US20140370800A1

US20140370800A1 - Air distribution method

Info

Publication number: US20140370800A1
Application number: US14/175,851
Authority: US
Inventors: Adel Al ANSARI
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-06-14
Filing date: 2014-02-07
Publication date: 2014-12-18

Abstract

The present invention relates to an improved method of distributing fresh air into a building. The method comprises the steps of providing the fresh air; subjecting the fresh air to pre-cooling; channeling the pre-cooled fresh air into an air conditioning unit; and transferring the fresh air into the building's rooms. The fresh air displaces air within the rooms, which is exhausted out of the building without being channeled back to the cycle. The present invention aims to distribute fresh air into the building using an open air cycle to improve the indoor air quality (IAQ) at less energy consumption.

Description

FIELD OF THE INVENTION

The present invention relates to a method of distributing air. More particularly, the present invention relates to an improved method of distributing fresh air into a building.

BACKGROUND OF THE INVENTION

In the past few years, many systems have been developed to circulate air in the building. It is also found that, in the prior art, a wide variety of systems are made available for the purpose of improving air distribution within the buildings. In order to comply with some international or national regulations and guidelines, a minimum amount of fresh air is required to make-up in the building such that it reduces accumulation of carbon dioxide CO₂in stale air or constituents which may causes inhalation difficulties incur a mishap and spread contagious diseases. CO₂produced when people breath may accumulate in the building to an unacceptable level if the amount of outdoor air brought into and distributed throughout the building is insufficient. Basically, a chain of processes that includes bringing in outdoor air, conditioning and mixing the outdoor air with indoor air, distributing and exhausting some portion of the indoor air to outside, is important and no deterioration is tolerable at any situation. A process that does not consider the minimum requirement of ventilation as per standard such as an indoor AC unit which circulates the room air without any make-up of an outdoor air is a disadvantage.
As such, adequate ventilation for a healthy environment is crucial and must be provided and maintained in buildings where people live and work. However, in some cases, particularly in the case of a conventional variable air volume (VAV) system when it is in shutoff position, it is difficult to maintain a flow of fresh air into the building. In the design of effective ventilation system for buildings, the objective is normally to attain a steady state condition. Accordingly, fresh air should be controlled during the process of volumetric air flow to satisfy desired rooms and zones' setting conditions while keeping minimum required flow of fresh air for proper ventilation.
A heating, ventilating and air conditioning system, or HVAC as it is sometime referred to, for example, provides solutions for some of the problems in the prior art. The HVAC comprises, to condition air for cooling, an air conditioning (AC) unit which forces conditioned air to building so as to satisfy demands called by thermostat switch in rooms. It is found that the AC unit suffers from many drawbacks such as an increase in utility billing rate at this stage of minimum air flow where at least 30% air flow is required for all rooms to maintain the required flow of fresh air. In the case of buildings with many rooms for mix use, i.e. hospitals, hotels and any shared room's buildings, the HVAC standards & regulations require the installation multiple AC unit equivalent to the number of rooms and zones to prevent mixing of room air which results in high maintenance and an increase in utility bill charges. Despite compliance with the international American Society of Heating and Air-Conditioning Engineers (ASHRAE), the conventional design of HVAC system for buildings still delivers poor indoor air quality and increases utility demand.
U.S. Pat. No. 3,982,583 describes an optimized conditioning system which is useful in a variable volume air conditioning system where assures a predetermined amount of fresh air taken into a building. Also, described in the patent is an air property sensor adapted for regulating a damper means to maintain the minimum outdoor air at a predetermined value.
U.S. Pat. No. 5,862,982, on the other hand, describes optimal ventilation control strategy for multi zones ventilation systems which integrates flow rate standards with the concept of age of air. The later patent also describes the strategy to minimize the amount of outdoor air required to maintain the age of the zone air.
Taking into consideration of the above, the present invention aims to improve indoor air quality (IAQ) provided by the conventional AC unit for public buildings such as hospitals, schools and hotels with less energy consumption and which complies with international standards. The present invention aims to provide a solution to improve the indoor air quality (IAQ) by way of providing fresh air intake while exhausting accumulated carbon dioxide in the building with lesser energy consumption. It is important to note that the solution provided by the present invention is contradicted to the conventional art which describes a ventilation system with more fresh air but higher energy consumption.
Accordingly, it is desired to provide an improved method of distributing fresh air supplied into a building that involves less energy and provides efficient heat recovery. Although the teachings of the prior art disclose methods of distributing air into buildings, none specifically relates to an improved method of distributing fresh air as claimed in the present invention. Therefore, a need for the aforementioned features of the present invention is desired.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
It is an object of the present invention is to provide a method of distributing air for comfort conditioning by way of introducing absolute fresh air into a building.
It is another object of the present invention to provide a method of distributing fresh air that is capable of reducing the energy required to operate an air conditioning unit.
Accordingly, the present invention provides a method of distributing fresh air into a building that utilizes an open air cycle. The method comprises the steps of providing the fresh air; subjecting the fresh air to pre-cooling; channeling the pre-cooled fresh air into an air conditioning unit; and transferring the fresh air into the building's rooms. The fresh air displaces air within the rooms, which is exhausted out of the building without being channeled back to the cycle.
The fresh air increases the pressure in the room due to offset of more fresh air than the displaced air which reduces energy across the air-conditioning cooling coil. The increase of pressure in the room increases the temperature of the fresh air supplied to the room, wherein the increase of temperature reduces the temperature drop required for the pre-cooling.
It is an advantage of the present invention to provide an improved indoor air quality (IAQ) for ventilation of a building. The present invention is adapted to supply fresh air into the building and no recirculated air or return air will be channeled back to the cycle. It is an advantage that the present invention consumes less energy although the recirculated air is not utilized, and it is completed by way of engaging an improved heat recovery strategy to the cycle.
It is another advantage of the present invention to provide a uniformly air supply distribution in the building. The method involves an induction variable air volume valve damper which operates in accordance with the desired temperature and fan blow configured by a user. The induction variable air volume valve damper is configured to supply air flow comprises at least about 30% room air present in the building and eliminates cold air damping as well as regularly flushes the room air to cause comfort conditioning.
It is yet another advantage of the present invention to provide an improved method of distributing air which involves less number of unit operations such as air conditioning unit compared to conventional ventilation system. As a result, reliability of the unit upon installation and maintenance is substantially increased. It is also an advantage of the present invention to significantly reduce operation and installation costs, maintenance costs and utility billing rates to as higher as about 90% margin.
The foregoing and other objects, features, aspects and advantages of the present invention will become better understood from a careful reading of a detailed description provided herein below with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1A is a diagram of a conventional system of close air cycle taught by the prior art.

