WO2016016777A1

WO2016016777A1 - Ventilation system and components thereof

Info

Publication number: WO2016016777A1
Application number: PCT/IB2015/055573
Authority: WO
Inventors: Jacobus Johannes SWIEGERS
Original assignee: Stellenbosch University
Priority date: 2014-07-29
Filing date: 2015-07-23
Publication date: 2016-02-04

Abstract

A ventilation inlet is provided for an enclosed space that may be convertible between a ventilation inlet and a ventilation outlet configuration. An elevated wind operated turbine is coupled to a fan so that it rotates in direct response to rotation of the turbine. The fan is arranged within a duct and is configured to move air within the duct downwards or upwards towards or away from a lower air discharge opening. A single duct communicates between an elevated air inlet and a lower air discharge opening. A natural ventilation system is also provided in which an enclosed space has an air inlet provided with such an air inlet and an air outlet is provided such that air entering by way of the air inlet passes through the enclosed space flowing from the air discharge opening to the air outlet.

Description

VENTILATION SYSTEM AND COMPONENTS THEREOF

CROSS-REFERENCE(S) TO RELATED APPLICATIONS

This application claims priority from South African provisional patent application number 2014/05574 which is incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to a ventilation system and components thereof and, more particularly, but not exclusively, to a natural circulation ventilation system that is generally independent of any energy input other than renewable energy.

More particularly, but not exclusively, the invention relates to a ventilation system in which a flow of air through an enclosed space is created using primarily renewable energy. BACKGROUND TO THE INVENTION

It is well known to use so-called wind activated turbines, in some instances operating in conjunction with the so-called chimney effect, in order to remove stale or hot air from a particular enclosed habitable space. As far as applicant is aware, such wind activated turbines are, at least for the most part, employed solely to remove stale and hot air with replacement air being drawn in by way of separate air inlets.

There have, however, been proposals such as that contained in published United States patent application US 201 10201264 to employ a combination unit that has both an air inlet and an air outlet that are separated from each other but present in a single unit and has a heat exchanger for conserving heat in outlet air by transferring it to fresh incoming air or vice versa. The proposal is somewhat complex and the applicant it is not aware of any commercial turbine operated product that is available that can do this effectively. There is an ongoing international movement towards making, in amongst others, ventilation systems as independent as possible from of the input of energy that has any significant carbon footprint such as, for example, electricity that is generated using coal or gas fired boilers. There is a move towards what may be termed passive housing that, at least from the point of view of temperature control of the habitable space, requires little or no energy input over a one-year period. However, many of the proposals that have been put forward and that are currently being tested are very expensive and are aimed primarily at maintaining warmth in a building that is located in a generally cold climate.

As far as ventilation is concerned, part of this movement that is aimed at what is termed natural ventilation that means that the ventilation of a building does not involve the use of any equipment or processes that require the use of energy derived from fossil fuels or any other source that leaves a significant carbon footprint. The energy consumption of traditional heating, ventilation and air conditioning (HVAC) systems is avoided There is scope for alternative ventilation systems that may be appropriate to particular types of climate and that are not highly sophisticated and costly.

The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.

SUMMARY OF THE INVENTION In accordance with one aspect of this invention there is provided a ventilation inlet for an enclosed space wherein the ventilation inlet is optionally convertible between a ventilation inlet and a ventilation outlet configuration, the ventilation inlet having an elevated wind operated turbine and a single duct communicating between an elevated air inlet and a lower air discharge opening and wherein a fan is coupled to rotate in direct response to rotation of the turbine with the fan being arranged within the duct and being configured to move air within the duct downwards towards the lower air discharge opening.

