Method and device for cooling circulating air

<td>REPUBLIC POLAND</td><td>(12) PATENT DESCRIPTION (19) PL (21) Application number: 375918</td><td>(11) 201381 (13) B1</td>

<td></td><td>(22) Date of notification: 25/11/2003</td><td>(51) Int.Cl. F24F 12/00 (2006.01)</td>

<td></td><td>(86) Date and number of the international application: 2003-11-25, PCT / EP03 / 13243</td><td>F24F 5/00 (2006.01)</td>

<td>patent Office</td><td>(87) Date and publication number of the international application:</td><td></td>

<td>Polish Republic</td><td>2004-06-10, WO04 / 048859 PCT Gazette No. 24/04</td><td></td>

(54)

A method and a device for cooling the circulating air

<td>(30) Priority: 27.11.2002, DE, 10255530.3</td><td>(73) The right holder of the patent: HOVALWERK AG, Vaduz, LI</td>

<td>(43) Application was announced: 12.12.2005 BUP 25/05</td><td>(72) Inventor (s): Edgar Beck, Balzers, LI Christoph Steinhausler, Gschwandt, AT</td>

<td>(45) The grant of the patent was announced: April 30, 2009 WUP 04/09</td><td>(74) Representative: Wojcieszko Jerzy, PATENT-PARTNER Patent Office</td>

(57) 1. A method for cooling the circulating air in a heat exchange process with adiabatically cooled process air, characterized in that the cooled process air receives heat from uncooled process air after its heat exchange with the circulating air.

11. Recirculating air cooling device with a first heat exchange device allowing it to be fed with circulating air and process air with a humidifying device for introducing water into the process air, characterized by that it has a second heat exchange device (12) for exchanging heat between the uncooled process air (6) before it enters the first heat exchange device (1) and cooled process air (6) after it exits the first heat exchange device (1).

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PL 201 381 B1

Description of the invention

The invention relates to a method and an apparatus for cooling circulating air in a heat exchange operation with adiabatically cooled process air.

The invention relates to the area of ​​so-called indirect adiabatic cooling, since the water required for adiabatic cooling is not introduced into the circulating air, but into the process air, which is preferably outside air. The adiabatically cooled process air enters as an enthalpy vent into the heat exchange operation with the circulating air and lowers its temperature.

The cooling capacity of such systems depends on the inlet temperature and the humidity of the process air. If, for example, this temperature is relatively high, then the cooling capacity is not sufficient to efficiently cool the circulating air. For this reason, it has hitherto been necessary to provide an additional compression or absorption cooling device.

Cooling installations of this type increase the cost of technical equipment. They consume high-grade energy in the form of electricity or fossil fuels, and also work with environmentally harmful cooling agents. Legal provisions are often required that restrict the use of high-grade energy and the use of environmentally polluting materials.

The object of the invention is to increase the efficiency of the indirect adiabatic cooling of the circulating air by simple measures.

For this purpose, the method initially named according to the invention is characterized in that the cooled process air takes heat from the uncooled process air after heat exchange with the circulating air.

After the heat has been exchanged with the recirculating air, the cooled process air has a temperature which is lower than the temperature of the uncooled process air. It can therefore absorb heat from the uncooled process air so that its temperature is lowered. The adiabatic cooling thus has an effect on the process air, the temperature of which has already been lowered. This has an advantage in cooling the circulating air, with the result that - in applications where the sensitized cooling of the circulating air is sufficient - additional compression or absorption cooling devices can be dispensed with. The technical and equipment expenditure required for this purpose is small. In addition to investment costs, operating costs are also falling as less energy and water are used.

It should also be emphasized that a permit is not required for the operation of the cooling device. Maintenance is simplified as there is no need for specialist refrigeration equipment. Any environmental burden that could be associated with the use of cooling agents is also eliminated.

Adiabatic cooling of the process air can occur before the process air enters the heat exchange operation with the recycle air. You can then speak of a two-stage diffusion evaporation. Single-stage diffusion evaporation may be more advantageous, in which adiabatic cooling of the process air occurs during heat exchange with recycle air. In contrast to the two-stage diffusion evaporation, the surface is wetted in this case by heat exchange with the injected water.

Depending on the operating status, the water temperature may fluctuate during one-stage adiabatic cooling. It has surprisingly been discovered that this causes significant influences on the operation of the method. If the water temperature is lowered, it is advantageous to conduct the circulating air and the process air in the heat exchange operation in a system of concurrent streams. Otherwise, a counter-current flow pattern is more preferred. In a further development of the inventive solutions, it is therefore proposed to lead the circulating air and the process air in their heat exchange operation in either a concurrent, counter-rotating or cross-flow pattern, or in a concurrent or counter-rotating cross-flow pattern.

The cooling capacity is adjustable, preferably by varying the mass flow ratios of the circulating air / process air and / or by varying the amount of water introduced into the process air.

PL 201 381 B1

The cooled process air is preferably sucked off after it has absorbed heat from the uncooled process air.