FIG. 1B is a diagram of a preferred embodiment of a system with air distribution method using open air cycle according to the present invention.

FIG. 2 is a block diagram of the preferred embodiment of the system for ventilation which comprises three energy recovery devices, including an organic cooling filter, an energy box unit and an air conditioning unit.

It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numberings represent like elements between the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention and its various embodiments can now be better understood by turning to the following detailed description wherein illustrated embodiments are described. It is to be expressly understood that the illustrated embodiments are set forth as examples and not by way of limitations on the invention as ultimately defined in the claims.
As used herein, the following terms carry the indicated meanings:
“Air conditioning unit” is the device that changes humidity levels, temperature or quality of air.
“Cubic Feet per Minute” is the measurement of airflow volume.
“Damper” is the device which can be found at the exit point of ductwork, this plate usually contains grates that can be opened or closed to control the flow of air into a zone.
“Heat Exchanger” is the device through which heat is transferred to a cold area or surface.
“Conditioned Air” is the air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within the “comfort zone.”
“Heating Load” is the rate of heat flow required to maintain a specific indoor temperature; usually measured in Btu per hour.
“IAP” is the indoor air pollution. “IAQ” is the indoor air quality.
“Outdoor Air” is the air taken from the external atmosphere and, therefore, not previously circulated through the system, sometimes referred to as “fresh air”.
“Return Air” is the air that is returned to a heating or cooling appliance from a heated or cooled space.
“Thermostat” is the sensors that monitor and control the output of an HVAC system.
“Ton (Air Conditioning)” is the unit of air cooling capacity; 12,000 Btu per hour.
“Variable Air Volume System (VAV)” is the air handling system that conditions the air to constant temperature and varies the outside airflow to ensure thermal comfort.
“Zoning” is the system that divides a home, office or space into different regions in order to better control the temperature and effectiveness of a heating and cooling system.
The present invention is also known as Less Energy All Fresh Air-Cold Air Distribution or “LEAFA-CAD” (registered trademarks). “LEAFA-BCS” is the abbreviation formed for Less Energy All Fresh Air—Building Cooling System.
ASHRAE, or American Society of Heating, Refrigerating, and Air Conditioning Engineers introduce ASHRAE Standard 62 which provides specific guidelines for minimum acceptable ventilation parameter. On the other hand, one is required to specify a minimum ventilation rates and indoor air quality (IAQ) that will be acceptable to human occupants and are intended to minimize the potential for adverse health effects. If local building codes reference ASHRAE Standard 62 the requirements of the standard become an integral part of the code. The minimum acceptable ventilation parameter includes in terms of outdoor air flow rates. The standard applies to all types of facilities, including dry cleaners, laundries, hotels, dormitories, retails stores, sports and amusement facilities, and teaching, convalescent and correctional facilities. The specified rates at which outdoor air must be supplied to each room within the facility range from 25 to 100 cubic meter per hour per person, depending on the activities that normally occur in that room.
The inventor with his about 25 years experiences in designing & commissioning heating, ventilating and air-conditioning (HVAC) systems for more than hundreds of buildings and projects specifically related to air distribution for cooling, has recognized that by changing the air cycle between the air conditioning unit and the building is the secret for the solution. The air cycle in the prior art in FIG. 1 a is where the air conditioning unit will cool down the air across its coil and send it as supply air to the building and the same air will return back to the air conditioning unit. Thus, such cycle is considered to known as a close air cycle (CAC).
It is the idea and thought of the inventor that if such CAC is interchanged to an open air cycle (OAC) as illustrated in FIG. 1 b, then the indoor air quality (IAQ) problem in the prior art will be totally solved and being capable to control the amount of fresh air entering the building as it will be 100% fresh air which is the best ever choice for the IAQ in the building. Such new approach will be a roadmap to get out of the box and overcome the big challenge. Energy consumption is one of the main concerns in the present invention. Thus, it is preferred that the energy is controlled to be at par such that no consumption increment is implemented to make the new approach is the ultimate solution.
It is one of the drawbacks in the close air cycle (CAC) where the air conditioning (AC) unit designed for public buildings such as hotels, hospitals and schools never allow the mixing of the fresh air and room air from different rooms via one air conditioning unit as per standard by the ASHRAE and other local regulations. As a result, calculated actual peak load is increased by minimum of about 10% due to the different between the building block load and zone load as well as due to air conditioning selection according to the manufactures range of size. For example, a bigger building with multiple rooms has capacities which are higher than the actual peak load by at least 15%.
