US20070158049A1

US20070158049A1 - Ventilation system

Info

Publication number: US20070158049A1
Application number: US11/464,682
Authority: US
Inventors: Kyung Hwan Kim; Keun Choi; Dong CHOI; Ho Choi
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2005-08-16
Filing date: 2006-08-15
Publication date: 2007-07-12
Also published as: CN1916517A; CN100441969C; KR100651879B1; JP2007051864A

Abstract

A ventilation system is disclosed. The ventilation system of the present invention includes a heat-exchanger having at least two unit heat-exchange elements arranged in parallel for heat exchange between supplied outside air and exhausted room air, an air-supply duct having one side for making an outdoors be in communication with an inside of the heat-exchanger and the other side for making an indoor space be in communication with the inside of the heat-exchanger to supply outside air into the indoor space, and an air-exhaust duct having one side for making the indoor space be in communication with the inside of the heat-exchanger and the other side for making the outdoors be in communication with the inside of the heat-exchanger to exhaust room air outdoors, wherein an air-supply channel is formed for making one side of the air-supply duct be in communication with the other side of the air-supply duct and an air-exhaust channel is formed in a diagonal direction of the air-supply channel for making one side of the air-exhaust duct be in communication with the other side of the air-exhaust duct within the heat-exchanger.

Description

This application claims the benefit of the Patent Korean Application No. P2005-74693, filed on Aug. 16, 2005, which are hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a ventilation system, more particularly, to a ventilation system which improves heat-exchanging efficiency in a heat-exchanger.
2. Discussion of the Related Art
In general, ventilation means to make room air pleasant. More specifically, ventilation means to discharge and remove polluted room air outside to supply fresh outside air to a room, thereby making pleasant indoor circumstances maintained.
Air within an airtight space may contain more carbon dioxide due to human perspiration as time goes by. Hence, the high carbon dioxide content in a room may affect the human perspiration. Thus, in case that many people have to stay together in a small room such as an office or a vehicle, it is necessary to replace the polluted room air with fresh outside air regularly. A ventilation system is commonly used at that time.
According to a well-known conventional ventilation system in the related art, only room air is forcibly ventilated outside by using one ventilator. However, in case that only room air is forcibly ventilated outside by using one ventilator, cooled or heated room air is discharged outside without any filtering. Also, outside air is drawn through a door or a window shield without heat-exchanging, thereby resulting in causing unnecessary cost in cooling/heating a room.
Also, if cooled/heated air is suddenly drawn into a room from an outside, people in the room might feel unpleasant due to the drastically changed temperature. Especially, in case only room air is discharged outside in a state where a window shield or a door is closed, fresh outside air is shut off to cause an anoxia symptom. Hence, since humidity control for a room is not performed at all, pleasant internal circumstances in spite of a ventilation system provided therein.
To solve the above problem, a ventilation system has been suggested, in which outside air is heat-exchanged with room air discharged outside and then supplied into a room. Referring to FIG. 1, the above conventional ventilation system will be described.
Generally, the heat-exchanging type ventilation system includes a heat-exchanger 1 having a box shape, an air-supply channel in communication with an outside and an air-exhaust channel in communication with an inside of a room.
The heat-exchanger 1 is generally box-shaped and has an air-supply fan 15, an air-exhaust fan 25 and a heat-exchange element 5 provided therein.
The air-supply channel and the air-exhaust channel pass through the heat-exchanger 1. The air-supply channel passes an air-supply inlet 11, the inside of the heat-exchanger 1 and an air-supply outlet 13. The air-exhaust channel passes through an air-exhaust inlet 21, the inside of the heat-exchanger 1 and an air-exhaust outlet 23.
Thus, in the air-exhaust channel which discharges polluted room air outside, air flows to an internal air-exhaustion duct, the heat-exchanger and an external air-exhaustion duct in order. A first end of the internal air-exhaustion duct is in communication with a room and a second end thereof is connected to the air-exhaustion inlet 21 of the heat-exchanger 1. A first end of the external air-exhaustion duct is connected to the air-exhaust outlet 23 of the heat-exchanger 1 and a second end thereof is in communication with an outside.
Also, in the air-supply channel which supplies fresh outside air into a room, air flows to an external air-supply duct, the heat-exchanger and an internal air-supply duct in order. A first end of the external air-supply duct is in communication with an outside and a second thereof is connected to the air-supply inlet 11 of the heat-exchanger 1. A first end of the internal air-supply duct is connected to the air-supply outlet 13 of the heat-exchanger 1 and a second end thereof is in communication with a room.
