FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
SYSTEM AND METHOD FOR MONITORING PERFORMANCE OF A CHILLER UNIT;
BLUE STAR LIMITED A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS KASTURI BUILDINGS, MOHAN T. ADVANI CHOWK, JAMSHETJI TATA ROAD, MUMBAI - 400 020, MAHARASHTRA, INDIA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE INVENTION
The invention relates to a chiller unit. More particularly to a system and method for monitoring performance of a chiller unit.
BACKGROUND OF THE INVENTION
Typically, a chiller unit comprises a compressor, a condenser and an evaporator, wherein, the compressor compresses gaseous refrigerant, and the condenser liquefies the compressed gas, and the evaporator in which the liquid refrigerant evaporates prior to returning to the compressor and chills the chilling liquid.
To measure performance of the chiller unit parameters like load of the chiller unit, temperature of the refrigerant, and flow rate of the refrigerant are measured. All these parameters are measured manually. Manual methods suffer from inherent disadvantages such as time consuming, complicated, erroneous readings, repetition of steps, inaccuracy of recorded data, etc. Due to inaccuracy of measured parameters, performance of the chiller unit cannot be measured continuously or cannot be monitored.
Further, flow meters are used to measure flow rate. However, the flow meters are expensive, difficult to mount in a compact plan room, and difficult to integrate with chiller units. Further to this maintenance cost of the flow meter is also high. Furthermore, flow meters cannot detect fouling in the chiller unit due to less flow or bad fluid quality.
In view of the above, there is a need for a method and system for monitoring performance of a chiller unit that solves at-least one of the problems referred above.

SUMMARY OF THE INVENTION
Accordingly, the present invention in one aspect provides a system for monitoring performance of a chiller unit, the system comprising of a first and second temperature sensor connected at an inlet line and outlet line of a evaporator unit for measuring temperature difference between the inlet and outlet, fluid ; a differential pressure sensor connected between the inlet and outlet of the evaporator unit for measuring flow rate of the fluid; a load sensor for detecting load of the chiller unit; a controller unit, the controller unit receives input from the temperature sensors, the differential pressure sensor and the load sensor for calculating the performance of the chiller unit; and a display device for displaying the determined performance parameter, wherein the performance parameter is displayed depending upon a predetermined temperature set point thereby providing performance of the chiller system.
In another aspect, the present invention provides a method for monitoring performance of a chiller unit, the method comprising the steps of measuring temperature difference between inlet fluid and outlet fluid of an evaporator of the refrigeration system using temperature sensors; measuring differential pressure of the fluid flowing through the evaporator using a differential pressure meter; detecting power consumption of the refrigeration system; calculating performance parameter based upon the measured temperature, flow rate and power consumption by a controller unit; and displaying the determined performance parameter on a display device, wherein the performance parameter is displayed depending upon a predetermined temperature set point thereby allowing monitoring performance of the chiller system.

BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows a schematic flow diagram of a chiller unit according to the present invention; and
Figure 2 shows a schematic view of a differential pressure sensor according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
Various embodiments of the present invention provide a system and method for continuously monitoring performance of a chiller unit.
Figure 1 shows a chiller unit 100 according to the present invention. The chiller unit 100 comprises a condenser 110, a compressor 120, an evaporator 130, an inlet temperature sensor 132, an outlet temperature sensor 134, a differential pressure sensor 140, and a controller 150, wherein the temperature sensors T1, T2, the differential pressure sensor 140 and the load sensor are used for monitoring performance of the chiller unit..
The compressor 120, condenser 110, and evaporator 130are connected in series, and function in a known way. According to the present invention, the evaporator 130 and the condenser 120 are shell and tube type.
The inlet temperature sensor 132 and the outlet temperature sensor 134 are connected to the inlet line and outlet line of the evaporator 130 as shown in the figure 1 and 2. The inlet temperature sensor 132 measures temperature T1 of inlet fluid, and the outlet temperature sensor 134 measures temperature T2 of outlet fluid. Further to this the controller 150 evaluates the temperature difference (T2-T1) of the fluid flowing from the inlet line to the outlet line of the evaporator 130.
The differential pressure sensor 140 is connected between the inlet line and outlet line of the evaporator 130 as shown in figure 2. The differential pressure sensor 140 measures flow rate of the fluid flowing through the evaporator 130. In this regard, the differential across fluid measured by the differential pressure sensor 140 is provided to the controller 150. The controller 150 maps/matches the differential

