FORM 2 THE PATENTS ACT, 1970
(39 of 1970) & The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Vapour Compression Machine (VCM) for Radar Cooling of Fighter Aircraft.
2. APPLICANT(S)
(a) NAME : HINDUSTAN AERONAUTICS LIMITED
(b) NATIONALITY: INDIAN
(c) ADDRESS : DESIGN MECHANICAL.HAL, NASIK

PROVISIONAL The following specification describes the invention.
X COMPLETE The following specification particularly describes the invention and the manner in which is to be performed.

√
4. DESCRIPTION (Description shall start from next stage.) Refer Annexure l
5. CLAIMS (Not applicable for provisional specification. Claims should start with the preamble - "I/We claim" on separate page) Refer Annexure II
6. DATE AND SIGNATURE (to be given at the end of last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on separate page) Refer Annexure III
Note:-
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*To be signed by the applicant(s) or by authorized registered patent agent.
*Name of the applicant should be given in full, family name in the
beginning.
*Complete address of the applicant should be given stating the postal index
no./code, state and country.
*Strike out the column(s) which is/are not applicable.

Complete Specification of
Vapour Compression Machine (VCM) for radar
cooling of fighter aircraft

1 Title of the Invention
Vapour Compression Machine (VCM) for radar cooling in fighter aircraft
2 Field of the Invention
Present invention refers to design and development of Vapour Compression Machine (VCM) for cooling of very high heat dissipating radar of fighter aircraft with simulation of heat absorption in evaporator (20) portion of VCM and heat rejection at condenser (7) portion of VCM
3 Background of the Invention
Presently Liquid Cooling System (LCS) is used for cooling of existing radar block using coolant solution. Coolant solution circulate inside the transmitter portion of existing radar, absorbs its heat and gets heated up. Heat load of existing radar is moderate of the order of 6.0 to 7.0 KW with high inlet temperature of coolant solution up to 90 °C to 100°C. The cooling requirement of existing radar can be fulfilled by placement of fuel to liquid heat exchanger in coolant loop where fuel (Jet A-1) is used as coolant to absorb the heat of hot coolant solution. The detection range of existing radar is less with moderate detection accuracy. With development of new advanced technology to increase the range of detection and accuracy of detection, existing radar are getting replaced by Active Electronically Scanned Array(AESA) radar having high range and high detection accuracy. Heat load of AESA is high of the order of 10 to 12 KW with low inlet temperature of coolant solution to less than 38 to 40 °C. The cooling requirement of AESA radar cannot fulfil placement of fuel to liquid heat exchanger in coolant loop as fuel temperature during flying of aircraft can reach up to the order of 65 to 70 deg C which cannot bring down the temperature of coolant to less than 38 deg C to 40 deg C. To meet requirement of lower inlet temperature to less than 38 °C, there was a need to design and develop a machine which can bring down the temperature of coolant solution to less than 38 °C. This requirement has

been fulfilled by design and development of VCM with simulation of fuel and coolant loop for radar cooling for fighter aircraft.
4 Brief Summary of the Invention
Vapour Compression Machine. (VCM) (1) has been designed and developed as an invention to cool the higher heat dissipation radar. System designing of VCM and its two main components i.e Evaporator (20) , Condenser(7) has been undertaken. Designing of coolant tank (21), fuel coolant tank (4) and associated pipelines with pressure drop calculations have also been undertaken. System simulation and line replaceable unit (LRU) level simulation has also been undertaken to validate the system design and LRU design of VCM. Test results at critical design points of VCM have been found satisfactory.
5 Detail Description of the Drawings
Figure-1: Drawing of Vapour Compression Machine (VCM) (1) has been evolved as a result of design calculations with respect to inlet flow, inlet pressure and inlet temperature.