As considering a cause of air flow, the air-supply fan 15 is operated to generate absorption force for absorbing outside air (OA). Hence, outside air (OA) is supplied into a room through the air-supply channel. Here, a reference of (SA) which is not described is ‘supply air’. Also, the air-exhaust fan 25 is operated to generate absorption force for absorbing room air (RA). Hence, room air (RA) is exhausted outside through the air-exhaust channel. Here, a reference of (EA) which is not described is ‘exhaust air’.
A way of heat-exchanging between room air (RA) and outside air (OA) drawn into the heat-exchanger 1 will be described.
First of all, room air (RA) is drawn to a first lower portion of the heat-exchange element 5 from the inside of the heat-exchanger 1 and discharged to a first upper portion of the heat-exchange element 5, and then the room air (RA) is out of the heat-exchanger 1. Together with that, outside air (OA) is drawn to a second lower portion of the heat-exchange element 5 from the inside of the heat-exchanger 1 and discharged to a second upper portion of the heat-exchange element 5, and then the outside air (OA) is out of the heat-exchanger 1.
That is, the path of the room air (RA) and the path of the outside air (OA) are crossed each other within the heat-exchange element 5. Heat between the room air (RA) and the outside air (OA) is exchanged through a side wall of each path.
Here, a heat-exchange element in which heat is exchanged by only temperature difference between the room air (RA) and the outside air (OA) is called as ‘sensible-heat-exchange element’. Whereas, a heat-exchange element in which heat is exchanged by humidity difference between RA and OA rather than the temperature difference is called as ‘total-heat-exchange element’.
Recently, the total-heat-exchange element is used a lot more to enhance heat-exchanging efficiency.
However, in the conventional ventilation system according to the related art described above, the size of the heat-exchange element 5 should be large to enhance heat-exchanging efficiency, thereby causing a problem that the height of the heat-exchanger 1 should be high.
By the way, according to the conventional ventilation system operated by relatively high wind force, flux of air draw in into the heat-exchange element 5 is getting fast. Thereby, the faster the air flux is getting, the lower heat-exchanging efficiency should be getting.
Thus, the volume of the heat-exchange element 5 should be large. Although the heat-exchanger 1, generally, is installed on a ceiling of a room, the height of the heat-exchanger 1 is getting high to enlarge the volume of the heat-exchange element 5. Thereby, to compensate that, there may be a problem that the height between each floor of a building should be higher.
Therefore, it is preferred that the height of the heat-exchanger 1 is not more than a predetermined height and there have been demands for a heat-exchanger 1 which can enhance heat-exchanging efficiency without enlarging the height of the heat-exchanger 1.
Furthermore, the conventional heat-exchanger 1 has a problem of high production cost, because the heat-exchange element 5 should be changed according to the size of the heat-exchanger 1.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a ventilation system.
An object of the present invention is to provide a ventilation system which can maintain height of a heat-exchanger uniformly with high heat-exchange efficiency.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a ventilation system includes a heat-exchanger having at least two unit heat-exchange elements arranged in parallel for heat exchange between supplied outside air and exhausted room air; an air-supply duct having one side for making an outdoors be in communication with an inside of the heat-exchanger and the other side for making an indoor space be in communication with the inside of the heat-exchanger to supply outside air into the indoor space; an air-exhaust duct having one side for making the indoor space be in communication with the inside of the heat-exchanger and the other side for making the outdoors be in communication with the inside of the heat-exchanger to exhaust room air outdoors, wherein an air-supply channel is formed for making one side of the air-supply duct be in communication with the other side of the air-supply duct, and an air-exhaust channel is formed in a diagonal direction of the air-supply channel for making one side of the air-exhaust duct be in communication with the other side of the air-exhaust duct within the heat-exchanger.
Here, the ventilation system of present invention may further includes an air-supply fan scroll having an air-supply fan for supplying outside air into the indoor space in the air-supply channel and a motor for operating the air-supply fan, and an air-exhaust fan scroll having an air-exhaust fan for exhausting room air outdoor in the air-exhaust channel and a motor for operating the air-exhaust fan. The air-supply fan scroll and the air-exhaust fan scroll may be provided in the same portion of the heat-exchanger with respect to the heat-exchange element.
The air-supply channel and the air-exhaust channel may be in right/left and upward/downward symmetry. The ventilation system further comprises a guide for partitioning off the air-supply channel and the air-exhaust channel.
