FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENS RULES, 2003
COMPLETE SPECIFICATION [See section 10, Rule 13]
AIR CONDITIONING SYSTEM FOR COLD STORAGE OF SEEDS AND METHOD THEREOF;
BLUE STAR LIMITED, A COMPANY
INCORPORATED UNDER
COMPANIES ACT 1956, WHOSE ADDRESS (S KASTURI BUILDINGS, MOHAN T. ADVANI CHOWK, JAMSHETJI TATA ROAD, MUMBAI-400 020 MAHARASTRA, INDIA;
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT HAS TO BE PERFORMED:

FIELD OF INVENTION
The present invention generally relates to an air conditioning system for cold storage of seeds and a method thereof.
BACKGROUND OF THE INVENTION
The Farmers and seed producers are known to carry over and store seed from one wet season to another. Long periods of hot, humid weather lead to the rapid deterioration of stored seed or grain generally affecting seed viability. Factors that influence the longevity of stored seed include field conditions where the seed crops are grown, the drying conditions and storing conditions. The most important storage conditions are temperature and relative humidity.
High moisture content in seeds is the main cause for loss of seed viability and vigor. High moisture causes heating, fungal activity (molding) and encourages increased insect activity. Further, early harvested and high moisture content seeds generate heat when they are left in bulk. Conventionally, the seed can be spread out to dry, or preferably dried by blowing unheated or heated air through it. Unheated air is effective if the relative humidity of the air is lower than the equilibrium moisture content of the seed, which is generally done during the dry season. The temperature and relative humidity (RH) of the store are the most important factors affecting seed quality.
Under ideal storage conditions, both RH and temperature should be kept low. Seeds are hygroscopic, that is they absorb moisture from wet air and lose moisture to dry air. Maintaining safe moisture content for storage requires a corresponding low RH, which can be achieved by -

a) Building the storage facility in a location where RH is naturally low.
b) Storing dry seed in impervious sealed containers e.g. sealed tins or drums, thick plastic bags or bottles.
c) Reducing the RH to a favorable level by conditioning the storage environment with refrigeration and dehumidification.
According to the "THUMB RULES" for seed storage, when seed moisture content is between 5% and 14%, each 1% reduction in moisture content approximately doubles seed storage life. Also, when storage temperature is between 0°C and 50°C, each 5°C decrease in storage temperature approximately doubles seed storage life.
Generally, presently the seeds are stored in a well insulated storage room with refrigeration and dehumidification equipment.
However, presently available insulated storage room with refrigeration and dehumidification equipment fails to maintain desired condition for seed storage. Further, it is imperative that precise temperature & RH is maintained within the specified limits, but it is difficult to maintain these conditions as their values can fluctuate at any levels.
SUMMARY OF THE INVENTION
The present invention provides an air conditioning system for cold storage of seeds comprising a refrigeration system including an indoor unit having at least one compressor, a thermostatic expansion valve and an evaporator coil arranged in order and an outdoor unit having a primary condenser coil; at least one temperature sensor for determining temperature condition; at least one electric heater adapted for raising temperature; a solenoid valve

dividing the evaporator coil into a cooling coil and a dehumidification coil; a controller configured for temperature, relative humidity and pressure control and accordingly operating the solenoid valve to handle refrigerant flow through the cooling coil and the dehumidification coil for causing apparatus dew point temperature to drop for achieving higher rate of condensation or maintaining the temperature of the air within the predetermined range. As per one exemplary embodiment the air-conditioning system of the present provides a secondary condenser/reheat coil adapted in the indoor unit of the system parallel to the condenser coil for routing gas discharged from the compressor directly through the secondary condenser coil and preventing temperature from dropping below a set point by passing air stream over the secondary condenser coil.
In one related aspect, the present invention provides a method for operating the air-conditioning system under dehumidification condition, the method comprises steps of: passing the refrigerant through primary condenser coil during normal cooling operation; closing the solenoidal valve adapted on the evaporator coil to block refrigerant flow through cooling coil and directing the refrigerant flow through the dehumidification coil causing apparatus dew point temperature to drop for achieving higher rate of condensation when humidity of the air increase above predetermined humidity range; heating air with electric heater coil for increasing the temperature when the temperature falls below the predetermined temperature range thereby maintaining air within predetermined temperature and humidity range. As per the exemplary embodiment of the method of the present invention, the compressor discharged gas is routed through a secondary condenser