Ref. Numerals LRU
1 Vapour Compression Machine (VCM)
2 Coolant to air heat exchanger
3 Stop valve
4 Fuel Coolant tank
5 Fuel Coolant pump
6 Solenoid valve
7 Condenser
8 Drier cum Receiver
9 Temperature sensor
10 High pressure switch

Ref. Numerals LRU
13 Control unit
14 LP Switch
15 Sight glass
16 Expansion Valve
17 Pressure sensor
18 Sensing Bulb
19 Display
20 Evaporator
21 Coolant Tank
22 Coolant pump

Ref. Numerals LRU-
11 Compressor
12 Non Return Valve (NRV)

Ref. Numerals LRU
23 Flow meter
24 Electric heater

6 Detail Description of the Invention
Design and development of VCM (1) with coolant loop at Evaporator portion and Fuel coolant loop at condenser portion has been done in following stages:
A. Stage 1: System design and component design of VCM (1)
B. Stage 2: Component design of Condenser (7) loop portion.
C. Stage 3: Component design of evaporator (20) loop portion.
D. Stage 4: Manufacturing of VCM (1) , Condenser (7) loop portion
and evaporator (20) loop portion system components.
E. Stage 5: Assembly of VCM, Condenser (7) loop portion and
evaporator (20) loop portion system components
F. Stage 6: Functional testing of VCM with Condenser (7) loop portion
and evaporator (20) loop portion system components
Stage 1: System design & component design of VCM
System design & component design of VCM is based on critical design parameter like temperature and flow. VCM is closed loop vapour cycle cooling system where refrigerant is used as working fluid. The heat is removed from liquid cooling system as soon as liquid passes through evaporator (20) unit of VCM. The recirculation of this liquid is a part of Liquid Cooling System (LCS). Heat is absorbed by cold refrigerant at evaporator (20). The compressor (11) of VCS is electrical motor driven

and capable of providing the rated performance. VCM will operate automatically soon after command signal from VCM control unit. Compressor (11) will suck the superheated vapour coming from evaporator (20) and compressed it to condenser (7). Compressed refrigerant will then pass-through condenser (7) where refrigerant will be condensed from vapour to liquid phase by rejecting heat. Refrigerant coming out from condenser (7) is expanded through thermostatic expansion valve (16) to a lower pressure of evaporator (20). Subsequently, refrigerant passes through evaporator (20) at evaporator temperature where it absorbs heat from Liquid Cooling System. Due to heat exchange at evaporator (20) portion, temperature reduces. Constant superheating is provided by evaporator (20) for enabling dry compression. VCM will operate on full load and part load condition
To maintain evaporator (20) pressure with constant degree of superheat, sensing bulb (18) is provided downstream of evaporator (20) which control the opening of thermostatic expansion valve(16) to control the mass flow rate of refrigerant under variable heat load conditions of evaporator(20). Control of VCM under full load / Part load conditions) will be performed by VCM control unit. System design has been optimized at evaporation temperature and condensation temperature. Based on system design mass flow rate of refrigerant in VCM loop has been estimated. Major Components of VCM i.e Evaporator (20) & Condenser (7) have been designed to meet the system design parameters.
iii) Stage 2: System and component design of Condenser (7) loop portion
To absorb the latent heat of condensation at condenser (7) portion of VCM
a coolant is used, condenser (7) portion loop has been designed which
consist of following major components: Coolant pump (5), Coolant Tank
(4), Coolant temperature sensors (9), interconnecting ducts and control
panel(13). Pressure drop calculations have been performed to select

appropriate diameter of interconnecting ducts. Coolant tank (4) size has been decided to take care pulsation dampening and surging.
iv) Stage 3: System and component design of evaporator (20) loop portion
To absorb the latent heat of evaporation (by absorbing heat from radar) at
evaporator portion of VCM, this loop has been designed which consist of
following major components: LCS pump(22), LCS Tank(21), LCS
temperature sensors(9), interconnecting ducts and control panel(13).
Pressure drop calculations have been performed to select appropriate
diameter of interconnecting ducts. LCS tank size has been decided to take
care pulsation dampening and surging.
v) Stage 4: Manufacturing of VCM, Condenser (7) loop portion and evaporator (20) loop portion system components
Manufacturing of VCM, Condenser (7) loop portion and evaporator (20) loop portion system components have been undertaken by selecting appropriate material as per safe design criteria.
vi) Stage 5: Assembly of VCM, Condenser (7) loop portion and evaporator (20) loop portion system components
Assembly of VCM, Condenser (7) loop portion and evaporator (20) loop portion system components has been undertaken as per Figure-1. Airtightness test of VCM, Condenser (7) loop portion and evaporator (20) loop portion have been carried out.
vii) Stage 6: Functional testing of VCM with Condenser (7) loop portion and evaporator (20) loop portion system components
Functional Testing VCM with Condenser (7) loop portion and evaporator (20) loop portion system components has been undertaken at appropriate

