WO1997009571A1

WO1997009571A1 - A method and arrangement for adjusting an air-conditioning system

Info

Publication number: WO1997009571A1
Application number: PCT/FI1996/000472
Authority: WO
Inventors: Raimo Nyberg
Original assignee: Fläkt Service Oy
Priority date: 1995-09-08
Filing date: 1996-09-04
Publication date: 1997-03-13
Also published as: EP0848798A1; AU6877496A; ATE215208T1; DE69620201T2; FI100357B; DK0848798T3; FI954221A0; DE69620201D1; FI954221A; EP0848798B1

Abstract

The invention relates to a method and arrangement for adjusting an air-conditioning system by means of relative adjustment, in which the supply/exhaust air valves (1 - 5) of the system are adjusted starting from a valve (1) located the remotest in a branch duct (6), a so-called reference valve, so that the air flow rate of the reference valve is measured and the ratio of the air flow rate of the reference valve and the designed air flow rate is calculated and the other valves (2 - 5) of the branch duct (6) are adjusted in order starting from the reference valve so that each valve has the same ratio of the measured and calculated air flow rate and the designed air flow rate as the reference valve. For simplifying the measurement, after the measurement of the reference valve, the measuring duct of the following valve is connected parallel with the measurement of the reference valve, the ratios of the measured air flows and the designed air flows are generated, the ratio of the following valve is compared with that of the reference valve, and the adjustment of said following valve is carried out by comparing the above-mentioned values that may be observed parallel.

Description

A method and arrangement for adjusting an air- conditioning system

The invention relates to a method for adjusting an air-conditioning system by means of relative adjustment in which the supply/exhaust air valves of the system are adjusted starting from the valve located the remotest in a branch duct, i.e. a so- called reference valve, so that the air flow rate of the reference valve is measured and the ratio of the measured air flow rate and the designed air flow rate is calculated and the other valves of the branch duct are measured and adjusted in order starting from the reference valve so that each valve has the same ratio of the measured and calculated air flow rate and the designed air flow rate as the reference valve. The invention further relates to an arrangement for adjusting the air-conditioning system.

An air-conditioning system generally refers to a mechanical concentrated air treatment system in which air is pretreated before it is blown into a room and removed from the room by means of ductwork and supply/exhaust air devices. Room-specific air flows are always determined in air-conditioning plans on the basis of operations taking place in the room or the loads caused on the room, such as heat, moist, impurities etc. The operations taking place in the space are always taken into account when designing an air-conditioning system, and room-specific as well as supply/exhaust air device-specific measurement and adjustment are therefore important procedures before the start-up of the system. It must be noted that the ideal conditions in the room are only achieved by means of correct supply and exhaust air flow rates. In conventional relative adjustment, the adjustment is started from the valve situated the remotest in the branch duct, said valve also being a so-called reference valve. There are various types of air valves, the type of the reference valve may be e.g. PMD-12 and they may be e.g. two in number. The designed air flow rate may be e.g. 300 m³/h, which is 150 m³/valve. The valve manufacturer has made measurement and adjustment instructions for each valve type, providing specific values. Differential pressure measurement, for instance, may be used as a measurement method, in which case e.g. a micromanometer may be used as the measurement device.

Prior to the measurement it is ensured that the adjustment device is in the extreme open position. The micromanometer is connected to a measuring duct of the reference valve mentioned above, which provides as a result a certain differential pressure reading, such as 10 Pa. The air flow is thus obtained from the formula: q = k x- pi (1/s) .

The co-efficient k is obtained from a table provided by the valve manufacturer. The co-efficient k may be e.g. 13.4. The obtained air flow rate is 151 m³/h with the co-efficient 3.6, as the formula is 1/s. The ratio of the measured air flow rate and the designed air flow rate is thus 151/150 x 100 = 100 %.

