Thermodynamic Investigation and Optimization of a Residential Absorption Air conditioner functioning, using variance method
Nabil Ben Hafsia, Bechir Chaouachi
: nabilbenhafsia@yahoo.fr
Ecole nationale d’ingénieurs de Gabès
Mots clés : absorption air conditioner, variance study, simulation, optimization analysis, severe working condition
Résumé :
The identification of a thermodynamic system and the optimization of its functioning in steady regime require the determination of various quantities described by a number of intensive and extensive parameters. These necessary parameters are called variance of the system.
This paper will talk about the identification of some criteria participating in the improvement of the coefficient of performance "COP" of an air conditioner with a cooling capacity of around 17.5 kW. This chiller operates on a single effect absorption cycle and uses natural gas as fuel. This paper has two main parts:
• In the first part, we define first the variance and its calculation principle for an open thermodynamic physical system, as well as for a cyclic thermal machine and then we conduct a study of a single-effect absorption chiller variance using three absorbent-refrigerant mixtures, which are: water-ammonia (-), - couples and -- saline solution which is a mixture feebly studied as absorption cycle fluid. The object is to determine the independent operating variables of the system.
• In the second part, a numerical simulation is conducted to identify firstly the impact of the couple choice on the air conditioner COP and determine then the optimal mixture for the system functioning. Secondly an optimization investigation is carried out to determine the system optimal functioning. The optimization study consists to maximize the absorption system COP when the variation of COP with generator temperature is considered. The value of this temperature corresponding to the maximum COP is called optimal generator temperature. The influence of system design parameters and operating conditions on this optimal generator temperature can be investigated through a parametric analysis. An appropriate examination is accomplished to determine the optimal system functioning for severe climatic condition encountered in hot countries. This critical condition will subsequently serve, in perspective, as the basis for the design of the absorption chiller generator whose burner works with natural gas.
Work In Progress