FI104131B - Control of indoor air temperature and relative humidity in the unit - Google Patents

Description

104131

Field of the Invention

The invention relates generally to the control of indoor air properties of equipment rooms, in particular to the control of temperature and relative humidity in electrical or telecommunications equipment rooms which are located in a humid environment and require cooling equipment to ensure reliable operation.

BACKGROUND OF THE INVENTION Maintaining the relative humidity of indoor air in electrical and telecommunication facilities (hereinafter referred to as the more general term equipment), such as outdoor enclosures, is important to ensure normal operation of the equipment. Too high / low relative humidity in the indoor air shortens the life of the equipment and can also cause malfunctions.

15 Electrical equipment produces heat when it is operating. However, large quantities of heat cannot be removed from enclosed spaces without the use of mechanical work equipment such as air-to-air heat exchangers, air-to-liquid heat exchangers or so-called heat exchangers. heat-pipe heat exchangers (hereinafter all referred to as heat exchangers). With extreme variations in ambient temperature and / or humidity, such as those occurring in tropical conditions, equipment conditions, and the like. condensation / condensation of indoor air into water occurs in the heat exchanger. Condensation typically occurs when the ambient temperature drops • · •; (evening or night). This may endanger the operation of electrical equipment.

* · / ·· / In the past, moisture or condensation problems in electrical or telecommunications facilities have been addressed by, for example, compacting the enclosure to prevent water vapor from entering the enclosure. This is an expensive solution and its reliability over time is questionable. .

Another known solution used to eliminate the moisture problem is to install various chemical dehumidifiers in the device compartment. However, these chemical • • ·:. * · 30 dehumidifiers have a very limited lifetime and require · ·. · · Regeneration / refreshment very often depending on the conditions.

. ···. Various mechanical «* * devices have also been used to control humidity conditions, such as refrigeration devices, which create a device space at a particular point.

'; ; · 'The cold point where water vapor condenses into water which is diverted in a controlled manner.

A common disadvantage of the known solutions described above is that they are additional hardware cooling devices, which make the equipment more complex, require additional investment, increase the total energy consumption and / or increase the maintenance of the equipment.

5 Summary of the Invention

The object of the invention is to overcome the drawbacks described above and to provide a solution to the humidity problem which makes it possible to make the best use of the technology existing in the device space.

This object is achieved by the solution defined in the independent claims.

The idea of the invention is to control the relative humidity of the indoor air of the device space by means of the same cooling equipment used to handle the temperature control. This is typically done by reducing the relative humidity by increasing the indoor air temperature of the device space in response to the increase in relative humidity. This is done simply by reducing the cooling power applied to the device space by the cooling apparatus. The solution is based firstly on allowing the absolute humidity of the unit to monitor the value of the absolute humidity of the outdoor air and secondly on the fact that the same amount of water vapor causes higher relative humidity at lower temperatures than 20 (i.e. absolute humidity at least approx. Thus, the indoor humidity conditions of the device space are controlled by adjusting the indoor temperature in response to the relative humidity of the indoor air (or a quantity that indicates it) within a temperature range that is permissible for • · 25 devices in the device space.

Advantages of the solution according to the invention are its affordability (in economic terms) and its reliability. Affordability is based on the more efficient utilization of the existing equipment and the minimal amount of additional components required. From a service point of view, the solution 30 of the invention also becomes very advantageous. This is because the adjustment required ·· 'logic is typically quite reliable and maintenance free.

··· Due to the solution of the invention, the device space is no longer required to be vapor-tight, which in turn allows for significant economic savings.

An important additional advantage of the solution according to the invention is that the devices or components thereof placed in the device have a long life expectancy and a very high probability of improving their reliability. This is because temperature control due to relative humidity reduces the temperature variation that occurs in the device space as a function of time (e.g., the difference between the maximum and minimum temperatures occurring during the day is reduced).

