TITLE

AIR CONDITIONING EQUIPMENT

DESCRIPTION

TECHNICAL FIELD

The present invention relates to a reduction of the electrical effect of fans in an air conditioning equipment having ingoing and off air when a varying part of the off air is brought over to the ingoing air to be recirculated to the ventilated space.

BACKGROUND OF THE INVENTION

There exist different conditions when a return air admixture to the ingoing air is wanted, such as e.g., in shopping centres where heat and cold are distributed by air. In these system there is normally required a larger amount of air to be able to carry the heating effect, and the cooling effect, respectively, which is motivated from a hygienic point of view. To increase the amount of outdoor air, alternatively, normally leads to an increased use of energy to condition the air to the right temperature.

There are different needs to regulate the return air admixture. One is to take care of the temperatures that exists indoor and outdoor and to control the mixture in such a way that least possible amount of energy is used to reach the desired temperature of the air introduced. Another is to continuously determine any form of hygienic factor, normally the amount of CO ₂ and to control the admixture so that the air is regarded as fresh, independent of the number of visitors in the building.

SE-454,461-B discloses a ventilation system with heat and a method to control the system. The system comprises heat exchanger with channels for outdoor air, off air and return air, ingoing air, ingoing air fan, off air fan, mixing chamber for mixing return air into ingoing air as well as a heating battery.

SE-523,832 discloses temperature compensation in a air conditioning apparatus and method for controlling the mass flow in an air conditioning apparatus. Compensation of the temperature is based on that air of different temperatures

have different densities and whereby one makes sure that a desired volume flow with the density, mass flow, in an air stream.

US-5,024,263 discloses a method and apparatus for controlling air flows and pressures at air conditioning. Thereby the apparatus comprises a heat exchanger, and off air fans, air filters, and heating and cooling elements.

This known technique is not disclosing an equipment having a simple control of a return airflow based on an ingoing air fan only.

THE TECHNICAL PROBLEM

The classical solution, herein shown in FIG. 1 , for mixing return air into the ingoing air uses one or more sucking ingoing air fans 1 , and one or more pressing off air fans 2 and a mixing part 3. The mixing part 3 consists of three slide valves 4a, 4b, and 4c, which are functionally connected with each other. If the slide valve between the air streams, the return slide valve 4b, is controlled towards an open position, the two other slide valves 4a and 4c, the regulating slide valves for ingoing air and off air, are regulated towards a closed position and vice verse. By calibrating the degree of opening the return airflow is regulated. The positioning of the fans guarantees that the functioning that the return air is pushed from the off air side to the ingoing air side, by means of the pressure situations which will occur between the fans. The fans are driven using a constant number of revolutions. When starting up the air conditioning apparatus the different airflows are adjusted to designed values with the aid of externally positioned closing valves (not shown) at the end positions of the return air slide valve 4b (minimum and maximum return air admixture). Ingoing air flow and off air flow are adjusted when the return air slide valve 4b is closed and the return air flow is adjusted when the return air slide valve 4b is open.

This solution has its drawbacks, inter alia in that the return air passes both fans 1 and 2, and in that the ingoing air flow is constantly controlled by the designed air flow, which is only necessary when a maximum heating effect, or cooling effect, alternatively, is to be distributed. Both causes an unnecessary high use of electrical energy.

SUMMARY OF THE PRESENT INVENTION

The present invention has the aim of solving this problem and in particular to reduce the electrical power required at return air admixture systems in air conditioning equipments.

DETAILED DISCLOSURE OF THE PRESENT INVENTION The present invention relates in particular to an air conditioning equipment for return air admixture of off air into ingoing air, which equipment comprises means for out door air flow, return air flow, off air flow, and ingiong air flow, whereby the equipment is characterized in that the it comprises a. a control and regulating system which comprises a monitoring and calculation unit arranged, based on one or more sensors present in the buiding to individually regulate first and second air flow means, by means of adjustable means, and speed controllable fans to provide a desired return air admixture, b. that a first air flow means is regulated in sequence with a second air flow means, whereby when said second air flow means is regulated to a required degree of opening the first air flow means has ful degree of opening, and when the siad second air flow means has a full degree of opening, then the said first air flow means is arranged to provide a required degree of opening to balance the need for out door air flow and return air flow, c. that the speed of the fan present in the off air flow channel is arranged to be regulated to meet the need for outgoing air flow, d. that the speed of the fan in the ingoing air flow channel is arranged to be regulated to fulfill the need for ingoing air flow, e. a section for return airflow comprising a second air flow means controlled by a adjusting means, which second air flow primarily regulates the return air flow, f. a speed controllable fan in the ingoing air channel and a speed controllable fan in the off air channel, whereby the fan of the ingoing air channel is placed in the air flow direction subsequent to the section for return air flow, g. a first air flow means, which is controlled by a adjusting means , and which primarily regulates the addition of out door air, is placed in the ingoing air stream in the air flow direction prior to the section for return air flow,

h. whereby the fan section of the off air stream is placed in the air flow direction subsequent to the section for return airflow.

