Chiller Systems

Waste Heat Fired Absorption Chillers - Hot Air

General

Direct-fired absorption chillers can often be modified to accept hot air or exhaust from a gas turbine or engine. Performance is almost totally dependent upon air temperature, For example, waste heat air temperatures °F or higher offer performance similar to direct-fired absorption chillers where every 13,000 Btu of heat recovered produces one ton of cooling. When calculating heat recovery, remember to assume waste heat leaving the absorption chiller at 375° to 400°F (this means the absorption chiller will not reclaim all of the waste heat potential).

For exhaust gas heat recovery

Chilling capacity (tons) = m x (Tg - 375)

40,950

Heating capacity (BTUH) = m x (Tg - 375) x 0.257

where m = exhaust gas flow rate in pounds per hour

Tg = exhaust gas inlet temperature in °F

40,950 = cooling constant representing average gas specific heat, interconnect efficiency, cooling COP and the conversion from BTUH to tons

0.257 = heating constant representing average gas specific heat and the interconnect efficiency

375 = minimum temperature of exhaust gas leaving chiller in °F.