List of figures

In the following, the invention and preferred embodiments thereof will be described in more detail with reference to the examples in the accompanying drawings, in which Figure 1 illustrates a device space with an adjusting mechanism according to the invention, and Figure 2 is a flow diagram illustrating Fig. 3 is a flow chart illustrating the control of the invention when using temperature measurement alone.

Detailed Description of the Invention. In the following, the invention will be explained in more detail with reference to an example, I * ': wherein, for example, the device space of a telecommunications or electronic device is provided with

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a known heat exchanger for treating said patient. equipment refrigeration ;; of Association.

: Normally, the relative humidity of the unit air rises to the condensation level (100% RH) when the outdoor temperature drops sufficiently. In this case, the unit's heat exchanger • »25 is too high for the conditions and the air in the unit space is too cool. According to the invention, the control of the relative humidity of the indoor air of the device space is based on reducing the heat transfer capacity of the heat exchanger in response to the increase in relative humidity. As the heat transfer capacity decreases, ': the temperature of the indoor air rises and its relative humidity decreases (because the same: the amount of T 30 water vapor causes a higher relative ···' humidity at lower temperatures than at higher temperatures). By adjusting the heat transfer capacity of the heat exchanger, it is therefore possible to achieve both sufficient cooling of the electronic equipment and acceptable relative humidity of the indoor air.

: .I. Figure 1 illustrates the principle of the invention by schematically illustrating a device cabinet 10 according to the invention equipped with a conventional heat exchanger 104131 4. The internal circulation of the heat exchanger is performed by a fan (or pump for fluid circulation) 14a and an external circulation by fan (or pump). Between the inner and outer circuits there is an actual transfer member 15 (honeycomb, plate pack, etc.), which stores heat and transfers it from the inner rotor 5 to the outer circulation.

Inside the device compartment is located a sensor 11 for measuring the indoor temperature of the device and possibly also a sensor 12 for measuring the relative humidity of the interior air of the device. The former is preferably arranged in the highest temperature location (near the top of the device or near the hottest devices). The latter, in turn, is advantageous to be located where the relative humidity is highest.

However, the relative humidity sensor 12 is not necessary and is therefore represented by a dashed line. This is because the relative humidity can only be controlled by a control message from the temperature sensor, knowing the geographic location of the device space. The location makes it possible to determine the absolute humidity which is not exceeded under any circumstances (except for spikes caused by rain; the device is protected against splashing water). For example, under tropical conditions, the typical maximum value for absolute humidity is 0.025 (kg H 2 O / kg k.i., i.e. kilograms of water vapor per kg of dry air I 4 1 20). This absolute humidity and the maximum permissible relative humidity correspond to a certain temperature value (which can be found, for example, in the wet and wet without Mollier diagram). This is enough to control relative humidity <I! : being that temperature control takes into account this temperature value so that the indoor air temperature is not allowed to fall below this value. Therefore,

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25 that the relative humidity of the device space is always within the permissible limits.

The absolute humidity of the indoor air of the unit is thus allowed to freely monitor the value of the outdoor air. In other words, the device space is not vapor tightly isolated from its surroundings. In this regard, it is sufficient that the entry of external water into the device space and the significant mixing of outdoor and indoor air (additional cooling) is prevented.

.L 'Temperature sensor 11 and humidity sensor 12 if the latter

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is used, the signal is coupled to the control logic circuit 16 to control the heat exchanger power. This can be accomplished, for example, by adjusting the ratio of airflow / mass flowrate (flow ratio · ... · 35 detta) or heat transfer surface area of the internal and external circulation of the conveyor. In practice, it is probably the simplest and most advantageous to control the airflow / mass flow ratio.

The adjustment of the air flows of the internal and external circulation of the heat exchanger can be effected, for example, by adjusting the rotational speed of the external heat exchanger fan 14a. Thus, the indoor air circulation in the device space continues to operate at a constant speed, providing the airflow conditions required for cooling the electronics.