The device for solving the task posed has a first heat exchange device which enables the supply of circulating air and process air, as well as a humidifying device for introducing water into the process air, and according to the invention is characterized by a second heat exchange device, for exchanging the medium between the uncooled process air before it enters the first heat exchange device and cooled process air after it exits the first heat exchange device. The process air thus passes first through the second heat exchange device, then through the first heat exchange device, and thereafter it is discharged through the second heat exchange device.

In the second heat exchange device, the cooled process air absorbs heat from the uncooled process air and thus lowers its temperature.

It is preferable that the second heat exchange device, at least on the inlet side of the uncooled process air, can be bypassed via a bypass, namely in the case where the temperature of the uncooled process air makes its preliminary cooling in the second heat exchange device redundant. From this point of view, it is also advantageous to detach the humidifying device. Ultimately, it is possible to work with so-called free cooling, which uses the outside air to cool the room directly.

The humidifying device may be in the form of a scrubber, contact humidifier, high pressure humidifier or the like. It may be located between the first and second heat transfer devices. This arrangement can, as mentioned, be referred to as two-stage diffusion evaporation. More advantageous in some circumstances is a single-stage diffusion evaporation in which the moistening device is integrated into the first heat exchange device. Water is directly injected into the first heat exchange device and the heat exchange surface thereof is moistened.

It is advantageous in this case to operate the first heat exchange device in an arrangement of countercurrent, concurrent or cross flows depending on whether the temperature of the water is increased or decreased in the adiabatic cooling process.

In a significant further development of the invention, it is proposed that the first heat exchanger has at least two cross-flow heat exchangers, also these preferably capable of being operated in a cross-flow, counter-rotating or concurrent flow pattern.

Preferably, the process air is drawn in by a blower which is arranged in the path of the cooled process air downstream of the second heat exchange device. The blower thus draws in the process air through the device. This arrangement is made in such a way that the heating of the process air inevitably produced by the blower does not adversely affect the cooling capacity.

The invention is explained in more detail below on the basis of a preferred embodiment in conjunction with the attached drawing. The drawing shows in: fig. 1 a device according to the invention in a schematic representation; Fig. 2 - changes in the state of the circulating and process air in the diagram h, x.

According to FIG. 1, a first heat exchange device is provided which has two cross-flow heat exchangers 2 and 3. The first heat exchange device 1 is fed with circulating air 4, namely this air flows first through the cross-flow heat exchanger 2 and then thereafter. through the cross flow heat exchanger 3. The blower 5 ensures the transport of the circulating air 4.

The first heat exchange device 1 is further supplied with process air 6, which in this case is outside air. Also process air 6, which in this case is outside air. The process air 6 also flows first through the cross flow heat exchanger 2 and then through the cross flow heat exchanger 3.

The first heat exchange device 1 thus works in a concurrent cross-flow system, which is why it is advantageous that such an operating state of the device leads to cooling of the water injected into the first heat exchange device 1.

PL 201 381 B1

The first heat exchange device is for this purpose equipped with a humidification device 7 which injects water into the process air 6 and thus causes it to be adiabatically cooled. The water is collected in the well 8 and by means of the pump 9 it is led to the humidification device 7. The well 8 is provided with a water inlet 10 and a water outlet 11.

Before entering the first heat exchange device 1 and after exiting therefrom, the process air 6 flows through the second heat exchange device 12, namely as a result of the action of a blower 13 which is arranged downstream of the second heat exchange device 12 with respect to the cooled process air. The heat generated by the blowers 13 must not detract from the cooling capacity. Since the temperature of the cooled process air 6 after exiting the first heat exchange device 1 is lower than the temperature of the process air 6 before entering the second heat exchange device 12, in the latter, heat can be exchanged between the two streams of process air 6, namely from with the result that the process air 6, already at the lowered temperature, is subjected to adiabatic cooling. A corresponding increase in the cooling capacity is the result.

Figure 2 shows in the graph h, x an example for the single-stage adiabatic cooling that is possible with the apparatus of Fig. 1, line a showing the temperature reduction of the circulating air 4 in the first heat exchange device 1. Line b represents the temperature reduction. which the process air 6 experiences in the second heat exchange device 12. Line c shows the temperature decrease of process air 6 due to adiabatic cooling in the first heat exchange device 1, and line d shows the temperature increase of process air 6 in the second heat exchange device 12.

Within the scope of the invention, there are of course also possible variants of embodiment. Thus, the transport direction of the blower 5 can be reversed. The first heat exchange device 1 then operates in a counterflow, cross-flow pattern. This mode of operation is selected when the water temperature does not decrease between the process air inlet and its outlet. Moreover, it is possible to process decoupling the humidifying device from the first heat exchange device and operation between the two heat exchange devices. However, the integration of the humidifying device into the first heat exchange device is particularly advantageous. The first heat exchange device may be designed as a single stage, and the second heat exchange device may have a multi-stage structure. Furthermore, it is possible to bypass the second heat exchange device with a by-belt, whereby the lines b and d drop off in the diagram of FIG. 2. If, moreover, which is also possible, the humidification device 7 is switched on, the line c also drops out. The cooling effect is then merely the result of a temperature difference between the circulating air and the process air. Ultimately, the first heat transfer device may still be decoupled. The process air will then be blown directly into the room to be cooled.