Further features of the invention provide for the wind operated turbine to be a vertical axis wind turbine such as those known as Savonius, Darrieus, and Giromill turbines, cycloturbines as well as modified types of vertical axis wind turbines having helically extending blades or blades following an otherwise twisted path that serves to even out torque developed over a revolution of a vertical axis wind turbine; for the wind turbine to have two, three, four or more blades each of which may present a concave face and a convex face or may be of aerofoil shape in cross- section; for the fan to be either secured to a shaft rotated directly by a vertical axis wind turbine so that it rotates in unison therewith or for the fan to be coupled to the turbine by way of gears providing for a reduction or increase in the speed of rotation of the turbine; for fixed generally upright wind deflectors to project obliquely in plan view outwards from the vertical axis wind turbine such that they are orientated to deflect wind towards the blades of the vertical axis wind turbine; for an evaporative cooling assembly to be installed within the duct or in-line with the duct such that air passing through the duct toward the lower air discharge opening may, in the presence of water, be subjected to evaporative cooling; and for the wind turbine and fan to be vertically spaced to provide for free flow of air into the single duct with the turbine causing minimal obstruction to air flow.

In accordance with a second aspect of the invention there is provided a natural ventilation system associated with an enclosed space wherein an air inlet to the enclosed space is provided with an air inlet as defined above and an air outlet from the enclosed space is provided such that air entering by way of the air inlet passes through the enclosed space in flowing from the air inlet to the air outlet.

Further features of the second aspect of the invention provide for the air outlet to be solar assisted by virtue of a solar chimney having a suitable surface directed in the general direction of sunshine; and for the air outlet to be fitted with a wind operated turbine assembly of the general nature defined above in its outlet configuration so that the turbine fan moves air up and out of the outlet.

In order that the above and other features of the invention may be more fully understood one embodiment of the invention will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:-

Figure 1 is a three-dimensional illustration showing a vertical axis wind turbine in the form of a Savonius wind turbine that was used for test purposes on the outside of a roof;

Figure 2 is an offset underneath three-dimensional illustration of the Savonius wind turbine and fan assembly;

Figure 3 is an exploded three-dimensional illustration of the Savonius wind turbine and fan assembly;

Figure 4 is a schematic elevation of an inlet according to the invention including an evaporative cooling assembly; Figure 5 is a schematic illustration of an enclosed space in the form of a habitable room ventilated by means of the ventilation system provided by the invention;

Figure 6 is a graph showing the volumetric flow rate of air in an inlet at two different conditions; and,

Figure 7 is a graph showing the variation in temperature at different points in the inlet under different wind conditions.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

In the embodiment of the invention illustrated in the drawings, a ventilation inlet for an enclosed space comprises a vertical axis wind turbine in the form of a Savonius wind turbine (1 ) having four equally angularly spaced upright curved blades each of part circular shape, in this instance semi-circular shape, in horizontal cross-section so as to present a vertically extending concave face (2) on one side thereof and a convex face (3) on the other side thereof. The concave faces of all of the curved blades face in the same angular direction relative to an axis of rotation of a vertical central shaft (4) of the turbine blade assembly, as will be quite apparent to those of ordinary skill in the art. Of course the actual construction of the vertical axis wind turbine is not of any consequence and the Savonius wind turbine has a construction that is favourable towards the production of prototypes. Any other type of wind turbine can be used as will be quite clear from what is stated above. Especially, the blades could follow a generally helical or twisted path. Thus, the upright semi-circular cross-sectioned shape could be bent to form a helical semi-circular shape which could be employed to assist in pushing air into, or pulling air out of, an open end of a duct, depending of the angle of bend.

Four relatively stationary generally flat upright, or otherwise appropriately shaped, wind deflectors (5) project obliquely in plan view from a frame (6) of the vertical axis wind turbine such that they are orientated to deflect wind towards, in this instance, the concave faces of the curved blades. The arrangement is such that wind is channelled towards the concave faces of the curved blades to enhance the effect of the wind on the blades. The structure described above may be made from aluminium, which is light in weight and will not put undue strain on a roof structure. Alternatively, it may be made of a suitably strong stainless steel or even a suitably strong and durable plastic composite. The ventilation inlet assembly may consist of few components and may be designed to be easy to assemble and disassemble.

