Refrigeration & Air-conditioning syllabus

Vapour compression systems: Working of simple vapour compression system, representation of vapour compression cycle (VCC) on T-s and P-h diagram, COP (Coefficient of Performance), EER (Energy Efficiency Ratio), SEER (Seasonal Energy Efficiency Ratio), IPLV (Integrated Part Load Value), NPLV (Seasonal Energy Efficiency Ratio), effect of operating parameters on performance of VCC, actual VCC. (Numerical on vapour compression cycle). Vapour absorption systems: Introduction, Working of simple vapour absorption system (VAS), desirable properties of binary mixture (aqua-ammonia), performance evaluation of simple VAS (Simple numerical treatment), actual VAS, Lithium bromide–water absorption system, applications of VAS, comparison between VCC and VAC.

Multistage or Compound Systems: Need of multi staging, two stage compression with flash gas removal, flash intercooler and complete multistage compression system. Multi Evaporator Systems: Single compressor-individual expansion valve, Single compressor multiple expansion valve, Individual compressor-multiple expansion valve, Individual compressor with compound compression and flash inter cooling. (Limited to two evaporators). Ammonia-CO2 cascade cycle. (Only theoretical approach). (Numerical on Multi Evaporator Systems).

Major components of refrigeration systems: Compressors: reciprocating, rotary, screw, and centrifugal compressors. Characteristics and performance comparison. Condensers: Air-cooled, water-cooled, and evaporative condensers. Evaporators: flooded type, dry expansion type, and plate evaporators. Expansion devices: thermostatic expansion valves, capillary tubes, electronic expansion valves. Safety and control devices: LP/HP cut-off controls, frost control, oil pressure failure control, motor overload protection, temperature control devices.

Applied Psychrometry : Psychrometric properties of moist air: dry bulb temperature, wet bulb temperature, dew point temperature, relative humidity, humidity ratio, enthalpy. Psychrometric chart and its use. Psychrometric processes Concepts of Apparatus Dew Point (ADP), Bypass Factor (BPF). Sensible Heat Factor (SHF), Room Sensible Heat Factor (RSHF), Grand Sensible Heat Factor (GSHF), Effective Sensible Heat Factor (ESHF). (Numerical on Applied Psychrometry). Cooling load estimation: Internal heat gains (people, lights, equipment) Solar heat gain through building envelope Ventilation and infiltration loads Methods of cooling load calculation including CLTD/CLF method. Thermal comfort: human comfort parameters, comfort charts, factors affecting comfort. Indoor Air Quality (IAQ): indoor contaminants and methods to improve IAQ. Outdoor design conditions and weather data in HVAC design.

Ventilation: Introduction to Ventilation and infiltration in buildings. Natural ventilation and mechanical ventilation. Air distribution systems and duct design. Duct design considerations including: Duct layout and materials, Pressure losses in ducts, Friction losses in ducts, Equivalent diameter for rectangular ducts (Numerical on Duct design) Methods of duct design: Equal friction method; Static regain method; Velocity reduction method Air distribution components including filters, diffusers, grills, dampers, and fan coil units. Fans used in HVAC systems and fan laws. Modern HVAC systems: VRF (Variable Refrigerant Flow), VAV (Variable Air Volume), Desiccant-based air conditioning, Evaporative cooling systems, Thermal energy storage systems, clean room air conditioning, Radiant cooling systems.