AU635046B2

AU635046B2 - Air conditioning control system

Info

Publication number: AU635046B2
Application number: AU59011/90A
Authority: AU
Inventors: David George Maccoll
Original assignee: Maccoll David G
Current assignee: Maccoll David G
Priority date: 1989-07-21
Filing date: 1990-07-16
Publication date: 1993-03-11
Anticipated expiration: 2010-07-16
Also published as: AU5901190A

Description

635046 ORIGINAL FORM REGULATION 13(1) COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 TRANSITIONAL APPLICATION COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED:- "AIR CONDITIONING CONTROL SYSTEM' This invention is described in the following statement:- -2- This invention relates to control systems for the air conditioning of high rise buildings and in particular for varying the flow and quality of air to different parts of the building in response to varying external building skin temperature which ultimately effects the internal conditions.

Traditionally the temperature and flow of delivered air in high rise buildings is controlled by monitoring the air which returns, usually via the return air shafts and fans, to a central plant room. In addition to internal heat load changes there are appreciable, sometimes sudden, changes to the building skin temperature. The conditions become hotter or colder in different parts of the building depending on the direction of change. However, these differential changes are masked or cancelled by the mixing of air from the different areas of the building during their return path to the conditioning plant. Accordingly, conventional control systems cannot compensate for the variations in particular areas of the building, whereas this control system anticipates the internal variations using external sensors.

Further, there is an inevitable time lag between change in external climatic conditions effecting the air in the relevant internal part of the building and change in any corrective action of controllers as derived from the variables, being monitored. There is also a further time lag then in varying the condition and volume of air to that region to compensate for the effect of the climatic change.

I II -3- It is therefore an object of the present invention to provide a control system which anticipates the effect of climatic changes on the internal conditions in different areas of a high rise building and acts to compensate for those changes by altering the flow of air to those areas to achie Te greater comfort. It is a further object to achieve savings in the energy consumption of the air conditioring plant by causing differential flows of air between hotter and colder areas in the building.

The control system of the present invention comprises sensors located on the external walls of a high rise building which detect changes in the skin temperature of the building and a co-ordinating micro processor which monitors these sensors and drives actuators which modulate valves or dampers located in the air conditioning plant to allow greater or lesser volume/ temperature to different areas of the building. The actuators are driven in response to the external sensors in order to compensate for differential changes in ambient temperatures due to external climatic changes. Further, the micro processor monitors the position of all relevant actuators and can control the speed of the applicable fan in response to the same. This close temperature monitoring of the building's aspects allows hourly, daily and seasonally favourable conditions to directly influence the plants operational output capacity thus energy usage.

-4- Following is a preferred embodiment of the invention with reference to the drawings for a Variable Air Volume System, in which:- Figure 1 shows the layout of the main air conditioning feed ducts in the mid level plantroom of a high rise building; Figure 2 shows the location of dampers in the air conditioning ducts of the building; Figure 3 is a schematic diagram of the control system; Figure 4 shows graphs for the calibration of the controller of the system; and Figure 5 shows the special sensors on the building skin.

In Figure 1, the two main conditioners S6 (shown in broken outline) and S3 feed respectively four risers located in wells 1, 2, 3 and 4 which duct air to the upper levels of the building and four droppers also located in wells 1, 2, 3 and 4 which duct air to the lower levels. Four temperature sensors are located on the external walls in the minimum of shade at N, E, S and W.

In Figure 2, butterfly dampers are located in risers 1, 2, 3, and 4 and droppers 3 and 4 at the point where they leave the plant room level and in droppers 1 and 2 at the points where they feed into the west and north sides of low rise j i 41 i ,w floors above the shadowline. The latter dampers allow individual control over the air leaving droppers 1 and 2 for some of these lower levels.

In Figure 3 it can be seen that the sensors are connected to a micro processor which monitors the building skin temperature and optimises the operation of the boiler, the chiller and modulation of the damper motors. Because the conditioners supply mainly warm air in winter conditions and cool air in summer conditions inversion of the micro processor's output is necessary for winter operation.

The controller is calibrated for winter and summer operation as indicated in the graphs of Figure 4. In winter the dampers are fully open at 10 0 C skin temperature and fully closed at 16'C, while in summer they are fully closed at 15C skin temperature and fully open at 24°C. All set points can be varied and calibrated as required.

In operation then the system works in the following way. When one side of the building becomes hotter than the other, for example the east side from the morning sun in summer, the micro processor will register the increase in the sensor reading of skin temperature on the east side and activate the actuator which opens the dampers in the air conditioning ducts in shaft 3 supplying a greater quantity of cool air to the east side of the building.

-6- Similarly when the winter sun warms the east side of the building the micro processor will activate the actuator which closes the damper in the ducts in well 3 supplying warm air to the east side. Conversely, when the afternoon sun warms the west side of the building, the controller will activate the actuator which opens or closes the dampers in the ducts in shaft 1. When all areas are satisfied the fan supplying the appropriate conditioned air can be shut down completely.

The micro processor will also respond to changes in climatic conditions such as clouds blocking the sunlight and wind and rain causing cooling of the building skin. Further, it will be seen that the system responds in anticipation of the effect of these changes on the internal air temperature, thus greatly reducing the response time.

The control system can just as easily be applied to Variable Refrigerant Volume Systems.

There are numerous refinements which can be applied to this control system.

Dampers can be located so as to effect conditions in more limited areas such as those located in droppers 1 and 2 of Figure 2 above.

The appropriate aspect slkin temperature sensor/s can also be used, via the micro processor to optimise the start up of the air conditioning plant, heating or cooling, rather than time clocks via P.I.D Control (rate of change).

I. iitq -7- Similarly more sensors can be located on the external walls of the building to provide a more differentiated monitoring of skin temperature in different parts 100 of the building. These refinements can allow a highly differentiated management of the environment within a high rise building subject to different external conditions such as shadowing and different internal requirements of air conditioning.

The working model example of the invention, and extensions of the principle, is 105 Town Hall House, 456 Kent Street, Sydney, Australia.

DATED this 16th day of November 1992.

DAVID G. MACCOLL 8 WINDSOR PLACE ST. IVES, N.S.W. 2075

AUSTRALIA

APP. NO. 59011/90

DAVID