Device and method for minimizing the effect of ambient conditions on the operation of a heat exchanger

Abstract

A heat exchanger system for cooling liquid having a plurality of finned tube arrays and a plurality of fans for inducing air through the finned tube array comprising: at least one wind deflector installed along the long side of the finned tube arrays on at least one side of the arrays. The present invention for includes a method for minimizing the undesired effect of wind on the operation of a heat exchanger system for cooling liquid having a plurality of finned tube arrays and a plurality of fans for inducing air through the finned tube array, the method comprising the steps of: setting the angle of deflection of the wind deflectors other than the angle of deflection of the uppermost position of the wind deflectors; collecting readings of outlet temperature sensor of the heat exchanger, ambient temperature, wind sensor and inlet air pressure sensor of the heat exchanger; recording readings of outlet temperature sensor of the heat exchanger, ambient temperature, wind sensor and inlet air pressure sensor of the heat exchanger; comparing readings of outlet temperature sensor of the heat exchanger, ambient temperature, wind sensor and inlet air pressure sensor of the heat exchanger to previous readings; and carrying out a correction command if the readings have changed.

Claims

1. A heat exchanger system for cooling liquid, comprising: a heat exchanger having generally rectangular arrangement of a plurality of horizontally spaced finned tube arrays arranged above the ground for cooling fluid flowing in finned tubes of said plurality of horizontally spaced finned tube arrays, the arrangement having longer sides extending in a length direction and shorter sides extending in a width direction; a plurality of fans provided above the finned tube arrays for inducing air through the finned tube arrays, wherein at least two of said fans are mutually spaced in the width direction; and at least one wind deflector installed directly on the ground and having a portion located at ground level at a location directly vertically below one fan of said plurality of fans, and separate from any portion of said heat exchanger having said generally rectangular arrangement of a plurality of horizontally spaced finned tube arrays, wherein said at least one wind deflector diverts wind flowing in an approximately horizontal direction below said heat exchanger to instead flow in a direction that is more vertically upward and toward the axis of at least one of the plurality of fans, so that the fluid flowing in the finned tubes of said plurality of horizontally spaced finned tube arrays is cooled, wherein said at least one wind deflector is installed at a location directly vertically below said one fan of said plurality of fans such that a vertical line intersecting the axis of said one fan also intersects said portion of said at least one wind deflector.

2. The heat exchanger system according to claim 1, wherein said plurality of fans comprises an array of three fans mutually spaced in the width direction, said three fans comprising an end fan at an end of said array in the width direction, and wherein said least one wind deflector has a portion located at ground level at a location directly vertically below said end fan of said plurality of fans.

3. The heat exchanger system according to claim 1, wherein said plurality of fans comprises an array of three fans mutually spaced in the width direction, said three fans comprising a middle fan at the middle of said array in the width direction, and wherein said at least one wind deflector has a portion located at ground level at a location directly vertically below said middle fan of said plurality of fans.

4. The heat exchanger system according to claim 1, wherein the angle of said wind deflector to the horizontal direction is zero when no wind is present.

5. The heat exchanger system according to claim 1, further comprising a sensor located near the outlet of said plurality of fans.

6. The heat exchanger system according to claim 5, wherein said sensor is a temperature sensor located adjacent an outlet of said plurality of fans, for measuring the temperature at the outlet of said plurality of fans.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

(2) FIG. 1A depicts heat exchanger as is known in the art;

(3) FIGS. 1B and 1C schematically depict cross section in heat exchanger;

(4) FIG. 1D is a graph depicting the amount of air flow through each one of three fans in a row in an array across the width dimension of a heat exchanger;

(5) FIG. 1E represents the temperature distribution in the air above three fans when strong wind blows over the heat exchanger;

(6) FIG. 2 depicts a system for minimizing ambient effect on the operation of heat exchanger according to embodiments of the present invention;

(7) FIGS. 3A, 3B, 3C and 3D present heat exchangers in four different working conditions, as a function of the wind, according to embodiments of the present invention;