The heat-exchanger further includes a bypass channel for supplying outside air into the indoor space without outside air passing the unit heat-exchange element, and a bypass damper for selectively shutting off the bypass channel.
The air-supply fan and the air-exhaust fan may be double suction fans, respectively. The unit heat-exchange element is a total-heat-exchange element. More specifically, the unit heat-exchange element may be a hexagonal parallel type heat-exchange element.
Preferably, the air passing through the unit heat-exchange element is drawn from an air drawing surface of the unit heat-exchange element in a diagonal direction with respect to a center of the unit heat-exchange element and discharged from an air discharging surface of the unit heat-exchanging surface in a diagonal direction with respect to a center of the unit heat-exchange element.
Here, the ventilation system according to the present invention may further include a channel guide casing formed on an air drawing surface and an air discharging surface of the unit heat-exchange element to drawn/discharge air in a diagonal direction with respect to the center of the unit heat-exchange element. The air-supply channel and the air-exhaust channel are partitioned by a guide within the heat-exchanger, the air-supply channel and the air-exhaust channel are in a right/left and upward/downward symmetry within the heat-exchanger.
The ventilation system of the present invention has following advantageous effects.
First, the ventilation system of the present invention has an advantageous effect of less pressure loss, because an air path within the heat-exchanger, especially within the heat-exchange element, is improved into a right/left and upward/downward air path.
Second, the ventilation system of the present invention has another advantageous effect of high heat-exchange efficiency, because the volume of the heat-exchange element is enlarged without increasing the height of the heat-exchanger.
Third, the ventilation system of the present invention has still another advantageous effect that capacity change of a ventilation system may be appropriately dealt with, because the heat-exchange element has a configuration in which the unit heat-exchange elements are connected in parallel.
Finally, the ventilation system of the present invention has still another advantageous effect of reduced pressure loss, because the air channel drawn/discharged into/from the unit heat-exchange element is improved more smoothly by the channel guide casing.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
FIG. 1 is a perspective view illustrating key parts of a conventional ventilation system according to the related art;
FIG. 2 is a perspective view illustrating a ventilation system according to an embodiment of the present invention;
FIG. 3 is perspective view illustrating a path within a heat-exchange element of a ventilation system according to the embodiment of the present invention; and
FIG. 4 is a perspective view schematically illustrating a configuration of a heat-exchanger of a ventilation system according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts and the detailed description thereof will be omitted.
As shown in FIG. 2, a ventilation system according to an embodiment of the present invention includes a heat-exchanger 100, an air-supply duct (not shown), an air-exhaust duct (not shown), an air-supply channel 120 and air-exhaust channel 130.
A heat-exchange element 140 is provided in the heat-exchanger 100 to allow supplied outside air (OA) and exhausted room air (RA) heat-exchanged. The heat-exchange element 140 has at least two unit heat-exchange elements 141 connected each other in parallel. In FIG. 2, six unit heat-exchange elements 141 are connected in parallel.
The unit heat-exchange element 141 may be a sensible-heat-exchange element which exchanges heat-exchanges by using temperature difference between the outside air (OA) and the room air (RA). Preferably, the unit heat-exchange element 141 is a total-heat-exchange element which heat-exchanges by using humidity difference as well as temperature difference to enhance heat-exchanging efficiency.
An air-supply duct has one side for making an outdoors be in communication with an inside of the heat-exchanger 100 and the other side for making an indoor space be in communication with the inside of the heat-exchanger 100 to supply outside air (OA) into the indoor space.
Likewise, an air-exhaust duct has one side for making the indoor space be in communication with the inside of the heat-exchanger 100 and the other side for making the outdoors be in communication with the inside of the heat-exchanger 100 to exhaust room air (RA) into the room.
An air-supply channel 120 is formed for making one side of the air-supply duct be in communication with the other side of the air-supply duct and an air-exhaust channel 130 is formed for making one side of the air-exhaust duct be in communication with the other side of the air-exhaust duct within the heat-exchanger.
The air-supply channel 120 and the air-exhaust channel 130 pass through the heat-exchanger 100 and cross each other in a diagonal direction within the heat-exchanger 100.