As the temperature in the device space drops and the relative humidity of the indoor air rises to a certain predetermined value (e.g., 60% RH), the control logic 16 reduces the cooling power of the devices by reducing the speed of the external heat exchanger fan 14b. Information on the change in relative humidity is obtained either directly from the relative humidity value from sensor 12, if used, or from the temperature sensor 11 alone, whose signal indicates that the temperature has dropped to a value that corresponds to a predetermined relative humidity value value is a certain constant).

15 The RPM is reduced until the relative humidity of the room reaches the desired value (or the indoor temperature of the appliance reaches its maximum value).

Fig. 2 is a flowchart illustrating control logic. , the control performed by the circuit using both temperature and relative humidity measurement.

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Initially, the upper limits of the allowable range are set for temperature (Tmax) and relative <;; its relative humidity (pmax) and the lower limit of relative humidity (pmin), step 20.

i «After this, we switch to continuous mode operation, which starts with control \ i. the logic circuit reads the unit indoor temperature T from sensor 11 (step 21) and «* 25 compares the read value to the maximum allowed value (step 22). If the temperature is found to be greater than the maximum allowable value, the cooling power is increased to reduce the temperature to the allowable range (step 23). When the temperature is less than or equal to the maximum allowable value, read 'from the transducer 12: the relative humidity value p (step 24) and compare the value read to the maximum allowable value (step 25). If the value read is greater than the maximum allowable value, the cooling capacity to be applied to the space is reduced (step 27).

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If the read value is found to be less (or equal) than the maximum allowable value, the next step is to test whether the read value is less than the minimum allowable value (step 26). If this is the case, the cooling capacity of the space is increased, but if this is not the case, return to the beginning to read the new temperature value.

104131 6

Fig. 3 is a flowchart illustrating the control logic control when using temperature measurement alone.

For adjustment, the maximum relative humidity and the maximum allowable temperature that can be allowed in the unit are first determined. The minimum indoor air temperature in the enclosure is then determined from the installation site air-5to conditions (minimum and maximum absolute humidity, minimum temperature! And maximum), eg using the Mollier diagram. Thus, the upper and lower limits of the allowable range for temperature (Tmax and Tmin) can be set, step 30. The lower limit of temperature is thus dependent on how high relative humidity is allowed. After this, the continuous mode operation is started, which begins with the control logic circuit reading the temperature T in the device space from the sensor 11 (step 31). The value read is compared to the set upper limit (step 32). If the ambient temperature is greater than the maximum allowable value, the cooling capacity of the space is increased (step 33). If this is not the case, the next step is to determine whether the prevailing thermal state is less than the minimum allowable value (step 34). If this is the case, the cooling power is reduced (step 31). Otherwise, continue reading the new value for the ambient temperature. In the manner described above, the temperature is "continuously maintained within the permissible range.

:. · Ί Apparatus with a temperature sensor and a control algorithm 20 as shown in Figure 3 is, of course, a more economical alternative than equipment with both a temperature sensor and a humidity sensor. However, in spite of the stricter regulation, it can often be a sufficient alternative. The equipment with both a temperature sensor and a humidity sensor, in turn, provides more precise control and, as a result, e.g.

25 increased reliability. If a fine adjustment is required, a humidity sensor must also be used.

There are many different ways of implementing the principle of the invention. options, which are briefly described below.

"· For example, reducing / increasing the cooling power can be accomplished in a number of different ways. Because these techniques are known per se and do not relate to the actual: ·: Inventive idea, they will not be described in detail herein.

The external fan control can be carried out, for example, in two or:: V multiple power stages. For example, using two speeds may be: '1': practically a sufficient alternative.

35 Adjustment of air or mass flow rates can be achieved by influencing | 7 104131 either or both of the streams. Adjustment can also be effected, for example, by restricting air flows with control dampers or by influencing the amount of flow to the suction nozzle (honeycomb, plate pack, etc.) by ducts.

