Affiliation:
1. Technische Universität Berlin, Marchstraße 18, D-10587 Berlin, Germany
2. Dipartimento di Ingegneria Industriale, Università degli Studi di Bergamo, Viale Marconi, 24044 Dalmine (BG), Italy
Abstract
The efficient operation of a solar cooling system strongly depends on the chiller behavior under part load conditions, since driving energy and cooling load are never constant. For this reason, the performance of a single stage, hot water driven 30 kW H2O/LiBr-absorption chiller employed in a solar cooling system with a field of 350 m2 evacuated tube collector has been analyzed under part load conditions with both simulations and experiments. A simulation model has been developed for the whole absorption chiller (Type Yazaki WFC-10), where all internal mass and energy balances are solved. The connection to the external heat reservoirs of hot, chilled, and cooling water is done by lumped and distributed UA values for the main heat exchangers. In addition to an analytical evaporator model—which is described in detail—experimental correlations for UA values have been used for the condenser, generator, and solution heat exchanger. For the absorber, a basic model based on the Nusselt theory has been employed. The evaporator model was developed, taking into account the distribution of refrigerant on the tube bundle, as well as the change in operation from a partially dry to an overflowing evaporator. A linear model is derived to calculate the wetted area. The influence of these effects on cooling capacity and coefficient of performance (COP) is calculated for three different combinations of hot and cooling water temperature. The comparison to experimental data shows a good agreement in the various operational modes of the evaporator. The model is able to predict the transition from partially dry to an overflowing evaporator quite well. The present deviations in the domain with high refrigerant overflow can be attributed to the simple absorber model and the linear wetted area model. Nevertheless, the results of this investigation can be used to improve control strategies for new and existing solar cooling systems.
Subject
Energy Engineering and Power Technology,Renewable Energy, Sustainability and the Environment
Reference14 articles.
1. Analysis of the Part Load Behaviour of Sorption Chillers With Thermally Driven Solution Pumps;Albers
2. Investigation Into the Influence of the Cooling Water Temperature on the Operating Conditions of Thermosyphon Generators;Albers
3. Kruse, C. -D.
, 1999, “Berichtsteil II: Simulation und experimentelle Identifikation des Betriebsverhaltens von kleinen heißwasserbetriebenen Absorptionskältemaschinen,” TU Dresden, Institut für Energietechnik und Fernwärme-Forschungsinstitut, Hannover eV, Koordinierter Schlussbericht AiF Fördernummer 11259 B.
4. ‘The Intertube Falling Film: Part 1—Flow Characteristics, Mode Transitions and Hysteresis;Hu;ASME J. Heat Transfer
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献