The ventilation inlet thus has an elevated vertical axis wind turbine mounted, for example, on a roof (7), or alternatively at the top of a chimney, and a single duct (8) communicates between the turbine at an upper air and a lower air discharge opening (9). The vertical axis wind turbine has a round roof (10) to protect the assembly against rain. Alternatively, any other structure effective to combat rain may be used. A fan (12) is rotatable by the vertical axis wind turbine, in one instance by being secured to a common shaft rotated directly by the turbine so as to be rotatable in unison with fan and the turbine shaft. Alternatively, the fan may be coupled to the turbine by way of gears providing for a reduction or increase in the speed of rotation with the fan being arranged within the duct (8) and being configured to move air within the duct downwards towards the lower air discharge opening (9). This is contrary to the usual arrangement in which, the unlikely event that a fan is attached to be driven by a wind turbine, the turbine is used exclusively for exhausting hot or stale air from a space and therefore moving air in an opposite direction to that proposed by this invention. An evaporative cooling assembly (13) (see Figure 4) is installed within the duct, or in-line with the duct, such that air passing through the duct may, in the presence of water, be subjected to evaporative cooling. An evaporation cartridge used for this purpose may consist of concentric evaporator pads (14) which are held in position relative to each other by steel wiring. The cartridge may be wetted with water from a reservoir (15) that could be fitted onto a roof of a chosen building in which the system is installed. The reservoir could be filled with rain water or by a natural water pump or by a conventional water pump (not shown).

Turning now to the second aspect of the invention, and with particular reference to Figure 5, there is provided a natural ventilation system associated with an enclosed space (21 ) wherein an air discharge opening (9) to the enclosed space is associated with an air inlet as described above. An air outlet (23) from the enclosed space is provided at a position removed from the air inlet such that air entering by way of the air discharge opening (9) must pass through the enclosed space in flowing from the air discharge opening (9) to the air outlet. The air outlet may be solar assisted by virtue of a solar chimney (24) having a suitable external surface (25) directed in the general direction of the usual source of sunshine. In the northern hemisphere such a direction would be generally south and in the southern hemisphere would be generally north. The air outlet is preferably fitted with a wind operated turbine assembly (26) of the general nature described above but converted to its outlet configuration so that the fan moves air up and out of the outlet rather than downwards and into the enclosed space. This can be achieved simply by reversing the inclination of the fan blades. Alternatively, it can be achieved using the same fan and reversing the angular direction in which the curved Savonius turbine blades and the wind deflectors are directed so that the direction of rotation is reversed. In use, air enters the air inlet; passes through the evaporative cooler; and enters the enclosed space. It passes through the enclosed space and out through the outlet. Whilst this takes place, the fan in conjunction with the vertical axis wind turbine increases volumetric flow rate of air through the inlet and into the enclosed space. It is to be noted that an increased volumetric flow rate is often required in natural circulation ventilation systems as buoyancy forces alone may be insufficient to reach a required volumetric flow rate for the recommended changes of a volume of air within the enclosed space within a particular period of time. The turbine fan inlet configuration has been designed with natural ventilation systems in mind. Natural ventilation systems generally have slower moving air, when compared with conventional heating, ventilation and air conditioning (HVAC) systems, because it uses, at least to some extent, buoyancy effects to move air through an enclosed living space. In use when the evaporative cooler is functional, water is evaporated from the evaporator cartridge that is situated in what may be considered as a passive downdraught evaporative cooling (PDEC) duct. The cartridge may be made from 100% cotton, because of its wettability. Evaporation from the cartridge to surrounding air increases the relative humidity and decreases the dry bulb temperature. The colder air tends to sink down the downdraught evaporative cooling shaft. The volumetric flow rate of air moving through the downdraught evaporative cooling duct is dependent on the availability of water and would therefore be zero if no water is available and the Savonius wind turbine is inoperative due to there being an absence of wind. Most commonly there would be a combination effect. On the opposite side of the enclosed living space is the solar chimney in which solar radiation warms air in the solar chimney, which starts flowing upwards as a consequence. This upwards moving air may be slow moving and the outlet configuration of the vertical axis wind turbine tends to urge air up the solar chimney and out from the enclosed space. Test results of a Savonius wind turbine assisted inlet chimney which is a natural circulation ventilation system as described above are shown in Figures 6 and 7. Results were obtained using T-type thermocouples and an Agilent data logger in various tests exposing the turbine fan inlet configuration to a variety of operating conditions. Figure 6 is a set of graphs showing the volumetric flow rate of air over a range of different wind speeds for a simple open ended chimney; a chimney fitted with the turbine fan inlet according to the invention with the evaporative cooler in a dry condition; and a chimney fitted with the turbine fan inlet according to the invention with the evaporative cooler in a wetted condition. The volumetric flowrates and temperature distribution of the tests were conducted at T_amb=27°C; relative humidity = 45.8%; and Pabs = 99,8 kPa.

