FI114821B - Method for controlling a supply air apparatus - Google Patents

Description

1 114821

A method for controlling the supply air system

TECHNICAL FIELD The present invention relates to a method for controlling the supply air equipment for e.g. air supply and temperature control in spaces on ships, which is connected to at least one ventilation duct and controlling the temperature to a desired temperature level, wherein the control unit is set to lower the temperature level from an initial value to a set value that differs by a certain amount from said initial value.

Background of the Invention

In ships, air is introduced into spaces such as cabins. The air is used to regulate the room temperature and to replace the air leaving the room via ventilation.

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Each condition so ventilated is normally equipped with a thermostat so that the setpoint can be obtained in some kind of control or air conditioning control system. If the setpoint is taken as the starting point, the choke device of the supply air system will automatically adjust, for example, to provide 25 higher cold air volumes. On cruise ships, it is common for cold air volume to be dimensioned into subsystems and components of the air conditioning system. This takes advantage of the coexistence factors so that the system does not become oversized.

»* 30 In this context, there is often the problem that, when arriving from a shorter or longer stay, the passenger is prepared to return to the cabin by setting the thermostat to the lowest possible temperature in the past. In this case, the cabin is comfortably cool after, for example, a warm day at the beach. Often, however, the 35 is too cool in this position.

Such an adjustment means a waste of energy during the time when the cabin is not occupied, and means that the vessel's cooling equipment is overloaded with 2 114821 units. Another problem is that cleaning staff, who try to keep themselves cool while cleaning the cabins, also adjust the thermostat to the lowest possible temperature and then forget to adjust the thermostat again.

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Various systems are known for supplying supply air and exchanging exhaust air. It is common to export 100% fresh air, dried and tempered, to a large number of supply air devices, which at the same time form diffusers for air distribution. The supplied air 10 may be post-heated from a low level or mixed with warmer air so as to obtain the desired room temperature. Such supply air devices are controlled to obtain the correct flow and temperature at the pressure on the supply side of the device, which in turn depends on how other supply air devices of the same supply air system are adjusted.

15 Adjustment is thus a recurring event that must be repeated several times to achieve the desired result. A faulty supply air device will then affect all other devices in the same system and cause inconvenience or constant readjustment. Increasing standards of pleasure in ship cabins have resulted in the current being close to the limit of 20 feedable air that can be carried into the cab from a single device without drawing. Increasing the number of supply air devices is an uneconomic solution.

TECHNICAL PROBLEM: The purpose of the present invention is to provide a supply air system of small size which produces a low self-pressure drop for efficient air supply but accurate throttling over a large flow range and produces little noise throughout said flow range.

T: 30

Solution This is achieved in accordance with the invention by adjusting the flow control means and the temperature control means to rapidly reduce the temperature within a predetermined time, and then: after this time has elapsed, re-adjusting to a temperature level lower than the original level at which the temperature was before it was calculated.

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3 114821 Through regular calibration, zero quality pressure transducers can be used during zero flow.

5 Providing the control unit with information about the position of the volume flow control elements - the set pressure - allows the flow changes to be adjusted more quickly and accurately.

DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the embodiment shown in the accompanying drawings. In the drawings, Figure 1 is a schematic perspective view of an air conditioning system having a supply air device for controlling the temperature of the invention, and Figure 2 is an enlarged view of a control unit for controlling the supply air device.

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Description of Embodiments

The embodiment of the air-conditioning system shown in Figure 1 comprises an inlet duct 10, an inlet air unit 11, a diffuser 12 and a control unit: arranged means (not shown) ·: · for controlling the volume of air flow to the diffuser 12 and means for reheating the supply air.

T: 30

Alternatively, hot and cold air can be supplied to the diffuser via a dual duct system, whereby air mixing and flow control are performed by a combination of supply air equipment and diffuser.

The control unit 13 is conventionally provided with a temperature sensor (not ·; ···) for detecting the temperature of the space in which the control unit is installed. The vent holes 14 in the hood surrounding the temperature sensor ensure that the sensor is in contact with the ambient temperature.

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To the front of the control unit 13 is a control panel comprising three control keys 15, 16 and 17. Of these keys, a key 15 is used to raise the temperature, a key 16 to lower it 5 and a key 17 is used to rapidly lower the room temperature. The 18 rows of LEDs are used to indicate temperature changes from the normal value.

When the key 17 is pressed, the maximum available amount of cold air 10 is quickly introduced into the space at a pre-programmed time, e.g., 10 minutes. The microprocessor in the control unit 13 then instructs the room temperature to be allowed to rise to the value it was in before the key was pressed, minus e.g.

1 ° C. This method of adjustment is based on the assumption that the person who pressed the button 17 felt that the room was too warm and did not want the temperature to return to the level that existed before the button was pressed. Further, for example, it is sufficient for the cleaning staff if the maximum coolness is maintained for about 10 minutes so that the space can be cleaned before the system 20 returns to "normal mode". When the key 17 is pressed, the stepper motor-controlled valve can be made to open, for example, twice as fast as normal adjustment to accelerate space cooling without the stepper motor and valve mechanism being consequently worn out or having to be oversized.

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Figure 1 illustrates the connection of the computer 19 to the control unit 13. The computer is used to control the supply air equipment with respect to the flow control range of the throttle members.

·· * 30 In order to use simple and inexpensive quality sensors whose signal output properties change with time as the pressure changes, automatic calibration is used periodically so that the pressure sensor provides acceptable accuracy between calibrations. This is done by generating a zero current to the air conditioning system, whereby the output signal is measured. Zero flow is achieved by stopping the fan using the system as a function of time. Calibration is performed each time a zero flow is achieved at a specified time interval. The resulting zero flow is considered to be expressed, - 1 1 4821

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each time the pressure sensor output signal drops below a predetermined level.

Because controlled level fluctuations in the duct system may be due to variable air intakes from other equipment connected to the system, pressure fluctuations in the fan inlet / outlet air, etc., the flow will vary if the volume control elements are stationary. The process of maintaining a given flow and of changing the flow takes place of the feedback of the normally obtained flow to the control unit.

10 This feedback can cause slowness and vibration problems throughout the control system, which in turn results in room temperature fluctuations and unnecessarily high energy consumption and volume flow control elements wear.

15 This is avoided by transmitting to the control unit 13 information about the position of the volume flow control elements - the prevailing pressure - the volume flow achieved, whereby position changes can be made more quickly and accurately.

The invention is not limited to the above exemplifying embodiments, but several modifications are possible within the scope of the following claims.

Claims (3)

A method of controlling an supply air apparatus (11) for ventilation and temperature control of the spaces, e.g. on vessels, the apparatus being connected to at least one supply air duct (10) and comprising means for volume control of the air flow to the space, means for temperature control of the air flow to the space, and a control unit (13) for controlling flow and temperature, for adaptation to the desired temperature level, wherein the controller (13) is employed for lowering the temperature level from an initial value to a set point located at a certain distance from said origin value, characterized in that the flow regulating means and the temperature regulating means are adjusted. for a rapid lowering of the temperature for a predetermined period of time, and after these time periods, these means are reset to achieve a temperature level lower than the original value that existed before the temperature decrease was started. 2. A method according to claim 1, characterized in that an accurate flow control is achieved by a periodically recurring zero calibration of a differential pressure gauge included in the controller (13), which calibration is performed by the controller itself detecting a zero flow. 3. A method according to claim 1, characterized in that the control unit (13) is provided with information on the throttle characteristics of the volume flow control means, which information is used for rapid and accurate temperature control of the space, and energy saving. f