across the fluid to a corresponding flow rate value, thereby providing an accurate reading of the flow rate. Furthermore, the differential pressure sensor 140 is capable of detecting and indicating pressure drop or fouling in the chiller unit 100 due to less flow or bad fluid quality. Advantageously, the differential pressure sensor 140 obviates the use of flow meters and the disadvantages associated with use of flow meters.
Further, the system included a load sensor (not shown) for detecting power consumption of the chiller unit 100.
The controller 150 receives input from the temperature sensors T1, T2, the differential pressure sensor 140 and the load sensor for calculating the performance of the chiller unit and output the performance of the chiller unit on a display unit 160.
The display unit 160 is connected with the controller 150 and is configured to display the performance of the chiller unit in a condition only when temperature of the chiller unit reaches a predetermined temperature set point. In this regard the predetermined temperature set point is stored in the controller and can be changed as per user requirement. According to the present invention, the display unit 160 is a touch screen display device providing access to the controller.
In an embodiment, the present invention provides a method for monitoring performance of a chiller unit, the method comprising the steps of measuring temperature difference, measuring differential pressure, detecting power consumption of the refrigerant system, calculating performance parameter based upon the measured temperature difference, flow rate and power consumption and displaying the determining performance parameter.

The step of measuring temperature difference includes measuring temperature difference between inlet fluid and outlet fluid of a chiller of the refrigeration system using temperature sensors.
The flow rate of the fluid is also .measured across the evaporator using a differential pressure meter.
Further the power consumption of the refrigeration system is also detected.
Once the temperature difference, flow rate and power consumption is measured, a controller evaluates performance parameter based upon these measured parameters, and displays it on a display device. According to the present invention, the performance of the chiller system is evaluated by the following formulae:
Performance of the Chiller System = 3.516 / (KW/TR),
Where,
KW is the Power consumption, and
TR is the Actual cooling capacity = (T2 in F - T1 in °F) * (Flow Rate in USGPM)
24
Where,
T1 is Temperature of Inlet fluid of Evaporator T2 is Temperature of Outlet fluid of Evaporator
The performance of the chiller unit is displayed only when temperature of the chiller unit reaches a predetermined temperature set point, which is stored in the controller. According to the present invention, the performance of the chiller unit is display based upon the following formulae:

Display of Performance of Chiller System = T2+ Monitoring Constant Example:-
Assume , Running set-point/constant "T2" = 44°F and Monitoring constant = 5°F
The above values are available in controller, and the COP monitoring temperature in F is =T2+ Monitoring Constant= 44+5=49
The performance of the chiller unit will be displayed only after reaching "T2" value as 49 F.
According to the present invention, the chiller unit will have a pre-determined set point depending upon specification of the chiller unit. The pre-determined set point is flexible and can be changed as per user requirement through the controller. The set pre-determined set point (for e.g. 49°F) will ensure that a stable and close to design condition of the chiller unit is reached before the performance parameter is displayed.
Advantageously, the present invention provides a system and method for continuously monitoring performance of a chiller unit which is accurate.
While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims:

WE CLAIM:
1. A method for monitoring performance of a chiller unit, the method comprising
the steps of:
measuring temperature difference between inlet fluid and outlet fluid of an evaporator of the refrigeration system using temperature sensors;
measuring differential pressure to provide flow rate of the fluid flowing through the evaporator using a differential pressure meter;
detecting power consumption of the refrigeration system;
calculating performance parameter based upon the measured temperature, flow rate and power consumption by a controller unit; and
displaying the determined performance parameter on a display device,
wherein the performance parameter is displayed depending upon a predetermined temperature set point thereby allowing monitoring performance of the chiller system.
2. The method as claimed in claim 2, wherein the predetermined temperature set point is stored in a controller.
3. A system for monitoring performance of a chiller unit having an evaporator, a compressor, and a condenser device arranged in series, the system comprising of:
a first and second temperature sensor connected at an inlet line and outlet line of the evaporator for measuring temperature difference between the inlet and outlet fluid ;

a differential pressure sensor connected between the inlet and outlet of the evaporator for measuring flow rate of the fluid;
a load sensor for detecting load of the chiller unit;
a controller unit, the controller unit receives input from the temperature sensors, the differential pressure sensor and the load sensor for calculating the performance of the chiller unit; and
a display device for displaying the determined performance parameter,
wherein the performance parameter is displayed depending upon a predetermined temperature set point thereby providing performance of the chiller system.
4. The system as claimed in claim 3, wherein the controller stores the predetermined temperature set point.
5. The system as claimed in claim 3, wherein the display device is a touch-screen display device.