HVAC Vapor Absorption Systems: Fundamentals and Applications

A: Push the wrong lever here and you’ll lose cooling fast, then chase it into a trip. Higher absorber temperature cuts absorption, pressure rises, and refrigerant flow collapses. Dropping load reduces vapor generation and stabilises pressures. Increasing chilled water flow or generator heat just deepens the imbalance and risks crystallisation.

A: Undersizing the heat source means the machine never reaches rated tonnage and fails SAT. COP is defined as cooling divided by generator heat, so you divide 500 kW by 0.7. Mixing in heat rejection or assuming symmetry gives the wrong order of magnitude.

A: Greenlighting this without enough heat leaves you with a half-capacity plant and angry operations. Single-effect machines at ~95°C run COPs around 0.6–0.7, so 1 MW of cooling needs roughly 1.4–1.6 MW of heat. Temperature alone doesn’t pay the energy bill.

A: Misdiagnose this and you’ll clean the wrong heat exchanger while capacity stays lost. Low generator input means less refrigerant vapor reaches the evaporator, dropping pressure and cooling effect. Absorber or condenser faults usually push pressures up, not down.