Figure 7 is a set of graphs showing the temperature of the air at four different measurement heights up the chimney for four different wind speeds with the evaporative cooler in a wetted condition. These tests were also conducted at T_amb=27°C; relative humidity = 45.8%; and Pabs = 99,8 kPa.

It will be understood that numerous variations may be made to the embodiment of the invention described above without departing from the scope hereof.

Throughout the specification and claims unless the contents requires otherwise the word 'comprise' or variations such as 'comprises' or 'comprising' will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

CLAIMS:

1 . A ventilation inlet for an enclosed space wherein the ventilation inlet is optionally convertible between a ventilation inlet and a ventilation outlet configuration, the ventilation inlet having an elevated wind operated turbine and a single duct communicating between an elevated air inlet and a lower air discharge opening and wherein a fan is coupled to rotate in direct response to rotation of the turbine with the fan being arranged within the duct and being configured to move air within the duct downwards towards the lower air discharge opening.

2. A ventilation inlet as claimed in claim 1 in which the wind operated turbine is a vertical axis wind turbine selected from a Savonius, a Darrieus, and a Giromill turbines, and cycloturbines including modified types of vertical axis wind turbines having helically extending blades or blades following an otherwise twisted path that serves to even out torque developed over a revolution of a vertical axis wind turbine.

3. A ventilation inlet as claimed in either one of claims 1 or 2 in which the wind turbine has two, three, four or more blades each of which may present either a concave face and a convex face or may be of aerofoil shape in cross-section.

4. A ventilation inlet as claimed in any one of the preceding claims in which the fan is secured to a shaft rotated directly by a vertical axis wind turbine so that it rotates in unison therewith.

5. A ventilation inlet as claimed in any one of claims 1 to 3 in which the fan is coupled to the turbine by way of gears providing for a reduction or increase in the speed of rotation of the fan.

6. A ventilation inlet as claimed in any one of the preceding claims in which fixed generally upright wind deflectors project obliquely in plan view outwards from a vertical axis wind turbine such that they are orientated to deflect wind towards the blades of the vertical axis wind turbine.

7. A ventilation inlet as claimed in any one of the preceding claims in which an evaporative cooling assembly is installed within the duct or in-line with the duct such that air passing through the duct toward the lower air discharge opening may, in the presence of water, be subjected to evaporative cooling.

8. A ventilation inlet as claimed in any one of the preceding claims in which the wind turbine and fan are vertically spaced to provide for free flow of air into or out of the single duct with the turbine causing minimal obstruction to air flow.

A natural ventilation system associated with an enclosed space wherein an air inlet to the enclosed space is provided with an air inlet as claimed in any one of the preceding claims and an air outlet from the enclosed space is provided such that air entering by way of the air inlet passes through the enclosed space in flowing from the air inlet to the air outlet.

A natural ventilation system as claimed in claim 9 in which the air outlet to be solar assisted by virtue of a solar chimney has a suitable surface directed in the general direction of sunshine.

A natural ventilation system as claimed in either one of claims 9 or 10 in which the air outlet is fitted with a wind operated turbine assembly as claimed in any one of claims 1 to 8 in its outlet configuration so that the turbine fan moves air up and out of the outlet.