(8) FIG. 3E presents a heat exchanger having means for diverting the wind for minimizing ambient effect on the operation of heat exchanger according to a further embodiment of the present invention;

(9) FIG. 3F presents an embodiment of the means for diverting the wind for minimizing ambient effect on the operation of heat exchanger shown in FIG. 3E according to the present invention;

(10) FIGS. 3G and 3H present other embodiments of the means for diverting the wind for minimizing ambient effect on the operation of heat exchanger shown in FIG. 3E according to the present invention;

(11) FIG. 3I presents a heat exchanger having further means for diverting the wind for minimizing ambient effect on the operation of heat exchanger according to a still further embodiment of the present invention; and

(12) FIG. 4 is a flow diagram presenting a method of operation of a system according to embodiments of the present invention.

(13) It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION

(14) In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

(15) A heat exchanger is disclosed, according to embodiments of the present invention, equipped with one or more wind deflectors, to affect the flow of air under finned tube sections of a heat exchanger so as to minimize, and even completely cancel that undesired effect of the blowing wind.

(16) Reference is made now to FIG. 2, depicting system 200 for minimizing ambient effect on the operation of heat exchanger 201 according to embodiments of the present invention. Heat exchanger 201 can comprise a plurality of finned tube arrays 202 equipped with a plurality of fans 204 adapted to induce air through finned tube arrays 202. The plurality of finned tube arrays 202 and plurality of fans 204 are installed so that their width dimension W and length dimension L form a plane that is essentially horizontal. The finned tube arrays 202 are installed above the ground/floor by FH to allow free flow of air under finned tube arrays 202. System 200 may further comprise a plurality of wind deflectors 208, installed along the long sides of the finned tube arrays on both sides of the arrays. Wind deflectors 208 are installed pivotally on finned tubes arrays 202 so as to allow wind deflectors 208 to change the angle . between wind deflector 208 and support legs 209 of finned tubes arrays between 0 degrees and essentially 180 degrees.

(17) Wind deflectors 208 can be driven by actuators 220 to control their actual deflection angle . Actuators 220 may be an electrical motor, a hydraulic motor, a pneumatic motor or any other control that may change the deflection angle . in a controllable manner. According to some embodiments of the present invention, actuator 220 can comprise, or be coupled to, an angle indicator (not shown) or other indicator, such as a shaft encoder, either absolute or relative, to provide indication of the actual angle of wind deflectors 208.

(18) System 200 may further comprise temperature sensors 210 located at the outlet of some of fans 204, advantageously sensing the temperature of the air at the outlet of pairs of fans 204 located in the same row (a row being parallel to the width dimension) at the outer ends of the row and, each, next to a respective edge of finned tube arrays 202. System 200 may further comprise ambient conditions sensor 212, which may comprise temperature sensor, wind direction and speed sensor, and the like. Ambient conditions sensor 212 should preferably be located far enough from heat exchanger 201, to avoid influence of the activity of heat exchanger 201 on the operation of ambient sensor 212.

(19) Some embodiments of system 200 may further comprise one or more pressure sensors located under finned tubes arrays 202 (see in FIG. 3A, units 318), used to sense the pressure near the entry of cooling air into heat exchanger 201. The pressure sensors may be adapted to sense static pressure, dynamic pressure or both. Indication received from these sensors may be meaningful for identifying development of conditions leading to turbulent flow of the cooling air, while it is apparent that the heat dissipation of heat exchanger 201 grows when the cooling air flow is laminar.

(20) System 200 further comprise controller 230 to receive readings from the various sensors and to control the actual deflection angles of wind deflectors 208. Controller 230 may be a computer, a controller, a programmable logic controller (PLC) and the like. Controller 230 may comprise an input/output (I/O) unit, a non-transitory memory storage unit to store programs, data and tables of stored variables and communication interface unit to allow communication with other controllers and/or with a control center.

(21) The control of the actual deflection angles of wind deflectors 208 may be responsive to changes in one or more of the various measured parameters received from the various sensors, as presented, for example, in the following chart.

