WO2010104427A1

WO2010104427A1 - Air cleaning and heating system

Info

Publication number: WO2010104427A1
Application number: PCT/SE2009/050243
Authority: WO
Inventors: Stefan LYSÉN
Original assignee: Camfil Ab
Priority date: 2009-03-09
Filing date: 2009-03-09
Publication date: 2010-09-16

Abstract

The present invention relates to an air cleaning and heating system for a building having several rooms (I-VI) to be heated, said system comprises an air heater (1), means (12) for passing air through said air heater, channels (2, 3-8) for leading heated air from the air heater to each said room in said building, a mixing chamber (11) for mixing of air from inside the building and air from outside the building, said chamber being in connection with a channel leading air through said air heater, a channel (14) leading from means (15) for intake of air from outside of the building and having an outlet (13) in said mixing chamber, and means (9, 10) for leading used air to the outside of the building. According to the invention the outlet (13) for air from outside the building in said mixing chamber (11) is directed in a direction parallel to the flow direction of the air from the inside of the building in said mixing chamber, and a HEPA filter (18) is disposed in an inlet of a channel (17) leading from inside of the building to said mixing chamber.

Description

Air cleaning and heating system.

TECHNICAL FIELD

The present invention relates to an air cleaning and heating system for a building having several rooms to be heated, said system comprises an air heater and means for passing air through said air heater, channels for leading heated air from the air heater to each said room in said building, a mixing chamber for mixing of air from inside the building and air from outside the building, said chamber being in connection with a channel leading air through said air heater, a channel leading from means for intake of air from outside the building and having an outlet in said mixing chamber, and means for leading used air to the outside of the building.

BACKGROUND OF THE INVENTION

Heating and ventilation systems in which a mixture of air from outside the building and recirculated air from inside a building is passed through an air heater and delivered to rooms to be heated are known in the art. It is known to let the air from outside of the building and the recirculated air pass filters before entering the air heater but the cleaning effect in known system is not enough for fulfilling the need for clean air of for example allergic persons or other persons having a need for clean air. Moreover, such systems are not suitable for varying the amount of air passing through filters in dependence of the desired quality of the air inside the building and at the same time maintain a constant amount of air per time unit from outside of the building being delivered to the system. The object of the present invention is a versatile air cleaning and heating system able to produce a high quality of the air inside a building and in which the recirculation rate of inside air can be varied so that the amount of inside air per time unit passing a filter can be increased without increasing the amount per time unit of air from outside of the building being delivered to the inside of the building.

SUMMARY OF THE INVENTION

This object is accomplished by an air cleaning and heating system for a building having several rooms to be heated, said system comprises an air heater and means for passing air through said air heater, channels for leading heated air from the air heater to each said room in said building, a mixing chamber for mixing of air from inside the building and air from outside of the building, said chamber being in connection with a channel leading air through said air heater, a channel leading from means for intake of air from outside of the building and having an outlet in said mixing chamber, and means for leading used air to the outside of the building, characterized in that the outlet for air from outside of the building in said chamber is directed in a direction parallel to the flow direction of the air from the inside of the building in said mixing chamber, and in that a HEPA filter is disposed in an inlet of a channel leading from inside of the building to said mixing chamber. By disposing the HEPA filter in said inlet it is ensured that only cleaned air is passing in the delivery side of the system and by said arrangement of the outlet for air from outside of the building in the mixing chamber it is ensured that an increasing flow of recirculated air will not reduce the inflow of air from outside of the building. Thereby the rate of recirculated air can be controlled in dependence of the pollution grade of the inside air and without consideration of the inflow of air from outside the building. In a preferred embodiment, said means for passing air through said air heater is a fan disposed downstream of said air heater in a main channel for leading heated air to said rooms, and said means for intake of air from outside of the building is a fan disposed in the channel leading air from outside of the building to the mixing chamber. To advantage, a heat exchanger, preferably a rotary heat exchanger, is arranged to preheat air from outside of the building with the aid of the used air leaving the building.

Said fan for delivering air from outside of the building to the mixing chamber is preferably controlled to deliver a constant amount of air per unit of time whereas the fan for circulation of the mixture of air from the mixing chamber through the system is variable in dependence of the need for air cleaning.

