Heat exchange – Movable heating or cooling surface – Rotor carrying separate chambers for two exchanging fluents
Reexamination Certificate
2002-07-15
2004-02-24
Flanigan, Allen (Department: 3743)
Heat exchange
Movable heating or cooling surface
Rotor carrying separate chambers for two exchanging fluents
C165S164000, C416S184000
Reexamination Certificate
active
06695038
ABSTRACT:
FIELD OF THE INVENTION
The claimed invention belongs to heat exchange devices where the heat carriers do not mix, and may be used, for instance, in ventilation and air conditioning systems for heat exchange between the intake and the exhaust air streams.
BACKGROUND OF THE INVENTION
A heat exchanger type fan is known, described in a Japanese application 60-75634, (Int. Cl. F 28 D 9/00, Filed Oct. 4, 1985, Publ. Date Jun. 7, 1994), consisting of a casing and two centrifugal fans mounted on the same shaft inside the casing but oriented in opposite directions in regard to each other. Two channels for heat carriers (air streams) of different temperature are formed in the casing, separated by a heat exchange element made as a corrugated radial partition installed beyond the edges of the impellers of the fans and equipped with a disk to separate the fans. When the fans rotate, the heat carriers enter the space between the blades of the fans and further on, passing over the corrugated radial partition of the heat exchange element on both sides, are removed from the casing via the respective blower outlets. Heat exchange takes place through the corrugated partition while the heat carriers pass over its faces. A big radial size should be listed among the disadvantages of such arrangement.
A heat exchanger type fan is known, described in a Japanese application 60-75635 (Int. Cl. F 28 D 9/00, Filed Oct. 4, 1985, Publ. date Jun. 7, 1994), consisting of a casing and two centrifugal fans mounted on the same shaft inside the casing, but oriented in opposite directions in regard to each other. Two channels for heat carriers of different temperature are formed in the casing, separated by a partition separating also both fans. The heat exchange element is made as radial fins mounted on both surfaces of the partition beyond the edges of the impellers of the fans. When the fans rotate, the heat carriers enter the interblade space of the fans via the suction inlets and further on, passing over both sides of the radial fins of the heat exchange element, are removed from the casing via the respective blower outlets. Heat exchange takes place through the radial fins and the partition itself Again a big radial size should be listed among the disadvantages of such arrangement.
The closest to the claimed invention is the heat exchanger type fan described in the Japanese application 61-86463 (Int. Cl. F 28 D 11/02, Filed Apr. 15, 1986, Publ. date Jan. 6, 1994), consisting of a casing and an impeller of a double-sided centrifugal fan made as a radially corrugated disk with an outer rim, the faces of the corrugation performing the function of radial blades. There is a partition in the casing adjoining the outer rim of the impeller and dividing the casing into two isolated chambers (channels) for heat carriers (air streams) of different temperature. Owing to this partition, there are two isolated centrifugal fans formed inside the casing with a single double-sided impeller. When the impeller rotates, the heat carriers enter the interblade space of the fans via the respective suction inlets and further on are removed from the casing via the respective blower outlets. Under such arrangement heat exchange takes place through the radial faces of the corrugated impeller.
In the known heat exchanger type fan the impeller, being the heat exchange surface at the same time, is formed by a radially corrugated surface. Such impeller design results in its low efficiency both as a part of a centrifugal fan and as a heat exchanger.
The former is explained by the fact that it is the radially corrugated surface that performs the function of the blades. In this case the air stream outgoing from the impeller of the fan has a surplus pressure exceeding that necessary pressure to overcome the total hydraulic resistance of the fan. This will require more power to be supplied. To eliminate this feature, characteristic of centrifugal fans with radial blades, blades of a different shape are required, namely backward-curved blades. It is obvious that manufacturing a corrugated disk with bent blades presents a rather difficult engineering problem. The curvature of such corrugation will be determined by the permissible plastic deformation of the material the impeller is made of With this the properties of the material will be in contradiction with the required rigidity of the impeller experiencing a considerable action of centrifugal forces during operation. This contradiction results in it being impossible to manufacture a corrugated disk with the degree of the blade curvature being great enough. Therefore with such arrangement it will be impossible to eliminate the surplus pressure and to reduce the amount of power to be supplied.
The low heat exchange efficiency of the known device is explained by the following. The heat exchange efficiency is to a certain extent influenced by both the area of the heat exchange surface and the rate at which the heat carrier passes over it. With radial blades, firstly, the area of heat exchange will be at its minimum, since the radial blades are of minimum length, and, secondly, the rate at which the heat carrier passes over that area will decrease towards the periphery of the impeller, which is caused, taking into account the continuity of the air stream, by the fact that the cross-section area of the interblade space increases towards its periphery. Thus, notwithstanding that the area of heat exchange is comparatively large, its efficiency is not going to be high.
Another factor behind the low efficiency of heat exchange is the direct-flow process implemented in the device where both heat carriers flow unidirectionally: in the known device they flow from the center to the periphery of the impeller. Whilst it is known that a better heat exchange efficiency can be achieved if the counter-flow pattern is used where the heat carriers flow in opposite directions. In regard to the known device this means that one of the impeller sides should work as a centripetal one. However, it is not possible with radial blades, and manufacturing a corrugated disk with bent blades, as it was already mentioned, presents a fairly complicated engineering problem, and, bearing in mind that the shape of the blades on both sides will be different, it will be impossible to make the impeller as a corrugated disk.
SUMMARY OF THE INVENTION
The engineering problem at the solution whereof the claimed invention is aimed, is to increase the efficiency of heat exchange and to lower the power consumption. Three embodiments of the solution for the stated problem are claimed.
The essence of the claimed invention according to the first embodiment consists in that in a heat exchanger type fan comprising a casing and an impeller of a double-sided centrifugal fan mounted in it, the casing being divided into two isolated chambers which, together with the impeller, form two isolated centrifugal fans, in accordance with the invention the impeller is made as a solid dividing disk on both sides whereof blades are made normal to its plane, said blades being bent backwards (backward-curved).
Replacement of the corrugated impeller disk with a solid disk with the blades made normal to its surface on both its sides will allow for the manufacturing of the blades of any desired curvature, such arrangement being no longer dependent on the manufacturing technology for the corrugated surface. The fact that the blades are made bent backwards permits to make the surplus pressure at the outlet of the centrifugal fan considerably lower, thus reducing the amount of power consumed. Changing the curvature of the blades it becomes possible to change the cross-section area of the interblade space normal to the blades, to seek for the constant rate of the airflow passing over the blade surfaces. Manufacturing the blades this way, as distinct from the known one, will make it possible to considerably increase both the number of the blades and “the density of the impeller blade spacing”, that is, the ratio of the blade length to the distance between the blades on t
Fedoseyev Lev A.
Fedosov Yuriy Igorevich
Gerasimov Oleg Mikhailovich
Lopatinsky Edward
Popov Victor Nikitovich
Advanced Rotary Systems LLC
Flanigan Allen
LandOfFree
Heat exchanger type fan does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat exchanger type fan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat exchanger type fan will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3346732