In-situ Measurement of Absorption Rates in Horizontal-Tube Falling-Film Ammonia-Water Absorbers: Part Ⅱ - Heat and Mass Transfer Coefficients

摘要

An experimental investigation of heat and mass transfer in a horizontal-tube falling-film ammonia-water absorber was conducted. A tube bank consisting of four columns of six 9.5 mm nominal OD, 0.292 m long tubes was installed in an absorber shell that allowed heat and mass transfer measurements and optical access for flow visualization. This absorber was installed in a test facility consisting of all the components of a functional absorption chiller, which was fabricated to obtain realistic operating conditions at the absorber to account for the influence of the other components in the system. Tests were conducted over a wide range of operating conditions (nominally, desorber solution outlet concentrations of 5 - 40% for three nominal absorber pressures of 150, 345 and 500 kPa, over solution flow rates of 0.019 - 0.034 kg/s.) The development of the test facility, and the measurement and analysis techniques were discussed in the companion paper (Part Ⅰ). Results, including the component level heat transfer rates, and solution- and vapor-side heat and mass transfer coefficients, are discussed in this paper. The effects of solution flow rate, concentration, and pressure on heat and mass transfer coefficients are discussed.