(22) TABLE-US-00001 Parameter Effect on Deflection Angle 1 Wind direction within limits of Control system active angle 2 Wind direction is out of limits Control system inactive; wind of angle a and/or wind speed is deflectors are placed in their close to zero uppermost position ( = 150-180 degrees) 3 Temperature difference T1 Decrease angle of the wind between a pair of temperature deflector close to the temperature sensors (210) is growing sensor sensing lower temperature, and vice versa 4 Ambient wind speed growing Expect need to decrease angle of wind deflector located on the side of heat exchanger farther from the wind side, and vice versa 5 Static pressure at pressure Decrease angle of wind sensors 318 decreases deflector closer to the pressure sensor sensed decrease of static pressure

(23) The control function performed by controller 230 may be rule-based, relying on a series of logical and/or continuous connections between parameters as presented, for example, in the table above. The control operation of the actual angle of deflection of wind deflectors 208 may utilize control tools and facilities known in the art, such as a proportional-integral-derivative (PID) control loop to provide a fast responding and stabilized control loop. In other embodiments, the control operation may be simpler (and thus cheaper) and utilize bang-bang control loop (control system that changes its working point between two edge points and changes the working point based on the control feedback, stabilizing around duty cycle that satisfies the control equation).

(24) Advantageously, the control function of controller 230 can operate using artificial intelligence systems such as neural network logic systems or fuzzy-logic systems. In such a neural network logic system, certain parameters, e.g. those mentioned in the above-mentioned chart such as wind direction, temperature difference and static pressure, etc. can each be connected in a formulation by strength variable weights to build a data set on which the neural network learns and provides an optimal output for operating the system so that improved performance or predictability of the system by controller 230 be achieved. Similarly, when fuzzy-logic systems are used, different weighting is given to these parameters to provide a set of outputs of controller 230 so that improved performance or predictability of the system by controller 230 be achieved.

(25) Reference is made now to FIGS. 3A, 3B, 3C and 3D, showing heat exchangers 310, 320, 330 and 340, respectively in four different working conditions, as a function of the wind, according to embodiments of the present invention. FIG. 3A shows heat exchanger 310 in a situation where the wind velocity is zero. At this state, wind deflectors 316A, 326B are raised (angle is close to 180 degrees), acting as tip back-flow preventers. FIG. 3B shows heat exchanger 310 in a situation where the wind blows from right to left in the drawing. Thus, in such a situation, wind deflector 326A is lowered and wind deflector 326B is raised. FIG. 3C shows heat exchanger 310 in a situation where the wind blows from left to right. Accordingly, wind deflector 336A is raised and wind deflector 336B is lowered. FIG. 3D shows heat exchanger 310 in a situation where the wind blows from right to left at low speed. Accordingly, wind deflector 346A is lowered but to an actual angle bigger than that of FIG. 3B.

(26) In a further embodiment of the present invention shown in FIG. 3E, showing e.g. a cross-sectional view of heat exchanger 2 along line AA (see FIG. 1A) means for diverting wind such as louvers installed below the fans in heat exchanger 350 in order to induce the flow of the wind below the fans to flow in the direction of the axis of the fans. As can be seen from FIG. 3E, louvers 356A, 356B and 356C can advantageously be positioned below each fan 354 and each be provided with rudder 357A, 357B and 357C to ensure that the flow of air from the wind beneath the fans is induced to flow in the direction of the axis of the fans whatever the direction of the wind. Other alternative means, such as an external electrical/mechanical means or controller which is controlled by e.g. an aerodynamic wind direction apparatus, can be provided instead of a rudder If the direction of the wind is known to be almost always in one certain direction, then only the first fan and also the central fan can be installed with such louvers. As can be seen from FIG. 3E, the height of the each louver can be different from the other louvers. Usually, louver 356C closest to the inlet of wind (upstream) to heat exchanger 350 will advantageously be positioned higher than the other louvers, so that louver 356B will be positioned higher than louver 356A. In this embodiment, louvers of different sizes can be used, see FIG. 3F showing small multiple louvers 360 and FIG. 3G showing large multiple (less than in FIG. 3F) louvers. Furthermore, the height of the louver frames from the ground can be fixed or adjusted according to wind velocity and/or feedback from fan 354 air flow distribution (see e.g. FIG. 3H).