It is important in relative adjustment that the measurement is carried out following the order related to the ductwork of the valves. The following step in conventional adjustment is to proceed to the valves in the following room. These valve units may be e.g. of the type PMT-12, and they may be three in number. The designed air flow rate may be 450 m³/h, that is, 150 mVvalve. The values related to the valve type are obtained from tables provided by the manufacturer. The micromanometer is connected to the measuring duct of the valve to be measured, and a certain differential pressure reading, e.g. 10 Pa, is obtained. The air flow rate resulted on the basis of the above formula is 108 m³/h and the ratio is 108/150 x 100 = 72 %.

The ratios obtained from the reference valve and the valve that was measured thereafter are unequal, and it is thus checked next that the damper of the latter valve is fully open. It is therefore necessary to throttle the reference valve in order that the same ratio would be obtained from both valves.

It is determined that, when the above valves have the same ratio, the ratio could be e.g. 80 %. It is calculated 150 x 0.8 = 120 m³/h, and the required differential pressure is calculated from the above formula pi = (q/k)², that is, 6.2 Pa. The reference valve is throttled to the value 6.2 Pa. Thereafter, the differential pressure of said second valve is measured and the value 12 Pa is obtained. On the basis of the measurement, the air flow rate of the valve is calculated according to the formula. The obtained air flow rate is 33 1/s x 3.6 = 119 m³/h. Thereafter, the ratio of the valve in question is calculated, and 79 % is obtained as the result. It is observed that the valves have the same ratio, that is, approximately 80 . O •

The adjustment described above succeeded without difficulty. In case the ratio had been different from the estimate, it would have caused more measurements and calculations.

The following step is adjusting the following valve in the branch, carried out in the same way as described above. It must be noted that a valve that is located between the valve to be adjusted and the reference valve and that has already been adjusted once must not be re-adjusted.

The conventional prior art method has the drawback of being slow, because, when the adjustment is carried out, it is necessary to move back and forth between valves located in separate rooms. It must be noted that in practice this method often requires a large number of measurements and calculations for each valve before an optimal adjustment is achieved. The above refers to the fact that in carrying out relative adjustment, the measurement result of the valve under adjustment must be compared with the value of the reference valve by calculating the air flow rate and the air flow ratio. Thereafter, provided that the ratio obtained from both valves is the same, the adjustment is completed as far as the valve in question is concerned. In case the ratios are not equal, the valve must be re-adjusted, and a new measurement and a new calculation must be carried out. This procedure is repeated until the same ratio is obtained from both valves. For the above reasons, the accuracy of the adjustment is not always optimal, and due to the difficulty of the adjustment it is not always carried out properly. This results in increased consumption of energy and e.g. deterioration of the air quality in the working environment.

The object of the present invention is to provide a method and an arrangement which avoid the drawbacks of the prior art. This is achieved by means of the invention. The method according to the invention is characterized in that after the measurement of the reference valve, the measuring duct of the following valve is connected parallel with the measurement of the reference valve, the ratios of the measured air flows and the designed air flows are generated, the ratio of the following valve is compared with that of the reference valve, and the adjustment of said following valve is carried out by comparing the above-mentioned values that may be observed parallel. The arrangement of the invention, in turn, is characterized by comprising first measurement means for measuring the air flow rate of the reference valve and second measurement means for measuring the air flow rate of the following valve, and a unit to which said measurement values are arranged to be supplied simultaneously and parallel and which is arranged to generate the ratios of the measured air flow rates and the designed air flow rates and which comprises means that are arranged to indicate when the values of the reference valve and the following valve are substantially equal.

The major advantage of the invention is the fact that it speeds up the measurement and adjustment, which improves the measuring accuracy substantially as compared with the prior art. Another advantage is the fact that one measurement device only is used in the invention. The invention allows optimizing the operational economy of the air-conditioning device with respect to the capacity used. Yet another advantage is compatibility e.g. to a portable personal computer, thus enabling fast and accurate documentation. The invention further allows co-operation between valve manufacturers, instrument manufacturers and service providers in product development.

In the following, the invention will be disclosed in greater detail with reference to a preferred embodiment shown in the attached drawing, the figure of the drawing illustrating a plane drawing of the air-conditioning system of an office building.