The air heater is preferably an air-to-air heat pump.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described with reference to the enclosed figure 1 , in which an air cleaning and heating system for a building according to a preferred embodiment of the invention is schematically disclosed.

DESCRIPTION OF EMBODIMENTS

In figure 1 is schematically shown an air cleaning and heating system for a building having several rooms I- VI to be heated. The building shown in the example is a private home but the system according to the invention can be installed in other types of buildings, such as office buildings, schools and day care centres. Said system comprises an air heater 1 and a main channel 2 for leading heated air from the air heater to said rooms. From the main channel 2 lead channels 3-8 to each room I- VI and deliver heated air thereto, as indicated by arrows in figure 1. A fan 9 draws used air from the inside of the building from a channel 10 and deliver the used air to the outside of the building. Some, IV, V and VI, of the rooms I- VI have channels leading to channel 10. A part of the air inside the building is recirculated to the main channel 2 for heated air by being drawn into a mixing chamber 11 by a fan 12 and thereafter being fed to air heater 1. The fan 12 is disposed in the main channel 2 downstream of the air heater 1. A constant flow of air from outside of the building is also delivered into the mixing chamber 11 via the outlet 13 of a channel 14. A fan 15 provides for a constant amount of air per time unit from outside of the building being delivered to the mixing chamber. Thus, air from outside the building and recirculated air from inside the building are mixed in the mixing chamber before entering the fan 12 and passing the heater 1.

The air from outside the building is preheated in a heat exchanger 16, preferably a rotating heat exchanger, by the used air in channel 10 before entering the mixing chamber 11. A further preheating of the air from outside the building by air from inside the building occurs in the mixing chamber.

Room VI is a kitchen and the channel of its kitchen fan 20 leads directly to the outside of the building.

A HEPA (High Efficiency Particulate Air) filter 18 is disposed in an inlet of a channel 17 leading from inside the building to said mixing chamber 11 and the air from outside the building in channel 14 passes a filter 19, which preferably is a fine filter of F7-F9 class, before entering the heat exchanger 16. Thereby only cleaned air enters the mixing chamber and only clean air is thus delivered to rooms I- VI. As is evident from figure 1, the outlet 13 for air from outside of the building in the mixing chamber 11 is directed in a direction parallel to the flow direction of the recirculated air from the inside of the building drawn into the mixing chamber 11 by fan 12. Thereby the flows of air from outside the building and recirculated air will influence each other by a kind of ejector effect so that a free flow of the air from outside of the building will not be negatively influenced by possible pressure fluctuations in the mixing chamber.

The fan 15 delivering air from outside of the building into the mixing chamber is controlled such that a constant amount of air per time unit from outside of the building is delivered to the mixing chamber, said amount of air per time unit approximately corresponding to the amount of used air per time unit being drawn out of the building through channel 10 by fan 9. Usually the amount of air from the outside of the building per time unit delivered to the building is slightly less than the amount of used air per time unit leaving the building in order not to create an overpressure within the building .

The fan 12 is in a basic state controlled so that a certain amount of inside air per time unit is cleaned by passing through filter 18 before entering the mixing chamber. By placing the filter 18 connected to the inlet of channel 17 it is ensured that only cleaned inside air is flowing in channel 17, the mixing chamber, channels leading to and from fan 12 and the main channel 2. In the basic state it is ensured that the air inside the building has a required level of cleanliness during normal pollution of the air inside the building. However, if the pollution of air for some reason, such as vacuum cleaning or other cleaning operations or the lightning of candles or an open fire stove, is increased, the fan 12 can be controlled to delivered air at a higher flow rate, i.e. a higher amount of air per time unit. Since the amount of air from outside the building per time unit being delivered into the mixing chamber by fan 15 is constant, it is only the amount of recirculated inside air per time unit that will be increased thereby. By increasing the flow rate of the recirculating air, the inside air will be rapidly cleaned from pollutions. It is to be noted that a higher than normal rate of recirculated inside air can be obtained by controlling fan 12 if a higher than normal level of cleanliness of the inside air is required, for example if the persons in the building are allergic.