coil when dehumidification is required at attained set point temperature and a heated air stream is passed over the secondary coil to prevent temperature drop.
DESCRIPTION OF THE DRAWINGS
The features, aspects and other advantages of the present invention will
become better understood when the following detailed description is read
with reference to the accompanying drawings in like characters represent
like parts throughout the drawings, wherein:
Figure 1 show an air-conditioning system unit.
Figure 2 shows an air-conditioning system operating under normal
operation.
Figure 3 shows an air-conditioning system with secondary condenser
coil/reheat coil.
Figure 4 shows a single customized system as a complete package to
Control Room environment.
DESCRIPTION OF THE INVENTION
The object of the present invention is to obviate the shortcomings associated with achieving substantially ideal conditions for seed storage by providing an air conditioning system for cold storage and method thereof.
As per one embodiment the present invention describes an air conditioning system for cold storage of seeds comprising a refrigeration system including an indoor unit having at least one compressor, a thermostatic expansion valve and an evaporator coil arranged in order and an outdoor unit having a primary condenser coil; at least one temperature sensor for determining

temperature condition; at least one electric heater adapted for raising temperature; a solenoid valve dividing the evaporator coil into a cooling coil and a dehumidification coil; a controller configured for temperature, relative humidity and pressure control and accordingly operating the solenoid valve to handle refrigerant flow through the cooling coil and the dehumidification coil for causing apparatus dew point temperature to drop for achieving higher rate of condensation or maintaining the temperature of the air within the predetermined range.
As per one exemplary embodiment the air-conditioning system of the present provides a secondary condenser/reheat coil adapted in the indoor unit of the system parallel to the condenser coil for routing gas discharged from the compressor directly through the secondary condenser coil and preventing temperature from dropping below a set point by passing air stream over the secondary condenser coil.
As per another embodiment of the present invention a method for operating the air-conditioning system comprises steps of: passing the refrigerant through primary condenser coil during normal cooling operation; closing the solenoidal valve adapted on the evaporator coil to block refrigerant flow through cooling coil and directing the refrigerant flow through the dehumidification coil causing apparatus dew point temperature to drop for achieving higher rate of condensation when humidity of the air increase above predetermined humidity range; heating air with electric heater coil for increasing the temperature when the temperature falls below the predetermined temperature range thereby maintaining air within predetermined temperature and humidity range.

As per one another additional embodiment the compressor discharged gas is routed through a secondary condenser coil when dehumidification is required at attained set point temperature and a heated air stream is passed over the secondary coil to prevent temperature drop.
FIG. 1 shows an air conditioning system for cold storage (100) according to the present invention comprising at least one compressor (10), an evaporator coil (20), a thermostatic expansion valve (70), a solenoid valve (60), a primary condenser coil (50), electric heaters (30), a suction pressure regulator (40), an accumulator (80), a controller (90) for controlling the temperature, pressure and humidity conditions, a motor (92) and a blower (94).
According to the present invention the evaporator coil (20) comprises a cooling coil (22) and a dehumidification coil (24) wherein the gas which passes from the thermostatic expansion valve (70) is divided into these coils. Generally, the evaporator coil (20) is divided into the cooling coil (22) having one-third area and dehumidification coil (24) having two-third for the dehumidification.
According to the present invention and as shown in FIG. 2, the solenoid valve (60) is adapted in the evaporator coil (20). Alternatively, any other means can be used to operate the evaporator coil (20) as mentioned herein after. The solenoid valve (60) is open during normal operation. When there is rise in humidity levels and dehumidification is required, a method of dehumidification is employed wherein the solenoid (60) gets closed and blocks the refrigerant flow through the cooling coil (22) and directs the total