Accordingly, the concept of this invention is to provide a method of distributing fresh air into a building which is less energy all fresh air. The amount of fresh air in the close air cycle (prior art) is at the minimum percentage of about 10% (+) as recommended by ASHRAE standard or local regulations for any related building application. Meanwhile, in the present invention, the inventor has provided a new approach using the open air cycle which is predicted to provide 100% fresh air into the building.
The present invention with the open air cycle (OAC) allows such mixing rooms in one HVAC system. As for bigger building/rooms, an engineer could reduce the capacity of the units by about 15% due to the gain from the zones and block load plus the use of diversity factor. Surprisingly, the interchanged from the close air cycle (CAC) to the open air cycle (OAC) is proven to save energy of about 25-30%, and add credits to the system for ventilation according the present invention which is using the open air cycle while introducing all 100% fresh air into the building.
Considerable attention has been made on the method of distributing and introducing more fresh air into the building at a very less energy consumption as well as at reduced number of unit operations utilized in the OAC. The OAC of the present invention practices no return or circulated air being channeled back into the building's rooms. Furthermore, it is surprisingly to note that the present invention which adapted the abovementioned OAC harvests significant increased IAQ, increased reliability and availability, while consumes lesser energy of about 30-50%, reduced operation and maintenance costs up to 90%, and involves lesser number of unit operations.
The present invention will now be described with referring to the drawings with specific numberings.
In FIG. 1A, a conventional system of close air cycle taught by the prior art is designated by a reference numeral 100. Outdoor fresh air 112 initially enters into a building 110 and subsequently an HVAC assembly 190 which cools down the fresh air 112 across its coil. The HVAC assembly 190 then delivers the cooled fresh air 112 into a room 118 inside the building 110 in a direction 120. The cooled fresh air 112 then circulates in the room 118 and displaces room air 116, while keeping the room air 116 inside the building 110. The displaced room air 116 then returns back to the HVAC assembly 190 in a direction 122. As shown, the conventional system 100 recycles the displaced room air 116 back into the system, resulting in only 10% distribution of the fresh air 112 into the room 118.
FIG. 1B illustrates a preferred embodiment of a system with air distribution method using open air cycle according to the present application, designated by a reference numeral 300. As shown, in the preferred embodiment 300, fresh air 212 enters into a building 210 and subsequently an HVAC assembly 290, which subsequently cools down the fresh air 212. The cooled fresh air 212 then enters a room 218 inside the building 210 in a direction 220, circulates in the room 218 and displaces room air 216. However, instead of recycling the room air 216 back into the HVAC assembly 290, the room air 216 exits the room 218 to the outside of the building 210 in a direction 224. Therefore, as illustrated, the preferred embodiment 300 allows for 100% distribution of the fresh air 212 into the room 218.
FIG. 2 illustrates in greater detail the preferred embodiment of the open air cycle system 300. Preferably, the building 210 is being conditioned by way of introducing and distributing all the fresh air 212 than the conventional system 100. More preferably, the distribution of the fresh air 212 into the building 210 consumes less energy compared to the prior art. The preferred system 300 comprises the HVAC assembly 290, which further comprises a pre-cooling unit 200 and an air conditioning unit 201. It is preferred that the arrangement of the devices in the system 300 is as shown in FIG. 2. The pre-cooling unit 200 is configured to pre-cooling the fresh air 212 supplied into the system 300. Preferably, the pre-cooling unit 200 is configured to filter, clean and reduce temperature of the fresh air 212 supplied into the system 300. According to a preferred embodiment, the pre-cooling unit 200 may be an air-to-air heat exchanger or energy wheel. Also, according to another preferred embodiment, the pre-cooling unit 200 may be a water-to-air heat exchanger. According to yet another preferred embodiment, the pre-cooling unit 200 also may be combinations of the air-to-air heat exchanger, energy wheel, water-to-air heat exchanger, and the like. It is preferred that temperature of the fresh air 212 upon exiting the pre-cooling unit 200 is reduced by about 14 degree Celsius.
It is the concept of the present invention that the room air 216 is exhausted out of the building 210 without being channeled back into a ventilation system (not illustrated). The exhausted or displaced room air 216 may be used for some other specific purposes.
In one preferred embodiment according to the present invention, as for the building 210 which requires cooling, an increased amount of the fresh air 212 will be introduced into the building 210 with lesser exhaust air being ejected outside of the building 210. As the desired cooling temperature of the building 210 is met, the fresh air 212 intake is reduced to a lower flow rate. It is understood that various options and scenarios can be implemented by designer(s) in order to optimize usage of energy through air distribution of cooling fresh air 212 supplied by the AC unit 201 while in the conventional system 100 the same is not possible. The use of different offsets can be implemented which include providing rooms with, but not limited to, 3 pulses, 2 pulses, 1 pulse and zero, i.e. 300 cfm, 200 cfm, and 100 cfm.
In another preferred embodiment according to the present invention, the method of distributing the fresh air 212 into the building 210 using the preferred system 300 comprises the steps of:

