Session: 08-03-01: 4E Analysis and Optimization of Thermodynamic Systems

Paper Number: 69900

Start Time: Wednesday, 05:30 PM

69900 - A Study on the Performance of Solar Driven Absorption Chiller in Terms of Coefficient Of Performance and Exergy Efficiency 

Conventional technology cooling systems consume electrical energy in order to power their mechanical compressor. When this electrical energy comes from the power grid the utilization of traditional vapor compression systems is accompanied by the following disadvantages:

 

Increase of carbon dioxide (CO2) emissions due to the fact that the largest percentage of electrical energy is produced by burning fossil fuels (Fig.1). Carbon dioxide emissions accentuate the greenhouse effect and by extension global warming.

Contribute to the depletion of fossil fuels. Estimates about the depletion of fossil fuels indicate 107 years for coal, 37 years for gas and only 35 years for oil.

Their extensive and simultaneous use during summer months causes serious problems to the power plants and electrical network, increasing the danger of power outages and black outs.

Their operational cost is relatively high.

 

Apart from the above-mentioned disadvantages for which the consumption of grid supplied electrical energy is responsible, there are more disadvantages concerning the refrigerants. Specifically, commonly used refrigerants such as ChloroFluoroCarbons (CFCs) and HydroChloroFluoroCarbons (HCFCs) contribute to the depletion of ozone layer.

 

Thermally driven chillers also known as sorption heat pumps have drawn considerable attention in recent years. They can be divided into two main categories: absorption (liquid-vapor) and adsorption (solid-vapor) systems. Even though sorption cycles have relatively lower coefficient of performance compared to conventional refrigeration cycles, however they prevail in terms of heat source, electric consumption for moving parts, mechanical wear etc. In order to enhance their environmentally friendly operation, sorption chillers can be driven by solar power.

In this study a solar driven absorption chiller which utilizes evacuated tubes collectors and intermediate heat exchanger is simulated. The model’s governing equations derived from the energy balance on each component of the system are solved numerically. The COP, the solar COP, the overall exergy efficiency, the required collectors’ surface and the collectors and tank normalized cost are calculated for various heat source temperatures. Moreover, all calculations are repeated for various values of heat exchanger effectiveness in order to determine the maxima and minima of the system’s operation. It is proved that the maxima are reached at lower inlet temperatures for higher values of the intermediate heat exchanger

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Presenting Author: M. T. Nitsas National Technical University of Athens

Authors:

M. T. Nitsas National Technical University of Athens
I. P. Koronaki National Technical University of Athens