FORM 2
THE PATENTS ACT. 1970
(39 of 1970)
&
THE PATENS RULES, 2003
PROVISIONAL SPECIFICATION
[See section 10, Rule 13]


AIR CONDITIONING SYSTEM FOR CONTINUOUS HIGH SENSIBLE HEAT LOAD APPLICATION AND METHOD THEREOF
BLUE STAR LIMITED, A COMPANY
INCORPORATED UNDER COMPANIES
ACT 1956, WHOSE ADDRESS IS
KASTURI BUILDINGS, MOHAN T.
ADVANI CHOWK, JAMSHETJI TATA
ROAD, MUMBAI- 400 020
MAHARASTRA, INDIA;

THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION:


FIELD OF THE INVENTION
The present invention generally relates to an air conditioning system for an enclosed
space and particularly, it relates to the air conditioning system used for continuous high sensible heat load application in the enclosed space for example air-conditioning system used for telecom enclosed space applications.
BACKGROND ART OF THE INVENTION:
Traditionally, an air conditioning system for continuous high sensible heat load application comprises a cooling mode system, a free-cooling mode system and a controller. The cooling mode of the system includes a refrigeration circuit which includes a compressor, Condenser coil, Evaporator coil, and an expansion device having a variable opening. The controller selectively operates the system in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via said compressor and in the free-cooling mode by forcefully circulating outdoor-air in the enclosed space. A free-cooling limitation and variation sequence resides on said controller.
In general, free cooling mode is used when the outdoor-air temperature is comparatively lower than the specified temperature inside the enclosed Space. During free cooling, the cooling mode system is automatically switched-off and outdoor air is forcefully allowed-in by using evaporator fan or any other separate fan for this purpose, thereby maintaining the enclosed space temperature within specified limits. The airflow of this fan of the present air conditioning systems is fixed irrespective of the outdoor temperature.
However, when the outside temperature is too low or below 0 Deg C, the continuous running of free cooling may cause damage to the Telecom Products / Instruments working in the specified enclosed space.

DESCRIPTION OF THE INVENTION
An object of the present invention is to provide an air conditioning system to obviate
above shortcoming.
According to one embodiment, the present invention provides an air conditioning system for continuous high sensible heat load application comprising a cooling mode system including a refrigeration circuit having a compressor, a condenser coil, evaporator coil, an expansion device having a variable opening connected in the required order, a free-cooling mode system having a fan and a damper for directing air-flow adapted on an inlet for outer air, and a micro-controller wherein said micro¬controller controls the fan speed and/or opening of the damper when the system operates on the free-cooling mode in order to control air flow for maintaining the temperature of the enclosed space within a predefined range. In another embodiment, the present invention provides a method for maintaining the temperature within the predefined range by using an air-conditioning system comprising a cooling mode and a free cooling mode. Said method comprises steps of: checking the ambient temperature and room temperature; operating the system in the cooling mode if the enclosed space temperature is above the higher set point of predefined temperature range and less than the outside temperature or in free cooling mode if the enclosed space temperature is above the outside temperature and above the set point; wherein the method comprises a step of controlling air-flow of out side entering in the enclosed space during the free-cooling mode in order to control air flow for maintaining the temperature of the enclosed space within a predefined range.
The method also includes a step of stopping the free cooling if the temperature of the enclosed space decreases below the lower set point to maintain the temperature of the enclosed space within the defined range.
According to the present invention, the air flow intake is controlled by controlling the fan speed and/or opening of the damper during free cooling.