- i. providing the fresh air 212;
- ii. subjecting the fresh air 212 to pre-cooling;
- iii. channeling the pre-cooled fresh air 212 into the air conditioning unit 201; and
- iv. transferring the fresh air 212 into the building 210's room 218.

The fresh air 212 displaces the room air 216 within the room 218, which is exhausted out of the building 210 without being channeled back to the cycle of the preferred system 300. The fresh air 212 reduces carbon dioxide level in the room 218 to improve the IAQ. The fresh air 212 increases pressure in the room 212 due to offset of more of the fresh air 212 than the displaced air 216 which reduces energy across the air-conditioning cooling coil of the unit 201. The increase of pressure in the room 218 increases the temperature of the fresh air 212 supplied to the room 218, wherein the increase of temperature reduces temperature drop required for the pre-cooling.

EXPERIMENTAL EXAMPLE

The following specific embodiments are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. The preferred embodiment will now be described in further detail by way of an experimental example.
The experimental example is done with an existing 5 ton DX package unit (12 years old) with additional changes made to the unit as follows:

- Return line is cut and being connected to an exhaust fan (not illustrated) for exhausting all return air to outside of the building 210 through a roof; and
- The outdoor fresh air 212 is supplied to the AC system 201 through the pre-cooling unit 200 prior to be supplied to the AC unit 201's cooling coil and denoted as ECT.

