US3759317A

US3759317A - A heat exchanger

Info

Publication number: US3759317A
Application number: US00169268A
Authority: US
Inventors: Van Diepenbroek A Wibrandt
Original assignee: MORING AND STEENAART; Bronswerk Apparatenbouw BV
Current assignee: MORING AND STEENAART; Bronswerk Apparatenbouw BV
Priority date: 1970-08-10
Filing date: 1971-08-05
Publication date: 1973-09-18
Anticipated expiration: 1990-09-18
Also published as: NL148156B; NL7011801A; DE2139766A1; GB1330744A; JPS545130B1

Abstract

A heat exchanger in which wherein a first fluid flows through heat-exchanging tubes and a second fluid flows around the heatexchanging tubes, one of these fluids being a cooling fluid which withdraws heat from the other fluid, the cooling fluid being a gas supersaturated with water. The cooling fluid is supplied by a device for supersaturating a gas, in particular air, with water.

Description

United States Patent van Diepenhroek Sept. 18, 1973 A HEAT EXCHANGER Inventor: Alfred Erich Wibrandt van Diepenbroek, Ermelo, Netherlands Assignee: N.V. Bronswerk Apparateubouw v/h Moring & Steenaart, Nijkerk, Netherlands Filed: Aug. 5, 1971 Appl. No.2 169,268

Foreign Application Priority Data Aug. 10, 1970 Netherlands 7011801 us. (:1 165/19, 165/60, 165/122 Int. Cl F24f 3/14 Field of Search 165/1, 19, 20, 60,

[56] References Cited UNITED STATES PATENTS 2,129,427 9/1938 Jepertinger 165/20 2,488,636 11/1949 Mendenwall et al. 165/20 Primary Examiner-Charles Sukalo Att0rney-Erich H. Waters et al.

57 ABSTRACT A heat exchanger in which wherein a first fluid flows through heat-exchanging tubes and a second fluid flows around the heat-exchanging tubes, one of these fluids being a cooling fluid which withdraws heat from the other fluid, the cooling fluid being a gas supersaturated with water. The cooling fluid is supplied by a device for supersaturating a gas, in particular air, with water.

3 Claims, 2 Drawing Figures Patented Sept. 18, 1973 A HEAT EXCHANGER BACKGROUND OF THE INVENTION The invention relates to a heat exchanger in which wherein a first fluid flows through heat-exchanging tubes and a second fluid flows around the heat exchanging tubes, one of these fluids being a cooling fluid which withdraws heat from the other fluid.

According to a first known method, a cooling gas, generally outside air, is used as the cooling fluid, the other fluid being lowered in temperature via the wall of the heat-exchanging tubes and/or, if a condensable gas is involved, is condensed as a result of the dissipation of heat.

In this known method the cooling capacity is closely related to the temperature of the cooling gas, i.e., to the temperature of the outside air.

If the required final temperature of the fluid to be cooled difiers only slightly from the temperature of the outside air, the heat exchanger to be used will have to have particularly large dimensions, which, however, is highly uneconomical and will not be feasible in many circumstances.

In these latter cases use is generally made of a further known method wherein cooling water is used as the cooling fluid. This, however, substantially raises the operating costs of the installation, and is not very desirable from the point of view of pollution control.

In view of these drawbacks, use is also made of yet another known method using cooling air which is first passed through a layer of filler material wetted with water, causing the temperature of the air to drop to a value several degrees above the wet bulb temperature.

Although some improvement can be achieved in this manner, the decreased size of the heat exhanger to be used generally does not outweigh the costs and the necessary additional space inherent in these arrangements for obtaining a decrease in the temperature of the cooling air. Accordingly, atmospheric air or water has been used almost exclusively as the cooling fluid.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat exchanger which offers substantial advantages as compared to those specifically of a relatively very small size.

To this end, the invention is characterized in that a gas supersaturated with water is used as the cooling fluid.

The invention specifically proposes the use of a cooling fluid constituted by air supersaturated with water.

A gas supersaturated with water, and specifically air supersaturated with water, contains appreciably more water than the amount of water vapor contained in the gas, specifically air, at 100 percent relative humidity at the same temperature. The excess water forms a mist which is so finely divided as to follow the flow of gas (air) entirely.

Not only does the supersaturation with water cause the inlet temperature of the cooling gas to be lowered, but it causes this lower cooling-gas temperature to be maintained for a longer period of time.

Further, it has surprisingly been found that the coeffi cient of heat transfer between the cooling gas supersaturated with water, generally cooling air supersaturated with water, and the heat-exchanging tubes is appreciably increased due to the presence of the mist of water.

The probable cause of this phenomenon is an evaporation in this mist of water resulting from the flow of the cooling gas along the heat-exchanging tubes, producing such turbulence in the immediate vicinity of the heat exhanging tubes as to break the boundary layer, thus removing the adverse effect thereof upon the coefficient of heat transfer.

According to the invention, the size of the heat exchanger can be substantially reduced, resulting in great savings of costs and floor space, while a lower final temperature of the fluid to be cooled can be attained.

Furthermore, on account of the small size of the heat exchanger, the danger of freezing occurring in the known air-cooled heat exchangers is greatly reduced.