The idea of the invention can also be utilized in the cooling of compressor 5. In this case, the adjustment can be effected, for example, by limiting the amount of air in the device space which passes through the evaporator, thereby reducing the cooling capacity of the device space.

Humidity and temperature measurement can also be implemented in many different ways. Humidity can be measured, for example, based on temperature, optically, electrically, differential pressure, weighing (the weight of the material varies with moisture conditions) or physical changes in the material. The temperature may be measured, for example, based on the thermal expansion of the liquid, on the basis of the thermal expansion of the solid, on the basis of the capillary effect, on the basis of the thermal electric phenomenon, on the basis of the electrical resistance of the material. Since the implementation of the measurements is not related to the actual invention, they are not described in further detail. What is essential for the measurements is that they can be carried out in a manner known per se and that known and commercially available sensors can be selected for the measurements. Some commercially available sensors are Vaisala HMP 35D Y 20 (for relative humidity measurement) and Vaisala DTS12A (for temperature measurement).

i 'γ Although the typical use described above, where the temperature is raised when the relative humidity rises above the allowable limit, it cannot be ruled out: Y: the possibility of using the same idea in the opposite direction (ie 25 lowering the temperature if the relative humidity decreases) and it makes sense for the devices to be placed in the device space. In principle, the idea of the invention can also be used anywhere. . ·. equipment, etc. in a room with indoor air requirements similar to • t ·. ·· Electric or Telecommunication Space for Indoor Air, so the term Device Space is understood • · 30 in this sense, a term that is not necessarily limited to electrical or telecommunications equipment space.

Although the invention has been described above with reference to the examples of the accompanying drawings, it is to be understood that the invention is not limited thereto but can be modified in many ways within the scope of the 35 inventive ideas set forth in the appended claims.

Claims (6)

104131 1. A method for controlling the indoor air temperature and relative humidity of a device compartment (10), which method comprises adjusting the indoor air temperature of a 5 device compartment by modifying its devices! cooling capacity of the cooling unit (13) belonging to the unit so that the indoor air temperature remains within the temperature range allowed by the room space requirements set by the units in the unit, and - the relative indoor humidity of the unit is controlled by the same cooling unit; Whereas the actual humidity is within the permissible value range with respect to the air humidity requirements set by the equipment in the equipment room; characterized in that: - based on the absolute humidity at the geographic location of the device space and the temperature and humidity requirements set by the devices, the lowest and highest allowable values for the indoor air temperature of the device space are selected; and the highest allowed value. :. 20 Method according to claim 1, characterized in that: V. that the device space (10) is provided with a heat exchanger and the adjustment is made by decreasing the heat transfer capacity of the heat exchanger in response to an elevated relative: to the temperature indicating humidity. A method according to claim 2, characterized in that the heat transfer capacity of the heat exchanger is reduced by changing the ratio of the flow rates of its internal and external rotations. Method according to Claim 3, characterized in that the heat transfer capacity of the heat exchanger is reduced only by reducing the flow rate of its external circulation. A device cabinet (10) comprising: - a cooling device (13) for controlling the indoor air temperature of the cabinet, · · · - first means for measuring the relative humidity of the indoor air: - an indicating quantity, and - second means (15,16) for adjusting the indoor air. relative humidity · / · .; By varying the indoor air temperature in response to said quantity indicating 104131 relative humidity having reached a certain threshold, characterized in that the first members comprise a temperature measuring sensor (11) only, and that the second members also have information stored at a temperature corresponding to said limit. value. A device cabinet according to claim 5, wherein the cooling means comprises a heat exchanger, characterized in that the second elements comprise a fan (14b) for maintaining the external rotation of the heat exchanger and a control logic circuit (16) for controlling its speed. • 1 I · I «1 V« 1 · • • • • • • M • I I • • f «• I • • • • 104131