refrigerant through the dehumidification coil (24) and thereby reducing the total coil area utilized keeping the refrigerant quantity same causing the ADP (Apparatus Dew Point) temperature to drop and getting higher rate of condensation.
According to one embodiment, the air conditioning system (100) may comprise two compressors to provide higher uptime and power reduction.
As per another embodiment of the present invention, the electric heaters (30) are adapted to quickly raise the temperature to get it near the set point when the temperature falls below the set point. The drop in temperature is determined by the temperature sensors. According to a further embodiment, depending on the requirement the heaters (30) can be operated in stages or in proportional mode by utilizing solid state relay.
As per another embodiment of the present invention, in the air conditioning system (100) shown in FIG. 3, an additional secondary condenser coil (55) may be adapted on the indoor side of the system. In a method to achieve dehumidification, the gas discharged from the compressor (10) is routed through a secondary condenser coil (55) and the coil outlet goes in the liquid line before the expansion valve (70) whereby temperature is not allowed to fall below set point. The secondary condenser coil (55) is utilized when the set point for predefined temperature is achieved but the predefined humidity is not achieved. At that time, the air conditioning system (100) runs on the dehumidification which results in dropping down the humidity at predefined level and the temperature below set point. Then air is passed over the secondary condenser coil (55) to increase the temperature at set point. So

the secondary condenser coil (55) comes into operation whereby heat is added into the air stream after the cooling & dehumidification coil (24) and temperature does not drop below the set point, at the same time humidity drops down. Optionally secondary compressor may be used to achieve dehumidification.
As per one embodiment of the present invention, the air conditioning system (100) further comprises of a suction pressure regulator (40) to prevent coil frosting which may result in the tripping. In an essential aspect, to avoid tripping a method is employed whereby, the suction pressure is build up by using CPCE or suction pressure regulator (40) and the accumulation of frost on the coil is avoided. As shown in the diagram the suction pressure regulator (40) bypasses discharge gas to the evaporator coil (20) inlet to remove the frost on the coil and at the same time maintain the suction pressure. The discharge gas at higher pressure and higher temperature causes the coil temperature to rise, which results in removal of frost on the cooling coil (22). The rise in temperature further causes the suction pressure to build up and thereby avoiding the tripping of the compressor (10). In a related indicating aspect, the pressure regulator (40) takes suction pressure as reference for its operation and it can be set mechanically. CPCE constantly monitors the suction pressure on the suction line.
In a related aspect, as shown in FIG. 4; the controller is incorporated for temperature, relative humidity and pressure control of the entire system wherein the controller can be a microprocessor based PID (Proportional integral derivative) controller.

In a related aspect, for tow temperature and low pressure operations shooting up of humidity level and maintaining optimum suction pressure is desired. At lower suction pressures there is possibility of liquid refrigerant returning to the compressor (10), to avoid such a situation an accumulator (80) is incorporated between the cooling coil (22) and suction port of the compressor (10). The liquid along with the refrigerant comes from the inlet of the accumulator and liquid being heavier settles down at the bottom of the accumulator whereas vapor rises at the top and is sucked in through the suction port of the compressor (10), this prevents any liquid from returning to the compressor (10).
As an advantageous aspect the present invention provides a single customized system as a complete package to Control Room environment for seed storage and preservation for short term and intermediate term. In addition to that it maintains the temp of the storage room within +/- 1°c of the set value and RH within & +/- 5% of set value. According to one embodiment, the minimum temperature that can be achieved by this unit is 10°C and the RH up to 40% can be achieved.
The specific arrangement in the present invention leads to the precise temperature and relative humidity control of about 1°C and 5% respectively. Hence, it is possible to maintain the temperature and humidity at desired levels with lowest fluctuations which makes substantially ideal condition for seed storage. The arrangement further includes localized air drops through ducts thereby eliminating high temperature and humidity pockets.