This heat exchanger is characterized in that the cooling fluid is supplied by means for supersaturating a gas, in particular air, with water.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will hereinafter be further explained with reference to the drawing, which shows an embodiment of the heat exchanger according to the invention, by way of example, and wherein:

FIG. 1 is a longitudinal section of an embodiment of the heat exchanger according to the invention; and

FIG. 2 is a cross section taken on line IIII in F IG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT The drawing shows a heat exchanger comprising a purality of heat exchanging tubes 1, which bear outer ribs 2, mounted in a frame 3. This frame 3 comprises a supply distribution chamber 4 and a discharge chamber 5 therebelow on one side and a reversing chamber 6 on the opposite side.

The fluid to be cooled and/or to be condensed passes through theinlet 7 into the supply distribution chamber 4 and flows through the upper row of heat-exchanging tubes 1, whereupon the direction of flow is reversed in the reversing chamber 6 and the lower row of heatexchanging tubes 1 is traversed. The cooled and/or condensed fluid then reaches the discharge chamber 5 and is discharged through the outlet 8.

The frame 3 is supported by posts9 and is connected at its lower end to a funnel-shaped receptacle 10 which has an opening 11 in its bottom, wherein are positioned the outlets of two atomizing blowers 12 for supersaturating air with atomized water. These blowers 12 are mounted side by side and may be of the type, for example, as described in British Patent Specification No. 750,559.

The atomizing blowers 12 are each driven by a belt 13 from an electric motor 14. The outside air is sucked, through intake openings 15 located on either side of each atomizing blower 12, into the blowers 12, where the air is supersaturated with water. To this end, water is sprayed under pressure through sprayers 16 disposed at the intake openings 15 of the blowers 12. This water is broken up to form a fine mist due to the special design of the impeller and the use of further provisions made in the blower casing. This mist is entrained by the current of air that emerges from the atomizing blowers 12. The water is fed to the sprayers 16 from a pipe 17 which contains a control cock 18. The water not taken along by the current of air can be drained from the atomizing blowers 12 through outlet pipes 19.

Of course, use may be made of other devices for supersaturating air with water. Examples of these include atomizing sprayers based on centrifugal force, pressure-atomizing systems, or electrical vaporizing systems.

The supersaturated air flows around the heatexchanging tubes 1, causing heat to be withdrawn from the fluid to be cooled which flows through the heatexchanging tubes 1.

The outside air which is supersaturated with water possesses a temperature equal to the wet bulb temperature, which it retains for a prolonged period of time, despite the absorption of heat via the heat-exchanging tubes 1, because the mist of water evaporates in whole or in part. The presence of the mist of water in the cooling air furthermore produces an increase in the coefficient of heat transfer, as explained hereinabove.

The absorption of heat by the supersaturated air while passing around the heat-exchanging tubes 1 can be very simply controlled by adjusting, with the aid of the control cock 18, the amount of water supplied per unit time, and thus the degree of supersaturation of the cooling air. The heat exchanger can thus be adapted to the prevailing load.

The heat exchange can furthermore be regulated by changing the supply of air to the atomizing blowers 12, for example with the use of valves, or of whirl control, or of an adjustment of the speed of rotation of the impeller.

The supply of the fluid to be cooled to the inlet 7 naturally can also be made adjustable by using a bypass with an adjustable passage.

A small portion of the water entrained by the cooling air can fall downwardly during the passage of the cooling air from the atomizing blowers 12 to the heatexchanging tubes 1 as well as in the course of passing these heat-exchanging tubes 1. In such case, this water is collected in the funnel-shaped receptacle and is fed back to the atomizing blowers 12, where the water can flow away through the outlet pipes 19. Where required, the water discharged through the outlet pipes 19 can be recirculated at least in part. Also, at least part of the cooling air, having passed the heatexchanging tubes 1, can be collected and recirculated.

The invention is not restricted to the embodiment illustrated in the drawing, which may be varied in different manner within the scope of the invention. It is possible, for example, to use only one atomizing blower 12, or more than two atomizing blowers, while the heatexchanging tubes 1, which are horizontal in the embodiment shown, can also be arranged in vertical or inclined positions.

Further, the supersaturated air can flow through rather than around the heat-exchanging tubes 1, in which case these heat-exchanging tubes 1 are preferably provided with internal ribs. in such case, the fluid which is to be cooled flows around the heat-exchanging tubes 1.

I claim:

1. A heat exchanger, comprising heat-exchanging tubes, means for supplying a first heated fluid to said tubes for flow therethrough, means for circulating a second cooling fluid around said heat-exchanging tubes, the means for supplying said cooling fluid including means for supersaturating air with water including means for inducing a flow of air to said tubes and means for finely dividing the water to follow the flow of air entirely, said means for inducing a flow of air to said tubes comprising a blower having air inlets at opposite ends thereof and an outlet facing said tubes, said means for finely dividing the water comprising sprayers located at said inlets and facing inwardly into said blower for spraying the water under pressure thereinto, said blower including an impeller facing said sprayer to break the water into a mist which is entrained in entirely in the air in superstiturated state.

2. A heat exchanger according to claim 1 wherein said air supersaturated with water flows around the heat-exchanging tubes, and comprising drainage means for water located below the means for supersaturating air with water.

3. A heat exchanger according to claim 1 wherein the means for supersaturating air with water comprises a control member for regulating the supply of water.