Heat exchange – Regenerator – Movable heat storage mass with enclosure
Reexamination Certificate
1994-10-25
2001-04-03
Atkinson, Christopher (Department: 3743)
Heat exchange
Regenerator
Movable heat storage mass with enclosure
C165S054000, C165S909000, C062S187000, C062S186000
Reexamination Certificate
active
06209622
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to an apparatus for ventilation systems which have means for the transfer of sensible heat and/or water moisture between exhaust air (taken from inside a building) and exterior fresh air (drawn into the building). Such an apparatus may, for example, have means for the transfer of sensible heat and/or water moisture from warm exhaust air to cooler exterior fresh air, the systems using warm interior air as defrost air for defrosting the systems during cool weather.
The present invention, in one particular aspect, relates to an apparatus for ventilation systems which have at least one rotary heat exchanger wheel for the transfer of heat (and/or water moisture) from warm exhaust air (taken from inside a building) to cooler exterior fresh air (drawn into the building).
The present invention, in another particular aspect, relates to a ventilation apparatus for ventilation systems having an exchanger body which may comprise one or more heat exchanger elements of the same or different type e.g. one or more rotary and/or one or more stationary (i.e. non-rotary) exchanger elements or cores.
The present invention, in a further particular aspect, relates to a ventilation apparatus provided with means for balancing fresh air and exhaust air flow through the operating ventilation apparatus; a method for balancing airflow though the apparatus is also provided.
Sensible heat and/or water moisture recovery ventilation systems are known which function to draw fresh exterior air into a building and to exhaust stale interior air to the outside. The systems are provided with appropriate ducting, channels and the like which define a fresh air path and an exhaust air path whereby interior air of a building may be exchanged with exterior ambient air; during ventilation the air in one path is not normally allowed to mix with the air in the other path.
A sensible heat and/or water moisture recovery ventilator device or apparatus, which may form part of a ventilation system, in addition to being provided with corresponding air paths may also be provided with one or more exchanger elements or cores, e.g. one or more rotary and/or stationary (i.e. non-rotary) exchanger elements or cores. Heat recovery ventilation devices may also have a housing or cabinet; such enclosures may for example be of sheet metal construction (e.g. the top, bottom, side walls and any door, etc. may be made from panels of sheet metal). The heat exchanging core(s), as well as other elements of the device such as, for example, channels or ducts which define air paths, filtration means, insulation and if desired one or more fans for moving air through the fresh air and exhaust air paths may be disposed in the enclosure. Such ventilation devices may be disposed on the outside of or within a building such as a house, commercial building or the like; appropriate insulation may be provided around any duct work needed to connect the device to the fresh air source and the interior air of the building. A stationary heat exchanger element(s) may, for example, take the form of the (air-to-air) heat exchanger element as shown in U.S. Pat. No. 5,002,118 the contents of which are incorporated herein by reference. Thus, the heat exchanger element(s) may have the form of a rectangular parallepiped and may define a pair of air paths which are disposed at right angles to each other; these exchanger element(s) may be disposed such that the air paths are diagonally oriented so that they are self draining (i.e. with respect to any condensed or unfrozen water).
Another known type of exchanger element is the rotary thermal and/or desiccant wheel; such (air-to-air) exchanger wheels may have an air permeable heat exchange matrix which provides passageways therethrough through which an air stream may flow. The exchanger matrix may, for example, comprise a plurality of parallel flow channels (see for example U.S. Pat. No. 4,769,053) or even a random matrix media (see for example U.S. Pat. No. 5,238,052). Such exchangers may be configured and disposed such that as they rotate they may transfer a member of the group comprising i) sensible heat and ii) sensible heat and latent heat, between two or more streams of air through which the exchangers rotationally pass through. Such rotary heat exchangers may be disposed in a housing which is suitably baffled such that a rotating exchanger wheel may pass through the fresh air and exhaust air streams with minimal intermixing thereof (i.e. for air-to-air transfer of latent/sensible heat).
Thus, for example, as a suitably configured rotary transfer core slowly rotates between outgoing and ingoing air the higher temperature airstream can give up sensible energy to the core which energy may thereafter be given up by the core to the lower temperature air stream; please see, for example, U.S. Pat. No. 3,844,737. Alternatively, a suitably configured rotary core may capture and release latent energy in the form of water moisture i.e. the core may transfer water vapour or moisture from one air stream to another air stream; please see, for example, U.S. Pat. Nos. 3,800,515, 3,844,737, 4,225,171, and 4,875,520. A rotary energy transfer core or wheel may of course transfer both sensible and latent beat between fresh air and exhaust air; please see, for example, Canadian patent no. 1,285,931, and U.S. Pat. Nos. 4,769,053, 4,172,164,4,093,435, and 5,238,052. The entire contents of the above mentioned patents are herein incorporated by reference.
During the winter season, the outside air is not only cool but it is also relatively dry. Accordingly, if cool dry outside air is brought into a building and the warm moist interior air of the building is merely exhausted to the outside, the air in the building may as a consequence become uncomfortably dry. A relatively comfortable level of humidity may be maintained in a building by inter alia exploiting an above mentioned desiccant type thermal wheel for transferring water from the stale outgoing air to the relatively dry fresh incoming air. During winter these types of heat exchangers may transfer up to 80% of the moisture contained in the exhaust air to the fresh supply air. Advantageously a rotary exchanger wheel may transfer both sensible and latent heat between fresh air and exhaust air; in this case the exhaust air stream as it is cooled may also be dried whereas the incoming fresh air may be warmed as well as humidified. However, a problem with such heat recovery ventilation equipment having a desiccant type heat exchanger wheel, is the production of frost or ice in the air permeable heat exchange matrix of the thermal wheel.
During especially cold weather such as −10° C. or lower (e.g. −25° C. or lower), prior to expelling the relatively warm exhaust air, the equipment provides for the transfer of latent heat from the relatively warm moist exhaust air to the relatively cool dry (fresh) outside air by the use of a suitable desiccant type heat exchange wheel. However, the cooling of the relatively moist interior air by the cold exterior air can result in the formation of ice (crystals). An uncontrolled buildup of ice within the matrix of a rotary exchanger wheel can result in decreased heat transfer, and even outright blockage not only of the exhaust air path but the (cold) fresh air path as well. Accordingly a means of periodically defrosting such a system is advantageous in order to maintain the system's efficiency.
A defrost mechanism has been suggested wherein the fresh air intake is periodically blocked off by a damper and warm interior air is injected, via a separate defrost air conduit, into the fresh air inlet side of the fresh air path of the ventilation apparatus. However, during the defrost cycle, the stale inside air is still exhausted to the outside via the exhaust air path; this is disadvantageous since by blocking only the fresh air inlet and continuing to exhaust interior air to the outside, a negative air pressure can be built up in the interior of a building relative to the exteri
Cusson Pierre
Grondin Jean-Francois
Julien Michel
Lagace Frederic
Marcoux Daniel
Atkinson Christopher
Fay Sharpe Fagan Minnich & McKee LLP
Venmar Ventilation Inc.
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