In a preferred embodiment the means for return air flow is a sllide valve.

In a preferred embodiment the air conditioning equipment further comprises means for monitoring the ingoing air flow, which means is arranged to provide an output signal to the monitoring and calculation unit to control the ingoing air determined.

In a preferred embodiment the air conditioning equipment further comprises means for measuring the outgoing air flow, which means is arranged to provide an output signal to the monitoring and calculation unit to control the outgoing air determined.

In a preferred embodiment the means for measuring of ingoing and outgoing air flows is arranged at inlets of the fans present in the air conditioning equipment.

In a preferred embodiment the air conditioning equipment further comprises means for measuring one or more of the following aiir flows, viz., outdoor air flow, outgoing air flow, or return air flow, which means is arranged to provide output signals to the monitoring and calculation unit to control the outgoing airflow determined.

In a preferred embodiment the air conditioning equipment further comprises means for measuring two air flows of the outdoor flow, outgoing air flow and the return air flow, which means is arranged to provide output signals to the monitoring and calculation unit to control the outdoor and outgoing air flows determined.

In a preferred embodiment the means for measuring the different airflows are pressure measuring means.

Further aspects of the present invention will be evident from the following detailed description of an embodiment of the present invention with reference to FIG. 2 of the accompanying drawing.

Definitions

The term ingoing air means herein air which is provided to a ingoing air flow to a space.

The term outdoor air means herein the air which is taken from the outside of a building to be ventilated. The term offair means herein the air which is drawn from a space.

The term outgoing air means herein the air which leaves the building which is ventilated.

The term return air means herein that part of the offair which is returned to the ingoing air.

The solution to the problem, cf. FIG. 2, is to mechanically separate and individually regulate the different slide valves and that the offair fan is placed, in the air flow, subsequent to the return air slide valve. The solution can thereby utilize the development of fans and electronics made during the last years, which facilitates an efficient and rational handling of the air. The air conditioning equipment comprises an ingoing air fan 11 arranged in an ingoing air channel 21 , and an offair fan 12 arranged in an offair channel 22. Both ingoing air fan and offair fan are speed controlled and contains equipment 13 to measure air flow. In the ingoing air flow there is an outdoor air slide valve 14, which is provided for adjustable degree of opening. Between the ingoing air flow channel 21 and the offair flow channel 22 there is a return air flow channel 23, which channel 23 is provided with a return air slide valve 15, which is equipped for an adjustable degree of opening. The offair channel 22 is further provided with an outgoing air slide valve 16. A sensor (not shown) is installed to be able to determine the addition of outdoor air. A control program, soft ware, controls and regulates the fans 11 and 12 and the slide valves 14, 15 so that the functioning is secured.

Using the new position of the offair fan there is no guarantee that the return air is driven from the offair side to the ingoing air side by means of the pressure differences which occur in the system. This will now become secured by individually regulating the different slide valves and the speed controlled fans. The effect of the present solution is thereby that the return air will now only pass one fan, the ingoing air fan 11. An estimation gives, if the return air is set to 50% of the off air flow, that the energy demand to the offair fan 12 will be reduced with more than 50%, the

larger return air flow the larger reduction of the energy demand, as the outgoing air is reduced and thereby the speed of the fan 12 of the offair side. Further, the ingoing air can be adjusted to the actual level required so that the air shall be able to distribute the need for heat, or cold, alternatively. To reduce the amount of air means a substantial reduction of the electrical power consumed by a fan and thereby the electrical energy used. Start-upis faciliated as the software guarantees that the equipment is operated with the correect air flows without unneccessary restrictions which means losses.

The air conditioning equipment according to FIG. 2 is controlled by a control and regulating software. By continuously monitoring signals from sensors, which signals are based on the ingoing air, offair, and outdoor air flows, and calculate the respective airflows the control software can control the speed of the fans 11 and 12, and the degree of opening of the out door air slide valve 16 and the return slide valve 14, respectively, to the conditions desired. As an alternative to monitoring and calculating of outgoing air and/or outdoor air flows the offair flow or the return air flow can be used.

The monitoring is normaly made using indirect measurement of pressure which is then transferred into flow. In a control and regulating system all monitoring and calculations as well as regulation of air flows are made via outgoing signals to suitable places. Ingoing air and offair flows are regulated in a most energy efficient way by adjusting the speed of the fans.

The invention is not restricted to the above disclosed example of an embodiment, but modifications are contemplated within the framework of the accompanying claims. For example, a simplified solution may without monitoring sensor signals, be created based on empirically created algorithms.