Refrigeration and Air Conditioning Equipment
This domain tests refrigeration plant and air-conditioning equipment selection, performance and safety: chillers, DX and VRF systems, cooling towers, air-handling units, compressors, refrigerants and part-load behaviour.
Performance metrics
Vapour-compression performance is expressed as COP (cooling kW per input kW), EER (Btu per Wh) or kW/TR, where 1 TR = 3.517 kW and COP = 3.517 / (kW/TR). Compare equipment on part-load figures (IPLV or equivalent) because rated performance occurs rarely. Absorption chillers are judged differently: single-effect machines reach COP around 0.7 and double-effect about 1.2–1.4, but they consume heat, so compare on primary energy and cost, not COP alone. Condenser approach (typically 3–5 K for a clean tower) and evaporator approach indicate fouling and air ingress; superheat and subcooling diagnose charge problems.
Safety and installation
Refrigerants are classified by toxicity and flammability (A1, A2L, B1 and so on). Machinery rooms need the ventilation, leak detection and quantity limits required by the code, and refrigerant must never be vented to atmosphere. Iran is a party to the Montreal Protocol, so R-22 plant is phase-out material and new designs use R-134a, R-410A, R-407C or newer low-GWP alternatives.
Worked example
A chiller delivers 500 kW cooling for 100 kW electrical input: COP = 5.0, EER = 5.0 × 3.412 ≈ 17.1, kW/TR = 3.517 / 5 = 0.70. If the condenser-water pumps draw 37 kW and the tower fans 20 kW, system COP is 500 / (100 + 37 + 20) = 3.18 - a very different number, and the one that matters for energy compliance.
Traps
Mixing kW and TR; quoting gross capacity while ignoring auxiliaries; comparing absorption COP with electric COP directly; forgetting fouling and approach; and specifying refrigerant without checking the room's classification limits.