First of all, an air-exhaust channel (130, illustrated as dotted line arrows in the drawings) is formed within the heat-exchanger 100 so that room air (RA) is drawn into the heat-exchange element 140 through an air-exhaust inlet 131 and drawn from a first lower portion of the heat-exchanger 100 into the heat-exchange element 140 to be discharged from a second upper portion of the heat-exchanger 100 to the outdoors through an air-exhaust outlet 132.
Whereas, an air-supply channel (120, illustrated as solid line arrows in the drawings) is formed so that outside air (OA) is drawn into the heat-exchanger 100 through an air-supply inlet 121 and drawn from a first upper portion of the heat-exchanger 100 into the heat-exchange element 140 to be drawn from a second lower portion of the heat-exchanger 100 into the indoor space through an air-supply outlet 122.
Thus, the air-supply channel 120 and air-exhaust channel 130 within the heat-exchanger 100 are diagonally formed. Thereby, the heat-exchanger 100 of the present invention has less air inflow resistance than the heat-exchanger of the related art illustrated in FIG. 1.
Two chambers are formed in both opposite sides within the heat-exchanger 100 with respect to the heat-exchange element 140 to divide a case 110 of the heat-exchanger 100 into an upper/lower chamber, and the upper and lower chamber are partitioned by a guide 146. Thus, the air-supply channel 120 and the air-exhaust channel 130 formed within the heat-exchanger 100 which has had one case 110 are in right/left and upward/downward symmetry.
Also, it is preferred that an air-supply fan scroll 125 and an air-exhaust fan scroll 135 are provided within the heat-exchanger 100. The air-supply fan scroll 125 includes an air-supply fan for supplying outside air (OA) into the indoor space in the air-supply channel 120 and a motor for operating the air-supply fan. The air-exhaust fan scroll 135 includes an air-supply fan for exhausting room air (RA) outdoors in the air-exhaust channel 130 and a motor for operating the air-exhaust fan. That is for enabling a compact configuration of the heat-exchanger 100 and for facilitating the installment of the entire ventilation system without any difficulties.
Also, it is preferred that the air-supply fan scroll 125 and the air-exhaust fan scroll 135 are provided in the same portion of the heat-exchanger 100 with respect to the heat-exchange element 140 so that the air-exhaust channel 130 and the air-supply channel 120 may be formed in a diagonal direction and air may be drawn without being pushed to uniformly distribute air inflow into each unit heat-exchange element 141 connected in parallel.
As shown in FIG. 2, air is drawn into both opposite sides of each fan and discharged. It is necessary that a smooth air path should be formed to reduce pressure loss. Thus, preferably, the air-supply fan and the air-exhaust fan are double suction fans.
A reference number of 145 which is not described is a bypass channel and the bypass channel will be described in another embodiment of the present invention later.
Next, the heat-exchange element 140 will be described in detail.
As shown in FIG. 2, the heat-exchange element 141 of the heat-exchanger 100 according to the embodiment of the present invention includes at least two unit heat-exchange elements 141 connected each other in parallel.
Although a hexagonal unit heat-exchange element 141 is illustrated in FIG. 2, it is also possible that a conventional tetragonal heat-exchange element, which makes an air path therein a cross flow type, may be used as a unit heat-exchange element.
However, the hexagonal unit heat-exchange element 141 which makes an air path a parallel flow type is preferred to enhance heat-exchanging efficiency.
Here, the parallel flow type is similar to a counter flow type of a conventional hexagonal heat-exchange element. An air path of the conventional counter flow type is in parallel each other and the direction of air flow is opposite. However, the air path of the parallel flow type is in parallel each other and the direction of air flow is also the same.
FIG. 3 schematically illustrates an air path within the unit heat-exchange element 141 and FIG. 3 illustrates the unit heat-exchange element 141 of FIG. 2 which is laid down on description's sake.
As shown in FIG. 3, an air path layer 148 where room air (RA) is drawn and exhausted outdoors and an air path layer 149 where outside air (OA) is drawn and exhausted into the indoor space are overlapped in the unit heat-exchange element 141. A heat-exchange film (not shown) is provided between the air path layers to allow heat between both layers exchanged.
Here, a rear right surface of the unit heat-exchange element 141 with respect to the unit heat-exchange element 141 is an air drawing surface where room air (RA) is drawn, and a front left surface thereof with respect to the unit heat-exchange element 141 is an air discharging surface where heat-exchanged room air (RA) is exhausted. Also, a front right surface of the unit heat-exchange element 141 with respect to the unit heat-exchange element 141 is an air drawing surface where outside air (OA) is drawn, and a rear left surface thereof with respect to the unit heat-exchange element 141 is an air discharging surface where outside air (OA) is exhausted.
Heat-exchanging within the unit heat-exchange element 141 is performed in a cross flow type, after air is drawn into the unit heat-exchange element 141 and before air is discharged. Hence, an air path is formed in parallel in a center of the unit heat-exchange element 141 to perform heat-exchanging in a parallel flow type.