The adjustment of the air-conditioning system is carried out in accordance with the invention as follows. The supply air valves are indicated in the figure with reference numerals 1 - 5. The adjustment is started from the remotest valve 1, i.e. the so-called reference valve in a branch duct 6. This valve is located in office room 115.

The valve is of the type PMD-12 manufactured by Stifab Oy. The designed air flow rate to room 115 is 300 m³/h, in other words, the designed air flow rate of the air passing through valve 1 is 150 m³/h, as there are a total of two supply air valves in room 115.

In the method according to the invention, a unit 7 is used, to which unit the designed air flow of valve 1 is supplied to a sensor X. The co-efficient k = 13.4 of the valve type in question is obtained from the measurement and adjustment instructions provided by the manufacturer of valve 1, said co-efficient also being supplied to unit 7. The above data may be supplied to the unit individually or retrieved from a register of unit 7, said data having been stored previously in said register.

The measurement method to be used in differential pressure measurement. In that case, it is ensured prior to the measurement that the adjustment device is fully open. Sensor X of unit 7 is connected to the measuring duct of valve 1. Unit 7 is arranged to perform all the necessary calculations, and it thus immediately displays values 151 mVh for the air flow rate and 100 % for the ratio. The above data may be expressed e.g. by means of a display unit 8. In the following step, it is proceeded to room

114, in which a supply air valve 2 and two other similar valves are located, only one of which is marked in the Figure with the reference numeral 5. The designed air flow rate to room 114 is 450 m³/h, that is, 150 m³/h per each valve, valve 2 included. Said value 150 m³/h of the designed air flow rate is supplied to unit 7 to sensor Y. The supply air valve may be e.g. of the type PMT-12 manufactured by Stifab Oy, and the co¬ efficient k = 9.5 is obtained from the valve manufacturer's instructions. Said data may be supplied to unit 7 individually or it may be retrieved from the register of unit 7, as stated above. The unit is arranged to perform all the necessary calculations e.g. on the basis of the formula shown above. Sensor Y of the unit, which sensor is parallel to sensor X, is connected to the measuring duct of supply air valve 2, whereby uni^~ 7 immediately displays the air flow rate 108 m³/h and the ratio 72 % for sensor Y. The above values may be expressed e.g. by means of a display unit.

The ratios obtained for valves 1 and 2 are not equal, since the ratio of valve 1 is 100 % and the corresponding ratio of valve 2 is 72 %. It must be noted that sensor X is at this stage still connected to the measuring duct of valve 1. In this step it is checked that the damper of valve 2 is fully open. In case the damper is fully open, valve 1 must be throttled in order to obtain equal ratios for valves 1 and 2. The damper of valve 1 is throttled until the ratio of valve 2 is equal to that of valve 1. The procedure is easy to carry out since the ratios are displayed parallel on display units 8 and 9 of sensors X and Y of unit 7. The adjustment is completed when the same ratio, e.g. 8 %, appears on both displays. In the following step, it is returned to room

115, to supply air valve 3. As valve 3 is similar to valve 1, the initial data is the same as that related to valve 1. The designed air flow rate is 150 m³/h and the co-efficient k = 13.4, and the values are supplied to unit 7 cr retrieved from the register of unit 7 and supplied to sensor Y. Sensor X is still connected to the measuring duct of valve 1. In this step sensor Y is connected to the measuring duct of valve 3, whereby sensor Y of unit 7 immediately displays the ratio 111 % and sensor X displays the ratio 80 %. In this case, valve 3 must be throttled until the ratios of valves 1 and 3 are equal. Once the adjustment is completed, the value for the ratio displayed by the display units of sensors X and Y is 85 %. In the following step, it is proceeded to room

