This thesis aims to develop simple and accurate steady-state models of small capacity absorption machines based on experimental data obtained from a solar, single-effect, hot-water absorption machine, installed at UTS. These models are further used in a simulation tool for energy optimisation of this absorption machine. The thesis encompasses components of testing, modelling and energy optimisation of small capacity absorption machines. The first task is obtaining highly reliable data from our installation. This part involves several steps: test planning, data modelling, uncertainty estimation and analysis of results. [Saket Sinha]

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Refrences :

[1] Cosenza, F., Vliet, G.C., "Absorption in Falling Water/LiBr Films on Horizontal Tubes", ASHRAE Transaction, paper No. 3379 (RP-405), Part2, pp.693-701,1989.[2] Jani, S., Saidi, M.H., Mozaffari, A.A. and Heydari, A., "Modeling Heat and Mass Transfer in Falling Film Absorption Generators", Scientia Iranica, Vol. 11, pp. 81-91, 2004.[3] Parken, W.H. , Fletcher, L.S., Sernas, V., Han, J.C., "Heat Transfer Through Falling Film Evaporation and Boiling on Horizontal Tubes". Transaction of the ASME, Vol. 112, pp. 744-750, 1990.[4] Bird, R.B., Stewart, W.E. and Lightfoot, E.N., "Transport Phenomena". University of Wisconsin, John Wiley & Sons, Inc. New York, Chap. 2, pp. 34-71, 1960.

Velocity distributions in (r,θ) directions are evaluated by solving simultaneous simplified Navier-Stokes equations (NSE) and continuity equation (CE) in polar coordinate. The analysis is based on steady state laminar flow of thin falling liquid film on a horizontal circular tube, for cases in which traction on the film surface is considered negligible. It is a common geometry for part of engineering problems such as evaporator, condenser, absorber, generator of absorption chillers and other similar units in mechanical and chemical engineering. Knowledge of the velocity profiles is usually needed for: 1- solving governing energy and species equations 2- estimating the average and film surface velocity, and 3- evaluating film thickness distribution and its gradient. Two models of velocity distributions are considered, namely actual model and simplified model. Models are compared not only with each other but also with semi actual model in (x,y) coordinate given in the literatures. The average and film surface velocity profiles and film thickness distribution for these models have been shown in various conditions. The results clearly show that the larger flow rates and / or smaller tube diameter increases the calculation error.

دانلودThree model choices of actual parallel cycle of direct fired double effect "LiBr-H2O" absorption chillers(DEAC) are simulated. Our aim is to estimate the influence of different variables on the cycleperformance with the final goal of optimum cycle components. The simulation algorithm of the cycle andits components are presented. These three choices are compared according to their cycle "LiBr-H2O" (PT-X) equilibrium chart, considering fabricating efforts, operating costs and maintenance. The selectedoptimum cycle with the optimum input and output data is investigated. The output data for three choicesare shown and compared at similar design conditions.

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