In another advantageous aspect, the system is further accomplished for high static pressure operations and does not require desiccants as in conventional systems.
As a further advantage, when dehumidification is required at attained temperature, it is desired that the compressor (10) should run and at the same time not allowing the temperature to fall further. This is achieved by utilizing the secondary condenser coil (55).
As an additional feature to rapid dehumidification circuit for faster humidity drop, integrated heat recovery for dehumidification and prevention of atmospheric heat loss is also possible.
As another additional advantage of the present invention, the return air from the air-conditioning unit is reconditioned, maintaining temperature and humidity, thereby eliminating any fresh air requirement.
Further, the unit is suitable for various outdoor ambient without any variation in Capacity. The Condenser of the system is facilitated with auto discharge pressure detection and fan speed variation. Further, the condenser is operational at a varied range of outdoor conditions.
The air-conditioning unit of the present invention also occupies less carpet size and total volume compared to conventional air conditioning devices for cold room purposes. In case of multiple Units, the combination feature of auto recognition and run time equalization for all attached units is also incorporated.

While the present invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes can be made in respect of dehumidification, without departing from the scope of the present invention. In addition, many modifications can be made to adapt a particular geometry or dimension to the teachings of the description without departing from the scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the invention will include all embodiments falling within the scope of the appended claims.

We Claim
1. An air conditioning system for cold storage of seeds comprising:
a refrigeration system including an indoor unit having at least one
compressor, a thermostatic expansion valve and an evaporator coil
arranged in order and an outdoor unit having a primary condenser
coil;
at least one temperature sensor for determining temperature
condition;
at least one electric heater adapted for raising temperature;
a solenoid valve dividing the evaporator coil into a cooling coil and a dehumidification coil;
a controller configured for temperature, relative humidity and pressure control and accordingly operating the solenoid valve to handle refrigerant flow through the cooling coil and the dehumidification coil for causing apparatus dew point temperature to drop for achieving higher rate of condensation or maintaining the temperature of the air within the predetermined range.
2. An air-conditioning system as claimed in claim 1, further comprising a
secondary condenser/reheat coil adapted in the indoor unit of the system
parallel to the condenser coil for routing gas discharged from the
compressor directly through the secondary condenser coil and
preventing temperature from dropping below a set point by passing air
stream over the secondary condenser coil.

3. An air-conditioning system as claimed in claim 1, further comprising a suction pressure regulator to avoid tripping due to accumulation of frost on coil.
4. An air-conditioning system as claimed in claim 1, further comprising an accumulator for preventing return of liquid refrigerant to compressor under low temperature condition.
5. An air-conditioning system as claimed in claim 1 wherein a condenser fan of outdoor unit operates at desired varying speeds.
6. An air-conditioning system as claimed in claim 3, wherein the suction pressure regulator bypasses discharge gas to the evaporator coil inlet for removing the frost on the coil and at the same time maintaining the suction pressure.
7. An air-conditioning system as claimed in claim 4, wherein the accumulator is adapted between the cooling coil and the compressor.
8. An air-conditioning system as claimed in claim 1, wherein the indoor unit preferably comprises two compressors for power reduction and to achieve higher uptime.
9. An air-conditioning system as herein described with reference to the foregoing description and the accompanying drawings.

10. A method for operating the air-conditioning system as claimed in claim 1,
said method comprising steps of:
passing the refrigerant through primary condenser coit during normal cooling operation;
closing the solenoidal valve adapted on the evaporator coil to block refrigerant flow through cooling coil and directing the refrigerant flow through the dehumidification coil causing apparatus dew point temperature to drop for achieving higher rate of condensation when humidity of the air increase above predetermined humidity range,
heating air with electric heater coil for increasing the temperature when the temperature falls below the predetermined temperature range;
thereby maintaining air within predetermined temperature and humidity range.
11. An air-conditioning system as claimed in claim 10, wherein for achieving dehumidification at attained set point temperature, the compressor discharged gas is routed through the secondary condenser coil and the air stream is passed over the secondary coil before passing over the evaporator coil
12. An air-conditioning system as claimed in claim 10, wherein the method provides auto discharge pressure detection facilitated in the condenser.

13. A method of operating the air-conditioning system as herein described with reference to the foregoing description and the accompanying drawings.