Absorption heat pump, Microchannels, Wick
Novel microchannel absorbers have been scaled-up and incorporated into a 5-kW-scale ammonia-water absorption heat pump. The planar microchannel absorbers operate with thin wick structures to enhance mass transfer in the absorption channels which are interleaved with microchannel heat exchange layers. The resulting rapid heat and mass transfer facilitates significant size reduction in the absorber and consequently the overall heat pump system. Based on the 5-kW-scale system design, up to 50% size reduction relative to current commercial equipment is projected. The microwick absorber technology is described and measured performance data are provided for proofof- concept single-channel devices up to multi-channel devices tested in a 300 Watt breadboard. The design of 5 kW system includes a unique configuration of components to enable high COP exceeding 0.5 at military conditions of 50°C ambient temperature. The 5 kW system design is discussed and performance data are provided from initial laboratory testing. Cost of the microwick components is expected to be higher than conventional equipment. Volume sensitive cost estimation models are described that have been used to predict the manufactured costs of the microwick absorber devices. The resulting cost-volume curves provide insights into the potential trade-off between size and system cost.