Heat exchange – With timer – programmer – time delay – or condition responsive... – Having heating and cooling capability
Reexamination Certificate
1998-11-09
2001-01-23
Ford, John K. (Department: 3743)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Having heating and cooling capability
C165S248000, C165S250000, C165S254000, C165S292000, C165S294000, C165S054000
Reexamination Certificate
active
06176305
ABSTRACT:
This invention relates to ventilator systems and methods, and particularly to ventilator systems and methods using isolating heat exchangers to exchange heat between exhaust air leaving an enclosed space, and outside air entering the building.
It is increasingly common to make modern homes and commercial buildings very air-tight in order to reduce heating and cooling costs. As a result, it has become increasingly necessary to bring fresh air into the building in order to avoid an extreme reduction of oxygen in the building, which can cause the illness or even death of the occupants.
Prior ventilator systems have been designed to use heat exchangers to transfer heat from the exhaust air to the outside air to pre-heat the outside air before it enters the building, thus saving energy and heating costs. This is useful in cold weather when the building must be heated.
In order to protect the health of the occupants, it is very desirable to prevent the air being exhausted from the enclosed space from mingling with the incoming outside air. Thus, often the heat exchangers which are used are those in which the flow of exhaust air is isolated from the flow of outside air through the heat exchanger. These are sometimes called “isolating” heat exchangers.
Other ventilator systems provide for heat transfer from the outside air to the exhaust air when the outside air temperatures are higher than the desired temperatures in the enclosed space. This cools the incoming air before it is further refrigerated to provide the ultimate desired temperature, thus reducing the load on the refrigeration system and reducing the cost of cooling.
Applicant has discovered a problem in that it is believed that prior ventilator systems are not efficiently operable throughout a complete range of outside and inside air temperature conditions. This reduces the utility of the prior ventilator systems and makes them less cost-effective than they might be.
Accordingly, it is an object of the present invention to provide a ventilating system and method in which the foregoing problems are eliminated or alleviated.
More particularly, it is an object of the invention to provide a ventilator system and method which can be utilized for essentially all ventilating conditions, and at essentially all times of the year.
It is an object of the present invention to provide a flexible ventilator system and method in which the mode of operation can be changed readily in response to changing climactic and interior space conditions.
It is a further object of the invention to provide such a system which is relatively inexpensive to manufacture, simple in construction, inexpensive to install and use, and reliable for long-term operation.
In accordance with the present invention, a ventilating system and method are provided in which an isolating heat exchanger is used for recovering energy while supplying outside air to an enclosed space during all weather conditions, by the use of inside and outside air temperature signals.
The invention also provides a ventilating system and method using an isolating heat exchanger in which two different modes of cooling are available; one in which the heat exchanger transfers heat from the incoming outside air to the cooler exhaust air, and another in which heat transfer between the incoming and outgoing air is temporarily eliminated in order to provide supplemental cooling when the outside air temperature is below the desired inside air temperature.
Additional cooling is provided by evaporatively cooling the exhaust air before it reaches the heat exchanger so as to greatly increase the temperature drop of the incoming outside air before it enters the enclosed space.
A further feature of the invention is the provision of a ventilating system and method using an isolating heat exchanger with supplemental cooling, without heat transfer between incoming and outgoing air, as well as heat transfer from the exhaust air to the incoming outside air during cold weather.
Another feature of the invention is the provision of a mode of operation to defrost the heat exchanger. This operation is accomplished by any one or more of the methods of reducing outside air flow; by-passing outside air flow around the heat exchanger; and heating the outside air before it reaches the heat exchanger.
The preferred ventilator system and method use a isolating heat exchanger to selectively transfer heat between exhaust air leaving an enclosed space and outside air entering the enclosed space. The system operates in three basic modes, under the control of a microprocessor-based controller which is responsive to the temperatures inside and outside of the enclosed space. In the heating mode, heat is transferred from the exhaust air to the outside air when the enclosed space requires heating. In the cooling mode, heat is transferred from the outside air to the exhaust air when the outside air temperature is higher than that in the enclosed space. In the supplemental cooling mode, heat transfer between the exhaust and outside air is reduced or eliminated when the outside air temperature is below the desired temperature in the enclosed space and cooling is required. In the heating mode, the heat exchanger is selectively heated when necessary to defrost it. A by-pass is provided for the introduction of outside air in order to avoid heating of the outside air by the exhaust air during the supplemental cooling mode, and/or provide fresh air to the enclosed space without cooling the heat exchanger while it is being defrosted.
The foregoing and other objects and advantages of the invention will be set forth in or apparent from the following description and drawings.
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Yoshino, M. et al. “The Lossnay Penetration Type Total heat Exchanger”Mitsubishi Electric Engineer, Japan, No. 38 (Dec. 1973), pp. 24-27, (copy in 165/54).
“Heat Recovery Ventilators Fresh Air” brochure—NuTone Co.—Cincinatti, OH (no date).
Building Performance Equipment Inc.
Ford John K.
Kramer Levin Naftalis & Frankel LLP
Neff Gregor N.
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