Measurement of absorption rates in horizontal-tube falling-film ammonia-water absorbers

Lee, Sang-Soo; Bohra, Lalit Kumar; Garimella, Srinivas; Nagavarapu, Ananda Krishna

doi:10.1016/j.ijrefrig.2011.08.011

Cited by 30 publications

(13 citation statements)

References 22 publications

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“…This is confirmed by the temperature measurements taken along the tube array, which indicate subcooling ranging between 5 and 20 °C. A similar observation was noted by Lee et al [14] who also conducted experiments under realistic operating conditions. Chen and Christensen [32] previously observed that the absorption process can be decomposed into two basic processes: absorption owing to subcooling of liquid solution in the absence of external cooling, and absorption into saturated solution cooled externally at the wall.…”

Section: Discussionsupporting

confidence: 84%

“…Other properties such as enthalpy and specific volume can be estimated once the state of the mixture is completely defined. A step-by-step procedure describing this data reduction analysis is provided elsewhere [14]. At the absorber, measured mass flow rates and calculated enthalpies of the three working fluid streams are used to calculate the solution-side heat duty.…”

Section: Discussionmentioning

confidence: 99%

“…Figures 3 and 4 show a schematic and photograph of the test facility, respectively. The overall test facility and the testing procedures are described in detail elsewhere [14,15]. A brief overview is provided here.…”

Section: Fig 2 Schematic Of Microchannei Absorbermentioning

confidence: 99%

“…Other studies were conducted at unrealistic vapor and solution concentrations, in addition to the unrealistic absorber pressures, such as a vapor concentration of 64.7-79.9% [12], and vapor and solution concentration of 63-11% and 1.2-2.2%, respectively [13]. A notable exception is the study conducted by Lee et al [14,15], where ammonia-water falling-film absorption on horizontal tubes was studied over a range of pressures, concentrations, and flow rates, on a test facility replicating a functional absorption chiller. Their study confirms the importance of the parameters discussed above on the absorption heat and mass transfer process.…”

Section: Introductionmentioning

confidence: 99%

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Falling-Film Absorption Around Microchannel Tube Banks

Nagavarapu

Garimella

2013

Journal of Heat Transfer

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An experimental investigation of heat and mass transfer in a falling-fllm absorber with microchannel tube arrays was conducted. Liquid ammonia-water solution flows in a falling-fllm mode around an array of small diameter coolant tubes, while vapor flows upward through the tube array counter-current to the falling fllm. This absorber was installed in a test facility consisting of all components of a functional single-effect absorption chiller, including a desorber, rectifler, condenser, evaporator, solution heat exchanger, and refrigerant precooler, to obtain realistic operating conditions at the absorber and to account for the influence of the other components in the system. Unlike studies in the literature on bench-top, single-component, single-pressure test stands, here the experiments were conducted on the absorber at vapor, solution, and coupling fluid conditions representative of space-conditioning systems in the heating and cooling modes. Absorption measurements were taken over a wide range of solution flow rates, concentrations, and coupling fluid temperatures, which simulated operation of thermally activated absorption systems at different cooling capacities and ambient conditions. These measurements are used to interpret the effects of solution and vapor flow rates, concentrations, and coupling fluid conditions on the respective heat and mass transfer coefficients.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Fig 2 Schematic Of Microchannei Absorbermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Falling-Film Absorption Around Microchannel Tube Banks

Nagavarapu

Garimella

2013

Journal of Heat Transfer

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“…Lee et al [17] evaluated an absorber with a tube bank of four columns of six 9.5 mm nominal OD, 0.292 m long tubes installed in a shell in order to quantify the heat and mass transfer measurements for ammonia/water mixtures. For the range of experiments conducted, the absorber heat duty varied from 3.11 to 10.2 kW, the overall heat transfer coefficient varied from 753 to 1853 W·m .…”

Section: Falling Film Absorbersmentioning

confidence: 99%

Performance of Different Experimental Absorber Designs in Absorption Heat Pump Cycle Technologies: A Review

Ibarra-Bahena

Romero

2014

Energies

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Abstract:The absorber is a major component of absorption cycle systems, and its performance directly impacts the overall size and energy supplies of these devices. Absorption cooling and heating cycles have different absorber design requirements: in absorption cooling systems, the absorber works close to ambient temperature, therefore, the mass transfer is the most important phenomenon in order to reduce the generator size; on the other hand, in heat transformer absorption systems, is important to recover the heat delivered by exothermic reactions produced in the absorber. In this paper a review of the main experimental results of different absorber designs reported in absorption heat pump cycles is presented.

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