It is of course also possible to increase the amount per time unit of air from outside the building being delivered by the fan 15 if needed, for example if. more people than usual will be present in the building. Such adjustment can be done independent of the regulation of the amount of recirculating inside air per time unit be made by controlling fan 12.

By the present air cleaning and heating system it is thus possible to obtain the desired quality of the air inside the building both with regard to oxygen content and content of pollutions, the regulation of the system for obtaining a desired oxygen content and the desired level of cleanliness being independent of each other. This independence can lead to cost savings since the cleanliness can be regulated without increase of the amount of air per time unit from outside the building delivered to the system.

The system can be manually controlled or sensors for measuring particle pollution and oxygen content of the inside air can be installed and coupled to a computer or the like for automatic regulation of the system in dependence of the measured values.

In order to save costs, the air heater 1 is preferably an air-to-air heat pump. Such a heat pump gives also the advantage that it can be used to cool air instead of heating air. If such a use is envisaged, channel 2 should preferably be isolated from condensation

The HEPA filter 18 can be a HEPA filter from Camfil AB, Trosa , Sweden, for example a filter with the trade name Megalam MXM HI l 61 x610x90- 10 but other HEPA filters can also be used.

The filter 19 can be a bagfilter from Camfil AB, Trosa , Sweden, with the trade name Hi-Flo XL but other filters of this class can also be used.

The channel 17 leading from the HEPA filter 18 to the mixing chamber is dimensioned so that the pressure drop in this filter will not be too high. Preferably, the diameter of channel 17 should be at least 160 mm.

The embodiment shown in figure 1 can of course be modified within the scope of invention. The channel 14 delivering air from the outside of the building in the mixing chamber can protrude from the rear wall of the mixing chamber instead of passing through the upper wall of mixing chamber. Furthermore, fan 12 can be located in channel 17, i.e. before the mixing chamber 11 instead of after this chamber even if the latter placement is preferred. The air heater need not be a heat pump, even if this is preferred, but can be any type of air heater. The lay-out of the building can be different and more than one channel provided with a HEPA filter can lead to the mixing chamber. The scope of invention shall therefore only be restricted by the content of the enclosed patent claims.

Claims

1. Air cleaning and heating system for a building having several rooms (I- VI) to be heated, said system comprises an air heater (1), means (12) for passing air through said air heater, channels (2,3-8) for leading heated air from the air heater to each said room in said building, a mixing chamber (11) for mixing of air from inside the building and air from outside the building, said chamber being in connection with a channel leading air through said air heater, a channel (14) leading from means (15) for intake of air from outside of the building and having an outlet (13) in said mixing chamber, and means (9,10) for leading used air to the outside of the building, characterized in that the outlet (13) for air from outside the building in said mixing chamber (11) is directed in a direction parallel to the flow direction of the air from the inside of the building in said mixing chamber, and in that a HEPA filter (18) is disposed in an inlet of a channel (17) leading from inside of the building to said mixing chamber.

2. Air cleaning and heating system according to claim 1, wherein said means for passing air through said air heater (1) is a fan (12) disposed downstream of said air heater (1) in a main channel (2) for leading heated air to said rooms (I- VI).

3. Air cleaning and heating system according to claim 1 or 2, wherein said means for intake of air from outside the building is a fan (15) disposed in the channel (14) leading air from outside of the building to the mixing chamber (11).

4. Air cleaning and heating system according to claim 1,2 or 3, wherein a heat exchanger (16) is arranged to preheat air taken from outside of the building with the aid of the used air leaving the building.

5. Air cleaning and heating system according to claim 4, wherein said heat exchanger (16) is a rotary heat exchanger.

6. Air cleaning and heating system according to claim 3, wherein said fan (15) for delivering air from outside of the building to the mixing chamber (11) is controlled to deliver a constant amount of air per unit of time whereas the fan (12) for circulation of the mixture of air from the mixing chamber through the system is variable in dependence of the need for air cleaning.

7. Air cleaning and heating system according to any of claims 1-6, wherein the air heater (1) is an air-to-air heat pump.