Evaporation and Condensation temperature. Cooling of RADAR has been achieved.
An Vapour Compression Machine (VCM) for fighter aircraft is designed as follows using three different loops i.e fuel coolant loop, coolant loop and refrigerant loop . The fuel loop circuit design consisted of fuel coolant to air heat exchanger (2) to cool the fuel heated fuel ,fuel coolant tank (4) used to store the fuel coolant, fuel coolant pump (5) to supply the fuel in the circuit, stop valve (3) for maintenance purpose.
The coolant circuit (LCS) design qonsisted of stop valve (3) for maintenance purpose, coolant tank (21) to store coolant, coolant pump (22) to supply the coolant in the circuit, temperature sensors (9) to measure the temperature of coolant, display (19) to display the temperature and flow reading based on flow meter (23) the electric heater (24) is used to simulate the radar heat load.
The refrigerant loop design using stop valve (3) for maintenance purpose, temperature sensors (9) to measure the temperature of refrigerant, the condenser (7) is used for condensing the refrigerant, a solenoid valve (6) is used for separate high and low pressure lines. The drier cum receiver (8) is used as storage and filtering purpose, low pressure switch (14) for effective operation of compressor (11), sight glass (15) to identify the state of refrigerant, expansion valve (16) to reduce the high pressure to low pressure of refrigerant, pressure sensor (17) is used to measure the pressure of refrigerant, evaporator (20) to remove the heat load from coolant, sensing bulb (18) to sense the degree of super heat, control unit (13) for controlling the function of VCM(1), the high pressure switch (10) cuts-off the compressor (11) above design pressure. The NRV (12) stops the back flow condition of the refrigerant.
The fuel tank (4) is connected to stop valve (3), fuel coolant pump (5) and to condenser (7) through stop valve (3) and returned to fuel tank (4) through heat exchanger (2).

The compressor (11) is connected to condenser (7) through NRV (12 ) and stop valve (3), high pressure switch (10) , temperature sensor (9) and outlet to drier cum receiver (8) through solenoid valve (6) and stop valve (3).
The outlet of drier cum receiver (8) is connected to evaporator (20) through stop valve (3), sight glass (15) , expansion valve (16) and pressure sensor (17); the outlet of evaporator is connected to pressure sensor (9) , sensing bulb (18) to compressor (11) through stop valve (3). The control unit (13) is connected to coolant pump (5), LP switch (14), temperature sensor (9), flow meter (23) electric heater (24) and coolant pump (22) ;
The VCM(1) is used for cooling of very high heat dissipating coolant of radar in an fighter aircraft with simulation of heat absorption in evaporator (20) portion of VCM and heat rejection at condenser (7) portion of VCM.

Claims
We Claim,
1. An Vapour Compression Machine (VCM) for fighter aircraft comprising of:
fuel loop circuit with ;
- fuel coolant to air heat exchanger (2)
- fuel coolant tank (4)
- fuel coolant pump (5)
- stop valve (3) coolant circuit (LCS) having an;
- stop valve (3)
- coolant tank (21)
- coolant pump (22)
- temperature sensors (9)
- display (19)
- flow meter (23)
- electric heater (24) refrigerant loop having;
- stop valve (3)
- temperature sensors (9)

- condenser (7)
- solenoid valve (6)
- drier cum receiver (8)
- low pressure switch (14)
- sight glass (15)
- expansion valve (16)
- pressure sensor (17)
- evaporator (20)
- sensing bulb (18)
- control unit (13)
- compressor (11)
- high pressure switch (10)
- Non Return Valve (12)
fuel tank (4) is connected to stop valve (3) , fuel coolant pump (5) and to condenser (7) through stop valve (3) and returned to fuel tank (4) through heat exchanger (2);
the compressor (11) is connected to condenser (7) through NRV (12 ) and stop valve (3), high pressure switch (10) , temperature sensor (9) and outlet to drier cum receiver (8) through solenoid valve (6) and stop valve (3);
outlet of drier cum receiver (8) is connected to evaporator (20) through stop valve (3), sight glass (15) , expansion valve (16) and pressure sensor (17); the outlet of evaporator is connected to pressure sensor (9) , sensing bulb (18) to compressor (11) through stop valve (3);

the control unit (13) is connected to coolant pump (5) , LP switch (14), temperature sensor (9),flow meter (23) electric heater (24) and coolant pump (22) ;
2. The device claimed in Claim-1 is used to cool the heated liquid in fighter aircraft by fuel coolant as absorbent media at condenser side.