Designing of Vapour Cycle Cooling System of Twin Seater Basic Trainer Aircraft

This paper presents designing of Vapour Cycle Cooling System (VCCS) for twin seater basic trainer aircraft for Cockpit Air Conditioning. Design specification calls for maintaining cabin mean temperature of 26°C and 50% RH at ambient temperature 40°C & speed 0.4 Mach. Maximum cockpit heat load including condenser & evaporator fan heat loads is estimated as 6.5 KW. At this heat load, to maintain cabin mean temperature of 26°C, there is a need to supply 831.5Kg/hr of air flow into cockpit at a temperature of 5°C. This envisaged VCCS evaporator heat load 8.14 KW as ambient air is sucked by evaporator fan at 40°C. VCCS design calculations with R134fa refrigerant have been carried out in iterative process for final selection of evaporator temperature of -6°C, condenser temperature 60°C with 5°C superheat & compressor work <; 4.8 KW. Control logics have been developed to control the VCCS in all flight regimes.