(27) In still further embodiment of the present invention shown in FIG. 3I, showing e.g. a cross-sectional view of heat exchanger 2 along line AA (see FIG. 1A) means for diverting wind such as deflector 362, installed on the ground advantageously positioned upstream heat exchanger 360, as far as the wind is concerned, is used to divert the flow of the wind towards the lower portion of the heat exchanger, i.e. beneath the air cooled condenser pipes or bundles and fans. This reduces or just about eliminates the stagnation region produced by the wind usually under the upstream side of the heat exchanger under the upstream fan and to some extent under the second fan. The deflection of the air flow brought about by the deflector is a function of the of the angle of the deflector from the ground level, horizontal distance from the bundle (air cooled condenser pipes) upfront corner, length of the deflector and optionally a free air path between the ground and beginning of the deflector (L in FIG. 3I). When no wind is present, angle usually is 0 degrees. In actual fact, the use of deflectors in various positions under the heat exchanger is also effective but it serves winds from one direction. Placing the deflector under the center of the middle fan has the potential to provide good flow results and is additionally advantageous as it equally improves air flow when winds approach from either direction. In a further option, rather than one such diverter, two diverters positioned on the ground can be provided, on opposite sides of the heat exchanger, i.e. one on the upstream side and the other on the downstream side, can also provide good flow results to also provide improved air flow from either wind direction. Furthermore, such deflectors can be used in conjunction with the heat exchanger wherein the deflector can be located in other directions relative the heat exchanger to provide good flow results when the wind flows from a different direction relative to the heat exchanger. Winds blowing along the length coordinate of the heat exchangers array will affect the upstream bay and influence only the upstream fans which may be two or three or even six of them while winds blowing perpendicular to the length of the heat exchanger array may influence half of the fans.

(28) Moreover, it should be pointed out that the present invention and its embodiments refers to a heat exchanger for cooling liquid and/or vapor, or fluid.

(29) Additionally, advantageously, wind diverters, e.g. 208 can be made up of several segments so that wind pressure on the wind diverters is reduced. In such a manner, the positioning of the wind diverters can be more accurately controlled.

(30) In addition, it should be pointed out that the present invention and its embodiments can be used in heat exchanger having e.g. two or three rows of fans along it length.

(31) In a further embodiment of the present invention, advantageously, evaporative cooling wherein water is sprayed into the air flowing through the heat exchanger can be used to improve the cooling achieved by the heat exchanger of the present invention. By using the methods of the present invention, the possible dispersion of such water used for evaporative cooling by the present heat exchanger will be reduced or virtually eliminated.

(32) Reference is made now to FIG. 4, which is a flow diagram presenting a method of operation of a system, such as system 200 (FIG. 2), according to embodiments of the present invention. A system, such as system 200, for minimizing the undesired effect of wind blowing over a heat exchanger, such as heat exchanger 201, may be set to have its wind deflectors (such as wind deflectors 208) set to an uppermost position when power-up process commences (block 401). The initial angle of the wind deflectors may be set to an angle other than the uppermost angle, based on accumulated experience at the specific system location and other specific parameters. Once the system is operative, readings from its sensors (such as outlet temperature sensors 210, ambient temperature and wind sensor 212, inlet air pressure sensors 318, etc.) are collected, recorded and compared to previous readings (block 402). When a change in a received reading of a parameter is detected (block 403), the system will carry out a correction command, based, for example, on a set of rules saved in the system (block 404), and will repeat its cycle in block 402. If no change in any parameter, that causes a correction operation, was detected, the system returns to block 402 and repeats its cycle. It will be noted that loop parameters, such as cycle time, and system control parameters, such as hysteresis band (to refrain from undesired small corrections), may be set and used, as is known in the art.

(33) While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.