If the conventional system with close air cycle (CAC) 10 circulates 2000 CFM to the room/zone 218 for cooling the air 212 down to 72.5° F. or 22.5° C., then the comparison of energy consumption calculations is:

TABLE 1

Sample calculation

	Present Invention with
Close Air Cycle	Open Air Cycle

Room temperature, RT = 72.5° F.	Room temperature, RT = 72.5° F.
Outdoor air temp. = 90.5° F.	Outdoor air temp. = 90.5° F. on March
	14^th, 2013 @ 4:40 pm
Return air temp. entering coiling coil:	All (100%) fresh outdoor air temp.:
→ECT = 76.1° F.	→ECT = 73.0° F.
Air Leaving the cooling coil temp.:	Air leaving the cooling coil temp.:
LCT = ? (unknown)	→LCT = 56.12° F.
(Q)coil = 1.1 × (CFM) × (ECT − LCT), then
LCT = ECT − (Q)coil/1.1 × (CFM)
LCT = 76.1 − 37136/1.1 × 2000
→LCT = 59.2° F.
Cooling Coil System Sensible Energy:	Cooling Coil System Sensible Energy:
(Q)coil = 1.1 × CFM × (ECT − LCT)	(Q)coil = 1.1 × CFM × (ECT − LCT)
(Q)coil = 1.1 × 2000 × (76.1 − 59.2)	(Q)coil = 1.1 × 2000 (72.5 − 56.12)
→(Q)coil = 37180 BTUH	→ (Q)coil = 37136 BTUH
→Higher with 0.12%
Room Grille Supply Temp. with	Room Grille Supply Temp. with increase
increase of 3° F.:	of 3° F.:
→GST = 62.2° F.	→GST = 59.12° F.
Room Energy equals to (Q)room:	Room Energy equals to (Q)room:
(Q)room = 1.1 × (CFM) × (Room	(Q)room = 1.1 × (CFM) × (GST − Room
Temp. − GST) =	Temp.) =
1.1 × 2000 × (72.5 − 62.2)	1.1 × 2000 × (72.5 − 59.12)
→(Q)room2 = 22660 BTUH	→(Q)room1 = 29436 BTUH
	→Higher with 30%

Based on Table 1, the distribution of the fresh air 212 into the building 210 has increased the pressure in the room 218 due to offset of more of the fresh air 212 than the displaced air 216. The increase of pressure in the room 218 increases the temperature (refer LCT) of the fresh air 212 supplied to the room 218, i.e. temperature of air leaving the cooling coil. The increase of the temperature (see LCT) reduces the temperature drop required for the pre-cooling. Thus, such temperature drop reduces energy required across the air-conditioning cooling coil.
The preferred embodiment 300 distributes 100% of the fresh outdoor air 212 into the building 210 with higher efficiency of performance that is equivalent to reduction in energy consumption of about 30%.
Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of examples and that they should not be taken as limiting the invention as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the invention includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations.
The words used in this specification to describe the invention and its various embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification the generic structure, material or acts of which they represent a single species.
The definitions of the words or elements of the following claims are, therefore, defined in this specification to not only include the combination of elements which are literally set forth. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements in the claims below or that a single element may be substituted for two or more elements in a claim. Although elements may be described above as acting in certain combinations and even initially claimed as such, it is to be expressly understood that one or more elements from a claimed combination can in some cases be excised from the combination and that the claimed combination may be directed to a subcombination or variation of a subcombination.
Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.
The claims are thus to be understood to include what is specifically illustrated and described above, what is conceptionally equivalent, what can be obviously substituted and also what incorporates the essential idea of the invention.

Claims

1. A method of distributing fresh air into a building using an open air cycle, comprising the steps of:

providing the fresh air;

subjecting the fresh air to pre-cooling;

channeling the pre-cooled fresh air into an air conditioning unit; and

transferring the fresh air into a room inside the building;

wherein the fresh air displaces air within the rooms, the displaced air being exhausted out of the building without being channeled back to the cycle.

2. A method according to claim 1, wherein the fresh air reduces carbon dioxide level in the room to improve indoor air quality (IAQ).

3. A method according to claim 1, wherein the fresh air increases pressure in the room due to offset of more of the fresh air than the displaced air which reduces energy across an air-conditioning cooling coil.

4. A method according to claim 1, wherein an increase of pressure in the room increases temperature of the fresh air supplied to the room, wherein the increase of temperature reduces temperature drop required for the pre-cooling.