Here, it is known that heat-exchange ratio is higher in a counter flow type or a parallel flow type (the parallel flow type according to the present invention) than in the cross flow type.
The volume of the heat-exchange element 140 may be enlarged by parallel connection of the unit heat-exchange element 141 as required in a ventilation system with a high air force. Thereby, heat-exchanging efficiency may be enhanced by enlarging the number of the unit heat-exchange element 141. At that time, it is preferred that the unit heat-exchange element 141 is attachable/detachable in a vertical direction of the heat-exchanger 100.
That is, if the unit heat-exchange element 141 is used, the number of the unit heat-exchange element 141 is adjusted without changing the entire heat-exchanger 100 or the heat-exchange element 140 even in case that the capacity of the ventilation system is changed. Thereby, capacity variation may be appropriately dealt with.
Referring to FIG. 4, another embodiment of the present invention will be described and the same description as the embodiment will be omitted.
FIG. 4 is a perspective view illustrating a heat-exchanger of a ventilation system according to another embodiment of the present invention.
According to another embodiment, the same unit heat-exchange element as the embodiment is provided. But, it is different that a predetermined guide casing is further provided on an air inlet surface and an air outlet surface of the unit heat-exchange element and the other configurations are the same.
That is, an air-supply channel and an air-exhaust channel formed within a heat-exchanger 200 are the same as described in the above embodiment. Thus, in another embodiment, only the unit heat-exchange element 241 will be described.
As shown in FIG. 4, a channel guide casing 242 and 243 is further provided on an upper portion of the each unit heat-exchange element 241.
That is, drawn outside air (OA) is not perpendicularly drawn toward a center of unit heat-exchange element 241, but diagonally drawn into an air drawn surface by the channel guide casing 242 and 243. In other words, a left portion of the channel guide 243 forms a channel for allowing air drawn therein in a predetermined direction of the air drawn surface of the unit heat-exchange element 241.
Here, an air path drawn into the unit heat-exchange element 241 is formed narrowly by the left portion of the channel guide casing 242 and 243. Thereby, the channel may be formed smoothly to reduce pressure loss.
Meanwhile, outside air (OA) drawn in a diagonal direction is heat-exchanged within the heat-exchange element 240 and discharged outside by the channel guide casing 242 and 243 formed in a lower portion of the each unit heat-exchange element 241.
In that case, outside air (OA) is diagonally discharged from the air discharging surface of the unit heat-exchange element 241.
Briefly, the channel guide casing 242 and 243 is provided on the air drawing surface and the air discharging surface of the unit heat-exchange element 241 to form a channel drawing/discharging air in a diagonal direction with respect to the center of the unit heat-exchange element 241, not in a perpendicular direction.
Room air (RA) drawn through an air-exhaust inlet 221 is diagonally drawn in a lower left direction of the unit heat-exchange element 241 and diagonally discharged in an upper right direction of the unit heat-exchange element 241.
As described above, since the channel of the unit heat-exchange element 241 is formed in a right/left and upward/downward direction, the shape of the channel drawn/discharged into/from each unit heat-exchange element 241 may be formed smoothly. Thus, the air-supply channel and the air-exhaust channel are formed in an S-shape from a view of the entire heat-exchanger 200.
Thereby, the ventilation system according to the present invention has an advantageous effect that pressure loss may be reduced.
Preferably, the heat- exchanger 100 and 200 of the ventilation system according to the present invention further includes a bypass channel 145 and 245 for supplying outside air into the indoor space without outside air passing the unit heat-exchange element, and a bypass damper (not shown) for selectively shutting off the bypass channel.
In case that the temperature of outside air (OA) and the temperature of room air (RA) is almost the same, ventilation is performed through the heat- exchange element 140 and 240 not to consume unnecessary electricity. In that case, the bypass channel 145 and 245 connected to the air- exhaust fan scroll 135 and 235 is opened without room air (RA) exhausted outdoors passing the heat- exchange element 140 and 240. The bypass damper (not shown) selectively opens the bypass channel.
The bypass channel 145 and 245 and the bypass damper may be provided in the channel supplied into a room or both channels supplied/exhausted into/to a(n) room/outside.
The heat- exchanger 100 and 200 of the ventilation system according to the present invention may perform air cleansing as well as heat-exchange, because a filter (not shown) is further provided for filtering foreign substances of air before air is drawn into the heat- exchange element 140 and 240.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A ventilation system comprising:

a heat-exchanger having at least two unit heat-exchange elements arranged in parallel for heat exchange between supplied outside air and exhausted room air;

an air-supply duct having one side for making an outdoors be in communication with an inside of the heat-exchanger and the other side for making an indoor space be room in communication with the inside of the heat-exchanger to supply outside air into the indoor space; and

an air-exhaust duct having one side for making the indoor space be in communication with the inside of the heat-exchanger and the other side for making the outdoors be in communication with the inside of the heat-exchanger to exhaust room air outdoors;

wherein an air-supply channel is formed for making one side of the air-supply duct be in communication with the other side of the air-supply duct and an air-exhaust channel is formed in a diagonal direction of the air-supply channel for making one side of the air-exhaust duct be in communication with the other side of the air-exhaust duct within the heat-exchanger.

2. The ventilation system of claim 1, further comprising,

an air-supply fan scroll having an air-supply fan for supplying outside air into the indoor space in the air-supply channel and a motor for operating the air-supply fan, and

an air-exhaust fan scroll having an air-exhaust fan for exhausting room air outdoors in the air-exhaust channel and a motor for operating the air-exhaust fan.

3. The ventilation system of claim 2, wherein the air-supply fan scroll and the air-exhaust fan scroll are provided in the same portion of the heat-exchanger with respect to the heat-exchange element.

4. The ventilation system of claim 3, wherein the air-supply channel and the air-exhaust channel are in right/left and upward/downward symmetry.

5. The ventilation system of claim 4, further comprising a guide for partitioning off the air supply channel from the air-exhaust channel.

6. The ventilation system of claim 5, wherein the heat-exchanger further comprises,

a bypass channel for supplying outside air into the indoor space without outside air passing the unit heat-exchange element, and

a bypass damper for selectively shutting off the bypass channel.

7. The ventilation system of claim 2, wherein the air-supply fan and the air-exhaust fan are double suction fans, respectively.

8. The ventilation system of claim 1, wherein the unit heat-exchange element is a total-heat-exchange element.

9. The ventilation system of claim 8, wherein the unit heat-exchange element is a hexagonal parallel type heat-exchange element.

10. The ventilation system of claim 8, wherein the air passing through the unit heat-exchange element is drawn from an air drawing surface of the unit heat-exchange element in a diagonal direction with respect to a center of the unit heat-exchange element and discharged from an air discharging surface of the unit heat-exchanging surface in a diagonal direction with respect to a center of the unit heat-exchange element.

11. The ventilation system of claim 10, further comprising a channel guide casing formed on an air drawing surface and an air discharging surface of the unit heat-exchange element to drawn/discharge air in a diagonal direction with respect to the center of the unit heat-exchange element.

12. The ventilation system of claim 10, wherein the air-supply channel and the air-exhaust channel are partitioned by a guide within the heat-exchanger, the air-supply channel and the air-exhaust channel are in a right/left and upward/downward symmetry within the heat-exchanger.