deliver the air to the exterior of the unit and to the interior of the building.
High energy efficiency air conditioning system for buildings, including an inlet for suctioned outdoor air flow and an outlet for treated supply air flow according to claim 1, characterized in that the system includes a sensorized control system dependent on outdoor air conditions, indoor building temperature, and the primary supply air temperature of the unit.
High energy efficiency air conditioning system for buildings, including an inlet for suctioned outdoor air flow and an outlet for treated supply air flow according to claim 1, characterized in that the system comprises four levels of air cooling: Ventilation, Indirect Cooling, Indirect/Direct, and Hybridization.
High energy efficiency air conditioning system for buildings, including an inlet for suctioned outdoor air flow and an outlet for treated supply air flow according to claim 1, characterized in that the direct expansion system (8) is a heat pump that reverses the cycle depending on whether hot or cold air needs to be supplied.
High energy efficiency air conditioning system for buildings, including an inlet for suctioned outdoor air flow and an outlet for treated supply air flow according to claim 1, characterized in that when supplying hot air, the Cooling Section recirculates part of the indoor air, and the Pre-Cooling Section recirculates the renewal indoor air, recovering this energy in the coil of the direct expansion system (8).