The invention will now be described with reference to figures 1 and 2 in the accompanying Drawings.
Figure 1 shows the general view of the air conditioning system with free cooling mode. It has the following features:
(a) DC operated blower to change speed to save power. Filter to avoid dust infiltration during free cooling.
(b) A damper or flapper for selective inlet and outlet of air.
(c) Refrigeration circuit including compressor, condenser and other refrigeration components.
Figure 2: Shows the flowchart for the microcontroller logic for Intelligent Flow Control for Power Saving
Referring to figure 1, the integrated solution for continuous high sensible heat load application consists of a cabinet (1) wherein a cooling fan or blower (2), a damper (3) controlled by a stepper motor (4), microcontroller box.(5) and a refrigeration circuit (6,7,8,9,10,11)is placed. The refrigeration circuit is placed in the lower half of the cabinet (1) which includes a compressor (6), a condenser coil (7), dryer (8), an expansion valve (9), evaporator coil or cooling coil (10). The condenser coil is cooled by the condenser fan (11).
The Cabinet also consists of four window openings (12, 13, 14, 15) for exchange of the air. Two window openings (12, 13) are on the enclosed space side and the other two (14, 15) are on the atmosphere side. The enclosed space air is brought in into the cabinet (1) through the air inlet window (12). And the cooled air from the cooling coil (10) is passed to the enclosed space through the air outlet window (13) on the enclosed space side. On the atmosphere side there are two windows to take air in (14) (in case of free cooling) and out (15). At this inlet window air filter is placed so as to filter the incoming atmospheric air.
Cooling coil (10) is placed diagonally inside the cabinet (1). The cabinet (1) also consists of a damper or flapper (3) which is operated by a stepper motor (4) which in

turn is controlled by a micro controller placed in the controller box (5). The damper (3) is placed in such a manner that when it is placed in a position A, it allows the fresh air from the atmosphere directly to pass over the cooling coil (10) and the air from the enclosed space is passed out to the atmosphere through the air out window (15) on the atmosphere side. Alternatively, when the damper (3) is in the position B, it cuts off the contact with the atmospheric air and circulates the inside air over the cooling coil (10).
Temperature sensor S1 is placed at air inlet from the enclosed space side (12) to sense the enclosed space air temperature. Temperature sensor S2 is placed on the atmosphere side (14) to sense the ambient air temperature.
Temperature sensor S1 checks the ambient temperature T1 and temperature sensor S2 checks the enclosed space air temperature T2. If the enclosed space temperature T2 is below the set point TS then the compressor (6) is not started. If the temperature T2 is above the set point TS then the condition for any fault signal existing is checked. When there is no fault in the signal then the compressor (6) is started after specified time delay or else if there is some fault existing then emergency free cooling is started with 100% fan speed.
If the ambient temperature T1 is below the free cooling set point TF then by applying certain conditions the fan speed and/or opening of the damper is controlled using the micro-controller logic. For example, the micro controller controls as follows:
a) If the ambient temperature T1 is between 24 and 26 degree then the damper (3) is placed at position A and free cooling starts with 100% fan speed.
b) If the ambient temperature T1 is below 24 and above 20 then the damper (3) is placed at position A and free cooling starts with 60% fan speed.
c) If the ambient temperature T1 is 20 degree then the damper (3) is placed at position A and free cooling starts with 40% fan speed.

d) If the ambient temperature is 19 degree or below then the damper (3) is placed at
position A and free cooling starts with 40% fan speed for 10 min on cycle and 4 min
off cycle.
If enclosed space temperature T2 reaches low set point TS or Enclosed space
temperature T2 reaches to set point TS or Enclosed space temperature T2 is set
point TS + 1 degree for more than 10 minutes, the free cooling is stopped or else if,
the above conditions mentioned don't prevail the free cooling is continued.
Once free cooling is stopped the ambient temperature T1 and enclosed space
temperature T2 are checked again for accessing the enclosed space temperature
being below the set point or not.
The advantage of the present invention that it provides an improved free cooling
system for enclosed space, saves electrical energy cost and enhance motor life,
controls the air flow amount, when the outdoor air temperature is too low or below 0
deg C and does not affect the performance of Telecom products / Electronic
Instrument kept inside the enclosed space, and also restrict the infiltration of dust by
providing filter in the free cooling system, thus improve the performance and enhance
the life of the products / instruments kept inside.
Dated this 1st day of December, 2008.