116, in which a supply air valve 4 is located. This valve is of the type PMD-12. The designed air flow rate is 120 m³/h and the co-efficient k is the same as that of valve 3. Said designed air flow rate is supplied to sensor Y while the other data is the same as that related to the previous valve. Sensor Y of unit 7 is connected to the measuring duct of valve 4, whereby unit 7 immediately displays the ratio 156 %, whereas the ratio of the reference valve simultaneously displayed on the display of sensor X is 85 %. Valve 4 must be throttled until the ratios of valves 1 and 4 are equal. Once the above procedure has been carried out, the ratio provided by sensors X and Y is 90 %, which indicates that the adjustment is completed. The following valves of the air-conditioning system are adjusted in the same way by comparing the result with the value of the reference valve each time. Once the adjustment is completed, the ratio of the total air flow may be above or below 100 %. The final adjustment of the air flows is thus carried out by means of the air-conditioning apparatus. In the case of the example, the supply air flow was adjusted by changing the position of the damper, but there are such types available in which the position of the valve is adjusted. In adjusting the exhaust air flow, the same principles are applied depending on the type of the valve.

Unit 7 may be implemented in a variety of ways. The quantities to be measured may be collected to the memory of the unit on the basis of pre-programmed initial data. The desired values may be read from the display of the unit directly digitally or analogically and/or the unit may indicate achieving a desired value with a sound or light signal, a graphic display, a combination of the above etc. The unit may also collect the obtained data in a memory, which data is directly transferable to a printer unit 10 or/and to the memory of the personal computer 11, for instance. The unit may be a battery or mains driven unit, and data may be programmed to it directly e.g. by means of the unit's own keyboard, , or data may be transferred to it from a personal computer, for instance.

The embodiment disclosed above is not intended to limit the invention in any way, but the invention may be modified completely freely within the scope of the claims. It is thus obvious that the arrangement of the invention or its details do not necessarily have to be exactly similar to those shown in the figure, but other kinds of solutions are possible. It is obvious, for instance, that the number of the sensors to be used may be chosen according to the need. The sensors measure the quantities used in the ventilation technology. The sensors may be battery or mains driven. Communication between the sensors and the unit may be carried out either by means of wires or as a wireless connection.

Claims

Claims :

1. A method for adjusting an air-conditioning system by means of relative adjustment in which the supply/exhaust air valves (1 - 5) of the system are adjusted starting from the valve (1) located the remotest in a branch duct (6), i.e. a so-called reference valve, so that the air flow rate of the reference valve is measured and the ratio of the measured air flow rate and the designed air flow rate is calculated and the other valves (2 - 5) of the branch duct (6) are measured and adjusted in order starting from the reference valve so that each valve has the same ratio of the measured and calculated air flow rate and the designed air flow rate as the reference valve, c h a r a c t e r i z e d in that after the measurement of the reference valve, the measuring duct of the following valve (2) is connected parallel with the measurement of the reference valve, the ratios of the measured air flows and the designed air flows are generated, the ratio of the following valve (2) is compared with that of the reference valve, and the adjustment of said following valve (2) is carried out by comparing the above- mentioned values that may be observed parallel.

2. An arrangement for adjusting an air- conditioning system by means of relative adjustment by adjusting the supply/exhaust air valves (1 - 5) starting from the valve (1) located the remotest in the branch duct (6), i.e. the so-called reference valve, for determining the ratio of the measured air flow rate and the designed air flow rate for the adjustment, c h a r a c t e r i z e d by comprising first measurement means (X) for measuring the air flow rate of the reference valve and second measurement means (Y) for measuring the air flow rate of the following valve (2), and a unit (7) to which said measurement values are arranged to be supplied simultaneously and parallel and which (7) is arranged to generate the ratios of the measured air flow rates and the designed air flow rates and which comprises indicator means (8, 9) that are arranged to indicate when the values of the reference valve and the following valve are substantially equal.

3. An arrangement as claimed in claim 2, c h a r a c t e r i z e d in that the indicator means (8, 9) comprise parallel display units.

4. An arrangement as claimed in claim 2 or 3, c h a r a c t e r i z e d in that the indicator means (8, 9) comprise a sound source, a light source or the like.

5. An arrangement as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the unit (7) can be connected to a computer (11) or a printer unit (10) .